MEMCAL
John Marshall Williamson
Memorial
QUAIN'S
ELEMENTS OF ANATOMY
EDITED BY
WILLIAM SHARPEY, M.D., F.R.S.
PROFESSOR OF ANATOMY AND PHYSIOLOGY IN UNIVERSITY COLLEGE, LONDON
ALLEN THOMSON, M.D., F.R.S.
PROFESSOR OF ANATOMY IN THE UNIVERSITY OF GLASGOW
JOHN CLELAND, M.D.
PROFESSOR OF ANATOMY IN QUEEN'S COLLEGE, OALWAY
IN TWO VOLUMES
ILLUSTRATED BY UPWARDS OF 800 ENGRAVINGS ON WOOD.
VOL. I.
LONDON
JAMES WALTON
BOOKSELLER AND PUBLISHER TO UNIVERSITY COLLEGE
137, GOWER STREET.
1867.
LONDON !
BRADBUHY, EVANS^ AND CO., PUINTERS, WHITEFRIAR8.
186?
ADVERTISEMENT.
THE successive Editions of Dr. Jones Quain's "Elements of
Anatomy " were, up to the fourth inclusive, published under the
superintendence of the Author. The duty of editing the fifth
edition was undertaken by Mr. Richard Quain, then Professor of
Anatomy in University College, and Dr. Sharpey ; the several
parts being apportioned between them, as follows, viz. : The
General Anatomy to Dr. Sharpey, with the Descriptive Anatomy
of the Brain, the Heart, and of the Organs of Respiration, Voice,
Digestion, Urine, and Generation ; and to Mr. Quain the remaining
portion of the Descriptive Anatomy, comprehending the Bones,
Muscles, Articulations, Fasciae, Vessels, Nerves, and the Organs of
the Senses, together with the Surgical Anatomy of the different
regions. On that occasion extensive changes were made through-
out the work, and a great part was entirely re-written.
The increasing claims of professional duty having prevented
Mr. Quain from continuing his services in preparing the Sixth
Edition, his place was taken by Mr. Ellis, his successor in the
Chair of Anatomy at University College, who was accordingly
associated with Dr. Sharpey, and edited that portion of the work
which had previously fallen to the share of his predecessor.
In the present edition the General Anatomy, entirely re-written
by Dr. Sharpey for the fifth edition, has been again revised by him,
and has undergone extensive changes, adapting it to the present
state of the science. The whole of the Descriptive Anatomy has
been edited by Dr. Thomson and Dr. Cleland. .The text of this
part has been thoroughly revised, and in great measure recast by
Dr. Cleland, with the assistance and supervision of Dr. Thomson.
New figures have in most cases been substituted for those of
former editions, drawn on a larger scale, or deemed otherwise more
vi ADVERTISEMENT.
illustrative of the objects, and many additional figures have been
introduced. The duty of selecting these figures and superintending
their execution has been performed by Dr. Thomson. All those of
the bones, and most of those of the joints have been drawn from
the natural objects. Many of the figures of the muscles were also
drawn from nature, and most of the others, though founded
on approved published prints, have been modified and finished
from actual dissections. When figures are not original, the sources
whence they have been taken are faithfully indicated. Of those
borrowed from the works of Kb'lliker, Sappey, and Frey, a certain
number are impressions from electro-type copies, obtained through
the courtesy of the authors and publishers of these works. The
new cuts have been executed chiefly by Messrs. Robert Tennant
and Stephen Miller, of Glasgow ; the former as draughtsman, the
latter as engraver. Several of those new to the General Anatomy
are by Mr. W. H. Wesley, of London.
The Section on Surgical Anatomy has been reprinted as ori-
ginally written by Professor R Quain, with only a few verbal
alterations.
Instead of the paragraphs headed " dissection," distributed
through the work in former editions, it has been thought preferable
to supply a systematic but concise set of directions for dissection
at the end of the book. Whilst it is hoped that this chapter will
add to the utility of the work, it is by no means intended that
it should supersede the use of special Manuals of Practical
Anatomy.
CONTENTS OF THE FIEST VOLUME.
ELEMENTS OF ANATOMY.
INTRODUCTION
PAGE
i
GENERAL ANATOMY.
PAGE
GENERAL CONSIDERATIONS ON THE
TEXTURES iii
Physical Properties . . . iv
Chemical Composition . . v
Vital Properties . . . . vii
DEVELOPMENT OF THE TEXTURES ix
Structure of Cells . . . xiii
. Production of Cells . . . xv
Motion of the Protoplasm in
Cells xix
Relation of Cells to the formation
of textures . . . . xxi
Intercellular substance . . xxiii
NUTRITION and Regeneration of
the Textures .... xxiv
THE BLOOD xxvii
Physical and Organic Constitu-
tion ...... xxvii
Chemical Composition . . xxxiii
Red Corpuscles . . . xxxiii
Liquor Sanguinis . . xxxvii
Origin of Fibrin . . xxxviii
Serum .... xxxix
Mean Composition of the Blood xli
Different kinds of Blood
Coagulation of the Blood
THE LYMPH AND CHYLE
&Jf .'..
Formation of the Corpuscles of th
Lymph and Chyle
Formation of the Blood- Cor
puscles ....
EPIDERMIC, EPITHELIAL, OR CUTI
CULAR TISSUE .
General nature .
Scaly Epithelium .
Columnar Epithelium
Spheroidal Epithelium
Ciliated Epithelium .
Motion of Cilia .
PIGMENT
ADIPOSE TISSUE
xlii
xliv
xlvii
xlviii
xlviii
1
1
Hi
Iii
liii
Ivi
Iviii
Iviii
Ixi
Ixiii
Ixv
CONNECTIVE TISSUE . . . Ixix
Areolar Tissue . . . . Ixix
Fibrous Tissue .... Ixxir
Yellow or Elastic Tissue . . Ixxvi
Special Varieties of Connective
Tissue .... Ixxviii
CARTILAGE Ixxx
Hyaline Cartilage . . . Ixxxi
Elastic or Yellow Cartilage . Ixxxv
Fibro- Cartilage . . . Ixxxvi
BONE OR OSSEOUS TISSUE . Ixxxvii
External Configuration . Ixxxvii
Physical Properties . . Ixxxviii
Chemical Composition . Ixxxix
Structure . . . . . xc
Periosteum . . . . c
Marrow ..... c
Blood-vessels, &c. ci
Formation and growth of Bone . cii
Ossification in Membrane . . ciii
Ossification in Cartilage . cvi
MUSCULAR TISSUE .... cxv
General Structure of Voluntary
Muscles .... cxv
Structure of the Fibres . . cxviii
Connection with Tendons . . cxxi
Blood-vessels and Lymphatics . cxxiii
Nerves ..... cxxiv
Involuntary Muscles . . . cxxiv
Development of Muscle . . cxxvi
Growth of Muscles . . cxxvii
Chemical Composition of Muscle cxxviii
Physical and Vital Properties of
Muscle .... cxxix
NERVOUS SYSTEM . . . . cxxxi
Chemical Composition . cxxxiii
Structural Elements . . cxxxiv
Ganglia cxli
Cerebro-Spinal Nerves . . . cxliv
The Sympathetic or Ganglionic
Nerve ..... clviii
Vital Properties of the Nervous
System ..... clxii
Development of Nerves . . clxiii
CONTENTS.
PAGE
BLOOD-VESSELS . ... clxv
Arteries ..... clxvii
Veins ...... clxxii
Capillary Vessels , . . . clxxv
Development of Blood- Vessels . clxxx
ABSORBENT OR LYMPHATIC SYS-
TEM clxxxii
Distribution and Origin . clxxxii
Structure .... clxxxiv
Absorbent Glands . . . clxxxvi
SEROUS MEMBRANES . . . cxci
SYNOVIAL MEMBRANES . . . cxciii
Mucous MEMBRANES . . . cxcv
Structure .... cxcvii
PAGE
Glands of Mucous Membrane . cc
Nerves ..... cci
Secretion cci
SKIN ...... cci
The Epidermis or Cuticle . . cci
The True Skin, its Structure . cciii
Papillae .... cciv
Blood- vessels and Lymphatics ccv
Nerves ..... ccvi
Nails ..... ccvi
Hairs ..... ccviii
Glands of the Skin . . ccxv
SECRETING GLANDS . . . ccxviii
DUCTLESS OR VASCULAR GLANDS ccxxvi
SPECIAL ANATOMY.
DIVISION L SYSTEMATIC OR DESCRIPTIVE ANATOMY.
PAGE
SECTION I. OSTEOLOGY . 2
The Skeleton ... 2
I. THE VERTEBRAL COLUMN . 3
Moveable Vertebrae . . 4
General Characters . . 4
Characters Peculiar to
Groups of Vertebrae . 5
Dorsal Vertebrae . . 5
Lumbar Vertebrae . . 6
Cervical Vertebrae . . 7
The First and Second Cer-
vical Vertebrae . . 8
Fixed or United Vertebrae . 10
Sacrum 10
Coccyx . . . . 12
The Vertebral Column as a
whole .... 13
Development of the Ver-
tebrae .... 15
Periods of Ossification . . 20
Theoretical Comparison of
the Vertebrae . . . 21
II. THE THORAX ... 23
The Sternum or Breast-
Bone . . . . 23
The Eibs .... 24
The Thorax as a whole . . 27
Development of the Ribs and
Sternum . . .27
Periods of Ossification of the
Ribs and Sternum . . 29
III. THE BONES OF THE SKULL 29
Occipital Bone ... 29
Frontal Bone . . . 33
Temporal Bone . . '35
Sphenoid Bone . . . 38
Ethmoid Bone ... 42
Superior Maxillary Bone . 44
Palate Bone ... 46
Vomer . . . . . 48
PAGE
Malar Bone ... 49
Nasal Bone . . 49
Lachrymal Bone . . 50
Inferior Tnrbinated Bone . 50
Inferior Maxillary Bone . . 51
Hyoid Bone . . 52
THE SKULL AS A WHOLE . . 53
The Sutures ... 53
General Conformation of the
Skull . . . . 55
Exterior. ... 55
Interior . . . . 60
Development of the Skull . 64
Periods of Ossification of the
Bones of the Skull . 70
The Vertebral Theory of the
Skull .... 71
The Various Forms of the
Skull . . . . 72
IV. BONES OF THE UPPER LIMB 74
Scapula .... 74
Clavicle. . . . . 77
Humerus . . . .78
Radius 80
Ulna 81
Carpus . . . . . 83
Scaphoid Bone . . 84
Semilunar Bone . . . 84
Cuneiform Bone . . 84
Pisiform Bone . . . 85
Trapezium ... 85
Trapezoid Bone . . . 85
Os Magnum ... 85
Unciform Bone . . . 86
Metacarpus ... 86
Digital Phalanges . . . 87
Development of the Upper
Limb .... 88
Periods of Ossification of the
Bones of the Upper Limb 90
CONTENTS.
PAGE
V. THE PELVIS AND LOWER LIMB 93
Innominate Bone . 93
The Pelvis .... 97
Femur 100
Patella . . . .103
Tibia 103
Fibula . . . .105
Tarsus 106
Calcaneum, . . .107
Astragalus . . . . 107
Cuboid Bone . . .108
Scaphoid Bone . . . 108
Cuneiform Bones . .109
Metatarsus . . . . 109
Digital Phalanges . .no
The Bones of the Foot as a
whole . . . .no
Development of the Lower
Limb . . . . 1 10
Periods of Ossification of the
Bones of the Lower Limb 112
Comparison of the Upper
with the Lower Limb . 115
Relation of the Limbs to the
Segments of the Trunk 117
The Skeleton adapted to the
Erect Posture . .117
SECTION II. ARTHROLOGY 118
Modes of Articulation . nS
Motions of the Bones in the
joints . . . . 120
ARTICULATIONS OF THE TRUNK
AND HEAD . . .121
Articulations of the Verte-
bral Column . . . 121
Articulations of the Atlas,
Axis, and Occipital Bone 125
Articulations of the Ribs . 128
Temporo-Maxillary Articu-
lation . . . . 132
ARTICULATIONS OF THE UPPER
LIMB . . . .134
The Scapulo-Clavicular Arch 134
The Shoulder-Joint . . 136
Articulations of the Fore-
arm and Elbow . .138
The Wrist-Joint and Articu-
lation of the Hand . 142
Connection of the Metacarpal
Bones with the Carpus,
and with each other . 144
Articulations of the Metacar-
pal Bones with the Pha-
langes, and of the Pha-
langes with each other. 145
ARTICULATIONS OFTHE PELVIS 147
A UT ICULATIONS OF THE LOWKB.
LIMB . . . . 151
The Hip- Joint . . -151
The Knee- Joint . . . 153
Articulations of the Leg and
Ankle. . . .158
Articulations of the Foot . 160
VOL. I.
PAGE
I SECTION III. MYOLOGY . 167
MUSCLES OF THE HEAD AND
NECK . . . . 169
Superficial Muscles . . 169
Epicranial Muscles . . 169
Muscles of the Eyelids . 171
Muscles of the Nose . 173
Muscles of the Lips and
Mouth . . -175
Muscles of the Orbit . . 1 79
Action of . . 179, 501*
Muscles of the Jaw . . 181
Submaxillary Muscles . . 183
A. Muscles connecting
the Hyoid Bone with
the Skull . . .183
B. Muscles of the Tongue 185
Muscles of the Pharynx and
Soft Palate . . . 187
Muscles depressingthe Hyoid
Bone . . . .191
Flexor Muscles of the Neck 193
Fascias of the Head and Neck 196
MUSCLES OF THE UPPER LIMB 198
Muscles attach ing the Upper
Limb to the Trunk pos-
teriorly . . . 200
Muscles attaching the Upper
Limb to the Trunk an-
teriorly . ... 203
Muscles of the Shoulder . 208
Muscles of the Arm. . . 212
Muscles of the Fore- Ami . 215
a, Anterior and Inner
Regions (Flexors and
Pronators) . . .215
b, Posterior and Outer
Regions (Extensors and
Supinators) . . . 220
Muscles of the Hand . . 225
Muscles of the Thumb . 225
Muscles of the Little Finger 227
Action of the Muscles of the
Fore-Arm and Hand . 228
Fascite of the Upper Limb . 229
MUSCLES OF THE TRUNK . 232
Dorsal Muscles of the Trunk
(Muscles of the Back) . 232
Dorsal and Lumbar Fasciae 240
Muscles of the Thorax . . 240
Diaphragm . . . 243
Movements of Respiration . 246
MUSCLES OF THE ABDOMEN . 248
Fasciae of the Abdomen . 257
Fasciae of the Perinreum . 259
Fascise of the Pelvis . . 260
Muscles of the Perinseum . 261
A. In the Male . .261
B. In the Female . . 265
MUSCLES OF THE LOWER LIMB 266
Muscles of the Hip and Thigh 266
Gluteal Region . . 266
Posterior Femoral Region
(Hamstring Muscles) . 270
b*
CONTENTS.
PAGE
Iliac Region . . . 271
Anterior Femoral Region 273
Internal Femoral Region
(Adductor Muscles) . 276
Action of the Muscles of the
Hip and Thigh . .279
Muscles of the Leg and Foot 279
Anterior Region of the Leg 279
External Region . . 282
Posterior Region . . 282
Short Plantar Muscles . 289
Muscles of the Great Toe 289
Muscles of the Little Toe 290
Action of the Muscles of the
Leg and Foot . .291
Fasciae of the Lower Limb . 292
SECTION IV. ANGEIOLOGY . 297
THE HEART .... 297
Relation to Surrounding Parts 297
The Mediastinum . . . 297
Pericardium . . . 300
External Form of the Heart 302
Interior of the Heart . . 304
General Description . . 304
Special Description . 308
Position of the Parts of the
Heart with Relation to
the Wall of the Thorax 313
.Fibrous and Muscular Struc-
ture of the Heart . . 316
Vessels and Nerves . .321
Weight and Dimensions . 321
Development of the Heart
and Great Blood-Vessels 323
Peculiarities of the Foetal
Heart and Great Vessels.
Foetal Circulation . 327
PULMONAKY VESSELS . . 33!
Pulmonary Artery and Veins 33 1
SYSTEMIC VESSELS . . 332
ARTERIES 332
AORTA 332
Arch of the Aorta . . . 332
Peculiarities of the Arch of
the Aorta . . .336
BRANCHES or THE ARCH OF
THE AORTA . --338
Coronary Arteries . . 338
Innominate Artery . . 340
Common Carotid Arteries . 341
External Carotid Artery . 345
Branches of the External
Carotid Arteiy . . 346
Superior Thyroid Artery . 346
Lingual Artery . . . 348
Facial Artery . . . 349
Occipital Artery . . . 35 1
Posterior Auricular Artery 353
Temporal Artery . '353
Internal Maxillary Artery 354
Ascending Pharyugeal Ar-
tery . . . .357
Internal Carotid Artery . . 359
PAGE
Branches of the Internal Ca-
rotid Artery . . . 360
Ophthalmic Artery. . 360
Anterior and Middle Cere-
bral Arteries . . 363
Circle of Willis . . . 363
Subclavian Arteries . . 364
Branches . . . . 367
Vertebral Artery . . 367
Thyroid Axis . . . 371
Inferior Thyroid . . 371
Suprascapular . . . 371
Transverse Cervical . 373
Internal Mammary A rtery 374
Superior Intercostal and
Deep Cervical Arteries 376
Axillary Artery . . -377
Branches . . . . 377
External Thoracic Branches 379
Subscapular Artery. . 379
Circumflex Arteries . . 380
Brachial Artery . . .381
Branches . . . . 383
Ulnar Artery . . . 388
Branches . ... 389
Recurrent Branches . 389
Interosseous Artery . . 390
Muscular Branches . . 391
Carpal Branches , . 391
Superficial Palmar Arch . 393
Radial Artery . . . 394
Branches . . . 397
Deep Palmar Arch . . 400
Various Conditions of the
Arteries of the Hand . 400
THORACIC AORTA . . . 401
Branches .... 402
Bronchial Arteries . . 402
(Esophageal Arteries . 402
Intercostal Arteries . . 402
ABDOMINAL AORTA . . 404
A. Visceral Branches . . 406
Cceliac Artery or Axis . 406
Coronary Artery of the
Stomach . . . 407
Hepatic Arteiy . . . 408
Splenic Artery . . 408
Superior Mesenteric Artery 410
Branches . . . 410
Inferior Mesenteric Artery 412
Branches . . .412
Anastomoses on the Intes-
tinal Tube . . . 412
Capsular or Suprarenal Ar-
teries . . . .413
R enal or Emulgent Arteri es 414
Peculiarities . -414
Spermatic and Ovarian Ar-
teries . . . . 414
B. Parietal Branches of the
Abdominal Aorta . 416
Inferior Phrenic Arteries 416
Branches . . .416
Lumbar Arteries . . 417
CONTEXTS.
PAGE
Branches . . . 417
Minute Anastomoses of the
Visceral and Parietal
Branches of the Abdo-
minal Aorta . . 417
Middle Sacral Artery . 418
Common Iliac Arteries . 418
Internal Iliac Artery . . 420
Hypogastric Artery . 420
Branches of the Internal
Iliac Artery . . . 421
Vesical Arteries . .421
Uterine and Vaginal Arte-
ries . . . 422
Obturator Artery . . 423
Branches . . . 424
Pudic Artery . . . 425
Branches . . . 426
Sciatic Artery . . 429
Gluteal Artery . . . 429
Ilio- Lumbar Artery . 429
Lateral Sacral Arteries . 430
External Iliac Artery . . 431
Epigastric Artery . .432
Circumflex Iliac Artery . 433
Femoi'al Artery . . . 434
Superficial Inguinal
Branches . . . 437
Deep Femoral Artery . 437
Muscular Branches . . 439
Anastomotic Artery . 440
Popliteal Artery . . . 441
Branches . . . 442
Posterior Tibial Artery . 441
Small Branches . . . /]/]/[
Peroneal Artery . . /\<\/\
Plantar Arteries . . . 446
Branches . . . 447
Anterior Tibial Artery . . 448
Branches . . . 449
Dorsal Artery of the Foot . 450
VEINS 452
UPPER VENA CAVA . . 453
Innominate or Braehio-
Cephalic Veins . . 453
Lateral Tributaries . 453
Veins of the Face, Neck
and Head . -455
Facial Vein . . . 455
Temporal Vein . -457
Internal Maxillary Vein 457
Facial Communicating
Vein . . -457
PAGE
External Jugular Vein 459
Internal Jugular Vein . 459
Venous Circulation within
the Cranium . . 460
Cerebral Veins . . 460
Cranial Sinuses . .461
Ophthalmic Vein . . 464
Veins of the Diploe . 465
Superficial Veins of the
Upper Limb . . 466
Deep Veins of the Upper
Limb . . . 467
Axillary Vein . . . 468
Subclavian Vein . . 469
Azygos Veins . . . 469
Veins of the Spine . . 471
LOWER VENA CAVA . . 473
Veins of the Lower Limb and
Pelvis . . . . 475
Superficial Veins of the
Lower Limb . -475
Deep Veins of the Lower
Limb . . . . 476
Femoral Vein . . . 476
External Iliac Vein . . 477
Internal Iliac Vein . . 477
Common Iliac Vein . . 479
PORTAL SYSTEM OF VEINS . 479
Portal Vein or Vena Portse . 4/9
Coronary Vein of Stomach 480
Splenic Vein . . . 480
Mesenteric Veins . .481
VEINS OF THE HEART . . 482
Development of the Great
Veins .... 483
ABSORBENTS . . . . 486
Thoracic Duct . . .487
Eight Lymphatic Duct . . 488
Lymphatics of the Lower
Limb, and Surface of the
Lower Half of the Trunk 488
Absorbents of the Abdomen
and Pelvis . . . 490
Lymphatics of the Thorax . 495
Lymphatics of the Upper
Limb, and of the Breast
and Back . . . 497
Lymphatics of the Head and
Neck .... 499
NOTE. On Action of Muscles of
the Eye . . .501*
ELEMENTS OF ANATOMY,
INTRODUCTION.
Division of natural Bodies.- The material objects which exist in nature
belong to two great divisions ; those which are living or which have lived,
and those which neither are nor have ever been endowed with life. The
first division comprehends animals and plants, the other mineral sub-
stances.
In a living animal or plant, changes take place, and processes are carried
on, which are necessary for the maintenance of its living state, or for the
fulfilment of the ends of its being ; these are termed its functions, and
certain of these functions, being common to all living beings, serve among
other characters to distinguish them from inert or mineral substances.
Such are the function of nutrition, by which living beings take extraneous
matter into their bodies, and convert it into their own substance, and the
function of generation or reproduction, by which they give rise to new
individuals of the same kind, and thus provide for the continuance of their
species after their own limited existence shall have ceased.
But, in order that such processes may be carried on, the body of a living
being is constructed with a view to their accomplishment, and its several
parts are adapted to the performance of determinate oftices. Such a consti-
tution of body is termed organisation, and those natural objects which possess
it are named organised bodies. Animals and plants, being so constituted,
are organised bodies, while minerals, not possessing such a structure, are
inorganic.
Object of Anatomy. The object of anatomy, in its most extended sense,
is to ascertain and make known the structure of organised bodies. But the
science is divided according to its subjects ; the investigation of the
structure of plants forms a distinct study under the name of Vegetable
Anatomy, and the anatomy of the lower animals is distinguished from that
of man or human anatomy under the name of Comparative Anatomy.
Organs and Textures. On examining the structure of an organised body,
we find that it is made up of members or organs, through means of which
its functions are executed, such as the root, stem, and leaves of a plant,
and the heart, brain, stomach, and limbs of an animal ; and further, that
these organs are themselves made up of certain constituent materials named
tissues or textures, as the cellular, woody, and vascular tissues of the
vegetable, or the osseous, muscular, connective, vascular, and various
others, which form the animal organs.
ii INTRODUCTION.
Most of the textures occur in more than one organ, and some of them
indeed, as the connective and vascular, in nearly all, so that a multitude of
organs, and these greatly diversified, are constructed out of a small number
of constituent tissues, just as many different words are formed by the
varied combinations of a few letters ; and parts of the body, differing
widely in form, construction, and uses, may agree in the nature of their
component materials. Again, as the same texture possesses the same
essential characters in whatever organ or region it is found, it is obvious
that the structure and properties of each tissue may be made the subject
of investigation apart from the organs into whose formation it enters.
General and Descriptive Anatomy. These considerations naturally point
out to the Anatomist a twofold line of study, and have led to the subdivi-
sion of Anatomy into two branches, the one of which treats of the nature
and general properties of the component textures of the body : the other
treats of its several organs, members, and regions, describing the outward
form and internal structure of the parts, their relative situation and mutual
connection, and the successive conditions which they present in the pro-
gress of their formation or development. The former is usually named
" General" Anatomy, or "Histology;"* the latter "Descriptive"
Anatomy.
* From Iffrbs, a web.
GENEKAL ANATOMY.
GENERAL CONSIDERATIONS ON THE TEXTURES.
Enumeration of the Textures. The human body consists of solids and
fluids. Only the solid parts can be reckoned as textures, properly so
called ; still, as some of the fluids, viz. the blood, chyle, and lymph,
contain in suspension solid organised corpuscles of determinate form and
organic properties, and are not mere products or secretions of a particular
organ, or confined to a particular part, the corpuscles of these fluids,
though not coherent textures, are to be looked upon as organised consti-
tuents of the body, and as such may not improperly be considered along
with the solid tissues. In conformity with this view the textures and
other organised constituents of the frame may be enumerated as fol-
lows :
The blood, chyle, and lymph.
Epidermic tissue, including epithelium, cuticle, nails, and hairs.
Pigment.
Adipose tissue.
Connective tissue, viz.
Areolar tissue.
Fibrous tissue.
Elastic tissue.
Cartilage and its varieties.
Bone or osseous tissue.
Muscle.
Nerve.
Blood-vessels.
Absorbent vessels and glands.
Serous and synovial membranes.
Mucous membrane.
Skin.
Secreting glands.
Vascular or ductless glands.
Organic Systems. Every texture taken as a whole was viewed by Bichat
as constituting a peculiar system, presenting throughout its whole extent
in the body characters either the same, or modified only so far as its local
connections and uses render necessary ; he accordingly used the term
iv GENERAL CONSIDERATIONS OX THE TEXTURES.
" organic systems" to designate the textures taken in this point of view,
and the term has been very generally employed by succeeding writers.
Of the tissues or organic systems enumerated, some are found iii nearly
every organ ; such is the case with the connective tissue, which serves as
a binding material to hold together the other tissues which go to form an
organ ; the vessels, which convey fluids for the nutrition of the other
textures, and the nerves, which establish a mutual dependence among
different organs, imparting to them sensibility, and governing their move-
ments. These were named by Bichat the "general systems." Others
again, as the cartilaginous and osseous, being confined to a limited num-
ber or to a particular class of organs, he named "particular systems."
Lastly, there are some tissues of such limited occurrence that it has
appeared more convenient to leave them out of the general enumeration
altogether, and to defer the consideration of them until the particular
organs in which they are found come to be treated of. Accordingly, the
tissues peculiar to the crystalline lens, the teeth, and some other parts,
though equally independent textures with those above enumerated, are for
the reason assigned not to be described in this part of the work.
Structural Elements. It is further to be observed, that the tissues above
enumerated are by no means to be regarded as simple structural elements ;
on the contrary, many of them are complex in constitution, being made up
of several more simple tissues. The blood-vessels, for instance, are com-
posed of several coats of different structure, and some of these coats
consist of more than one tissue. They are properly rather organs than
textures, although they are here included with the latter in order that
their general structure and properties may be considered apart from their
local distribution ; but indeed it may be remarked, that the distinction
between textures and organs has not in general been strictly attended to
by anatomists. The same remark applies to mucous membrane and the
tissue of the glands, which structures, as commonly understood, are highly
complex. Were we to separate every tissue into the simplest parts which
possessed assignable form, we should resolve the whole into a very few
constructive elements; and, having regard to form merely, and not to
difference of chemical constitution, we might reduce these elements to the
following, viz. 1. simple fibre; 2. homogeneous membrane, either spread
out or forming the walls of tubes or cells ; and 3. globules or granules,
varying in diameter from the T T<roZ)* n to the ^ ~^th of an inch. These,
with a quantity of amorphous matter, homogeneous or molecular, might be
said, by their varied combinations, to make up the different kinds of
structure which we recognise in the tissues ; and if we take into account
that the chemical nature of these formative elements and of the amorphous
matter may vary, it will be readily conceived that extremely diversified
combinations may be produced.
PHYSICAL PROPERTIES.
The animal tissues like other forms of matter are endowed with various
physical properties, such as consistency, density, colour, and the like. Of
these the most interesting to the Physiologist is the property of imbibing
fluids, and of permitting fluids to pass through their substance, which
is essentially connected with some of the most important phenomena that
CHEMICAL COMPOSITION OF THE TEXTURES. v
occur in the living body, and seems indeed to be indispensable for the main-
tenance and manifestation of life.
All the soft tissues contain water, some of them more than four-fifths of their
weight ; this they lose by drying, and with it their softness and flexibility, and so
shrink up into smaller bulk and become hard, brittle, and transparent ; but when the
dried tissue is placed in contact with water, it greedily imbibes the fluid again, and
recovers its former size, weight, and mechanical properties. The imbibed water is no
doubt partly contained mechanically in the interstices of the tissue, and retained
there by capillary attraction, like water in moist sandstone or other inorganic porous
substances ; but the essential part of the process of imbibition by an animal tissue is
not to be ascribed to mere porosity, for the fluid is not merely lodged between the
fibres or laminae, or in the cavities of the texture; a part, probably the chief part, is
incorporated with the matter which forms the tissue, and is in a state of union with
it, more intimate than could well be ascribed to the mere inclusion of a fluid in the
pores of another substance. Be this as it may, it is clear that the tissues, even in
their inmost substance, are permeable to fluids, and this property is indeed necessary,
not only to maintain their due softness, pliancy, elasticity, and other mechanical
qualities, but also to allow matters to be conveyed into and out of their substance in
the process of nutrition.
CHEMICAL COMPOSITION.
Ultimate Constituents. The human body is capable of being resolved by
ultimate analysis into chemical elements, or simple constituents, not differ-
ing in nature from those which compose mineral substances. Of the
chemical elements known to exist in nature, the following have been
discovered in the human body, though it must be remarked, that some of
them occur only in exceedingly minute quantity, if indeed they be constant :
oxygen, hydrogen, carbon, nitrogen, phosphorus, sulphur, chlorine, fluorine,
potassium, sodium, calcium, magnesium, iron, silicon, manganese, aluminium,
copper.
Proximate Constituents. The ultimate elements do not directly form the
textures or fluids of the body ; they first combine to form certain compounds,
and these appear as the more immediate constituents of the animal substance ;
at least the animal tissue or fluid yields these compounds, and they in their
turn are decomposed into the ultimate elements. Of the immediate consti-
tuents some are found also in the mineral kingdom, as for example, water,
chloride of sodium or common salt, and carbonate of lime ; others, such as
albumen, fibrin, and fat, are peculiar to organic bodies, and are accordingly
named the proximate organic principles.
The animal proximate principles have the following leading characters.
They all contain carbon, oxygen, and hydrogen, and the greater number also
nitrogen ; they are all decomposed by a red heat ; and, excepting the fatty
and acid principles, they are, for the most part, extremely prone to putrefaction,
or spontaneous decomposition, at least, when in a moist state ; the chief
products to which their putrefaction gives rise being water, carbonic acid,
ammonia, and sulphuretted, phosphuretted, and carburetted hydrogen gases.
The immediate compounds found in the solids and fluids of the human body
are the following.
I. Azotised Substances, or such as contain nitrogen, viz., albumen, blood-
fibrin, muscle-fibrin (or syntonin), casein, globulin, gelatin, chondrin, extrac-
tive soluble in alcohol, extractive soluble in water, salivin, kreatin, kreatinin,
pepsin, mucus, horny matter or keratin, pigment, hsematin, pyin, urea, uric
vi GENERAL CONSIDERATIONS ON THE TEXTURES.
acid, hippuric acid, inosinic acid, sarkin (or hypoxanthin), leucin, tyrosin,
azotised biliary compounds.
II. Substances destitute of Nitrogen, viz., fatty matters (except cerebric
acid), glycogen (or animal starch), animal glucose, sugar of milk, inosit,
lactic, formic, and oxalic acids, certain principles of the bile.
Some of the substances now enumerated require no further notice in a work
devoted to anatomy. Of the rest, the greater number will be explained, as far as
may be necessary for our purpose, in treating of the particular solids or fluids in
which they are chiefly found ; but there are a few of more general occurrence, the
leading characters of which it will be advisable here to state very briefly, viz. :
A. Albuminoid Principles, albumen, fibrin, and casein. Coagulable fibrin
spontaneously, albumen by heat, casein by rennet. Precipitated by mineral
acids, tannic acid, alcohol, corrosive sublimate, subacetate of lead, and
several other metallic salts. When coagulated, not soluble in water, cold or
hot, unless after being altered by long boiling ; insoluble in alcohol ; soluble
in alkalies ; soluble in very dilute and also in concentrated acids ; the solu-
tions precipitated by red and yellow prussiates of potash.
B. Gelatinous Principles, gelatin and chondrin. Not dissolved by cold
water ; easily soluble in hot water ; the solution (at least that of gelatin)
congealing when cold. Precipitated by tannic acid, alcohol, ether, and
corrosive sublimate, and not by the prussiates of potash. Chondrin pre-
cipitated by acids, alum, sulphate of alumina, persulphate of iron, and
acetate of lead, which do not precipitate gelatin.
c. Extractive Matters, associated with lactic acid and lactates. All soluble
in water, both cold and hot ; some in water only ; some in water and
rectified spirit ; some in water, rectified spirit, and pure alcohol.
D. Fatty Matters. Not soluble in water, cold or hot ; soluble in ether
and in hot alcohol.
It has been shown by Mr. Graham,* that chemical substances may be distinguished
into two classes the crystalloid and the colloid which differ in several important
characters. Crystalloid bodies, of which water, most salts and acids, and sugar, may
be taken as examples, have a disposition to assume a crystalline state ; their solutions
are usually sapid, diifluent, and free from viscosity ; they readily diffuse in liquids,
and pass through moist organic membranes or artificial septa of organic matter, such
as parchment-paper. Colloids, on. the other hand, are characterised by low diffusibility
and great indisposition to permeate organic septa, so that when they are associated
with crystalloids, the latter may be easily separated by diffusion through a septum
into another fluid ; i.e., by " dialysis." Colloids are, moreover, generally tasteless ;
they have little or no tendency to crystallize, and their solution, when concentrated,
is always, in a certain degree, viscous or gummy. Among the colloids may be
reckoned hydrated silicic acid, and various hydrated metallic peroxides, also albumen,
fibrin, gelatin, starch, gum, and vegetable and animal extractive matters. Several
substances may exist either in the colloid or the crystalloid condition. In point of
chemical activity the crystalloid appears to be the more energetic, and the col-
loidal the more inert form of matter ; but the colloids possess an activity of their
own, arising out of their physical properties, and especially their penetrability,
by which they become a medium for liquid diffusion, like water itself. Another
characteristic is their tendency to change; the solution of hydrated silicic acid,
for instance, cannot be preserved ; after a time it congeals. In this respect a
liquid colloid might be compared to liquid water at a temperature below freezing,
or to a supersaturated saline solution. This dominant tendency of the par-
ticles of a colloid to cohere, aggregate, and contract, is obvious in the gradual
* Liquid Diffusion applied to analysis, Phil. Trans., 1861.
VITAL PROPERTIES OF THE TEXTURES. vii
thickening of the liquid and its conversion into a jelly ; and in the jelly itself the
contraction still proceeds, causing separation of water, and division into a clot and
serum. Their permeability to fluids, their ready capability of physical changes,
and their comparative chemical inertness, are properties by which colloid bodies seem
fitted to form organised structures, and to take part in the processes of the living
economy. In a recent research,* Mr. Graham has found that silicic acid may
combine both in a dissolved and in a gelatinous state with a variety of very different
fluids without undergoing alteration ; and presuming that the organic colloids are
invested with similar wide powers of combination, he remarks that the capacity of a
mass of gelatinous silicic acid to assume alcohol, or even olein, without disintegration
or alteration of form, and to yield it up again in favour of some other substituted
fluid, may perhaps afford a clue to the penetration of the colloid matter of animal
membrane by fatty and other bodies insoluble in water ; and moreover, that the
existence of fluid compounds of silicic acid of a like nature, suggests the possibility of
the formation of a compound of colloid albumen with olein, soluble also and capable
of circulating with the blood.
The important relation which this new chemical doctrine bears to the constitution
and organic processes of the animal body, has appeared to justify the introduction of
the present notice of it ; for further information the reader is referred to the sources
already cited.
VITAL PROPERTIES OF THE TEXTURES.
Of the phenomena exhibited by living bodies, there are many which, in
the present state of knowledge, cannot be referred to the operation of any
of the forces which manifest themselves in inorganic nature ; they are
therefore ascribed to certain powers, endowments, or properties, which so
far as known, are peculiar to living bodies, and are accordingly named
"vital properties." These vital properties are called into play by various
stimuli, external and internal, physical, chemical, and mental ; and the
assemblage of actions thence resulting has been designated by the term
"life." The words "life" and "vitality" are often also employed to
signify a single principle, force, or agent, which has been regarded as the
common source of all vital properties, and the common cause of all vital
actions.
As ordinary physical forces, such as mechanical motion, heat, electricity, chemical
action, and the like, although differing from each other in specific character and mode
of operation, are nevertheless shown to be mutually convertible and equivalent, and
are held to be but different modifications of one and the same common force or
energy, so it may in like manner come to be shown that vital action is similarly
related to the physical forces as they are related to each other, and is also a mani-
festation, under conditions special to the living economy, of the same common
energy.
1. Assimilative Force. Of the vital properties, there is one which is
universal in its existence among organised beings, namely, the property,
with which, all such beings are endowed, of converting into their own sub-
stance, or " assimilating," alimentary matter. The operation of this pover
is seen in the continual renovation of the materials of the body by nutri-
tion, and in the increase and extension of the organised substance, which
necessarily takes place in growth and reproduction ; it manifests itself,
moreover, in individual textures as well as in the entire organism. It has
been called the "assimilative force or property," " organising force,"
* On the Properties of Silicic Acid and other Analogous Colloidal Substances, Pro-
ceedings of the Royal Society, June 16th, 1864.
viii GENERAL CONSIDERATIONS ON THE TEXTURES.
" plastic force," and is known also by various other names. But in reality
the process of assimilation produces two different effects on the matter
assimilated : first, the nutrient material, previously in a liquid or amorphous
condition, acquires determinate form ; and secondly, it may, and commonly
does, undergo more or less change in its chemical qualities. Such being
the case, it seems reasonable, in the mean time, to refer these two changes
to the operation of two distinct agencies, and, with Schwann, to reserve
the name of "plastic" force for that which gives to matter a definite
organic form ; the other, which he proposes to call " metabolic," being
already generally named " vital affinity." Respecting the last named agency,
however, it has been long since remarked that, although the products of
chemical changes in living bodies for the most part differ from those appear-
ing in the inorganic world, the difference is nevertheless to be ascribed, not
to a peculiar or exclusively vital affinity different from ordinary chemical
affinity, but to common chemical affinity operating in circumstances or con-
ditions which present themselves in living bodies only.
2. Vital Contractility. When a muscle, or a tissue containing muscular
fibres, is exposed in an animal during life, or soon after death, and scratched
with the point of a knife, it contracts or shortens itself ; and the property
of thus visibly contracting on the application of a stimulus is named " vital
contractility," or " irritability," in the restricted sense of this latter terra.
The property in question may be called into play by various other stimuli
besides that of mechanical irritation especially by electricity, the sudden
application of heat or cold, salt, and various other chemical agents of an
acrid character, and, in a large class of muscles, by the exercise of the will,
or by involuntary mental stimuli.
The evidence that a tissue possesses vital contractility is derived, of
course, from the fact of its contracting on the application of a stimulus.
Mechanical irritation, as scratching with a sharp point, or slightly pinching
with the forceps, electricity obtained from a piece of copper and a piece of
zinc, or from a larger apparatus if necessary, and the sudden application of
cold, are the stimuli most commonly applied. Heat, when of certain
intensity, is apt to cause permanent shrinking of the tissue, or "crispation,"
as it has been called, which, though quite different in nature from vital
contraction, might yet be mistaken for it ; and the same may happen with
acids and some other chemical agents, when employed in a concentrated
state ; in using such stimulants, therefore, care should be taken to avoid this
source of deception.
3. Vis Nervosa. The stimulus which excites contraction may be applied
either directly to the muscle, or to the nerves entering it, which then com-
municate the effect to the muscular fibre, and it is in the latter mode that
the voluntary or other mental stimuli are transmitted to muscles from the
brain. Moreover, a muscle may be excited to contract by irritation of a
nerve not directly connected with it. The stimulus, in this case, is first
conducted by the nerve irritated, to the brain or spinal cord ; it is then,
without participation of the will, and even without consciousness, transferred
to another nerve, by which it is conveyed to the muscle, and thus at length
excites muscular contraction. The property of nerves by which they
convey stimuli to muscles, whether directly, as in the case of muscular
nerves, or circuitously, as in the case last instanced, is named the " vis
nervosa. "
4. Sensibility. We become conscious of impressions made on various
parts of the body, both external and internal, by the faculty of sensation ;
DEVELOPMENT OF THE TEXTURES. ix
and the parts or textures, impressions on which are felt, are said to be
sensible, or to possess the vital property of "sensibility."
This property manifests itself in very different degrees in different parts ;
from the hairs and nails, which indeed are absolutely insensible, to the skin
of the points of the fingers, the exquisite sensibility of which is well known.
But sensibility is a property which really depends on the brain and nerves
and the different tissues owe what sensibility they possess to the sentient
nerves which are distributed to them. Hence it is lost in parts severed
from the body, and it may be immediately extinguished in a part, by
dividing or tying the nerves so as to cut off its connection with the brain.
It thus appears that the nerves serve to conduct impressions to the brain, which
give rise to sensation, and also to convey stimuli to the muscles, which excite
motion ; and it is not improbable that, in both these cases, the conductive property
exercised by the nervous cords may be the same, the difference of effect depending on
this, that in the one case the impression is carried upwards to the sensorial part of
the brain, and in the other downwards to an irritable tissue, which it causes to
contract ; the stimulus in the latter case either having originated in the brain, as in
the instance of voluntary motion, or having been first conducted upwards, by an
afferent nerve, to the part of the cerebro-spinal centre devoted to excitation, and then
transferred to an efferent or muscular nerve, along which it travels to the muscle. If
this view be correct, the power by which the nerves conduct sensorial impressions
and the before-mentioned " vis nervosa " are one and the same vital property ; the
difference of the effects resulting from its exercise, and, consequently, the difference
in function of sensorial and motorial nerves, being due partly to the different nature
of the stimuli applied, but especially to a difference in the susceptibility and mode of
reaction of the organs to which the stimuli are conveyed.
DEVELOPMENT OF THE TEXTURES.
The tissues of organised bodies, however diversified they may ultimately
become, show a wonderful uniformity in their primordial condition. From
researches which have been made with the microscope, especially during the
last few years, it has been ascertained that the different organised structures
found in plants, and to a certain extent, also those of animals, originate by
means of minute corpuscles, which, having for the most part a vesicular
structure, have been named cells. These so-called cells, remaining as sepa-
rate corpuscles in the fluids, and grouped together in the solids, persisting
in some cases with but little change, in others undergoing a partial or
thorough transformation, produce the varieties of form and structure met
with in the animal and vegetable textures. Nay, the germ from which an
animal originally springs, so far at least as it has been recognised under a
distinct form, appears as a cell ; and the embryo, in its earliest stages, is
but a cluster of cells produced apparently from that primordial one ; no
distinction of texture being seen till the process of transformation of the
cells has begun.
No branch of knowledge can be said to be complete ; but, even now that
a quarter of a century has elapsed since the promulgation of the cell-
doctrine, there is, perhaps, none which can be more justly regarded as in a
state of progress than that which relates to the origin and development of
the textures, and much of the current opinion on the subject is uncertain,
and must be received with caution. In these circumstances, in order both
to facilitate the exposition, and to explain to the reader more fully the
groundwork of the doctrines in question, we shall begin with a short
x DEVELOPMENT OF THE TEXTURES.
account of the development of the tissues of vegetables ; for it was in conse-
quence of the discoveries made in the vegetable kingdom that the happy
idea arose of applying the principle of cell-development to explain the
formation of animal structures, and they still afford important aid in the
study of that, as yet, more obscure process.
OUTLINE OF THE FORMATION OP VEGETABLE STRUCTURE.
When a thin slice from the succulent part of a plant is viewed under the
microscope, it is seen to consist chiefly or entirely of a multitude of vesicles
adhering together, of a rounded or angular form, and containing various
coloured or colourless matters in their
Fig. i. interior ; these are the elementary
cells (fig. i. ; fig. ir., 12 ). These cells
are so constructed that their walls are
in close apposition, or are separated
only by an intercellular substance,
which, according to Hugo von Mohl,*
has so great a similarity to the sub-
stance of the cell- walls that it is often
impossible, even with the aid of chemical
re-agents, to discover a line of demar-
cation between them. That eminent
Fig. I. NUCLEATED CELLS PROM A phytologist supposes that within what
BULBOUS ROOT ; MAGNIFIED 290 DIA- is commonly called the cell- wall there
METERS (Schwann). exists an extremely delicate mem-
brane, constituting an interior vesicle,
which he names the " Primordial utricle." This is in most cases so closely
applied to the exterior wall as to be undistinguishable ; but in young cells,
and in those of strictly cellular plants, such as the Algse, <fec., during the
whole of their existence it may, according to Mohl, be separated by treating
the tissue with alcohol, or hydrochloric or nitric acid, and then the interior
vesicle appears shrivelled up and separated from the wall of the cavity.
But the reality of the alleged primordial utricle has been called in question,
and the supposed internal membrane is held to be merely the limiting sur-
face of the cell-contents shrunk away from the inside of the containing
cavity, and perhaps somewhat consolidated and defined by the re-agents
employed. Still, whether the cell-contents have a vesicular limiting mem-
brane or not, they originally present a marked contrast in chemical nature
to the containing cell-wall and intercellular substance, and would appear to
fulfil a different purpose in the process of tissue-development, f
Besides such cells, phsenogamous or flowering plants contain tubes,
vessels, and other forms of tissue (fig. u., 4 6 ) ; but a great many plants of
the class cryptogamia are composed entirely of cells, variously modified, it
is true, to suit their several destinations, but fundamentally the same
throughout ; nay, there are certain very simple modes of vegetable existence,
in which a single cell may constitute an entire plant, as in the well-known
green powdery crust which coats over the trunks of trees, damp walls, and
* Die vegetabilische Zelle ; or English translation by Henfrey.
+ See an interesting discussion of this subject by Mr. Huxley in the British and
Foreign Medical Review for 1853.
FORMATION OF VEGETABLE STRUCTURE.
other moist surfaces. In this last case, a simple detached cell exercises the
functions of an entire independent organism, imbibing and elaborating
extraneous matter, extending itself by the process of growth, and continuing
its species by generating other cells of the same kind. Even in the aggre-
gated state in which the cells exist in vegetables of a higher order, each cell
still, to a certain extent, exercises its functions as a distinct individual ; but
it is now subject to conditions arising from its connection with the other
parts of the plant to which it belongs, and is made to act in harmony with
the other cells with which it is associated, in ministering to the necessities
of the greater organism of which they are joint members. These elementary
parts are therefore not simply congregated into a mass, but combined to
produce a regularly organised structure ; just as men in an army are not
gathered promiscuously, as in a mere crowd, but are regularly combined for
a joint object, and made to work in concert for the attainment of it ; living
and acting as individuals, but subject to mutual and general control.
Now the varied forms of tissue found in the higher orders of plants do
not exist in them from the beginning ; they are derived from cells. The
embryo plant, like the embryo animal, is in its early stages entirely formed
of cells, and these of a very simple and uniform character ; and it is by a
transformation of some of these cells in the further progress of development
that the other tissues, as well as the several varieties of cellular tissue itself,
are produced. The principal modes, as far as yet known, in which vegetable
cells are changed, are the following.
1. The cells may increase in size ; simply, or along with some of the
other changes to be immediately described.
2. They alter in shape. Cells have originally a spheroidal or rounded
figure ; and when in the progress of growth they increase equally, or nearly
so, in every direction, and meet with no obstacle, they retain their rounded
form. When they meet with other cells extending themselves in lik&
Fig. II.
Fig. III.
Fig. II. TEXTURES SEEN IN A LONGITUDINAL SECTION OF THE LEAF-STALK OF A
FLOWERING PLANT.
Fig. III. STELLATE VEGETABLE CELLS.
manner, they acquire a polyhedral figure (fig. n. , 1 2 ), by mutual pressure of
their sides. When the growth takes place more in one direction than in
another, they become flattened, or they elongate and acquire a prismatic,
fusiform, or tubular shape (fig. n. , 3 4 3 ). Sometimes, as in the common
rush, they assume a starlike figure, by mutual adhesion of their walls at
xii DEVELOPMENT OF THE TEXTURES.
certain points, whilst they retire from each other elsewhere, so as to leave
radiating branches connected with the points of similar rays from adjacent
cells (fig. in.).
3. The cells coalesce with adjoining cells, and open into them. In this
way a series of elongated cells placed end to end may open into one another
by absorption of their cohering membranes, and give rise to a tubular
vessel.
4. Changes take place in the substance and in the contents of the cells.
These changes may be chemical, as in the conversion of starch into gum,
sugar, and jelly, and in the production of various coloured matters, essential
oils, and the like. Or they may affect the form and arrangement of the
contained substances ; thus, the contents of the cell very frequently assume
the form of granules, or spherules, of various sizes ; at other times the con-
tained matter, suffering at the same time a change in its chemical nature
and in consistency, is deposited on the inner surface of the cell- wall, so as
to thicken and strengthen it. Such " secondary deposits," as they are
termed by botanists, usually occur in successive strata, and the deposition
may go on till the cavity of the cell is nearly or completely filled up (fig. iv.).
It is in this way that the woody fibre and other hard tissues of the plant
are formed. It farther appears that the particles of each layer are disposed
in lines, running spirally round the cell. In place of forming a continuous
layer, these secondary deposits may leave little spots of the cell-wall un-
covered, or less thickly covered, and thus give rise to what is named pitted
tissue (fig. ii., 6 ) ; or they may assume the form of a
Fig. IV. slender fibre or band, single, double, or multiple, running
in a spiral manner along the inside of the cavity, or
forming a series of separate rings or hoops, as in spiral
and annular vessels (fig. n., 7 ). New matter may be
absorbed or imbibed into the cells ; or a portion of
p their altered and elaborated contents may escape as a
SECTION OP LI~GNEOUS secretion, either by transudation through the cell-wall,
CELLS CONTAINING or by rupture or absorption of the membrane. Lastly,
STRATIFIED DEPOSIT, in certain circumstances, cells may be wholly or partially
removed by absorption of their substance.
5. Cells may produce or generate new cells. The mode in which this
takes place will be immediately considered, in speaking of the origin of
animal cells.
FORMATION OF THE ANIMAL TEXTURES.
Passing now to the development of the animal tissues, it may first be
remarked generally, that in some instances the process exhibits an obvious
analogy with that which takes place in vegetables ; for certain of the animal
tissues, in their earlier conditions, appear in form of a congeries of cells,
almost entirely resembling the vegetable cells, and, in their subsequent
transformations, pass through a series of changes in many respects parallel
to some of those which occur in the progress of vegetable development.
Cartilage affords a good example of this. Figures v. and vi., A, are
magnified representations of cartilage in its early condition ; arid whoever
compares them with the appearance of vegetable cells, shown in figures I. and
ii., must at once be struck with the resemblance. Fig. VT., B and c, shows
the subsequent changes on the primary cells of cartilage ; the parietes are
seen to have become thickened by deposit of fresh material, and the mass
FORMATION OF THE ANIMAL TEXTURES.
xiii
Fig. V.
between the cavities is increased. Now, although in certain cases it would
seem that this increase is in part due to deposit of intermediate substance
independently of the coalescence of
thickened cell- walls, yet the process on
the whole may be not unaptly com-
pared with the formation of the hard
tissues of plants from the thickened
sides of vegetable cells. Again, during
the growth of most cartilages the cells
increase in number, new ones being
formed within the old, as happens in
many vegetable structures.
The instance now given, and others
to the same effect, which will be men-
tioned as we proceed, tend to show a
certain fundamental resemblance in the
process of textural development in the
two kingdoms ; but, when we come to
inquire into the various modifications
which that process exhibits in the
formation of particular textures, we encounter serious difficulties. The
phenomena are sometimes difficult to observe, and, when recognised, are
perhaps susceptible of more than one interpretation ; hence have arisen con-
Fig. V. SECTION OP A BRANCHIAL
CARTILAGE OF A TADPOLE, SHOWING
THE EARLY CONDITION OF THE CELLS ;
MAGNIFIED 450 DIAMETERS (Schwann).
Fig. VI. CARTILAGE OF
THE BRANCHIAL RAY
OF A FISH (Cyprinus
erythrophthalmus) IN
DIFFERENT STAGES OF
ADVANCEMENT f MAGNI-
FIED 450 DIAMETERS
(Schwann).
Fig. VI.
flicting statements of fact, and differences of opinion, at present irreconcile-
able, which future inquiry alone can rectify, and which in the mean time
offer serious obstacles to an attempt at generalisation. In what follows,
nothing more is intended than to bring together, under a few heads, the
more general facts as yet made known respecting the formation of the
animal textures, in so far as this may be done without too much anticipating
details, which can only be suitably and intelligibly given in the special
history of each texture.
Structure of Cells. A vegetable cell consists of, 1. a containing wall or
envelope, surrounding and enclosing the other parts, and named, from the
nature of the substance of which it is composed, the cellulose wall (fig. VIL,
a, a) ; 2. the cell-contents fluid, slimy, or of mixed nature (6) ; 3. the
nucleus (c), a rounded corpuscle situated somewhere in the interior, which
however disappears from many vegetable cells when they have reached
maturity. In the nucleus are commonly to be seen one (c) or two (c'),
rarely more, minute spots named nucleoli. Further, some phytologists
maintain that within the cell- wall, and distinct from it, there is a delicate
membrane or film immediately inclosing the cell- contents, the primordial
utricle ; but although the semblance of such an interior inveloping film may
be brought into view by the application of certain re-agents (as at d), its
STRUCTURE OF CELLS.
existence as a natural structure is (as already remarked, p. x) at best but
doubtful.
Fig. VII. Fig. VIIT.
I -
Fig. VII. DIAGRAM OP VEGETABLE CELLS.
a, a', cellulose wall ; 6, cell-contents ; c, c', nucleus ; d } contents shrunk away from the
cell-wall.
Fig. VIII. DIAGRAM OF ANIMAL CELLS (OP CARTILAGE).
a, a', capsule ; 6, cell-contents ; c, nucleus ; d y cell-contents shrunk away from the
capsule.
Certain animal cells have a structure conformable throughout with that
just indicated as belonging to vegetable cells. Thus, the cartilage-cell has
an outer envelope or capsule (fig. vin., a, a'), not indeed composed of cellulose
but of animal matter, comparable nevertheless with the vegetable cellulose-
wall, and in like manner continuous with the intercellular substance. The
cell-contents (6), nucleus (c), and nucleolus or nucleoli, correspond. Finally,
it has been held that there is here also a fine interior envelope correspond-
ing to the primordial utricle of the vegetable cell, and it may be added that
the agreement extends to the doubt entertained of the reality of such a
membrane in either case.
But many animal cells have no exterior capsule answering to the cellulose
vegetable cell- wall, and accordingly represent only the parts of the vegetable
cell which are within that enclosure ; that is, the nucleus and the mass of
cell-contents. The chyle-, lymph-, and pale blood-corpuscles, the mucus-
and salivary corpuscles, and the cells that first appear in the embryo, may
be adduced as examples. Some cells of this description have or acquire a
fine membranous envelope closely investing their surface, and corresponding
to the supposed primordial utricle ; but many of them appear to be naked,
and to consist of a nucleus surrounded by a mass of soft matter the so-
called cell-contents often containing solid granules which are held together
by a tenacious substance. In these cases the matter at the surface is more
condensed than in the interior, where not unfrequently it is more or less
fluid. There is moreover a well-defined superficial outline, but there is
wanting an internal contour-line marking oif an envelope distinct from the
contained substance. Such bodies, it is true, may sometimes show appear-
ances indicating the presence of an envelope, when they are treated with
certain chemical re-agents ; but in such cases the apparent envelope may be
produced by the action of the substances employed. At the same time, it
must be borne in mind that various cells which in their young state have no
envelope, distinctly acquire one at a later stage of their existence ; and
this occurrence is especially to be observed in cells which are destined to
form consistent structures, such as epidermis and epithelium. In these
PRODUCTION OF CELLS. xv
cases the younger and more deeply seated cells have no envelope, but acquire
one before taking their place in the more superficial firm layers.*
The envelope, when present, is thin, transparent, homogeneous, flexible,
and permeable to fluids. The contents differ greatly in different cells ; but
in those that form the first foundation of the tissues and organs in the embryo,
in young cells generally, and in some cells throughout their whole existence,
the contained matter is a peculiar semifluid substance, named %)rotoplasm,
and granular particles, mostly of a fatty nature, densely or sparingly mixed
with it. The protoplasm is transparent, colourless, not diffluent, but
tenacious and slimy, and under high magnifying powers is seen to contain
very fine molecules. In chemical properties it agrees generally with
albuminoid bodies, but in many animal cells it doubtless also includes other
organic principles, especially fat and glycogenous or amyloid matter. The
protoplasm is endowed with remarkable powers of contraction and motion,
to be afterwards referred to. But, while certain cells, as already said,
retain their primary constitution, others acquire very different matters :
many contain mucus ; the fat-cells are filled with oil ; the cells of glands
include the characteristic ingredients of the secretions ; the substance of the
red blood-cells is coloured, and certain cells are filled with particles of pig-
ment. Very commonly in vegetable cells the protoplasm occupies but a
small part of the space within, while the remainder is filled with watery
fluid with which the protoplasm does not mingle.
Free Nuclei. Besides the bodies which have been called cells, corpuscles
having all the characters of cell-nuclei exist abundantly in various tissues,
such as the membranous walls of the capillaries, the sheaths of nerve-fibres,
muscular fibres, &c. But in some of these cases it is obvious, in others
highly probable, that the nuclei are associated with a certain amount of
protoplasm, although not in the usual mass and form of a cell.
Production of Cells. Consistently with the present state of knowledge
on this subject, the following may be assigned as the several modes in which
cells and nuclei are observed to be produced in the animal system ; but
while the process varies in outward conditions in each of these cases, it can
scarcely be doubted that it will prove to be intrinsically and fundamentally
the same in all.
a. In the Ovum. The ovum may be regarded as a cell derived from
the parent. In mammalia (fig. ix., A), it has a transparent but stout
external membrane (a) ; within this is the yelk (6), corresponding to the
cell-contents ; in the yelk is the germinal vesicle (c), including the germinal
spot (macula germinativa), which are comparable, respectively, to the
nucleus and nucleolus. The yelk consists originally of fine molecular
particles held together in a transparent tenacious matrix of protoplasm ;
and when once fertilisation has taken place, the yelk-mass undergoes a
process of subdivision or " segmentation," whereby it is fashioned into
* The existence of animal cells destitute of envelope, although more insisted on of late
years, has been all along recognised in the study of cell-development, and was expressly
pointed out by Schwann himself (Microscopische Untersuchungen, &c.,p, 209). It has
appeared to some that another name should be used to designate bodies which thus exist
in a naked non- vesicular form. Briicke proposes to call them " elementary organisms," a
term too cumbrous for use ; as the first " shaped " products of organisation which appear
in the development of all but the lowest organised beings, they might be named " proto-
plasts," or, as that name has been already used in a widely different sense "monoplasts;"
but, after all, seeing the universal currency of the term " cell," it is probably most con-
venient and best to adhere to it, with the understanding that in many cases it is used in a
conventional sense.
xvi
PRODUCTION OF CELLS.
cells, progressively increasing in number, which combine to form the first
material substratum of the tissues and organs of the embryo, and are hence
termed " embryonic cells."
The outline of the process is this. The germinal vesicle disappears ;
the 3 7 elk shrinks somewhat together, then separates into two halves (B) ;
the first two segments divide each again into two (c), and the binary
Fig. IX. DIAGRAMMATIC FIGURES TO ILLUSTRATE THK FORMATION OF CELLS WITHIN THE
MAMMALIAN OVUM BY SEGMENTATION OF THE YELK ; MAGNIFIED.
a, external membrane ; b, yelk ; c, germinal vesicle containing the germinal spot ; d,
embryonic cells further magnified.
division thus goes on (D, E,) pretty regularly, until a large group of small
segments is produced (r). These final segments are the embryonic cells (d) ;
they probably have no distinct, separable envelope ; but, like other naked
cells, they are formed of a nucleus and body of protoplasmic matter. The
nucleus is a globule of soft pellucid substance ; it may not be always dis-
coverable in the earlier segments, being hidden by the opaque granular
mass ; but it soon comes into view, and it seems to play an important part
in the formation of the cells. The nucleus in fact appears to initiate the
process of division, by itself dividing into two halves, which, speedily
acquiring full size, serve as two centres of attraction, round each of which
separately the yelk-substance is gathered, and thus parted into two new
segments. Possibly the substance of the vanishing germinal vesicle and
spot may give rise to the first nucleus.
Fig. X. DIVISION OF THE YELK of ASCARIS.
o (from Kolliker), ovum of Ascaris nigrovenosa ; D and E, that of Ascaris
A, B,
acuminata (from Bagge).
PRODUCTION OF CELLS. xv ji
The formation of cells by segmentation of the yelk may be traced with comparative
ease in the ova of many invertebrata. The accompanying figures represent the several
stages of the process in small species of the ascaris worm. Figures A, B, and o are
from the Ascaris nigrovenosa, as observed by Kolliker. He found that, after the
germinal vesicle had disappeared, a new nucleus with nucleolus was formed in its
place. The segmentation then goes on as in the mammalian ovum, but the nuclei
are visible from the first ; and from appearances, such as those seen in the lowermost
segments of A and B, it seems probable that the division of the nucleus is preceded by
that of the nucleolus.
I may remark that I once observed the ovum of the ascaris under the microscope
whilst one of the large segments was actually undergoing division. There was first a
very obvious heaving motion among the granules throughout the whole mass ; then
ensued a constriction at the circumference, which, proceeding inwards, soon com-
pleted the division ; but ail this time the nuclei were quite hidden by the enveloping
granular matter.
In some animals the segmentation process affects only a part of the yelk.
6. Division of free Cells. Essentially the same process of fissiparous
propagation by which the cells are multiplied within the ovum continues to
take place in the embryonic cells at future
stages, and in their descendants in the pig j^
organs and fluids of the body throughout
life. The steps of the operation have been
best observed and proved in the colourless
blood-corpuscles, but it takes place in various
other cells (fig. XL).
1. Into two. The body of the cell is ob-
served to be somewhat lengthened, and its
nucleus divided into two ; a constriction then Fig. XI. COMMENCEMENT, Pno-
begins in the middle and proceeds until the GRESS, AND RESULT, or Divi-
substance of the cell is parted into two halves,
each of which contains a nucleus. There can
be little doubt that here also the division begins with the nucleus. The
colourless blood-corpuscle we presume to have no proper cell-wall, but if,
as some believe, an envelope or primordial utricle is present, it is also
involved in the division.
2. Into more than two. The division is usually into two, as above
described, but Remak has observed instances in the frog larva of cells
dividing into as many as five or six new cells ; that is, after the nucleus
had divided in a corresponding way. The difference in this modification
of the process may simply be that whilst in the preceding case the two
halves of the divided cell part from each other, and the resulting new cells
undergo fresh subdivision solitarily, they in the present case remain asso-
ciated in a group. Perhaps the formation of pus-corpuscles from connective
tissue-corpuscles, as described by Virchow, may be an instance of this
kind. Where the swollen primitive corpuscle acquires a distinct cell-
membrane or capsule which incloses its progeny, the case comes to resemble
the so-called " endogenous " propagation, as in cartilage, to be next
described.
c. Division of inclosed Cells An example of this is afforded by carti-
lage. The cells in that tissue are surrounded by an outer capsule, which
is continuous, or at least coherent, with the substance of the matrix
(fig. xii. , A). Here, as in the previous cases, there is first a division of
the nucleus into two; this is followed by cleaving of the cell-body like-
wise into two, and thus two young cells are formed from a parent one.
b
XV111
PRODUCTION OF CELLS.
So far the process is the same as before ; but now a species of capsule is
formed round each of the young cells (B), whilst the old one enclosing
them becomes blended with the intercellular matrix, and is no longer
traceable (c).
Fig. XII.- IDEAL PLAN OF THE MULTIPLICATION OF CELLS OF CARTILAGE.
A, cell in its capsule ; B, divided into two, each with a capsule ; C, primary capsule
disappeared, secondary capsules coherent with matrix ; D, tertiary division j E, secon-
dary capsules disappeared, tertiary coherent with matrix.
The new cells, in turn, divide in the same way, so as to make a
group of four, each of which is surrounded by its own capsule (D), whilst
the capsules of the first descent (secondary) blend with the matrix (E) like
their predecessor. In certain cases the whole series of capsules may
remain visible ; in others, and especially in morbid conditions, the young
capsules may not be formed, or may all disappear, leaving the young cells
surrounded by the still conspicuous original capsule, like the yelk-segments
in the ovum.
The multiplication of cells in the ovum and in cartilage, seeing that it takes place
within an enclosing envelope, has been named " endogenous ; " but it will be per-
ceived that the difference between this and the division of a free cell is unimportant.
d, Multiplication of Nuclei in Cells. Irregularly shaped cells have been
found in the medullary cavities of bone (Robin and Kolliker), containing
many nuclei, and such cells afford an example of the multiplication of
nuclei within a cell without separation into new cells. Other multi-
nucleated cells are formed in the spleen and pass into the blood of the
splenic vein (Kolliker); but if these eventually divide into uninucleated
cells, as seems most probable, the case falls under 6, 2.
e. Multiplication of free Nuclei. Bodies having the characters of nuclei
and designated as such, commonly make their appearance in large numbers
where growth or new formation of tissue is going on. There can be little
doubt that these are produced by division of previously existing nuclei,
uninclosed in cells but yet originally descended from cells, and probably
associated with an inconspicuous amount of shapeless protoplasm. The new
nuclei may continue in the same condition as those from which they imme-
diately sprung, or it may happen that the protoplasm grows and accumulates
round the groups of multiplying nuclei, each of which assumes its distinct
share, and there thus results a group of new cells. The nuclei lying on the
MOTIONS OF THE PROTOPLASM.
xix
walls of the capillary vessels have been observed to multiply in this way in
the formation of new (morbid) growths, as is shown in fig. xiu.
Fig. XIII. CAPILLARY VESSEL FROM A FIBROID TUMOUR ; MAG- Fig. XIII.
NIFIED (adapted from C. 0. Weber, Virch. Arch. 1864).
a, a, nuclei on the wall of the capillary ; 6, nucleus after
division into two ; c, group of nuclei surrounded by protoplasm ;
d, new cells ; e, cells of connective tissue.
Seeing the successive generations of cells which proceed from
a single one in the ovum, and the propagation of cells in a
similar manner which occurs at after-periods, physiologists have
been naturally led to look to the ovum for the original source
to which all succeeding cells in the economy might be traced
back ; and, as that body is itself derived from the parent organ-
ism, it is conceived that a peculiar germinative matter is handed
down from parent to offspring, and, receiving an impulse by
fecundation, begins in the ovum the series of assimilative and
reproductive actions which is afterwards continued throughout
life. Seeing, moreover, that throughout all these operations the
nucleus takes the first apparent step in the propagation of cells,
and by itself increases and multiplies, that body may not un-
reasonably be regarded as the original depositary and sub-
sequent representative of the germinative matter in its
most characteristic type, although, no doubt, the protoplasm of the primary cell-
contents is, in its degree, endowed with the same property. According to this view,
all cells in the animal economy are derived from pre-existing cells, and all are to
be referred back through preceding generations to the ovum. Schwann, on the other
hand, maintained that cells may arise altogether independently of pre-existing cells,
and that in animals this was actually the most prevalent mode of cell-production.
He conceived that cells are formed out of a soft or liquid organisable matter, which
he named " cytoblastema," or simply " blastema," and which in animals that have a
circulating blood is derived from that source. The blastema might be contained in
cells, lodged in the interstices of cells and tissues, or deposited on the surface of
growing parts ; and cells might arise in any of these situations, viz., in previously
existing cells, or in the interstitial and free blastema. As to the steps of the process
of formation, Schwann adopted and applied to animal cells the account given by
Schleiden of cell-genesis in vegetables. According to Schleiden, nuclei are first
formed by aggregation of matter round nucleoli which appear in the cytoblastema,
and a cell-wall is produced by deposition and condensation of fresh matter on the
nucleus, which he regarded as the generator of the cell, and therefore named the
" cytoblast." Among later observers who deny the uninterrupted descent of all cells
from the ovum, may be mentioned M. Robin, who believes that the embryonic cells
derived from the ovum do not generate secondary cells, but suffer complete dissolu-
tion, at the same time that fresh nuclei are independently formed in their insterstices
from the dissolved substance.
The doctrine of independent cell-formation, which, in contradistinction to derivation
from previously existing parent-cells, it has been proposed to call " equivocal cell-
generation," has greatly lost ground since it was first promulgated ; and perhaps it
must be abandoned as regards cell-formation in the higher animals. At the same
time, undue weight must not be allowed to the natural d priori argument against it
as a case of spontaneous generation. It must further be borne in mind that in
certain lichens, algae and fungi, spores entirely constituted as cells arise, not indeed
independently of a parent organism, but to all appearance not immediately from pre-
existing cells or nuclei.
Motion of the Protoplasm in Cells. In the cells of the Vallisneria, Chara,
and various other plants, when exposed under the microscope, the green
62
xx MOTIONS OF THE PROTOPLASM.
coloured grains (of chlorophyll) and other small masses and corpuscles con-
tained in the cavity, are seen to be moved along the inside of the cell- wall
in a constant and determinate direction. This phenomenon appears to be
of very general occurrence in the vegetable kingdom, although the movement
does not always go on with the same regularity as in the instances cited.
It is obviously due to a layer of protoplasm on the inner surface of the
cell-wall, which enters into a peculiar flowing or undulating motion and
trails the passive corpuscles along with it; but how the motion of the
protoplasm itself is produced is not at all understood.
Motions are also observed in animal protoplasm ; cells in form of nucleated
protoplasm-masses of irregularly stellate or jagged outline, which lie in
the areolar tissue and are called connective tissue-corpuscles, and similar
bodies in the substance of the cornea, have been noticed slowly to change
figure whilst under observation (in the tissues of the recently killed frog),
shrinking in at one part of their uneven contour and extending their soft
substance at another. The effect seems to be due to a contractile property
of the protoplasm comparable to the contractility of muscular substance ;
for Kiihne* has found that the substance of these protoplasm bodies con-
tracts under the electric stimulus, and contractions may be excited in the
corneal cells through the medium of fine nerves which are distributed to
them, and this both by mechanical and electrical stimulation. Now the soft
transparent matter named te sarcode " which constitutes the bodies of the
amoeba and actinophrys, and the animal part of the foraminifera and
other allied organisms of simple nature, exhibits similar retractile and
extensile movements, and may also be made to contract by electrical excite-
ment ; and accordingly it is reckoned as an example of protoplasm by some
recent observers of authority and designated by that name. It is further
to be noted, however, that the varied movements of the amoebine animals
are very generally accompanied by a flowing of fine particles to and fro in
their pellucid substance, as if there were a thinner and more diffluent por-
tion confined within the more firm exterior part. The movement of the
fluid matter, and consequent flow of the particles carried by it, have been
ascribed by some observers to an impulse caused by the contractions of the
firmer portion, but there are cases in which this explanation is hardly
sufficient, and the point remains in doubt.
To the same class of phenomena are probably to be referred the remark-
able movements observed in the pigment-cells of the frog's skin, which have
been so lucidly investigated by Professor Lister. t In these ramified cells
the dark particles of pigment are at one time dispersed through the whole
cell and its branches, but at another time they gather into a heap in the
central part, leaving the rest of the branched cell vacant, but without
alteration of its figure. In the former case the skin is of a dusky hue ; in
the latter, pale. The phenomenon is probably due to some kind of motion
of the protoplasm, although it must be admitted that Mr. Lister has
adduced arguments of considerable weight to prove that there is some
impulse operating directly on the particles, and that they move indepen-
dently of the surrounding matter, which he considers to be fluid. Like the
movements of the protoplasm, the aggregation of the pigment molecules can
be excited through the nerves, both mechanically and electrically.
Lastly, the pale blood-corpuscles and other similarly constituted cells of
* Untersuchungen iiber das Protoplasma und die Contractilitafc. 1864.
t Phil. Trans. 1858.
CELLS IN RELATION TO TISSUE-FORMATION. xxi
common occurrence exhibit changes of figure and movements of an amoebine
character which seem naturally to be referred to the present head.
The fact above mentioned, that these movements of cells may be excited
by stimulation of the nerves, is especially worthy of note, in as much as it
proves that operations effected in and by cells are more or less under the
governance of the nervous system. Moreover, the well-known influence of
mental states over the secretions, and the effects resulting from ex-
perimental stimulation of the nerves of secreting glands, although doubtless
due in part to changes in the blood-vessels, seem to show that this subjec-
tion to the nervous system extends even to the chemical and physical
operations which take place in secreting cells. A curious and interesting
observation in proof of this is adduced by Kolliker. He found that the
light of the firefly, fampyriSf is emitted from cells in which albuminoid
matter is decomposed with production of urate of ammonia, and that the
emission of light could be brought on or rendered more vivid by electrical
and other stimuli operating through the nerves.
The well-known tremulous movement which so often affects minute
particles of matter, is not unfrequently observed in the molecular contents
of cells ; but this phenomenon depends simply upon physical conditions, and
is of a totally different character from the motions of the protoplasm above
referred to.
Of Cells in Relation to the Formation of Textures. In a certain sense it
might be said that the foundation of all the textures and organs of the
body is formed of cells ; for in the early embryo all the different parts of
the body, so far as they are characterised by form and position, are made
up of embryonic cells ; but how the different and special characters of the
fully organised textures are produced is still a matter of no little uncer-
tainty. No doubt certain textures in their mature condition are composed
of cells, which, on the supposition of continuous cell-generation, must be
the progeny of the embryonic cells, although modified in character to suit
them to their special destination. The epidermis, the several varieties of
epithelium, and the plain or non-striated muscular tissue are examples of
this. Other textures or textural elements are not made up of cells or
formed immediately from cells, as, for example, the fibres of connective
tissue, which are produced in intercellular substance. But there remain
cases of tissue-formation in which, whilst it is generally admitted that cells
or nuclei take part, it is not agreed to what extent or in what precise
mode these bodies share in the process : the development of the fibres
of voluntary muscles and nerves affords an illustration of this, as will be
afterwards shown in its proper place. Accordingly, the reasonableness of
certain limitations and qualifications of the doctrine of tissue-development
from cells has been recognised by judicious histologists, even from its first
promulgation.
Of the changes which cells or their elements undergo in the formation of
tissues, or afterwards in the exercise of their functions when constituting
part of the living organism, the following are what may be considered as
best ascertained ; and it is to be observed that the same cell may undergo
more than one of the changes indicated.
1. Cells may increase in size and change their figure. When a cell
grows equally or nearly so in all directions, it preserves its globular shape ;
but more commonly the growth is greater in one dimension than in another,
and then the cell becomes flattened, in which case it may remain as a
round disk or change into an oval, fusiform, or strap-shaped figure. When
CHANGES OF CELLS IN THE
Fig. XIV.
growing cells meet one another, they generally become angular or poly-
hedral ; and this change may be combined with elongation into the pris-
matic or flattening into the tabular form, as exemplified in the columnar
and scaly varieties of epithelium. A more remarkable change of figure
occurs in those instances where a cell sends out branches at various
points of its circumference, as happens with
certain varieties of pigment-cells (fig. xiv.),
connective tissue corpuscles, and nerve-cells.
Of course, when the changes of figure are accom-
panied by an absolute increase in size, there must
be assumption of new matter by the cell. The
nucleus seems to be less subject to alteration in
s-ize and shape. It may grow somewhat larger
as the cell increases, especially at first ; thus it
enlarges and flattens in epithelium-cells. In
the cells of non-striated muscle it becomes oblong
or rod-shaped. Sometimes it disappears, as in
the flattened cells of the cuticle.
2. Whilst the above -described changes of figure
are going on, the cell- wall may acquire increased
density and strength ; and in a flattened cell,
when much extended, the opposite sides may co-
here so as to convert it into a scale. The thicken-
ing of the cell-membrane may take place by
deposition of new matter on its inner surface, as
in vegetable cells, or on the outside, as is pro-
bably the case in the partial thickening of the
cell-wall in certain forms of intestinal epithelium ;
but there are cases in which it is difficult to
determine in what way the change is effected. The substance of a cell thus
condensed may have changed more or less in chemical nature, as in the
cuticle, where the cells, while deep-seated and recently formed, are soluble
in acetic acid, but as they rise to the surface lose this property and acquire
a horny character.
3. Changes may take place in the cell- contents. Granular matter in
cells may be dissolved and consumed, as is well seen in the formation of
blood- corpuscles from granular cells in the oviparous vertebrata. On the
other hand, new matters may appear, as fat and pigment within the adipose
and pigmentous cells, and the peculiar constituents of certain secretions in
the cells of secreting organs, in which last case the cells may burst and dis-
charge their contents. Lastly, the process may take on more of a plastic
and organising character, as in the generation of young cells, already
described, and the formation of the spontaneously moving bodies named
spermatozoa, which are produced from the nuclei of cells.
These plastic changes are equally unexplained with the other alterations of form
and structure which accompany the production and metamorphoses of cells. As
regards the changes in the quantity and chemical nature of the contained matter, it
may be remarked, that the introduction of new matter into a cell is so far a phe-
nomenon of imbibition, and, as such, must be to a certain extent dependent on the
endosmotic effect produced by the substance already within the cell, and on the
comparative facility with which the matter to be introduced is imbibed and transmitted
by the permeable cell-wall. Some substances, moreover, being more readily imbibed
than others, the quality as well as the quantity of the imbibed material will be so far
Fig. XIV. RAMIFIED AND
FUSIFORM CELLS, FROM THE
TISSUE OF THE CHOROID
COAT OF THE EYE ; MAG-
NIFIED 350 DIAMETERS
(after Kolliker).
a, cells with pigment ;
b, colourless fusiform cells.
FORMATION OF TISSUES. xxiii
determined by the same circumstances. Thus, uric acid, known to be present in
minute quantity in the blood, is gathered up by the cells of the kidneys ; and other
chemical compounds existing in the circulating fluid may be segregated in Hke
manner by cells, to be discharged by excretion. Also, in the converse operation of
absorption of aliment, the cells of the intestinal epithelium become charged with
particles of fat. But, Avhile an alteration in the contents of a cell may be thus
brought about by the imbibition of one kind of matter in preference to another, the
contained substance may be also changed in its qualities by a process of conversion
taking place within the cell.
4. Cells ultimately present differences in their relations to each other.
a. They may remain isolated, as in the instance of the corpuscles of blood,
chyle, and lymph, and those formed in certain secretions.
b. They may be united into a continuous tissue, by means of a cementing
intercellular substance ; the epithelium and cuticle, the nails and hairs,
afford instances of this. In cartilage, where this occurs, the capsules of the
cells may become more or less blended with the intercellular substance.
c. The parietes of neighbouring cells meet at particular points, and,
absorption taking place, their cavities become united. It is supposed that
ramified cells may thus open into one another ; and Schwann conceives that
the networks of capillary vessels originate in this way.
Intercellular Substance. Of the matter which lies between cells the
intercellular substance and its relation to them, it may be observed that
sometimes it is in very small quantity, and seems merely to cement the
cells together, as in epidermis and epithelium ; at other times it is more
abundant, and forms a sort of matrix in which the cells are imbedded, as in
cartilage. It is homogeneous, translucent, and firm in most cartilages, and
pervaded by fibres in yellow cartilage. In connective tissue it consists of
fibres, with soft interstitial matter, which is scanty in the denser varieties,
but abundant in the lax tissue of the umbilical cord ; in bone the inter-
cellular substance is calcified and mostly fibrous. As to the production of
the intercellular substance, there can be little doubt that in cartilage it is
derived from the cells. Formed as capsules round the cells by excretion
from their surface, or by conversion of their proper substance, and being
blended into a uniform mass, it accumulates while the cells multiply, and
while fresh material is supplied to them from the blood, which they convert
into chondrinous substance. Kolliker supposes that, in like manner,
simple membrane, such as the membranes propriw of gland-ducts, may be
produced by excretion from a series of cells ; in which case such membranes
would come under the same description as intercellular substance. The
source of the intercellular substance is in other cases not so apparent, but
it may be presumed that the cells have some influence in its nutrition and
maintenance.
From what has been said it will be obvious that cells and nuclei play an important
part in the growth of textures, and probably in nutrition. The former process is
usually accompanied by a great multiplication of cells or nuclei, the peculiar consti-
tuent of which the protoplasm seems to be specially endowed with the faculty of
propagation by division, and of increase by appropriating and converting new matter.
It is conceivable that in this way it may serve for the extension of growing tissue
and the development of structural elements from the crude materials of growth.
Again, in the nutrition of a mass of tissue the crude material may undergo preparation
by the cells or nuclei that lie in the insterstices of the structure.
The existence of this protoplasmic germinative substance is very general, perhaps
indeed universal, in the animal and vegetable kingdoms. But, M'hilst in the great
xxiv NUTRITION OF THE TEXTURES.
majority of organic beings it assumes the form of a nucleated cell (protoplast, or
monoplast), as the first condition of their organised structure, in simpler modes of life
and organisation it is not subject to the same limitation of form and mass. In the
mycetozoa (myxomycetes), a curious tribe, heretofore mostly reckoned among the
fungi, but standing as it were in the debateable ground between the animal and
vegetable kingdoms, the protoplasm is extended into reticular masses, or irregularly
anastomosing trains, spread over the surface of bark and other bodies to which it
parasitically clings ; whilst in vibrios and some other infusorial animalcules of the
simplest kind, it appears as fine molecular particles ; but it is most probably derived
from parents in all instances, however minute and apparently insignificant these
may be.
Professor Beale proposes to distinguish the matter of organised bodies into two kinds,
viz., " germinal matter " which comprehends the active matter of cells and nuclei,
and appears to correspond with what has been already described as protoplasm and
" formed material," under which term he includes all the structural elements and
intercellular substances lying outside and between cells, the cell-wall itself when
present, and certain products, not germinative, which may be included in the cell-
contents. " Germinal matter " grows and increases, and is converted into " formed
material;" and all " formed material" has passed through the condition of " germinal
matter." In nutrition, according to Dr. Beale, " pabulum does not pass through the
cell- wall to become altered by the action of the cell, but certain of its constituents are
converted into germinal matter, the living substance, which becomes tissue, or is
changed into substances which form the constituents of the secretions." Formed
material may be endowed with peculiar and important properties, but is destitute of
the power of producing matter like itself, "it has no power to produce structure or to
alter itself." * I presume it is not meant by this to imply that " formed material " is
incapable of undergoing further organisation ; for otherwise the proposition would be
in contradiction to well-known facts, such as the formation of fibres in the matrix of
cartilage, &c.
Professor Bennett considers that organisation begins with molecules or granules of
various composition and endowments. These are of two kinds histogenetic, formed
by precipitation from fluids, &nd.histolytic, derived from the disintegration of previously
formed tissues. Molecules of disintegration may in peculiar circumstances become
the basis of matter which undergoes development, so that histolytic or disintegration
particles of one period become the histogenetic or formation molecules of another.
Certain molecules are endowed with the power of active movement, and the motions
in cells and tissues depend upon them ; they are mutually attracted by a molecular
force, and thus unite to produce cells and higher forms of tissue. t
Molecules and granules are, no doubt, more elementary forms of organisable
substance than cells ; still it is matter of observation that in the early embryo and in
the production of certain tissues, these particles in the first instance unite to form
cells. This, Dr. Bennett by no means denies, only he regards the formation of cells
as of subordinate moment in the general process of organisation. For my own part
I am disposed to think that in the process of organisation, as distinguished from its
result, the cognisable form and mass of the organisable material, whether as cell or
molecule, are of altogether subordinate consideration to the nature of its substance.
NUTRITION AND REGENERATION OF THE TEXTURES.
Nutrition. The tissues and organs of the animal body, when once em-
ployed in the exercise of their functions, are subject to continual loss of
material, which is restored by nutrition. This waste or consumption of
matter, with which, so to speak, the use of a part is attended, takes place
in different modes and degrees in different structures. In the cuticular
* On the Structure of the Simple Tissues of the Human Body, &c., 1861 ; and Archives
of Medicine for 1862.
f For a brief but lucid exposition of his views on this subject, see Dr. Bennett's paper
On the Molecular Theory of Organisation, as given in abstract in the Proceedings of the
Royal Society of Edinburgh for the 1st of April, 1861.
NUTRITION OF THE TEXTURES xxv
textures the old substance simply wears away, or is thrown off at tha sur-
face, whilst fresh material is added from below. la muscular texture, on
the other hand, the process is a chemical or cheinico-vital one ; the func-
tional action of muscle is attended with an expenditure of moving force,
and a portion of matter is consumed in the production of that force ; that
is, it undergoes a chemical change, and being by this alteration rendered
uufit to serve again is removed by absorption. The amount of matter
changed in a given time, or, in other words, the rapidity of the nutritive
process, is much greater in those instances where there is a production and
expenditure of force, than where the tissue serves merely passive mechanicil
purposes. Hence, the bones, tendons, and ligaments are much less wasted
in exhausting diseases than the muscles, or than the fat, which is consumed
in respiration, and generates heat. Up to a certain period, the addition of
new matter exceeds the amount of waste, and the whole body, as well as
its several part:?, augments in size and weight : this is " growth." When
maturity is attained, the supply of material merely balances the con-
sumption ; and, after this, no steady increase takes place, although the
quantity of some matters in the body, especially the fat, is subject to
considerable fluctuation at all periods of life.
It would be foreign to our purpose to enter on the subject of nutrition in
general j we may, however, briefly consider the mode in which the renova-
tion of substance is conceived to be carried on in the tissues.
The material of nutrition is immediately derived from the plasma of the
blood, or liquor sangutnis, which is conveyed by the blood-vessels, and
transudes through the coats of their capillary branches ; and it is in all cases
a necessary condition that this matter should be brought within reach of
the spot where nutrition goes on, although, as will immediately be explained,
it is not essential for this purpose that the vessels should actually pass into
the tissue.
In' cuticle and epithelium, the nutritive change is effected by a con-
tinuance of the process to which these textures owe their origin. The
tissues in question being devoid of vessels, nutrient matter, or blastema, is
famished by the vessels of the true skin, or subjacent vascular membrane ;
this matter is appropriated by young cells derived most probably from pre-
existing ones. These new cells enlarge, alter in figure, often also in chemical
nature, and, after serving for a time as part of the tissue, are thrown off at
its free surface.
But it cannot in all cases be so clearly shown that nutrition takes place
by a continual formation and decay of the structural elements of the tissue ;
and it must not be forgotten, that there is another conceivable mode in
which the renovation of matter might be brought about, namely, by a mole-
cular change which renews the substance, particle by particle, without
affecting the form or structure ; by a process, in short, which might be
termed "molecular renovation." Still, although conclusive evidence is
wanting on the point, it seems probable that the crude material of nutrition
first undergoes a certain elaboration or preparation through the agency of
cells and nuclei disseminated in the tissue ; which may serve as centres of
assimilation and increase, as already explained.
Office of the Vessels. In the instance of cuticle and epithelium, no vessels
enter the tissue, but the nutrient fluid which the subjacent vessels afford
penetrates a certain way into the growing mass, and the cells continue to
assimilate this fluid, and pass through their changes at a distance from, and
independently of, the blood-vessels. Whether, in such cases, the whole of the
xxvi NUTRITION OF THE TEXTURES.
residuary blastema remains as intercellular substance, or whether a part is
again absorbed into the vessels, is not known. In other non- vascular
tissues, such as articular cartilage, the nutrient fluid is doubtless, in like
manner, conveyed by imbibition through their mass, where it is then
attracted and assimilated. The mode of nutrition of these and other non-
vascular masses of tissue maybe compared, indeed, to that which takes
place throughout the entire organism in cellular plants, as well as in polypes
and some other simple kinds of animals, in which no vessels have been
detected. But even in the vascular tissues the case is not absolutely
different ; in these, it is true, the vessels traverse the tissue, but they do
not penetrate into its structural elements. ThuS the capillary vessels of
muscle pass between and around its fibres, but do not penetrate their
inclosing sheaths ; still less do they penetrate the fibrillse within the fibre ;
these, indeed, are much smaller than the finest vessel. The nutrient fluid,
on exuding from the vessels, has here, therefore, as well as in the non-
vascular tissues, to permeate the adjoining mass by transudation, in order to
reach these elements, and yield new substance at every point where renova-
tion is going on. The vessels of a tissue have, indeed, been not unaptly
compared to the artificial channels of irrigation which distribute water over
a field ; just as the water penetrates and pervades the soil which lies be-
tween the intersecting streamlets, and thus reaches the growing plants, so
the nutritious fluid, escaping through the coats of the blood-vessels, must
permeate the intermediate mass of tissue which lies in the meshes of even
the finest vascular network. The quantity of fluid supplied, and the dis-
tance it has to penetrate beyond the vessels, will vary according to the
proportion which the latter bear to the mass requiring to be nourished.
We have seen that in the cuticle the decayed parts are thrown off at the
free surface ; in the vascular tissiies, on the other hand, the old or effete
matter must be first reduced to a liquid state, then find its way into the
blood-vessels, or lymphatics, along with the residual part of the nutritive
plasma, and be by them carried off. But, in certain cases, the mode of
removal of the old matter is not clear ; as, for example, in the crystalline
lens, which is destitute of vessels, and grows by deposition of blastema and
formation of cells at its surface ; here we should infer that the oldest parts
were nearest the centre, and if we suppose them to be changed in nutrition,
it is puzzling to account for their removal.
From what has been said, it is clear that the vessels are not proved to perform any
other part, in the series of changes above described, beyond that of conveying matter
to and from the scene of nutrition ; and that this, though a necessary condition, is
not the essential part of the process. The several acts of assuming and assimilating
new matter, of conferring on it organic structure and form, and of disorganising
again that which is to be removed, which are so many manifestations of the metabolic
and plastic properties already spoken of, are performed beyond the blood-vessels. It
is plain, also, that a tissue, though devoid of vessels, and the elements of a vascular
tissue, though placed at an appreciable distance from the vessels, may still be organised
and living structures, and within the dominion of the nutritive process. How far the
sphere of nutrition may, in certain cases, be limited, is a question that still needs
further investigation ; in the cuticle, for example, and its appendages, the nails and
hairs, which are placed on the surface of the body, we must suppose that the old and
dry part, which is about to be thrown off or worn away, has passed out of the limits
of nutritive influence ; but to what distance beyond the vascular surface of the skin
the province of nutrition extends, has not been determined.
Regeneration. When part of a texture has been lost or removed, the
THE BLOOD.
loss may be repaired by regeneration of a new portion of tissue of ths same
kind ; but the extent to which this restoration is possible is very different
in different textures. Thus, in muscle, a breach of continuity may be
repaired by a new growth of connective tissue ; but the lost muscular sub-
stance is not restored. Regeneration occurs in nerve ; in bone it takes
place readily and extensively, and still more so in fibrous, areolar, and
epithelial tissue. The special circumstances of the regenerative process in
each tissue will be considered hereafter ; but we may here state generally,
that, as far as is known, the reproduction of a texture is effected in the
same manner as its original formation.
In experimental inquiries respecting regeneration, we must bear in mind,
that the extent to which reparation is possible, as well as the readiness with
which it occurs, is much greater in many of the lower animals than in man.
In newts, and some other cold-blooded vertebrata, indeed (not to mention
still more wonderful instances of regeneration in animals lower in the scale),
an entire organ, a limb, for example, is readily restored, complete in all its
parts, and perfect in all its tissues.
In concluding what it has been deemed advisable in the foregoing pages to state
respecting the development of the textures, we may remark that, besides what
is due to its intrinsic importance, the study of this subject derives great interest
from the aid it promises to afford in its application to pathological inquiries. Re-
searches which have been made within the last few years, and which are still zealously
carried on, tend to show that the structures which constitute morbid growths are
formed by a process analogous to that by which the natural or sound tissues are
developed : some of these morbid productions, indeed, are in no way to be distin-
guished from areolar, fibrous, cartilaginous, and other natural structures, and have,
doubtless, a similar mode of origin ; others, again, as far as yet appears, are peculiar
in structure and composition, but still their production is with much probability to be
referred to the same general process. The prosecution of this subject, however, does
not fall within the scope of the present work.
THE BLOOD.
PHYSICAL AND ORGANIC CONSTITUTION.
The most striking external character of the blood is its well-known colour,
which is florid red in the arteries, but of a dark purple or modena tint in the
veins. It is a somewhat clammy and consistent liquid, a little heavier than
water, its specific gravity being 1052 to 1057; it has a saltish taste, a
slight alkaline reaction, and a peculiar faint odour.
To the naked eye the blood appears homogeneous ; but, when examined
with the microscope, either while within the minute vessels, or when spread
out into a thin layer upon a piece of glass, it is seen to consist of a trans-
parent colourless fluid, named the " lymph of the blood," " liquor sanguinis,"
or " plasma," and minute solid particles or corpuscles immersed in it.
These corpuscles are of two kinds, the red and the colourless : the former
are by far the most abundant and have been long known as "the red
particles," or "globules," of the blood; the "colourless," "white," or
" pale corpuscles," on tha other hand, being fewer in number and less
conspicuous, were later in being generally recognised. When blood is
drawn from the vessels, the liquor sanguinis separates into two parts ;
into fibrin, which becomes solid, and a pale yellowish liquid named serum.
The fibrin in solidifying involves the corpuscles and forms a red consistent
THE BLOOD.
mass, named the clot or crassamentum of the blood, from which the serum
gradually separates. The relation between the above-mentioned constituents
of the blood in the liquid and the coagulated states may be represented by
the subjoined scheme :
Liquid
blood
Corpuscles .
Liquor sanguinis
Fibrin
Scrum
Clot
Coagulated blood.
Red Corpuscles. These are not spherical, as the name " globules," by
which they have been so generally designated, would seem to imply, but
flattened or disk-shaped. Those of the human blood
Fig. XV,
(fig. xv., lf 2 ) have a nearly circular outline, like a
Fig. XV. RED COR-
PUSCLES OF HUMAN
BLOOD ; MAGNIFIED
ABOUT 500 DIAMETERS
(Wagner).
1, shows depression
on the surface ; 2, a
corpuscle seen edgeways ;
3, red corpuscles altered
by exposure.
piece of coin, and most of them also present a shallow
cup-like depression or dimple on both surfaces ; their
usual figure is, therefore, that of biconcave disks.
Their magnitude differs somewhat even in the same
drop of blood, and it has been variously assigned by
authors ; but the prevalent size may be stated at
from 3 3*0 ^ th to -g-gVo^ ^ an ^ nca * n diameter, and
about one-fourth of that in thickness.
In mammiferous animals generally, the red cor-
puscles are shaped as in man, except in the camel
tribe, in which they have an elliptical outline. In
birds, reptiles, and most fishes, they are oval disks
with a central elevation on both surfaces (fig. xvi.,
from the frog), the height and extent of which, as
well as the proportionate length and breadth of the
oval, vary in different instances, so that in some osseous fishes the elliptical
form is almost shortened into a circle. The blood-corpuscles of invertebrata,
although they (except in some of
Fig. XVI. the red-blooded annelid es) want the
red colour, are also, for the most
part, flattened or disk-shaped ;
being in some cases circular, in
others oblong, as in the larvas of
aquatic insects. Sometimes they ap-
pear granulated on the surface like
a raspberry, but this is probably due
to some alteration occurring in them.
The size of the corpuscles differs
greatly in different kinds of ani-
mals ; it is greater in birds than in
mammalia, and largest of all in the
naked amphibia. They are for the
most part smaller in quadrupeds
than in man ; in the elephant,
however, they are larger, being
gYQ^th of an inch, which is the
largest size yet observed in the blood-corpuscles of any mammiferous
Fig. XVI. BLOOD CORPUSCLES OF THE FROG;
MAGNIFIED ABOUT 500 DIAMETERS.
1, shows their broad surface ; 2, one seen
edgeways ; 3, shows the effect of weak
acetic acid ; the nucleus has become distinct ;
4, a colourless or lymph corpuscle (from
Wagner).
CORPUSCLES.
animal: the goat was long supposed to have the smallest, viz., about
of an inch ; but Mr. Gulliver has found that they are much smaller in the
Meminna and Napu musk-deer, in which animals they are less than ju^^th
of an inch. In birds they do not vary in size so much ; from Mr. Gulliver's
very elaborate tables of measurement it appears that they range in length from
about yy'o-oth to Y^Vo^ ^ an i ucu ne states that their breadth is usually
a little more than half the length, and their thickness about a third of the
breadth or rather more. He found a remarkable exception in the cor-
puscles of the snowy owl, which measure ^--^ n th of an inch in length ; and
are only about a third of this in breadth. In scaly reptiles they are from
j-^^th to y^ 1 ,} o^k f an i nca * n length ; in the naked amphibia they are
much larger : thus, in the frog they are -jo'Vo-th f an i ncn l n g an( i TToo^k
broad ; in the salamander they are larger still ; but the largest yet known in
any animal are those of the proteus, which are -j^th of an inch in length,
and T ^ T th in breadth ; the siren, which is so much allied to the proteus in
other respects, agrees with it also in the very large size of its blood-
corpuscles ; they measure -j-^th of an inch in length, and -yg-oth in breadth.
In the skate and shark tribe the corpuscles resemble those of the frog, in
other fishes they are smaller.
From what has been stated, it will be seen that the size of the blood-cor-
puscles in animals generally is not proportionate to the size of the body ; at
the same time Mr. Gulliver remarks, that " if we compare the measure-
ments made from a great number of different species of the same order, it
will be found that there is a closer connection between the size of the
animal and that of its blood-corpuscles than has been generally supposed ; "
and he has pointed out at least one example of a very natural group of
quadrupeds, the ruminants, in which there is a gradation of the size of the
corpuscles in relation to that of the body.
C. Schmidt, on account of the varying size which the corpuscles
present, in dependence upon the density of the liquor sanguinis, has sub-
jected them to repeated measurements when dried, in a very thin layer upon
slips of glass. It has been thus found that from 95 to 98 per cent, present
the same magnitude.
Structure. The large corpuscles of the frog and salamander, when drawn
from the vessels and placed under the microscope, appear to consist of a thin,
transparent, vesicular envelope, enclosing a solid oval nucleus in the centre,
with a quantity of softer red-coloured matter disposed round the nucleus and
filling up the space between it and the envelope. When exposed to the
action of weak acetic acid, (fig. xvi., 3 ) the colouring matter is speedily
extracted, and the nucleus becomes distinct, whilst the envelope is rendered
so faint as to be scarcely visible ; but its outline may be still brought
into view by adding solution of iodine, which gives it colour and opacity.
Pure water extracts the colour and distends the corpuscle by imbibition,
altering its shape from oval to round, and making the nucleus more
conspicuous. Often in these circumstances the nucleus is displaced from its
central position, and it may even be extruded altogether, as if by bursting
of the corpuscle, which then appears flattened and colourless, and in this con-
dition is generally supposed to represent only the ruptured and empty
envelope ; but even with the help of iodine, no rent can be perceived in it.
For this and also for other reasons some think that what remains behind
after escape of the nucleus is really the soft and now colourless substance of
the corpuscle, and that it has no distinct envelope. On the opposite view it
is suggested that the absence of apparent laceration in the envelope is owing
xxx THE BLOOD.
to plasticity of its substance ; and the case has been compared to the section
of a soap-bubble into two or more without destruction or collapse. Dr. W.
Roberts,* who makes this comparison, has brought forward some curious
observations on the effects of solutions of magenta and of tannin on the
corpuscles of man and various animals, which seem to him to speak for the
presence of an envelope. It must, I think, be admitted that the question is
open to debate, but it could not be settled by even a much more extended
discussion than could suitably be introduced here.
The distension by water is caused by the thinner exterior fluid passing by
endosmosis into the thicker matter of the corpuscle ; and precisely the opposite
effect may be produced by immersing the corpuscles in a fluid of a sufficiently
high degree of concentration, so as to cause the predominant current to pass
from within outwards. Accordingly, on using a strong solution of salt or of
sugar, the corpuscles will shrink and become thinner ; and, no doubt, the
variations in plumpness which they often naturally present, are owing to
differences in the degree of concentration of the surrounding liquid. The
nucleus (fig. xvi., 3 ) is rather more than a third of the length of the cor-
puscle ; it appears, especially after being exposed to the action of vinegar,
to be composed of tolerably large granules, and, when FO treated at least, it
is quite free from colour. But it must be remembered that it is only after
exposure of the corpuscles that a nucleus becomes apparent ; nothing of the
kind is observable when they are seen within the vessels, so that some think
the nuclei are formed by a sort of precipitation or consolidation in the
substance of the corpuscles when they are withdrawn from the animal. The
envelope is supposed to be an exceedingly fine, homogeneous, and pellucid
membrane. The coloured content of the corpuscle is a pale reddish matter ;
not liquid, but obviously of a soft and yielding nature, for the corpuscles
alter their shape on the slightest pressure, as is beautifully seen while they
move within the vessels ; they are also elastic, for they readily recover their
original form again. It must be remarked that the blood-corpuscles when
viewed singly appear very faintly coloured, and it is only when collected in
considerable quantity that they produce a strong deep red.
A structure similar to that shown in the large blood-disks of amphibia,
may be demonstrated in many other instances, and by analogy has been
inferred to exist in all, man not excepted. But although the blood-cor-
puscles of man and mammalia are nucleated in the early stages of their
formation, it is now satisfactorily established that in their perfect or final
condition they are destitute of nuclei. As to an envelope, some observers,
who admit its presence in the red corpuscles of oviparous vertebrata, doubt
its existence in mammalian blood-disks. From long continued and
careful observation, Mr. Gulliver concludes that the mammalian red cor-
puscle consists of two parts ; viz., 1, a tegumentary membranous frame of
colourless, homogeneous, structureless substance, containing, 2, a semi-
fluid, viscid, coloured matter. The effect of water is to extract the easily
* Proceedings of the Royal Society, vol. xii. p. 481. Hensen, who also holds to the
belief of an envelope, thinks that the red corpuscle of the frog contains protoplasm in a
layer next the envelope, and also round the nucleus, and elsewhere a coloured intra-
cellular fluid. His observations show that the contents may be separated into two
substances, but they are by no means conclusive as to the alleged natural distribution of
these substances within the corpuscle. (Zeitschr. fur wiss. Zoologie, 1861, p. 263.)
For some interesting observations by Dr. W. Addison, F.R.S., on the curious effects
produced on red blood-corpuscles by immersion in sherry-wine, see Proceedings of the
Royal Society, Dec. 8, 1859.
CORPUSCLES. xxx i
soluble coloured substance from the tegumentary frame, which is insoluble,
and remains behind, shrunk to about two-thirds of its original diameter.
To me the human blood- corpuscles, when deprived of their coloured part by
means of distilled water, and subsequently treated with solution of iodine,
appear under the microscope like somewhat thick shrunken sloughs.
The human blood-corpuscles, as well as those of the lower animals, often
present deviations from the natural shape, which are most probably due to
causes acting after the blood has been drawn from the vessels, but in some
instances depend upon abnormal conditions previously existing in the blood.
Thus, it is not unusual for many of them to appear indented or jagged at
the margin, when exposed under the microscope, (fig. xv. , 3 ) and the number
of corpuscles so altered often appears to increase during the time of observa-
tion. This is, perhaps, the most common change ; but they may become
distorted in various other ways, and corrugated on the surface ; not unfre-
quently one of their concave sides is bent out, and they acquire a cup-like
figure. It is even a question with some observers, whether the biconcave
figure which the corpuscles generally present may not be due to a distension
of the circumferential part of an originally flat disk. Mr. Gulliver made
the curious discovery that the corpuscles of the Mexican deer and some
allied species present very singular forms, doubtless in consequence of ex-
posure ; the figures they assume are various, but most of them become
lengthened and pointed at the ends, and then often slightly bent, not unlike
caraway-seeds.
The red disks, when blood is drawn from the vessels, sink in the plasma ;
they have a singular tendency to run together, and to cohere by their
broad surfaces, so as to form by their aggregation cylindrical columns, like
piles or rouleaus of money, and the rolls or piles themselves join together
into an irregular network (fig. xvn.). In a few moments after this has taken
place, a heaving or slowly oscillating motion is
observable in the mass, and the rolls may then
become broken up, and the corpuscles more or
less completely disjoined (Jones). Generally
the corpuscles separate on a slight impulse, and
they may then unite again. The phenomenon
is probably of a physical kind : it will take
place in blood that has stood for some hours
after it has been drawn, and also when the
globules are immersed in serum in place of
liquor sanguiuis.
By processes, which need not here be detailed,
Yierordt and Welcker have estimated the number
of red corpuscles in a cubic millimetre of human Fig- XVII. RED CORPUSCLES
blood. The former assigns it at upwards of COLLECTED INTO ROLLS (after
5.000,000 ; the latter at^5,000,000 in the male, and Henle).
4^500,000 in the female?
Pale or colourless Corpuscles (fig xvm.). These are comparatively few in
number, of a rounded and slightly flattened figure, rather larger in man and
mammalia than the red disks, and varying much less than the latter in
size and aspect in different animals. In man (during health) the proportion
of the white corpuscles to the red is about 2 or 3 to 1000. This proportion
is diminished by fasting and increased after a meal, especially of albuminous
food. Their number compared with the red corpuscles is said to be greater
xxxii THE BLOOD.
in venous than arterial blood ; and it is much greater in the blood of the
splenic and hepatic veins than in venous blood generally. They are destitute
of colour, finely granulated on the surface, and specifically lighter than the
red corpuscles. The large corpuscles are less distinctly granular than the
small. Water has little effect on them ; acetic acid brings speedily into
view a nucleus, which frequently presents a reddish tint (Virchow and
Kb'lliker), consisting sometimes of one, but more commonly of two, three,
or four, large clear granules (fig. xvm. , 2 3 ). The
Fig. XVIII. number of apparent nuclei is said by Mr. Wharton
/rim Jones to depend upon the strength of the acetic acid
^ employed ; if the acid be much diluted, only one is
* * seen ; if strong acid be used, the nucleus breaks up
V) (jo) into three or four nuclear-looking particles. Under
the action of the acid the circumferential part of the
Fig. XVIII PALE cor P usc l e becomes clear of granules and pellucid, and
CORPUSCLES' OF Hu- swells up by imbibition with a regular and well-
MAN BLOOD ; MAGNI- defined outline, which has teen taken for the indi-
FIED ABOUT 500 DiA- cat i on O f a f ne envelope, but conclusive evidence
on this point is wanting. The clear substance is
1 natural aspect; 2 evei)tua i ly dissolved, the nucleus remaining,
and 3, acted on by weak m . *
acetic acid, which brings The P ale corpuscles frequently undergo curious
into view the single or changes of shape, sending out processes into which
composite nucleus. the granules enter, and retracting them again ; in
short, exhibiting phenomena which have been aptly
compared to the movements of an amoeba.
Albuminous granules and molecules of a fatty nature occur in the blood
in varying numbers ; sometimes very scantily, or not at all, but the latter
sometimes in vast numbers so as to give the serum a turbid, milky
appearance. These are probably derived directly from the chyle (its
"molecular base"), and they are especially seen in the blood of herbivora,
in sucking animals, and in pregnant women.
' Occasional elements. Besides the foregoing, the blood occasionally presents
the following constituents : (1) bodies like cells, enclosing blood-corpuscles,
noticed by Ecker and Kolliker in the blood of the spleen and hepatic
vessels, and elsewhere. (2) Pigmentous granule-cells. (3) Pale, fine-granular,
roundish aggregations, in the splenic blood. (4) Peculiar bodies, three or
four times larger than the pale corpuscles, but in other respects resembling
them. (5) Caudate, pale, or pigmentous cells. (6) Fibrinous coagula.
Liquor Sanguinis, or Plasma. This is the pale clear fluid in which the
corpuscles are naturally immersed. Its great character is its strong ten-
dency to coagulate when the blood is withdrawn from the circulating current,
and on this account it is difficult to procure it free from the corpuscles.
Nevertheless, by filtering the slowly coagulable blood of the frog, as was
first practised by Miiller, the large corpuscles are retained by the filter,
while the liquor sanguinis comes through in perfectly clear and colourless
drops, which, while yet clinging to the funnel, or after they have fallen
into the recipient, separate into a pellucid glassy film of fibrin, and an
equally transparent diffluent serum. When human blood is drawn in in-
flammatory diseases, as well as in some other conditions of the system, the
red particles separate from the liquor sanguinis before coagulation, and
leave the upper part of the liquid clear. In this case, however, the plasma
is still mixed with the pale corpuscles, which, being light, accumulate at the
top. On coagulation taking place in these circumstances, the upper part of
CHEMICAL COMPOSITION. xxxiii
the clot remains free from redness, and forms the well-known " buffy coat"
so apt to appear in inflammatory blood. Now, in such cases, a portion of
the clear liquor may be taken up with a spoon, and allowed to separate by
coagulation into its fibrin and serum, so as to demonstrate its nature.
Professor Andrew Buchanan has pointed out another method of separating
the liquor sanguiuis from the red corpuscles, which I have repeatedly tried
with success ; it consists in mixing fresh-drawn blood with six or eight times
its bulk of serum, allowing the red particles to subside, and then decanting
the supernatant fluid, and filtering it through blotting-paper ; the admixture
of serum delays coagulation, and a great part of the liquor sanguinis, of
course diluted, and usually more or less coloured, passes through the filter,
and subsequently coagulates.
Coagulated plasma, whether obtained from buffy blood, or exuded on
inflamed surfaces, presents, under the microscope, a multitude of fine fila-
ments confusedly interwoven, as in a piece of felt ; but these are more or
less obscured by the intermixture of corpuscles and fine granules, the former
having all the characters of the pale corpuscles of the blood. The filaments
are no doubt formed by the fibrin, as it solidifies in the coagulation of the
liquor sanguinis.
Blood may be freed from fibrin by stirring it with a bundle of twigs,
which entangle the fibrin as it concretes.
CHEMICAL COMPOSITION OF THE BLOOD.
The blood is slightly alkaline in reaction. Carbonic acid, oxygen, and
nitrogen gases may be extracted from it, by exhaustion (Magnus), by
heating after dilution with water (L. Meyer), or by both these means com-
bined (Setschenow). Carbonic acid is yielded in largest proportion, oxygen
next, and nitrogen least. The nitrogen appears to be simply retained by
absorption, the other two partly by absorption and partly by weak chemical
combination. The combined oxygen is probably in great part held by some
component of the red corpuscles ; the carbonic acid, which is obtained in
larger measure from serum, seems to be combined partly with carbonate of
soda in a bicarbonate, and partly with phosphate of soda, from both of
which combinations it can be set loose by heat and reduction of pressure.
Arterial blood yields more oxygen and less carbonic acid than venous
blood.
On being evaporated, 1000 parts of blood yield, on an average, about
790 of water and 210 of solid residue. This residue has nearly the same
ultimate composition as flesh. A comparative examination of dried ox-
blood and dried flesh (beef), by Playfair and Boeckmann, gave the following
mean result :
Flesh. Blood.
Carbon 51-86 51 "96
Hydrogen 7'58 7'25
Nitrogen 15'03 15'07
Oxygen 21'30 21'30
Ashes " . 4-23 4'42
Red Corpuscles. The specific gravity of the red corpuscles, in a moist
c
xxxiv THE BLOOD.
state, is calculated at I 1 088. They consist, as already stated, of an
insoluble, colourless tegumentary substance (envelope) and an included red
matter which is soluble and separable by water. The former doubtless
belongs to the group of albuminoids or protein-bodies, and some have
regarded it as a species of fibrin, but in truth it cannot be specifically
characterised. In numerical statements of blood-analysis it is reckoned
along with the globulin. The soluble coloured ingredient, for which it is
convenient to retain the old name of m*or, is separable into two sub-
stances, one named globulin, of itself colourless, and very nearly allied to
albumen in its nature ; the other a colouring principle, named h<jematin or
lic&matosin, which imparts redness to the first ; and hence the cruor is often
also designated as hwmato-globulin. These may be separated by the following
process.
Blood deprived of fibrin by stirring is mixed with at least four times its bulk of
saturated solution of sulphate of soda, and thrown upon a filter; a few of the corpuscles
pass through with the liquid, but the greater part remain on the filter in form of a
moist red mass. This is boiled with alcohol slightly acidulated with sulphuric acid ;
the hsematin is thereby dissolved, while the colourless globulin remains behind.
Carbonate of ammonia is then added to the acid solution of haematin while it is yet
hot, to remove sulphuric acid, and, after being cleared by filtration from sulphate of
ammonia, and a little globulin which is precipitated, the liquor is evaporated to a
twelfth of its bulk ; it then deposits the haematin in form of a dark brown or almost
black powder, from which a minute proportion of fat may be extracted by means of
ether.
Hcematin thus obtained appears to be altered by the process of separa-
tion, for it is no longer soluble in water. It is insoluble also in alcohol
and ether ; but it readily dissolves in any of these liquids after being
mixed with potash, soda, or ammonia, forming deep red solutions. It
likewise dissolves in alcohol to which an acid has been added, but its acid
combinations are insoluble in water. When burned, it yields nearly ten
per cent, of peroxide of iron, representing nearly seven per cent, of iron.
The quantity of iron is estimated by Schmidt as 1 to 230 parts of red cor-
puscles. According to Mulder, hsematin is composed of carbon 6 5 '8 4,
hydrogen 5 '37, nitrogen 10*40, oxygen 11'75, and iron 6*64 ; or C 44 , H 22 ,
N 8 , 6 , Fe.
That haematin is an altered product is further shown by an observation of Hoppe,
confirmed by Stokes, both of whom have found that the solution of cruor (obtained by
diffusing the red clot in water) is speedily decomposed by acids, and that the coloured
product of decomposition, which has all the characters of haematin, agrees with
haematin in its effects on the prismatic spectrum, but differs in this respect from the
natural or unaltered colouring matter of the cruor, which Mr. Stokes distinguishes by
the name of cruorin*
There has been much question as to the condition in which the iron exists in
haematin, and especially whether it be in the state of oxide and in special combination
with some part of the constituent oxygen, or associated in an elementary form with
the organic matter, as sulphur is in albumen. The latter view seems to be the more
probable, for the whole of the iron may be removed from haematin, without abstracting
oxygen or disturbing the relative proportions of the other elements. When thus
* For an account of the examination of the colouring matter of the blood by the prism,
and of the differences in its absorptive effect on light, according to its oxidated or
deoxidated condition, the reader is referred to an important paper by Professor Gr. G.
Stokes, in the Proceedings of the Royal Society for June 16, 1864, vol. xiii. p. 355.
CHEMICAL COMPOSITION. xxxv
deprived of iron, the haematin retains its colour, and has suffered no appreciable
change in character. It would seem therefore that iron, although a constant ingre-
dient in the red corpuscle, is not an essential constituent of haematin, and it is, at
any rate, clear that the red colour of the blood is not caused by iron.
Globulin. When the haematin has been extracted from the blood-
corpuscles by the foregoing method, the globulin and envelopes remain in
combination or mixture with sulphuric acid. Globulin is a protein com-
pound, agreeing very nearly with albumen and casein in elementary com-
position, so far as this has been ascertained, but most resembling the latter
substance in its general characters. Globulin is nearly insoluble in pure
water, but readily dissolves on a very slight addition of either an alkali or
an acid. Weak acids throw it down from its solution in alkali, but when
added in slight excess re-dissolve it. In like manner it is precipitated by
alkalies from its solutions in acids and re-dissolved by excess. From neither
of these solutions is it thrown down by heat. It is dissolved by neutral salts,
and from this solution heat throws it down in an insoluble precipitate.
From its slightly alkaline solution in water it is thrown down by a stream
of carbonic acid, and may be re-dissolved by passing air or oxygen through
the liquid. Its precipitate is distinguished from that of other albuminoids
by beiug always in form of fine granules or molecules. But the most im-
portant and distinctive character of globulin is its fibrino-plastic property,
to be afterwards further referred to, by which it co-operates with another
protein -substance in producing solid fibrin ; this property is destroyed by
exposure of the solution to a boiling heat.
Globulin forms the greater part of the crystalline lens, and it is no doubt present
in the pale blood-corpuscles ; it exists also in the chyle and lymph, the cornea, the
aqueous humour, and various other tissues and fluids, if its presence is to be inferred
from the manifestation of the fibrino-plastic property. The globulin of the red cor-
puscles is crystallisable, as will be presently explained.
The cruor, or the soluble matter of the red corpuscles, which consists of
the globulin and colouring principle (the cruorin of Stokes) together, forms
in water a solution (maintained probably by soda and salts) which in its
effects with re-agents agrees with solution of globulin. Berzelius reckons
the relative proportions of globulin and hseinatin as 94 '5 of the former, and
5- 5 of the latter. Schmidt makes them 87 '59, and 12-41 respectively. The
corpuscles also contain a solid phosphuretted fat in small quantity, which
may be stated at rather more than 2 parts in the 100 of dried corpuscles.
100 parts of dried cruor yield by calcination about 1'3 of brown alkaline
ashes, which consist of carbonate of alkali with traces of phosphate 0'3,
phosphate of lime 0*1, lime 0'2, subphosphate of iron O'l, peroxide of iron
0*5, carbonic acid and loss O'l.
Blood-crystals. In the blood of man and various animals, when drawn
from the vessels and set aside for a time, red crystals occasionally appear,
consisting of globulin tinted by the colouring matter : and their formation
may be promoted by adding water to defibriuated blood so as to set free the
cruor from the corpuscles, and exposing the watered blood first to a stream
of oxygen and then to carbonic acid. Or a drop of blood, defibrinated or
not, is to be mixed with a little water on a slip of glass, exposed for a little
to the air, then breathed upon, and finally covered with thin glass and
placed in a bright light, which seems to favour the crystallisation. The
THE BLOOD.
crystals are said readily to appear in both cases ; but I must confess that
the second method has generally failed in my hands with human or bullock's
blood. The addition of alcohol, ether, and especially chloroform, greatly
promotes the operation.
From human blood, and that of most mammals, the crystals are pris-
matic in form (fig. xix., 1 ), but tetrahedral in the guineapig, rat, and
mouse ( 2 ), hexagonal plates in the squirrel ( 3 ), and rhombohedrons in the
hamster ( 4 ).*
Fig. XIX. The crystallising matter is perhaps modi-
fied in its properties under these different
forms ; at least, it has been found that all
are not equally soluble in water. The red
colouring principle (haematin) is not essen-
tial to the crystals, for Lehmann has, by
i-ecrystallisation, obtained them free from
colour, and apparently unchanged in other
respects; neither does the undissolved
envelope or tegumentary frame of the
corpuscle take any share in the crystallisa-
tion. The crystallising matter, therefore,
must be the colourless protein-substance of
the cruor, namely, globulin. It has been
proposed to call this substance "blood-
crystalline," on account of its property of
crystallising, which does not belong to the
globulin of the crystalline lens, so far as is
>i r \^ y e ^ known. The change of name, however,
^^^fi is confusing, and appears inexpedient, espe-
"^^J v^ cially as we know that all forms of globulin
\/ agree in the much more characteristic pro-
perty of being fibrino plastic.
The haematin itself, or some chemical
modification of it, can also, it is supposed.be
crystallised; and the rhombic prisms and
acicular crystals (hcemin crystals), obtained
by Teichmann by treating blood with concentrated acetic acid, are considered to be
of this nature. Crystals, moreover, of a substance (also occurring amorphously) which
has been named "haematoidin," and is probably derived from modified heematin, are
often found in old coagula and effusions of blood within the body. These occur in
form of rhombic plates or prisms, of a yellow or red colour; they are insoluble in
water, alcohol, ether, and acetic acid, and contain no iron.
Fig. XIX. BLOOD-CKYSTALS MAGNIFIED.
1, from human blood ; 2, from the
guineapig ; 3, squirrel ; 4, hamster.
Proportion of red Corpuscles. The red corpuscles form by far the largest
part of the organic matter in the blood : their proportion may be ascer-
tained by filtering defibrinated blood mixed with solution of Glauber's salt,
as already mentioned ; or by weighing the dried clot, and making allow-
ance for the fibrin it contains. The latter method, however, will serve
only to give a rough estimate, as the very uncertain amount of serum
remaining in the clot and affecting its weight cannot be determined.
Prevost and Dumas made too large a deduction for the solid matter sup-
posed to belong to the retained serum, and this reduced the estimate of
* A late writer, Bojanowski, represents them as rectangular tables in man and
hexagonal plates in the mouse. Zeitsch. f. Wissensch. Zool. 1862.
CHEMICAL COMPOSITION. xxxvii
the dried corpuscles too much, viz. to 129 parts per 1000 of blood. Le-
canu also gives it at from 120 to 130 : Becquerel and Rodier at from 131
to 152. Schmidt, from three modes of calculation, which it is needless here
to explain, arrived at the conclusion that the proportion of moist red cor-
puscles in 1000 parts of blood is from 480 to 520 ; but there are reasons
for regarding this as too high an estimate. He considers that in the moist
state they consist of 31 per cent, of solid matter and 69 per cent, of water :
on this understanding, of course, much of the water estimated by the loss in
drying blood must be assigned to the corpuscles.*
Different observers agree that, as a general rule, the proportion of red particles is
greater in the blood of the male sex than in that of the female. Lecanu gives the
following mean result, derived from numerous analyses, exhibiting the proportion of
dry crassamentum and water in the blood of the two sexes. No deduction is made
for the fibrin ; but, considering its small relative quantity, any possible variation in
it cannot materially affect the general conclusion.
Male. Female.
Crassamentum, from . 115-8 to 148 . . 68'3 to 129'9
Water . . . . 778 to 805 . . 790 to 853
Becquerel and Rodier state the crassamentum in the female at from 113 to 137.
Lecanu found the following differences in the crassamentum according to
temperament :
Male. Female.
Sanguine temperament . . . 136'4 . . . 126-1
Lymphatic temperament . . 116'6 . . . 117'3
As regards age, Denis found the proportion of crassamentum greatest between the
ages of 30 and 40. Sudden loss of blood rapidly diminishes it. In two women who
had suffered from uterine haemorrhage, the crassamentum amounted to only 70 parts
in 1000. The same effect may be observed to follow ordinary venesection. In a
person bled three times in one day, Lecanu found in the first drawn blood 139, and
in the last only 76 parts of crassamentum in the 1000. This effect may be produced
very suddenly after a bleeding. Prevost and Dumas bled a cat from the jugular
vein, and found 116 parts of crassamentum in 1000, but in blood drawn five minutes
afterwards, it Avas reduced to 93. The sudden loss of blood probably causes a rapid
absorption of serous and watery fluid into the vessels, and thus diminishes the relative
amount of the red particles. It is found that the blood of warm-blooded animals is
richer in crassamentum than that of the cold-blooded ; and, among the former, the
proportion is highest in the class of birds.
Liquor Sanguinis. The fluid part of the blood, as already described,
separates spontaneously into fibrin and serum. The fibrin may be obtained
by stirring the blood as soon as possible after it is drawn, or by washing
the crassamentum with water, to free it from cruor. Procured in either
of these ways, the fibrin contains pale corpuscles and a small portion of fat.
From dried fibrin of healthy human blood, Nasse obtained near 5 per cent,
of fat, and still more from the fibrin of buffy blood. The proportion of
fibrin in the blood does not exceed 2^ parts in 1000 ; indeed, according to
the greater number of observers, it is not more than 2J-. As a general rule,
the quantity is somewhat greater in arterial than in venous blood, and it is
increased in certain states of the body, especially in inflammatory diseases
and in pregnancy. Nasse thinks that the whole fibrin cannot be separated
* For an account of Schmidt's method, see Lehmann's Physiological Chemistry
(Cavendish Society's Translation), vol. ii.
xxxviii THE BLOOD.
from the blood by the processes employed, for he believes that a portion
remains suspended in the liquid in form of minute microscopic scales or
films.
Denis pointed out, that fibrin obtained from the coagulum of venous blood, if quite
recent, and not previously much exposed to the air, is capable of being slowly dis-
solved in a slightly-heated solution of nitre. Scherer and Nasse have confirmed this
statement, and the latter finds that fibrin got by stirring may also be dissolved in the
same way, provided it is quite fresh. On the other hand, nitre does not dissolve
fibrin of arterial blood, nor fibrin that has been some time exposed to the air, from
whatever source it may be derived; nor, according to Scherer, the fibrin of the
buffy coat.
Origin of Fibrin. It is now ascertained that the fibrin is not present, as
such, in a liquid form, in the plasma, but is produced at the moment of
consolidation by the co-operation or combination of two previously distinct
substances. About twenty years ago, Professor Andrew Buchanan* disco-
vered that the fluid of hydrocele, which might in an unmixed state be
kept for an indefinite time without coagulating, very speedily congealed
and separated into clot and serum when mixed with a little blood. Ordi-
nary blood-serum, blood-clot, especially washed clot, and buffy coat, even
after being dried and long kept, when added in small proportion to the
hydrocele- fluid, produced the same effect. From these facts Dr. Buchanan
concluded that fibrin exists as a liquid both in hydrocele-fluid and in the
liquor sanguinis, that liquid fibrin does not coagulate spontaneously, but
requires for that end the influence of some " suitable re-agents," that such
a re-agent is naturally present in the blood, and brings about the solidifica-
tion of its fibrin in the natural process of coagulation, and that it is absent
from the hydrocele fluid, but when supplied by the addition of blood,
causes the fluid fibrin to solidify. On further reasoning on the facts he
had observed, Dr. Buchanan was led to believe that " coagulant power "
was mainly seated in the pale corpuscles, which abound in the washed
clot and the buffy coat, and are present in the serum ; and that their
efficacy depended on their organisation as elementary cells. In harmony
with this latter view, he found on trial that the organised tissues, such as
muscle, skin, and spinal marrow, possessed the same power, though in a
less degree than the pale corpuscles, in which, as primary cells, the meta-
bolic power is more energetic.
The remarkable phenomenon described by Dr. Buchanan did not obtain
the consideration it deserved, and the coagulation of hydrocele-fluid under
the conditions stated, was commonly ascribed to some catalytic action of
the substance added, which induced liquid fibrin present in the fluid to
solidify. In 1861, however, Dr. A. Schmidt, of Dorpat, apparently un-
aware of Dr. Buchanan's observations, fell upon facts of the same kind, and
pursuing the investigation by an elaborate series of experiments not only
with hydrocele-fluid, but with pericardial, peritoneal, and other serous fluids
and effusions, which give a like result, has satisfactorily shown that fibrin
has no existence in a liquid state, but that when it appears as a coagulum
in a fluid, it is actually produced then and there by the union of two con-
stituents present in solution, and forthwith shed out as a solid matter.
One of these constituents, which contributes in largest measure to the pro-
* Proceedings of the Glasgow Philosophical Society, Feb. 19, 1845.
CHEMICAL COMPOSITION. xxxix
duct, he names fibrinogenous substance, the other fibrinoplastic substance.
In the coagulation of hydrocele-fluid, the former, or fibrinogen, is already
there, while the fibrinoplastin is supplied from the blood. It is not that
the latter converts albumen into fibrin, for, after a certain amount of fibrin
has been coagulated from the serous fluid, no further addition will generate
more, although abundance of albumen remains; and again, a given quantity
of fibrinoplastin will not coagulate with equal rapidity and intensity any
amount of fluid containing fibrinogen. In short, the fibrinoplastic sub-
stance seems not to operate as a ferment or by catalysis, but by combining
with the other necessary ingredient. Now Schmidt has shown that the
fibrinoplastic matter presents all the chemical characters of globulin, and is
in fact nothing else than that substance. Accordingly, he finds, as already
stated, that blood-crystals are highly fibrinoplastic. This globulin is not
restricted to the red corpuscles ; it exudes from them into the plasma in the
coagulation of the blood, and a residual portion remains in the serum when
the process is over ; globulin doubtless exists also in the pale corpuscles.
Nor is it confined to the blood. From chyle and lymph, from the aqueous
humour of the eye and watery extract of the cornea, from the vitreous
humour and crystalline lens, from connective tissue, and from saliva and
synovia, a substance may be obtained having the same re-actions and the
same fibrinoplastic power. Fibrinogen may be thrown down from hydrocele-
fluid by a mixture of alcohol and ether ; it very closely resembles globulin
in its chemical relations, only it is less soluble in acids and alkalies, and less
energetic in all its re-actions. Of course, it exists in blood-plasma, and in
the process of coagulation of the blood combines with globulin, transuded
from the corpuscles, to form the fibrin of the clot.*
Serum. This is a thin and usually transparent liquid, of a pale yellowish
hue ; it is, however, sometimes turbid, or milky, and this turbidity may
depend upon different conditions, but most commonly on excess of fatty
molecules. The specific gravity of serum ranges from 1025 to 1 030, but is
most commonly between 1027 and 1028 (Nasse), and is more constant than
that of the blood. The solid contents of the serum are not more than 8 or
9 in 100 parts ; the proportion of water being, for males 90 '88, and for
females 91 '71. It is always more or less alkaline. When heated, it
coagulates, in consequence of the large quantity of albumen it contains ;
and after separation of the albumen, a thin saline liquid remains, some-
times named " serosity." The following ingredients are found in the
serum.
Albumen. This principle is considered to be combined with soda as an
albuminate ; its quantity may be determined by precipitating it in the
solid form by means of heat or alcohol, washing with distilled water,
drying, and weighing the mass. Its proportion is about 80 in 1000 of
serum, or nearly 40 in 1000 of blood.
Globulin. When serum is diluted with about ten times its bulk of
distilled water, and subjected to a stream of carbonic acid, the liquid
becomes turbid, and globulin is precipitated. It may also be obtained from
the diluted serum by the cautious addition of acetic acid, but the least
* Schmidt, Alex., in Reichert & Du Bois Raymond's Archiv. fur Anat. n. Physiol.,
1861 and 1862. For a lucid account of the progress and present state of this question,
founded on a confirmatory repetition of Buchanan's and of Schmidt's fundamental experi-
ments, see an article on "the Coagulation of the Blood," [by Dr. Michael Foster,] in the
Natural History Review for 1864, p. 157.
xl THE BLOOD.
excess of acid will re-dissolve the precipitate. This globulin is probably
the casein of the serum described by various authorities.
Fatly Compounds. It has been already stated that the red corpuscles and
the fibrin yield a certain quantity of fat ; but a portion of the fat of the
blood remains in the serum, partly dissolved, and partly diffused in. the
liquid. It may be separated by gently agitating the serum with about a
third of its bulk of ether, or by evaporating the serum and digesting the dry
residue in ether, or in boiling alcohol. The turbid milky aspect which
serum often exhibits, is in most cases due to a redundance of fat, and may
accordingly be removed by agitation with ether.
The fatty matters of the blood are of various kinds, viz., cholesferin, serolin, and
the ordinary saponifiable fats of the body (margarates and oleates) ; also, according to
Berzelius and Lecanu, a phosphuretted fat, similar to that found in the brain. Berze-
lius, indeed, is disposed to think that the blood contains every variety of fat that is
found in other parts of the body. Lecanu could not obtain the phosphuretted fat
from either the serum or the fibrin, and Berzelius therefore supposes that it is asso-
ciated with the red corpuscles ; he also states that the fat extracted from the fibrin is
different from ordinary fat. The usual quantity of fat of all kinds in 1000 parts of
blood is stated by Lecanu to be 515, by Simon 2 - 3, and by Nasse 2*0.
Extractive Matters. When the serum has been freed from albuminous
matter by coagulation, and from fat by ether, and is evaporated to dryness,
a yellowish or brown mass remains, consisting of organic matters mixed with
salts ; the former belonging principally to the ill-defined class of substances
denominated "extractive matters." These have now been more carefully
sifted, and have yielded several definite and recognisable bodies, generated
in the natural process of decomposition of the tissues, or residual matters of
nutrition formed in the blood itself, and on their way to be excreted by the
kidneys. Several of the substances to be next mentioned belong to this
class, and as they are obviously excrementitial and transitory ingredients,
they are not allowed to gather in any notable quantity in the healthy state
of the economy.
Creatin and Creatinin. Products of the natural " wear " of the muscles,
or derived from fleshy food. These compounds, which are found in muscular
substance and in the urine, together with hypoxanthin (also named sarkiri),
obtainable from the same sources, have been stated to exist in excessively
small quantities in the blood.
Urea. This substance, which accumulates in the blood of animals after
extirpation of the kidneys or ligature of the renal arteries, as well as in
certain diseases, has been found in very minute quantity in the healthy
blood of the ox and of the calf, by Marchand and Simon, and in that of
roan, by Lehmann, Garrod, and others. It is, however, in such excessively
small quantity, that its estimation is attended with great difficulty.
Uric Acid has been shown to exist in healthy blood by Dr. Garrod, and
in that of persons suffering from gout it is in such considerable quantity as
to be readily detected. In health its proportion is extremely small.
Hippuric Acid is found in the blood of herbivora, and according to some
observers in that of man. There is, however, much doubt upon this point.
Leucin and Tyrosin, which exist in almost all secretions and excretions,
probably are present in minute quantity in the blood ; but as yet they have
only been detected in it in disease of the liver.
Sugar has been found in the blood of dogs, oxen, and cats, also in that
CHEMICAL COMPOSITION. xli
of diseased and healthy persons. The quantity is very small. The form of
sugar is that known as glucose or grape sugar.
Colouring Principles. A yellow or greenish-yellow colouring principle,
supposed to be the same as that of the bile, has been found by various
chemists in the blood of persons affected with jaundice, and, according to
Lecanu and Denis, a certain amount of it may be detected even in healthy
blood. The colouring matter which gives a pale yellowish tint to ordinary
serum does not, however, exhibit the reactions of bile-pigments.
Odoriferous Matters. Denis describes three. 1. One combined with fat,
smelling like garlick. 2. One supposed to depend on a volatile oil, with an
odour said to be of peculiar character in each species of animal, and to be
heightened by adding sulphuric acid to the blood. 3. One of a variable
character, derived from the food. Schmidt found that the blood of only
three animals yielded an odour distinctive of the species.
Salts. 1. Having soda and potash as bases, combined with lactic,
carbonic, phosphoric, sulphuric, and fatty acids. Also chlorides of sodium
and potassium, the former in large proportion. Schmidt has pointed out
that the potash-salts exist almost exclusively in the blood- corpuscles and the
soda salts principally in the serum. In the corpuscles there are principally
chloride of potassium and phosphate of potass : in the serum, chloride of
sodium, and phosphate of soda. The following table (giving the mean of
eight experiments) exhibits the relative quantities of potassium and sodium,
and of phosphoric acid and chlorine, in the blood-corpuscles and plasma.
100 parts of Inorganic Matters.
flood- Ci
K.
wpusdes.
Na.
Plat
K.
ma.
Na.
Blood- Cc
P0 5 .
irpusdes.
Cl.
Pla.
P0 5 .
^ma.
Cl.
40-89
971
5-19
3774
17-64
21-00
6-08
40-68
The Table shows that the chlorides are, relatively to the phosphates, in much
larger quantity in the plasma than in the blood-corpuscles ; and that the phosphates
are, relatively to the chlorides, in much larger proportion in the blood-corpuscles than
in the plasma.
2. Lactate of ammonia. 3. Salts with earthy bases, viz. , lime and magnesia
with phosphoric, carbonic, and sulphuric acids.
The earthy salts are for the most part associated with the albumen, but partly with
the crassamentum. As they are obtained by calcination, it has been suspected that
the phosphoric and sulphuric acids may be in part formed by oxidation of the phos-
phorus and sulphur of the organic compounds. Nasse found in 1000 parts of blood
4 to 7 of alkaline, and 0'53 of earthy salts.
Mean Composition. The following statement of the mean composition of
human venous blood is from Lecanu. (Etudes chimiques sur le sang
huniain, Paris, 1837.)
xlii
THE BLOOD.
Free oxygen, nitrogen, and carbonic acid)
Extractive matters
Fatty matters, viz.
Phosphuretted fat
Cholesterin
Serolin
Oleic and margaric acids (free)
Ditto combined with soda
Volatile odoriferous oily acid
(combined with a base.)
Salts, viz.
Chloride of sodium
potassium
ammonium
Carbonate of soda
,, lime
magnesia
Phosphate of soda
lime
,, magnesia
Lactate of soda
Yellow colouring matter
Albumen ......
Water
Fibrin
Hsematin . . . 2 27 ) n
Albumen (globulin) 125-63 j Cor P uscles
10-98
67-80
790-37
2-95
Serum
86915
Crassamentum ISO' 85
1000-
Lecanu's statement refers all the water of the blood to the serum, and thus
exaggerates the quantity of albumen. The following statement (from
Lehmann) may be taken as a more correct account of the distribution
of the several constituents ; but the proportion assigned of albumen is
probably somewhat too low.
Water
Hsematin
Globulin and Envelopes
Fat
Extractive matters
Saline .,
Fibrin
Albumen .
In 1000 parts of Blood.
Corpuscles. Plasma.
. 344 451-45
. . 8-375
141-110
1-155
1-300
4-060
500-
0-860
1-970
4-275
2-025
39-420
500-
Total.
795-450
8-375
141-110
2-015
3-270
8-335
2-025
39-420
1000-
Difference "between Arterial and Venous Blood. By arterial blood is meant that
which is contained in the aorta and its branches (systemic arteries), the pulmonary
veins and left cavities of the heart ; the venous blood is that of the veins generally,
the pulmonary arteries, and right cavities of the heart. Their differences, apart from
their functional effects in the living body, come under the heads of colour and com-
position.
1. Colour. Arterial blood, as already stated, is scarlet, venous blood dark, or
purple. Venous blood assumes the scarlet colour on exposure to air, i. e., to oxygen.
This change is greatly promoted by the saline matter of the serum, and may be
accelerated by adding salts or sugar to blood, especially by carbonate of potash, or of
soda, and by nitre. Salts added to dark blood, without exposure to oxygen or air,
cause it to assume a red colour, but not equal in brightness to that of arterial blood. On
DIFFERENCES IX DIFFERENT VESSELS. xliii
the other hand, the addition of a little water darkens the blood. According to Pro-
fessor Stokes, the corpuscles in the former case "lose water by exosmosis, and become
thereby highly refractive, in consequence of which a more copious reflexion takes
place at the common surface of the corpuscles and surrounding fluid. In the latter
case they gain water by endosmosis, which makes their refractive power more nearly
equal to that of the fluid in which they are contained, and the reflexion is conse-
quently diminished."* But the presence of serum or of saline matter is not indis-
pensable to the brightening, for although the clot when washed free from serum
scarcely if at all reddens on exposure to oxygen, yet it is found that the red matter
when squeezed out of the clot and dissolved in water, still becomes brighter and
clearer on exposure to oxygen, whilst the colour is darkened (and the solution
becomes turbid from deposition of globulin), on being shaken with carbonic acid. As
in this case the colouring matter is extracted from the corpuscles and is reddened by
oxygen without the presence of salts, it is plain that the difference of colour of arterial
and venous blood essentially depends, not on a difference in the figure or density
of the corpuscles, but on an alteration produced in their colouring substance by
oxidation and deoxidation, which alters its absorptive effect on the light.
2. Composition. The arterial blood, so far as is known, is uniform in nature
throughout ; but in passing through the capillary vessels into the veins, whilst it
generally acquires the common characters of venous blood, it undergoes special
changes in its passage through particular organs, so that the blood of all veins is not
alike in quality. Thus the blood of the hepatic veins differs from that of the portal
vein, and both are in various respects different from what might be regarded as the
common venous blood, which is conveyed by the veins of the limbs, and of the
muscular and cutaneous parts of the body generally. Moreover, Bernard has shown
that the blood of veins returning from secreting glands differs according to the state
of functional activity of the organs. Whilst their function is in abeyance the blood
in their veins is dark, as usual, but when secretion is active, the blood, which then
also flows much more freely and abundantly, comes through from the arteries to the
veins with very little, if any, reduction of its arterial brightness ; it also retains
nearly the whole of its separable oxygen.
Compared with blood from a cutaneous vein, arterial blood is found to contain a
very little more water (about five parts in 1000) and to have a somewhat lower specific
gravity. The arterial plasma yields more fibrin and coagulates more quickly; the
serum is said by Lehmann to contain less albumen and less fat, but more extractive
and a little more saline matter. According to the same authority, the corpuscles also
contain less fat, but relatively more hsematin and salts. Arterial blood yields more
oxygen gas, and less of both free and combined carbonic acid.
Blood of the portal vein, compared with that of the jugular vein, is stated by
Lehmann to contain more water in proportion to solid matter, less fibrin and
albumen, more fat, extractive matter and salts. Its corpuscles are said to be richer
in haematin.
In the blood of the splenic vein, as compared with that of the corresponding artery,
according to the observations of Funke, the red corpuscles are smaller, more
spheroidal in form, and more resistant to the destructive effects of water ; and when
they run together it is in rounded heaps, not in regular piles. Their cruor has a
marked tendency to form crystals. The pale corpuscles are vastly more numerous
than in the arterial blood, and some of them have a yellowish tint (as if in transition
to red disks). Granule-cells occur occasionally and sparingly, twice as large as the
pale corpuscles, but otherwise resembling them. The plasma is distinguished by its
poverty in fibrin.
The blood of the hepatic veins shows, according to Lehmann's statement, the
following differences from that of the portal vein. It is richer in both red and pale
corpuscles, possibly from loss of water. The red corpuscles present the same pecu-
liarities of size, form, resistance to water, and mode of aggregation, as in the splenic
venous blood. They contain less fat and salts than in portal blood, less haematin, at
least less iron, but somewhat more extractive matter; the proportion of pale cor-
puscles to the red is increased. The plasma is more concentrated, but is deficient in
* Proc. Royal Soc., vol. xiii. p. 362.
xliv THE BLOOD.
fibrin (or spontaneously coagulating matter), and docs not form a true clot. The
serum contains less albumen and fat, and much less saline, but more extractive
matter. The hepatic venous blood, moreover, yields sugar, derived from glycogen
formed in the liver.
The blood of the renal veins is said by Bernard and Brown-Sequard not to coagu-
late in the normal state of the kidney and its function, from which they infer that it
contains little or no fibrin ; but it may be that there is something present which
prevents the two constituents of the fibrin from reacting on each other.
COAGULATION OP THE BLOOD.
In explaining the constitution of the plasma, we have been obliged so far
to anticipate the account of the coagulation of the blood. The following are
the phenomena which usher in and which accompany this remarkable change.
Immediately after it is drawn, the blood emits a sort of exhalation, the
" halitus " having a faint smell ; in about three or four minutes a film
appears on the surface, quickly spreading from the circumference to the
middle ; a minute or two later the part of the blood in contact with the
inside of the vessel becomes solid, then speedily the whole mass ; so that,
in about eight or nine minutes after being drawn, the blood is completely
gelatinised. At about fifteen or twenty minutes, or it may be much later,
the jelly-like mass begins to shrink away from the sides of the vessel, and
the serum to exude from it. The clot continues to contract, and the serum
to escape for several hours, the rapidity and degree of the contraction
varying exceedingly in different cases ; and, if the serum be poured off,
more will usually continue to drain slowly from the clot for two or three
days.
The nature of the change which takes place in the coagulation of the
blood has been already spoken of ; it is essentially owing to the coagulation
of the liquor sanguinis, the fibrin being generated in that liquid by the con-
currence of its two constituents in the way already explained, and separating
in form of a solid mass, which involves the corpuscles but allows the serum
to escape from it in greater or less quantity. But although the solidification
of the fibrin and formation of a red clot would undoubtedly take place inde-
pendently of any mechanical co-operation on the part of the corpuscles, still
it must not be forgotten that the red disks are not altogether indifferent
while coagulation goes on ; for they run together into rolls, as already
described, and the circumstance of their doing so with greater or with less
promptitude materially affects the result of the coagulating process. Thus
there seems good reason to believe that, as H. Nasse has pointed out, one
of the causes and in inflammatory blood probably the chief cause of the
production of the buffy coat, is an exaltation of the natural tendency of the
red disks to run together, whereby being more promptly and more closely
aggregated into compact masses, they more speedily subside through the
liquid plasma, leaving the upper part of it colourless by the time coagulation
sets in ; and Mr. Jones has drawn attention to another influential circum-
stance depending likewise on the corpuscles, in inflammatory blood, namely,
the more rapid and close contraction of the network, or sponge work as he
terms it, into which the little rolls of corpuscles unite, and the consequent
expulsion of the great part of the liquor sanguinis from its meshes before the
fibrin solidifies, in which case the mass of aggregated corpuscles naturally
tends to the lower part of the vessel, whilst the expressed plasma, being
lighter, accumulates at the top. Of course it is not meant to deny that
more tardy coagulation of the plasma would produce the same result as more
COAGULATION. x l v
speedy aggregation of the corpuscles ; it is well known, indeed, that blood
may be made to show a buffy coat by delaying its coagulation, but buffed
inflammatory blood is not necessarily slow in coagulating.
Circumstances affecting Coagulation. Various causes accelerate, retard, or
entirely prevent the coagulation of the blood ; of these it will here suffice to
indicate the more important and best ascertained.
1. Temperature. Cold delays, and at or below 40 degrees Fahr. wholly
suspends, coagulation ; but even frozen blood, when thawed and heated
again, will coagulate. Moderate elevation of temperature above that of the
body promotes coagulation.
2. Coagulation is accelerated by contact of the blood with foreign matter,
such as the sides of the basin or other vessel into which it is drawn. On
the other hand, the maintenance of its fluidity is favoured by retention
within its vessels or natural receptacles where it is in contact with the
natural tissues of the body ; but when the coats of the vessels or other
tissues, with which the blood is contiguous, lose their vitality and are
altered in their properties, they become as foreign bodies, and coagulation is
promoted. The usual exposure of drawn blood to the air promotes coagula-
tion, but according to Lister, by no means so powerfully as has been hereto-
fore generally understood. The effect of other gases is the same. Coagulation
speedily takes place when blood is subjected to the air-pump, and has
therefore been said to occur readily in vacuo, but Lister finds that this is
owing to the agitation caused by the bubbling of the blood from the escape
of liberated gas, whereby more and more of it is successively brought into
contact with the sides of the vessel.
3. Arrest of the blood's motion within the body favours coagulation,
probably by arresting those perpetual changes of material, both destructive
and renovative, to which it is naturally subject in its rapid course through the
system. The coagulation of the stagnant blood after death is also largely to be
ascribed to the alteration then ensuing in the coats of the containing vessels.
Lister found that, after death, blood remains longer fluid in the small veins
than in the heart and great vessels ; and even in these the coagulation is
usually slow. Agitation of exposed blood accelerates coagulation by in-
creasing its exposure to foreign contact.
4. Water, in a proportion not exceeding twice the bulk of the blood,
hastens coagulation ; a larger quantity retards it. Blood also coagulates
more speedily when the serum is of low specific gravity, indicative of much
water in proportion to the saline ingredients.
5. Almost every substance that has been tried, except the caustic alkalies,
when added to the blood in minute proportion, hastens its coagulation ;
although many of the same substances, when mixed with it in somewhat
larger quantity, have an opposite effect. The salts of the alkalies and
earths, added in the proportion of two or three per cent, and upwards, retard,
and, when above a certain quantity, suspend or prevent coagulation ; but,
though the process be thus suspended, it speedily ensues on diluting the
mixture with water. Caustic potash and soda permanently destroy the
coagulability of the blood. Acids delay or prevent coagulation. Opium,
extract of belladonna, and many other medicinal agents from the vegetable
kingdom, are said to have a similar effect when mixed with the blood ; but
the statements of experimenters by no means entirely agree respecting
them.
6. Certain states of the system. Faintness occasioned by loss of blood
favours coagulation ; states of excitement are said to have, though not
xlvi THE BLOOD.
invariably, the opposite effect. Impeded aeration of the blood in disease,
or in suflbcative modes of death, makes it slow to coagulate; probably from
retention of carbonic acid. In cold-blooded animals, with slow circulation
and low respiration, the blood coagulates less rapidly than iu the warm-
blooded ; and, among the latter, the tendency of the blood to coagulate is
strongest in birds, which have the greatest amount of respiration, and
highest temperature.
7. Coagulation commences earlier, and is sooner completed, in arterial
than in venous blood. Dr. Nasse finds that women's blood begins to
coagulate nearly two minutes sooner than that of the male sex.
In general, when blood coagulates quickly, the clot is more bulky and
less firm, and the serum is less effectually expressed from it ; so that causes
which affect the rapidity of coagulation will also occasion differences in the
proportion of the moist clot to the exuded serum.
There is no sufficient evidence of evolution of heat or of disengagement of
carbonic acid from blood during its coagulation, which some have supposed
to occur.
Theory of Coagulation. Although it is certain that the coagulation of the blood
consists in solidification of fibrin, and although it seems tolerably well established
that this is the result of the combination of two primarily separate animal principles,
it is by no means clearly understood how such combination and solidification do not
naturally take place within the living body, and how the several conditions already
mentioned as influencing the process operate in promoting or opposing coagulation.
According to the explanation proposed a few years ago by Dr. B. W. Richardson,*
the blood is kept liquid within the vessels by ammonia, which maintains the fibrin in
solution (or, as it may be now expressed, hinders the union of fibrinogen and
globulin), and drawn blood coagulates in consequence of the loss of ammonia which
escapes from it on exposure. Drawn blood placed in an atmosphere of ammonia
remains fluid; and, according to Dr. Richardson, the natural presence of ammonia in
blood may be demonstrated, as well as its extrication from blood on exposure to air
or in a vacuum. The more extensive and thorough the exposure, the more speedy is
the escape of ammonia, and the quicker is the coagulation. Heat hastens coagulation
by hastening the extrication of ammonia, whilst, by retaining it, cold delays or
suspends the change. Moreover Dr. R. found that air which had become charged
with the volatile element by passing through one portion of blood delayed the coagu-
lation of another portion through which it was sent.
Nothing could at first sight appear more natural and consistent than this explana-
tion ; but of the facts on which it mainly rests, some have since been disputed, and
others differently interpreted. Thus after a most elaborate research, a late inquirer
(Thiry) has been unable to find evidence of free ammonia in fresh blood. Again,
Lister finds that blood may be poured from one piece of a vein into another, in a small
stream through the air several times, so as to give ample opportunity for the escape of
ammonia, and yet remain fluid for hours after. Lastly, the different effects of heat
and cold may be ascribed to their influence in promoting or hindering the mutual
reaction of the two constituents of the fibrin.
According to another view, which is fundamentally the same as that entertained
by John Hunter and some other British physiologists, and which has recently been
advocated by Professor Briicke of Vienna, f the blood has a natural tendency to
coagulate ; or, if we may use the language suggested by later researches, the globulin
and fibrinogen naturally tend to combine ; within the body this tendency is held in
check by some inhibitory or restraining influence exercised by the coats of the
vessels and the living tissues in contact with the blood ; but when blood is withdrawn
from its natural receptacles, or if these lose their vitality, its intrinsic disposition to
* The Cause of the Coagulation of the Blood. 1857.
f British and Foreign Medico-Chirurgical Review, vol. xix. 1857.
THE LYMPH AND CHYLE. xlvii
coagulate being no longer opposed, is allowed to prevail. At the same time it is not
inconsistent with this theory to admit the positive efficacy of contact with foreign or
dead matter in promoting coagulation. Mr. Lister,* on the other hand, considers
that the blood has no spontaneous tendency to coagulate, either within or without
the vessels, but that the coagulation is brought about in drawn blood by contact with
foreign matter. Accepting the conclusion of Schmidt, that globulin and fibrinogen
are necessary to the evolution of fibrin, he thinks that, if these bodies unite in
ordinary chemical combination, the action of foreign matter may determine their
union, as spongy platinum promotes the combination of oxygen and hydrogen. He
considers that the living vessels do not exert any action to prevent coagulation, but
that their peculiarity, as distinguished from an ordinary solid, consists in the remark-
able circumstance that their lining membrane, in a state of health, is wholly negative
in its relation to coagulation, and does not cause that molecular disturbance, so to
speak, which is produced in the blood by all ordinary matter. When the vessels lose
their peculiar property by death, or become seriously altered by disease or injury,
their contact with the blood induces coagulation like that of an extraneous body.
Finally, it may be observed, that in any attempted explanation of the coagulation of
the blood, it is well to bear in mind that there is a purely physical or chemical
phenomenon, which, as suggested by Mr. Graham, has a certain analogy to it, namely,
the change from the liquid to the insoluble state so easily induced in colloidal matter
by slight external causes.
THE LYMPH AUD CHYLE.
A transparent and nearly colourless fluid, named " lymph," is conveyed
into the blood by a set of vessels distinct from those of the sanguiferous
system. These vessels, which are named " lymphatics," from the nature of
their contents, and " absorbents," on account of their reputed office, take
their rise in nearly all parts of the body, and, after a longer or shorter
course, discharge themselves into the great veins of the neck ; the greater
number of them previously joining into a main trunk, named the thoracic
duct, a long narrow vessel which rises up in front of the vertebrae, and
opens into the veins on the left side of the neck, at the angle of union of
the subclavian and internal jugular ; whilst the remaining lymphatics termi-
nate in the corresponding veins of the right side. The absorbents of the
small intestine carry an opaque white liquid, named " chyle," which they
absorb from the food as it passes along the alimentary canal ; and, on
account of the milky aspect of their contents, they have been called the
"lacteal vessels." But in thus distinguishing these vessels by name, it
must be remembered, that they differ from the rest of the absorbents only
in the nature of the matters which they convey ; and that this difference
holds good only while digestion is going on ; for at other times the lacteals
contain a clear fluid, not to be distinguished from lymph. The lacteals
enter the commencement of the thoracic duct, and the chyle, mingling with
the lymph derived from the lower part of the body, is conveyed along that
canal into the blood.
Glands. Both lacteals and lymphatics, in proceeding to their destination,
pass into and out of certain small, solid, and vascular bodies, named lym-
phatic glands, which have a special structure and internal arrangement, as
will be afterwards described ; so that both the chyle and lymph are sent
through these glands before being mixed with the blood.
This much having been explained to render intelligible what follows, we
* On the Coagulation of the Blood ; the Croonian Lecture for 1863, Proceedings of the
Royal Society, vol. xii. p. 580.
xlviii THE LYMPH AND CHYLE.
may now consider the lymph and the chyle, which, as will be seen, are
intimately related to the blood.
LYMPH.
The lymph may be procured free from admixture of chyle, and in quan-
tity sufficient for examination, from the larger lymphatic vessels of the
horse or ass. It may also be obtained by opening the thoracic duct of an
animal that has fasted for some time before being killed. It is a thin
fluid, transparent and colourless, or occasionally of a pale yellow hue ;
its taste is saline, its smell faint and scarcely perceptible, and its reaction
alkaline. Sometimes the lymph has a decided red tint, of greater or less
depth, which becomes brighter on exposure to the air. This redness is due
to the presence of coloured corpuscles, like those of the blood : and it has
been sometimes supposed, that such corpuscles exist naturally in the lymph,
in greater or less quantity ; but they are more probably introduced into the
lymphatic vessels accidentally. It can, in fact, be shown that when an
incision is made into a part, the blood very readily enters the lymphatics
which are laid open, and passes along into larger trunks ; and in this way
blood is conveyed into the thoracic duct, or any other large vessel, exposed
as usual by incision immediately after the animal is killed. Indeed, mere
rough handling of some organs, such as the liver and spleen, will rupture
the fine vessels and cause the contents of the issuing lymphatics speedily to
become red from admixture of blood.
The lymph, when examined with the microscope, is seen to consist of a
clear liquid, with corpuscles floating in it. These "lymph-corpuscles," or
lymph- globules, agree entirely in their characters with the pale corpuscles
of the blood, which have been already described (page xxxi. ). It is alleged
that some of the lymph corpuscles have a yellowish tint. Occasionally,
smaller particles are found in the lymph ; also, but more rarely, a few oil
globules of various sizes, as well as red blood-corpuscles, the presence of
which has just been referred to.
The liquid part (lymph -plasma) bears a strong resemblance in its physical
and chemical constitution to the plasma of the blood ; and accordingly,
lymph fresh-drawn from the vessels coagulates after a few minutes' expo-
sure, and separates after a time into clot and serum. This change is owing
to the combination of the constituents of the fibrin contained in the lymph-
plasma, and in this process most of the corpuscles are entangled in the
coagulum. The serum, like the corresponding part of the blood, consists
of water, albumen, extractive matters, fatty matters in very sparing quan-
tity, and salts. Sugar exists in small quantity in the lymph, and urea, in
the proportion of from O'Ol to 0'02 per cent. ; leucin has also been found,
at least in the lymphatic glands.
Human lymph has been obtained fresh from the living body in several
instances, from lymphatic vessels, opened by wounds or other causes. It
has been found to agree in all material points with the lymph of quad-
rupeds.
CHYLE.
The chyle of man and mammiferous animals is an opaque, white fluid,
like milk, with a faint odour and saltish taste, slightly alkaline or alto-
gether neutral in its reaction. It has often a decided red tint, especially
when taken from the thoracic duct. This colour, which is heightened by
THE LYMPH AND CHYLE. xlix
exposure to air, is doubtless generally due to the presence of blood-cor-
puscles, and may be explained in the same way as the occasional red colour
of lymph.
Like blood and lymph, both of which fluids it greatly resembles in con-
stitution, the chyle consists of a liquid holding small particles in suspension.
These particles are, 1. Chyle-corpuscles, or chyle-globules, precisely like the
lymph-globules and pale blood-corpuscles already described. 2. Molecules,
of almost immeasurably minute but remarkably uniform size. These abound
in the fluid, and form an opaque white molecular matter diffused in it, which
Mr. Gulliver has named the molecular base of the chyle. The addition of
ether instantly dissolves this matter, and renders the chyle nearly, but not
quite, transparent ; whence it may be inferred that the molecules are minute
particles of fatty matter, and no doubt the chief cause of the opacity and
whiteness of the chyle. According to the late Prof. H. Miiller, they are
each coated with a fine film of albuminoid matter. They exhibit the usual
tremulous movement common to the molecules of many other substances.
3. Oil-globules ; these are of various sizes, but much larger than the mole-
cules above described, and are often found in the chyle in considerable
numbers. 4. Minute spherules (Gulliver), from -Q-^^Q-^ to -3^-3 of an inch
in diameter ; probably of an albuminous nature, and distinguished from the
fatty molecules by their varying magnitude and their insolubility in ether.
The Free nuclei described in the chyle by Kolliker he now considers to be
derived from corpuscles accidentally ruptured in the examination.
The plasma, or liquid part of the chyle, contains fibrin, so that chyle
coagulates on being drawn from the vessels, and nearly all the chyle-cor-
puscles, with part of the molecular base, are involved in the clot. The
serum which remains resembles in composition the serum of lymph ; the
most notable difference between them being the larger proportion of fatty
matter contained in the chyle-serum.
The following analyses of lymph and chyle exhibit the proportions of the different
ingredients ; but it must be explained that the amount of the corpuscles cannot be
separately given, the greater part of them being included in the clot and reckoned
as fibrin. No. 1 is the mean of two analyses, by Gubler and Quevenne, of human
lymph taken during life from the lymphatics of the thigh ; No. 2, the mean of three
analyses by Gmelin of lymph from the thoracic duct of horses after privation of food ;
No. 3, by Dr. 0. Rees, of chyle from the lacteals of an ass, after passing the
mesenteric glands.
L IT. III.
Water . . . 937'32 939-70 902'37
Fibrin . . . 0'595 10-60 370
Albumen . . . 42'775 38'83 35-16
Fat . . . . 6-51 a little 36'01
Extractive matter . 5 - 05
Salts . 7-75' 10 ' 87 22 ' 7(i
1000- 1000- 1000-
The extractive matters of the chyle and lymph probably vary with the nature of the
food : they generally contain sugar and urea in appreciable quantities.
The chyle, when taken from the lacteal vessels before it has reached the glands,
is generally found to coagulate less firmly than in a more advanced stage of its
progress. In like manner the lymph, before passing the lymphatic glands, occasion-
ally exhibits the same weak coagulation ; but Mr. Lane justly remarks, that the
lymph does not differ in coagulability in the different stages of its progress so
d
1 FORMATION OF BLOOD-CORPUSCLES.
decidedly and so generally as has been sometimes alleged; and this observation
accords with the statement of Mr. Hewson on the same point.
Dr. Rees has examined the fluid contained in the thoracic duct of the human
subject. It was obtained from the body of a criminal an hour and a half after
execution, and, from the small quantity of food taken for some hours before death,
it must have consisted principally of lymph. It had a milky hue with a slight tinge
of buff; part of it coagulated feebly on cooling: its specific gravity was 1024. Its
analysis, compared with that of chyle from the ass, showed less water, more albumen,
less aqueous extractive, and a great deal less fat.
FORMATION OF THE CORPUSCLES OF THE LYMPH AND CHYLE.
The lymph-plasma appears to consist fundamentally of blood-plasma, which,
having exuded from the capillary blood-vessels and yielded nutritive material to the
tissues, is, with more or less admixture of waste products, returned by the lymphatics.
As to the origin of the lymph and chyle corpuscles, it may, in the first place, be
observed that the greatly increased proportion of these bodies in the vessels which
issue from the lymphatic glands, and the vast store of corpuscles having the same
characters contained in the interior recesses of these glands, are unmistakeable indi-
cations that the glands are at least a principal seat of their production. They are,
most probably, produced by division of parent corpuscles or cells contained in the
glands, and in some measure also by further division of corpuscles thus produced,
after they have made their way into the lymphatic vessels. The corpuscles found
sparingly both in chyle and lymph before passing the mesenteric glands may be in
part formed in the agminated and solitary follicular glands of the intestine which,
though differing" much in form, yet in essential structure have much in common
with the lymphatic glands and may come partly also from the irregular deposits of
pale corpuscles, which have recently been recognised in the intestinal mucous mem-
brane. Lymph-corpuscles are supposed also to be produced in the spleen, and in the
thymus and thyroid glands; but corpuscles, although few in number, and not
invariably present, have been found in the lymph of various regions of the body
before it has reached the glands, and they are present in the lymph of cold-blooded
vertebrata, whose lymphatic vessels, although forming a well developed system, do
not pass through glands. It, therefore, seems necessary to admit some further source
of the corpuscles ; but what this may be is very much a matter of conjecture. It
has been suggested that lymph-corpuscles are produced by multiplication of cells in
the epithelium which lines the lymphatic vessels, in the same way as mucus-cor-
puscles are supposed to be formed from the epithelium of mucous membranes.
FORMATION OF THE BLOOD-CORPUSCLES.
In the embryo ofbatracliians. In the early embryo of the frog and newt (in which,
perhaps, the steps of the process are best ascertained), at the time when the circu-
lation of the blood commences, the corpuscles in that fluid appear as rounded cells,
filled with granular matter, and of larger average size than the future blood-corpuscles.
The bodies in question, although spoken of as cells and presenting a regularly defined
outline, have no separable envelope. They contain, concealed in the midst of the
granular mass, a pellucid globular nucleus, which usually presents one or two small
clear specks, situated eccentrically. The granular contents consist partly of fine
molecules, exhibiting the usual molecular movements ; and partly of little angular
plates, or tablets, of a solid substance, probably of a fatty nature. After a few days,
most of the cells have assumed an oval figure, and are somewhat reduced in size ;
and the granular matter is greatly diminished in quantity, so that the nucleus is
conspicuous. Now, also, the blood-corpuscles, previously colourless, have acquired a
yellowish or faintly red colour. In a further stage, the already oval cell is flattened,
the granules entirely disappear, the colour is more decided, and, in short, the blood-
corpuscle acquires its permanent characters. From this description it will be seen
that the blood-cells which first appear agree in nature with the embryonic cells
(described at page xvi), and ^they are, in all probability, produced by the process of
segmentation, which is known to take place in the frog's ovum. The different parts
of the embryo in its early condition, the heart, for example, are for a time, entirely
composed of cells of the same kind, and all have probably a common origin.
FORMATION OF BLOOD-CORPUSCLES. li
In the bird. In the egg of the bird, the first appearance of blood-corpuscles, as
well as of blood-vessels, is seen in the blastoderma, or germinal membrane, a structure
formed by the extension of the cicatricula in the early stages of incubation. The
commencing embryo, with its simple tubular heart, is seen in the middle of this
circular membrane, and blood-vessels, containing blood-corpuscles, appear over a
great part of its area. These first vessels, therefore, though connected with the
heart, and intended to convey nutriment to the embryo, are formed in an exterior
structure ; but, in a somewhat later stage, blood-vessels and corpuscles are developed
in various textures and organs within the body. The formation of blood-corpuscles
in the vascular area of the blastoderma has been sedulously investigated by various
inquirers ; and from their concurrent statements, we learn that these corpuscles, at a
certain stage of their progress, are rounded bodies, larger than the blood-disks of the
adult. They contain a granular nucleus, and are quite devoid of colour. These
spheroidal colourless corpuscles in their further advancement become flattened, and
assume an oval figure. While undergoing these changes of form, they acquire a
red colour, which is at first faint and yellowish, but gradually deepens.
As to the earlier part of the process the production of the above-mentioned round
cells, whose subsequent conversion into coloured oval disks has just been described
it has been held that the cells which form the substance of the blastoderma and
embryo partly pass directly into blood-corpuscles, and partly generate the latter by
fissiparous multiplication.
In man and mammalia. In the embryo of man and mammalia the primitive
blood-corpuscles are round, nucleated, colourless bodies, as in the cases above de-
scribed. Their substance, originally granular, speedily clears up and acquires colour,
and thus they appear as nucleated red corpuscles, of spheroidal shape, and of much
larger size than the future red disks. They are embryonic cells, most probably
loosened from each other and set free in the excavation of the originally solid vessels
in the blastoderma and embryo-body ; and, both in their primitive state and after
acquiring colour, they increase in number by fissiparous multiplication, as represented
in fig. XL, p. xvii. These large nucleated red and colourless corpuscles, continuing
to increase in number, constitute the earliest and, for a time, the only corpuscles in
the embryo-vessels. But their multiplication is soon arrested, and a new epoch in
blood-formation begins with the development of the liver. The blood which returns
to the embryo charged with fresh material of nutrition from the maternal system,
has then to pass, at first entirely, afterwards in great part, through the vessels of the
liver ; and it would seem that henceforth colourless nucleated corpuscles are produced
in that organ and poured abundantly into the general mass of blood by the hepatic
veins. It is probable that the liver continues its haemapoietic or blood-forming
function throughout foetal life ; but, in the meanwhile, the spleen and lymphatic
system have also begun to produce pale corpuscles, and in after periods supersede the
liver in that ofiice. These corpuscles, either immediately or after fissiparous multi-
plication, acquire colour like the first those from the liver and spleen probably in
great part before they leave these organs and are converted into nucleated red
corpuscles. The nucleated red corpuscles thus produced are gradually converted
into, or at least succeeded by, smaller disk-shaped red corpuscles without nuclei,
having all the characters of the blood-disks of the adult. This transition or sub-
stitution begins early, and proceeds gradually, until at length, long before the end of
intrauterine life, the nucleated red corpuscles have altogether vanished.
Throughout life the mass of blood is subject to continual change ; a portion of it is
constantly expended, and its place taken by a fresh supply. It is certain that the
corpuscles are not exempted from this general change, but it is not known in what
manner they are consumed, nor has the process been fully traced by which new ones
are continually formed to supply the place of the old. With regard to the latter
question, it may be stated, that the explanation which has hitherto found most favour
with physiologists is, that the corpuscles of the chyle and lymph, passing into the
sanguiferous system, become the pale corpuscles of the blood ; and that these last are
converted into red disks. Pale corpuscles are also generated in the spleen, and, after
part of them have changed into red disks, pass directly into the blood, independently
of those derived from the chyle and lymph. As to the manner in which the pale
corpuscles are transformed into the red, there is considerable difference of opinion.
Hi EPITHELIUM.
According to one view (adopted by Paget, Kolliker, Funke, and others), the pale
corpuscles gradually become flattened, acquire coloured contents, lose their nuclei, and
shrink somewhat in size, and thus acquire the characters of the red disks. But Mr.
Wharton Jones has, from an extended series of observations, arrived at the conclusion
that, whilst in birds, reptiles, and fishes, the pale or lymph corpuscle, suffering merely
some alteration of form and contents, becomes the red disk, its nucleus alone is
developed into the red disk of mammalian blood. According to this view (supported
by Busk, Huxley, and Gulliver), while the red corpuscle of oviparous vertebrata is the
transformed pale corpuscle its development not proceeding beyond this stage the
non-nucleated red disk of man and mammalia is, on the other hand, considered to be,
not the homologue of the oval nucleated red disk of the oviparous vertebrata, but
that of its nucleus. It is not within the scope of this work to enter upon a discussion
of the relative merits of these opinions, and the reader is referred to physiological
works for a consideration of these and other views adopted by various authors upon
the point at issue.
EPIDERMIC, EPITHELIAL, OR CUTICULAR TISSUE.
General nature and situation. It is well known, that when the skin is
blistered, a thin, and nearly transparent membrane, named the cuticle or
epidermis, is raised from its surface. In like manner, a transparent film
may be raised from the lining membrane of the mouth, similar in nature to
the epidermis, although it has in this situation received the name of
"epithelium;" and under the latter appellation, a coating of the same
kind exists on nearly all free surfaces of the body. It is true that in
many situations the epithelium cannot be actually raised from the subjacent
surface as a coherent membrane, still its existence as a continuous coating
can be demonstrated ; and, although in different parts it presents important
differences, it has in all cases the same fundamental structure, and its
several varieties are connected by certain common characters.
The existence of a cuticular covering in one form or other, has been
demonstrated in the following situations : viz. 1. On the surface of the
skin. 2. On mucous membranes ; a class of membranes to be afterwards
described, which line those internal cavities and passages of the body that
open exteriorly, viz., the alimentary canal, the lachrymal, nasal, tympanic,
respiratory, urinary, and genital passages ; as well as the various glandular
recesses and ducts of glands, which open into these passages or upon the
surface of the skin. 3. On the inner or free surface of serous membranes,
which line the walls of closed cavities in the head, chest, abdomen, and
other parts. 4. On the membranes termed synovial within the joints.
5. On the inner surface of the blood-vessels and lymphatics.
Structure in general. This tissue has no vessels, and, except in certain
parts of the organs of the senses, is devoid of nerves, and of sensibility ; it,
nevertheless, possesses a decidedly organised structure. Wherever it may
exist, it is formed essentially of nucleated cells united together by cohesive
matter, often in too small quantity to be apparent. The cells, in
whatever way they may be produced, make their appearance first in the
deepest part of the structure, where they receive material for growth from
the blood-vessels of the subjacent tissue ; then, usually undergoing con-
siderable changes in size, figure, and consistency, they gradually rise to the
surface, where, as shown at least in various important examples, they are
thrown off and succeeded by others from beneath. In many situations the
cells form several layers, in which they may be seen in different stages of
progress, from their first appearance to their final desquamation. The
layer or layers thus formed, take the shape of the surface to which they are
SCALY EPITHELIUM.
liii
Fig. XX.
applied, following accurately all its eminences, depressions and inequalities.
Epithelium when destroyed or cast off, is, for the most part, very readily
regenerated.
In accordance with the varied purposes which the epithelium is destined
to fulfil, the cells of which it is composed come to differ in different situa-
tions, in figure and size, in their position in respect of each other,
their degree of mutual cohesion, and in the nature of the matter they
contain, as well as in the vital endowments which they manifest ; and,
founded on these modifications of its constituent cells, or, at any rate, those
forming the superficial layer, four principal varieties of epithelium have been
recognised, namely, the scaly, the columnar, the spheroidal, and the ciliated,
each of which will now be described in particular.
It may first be remarked, however, that amidst these changes the nucleus
of the cell undergoes little alteration, and its characters are accordingly
remarkably uniform throughout. It is round or oval, and more or less
flattened ; its diameter measures from ffjpnpth to ^y 1 ^ 0th of an inch, or
more. Its substance is insoluble in acetic acid, and colourless, or but
slightly tinted. It usually contains one or two nucleoli, distinguished by
their strong dark outline ; and a variable number of more faintly marked
granules irregularly scattered. For the most part, the nucleus is persistent,
but in some cases it disappears from the cell.
Scaly Epithelium. The scaly, lamellar,
tabular, or flattened epithelium (comprehend-
ing, in part, the pavement or tesselated
epithelium of the German anatomists). In
this variety the epithelium particles have the
form of small angular plates, or thin scales ;
in some situations forming a single thin layer,
in others accumulating in many superimposed
strata, so as to afford to the parts they cover
a defensive coating of considerable strength and
thickness.
As a simple layer, it is found on the serous,
and some synovia! membranes, the inner surface
of the heart, blood-vessels and absorbents ;
also partly lining the cerebral ventricles and
covering the choroid plexuses ; on certain parts
within the eye and ear, and in some gland-ducts.
If the surface of the peritoneum, pleura,
pericardium, or other serous membrane be
gently scraped with the edge of a knife, a
small quantity of soft matter will be brought away, which, when examined
with the microscope, will be found to contain little shred-like fragments of
epithelium, in which a few of its constituent particles still hold together, like
the pieces composing a mosaic work (fig. xx.). These particles, which are
flattened cells, have for the most part a polygonal figure, and are united to
each other by their edges. Each has a nucleus, apparently in or near the
centre. The addition of weak acetic acid renders the angular outline of the
cells as well as the nucleus more distinct. The cells differ somewhat in size
on different parts of the serous membrane ; and those which cover the
plexus choroides send downward short, pointed, transparent processes to-
wards the subjacent tissue.
The epithelium of the vascular system resembles in many parts that of
Fig. XX. FRAGMENT OF En
THELIUM FROM A SEROUS
MEMBRANE (PERITONEUM) ;
MAGNIFIED 410 DIAMETERS.
a, cell ; b,
cleoli (Henle).
nucleus ; c, nu-
liv
SCALY EPITHELIUM.
Fig. XXI.
the serous membranes ; but in some situations, and especially in the arteries,
the flattened cells, together with their nuclei, assume an oblong fusiform
figure, and sometimes their outline becomes indistinct from blending of
neighbouring cells.
A scaly epithelium, in which the cells form several layers, (thence named
stratified) covers the skin, where it constitutes the scarf-skin or
epidermis, which, together with the hairs and nails, will be afterwards more
fully described. In this form it exists, also, on the conjunctival covering
of the eyeball ; on the membrane of the nose for a short distance inwardly ;
on the tongue and the inside of the mouth, throat, and gullet ; on the vulva
and vagina, extending some way into the cervix of the uterus ; also (in both
sexes), on a very small extent of the membrane of the urethra, adjoining the
external orifice. It is found, also, on the synovial membranes which Hue
the joints. Its principal use, no doubt,
is to afford a protective covering to
these surfaces, which are almost all
more or less exposed to friction.
The cells in this sort of epithelium
become converted into broad thin
scales, from 8 -}^ to - 5 ^ of an inch in
diameter, which are loosened and cast
off at the free surface. Such scales,
both single and connected in little
patches, may be at all times seen with
the microscope in mucus scraped from
the inside of the mouth, as shown in
fig. xxi. ; but to trace the progressive
changes of the cells, they must be suc-
cessively examined at different depths from the surface, and the epithelium
must also be viewed in profile, or in a perpendicular section, as exhibited in
fig. xxn.
The deepest cells, or those next the subjacent tissue, are sometimes
Fig. XXII.
Fig. XXL EPITHELIUM-SCALES PROM
THE INSIDE OF THE MOUTH ; MAGNI-
FIED 260 DIAMETERS (Henle).
Fig. XXII. EPITHELIUM FROM THE CONJUNCTIVA OF THE CALF, FOLDED so THAT THE
FREE SURFACE FORMS THE UPPER BORDER OF THE FIGURE, AND RENDERED TRANS-
PARENT BY ACETIC ACID.
1, 2, 3, 4, 5, progressive flattening of the cells as they rise to the surface. The
outline figures represent single cells from different depths, viewed on their surface ; and
at 4' and 5', edgeways. Magnified 410 diameters (chiefly after Henle).
SCALY EPITHELIUM.
Iv
rounded or spheroidal in shape (fig. xxii., 1 ), and but little larger than their
nuclei ; but more commonly the undermost layer is formed (as shown in
fig. xxiii.) of oblong cells, which are placed vertically, and may be larger in
size than the round cells which lie immediately over them. Such oblong
vertical cells occur in the undermost layer of the epidermis, and similarly in
the epithelium of the cornea and of various parts of the mucous membranes.
Sometimes they form two or three successive rows. Higher up in the mass
the cells are enlarged ; they have a globular or oval figure, and are filled
with soft matter ; thv.j>ext become flattened, but still retain their round
or oval outline ; then the continued flattening causes their opposite sides to
meet and cohere, except where separated by the nucleus, and they are at
length converted into thin
scales, which form the upper- p i(r
most layers. While they are
undergoing this change of
figure, their substance becomes
more firm and solid, and their
chemical nature is more or
less altered ; for the cell-
membrane of the softer and
more deep-seated cells may be
dissolved by acetic acid, which
is not the case with those
nearer the surface. The nu-
cleus at first enlarges, as well
as the cell, but in a much
less degree. The scales near the surface overlap a little at their edges, and
their figure is very various ; somewhat deeper it is mostly polygonal, and
more uniform.
In various parts, the more superficial and denser layers of the scaly
epithelium can be readily separated from the deeper, more recently formed,
softer and more opaque part which lies underneath ; so that the latter
is often distinguished as the Malpighian or mucous layer (stratum or rete
mucosum), although it is now well understood not to be an independent
membrane. This point will be again noticed in treating of the skin.
Fig. XXIII. DIAGRAM OF SECTION OF EPITHE-
LIUM, IN WHICH THE UNDEUMOST CELLS ARE
OBLONG AND VERTICAL.
Furrowed and sinnous cells of epithelium. It was long since noticed by Henle
that the flattened cells sometimes present a striated appearance and quite recently
Max Schultze and Virchow have described cells marked on the surface with parallel
ridges and furrows (Rlffzelleii), and others (Stachelzellen) covered with spines, and
therefore presenting a fringed or denticulate border (fig. xxiv.). Both varieties have
been found in the epithelium of the tongue, lips, and conjunctiva, and in the
epidermis ; and in all cases are confined to the deeper or Malpighian layers. Similar
cells have been found in epithelial cancer and in cancroid tumours ; and flattened
cells, beset with minute spines on their free surface, have recently been noticed (by
Broueff and Eberth) in the epithelium covering the inner surface of the cat's
amnion.
In thin vertical sections of the epidermis of the fingers I have seen what appeared
to be cells with a deeply serrated outline, in the Malpighian layer, but I have not
been able to separate them so as to examine them singly.
Growth. It must be admitted that the continued production of new cells by which
this and other kinds of epithelium are maintained, is not yet thoroughly understood.
It was at one time commonly believed that the cells which go through the changes
of form and position already described, are formed from nuclei arising by independent
formation in a blastema supplied by the subjacent vascular membrane; but it is now
COLUMNAR EPITHELIUM.
Fig. XXIV.
more generally held that the new epithelium-cells are produced by division of pre-
existing cells in the lowermost stratum. In the earliest condition of the embryo
there are special layers of cells, derived from the primitive embryonic cells, set aside
for the production of the epidermis and of the intestinal and glandular epithelium ;
and it is quite conceivable, and by some histologists considered most probable, that
the subsequent generations of epidermic and epithelial
cells by which the tissue is throughout life main-
tained, are derived by unbroken descent from the
original embryonic stratum. At the same time, the
reproduction of epidermis in cicatrices after wide
and deep destruction of the subjacent skin, implies
some other source of new cells ; unless indeed it be
supposed that the new cuticle grown exclusively from
the old at the circumference of the sore. Setting
aside this supposition, we might conceive the new
cells to come from the connective-tissue corpuscles of
the granulating surface of the new-growing skin ; and
a recent writer (Dr. Otto Weber) describes such mode
of reproduction of epidermis as actually observed by
him in the healing of wounds ; moreover, it may be
questioned whether, in certain situations, this may
not be the regular process by which the growth of
epithelium is maintained.
When the lowermost cells are elongated and vertical,
it is difficult to conceive that they rise up as such,
and take their place in the upper strata ; for the cells
next above them are spheroidal in shape and smaller
in size. It seems more likely that they divide into
It might be supposed that an oblong vertical cell,
by division of its nucleus and separation of the upper portion of the cell-body,
produces a new and smaller cell, which rises up, while the parent cell maintains
its place, and lengthens out again for a repetition of the process. Dr. Schneider*
describes appearances actually observed by him in the epithelium covering the front
of the cornea, which seem to indicate a process of this kind ; but much more extended
observations are required to settle the point. I have seen cells with double or divided
nuclei in the epithelium of the bladder, but not confined to the deep strata ; on
the other hand, I have never
Fig. XXIV. SPINOUS CELLS
FROM THE MALPIGHIAN
LAYER OF THE HUMAN EPI-
DERMIS J ABOUT j^ INCH
IN DIAMETKR (after M.
Schultze, Virch. Arch. vol.
30).
or produce the smaller cells.
Fig. XXV.
been able to perceive indica-
tions of division in the deep
vertical cells of the epider-
mis ; at the same time it is
plain that the latter are not
mere nuclei imbedded in a
blastema ; the nucleus is
surrounded by a tolerably
well-marked cell-body, which
has a deeply denticulate or
fringed border at the part
turned towards the corium.
Columnar Epithelium
(Cylinderepithelium of
Germ. Anat.). In this
variety (figs. xxv. and
xxvi.), the constituent
cells are elongated in a direction perpendicular to the surface of the membrane,
so as to form short upright columns, which may be of the same thickness
Fig. XXV. A, COLUMNS OF EPITHELIUM FROM THE
INTESTINE MAGNIFIED; B, VIEWED BY THEIR BROAD
FREE EXTREMITY J C. SEEN IN A TRANSVERSE SECTION
OF AN INTESTINAL VILLUS (from Henle).
* Wiirzb. Naturwiss : Zeitschrift, vol. iii. 1862.
COLUMNAR EPITHELIUM. Ivii
throughout, but are more frequently smaller or even pointed at their
lower or attached extremity, and broader at the upper (fig. xxv. A).
They are mostly flattened on their sides, by which they are in mutual
apposition, at least in their upper and broader part, and have, therefore,
so far a prismatic figure, their broad flat ends appearing at the surface of
the epithelium in form of little polygonal areas (fig. xxv. B.) The nucleus,
usually oval, and containing a nucleolus, is placed near the middle of the
column, and is often so large in proportion to the cell, as to cause a bulging
at that part ; in which case the height of the nucleus differs in contiguous
columns, the better to allow of mutual adaptation.
This variety of epithelium is
confined to mucous membranes. Fi gt XXVI.
It is found in the stomach ; on
the mucous membrane of the
intestines in its whole extent ;
in the whole length of the
urethra, except a small part at
the orifice. It extends along
the ducts of the greater number
of glands, whether large or
small, which open on the mu- Fig. XXVI. EPITHELIUM PROM INTESTINAL
cous membrane, but not through VILLUS OP A RABBIT; MAGNIFIED 300 DIA-
their entire length ; for, at their
extremities, these ducts have for , Thick border (from Kolliker).
the most part an epithelium of
a different character. It covers also the inner membrane of the gall-bladder.
In these different situations the cells form but a single layer. On the
proper olfactory region of the nasal mucous membrane there is a modification
of the columnar epithelium, in which the cells, tinged with brownish yellow
pigment, are associated with the terminations of the olfactory nerves, and
present other peculiarities, which will be noticed in the special description of
the organ of smelling.
The substance ordinarily contained in the columnar cells has a faintly granular
aspect, and consists chiefly of mucus, which is no doubt produced in the cell. Under
exposure to water this mucus swells up and escapes in form of a pellucid drop
(fig. xxvu., a, 6). During digestion of food containing oil or fat, the cells of the
intestinal epithelium are often found to be filled with minute fat-molecules ; as if
they had some part to perform in the absorption of that aliment. The wall of the
cell forming the basis or free end is comparatively thick (fig. xxvi., a), and is marked
by fine parallel lines running perpendicular to the surface (fig. xxvu., 1, 2). The
thick, striated border is superadded, as it were, to the thin proper wall forming the
base of the cell, and is regarded by Kolliker, who first pointed out its striated
character, as an excreted product of the cell, deposited upon its outer surface, as
occurs in the cuticular structures of many of the inferior animals. As to the striation,
it might no doubt be produced by a fine columnar or fibrous structure, but most
observers agree with Kolliker in ascribing it to fine tubular passages perforating the
cell-wall ; and it is further supposed that such porous structure would account for the
assumption of fat-molecules or other minutely divided matters into the cell, and may
be subservient to an absorptive function in cells so constituted. It must be stated,
however, that a thickened striated border has been since observed in various other
epithelium cells which are not so obviously connected with the function of absorption,
such as those lining the biliary and urinary passages, and the parotid and pancreatic
ducts.
As fat, in a state of minute division, is undoubtedly taken into the epithelium-cells
of the intestinal villi, and disappears from them again, it was natural to look for some
Iviii
CILIATED EPITHELIUM.
Fig. XXVII.
Fig. XXVII. CELLS OP INTESTINAL EPI-
THELIUM OF BABBIT, TREATED WITH
WATER ; MAGNIFIED 350 DIAMETERS.
1 and 2 show striated or porous border,
somewhat swollen by imbibition; a, b,
pellucid drops of mucus which have escaped
from the cells (from Kolliker).
way by which it might be conveyed from the cells into the lacteal vessels ; but
hitherto the search has not been successful. The alleged communication of the cells
in question with lacteal vessels, through
the intermedium of connective-tissue-
corpuscles, rests on no sufficient evi-
dence. It is true that processes, like
roots, have in some cases been observed
running down from columnar cells into
the subjacent tissue, and in the epithe-
lium of the olfactory membrane these
radical processes are long and ramified ;
but the connection of these prolongations
with connective-tissue-corpuscles is as
yet a matter of presumption only ;
although there is proof of such con-
nection in the case of some ciliated
epithelium-cells; and it is material to ob-
serve that the intestinal epithelium,
when examined fresh and without the
aid of condensing reagents, shows no
such processes.
The particles of columnar epithelium are undoubtedly subject to shedding and
renovation ; but although various suppositions have been hazarded as to the mode in
which this is effected, it must be admitted that no satisfactory account has been given
of the process. According to Donders and Kolliker, the columnar cells on the villi
appear occasionally to cast off a part from their upper end, with subsequent repara-
tion of the loss. That is, a cell enlarges and a second nucleus appears ; the upper and
broader part, with one nucleus and much of the cell-contents, separates, and the lower
remaining portion, with its nucleus, grows again to the natural size. The extruded
portion is supposed to become a mucus-corpuscle.
Spheroidal Epithelium. Tn this variety, the cells for the most part retain
their primitive roundness, or, being flattened where they touch, acquire a
polyhedral figure, in which no one dimension remarkably predominates.
Hence the above term was applied to this form of epithelium by Mr.
Bowman. But in some places the cells show a tendency to lengthen into
columns and in others to flatten into tables, especially when this epithelium
approaches the confines of one or other of the preceding varieties ; in such
cases it has been named transitional ; moreover, when the scaly and columnar
varieties border upon one another, the figure of their particles is gradually
changed, presenting various intermediate forms ;
in other words, the epithelium there puts on the
transitional character, though it may be only
for a very small space.
The spheroidal epithelium is found in the
excretory ducts of the mammary, perspiratory,
and of many mucous glands, and a modification
of the spheroidal epithelium lines the inmost
secreting cavities, or commencing ducts of
glands generally (fig. xxvm.). In this last-
mentioned situation, where it is sometimes dis-
tinguished by the name of glandular epithelium t
the nucleated cells contain a large proportion of
fine granular matter ; in some cases even, the peculiar ingredients of the
secretion may be recognised in them ; and it is conceived, that they have a
considerable share in preparing or separating these matters from the blood.
Ciliated Epithelium. In this form of epithelium, the particles, which are
Fig. XXVIII.
Fig. XXVIII CELLS FROM
THE LlVER MAGNIFIED (Dr.
Baly).
CILIATED EPITHELIUM. lix
generally columnar, bear at their free extremities little hair-like pro-
cesses, which are agitated incessantly during life, and for some time after
death, with a lashing or vibrating motion. These minute and delicate
moving organs are named cilia. They have uo\v been discovered to
exist very extensively throughout the animal kingdom ; and the move-
ments which they produce are subservient to very varied purposes in the
animal economy.
In the human body the ciliated epithelium occurs in the following parts,
viz. : 1. On the mucous membrane of the air passages and its pro-
longations. It commences at a little distance within the nostrils, covers
the membrane of the nose and of the adjoining bony sinuses, and extends
up into the nasal duct and lachrymal sac. From the nose it spreads back-
wards a certain way on the upper surface of the soft palate, and over the
upper or nasal region of the pharynx ; thence along the Eustachian tube
and lining membrane of the tympanum, of which it covers the greater part.
The lower part of the pharynx is covered by scaly epithelium as already
mentioned ; but the ciliated epithelium begins again in the larynx a little
above the glottis, and continues throughout the trachea and the bronchial
tubes in the lungs to their smallest ramifications. 2. On the mucous lining
of the uterus, commencing at the middle of the cervix and extending along
the Fallopian tubes, even to the peritoneal surface of the latter at their
ninbriated extremities. 3. Lining the vasa efferentia, coni vasculosi, and
first part of the excretory duct of the testicle. 4. To a large extent on
the parietes of the ventricles of the brain, and throughout the central canal
of the spinal cord.
In other mammiferous animals, as far as examined, cilia have been found
in nearly the same parts. To see them in motion, a portion of ciliated
mucous membrane may be taken from the body of a recently killed quad-
ruped. The piece of membrane is to be folded with its free or ciliated
surface outwards, placed on a slip of glass, with a little weak salt water or
serum of blood, and covered with a bit of thin glass or mica. When it is
now viewed with a magnifying power of 200 diameters or upwards, a very
obvious agitation will be perceived on the edge of the fold, and this
appearance is caused by the moving cilia with which the surface of the
membrane is covered. Being set close together, and moving simultaneously
or in quick succession, the cilia, when in brisk action, give rise to the
appearance of a blight transparent fringe along the fold of the membrane,
agitated by such a rapid and incessant motion, that the single threads which
compose it cannot be perceived. The motion here meant, is that of the
cilia themselves ; but they also set in motion the adjoining fluid, driving it
along the ciliated surface, as is indicated by the agitation of any little
particles that may accidentally float in it. The fact of the conveyance of
fluids and other matters along the ciliated surface, as well as the direction
in which they are impelled, may also be made manifest by immersing the
membrane in fluid, and dropping on it some finely pulverised substance
(such as charcoal in fine powder), which will be slowly but steadily carried
along in a constant and determinate direction ; and this may be seen with
the naked eye, or with the aid of a lens of low power.
The ciliary motion of the human mucous membrane is beautifully seen
on the surface of recently extracted nasal polypi ; and single ciliated parti-
cles, with their cilia still in motion, are sometimes separated accidentally
from mucous surfaces in the living body, and may be discovered in the dis-
charged mucus ; or they may even be purposely detached by gentle abrasion.
CILIATED EPITHELIUM.
But the extent and limits of the ciliated epithelium of the human body have
been determined chiefly from its anatomical characters.
Cilia have now been shown to exist in almost every class of animals,
from the highest to the lowest. The immediate purpose which they serve
is, to impel matter, generally more or less fluid, along the surfaces on which
they are attached ; or, to propel through a liquid medium the ciliated
bodies of minute animals, or other small objects on the surface of which
cilia are present ; as is the case with many infusorial animalcules, in which
the cilia serve as organs of locomotion like the fins of larger aquatic animals,
and as happens, too, in the ova of many vertebrate as well as invertebrate
animals, where the yelk revolves in its surrounding fluid by the aid of cilia
on its surface. In many of the lower tribes of aquatic animals, the cilia
acquire a high degree of importance : producing the flow of water over the
surface of their organs of respiration, indispensable to the exercise of that
function ; enabling the animals to seize their prey, or swallow their food,
and performing various other offices of greater or less importance in their
economy. In man, and the warm-blooded animals, their use is apparently to
impel secreted fluids or other matters along the
ciliated surface, as, for example, the mucus of
Fig. XXIX.
the windpipe and nasal sinuses, which they
carry towards the outlet of these cavities.
The cells of the ciliated epithelium contain
nuclei, as usual ; they have most generally an
elongated or prismatic form (fig. xxix.), like
the particles of the columnar epithelium, which
they resemble too in arrangement, but are
often of greater length and more slender and
pointed at their lower end. The cilia are
attached to their broad or superficial end,
each columnar particle bearing a tuft of these
minute hair-like processes. In some cases, the
cells are spheroidal in figure, the cilia being
still, of course, confined to that portion of the
cell which forms part of the general surface of
the epithelial layer, as shown in fig. xxx., which represents such cells from
the epithelium of the frog's mouth. In man this form occurs in the ciliated
epithelium of the cerebral ventricles and tympa-
num, where the cells form but a single stratum.
The columnar ciliated epithelium also may exist as
a simple layer, as in the uterus and Fallopian tubes,
the finest ramifications of the bronchia, and the
central canal of the spinal cord ; but in various
other parts as the nose, pharynx, Eustachian
tube, the trachea and its larger divisions there
is a layer of elongated cells beneath the superficial
ciliated range, filling np the spaces between the
pointed extremities of the latter, and beneath
this is an undermost layer, formed of small
rounded cells (fig. xxxi.). Probably the sub-
jacent cells acquire cilia, and take the place of
ciliated cells which are cast off ; but the mode of
renovation of ciliated epithelium is not yet fully understood.
The relation of the ciliated, as well as other epithelium-cells, to the connective tissue
Fig. XXIX. COLUMNAR
CILIATED EPITHELIUM-CELLS
FROM THE HUMAN NASAL
MEMBRANE; MAGNIFIED 300
DIAMETERS.
Fig. XXX.
Fig. XXX. SPHEROIDAL
CILIATED CELLS FROM
THE MOUTH OP THE
FROG ; MAGNIFIED 300
DIAMETERS.
CILIATED EPITHELIUM.
Ixi
Fig. XXXT.
of the subjacent membrane, has much engaged attention since the importance of the
connective-tissue-eorpuscles has
come to be recognised ; and a
strong impression or belief pre-
vails that such epithelium-cells
are structurally connected by
prolongations from their lower
ends with these corpuscles, and
genetically related to them.
As a matter of observation,
such anatomical connection is
affirmed on excellent authority
(Lockhart Clarke, Gerlach, and
others) in reference to the
columnar ciliated epithelium of
the central canal of the spinal
cord and the Sylvian aqueduct,
but the evidence in other cases
is not so satisfactory.
Fig. XXXI. CILIATED EPITHELIUM FROM THE
HUMAN WINDPIPE; MAGNIFIED 350 DIAMETERS.
a, b, subjacent membrane ; c, lowermost or round
cells; d, middle layer of oval cells; e, superficial or
ciliated cells (from Kolliker).
The cilia themselves differ
widely in size in different
animals, and they are not
equal in all parts of the same animal. In the human windpipe they
measure ^oVoth to o-rVljth ^ an ^ nc ^ ^ length. ; but in many invertebrate
animals, especially such as live in salt water, they are a great deal larger.
In figure they have the aspect of slender, conical, or slightly flattened fila-
ments ; broader at the base, and usually pointed at their free extremity.
Their substance is transparent, soft, and flexible. It is to all appearance
homogeneous, and no fibres, granules, or other indications of definite
internal structure, have been satisfactorily demonstrated in it.
Motion of the cilia. The manner in which the cilia move, is best seen
when they are not acting very briskly. Most generally they seem to execute
a sort of fanning or lashing movement ; and when a number of them
perform this motion in regular succession, as is generally the case, they give
rise to the appearance of a series of waves travelling along the range of
cilia, like the waves caused by the wind in a field of corn. When they are
in very rapid action the undulation is less obvious, and, as Henle remarks,
their motion then conveys the idea of swiftly running water. The undu-
lating movement may be beautifully seen on the gills of a mussel, and on
the arms of many polypes. The undulations, with some exceptions, seem
always to travel in the same direction on the same parts. The impulsion,
also, which the cilia communicate to the fluids or other matters in contact
with them, maintains a constant direction; unless in certain of the infusoria,
in which the motion is often variable and arbitrary in direction, and has
even been supposed to be voluntary. Thus in the windpipe of mammalia,
the mucus is conveyed upwards towards the larynx, and, if a portion of the
membrane be detached, matters will still be conveyed along the surface of
the separated fragment in the same direction relatively to that surface, as
before its separation.
The persistence of the ciliary motion for some time after death, and the
regularity with which it goes on in parts separated from the rest of the body,
sufficiently prove that, with the possible exceptions alluded to, it is not
under the influence of the will of the animal nor dependent for its produc-
tion on the nervous centres, and it does not appear to be influenced in any
Ixii CILIATED EPITHELIUM.
way by stimulation or sudden destruction of these centres. The time which
it continues after death or separation differs in different kinds of animals,
and is also materially influenced by temperature and by the nature of the
fluid in contact with the surface. In warm-blooded animals the period
varies from two or three hours to two days, or even more ; being longer in
summer than in the cold of winter. In frogs the motion may continue four
or five days after the destruction of the brain ; and it has been seen in the
gullet of the tortoise fifteen days after decapitation, continuing seven days
after the muscles had ceased to be irritable.
With the view of throwing further light on the nature of this remarkable
kind of motion, experiments have been made to ascertain the effect produced
on it by different physical chemical and medicinal agents ; but, so far as
these experiments have gone, it would seem that, with the exception of
moderate heat and cold, alkaline solutions, chloroform vapour, and perhaps
some other narcotics, these agents affect the action of the cilia only in so
far as they act destructively on their tissue.
The effect of change of temperature is different in warm and in cold-blooded animals.
In the former the motion is stopped by a cold of 43 F., whereas in the frog and river
mussel it goes on unimpaired at 32 F. E. H. Weber has made the interesting
observation that, in ciliated epithelium particles detached from the human nasal
membrane, the motion which has become languid or quiescent from the cold may be
revived by warmth, such as that of the breath, and this several times in succession.
A moderately elevated temperature, say 100 F., does not affect the motion in cold-
blooded animals ; but, of course, a heat considerably higher than this, and such as to
alter the tissue, would put an end to it in all cases. Electric shocks, unless they
cause abrasion of the ciliated surface (which is sometimes the case), produce no
visible effect ; and the same is true of galvanic currents. Fresh water, I find,
arrests the motion in marine mollusca and in other salt-water animals in which
I have tried its effect ; but it evidently acts by destroying both the form and sub-
stance of the cilia, which in these cases are adapted to a different medium. Most of
the common acid and saline solutions, when concentrated, arrest the action of the
cilia instantaneously in all animals ; but dilution delays this effect, and when carried
farther, prevents it altogether ; and hence it is, probably, due to a chemical altera-
tion of the tissue. Virchow has observed that a solution of either potash or soda
will revive the movement of cilia after it has ceased. Narcotic substances, such as
hydrocyanic acid, salts of morphia and strychnia, opium and belladonna, are said by
Purkinje and Valentin to have no effect, though the first-named agent has certainly
appeared to me to arrest the motion in the river-mussel. In confirmation of an
observation of Professor Lister,* I find that exposure for a few moments to the
vapour of chloroform arrests ciliary action, and that the motion revives again if the
application of the vapour is discontinued.
Bile stops the action of the cilia, while blood prolongs it in vertebrated animals ;
but the blood or serum of the vertebrata has quite an opposite effect on the cilia of
invertebrate animals, arresting their motion almost instantaneously.
It must be confessed that the nature and source of the power by which
the cilia act are as yet unknown ; but whatever doubt may hang over this
question, it is plain that each ciliated cell is individually endowed with the
faculty of producing motion, and that it possesses in itself whatever organic
apparatus and whatever physical or vital property may be necessary for that
end ; for single epithelium cells are seen to exhibit the phenomenon long
after they have been completely insulated.
Without professing to offer a satisfactory solution of a question beset with so much
difficulty, it seems, nevertheless, not unreasonable to consider the ciliary motion as
* Phil. Trans. 1858, p. 690, where will be found other valuable observations en the
effect of external agents on ciliary action.
PIGMENT. Ixiii
being probably a manifestation of that property on which the more conspicuous
motions of animals are known to depend, namely, vital contractility ; and this view-
has at least the advantage of referring the phenomenon to the operation of a vital
property already recognised as a source of moving power in the animal body. But,
assuming this view to be sound, so far as regards the nature of the motile property
brought into play, it affords no explanation of the cause by which the contractility
is excited and the cilia maintained in constant action.
It is true that nothing resembling a muscular apparatus in the ordinary sense of
the term, has been shown to be connected with the cilia, nor is it necessary to
suppose the existence of any such ; for it must be remembered that, while the organic
substance on which vital contractility depends is probably uniformly the same in
composition, it does not everywhere assume the same form and texture. The
anatomical characters of human voluntary muscle differ widely from those of most
involuntary muscular structures, and still more from the contractile tissues of
some of the lowest invertebrate animals, although the movements must in all these
cases be referred to the same principle. The heart of the embryo beats while yet
but a mass of cells, united, to all appearance, by amorphous matter, in which no
fibres are seen ; yet no one would doubt that its motions depend then on the same
property as at a later period, when its structure is fully developed.
In its persistence after systemic death and in parts separated from the rest of the
body, the ciliary motion agrees with the motion of certain muscular organs, as the
heart, for example ; and the agreement extends even to the regular or rhythmic cha-
racter of the motion in these circumstances. It is true, the one endures much longer
than the other ; but the difference appears to be one only of degree, for differences
of the same kind are known to prevail among muscles themselves. No one, for
instance, doubts that the auricle of the heart is muscular, because it beats longer after
death than the ventricle ; nor, because a frog's heart continues to act a much longer
time than a quadruped's, is it inferred that its motion depends on a power of a dif-
ferent nature. And the view here taken of the nature of the ciliary motion derives
strength from the consideration that the phenomenon lasts longest in cold-blooded
animals, in which vital contractility also is of longest endurance. In the effects of
heat and cold, as far as observed, there is also an agreement between the movement
of cilia and that of muscular parts ; while, on the other hand, it must be allowed
that electricity does not appear to excite their activity. The effects of narcotics
afford little room for inference, seeing that our knowledge of their local action on
muscular irritability is by no means exact ; but in one instance, at least, an agent,
chloroform vapour, which stops the action of the freshly excised heart of a frog,
arrests also the ciliary motion. Something, moreover, may depend on the facility or
difficulty with which the tissues permit the narcotic fluid to penetrate, which cir-
cumstance must needs affect the rapidity and extent of its operation. Again, we see
differences in the mode in which the cilia themselves are affected by the same agent ;
thus, fresh water instantly arrests their motion in certain cases, while it has no such
effect in others.
The discovery of vibrating cilia on the spores and other parts of certain crypto -
gamic vegetables may perhaps be deemed a strong argument on the opposite side :
but it is by no means proved that the sensible motions of plants (such, at least, as
are not purely physical), and those of animals, do not depend on one common vital
property.
PIGMENT.
The cells of the cuticle, and of other textures which more or less resemble
it in structure, sometimes contain a black or brown matter, which gives a
dark colour to the parts over which, the cells are spread. A well-marked
example of such pigment-cells in the human body is afforded by the black
coating which lines the choroid membrane of the eye and covers the pos-
terior surface of the iris. They are found in the epidermis of the Negro
and other dark races of mankind, and in the more dusky parts of the
Ixiv
PIGMENT.
Fig. XXXII.
A
Fig. XXXII. PIGMENT-CELLS PROM
THE CHOROID ; MAGNIFIED 370 DIA-
METERS (Henle).
A, cells still cohering, seen on their
surface ; ft, nucleus indistinctly seen.
In the other cells the nucleus is con-
cealed by the pigment granules.
B, two cells seen in profile ; a, the
outer or posterior part containing
scarcely any pigment.
cuticle of the European. In different forms also they exist on certain parts
of the investing membrane (pia mater) of the spinal cord, in the membranous
labyrinth of the ear, and (with brownish yellow pigment) on the olfactory
region of the nose.
The pigment cells of the choroid membrane (fig. xxxn.) are for the most
part polyhedral in figure, most generally six-sided, and connected together
like the pieces of a mosaic pavement ; others are spheroidal, and most of
those on the back of the iris are of
that shape. The cells contain the pig-
ment, strictly so called, which consists
of black or brown granules or mole-
cules of a round or oblong shape, and
almost too small for exact measure-
ment. These molecules are densely
packed together in some cells ; in
others they are more scattered, and
then it may be seen that there is a
certain amount of colourless matter in-
cluded along with them. When they
escape from the ruptured cells, they
exhibit very strikingly the molecular
movement ; and in consequence of this
movement the apparent figure of the
particles is subject to change. It is
worthy of remark, that when viewed
singly with a very high magnifying
power they look transparent and almost
colourless, and it is only when they are heaped together that their black-
ness distinctly appears. The cells have a colourless nucleus, which is very
generally hidden from view by the black particles. It contains a central
nucleolus.
Examined chemically, the black matter is found to be insoluble in cold
and hot water, alcohol, ether, fixed and volatile oils, acetic and diluted
mineral acids. Its colour is discharged by chlorine. The pigment of the
bullock's eye, when purified by boiling in alcohol and ether, was found by
Scherer to consist of 58 '672 carbon, 5 '962 hydrogen, 13*768 nitrogen, and
21-598 oxygen; its proportion of carbon is thus very large. Preceding
chemists had obtained from its ashes oxide of iron, chloride of sodium, lime,
and phosphate of lime.
The dark colour of the Negro is known to have its seat in the cuticle, and
chit-fly in the deeper and softer part named the rete mucosnm. It is
caused by cells containing dark-brown colouring matter, either diffused
through their substance or in form of granules, usually more densely
aggregated round the nucleus. These cells are found along with ordinary,
colourless cells, which in other respects they entirely resemble : and the
depth of tint depends on the proportion of each. It i* affirmed, on good
authority, that the nuclei of these epidermic pigment-cells are coloured, but
of this I have not been able to satisfy myself iu examinations of the Negro
skin. The dark parts of the European skin owe their colour and its dif-
ferent shades to intermixture in the cuticle of similar cells in different pro-
portions. Lastly, it cannot be doubted, that in both the coloured and white
races, the colouring matter of the skin is the same in its essential nature
as that of the choroid. In Albino individuals, both Negro and European,
ADIPOSE TISSUE.
Ixv
Fig. XXXIII.
in whom the black matter of the choroid is wanting, the cuticle and the
hair are colourless also.
In some situations the pigment-cells become irregular and jagged at their
edges, or even branch out into long irregular processes. Such ramified
cells are very common in many animals. In the human body pigment-cells
of this description are found in the dark tissue
on the outer surface of the choroid coat, lamina
fusca (fig. XXXIIL, a a), and on the pia mater
covering the upper part of the spinal cord. The
condition of the pigment in the hairs will be
afterwards described.
When the cuticle of the Negro is removed by
means of a blister, it is renewed again of its
original dark hue ; but if the skin be destroyed
to any considerable depth, as by a severe burn,
the resulting scar remains long white, though it
at length acquires a dark colour.
Uses. In the eye the black matter seems obviously
intended to absorb redundant light, and accordingly
its absence in Albinos is attended with a difficulty of
bearing a light of considerable brightness. Its uses in
other situations are not so apparent. The pigment of
the cuticle, it has been supposed, may screen the sub-
jacent cutis from the pungency of the sun's rays, but
in many animals the pigment is not only employed to
variegate the surface of the body, but attaches itself
to deep-seated parts. Thus, in the frog the branches
and twigs of the blood-vessels are speckled over with
it, and in many fish it imparts a black colour to the peritoneum and other internal
membranes.
Fig. XXXIIL RAMIFIED
' PIGMENT - CELLS, PROM
THE TISSUE OF THE CnO-
B.OID COAT OP THE EYE ;
MAGNIFIED 350 DIAME-
TERS (after Kb'lliker).
, cells with pigment ; b,
colourless fusiform cells.
ADIPOSE TISSUE.
The human body in the healthy state contains a considerable amount of
fatty matter of different kinds. Fat, as has been already stated, is found
in the blood and chyle, and in the lymph, but much more sparingly. It
exists, too, in several of the secretions, in some constituting the chief ingre-
dient ; and in one or other of its modifications it enters into the composition
of certain solid textures. But by far the greater part of the fat of the body
is inclosed in small cells or vesicles, which, together with their contained
matter, constitute the adipose tissue.
This tissue is not confined to any one region or organ, but exists very
generally throughout the body, accompanying the still more widely distri-
buted cellular or areolar tissue in most though not in all parts in which the
latter is found. Still its distribution is not uniform, and there are certain
situations in which it is collected more abundantly. It forms a considerable
layer underneath the skin, and, together with the subcutaneous areolar
tissue in which it is lodged, constitutes in this situation what has been
called the panniculus adiposus. It is collected in large quantity round
certain internal parts, especially the kidneys. It is seen filling up the
furrows on the surface of the heart, and imbedding the vessels of that organ
underneath its serous covering ; and in various other situations it is depo-
ADIPOSE TISSUE.
sited beneath the serous membranes, or is collected between their folds, as in
the mesentery and omentum, at first generally gathering along the course of
the blood-vessels, and at length accumulating very copiously. Collections
of fat are also common round the joints, lying on the outer surface of the
synovial membrane, and filling up inequalities ; in many cases lodged, like
the fat of the omentum, in folds of the membrane, which project into the
articular cavity. Lastly, the fat exists in large quantity within the bones,
where it forms the marrow. On the other hand, there are some parts in
which fat is never found in the healthy condition of the body. Thus it
does not exist in the subcutaneous areolar tissue of the eyelids and penis,
nor in the lungs, nor within the cavity of the cranium.
When subjected to the
Fig. XXXIV. microscope, the adipose
tissue (fig. xxxiv.) ia
seen to consist of small
vesicles, filled with an
oily matter, and for the
most part lodged in the
meshes of the areolar
tissue. The vesicles are
most commonly collected
into little lobular clusters,
and these again into the
little lumps of fat which
we see with the naked
eye, and which in some
parts are aggregated into
round or irregular masses
of considerable magni-
tude. Sometimes the vesicles, though grouped together, have less of a clus-
tered arrangement ; as when they collect alongside of the minute blood-
vessels of thin membranous parts.
In well-nourished bodies the vesicles or fat- cells are round or oval, unless
where packed closely together, in which case they acquire an angular figure,
and bear a striking resemblance to the cells of vegetable tissues. The
greater number of them are from 3-^3 th to ^gth ^ an i QCn i Q diameter,
but many exceed or fall short of this measurement. Each one consists of a
very delicate envelope, inclosing the oily matter, which, completely filling
the envelope, appears as a single drop. The envelope is generally quite
transparent, and apparently homogeneous in structure. In ill-nourished
bodies, and especially in those presenting serous infiltration of the tissues
(as in dropsy), different forms of fat cells are observed. (1.) Granular,
yellowish- white vesicles, containing numerous small fat-globules. (2.)
Yellow, or yellowish-red cells, filled with serum and globules of browni*h-
yellow fat. The relative proportion of the serum and fat varies ; but in all
cases of this description Kolliker states that he has discovered a nucleus and
a nucleolus. The nucleus may be seen without re-agents, but is rendered
more apparent by acetic acid. The vesicular envelope is found in different
conditions. Sometimes it is normal ; but it has been seen finer and also
thicker than usual. When thickened, it may present the appearance of
either a single or a double contour. (3.) Fatless cells, with normal or
thickened walls. (4.) Fat- cells containing crystals (probably of margaric
acid), either yellow or white in colour. At first sight these cells appear filled
Fig.
XXXIV. A SMALL CLUSTER OP FAT-CELLS J MAG-
NIFIED 150 DIAMETERS.
ADIPOSE TISSUE. Ixvii
with opaque and granular contents, but upon minute examination are seen
to contain stelliforin acicular crystals, though in some cases their aspect is
very faintly granular. It is not improbable that the crystals are formed after
death.
Schwann discovered a nucleus in the fat-cells of the embryo ; the nucleus
contains one or two nucleoli, and is attached to the inside of the cell- wall
or imbedded in its substance. Although nuclei have rarely been seen "in
the cells of well-nourished adipose tissue in after-life, they are readily
found when the fat has partially disappeared, and hence it may be inferred
that they are always present. This is corroborated by an observation of
Bruch, that the eudosmose of water always renders a nucleus apparent.
The common fat of the human body has been represented as a mixture of
a solid fatty substance named "margariu," and a liquid oily substance,
" olein ;" the suet or fat of oxen and sheep, on the other hand, consisting
chiefly of a second solid principle, " stearin," associated with olein. These
substances, margarin, olein, and stearin, are neutral bodies, and themselves
compounded of a base named " glycerine " with three fatty acids respectively,
the margaric, oleic, and stearic.
To the above reckoned neutral fats of the animal body a fourth, namely,
"palmitin," has now been added ; and they are all considered to be com-
pounds of three equivalents of acid, oleic, margaric, stearic, or palmitic,
with one equivalent of glycerine, minus six equivalents of water. They
have accordingly been named, "triolein," "trimargarin," " tristearin," and
" tripalmitin. " The triolein, or liquid fat, holds the other three in solu-
tion ; and the varying consistency of animal fats depends on the relative
proportion of the solid and liquid ingredients.
During life the oily matter contained in the cells is liquid ; but the
acicular crystalline spots which are sometimes seen after death indicate a
partial solidification of one of its constituents. This has been supposed to
be the margarin ; but it appears from its chemical relations to be most
probably margaric acid.
The fat being thus contained in closed cells, it will be readily understood
why, though liquid or nearly so in the living body, it does not shift its
place in obedience to pressure or gravitation, as happens with the water of
dropsy and other fluids effused into the interstices of the areolar tissue ;
such fluids, being unconfined, of course readily pass from one place to
another through the open meshes.
The areolar tissue connects and surrounds the larger lumps of fat, but
forms no special envelope to the smaller clusters ; and although fine fasci-
culi and filaments of that tissue pass irregularly over and through the
clusters, yet it is probable that the vesicles are held together in these
groups mainly by the fine network of capillary vessels distributed to them.
In the marrow the connective tissue is very scanty ; indeed, the fat-cells in
some parts of the bones are said to be altogether unaccompanied by connec-
tive filaments.
The adipose tissue is copiously supplied with blood-vessels. The larger
branches of these pass into the fat-lumps, where they run between the
lobules and subdivide, till at length a little artery and vein are sent to each
small lobule, dividing into a network of capillary vessels, which not only
surrounds the cluster externally, but passes through between the vesicles in
all directions, supporting and connecting them. The lymphatics of the fat,
if it really possess any, are unknown. Nor have nerves been seen to termi-
nate in it, though nerves destined for other textures may pass through it.
e 2
Ixviii ADIPOSE TISSUE.
Accordingly it has been observed that, unless when such traversing nervous
twigs happen to be encountered, a puncturing instrument may be carried
through the adipose tissue without occasioning pain.
As to the uses of the fatty tissue, it may be observed, in the first place, that it
serves the merely mechanical purpose of a light, soft, and elastic packing material
to fill vacuities in the body. Being thus deposited between and around different
organs, it affords them support, facilitates motion, and protects them from the inju-
rious effects of pressure. In this way, too, it gives to the exterior of the body its
smooth, rounded contour. Further, being a bad conductor of heat, the subcutaneous
fat must so far serve as a means of retaining the warmth of the body, especially
in warm-blooded creatures exposed to great external cold, as the whale and other
cetaceous animals, in which it forms a very thick stratum, and must prove a much
more effectual protection than a covering of fur in a watery element.
But the most important use of the fat is in the process of nutrition. Composed
chiefly of carbon and hydrogen, it is absorbed into the blood and consumed in respi-
ration, combining with oxygen to form carbonic acid and water, and thus contributing
with other hydrocarbonous matters to maintain the heat of the body ; and it is sup-
posed that when the digestive process introduces into the system more carbon and
hydrogen than is required for immediate consumption, the excess of those elements
is stored up in the form of fat, to become available for use when the expenditure
exceeds the immediate supply. According to this view, active muscular exercise,
which increases the respiration, tends to prevent the accumulation of fat by increasing
the consumption of the hydrocarbonous matter introduced into the body. Again,
when the direct supply of calorific matter for respiration is diminished or cut off by
withholding food, or by interruption of the digestive process, nature has recourse to
that which has been reserved in the form of fat ; and in the wasting of the body
caused by starvation, the fat is the part first consumed.
The use of the fat in nutrition is well illustrated by what occurs in the hedgehog
and some other hybernating animals. In these the function of alimentation is sus-
pended during their winter-sleep ; and though their respiration is reduced to the
lowest amount compatible with life, and their temperature falls, there is yet a con-
siderable amount of hydrocarbonous material provided in the shape of fat, before
their hybernation commences, to be slowly consumed during that period, or per-
haps to afford an immediate supply on their respiration becoming again active in
spring.
It has been estimated that the mean quantity of fat in the human subject is
about one-twentieth of the weight of the body, but from what has been said, it is
plain that the amount must be subject to great fluctuation. The proportion is
usually largest about the middle period of life, and greatly diminishes in old age.
High feeding, repose of mind and body, and much sleep, favour the production of
fat. To these causes must be added individual and perhaps hereditary predispo-
sition. There is a greater tendency to fatness in females than males ; also, it is said,
in eunuchs. The effect of castration in promoting the fattening of domestic animals
is well known.
In infancy and childhood the fat is confined chiefly to the subcutaneous tissue.
In after-life it is more equally distributed through the body, and in proportionately
greater quantity about the viscera. In Hottentot females fat accumulates over the
gluteal muscles, forming a considerable prominence; and, in a less degree, over the
deltoid. A tendency to local accumulations of the subcutaneous fat is known to
exist also in particular races of quadrupeds.
Development. According to Valentin, the fat first appears in the human
embryo about the fourteenth week of intra-uterine life. At this period fat
is deposited in cells already formed in the tissues. The cells first seen are
for the most part insulated, but by the end of the fifth mouth they are col-
lected into small groups. They are also at first of comparatively small size.
As already stated, the foetal fat- cells in their early condition contain a
nucleus which is afterwards hidden from view.
CONNECTIVE TISSUE. Ixix
It has been a question whether, when the fat undergoes absorption, the vesicles are
themselves consumed along with their contents. Dr. W. Hunter believed that they
still remained after being emptied ; he was led to this opinion by observing the con-
dition of the areolar tissue in dropsical bodies from which the fat had disappeared,
there being in such cases a marked difference in aspect between the parts of that
tissue which had originally contained fat and those which had not, which difference
he attributed to the persistence of the empty fat-vesicles. Gurlt states that the fat-
cells in emaciated animals are filled with serum, and this statement is fully confirmed
by the observations of Kb'lliker, Todd and Bowman, myself, and others.
CONNECTIVE TISSUE.
This substance consists of fibres of two kinds, more or less amorphous
matter, and peculiar corpuscles. By means of its fibres it serves in the
animal body as a bond of connection of different parts ; also as a covering
or investment to different organs, not only protecting them outwardly, but,
in many cases entering into their structure and connecting and supporting
their component parts. The corpuscles, on the other hand, are destined for
other than mechanical purposes ; they appear to be essentially concerned in
the nutrition and reparation of tissues.
Three principal modifications or varieties of connective tissue have long
been recognised, consisting of the same structural elements but in widely
different proportions, and thereby exhibiting a difference in their grosser or
more obvious characters and physical properties. They are known as the
areolar, the./i&rous, and the elastic tissues, and will be now severally treated
of. Without disregarding the alliance of cartilage and bone to the connec-
tive tissues, we shall not, in imitation of some respected authorities, include
them in the same group ; but there remain certain forms of tissue, occurring
locally, or met with as constituents of other textures, which properly belong
to this head, and will be briefly considered in a separate section as sub-
ordinate varieties of connective tissue.
Cartilage and bone are included in the group of connective tissues or connective
substances by several eminent German histologists, and present undoubted points
of relationship with these tissues, both in their nature and the general purpose
which they serve in the animal frame. Thus, yellow cartilage shows an unmistakable
transition to elastic connective tissue, as fibro-cartilage does, even more decidedly, to
white fibrous tissue. Moreover, the animal basis of bone agrees entirely in chemical
composition, and^ in many points of structure, with the last-named tissue. Still,
when it is considered that cartilage, in its typical form, consists of a quite different
chemical substance, chondrin, and that bone is characterised by an impregnation of
earthy salts, it seems more consistent with the purpose of histological description to
recognise cartilage and bone as independent tissues. As to their community of
origin, little stress need be laid on it as a basis of classification, seeing that the origin
of blood-vessels, nerves, and muscles, may be traced up to protoplasm-cells, to all
appearance similar to those that give rise to the connective tissues, and belonging to
the same embryonic layer.
THE AREOLAR TISSUE.
If we make a cut through the skin and proceed to raise it from the sub-
jacent parts, we observe that it is loosely connected to them by a soft
filamentous substance, of considerable tenacity and elasticity, and having,
when free from fat, a white fleecy aspect ; this is the substance known by
the names of "cellular," "areolar," "filamentous," "connective," and
b:x AREOLAR TISSUE.
"reticular" tissue; it used formerly to be commonly called "cellular
membrane." In like manner the areolar tissue is found underneath the
serous and mucous membranes which are spread over various internal sur-
faces, and serves to attach those membranes to the parts which they line or
invest ; and as under the skin it is named "subcutaneous," so in the last-
mentioned situations it is called "subserous" and "submucous" areolar
tissue. But on proceeding further we find this substance lying between the
muscles, the blood-vessels, and other deep-seated parts, occupying, in short,
the intervals between the different organs of the body where they are not
otherwise insulated, and thence named " intermediate ; " very generally,
also, it becomes more consistent and membranous immediately around these
organs, and, under the name of the " investing " areolar tissue, affords each
of them a special sheath. It thus forms inclosing sheaths for the muscles,
the nerves, the blood-vessels, and other parts. Whilst the areolar tissue
might thus be said in some sense both to connect and to insulate entire
organs, it also performs the same office in regard to the finer parts of which
these organs are made up ; for this end it enters between the fibres of the
muscles, uniting them into bundles ; it connects the several membranous
layers of the hollow viscera, and binds together the lobes and lobules of
many compound glands ; it also accompanies the vessels and nerves within
these organs, following their branches nearly to their finest divisions, and
affording them support and protection. This portion of the areolar tissue
has been named the " penetrating," " constituent," or " parenchymal. "
It thus appears that the areolar is one of the most general and most
extensively distributed of the tissues. It is, moreover, continuous through-
out the body, and from one region it may be traced without interruption
into any other, however distant ; a fact not without interest in practical
medicine, seeing that in this way dropsical waters, air, blood, and urine,
effused into the areolar tissue, and even the matter of suppuration, when
not confined in an abscess, may spread far from the spot where they were
first introduced or deposited.
On stretching out a portion of areolar tissue by drawing gently asunder
the parts between which it lies, it presents an appearance to the naked eye
of a multitude of fine soft elastic threads, quite transparent and colourless,
like spun glass ; these are intermixed with fine transparent films, or
delicate membranous laminae, and both threads and laminae cross one
another irregularly and in all imaginable directions, leaving open interstices
or areolse between them. These meshes are, of course, more apparent when
the tissue is thus stretched out ; it is plain also that they are not closed
cells, as the term " cellular tissue " might seem to imply, but merely inter-
spaces, which open freely into one another : many of them are occupied by
the fat, which, however, as already explained, does not lie loose in the
areolar spaces, but is enclosed in its own vesicles. A small quantity of
colourless transparent fluid is also present in the areolar tissue, but, in
health, not more than is sufficient to moisten it. This fluid is generally
said to be of the nature of serum ; but it is not improbable that, unless
when unduly increased in quantity or altered in nature by disease, it may
resemble more the liquor sanguinis, as is the case with the fluid of most of
the serous membranes.
On comparing the areolar tissue of different parts, it is observed in some
to be more loose and open in texture, in others more dense and close,
according as free movement or firm connection between parts is to be pro-
vided for. In some situations, too, the laminae are more numerous ; in
AREOLAR TISSUE.
Ixxi
others the filamentous structure predominates, or even prevails exclusively ;
but it does not seem necessary to designate these varieties by particular
names, as is sometimes done.
When examined under the microscope, the areolar tissue is seen to be
principally made up of exceedingly fine, transparent, and apparently homo-
geneous filaments, from about 3"^^th to -2^00*- ^ an i Qcn i Q thickness,
or even less (fig. xxxv.). These are seldom single, being mostly united by
means of a small and usually imperceptible quantity of a homogeneous con-
necting substance into bundles and filamentous laminae of various sizes, which
to the naked eye, appear as simple threads and films. Though the bundles
may intersect in every direction, the filaments of the same bundle run nearly
parallel to each other, and no one filament is ever seen to divide into
branches or to unite with another. The associated filaments take an alter-
nate bending or waving course as they proceed along the bundle, but still
maintain their general parallelism. This wavy aspect, which is very charac-
teristic of these filaments, disappears on stretching the bundle, but returns
again when it is relaxed.
The filaments just described, though transparent when seen with trans-
mitted light under the microscope, have a white colour when collected in
considerable quantity and seen with reflected light ; and they not only occur
in the areolar tissue strictly so called, but form the chief part of the tendons,
ligaments, and other white fibrous connective tissues. They were long sup-
posed to be the only fibrous constituent existing in the areolar tissue, but it
has been shown (chiefly through the inquiries of Eulenberg, Henle, and
Bowman) that fibres of
Fig. XXXV.
another kind are inter-
mixed with them ; these
agree in all characters
and are obviously iden-
tical with the fibres of
the yellow elastic tis-
sue, and have accord-
ingly been named the
yellow or elastic fibres,
to distinguish them from
the white or waved
filaments above descri-
bed. They were at
one time termed nuclear
fibres (Kernfasern), on
account of their sup-
posed origin from nu-
clei ; but as it now ap-
pears that they have
no connection either
with nuclei or cells,
the latter appellation
must be abandoned.
Moreover, they differ
in chemical nature from
cells and nuclei, in as much as they resist the action of boiling alkaline
solutions of potash and soda, of moderate strength, which very speedily
destroy the cells and nuclei.
Fig. XXXV. FILAMENTS OP AREOLAR TISSUE, IN LARGER
AND SMALLER BUNDLES, AS SEEN UNDER A MAGNIFYING
POWER OP 400 DIAMETERS.
Two or three corpuscles are represented among them.
Ixxii
AREOLAR TISSUE.
In certain portions of the areolar tissue, as for instance in that which lies
under the serous and mucous membranes of particular regions, the yellow or
elastic fibres are abundant and large, so that they cannot well be overlooked ;
but in other parts they are few in number, and small, and are then in a
great measure hidden by
Fig. XXXVI. the white filaments ; in
such cases, however, they
can always be rendered con-
spicuous under the micro-
scope by means of acetic
acid, which causes the white
filaments to swell up and
become indistinct, whilst
the elastic fibres, not being
affected by that re- agent,
come then more clearly into
view (fig. xxxvi.). Under
the microscope the elastic
fibres appeartransparentand
colourless, \\ith a strong,
well-defined, dark outline.
They are, moreover, remark-
able for their tendency to
curl up, especially at their
broken ends, which gives
them a very peculiar aspect ;
and in many parts of the
areolar tissue they divide
into branches and join or
anastomose with one another, in the same n.anner, as in the pure elastic
tissue (a). They differ among themselves very widely in size, some being
as fine as the white filaments, others many times larger.
In the immature areolar tissue of the foetus there is a considerable amount
of soft jelly-like matter, of muco-albuminons nature, in the interstices of
the formed elements. This amorphous substance is for the most part incon-
spicuous in the perfected tissue, but exists abundantly in the umbilical cord,
where it forms the well-known Whartonian jelly ; it may also be seen, at all
periods, but in smaller quantity, in the areolar tissue within the vertebral
canal.
A very different view of the structure of areolar tissue from that here
stated was taken by Reichert, and adopted by Virchow, Donders, and other
distinguished histologists. According to tbis view the apparent bundles
consist of a substance in reality amorphous or homogeneous, aud its seeming
fibrillation is partly artificial, the result of cleavage, and partly an optical
illusion, arising from creasing or folding. In point of fact, however, the
bundles readily separate into fibrils after exposure to dilute solutions of
chromic acid, or to lime-water, or to baryta- water, by which the uniting
matter is dissolved ; so that there can be no doubt of their truly fibrillar
structure. At the same time it is not denied that immature fasciculi may
probably occur, in which the fibrillation is incomplete. Moreover, a homo-
geneous substance, not to be confounded with the soft jelly-like matter
previously noticed, but of firm consistence and agreeing in chemical nature
with the fibrils, envelopes the fasciculi in some situations in form of a fine
Fig. XXXVI. MAGNIFIED VIEW OP AREOLAR TISSUE
(FROM DIFFERENT PARTS) TREATED WITH ACETIC
ACID.
The white filaments are no longer seen, and the
yellow or elastic fibres with the nuclei come into view.
At c, elastic fibres wind round a bundle of white fibres,
which by the effect of the acid is swollen out between
the turns.
AREOLAR, TISSUE. Ixxiii
sheath (Kolliker) ; and it will be afterwards noticed as constituting a special
form or variety of connective tissue occurring elsewhere.
The elastic fibres lie, for the most part, without order, among the bundles of white
filaments ; but here and there we see an elastic fibre winding round one of these
bundles, and encircling it with several spiral turns. When acetic acid is applied, the
fasciculus swells out between the constricting turns of the winding fibre, and presents
a highly characteristic appearance (c). This remarkable disposition of the elastic
fibres, which was pointed out by Henle, is not uncommon in certain parts of the
areolar tissue ; it may be always seen in that which accompanies the arteries at the
base of the brain. It must be observed, however, that the encircling fibre sometimes
forms not a continuous spiral, but several separate rings ; moreover, the whole
appearance is explained by some histologists on the supposition that the bundles in
question are naturally invested with a delicate sheath, which, like the elastic tissue,
resists acetic acid, but, on the swelling up of the bundle under the operation of that
agent, is rent into shreds or segments, mostly annular or spiral, which cause the con-
strictions. Kolliker, who admits that some fasciculi have a sheath, yet supposes that
in these, as well as in naked bundles, the encircling fibres are produced by prolonga-
tions from the corpuscles (to be immediately noticed), uniting in form of a thread, or
of a network wrapped round the bundle.
Bodies, mostly with nuclei, and of the nature of cells, although not
shown to possess a distinct cell- wall, are found in the areolar tissue. These
are the connective-tissue-corpuscles. Some lie in the meshes of the tissue,
others are included within the fasciculi. The former are of no very regular
shape, rounded or oval (as in fig. xxxiv.), or, as described in the frog by
Ktihue, having a stellate or jagged outline with processes or offsets of
unequal size and length, here and there connected with processes from
neighbouring corpuscles in short, misshapen little masses of protoplasm,
but containing usually a well-formed oval nucleus and conspicuous nucleolua.
Those within the fasciculi are fusiform, with pointed ends, and lie length-
wise in the direction of the fasciculus (as shown, though imperfectly, in
tig. xxxvi. c.).
These bodies were imagined to be hollow, and it was conceived that, by the inter-
communication of their supposed tubular offsets they formed a system of reticulating
canals destined to distribute nutritive fluid to the connective tissue and other parts
into which that tissue enters. But, though soft, they are evidently solid objects ; and
though they probably effect some chemical change, or exert some other influence on
the interstitial nutritive plasma, or in some other way minister to nutrition, it is
clearly not as a system of channels for the conveyance of fluid. In the frog they
exhibit slow but distinct movements and changes of shape, like the pale blood-cor-
puscles ; and they may be regarded as cells retaining their primitive protoplasmic
condition, and subservient not only to the nutrition, but to the extension and repair
of tissues. There'can be little doubt, moreover, that they are largely concerned in
pathological and degenerative, as well as in reparative processes.
The areolar tissue contains a considerable quantity of water, and conse-
quently loses much of its weight by drying. It is almost wholly resolved
into gelatine by boiling in water. Acetic acid causes ifc, that is, the bundles
of white fibrils, to swell up into a soft, transparent, jelly-like mass.
Numerous blood-vessels are seen in the areolar tissue after a minute
injection. These for the most part only pass through it on their way to
other more vascular textures, but a few seem to end in capillaries destined
for the tissue itself, and dense clusters of vessels are distributed to the fat-
lobules. Large lymphatic vessels proceeding to distant parts also pass along
this texture, and abundant lymphatic networks may be discovered in many
parts of the subcutaneous, subserous, and subniucous areolar tissue, having
Ixxiv FIBROUS TISSUE.
evident relation to the function of the membranes under which they lie.
Absorption readily takes place from the interstices of the texture, but that
process may be effected through the agency of blood-vessels as well as of
lymphatics.
Larger and smaller branches of nerves also traverse this tissue on their
way to other parts ; but it has not been shown that any remain in it, and
accordingly it may be cut in a living animal apparently without giving pain,
except when the instrument meets with any of these traversing branches.
It is not improbable, however, that nerves end in those parts of the areolar
tissue, which, like that of the scrotum, contain contractile fibres ; but, if
present in such cases, the nerves, like the vessels of the fat, are, after all,
destined not to the areolar tissue but to another mixed with it.
The physical properties of this texture have been sufficiently indicated in
the foregoing description ; also its want of sensibility. The vital contrac-
tility ascribed to certain portions of it is most probably due to the presence
of muscular tissue.
With the exception of the epithelium, no tissue is so readily regenerated
as the areolar. It is formed in the healing of wounds and in the adhesion
of inflamed surfaces. It is produced also in many morbid growths.
FIBROUS TISSUE.
This substance is one of those which are serviceable in the body chiefly on
account of their mechanical properties, being employed to connect together
or to support and protect other parts. It is met with in the form of liga-
ments, connecting the bones together at the joints ; it forms the tendons of
muscles, into which their fleshy fibres are inserted, and which serve to attach
these fibres to the bones. In its investing and protecting character it
assumes the membranous form, and constitutes a class of membranes termed
"fibrous." Examples of these are seen in the periosteum and perichon-
drium which cover the bones and cartilages, in the dura mater which lines
the skull and protects the brain, and the fibrous layer which strengthens
the pericardium, also in the albugineous coat of the testicle, and the
sclerotic coat of the eye, which inclose the tender internal parts of these
organs. Fibrous membranes, named " aponeuroses " or " fascia;," are also
employed to envelope and bind down the muscles of different regions, of
which the great fascia inclosing the muscles of the thigh and leg is a well-
known example. The tendons of muscles, too, may assume the expanded
form of aponeuroses, as those of the broad muscles of the abdomen, which
form strong fibrous layers in the walls of that cavity and add to their
strength. It thus appears that the fibrous tissue presents itself under two
principal forms, the fascicular and the membranous.
Physical Properties. The fibrous tissue is white or yellowish white, with
a shining, silvery, or nacreous aspect. It is exceedingly strong and tough,
yet peiiectly pliant ; but it is almost devoid of extensibility. By these
qualities it is admirably suited to the purposes to which it is applied in the
animal frame. By its inextensible character it maintains in apposition the
parts which it connects against any severing force short of that sufficient to
cause actual rupture, and this is resisted by its great strength, whilst its
flexibility permits of easy motion. Accordingly the ligaments and tendons
do not sensibly yield to extension in the strongest muscular efforts ; and
though they sometimes snap asunder, it is well known that bones will break
more readily than tendons of equal thickness. The fibrous membranes are
proportionally strong and alike inextensible ; they will gradually yield, it is
FIBROUS TISSUE. Ixxv
true, when the extending force acts slowly and for a long time, as when
tumours or fluids slowly gather beneath them ; but perhaps this gradual
extension is accompanied with some nutritive change affecting the properties
of the tissue.
Structure. The fibrous tissue id made up of fine filaments, agreeing in all
respects with the white filaments of the areolar tissue already described.
Like these they are collected into bundles, in which they run parallel and
exhibit the same wavy character, cohering very intimately. The bundles
appear to the naked eye as fine shiaing threads or narrow flattened bands
for they vary greatly in thickness. They either run all in one direction as
in long tendons, or intersect each other in different planes as in some
aponeuroses, or they take various directions and decussate irregularly with
each other as in the dura mater. And when they run parallel to each other,
as in tendon, they do not keep separate throughout their length, but send
off slips to join neighbouring bundles and receive the like in turn ; so that
successive cross sections of a tendon or ligament present different figures
of the sectional areas of the bundles. A sheath of dense areolar tissue
covers the tendons and ligaments on the outside, and a variable amount of
the same tissue lies between the larger fasciculi ; little in tendons, more in
some fibrous membranes.
The filaments swell up and become indistinct when acted on by acetic
acid, like those of areolar tissue, and here also the acid discloses the exis-
tence of corpuscles and of elastic fibres, intermixed in small proportion with
the rest of the tissue. The elastic fibres are fine and generally branched
and connected together. The corpuscles, which have no real connection
with the elastic fibres, are for the most part lodged where the angles of the
fasciculi (which are usually prismatic in form) meet. They are fusiform or
lanceolate in figure, pointed at the ends, and lie lengthwise among the
bundles. In cross sections there is an appearance of radiating pointed pro-
cesses, diverging from the spots where the corpuscles are situated, and these
have been taken for branches or offsets extending laterally from these bodies;
but it seems to be satisfactorily shown that the apparent branches are
merely the crevices between the fasciculi, diverging from the poiut where their
angles meet. But although these fissures do not contain branches radiating
from the corpuscles, flat membraneous shreds can here and there be extracted
from them, which are by some supposed to be part of a membrane by which
each several bundle is ensheathed and separated from its neighbours.
The surface of a tendon or of any other part consisting of this texture,
appears marked across the direction of the fasciculi with alternate light and
dark streaks, which give it a peculiar aspect, not unlike that of a watered
ribbon. This appearance is owing to the wavy course of the filaments, for
when the light falls on them their bondings naturally give rise to alternate
lights and shadows.
The fibrous and areolar tissues thus agreeing in their ultimate structure,
it is not to be wondered at that sometimes the limits between the two should
be but ill-defined, and that the one should pass by inconspicuous gradations
into the other. Instances of such a transition may be seen in many of the
fasciae : these at certain parts consist of dense areolar tissue, but on being
traced farther are seen gradually to take on the fibrous character ; and
fascise, which in one body consist of areolar tissue, may be decidedly fibrous
in another.
In chemical constitution also the fibrous tissue is similar to the areolar.
It contains about two-thirds of its weight of water ; it becomes transparent,
ELASTIC TISSUE.
hard, and brittle, when dried, but readily imbibes water again and regains
its original properties. It is resolved into gelatin by boiling.
The fibrous tissue receives blood-vessels, but in general they are inconsi-
derable both in number and size compared with the mass of tissue to which
they belong. In tendons and ligaments with longitudinal fasciculi, the
chief branches of the vessels run parallel with and between the larger fasci-
culi, and, sending communicating branches across them, eventually form a
very open network with large oblong meshes. Some fibrous membranes, as
the periosteum and dura mater, are much more vascular ; but the vessels
seen in these membranes do not strictly belong to them, being destined for
the bones which they cover. The lymphatics of fibrous tissue are not suffi-
ciently known to be spoken of with certainty.
As to nerves, their general existence in this texture has not been satis-
factorily demonstrated by anatomical investigation. Recent iuquiries into
this subject have shown that the smaller tendons contain no nerves, and the
larger only such nervous filaments as accompany and belong to the vessels ;
and the same is true of the ligaments. The fasciae and the sheaths of ten-
dons are also destitute of nerves. On the other hand, fine nerves have been
traced in the interosseous membrane of the leg, and nervous filaments are
even abundant in the periosteum, but the majority of them do not belong
to the membrane itself, but are destined for the subjacent bone. Nerves
have also been traced in the dura mater ; some accompany the vessels,
others appear destined for the membrane itself, and others again for the
bones.
It has been proved by numerous observations and experiments, that the
tendons, ligaments, and other structures composed of fibrous tissue, are, in
the healthy state, quite insensible ; but then it is known, on the other hand,
that they occasion severe pain when inflamed, which cannot well be
accounted for on the supposition that they are entirely destitute of nerves.
Bichat, while he admitted their insensibility to cutting, burning, and most
other kinds of stimuli which cause pain in sensible textures, ascribed to
them a peculiar sensibility to twisting or to violent extension, and this
opinion has been supported by other authorities of weight, but the proofs
of it are not clear.
Fibrous tissue readily heals and unites when divided, as is seen in cases
of broken tendo Achillis. It is very generally produced as a uniting
medium of broken bones when osseous union fails to take place ; and is com-
mon as a diseased production in various kinds of tumours.
YELLOW OR ELASTIC TISSUE.
Whilst the fibrous tissue is remarkable for its want of extensibility, and
owes its usefulness as a constituent of the frame in a great measure to that
character, the substance we have now to consider possesses this property in
a very high degree, and is employed wherever an extensible and highly
elastic material is required in the animal structure.
Examples of this texture on a large scale are seen in the horse, ox,
elephant, and other large quadrupeds, in which it forms the great elastic
ligament, called ligamentum nuchce, that extends from the spines of the
vertebra to the occiput, and aids in sustaining the head ; in the same
animals it also forms an elastic subcutaneous fascia, which is spread over the
muscles of the abdomen and assists in supporting the contents of that
cavity. In the human body it is met with chiefly in the following situa-
tions, viz. :
ELASTIC TISSUE.
Ixxvii
1. Forming the ligamenta subftava, which extend between the arches of adjacent
vertebrae ; these ligaments, while they permit the bones to be drawn apart in flexion
of the body, aid in restoring and maintaining their habitual approximation in the
erect posture so far, therefore, relieving the constant effort of the erector muscles.
2. Constituting the chief part of the stylohyoid, thyrohyoid, and cricothyroid liga-
ments, and those named the vocal cords. Also extending, in form of longitudinal
bands, underneath the mucous membrane of the windpipe and its ramifications.
3. Entering, along with other textures, into the formation of the coats of the blood-
vessels, especially the arteries, and conferring elasticity on these tube?". 4. Beneath
the mucous membrane of the gullet and lower part of the rectum, also in the tissue
which surrounds the muscular coat of the gullet externally. 5. In the tissue which
lies under the serous membranes in certain parts. 6. In many of the fasciae, where
it is mixed with much areolar tissue. 7. Largely in the suspensory ligament and
subcutaneous tissue of the penis. 8. In considerable quantity in the tissue of the
skin.
The elastic tissue in its purest and moat typical condition, such as is seen
in the ligamentum nuchse of quadrupeds and the ligamenta subflava of the
human spine, has a yellow colour more or less decided ; it is extensible and
elastic in the highest degree, but is not so strong as ordinary fibrous liga-
ment, and it breaks across the direction of its fibres when forcibly stretched.
Its fibres may be easily torn separate in a longitudinal direction ; they are
often gathered into irregular fasciculi which run side by side but 'join at
short distances by slips with one another, and are further connected by
areolar tissue, which is always intermixed with them in greater or less
quantity. Elastic ligaments are also covered outwardly with a sheath of
areolar tissue.
When the elastic fibres are mixed up with a large proportion of some
other kind of tissue, their yellow colour may not appear, but they can
always be recognised by their microscopic
characters. When viewed under a tolerably Fig. XXXVII.
high magnifying power, they appear quite
transparent, with a remarkably well-
defined dark outline (fig. XXXVIL). They
run side by side, following a somewhat
bending course, but with bold and wide
curves, unlike the undulations of the white
connective filaments. As they proceed they
divide into branches, and join or anas-
tomose together in a reticular manner.
Elastic networks may be composed of fine
fibres with wide meshes, and this is the
character of all at first ; but while some
continue in this state, in others the elastic
fibres grow larger and broader and the
intervening spaces narrower, so that the
tissue may acquire a lamellar character
and present the appearance of a homo-
geneous membrane, which may be either
entire, or with gaps or perforations at short
intervals, in which case it constitutes the
fenestrated membrane of Henle, found in
the coats of the blood-vessels. A re-
markable character which elastic fibres exhibit in many specimens, is
their singular tendency to curl up at their broken ends ; and these
Fig. XXXVII. ELASTIC FIBRES
FROM THE LIGAMENTA SUBFLAVA,
MAGNIFIED ABOUT 200 DIAMETERS.
SPECIAL VARIETIES OF
ends are not pointed, but abruptly broken across. Their size is very
various ; the largest in man are nearly ^oV^th of an inch in diameter, the
smallest perhaps not more than -3-^0 o tn - In some varieties of tne tissue the
larger sized fibres prevail ; this is the case with the ligamenta subflava,
where their general diameter is about -y^o o th of an incl1 5 in otaer instances,
as in the chord so vocales, they are exceedingly fine. In some animals elastic
fibres are met with fj-^^i^ of an inch in thickness. Acetic acid produces
no change on the elastic fibres, while it speedily alters the wavy areolar
fibres that are usually intermixed with them in greater or less number.
They also withstand boiling for a short time in solutions containing ten to
fifteen per cent, of caustic potash or soda, by which the white fibres and
the corpuscles of connective tissue are speedily destroyed.
The elastic tissue, of course, contains water, and loses much of its weight
by drying ; but the proportion is said not to be so great as in most other
soft tissues. By very long boiling it yields a substance in some points
resembling gelatin, while a portion, equal to rather more than the half,
remains undissolved.
The gelatin, no doubt, comes from the intermixed areolar tissue ; but the dis-
solved matter is not pure gelatin, for it is precipitated by acetic acid, and by some
other reagents which do not disturb a solution of pure gelatin. The nature of the
substance which remains undissolved has not been determined. Caustic potash and
soda have little effect on elastic tissue in the cold, and in weak solutions even when
hot, unless the application is long continued ; boiling in concentrated solutions
speedily dissolves it. It is soluble with the aid of heat in dilute hydrochloric
acid.
Little is known respecting the blood-vessels and nerves of this texture.
The yellow ligaments, wliich contain it in its purest form, are but scantily
supplied with vessels ; and no nerves have been traced into them. I am
not aware of any experiments or observations as to their sensibility, but
there is no reason for supposing it to be greater than that of ordinary liga-
ments ; nor has it been shown that structures containing this tissue possess
vital contractility, unless they also contain contractile fibres of another
kind.
SPECIAL VARIETIES OF CONNECTIVE TISSUE.
1. Jelly-like connective tissue or mucous tissue. In the early embryo the
areolar tissue consists of a pellucid jelly and nucleated corpuscles. The soft
watery jelly contains the chemical principle of mucus, or rnucm, and, in
much less proportion, albumen, but no gelatin. In the general course of
development of the tissue, fibres, both white and elastic, are formed in the
soft matrix, and finally this substance entirely or in a great measure dis-
appears. But in certain cases the course is different. The cells may dis-
appear, only the jelly remaining, as in the vitreous humour of the eye; or
the corpuscles may branch out and join together in form of a network in
the jelly, with the persisting nuclei at the spot whence the threads
diverge. Such a condition is seen in the enamel-organ of growing teeth.
The areolar tissue surrounding and imbedding the vessels in the umbilical
cord consists of fusiform and ramified corpuscles associated with white
fibrillar bundles and elastic fibres, along with much of the soft matrix,
which is persistent at the time of birth and constitutes the jelly of
Wharton.
COXXECTIYE TISSUE.
Ixxix
2. Retiform* connective tissue; Eeticular tissue, and Cytogcnous
(Kolliker) ; Adenoid tissue (His). In this case the matrix disappears ;
neither white nor elastic fibres are developed, but the ramified corpuscles
unite together into a reticular or fine trabecular structure (fig. xxxvm.) ;
either retaining their nuclei as at a, or losing them and then forming a fine
network of simple fibres without nuclei as at b.
That in both forms the tissue is constructed of ramified corpuscles is shown
by its withstanding boiling in water, whilst it readily dissolves in hot alkaline
solutions. This form of connective tissue enters into the construction of cer-
tain organs and textures, where it serves as a supporting framework to their
peculiar elements and their nourishing blood-vessels, and thus becomes a
"sustentaeular" tissue (Stutzywebe, Germ.). In this way it forms a trabecular
network within the lymphatic glands, containing the lymph or chyle cor-
puscles in its meshes (as
at c). So also it is found Fig. XXXVIII.
in the solitary and agmi-
nated follicular glands
of the intestine, the
tongue and tonsils ; in
the thymus gland ; in
the pulp and Malpighian
bodies of the spleen, and
in the tissue of the in-
testinal mucous mem-
brane at certain parts ;
ia all which situations
the meshes contain cor-
puscles of similar exter-
nal character with those
in the lymphatic glands.
But, although thus relat-
ed to glands and thence
named "adenoid "tissue,
it exists also as a sus-
taining structure in
the brain and spinal cord, where, with finer branches and closer meshes, it
forms an extremely delicate framework supporting the proper nervous
substance, and has been called the retiodum (Kolliker).
3. Homogeneous connective tissue. More consistent than the mucous or
jelly-like tissue, and differing also in chemical nature, inasmuch as it
appears to be collagenous (i.e., yielding gelatin), and thus more nearly
related in substance to the white fibrillar tissue. It contains no fibres nor
fibrils, and may be quite transparent and uniform in character, or faintly
granular and striated. For the most part this substance occurs in the form
of homogeneous membranes ; examples of which are found in the external coat
of fine vessels, the hyaloid membrane in the eye, the capsules of the Mal-
pighian bodies in the kidney and spleen, the capsules of the solitary and
agminated intestinal glands and the lingual and tousillar follicular glands,
in the Graafian follicles, and in certain gland-ducts. It must be noted,
however, that some homogeneous membranes, as for example, the posterior
elastic lamina of the cornea, are of a different nature.
* I use the term "retiform," not because it signifies more or Jess than "reticular,"
but because the latter term is not unfrequently applied to areolar tissue.
Fig. XXXVIII. THIN SECTION FROM THE CORTICAL
PART OF A LYMPHATIC GLAND, MAGNIFIED.
A network of fine trabeculse formed by retiform or
adenoid tissue, from the meshes of which the lymph-cor-
puscles have been washed out, except at c, where they are
left (after His, slightly altered).
Ixxx CARTILAGE.
DEVELOPMENT OF CONNECTIVE TISSUE.
In those parts of the embryo where connective tissue is to be developed, there is at
first a deposit of nucleated corpuscles, having the characters common to the cells of
which the early embryo-body throughout consists. Between the cells is a small
amount of soft amorphous intercellular substance, which increases in quantity. This
is at first of a muco-albuminous nature, but is in great part changed into a gela-
tinous substance, which assumes a fibrillar character, and becomes converted into the
bundles of white wavy filaments that constitute the chief part of the areolar and
fibrous tissues. These bundles, after their first appearance, increase in size, and con-
tinue to grow larger after birth. Amongst these white fasciculi, elastic fibres, in
varying proportion, appear at a somewhat later period. These are also produced
from the intercellular substance, which in this case undergoes a different chemical
change. They appear from the first in form of networks pervading the intercellular
mass throughout, and not as single shorter fibres gradually lengthening out and joining
together ; nor do they appear to be formed by the linear coalescence of granules, but by
immediate differentiation in the intercellular substance. The elastic fibres are at
first exceedingly fine, but acquire greater thickness as development advances, and in
some situations what was originally a network may become an elastic membrane.
The cells in part remain as the connective-tissue-corpuscles already described; irre-
gularly ramified in open areolar tissue, but fusiform within the bundles and in the
interstices of dense fibrous tissue ; part of them become filled with fat, and form the
adipose tissue. The intercellular substance is usually reduced to an inconspicuous
amount, but in some situations remains in notable quantity.
Such is the most general course of development ; but, as will be understood from
what has preceded, it is different in particular cases. Thus, the intercellular sub-
stance may accumulate in large proportion, and the cells finally disappear, as in the
vitreous humour ; or the cells may be developed into retiform or cytogenous tissue,
without the formation of fibres, either white or elastic, in which case the jelly like
substance may remain, as in the enamel-organ; or the reticular interstices may become
filled with the elements of another tissue, as in the lymphatic glands and nervous
centres. In the development of the pure elastic ligaments the cells shrink as the
elastic fibres grow larger, and at length disappear altogether.
The intercellular substance may be excreted by the cells, but there is no clear
proof of this ; it may be an independent deposit between them ; and the disappearance
of the cells from pure elastic ligament would seem to show that, whatever be the
influence they exert in the original formation, they are not needed for carrying on
the nutrition, or even for the further growth of the tissue.
The foregoing account of the formation of connective tissue is derived from Kb'l-
liker's latest observations;* but Max Schultze considers that the intercellular sub-
stance, or matrix, is neither excreted by the cells, nor deposited ab extra, but is in
reality formed by conversion of part of the protoplasm which forms the bodies of the
cells (nucleated protoplasm-masses) : the matrix thus increases and becomes fibrillated
at the expense of the cells, which, now reduced to the nuclei surrounded with a small
portion of protoplasm, remain as the connective-tissue-corpuscles.
CARTILAGE.
This is the well-knowu substance commonly called " gristle." The follow-
ing are its more obvious characters. When in mass, it is opaque and of a
pearly or bluish white colour, in some varieties yellow ; but in thin slices ifc
is translucent. Although it can be easily cut with a sharp knife, it is
nevertheless of very firm consistence, but at the same time highly elastic,
so that it readily yields to pressure or torsion, and immediately recovers its
original shape when the constraining force is withdrawn. By reason of
* Neue Untersuchungen iiber die Entwickekmg des Bindegewebes. Wiirzb. naturwiss.
Zeitschr., vol. ii. Also Handbuch der Gewebelehre, 4th edit. 1863.
HYALINE CARTILAGE. Ixxxi
these mechanical properties, it is rather extensively used in the construction
of the body. Its specific gravity is 1 '15.
In the early embryo the skeleton is, in great part, cartilaginous ; but the
cartilage forming its different pieces, which have the outward form of the
future bones, in due time undergoes ossification or gives place to bone, in
the greater part of its extent at least, and hence this variety of cartilage is
named "temporary."
Of the permanent cartilages a great many are in immediate connection
with bone, and may be still said to form part of the skeleton. The chief
of these are the articular and the costal cartilages ; the former cover the
ends or surfaces of bones in the joints, and aflford these harder parts a thick
springy coating, which breaks the force of concussion and gives ease to their
motions ; the costal or rib-cartilages form a considerable part of the solid
framework of the thorax, and impart elasticity to its walls. Other perma-
nent cartilages enter into the formation of the external ear, the nose, the
eyelids, the Eustachiau tube, the larynx, and the windpipe. They strengthen
the substance of these parts without undue rigidity ; maintaining their
shape, keeping open the passages through them where such exist, and
giving attachment to moving muscles and connecting ligaments.
Cartilages, except those of the joints, are covered externally with a
fibrous membrane named the perichondrium.
When a very thin slice of cartilage is examined with the microscope, it is
seen to consist of nucleated cells, also named cartilage-corpuscles, dissemi-
nated in a solid mass or matrix. (Figs, xxxix., XL. } and XLI.)
The matrix is sometimes transparent, and to all appearance homogeneous ;
sometimes dim and very faintly granular, like ground glass : both these
conditions occur in hyaline cartilage, which may be regarded as the most
typical form of the tissue. Two varieties exist in which the matrix is per-
vaded to a greater or less extent by fibres. In the one named elastic or
yellow cartilage) the fibres are similar to those of elastic tissue ; in the
other, named jibro- cartilage, they are of the white kind as in ordinary
ligament.
HYALINE CARTILAGE.
lu hyaline cartilage the matrix, as just stated, is uniform and, in
the normal state, free from fibres. The cells consist of a rounded, oval, or
bluntly angular cell-body of translucent, but sometimes finely granular-
looking substance, with a clear round nucleus and one or more nucleoli.
The cell-body lies in a cavity of the matrix, which, in its natural condition,
it entirely fills. This cavity is bounded and inclosed by a transparent
capsule, which is seldom obvious to the eye, for it coheres intimately with
the surrounding matrix, with which it agrees in nature, and cannot usually
be distinguished without the aid of re-agents. The capsule has been
regarded as a secondary cell-wall and compared to the cellulose wall of
vegetable cells ; while the body which it contains is, on the same view, con-
sidered to be homologous with the primordial utricle and its contents. But
the same doubt prevails here as in the case of vegetables, as to the existence
of a proper membrane (the utricle) immediately investing the substance of the
cell. (See page xiv, and figures vm. and ix.)
In thin slices of young cartilage the capsules may be freed from the matrix by
means of concentrated mineral acids, and can then be shown as distinct vesicles
Ixxxii
HYALINE CARTILAGE.
having the cell-bodies within. The effect of acids is promoted by previous boiling
of the cartilage in water. By exposure to water and some other liquids the cell-
body shrinks away from the inside of the capsule, and assumes a jagged or other-
wise irregular figure, and then may hide the nucleus. It often contains larger or
smaller fat-globules.
The cells are rarely dispersed singly in the matrix ; they usually form
groups of different shapes and sizes. Towards the surface of the cartilage
the groups are generally flattened conformably with the surface (fig. XL.),
appearing narrow and almost linear when seen edgeways, as in a perpendi-
cular section. (Fig. xxxix., a.) The cells in a group have a straight out-
line where they adjoin or approach one another, but at the circumference of
the group their outline is rounded.
Such is the structure of hyaline cartilage in general, but it is more or less
modified in different situations.
Fig. XXXIX. Fig. XL.
V &
Fig. XXXIX. DIAGRAM REPRESENTING A VERTICAL SECTION OF ARTICULAR CARTILAGE,
SEEN WITH A LOW MAGNIFYING POWER.
a, Flattened groups of cells near the surface ; &, oblong groups, for the most part
directed vertically ; c, part of the bone.
Fig. XL. A THIN LAYER PEELED OFF FROM THE SURFACE OF THE CARTILAGE OF THE
HEAD OF THE HUMERUS, SHOWING FLATTENED GROUPS OF CELLS.
The shrunken cell-bodies are distinctly seen, but the limits of the capsular cavities
where they adjoin one another are but faintly indicated. Magnified 400 diameters.
In articular cartilage, the matrix in a thin section appears dim, like
ground glass, and has an almost granular aspect. The cells and nuclei are
small. The groups which they form are flattened at and near to the surface,
and lie parallel with it (fig. xxxix., a, and fig. XL.) ; deeper and nearer
the bone, on the other hand, they are narrow and oblong, like short strings
of beads, and are mostly directed vertically. (Fig. xxxix., 6, fig. XL.) It
is well known that articular cartilages readily break in a direction per-
pendicular to their surface, and the surface of the fraolure appears to the
naked eye to be striated in the same direction, as if they had a columnar
structure ; this has been ascribed to the vertical arrangement of the
rows of cells, or to a latent fibrous or columnar disposition of the sub-
stance of the matrix (Leidy). It was formerly held that the free
surface of articular cartilage is* covered with epithelium continued
HYALINE CARTILAGE.
Ixxxiii
from that of the synovial membrane, a thin stratum of areolar tissue
being interposed ; but the existence of such a covering is certainly not
general, at least in the
adult. It is easy, no p-^ XLI.
doubt, to peel off a thin
film from the surface of
the cartilage of the head
of the humerus or femur ;
but this superficial layer
is really part of the car-
tilage, and its broad
patches of cells with the
intermediate matrix are
not to be mistaken. (See
fig. XL.) At the same
time, it is true that near
the margin of these car-
tilages a layer of fine
filamentous tissue, co-
vered with epithelium,
is prolonged a certain
way over their surface
from the synovial mem-
brane. The matrix of
articular cartilage rarely,
or perhaps never, be-
comes pervaded by
fibres like those so often
seen in rib-cartilage, nor
is it prone to ossify.
In the cartilages of the ribs, the corpuscles or cells, which are of large size,
are also collected in groups. Near the exterior of the cartilage they are
flattened, and lie parallel with the surface, forming a superficial stratum
from i-jy to 3 n of an inch thick. As to those situated more inwardly, we
can sometimes observe, in a transverse slice, that they form oblong groups
disposed in lines radiating to the circumference ; but this arrangement is
not constant, and they often appear quite irregular. The cells, with the
exception of those lying upon the surface, commonly contain larger or
smaller drops of oil ; and the nucleus, being generally undiscoverable, is
concealed by the fat or may itself have undergone a fatty metamorphosis.
The matrix is tolerably clear, except where fibres have been developed in it,
in which parts it is opaque and yellowish. Such fibrous patches are very
frequent ; the fibres are fine, straight, and parallel, appearing transparent
when few together ; they withstand the action of acetic acid. It is not un-
common to find the rib-cartilages extensively ossified.
It was observed by Herissant * that the costal cartilages, after many
months' maceration in putrid water, would sometimes break up into thin
plates, directed across the axis of the cartilage ; from which he inferred
that these cartilages were naturally made up of such transverse lamellae :
but the point does not appear to have been further investigated.
The description given of the microscopic characters of the costal cartilages
will apply with little variation to the ensiform cartilage of the sternum, to
* Mem. de 1'Acad. des Sc. de Paris, 1748.
Fig. XLI. VKRTIOAL SECTION OP ARTICULAR CARTILAGE
OF TUB HEAD OP THE HUMERUS.
A deep portion near the bone. Magnified 400 dia
meters. Each cell-cavity contains a mass shaped like
itself, the shrunken cell- body, in the midst of which a
round nucleus is probably concealed.
Ixxxiv HYALINE CARTILAGE.
the cartilages of the larynx and windpipe, except the epiglottis and corni-
cula laryngis, and to the cartilages of the nose. With the exception of the
last, these resemble the rib-cartilages also in their tendency to ossify.
The characters of the temporary cartilages, which are hyaline, will be
given in the account of the formation of bone.
No nerves have been traced into any of the cartilages, and they are known
to be destitute of sensibility.
In the healthy state, 110 blood-vessels penetrate the articular cartilages.
Whatever nutrient fluid they require seems to be derived from the vessels of
adjoining textures, especially the bone, and to be conveyed through the
tissue by imbibition. In the embryo, a layer of vessels is prolonged some
way over the surface, underneath the sy no vial membrane ; but, as deve-
lopment proceeds, these subsynovial vessels retire towards the circumference
of the cartilage, and eventually form a narrow vascular border round it,
which has been named the circulus articuli vasculosus.
When the tissue exists in thicker masses, as in the cartilages of the ribs,
canals are here and there excavated in its substance, along which vessels are
conducted to supply nourishment to the parts too distant to receive it from
the vessels of the perichondrium. But these canals are few and wide apart,
and the vessels do not pass beyond them to ramify in the intermediate
mass, which is accordingly quite extravascular. It must be further
remembered respecting these vascular canals, that many of them lead to
spots where the cartilage is undergoing ossification, and convey vessels to
supply the bony deposits.
Ordinary permanent hyaline cartilage contains about three-fifths of its
weight of water, and becomes transparent by drying. By boiling it iu
water for fifteen or twenty hours, it is resolved into chondrin. This is a
substance said to gelatinise on cooling, although it may be doubted whether
the congelation is not in reality owing to an admixture of gelatin derived
from fibrous tissue not duly separated from the cartilage. Like gelatine,
chondrin is thrown down from its solutions by taunic acid, alcohol, ether,
creasote, and corrosive sublimate, and not by prussiate of potash. It differs
from gelatin in being precipitated by the mineral and other acids, the
acetic not excepted ; also by alum, sulphate of alumina, persulphate of iron,
and acetate of lead ; the precipitates being soluble in an excess of the
respective precipitants. The temporary cartilages are resolved into a matter
which has the chemical reactions of chondrin, but does not gelatinise.
Cartilage affords by incineration a certain amount of mineral ingredients ;
3 '4 per cent, of ashes were obtained from costal cartilages by Frommherz
and Gugert, and 100 parts of these ashes were found to consist of
Carbonate of soda 35*07
Sulphate of soda ......... 24'24
Chloride of sodium . . . . . . . . 8'23
Phosphate of soda . . . . . . . . . 0'92
Sulphate of potash . . . . . . . .1-20
Carbonate of lime 18-37
Phosphate of lime . . . . . . . .4-06
Phosphate of magnesia ........ 6'91
Oxide of iron, and loss . . . . . . .1*00
Von Bibra found the amount of carbonates very small, and that of the
other salts very variable. Soda-salts greatly preponderate over those of
potash, which may even be absent altogether.
ELASTIC OR YELLOW CARTILAGE. Ixxxv
Development of hyaline cartilage. The parts of the embryo which are about to
become cartilages are made up at first of the common embryonic cells from which the
tissues generally originate. The cell-contents clear up, the nucleus becomes more
visible, and the cells, mostly of polygonal outline, appear surrounded by clear lines of
pellucid substance, forming as it were a network of bright meshes inclosing them,
but in reality consisting of the cohering capsules of the contiguous cells, and consti-
tuting all that exists of the matrix at this time. Amyloid matter appears at an
early period in the protoplasm of cartilage-cells. Rouget found it in the sheep's
embryo of two months, both in ossifying cartilage and in the cartilages of the
trachea. The subsequent changes consist in enlargement and multiplication of the
cells and development of the intermediate matrix. The cells multiply by division.
The process is described at page xvii, although all the successive steps there
described and represented in the figure (xn.) have not been actually traced. In
growing cartilage from the frog-larva, Heidenhain* observed a double (i.e. divided)
nucleus in some cells, and in certain of these a straight linear partition running
across the cell between the two nuclei. This partition was recognised to be double,
and doubtless formed by the contiguous thin capsules of two new cells formed by
division of the previously single one. It is doubtful how the capsule or secondary
cell-wall is produced ; whether excreted by the cell which it afterwards incloses, as
held by Kb'lliker, or formed by conversion of a superficial layer of the protoplasm of
the cell-body, as taught by Max Schultze, or a primarily independent deposit round
the cells. However this may be, there is at first no matrix but what is made up of
the simple capsules. In further growth there is a difference, according as the cells do
or do not undergo frequent division. In the latter case a cell becomes surrounded
by many concentric capsules formed in succession ; that is, the first capsule is ex-
panded, and the others formed each within its expanding predecessor, so that the
cartilage comes to consist of scattered cells, each with a concentric system of capsules,
which by means of re-agents may be rendered visible in the neighbourhood of the
cells, but further off are inseparably blended into an uniform substance. When, on the
other hand, the cells have a tendency to frequent subdivision, the new capsules are
produced by the new cells, and are included in and finally blend with those which
had belonged to the previous cells, as shown by fig. xn.
The matrix, although thus formed of the capsules, becomes to all appearance homo-
geneous ; but in sections of cartilage that have been exposed to acids and other re-
agents, the contour lines of the capsules round cells and cell-groups may be more
or less distinctly brought into view. But, whilst admitting that the capsules have a
share in the production of the matrix, Kb'lliker and some other histologists incline
to the opinion that part of it is an independent deposit. Heidenhain, however, has
found that, when thin sections of cartilage are digested for twenty-four hours in water,
at from 112 to 122 F., or in diluted nitric acid with chlorate of potash for a greater
or less time according to the degree of dilution, the matrix becomes parted or
marked off into polygonal areas corresponding to the larger groups of cells, and these
again into smaller groups, or single cells, without any intervening substance ; the
whole matrix thus appearing to be portioned out into segments, each appertaining to
a larger or smaller group of cells, and in all probability representing the aggregated
capsules belonging to them.
The vital changes which occur in cartilage take place very slowly. Its mode of
nutrition has been already referred to ; it is subject to absorption, and when a
portion is absorbed in disease or removed by the knife, it is not regenerated. Also,
when fractured, as sometimes happens with the rib-cartilages, there is no reunion by
cartilaginous matter, but the broken surfaces become connected, especially at their
circumference, by fibrous or dense areolar tissue, often by a bony clasp. But, not-
withstanding that normally it is not regenerated, hyaline cartilage occurs in perfectly
characteristic form as a morbid product in certain tumours.
ELASTIC OR YELLOW CARTILAGE.
The epiglottis and cornicula of the larynx, the cartilages of the ear and of
the Eustachian tube, differ so much from the foregoing, both in intimate
* Studien des Physiologischen Instituts zu Breslau, 2ter Heft, 1863.
FIBRO-CAETILAGE.
structure and outward characters, that they have been included in a
class apart, under the name of the "elastic," "yellow," or "spongy"
cartilages. These are opaque and somewhat yellow, are more flexible and
tough than the ordinary cartilages, and
have little tendency to ossify. They
Fig. XLII. are maf ] e U p O f ce iis and a matrix, but
the latter is everywhere pervaded with
fibres (fig. XLTI.), except sometimes in a
little area or narrow zone left round each
of the cells. These fibres resist the
action of acetic acid ; they are in most
parts short, straight, and confusedly
intersecting each other in all directions,
like the filaments in a piece of felt ; in
such parts the matrix has a rough in-
distinctly granular look. Here and there
the fibres are longer and more fascicu-
F!g. XLII. SECTION OP THE EPI- lated, but still interlace at short distances.
GLOTTIS, MAGNIFIED 380 DIAMETERS j n thin sections the cells readily drop
(Dr. Baly). out from the ma t r i x> leaving empty the
cavities which they occupied.
In the foetus the matrix of elastic cartilage is at first homogeneous and hyaline,
and the elastic fibres are then produced in it, quite independently of the cells, and in
the same way as in the intercellular substance of growing elastic ligaments.
FIBRO- C ARTILA GE.
This is a substance consisting of a mixture of the fibrous and cartilaginous
tissues, and so far partaking of the qualities of both. Like hyaline car-
tilage, it possesses firmness and elasticity, but these properties are united
with a much greater degree of flexibility and toughness. It presents itself
under various forms, which may be enumerated under the following heads.
1. Inter articular fibro-cartilages. These are interposed between the
moving surfaces of bones, or rather of articular cartilages, in several of the
joints. They serve to maintain the apposition of the opposed surfaces in
their various motions, to give ease to the gliding movement, and to
moderate the effects of great pressure. In the joint of the lower jaw and
in that of the clavicle they have the form of round or oval plates, growing
thinner towards their centre; in the knee-joint they are curved in form of a
sickle, and thinned away towards their concave free edge. In all cases
their surfaces are free, while they are fixed by synovial or fibrous membrane
at their circumference or extremities. The synovial membrane of the joint,
or at least its epithelial coat, is prolonged for a short distance upon these
fibro-cartilages, from their attached margin.
2. The articular cavities of bones are sometimes deepened and extended
by means of a rim or border of fibro- cartilage. A good example of one of
these circumferential or marginal fibro-cartilages is seen in the hip-joint,
attached round the lip of the cotyloid cavity.
3. Connecting fibro-cartilages are such as pass between the adjacent
surfaces of bones in joints which do not admit of gliding motion, as at the
symphysis of the pubes and between the bodies of the vertebrae. They
have the general form of disks, and are composed of concentric rings of
fibrous tissue with cartilage interposed ; the former predominating at the
BOXE. Ixxxvii
circumference, the latter increasing towards the centre. The bony surfaces
between which they pass are usually encrusted with true cartilage. The
modifications which they present in particular instances are described in the
special anatomy of the joints.
4, The bony grooves in which tendons of muscles glide are lined with a
thin layer of nbro-cartilage. Small nodules of this tissue (sesamoid fibro-
cartilages) may also be developed in the substance of tendons, of which
there is an example in the tendon of the tibialis posticus, where it passes
beneath the head of the astragalus. Lastly, nbro-cartilage is sometimes
connected with muscular tissue, and gives attachment to muscular fibres,
like that which is known to exist at the orifices of the heart.
Fibro-cartilage appears under the microscope to be made up of bundles of
fibres, like those of ordinary ligament, with cartilage-cells intermixed ; but
the proportion of the two elements differs much in the different instances
above enumerated. In general the fibrous tissue very greatly predominates,
and in some cases, as in the iuterarticular laminse of the knee-joint, ifc
constitutes almost the entire structure. In the intervertebral disks the
cartilage-corpuscles are abundant towards the centre of the mass where the
cartilaginous tissue prevails, and the substance is softer.
In chemical composition this texture agrees most with ligament, yielding
gelatin when boiled.
Its blood-vessels are very few, and, according to Mr. Toynbee,* are
confined to the parts that are fibrous. Its vital changes are slow ; it is
subject to absorption, but much less readily so than bone ; hence it is no
uncommon thing to find the intervertebral disks entire when the adjacent
bodies of the vertebrae have been destroyed by disease. It has not much
tendency to ossify.
Little is known concerning the mode of development of fibro- cartilage.
Mr. Toynbee concludes from his researches that the cartilaginous element is
relatively more abundant at early periods.
BONE, OR OSSEOUS TISSUE.
The bones are the principal organs of support, and the passive instruments
of locomotion. Connected together in the skeleton, they form a framework
of hard material, which affords attachment to the soft parts, maintains them
in their due position, and shelters such as are of delicate structure, giving
stability to the whole fabric, and preserving its shape ; and the different
pieces of the skeleton, being jointed moveably together, serve also as levers
for executing the movements of the body.
While substantially consisting of hard matter, bones in the living body
are covered with periosteum and filled with marrow ; they are also pervaded
by vessels for their nutrition.
External configuration. In their outward forms the bones present much
diversity, but have been reduced by anatomists to the following classes.
1. Long or cylindrical, such as the chief bones of the limbs. These consist
of a body or shaft, cylindrical or more frequently angular in shape, and two
ends or heads, as they are often called, which are usually much thicker than
the shaft. The heads, or ends, have smooth surfaces for articulation with
neighbouring bones. The shaft is hollow and filled with marrow, by which
* Phil. Trans. 1841.
Ixxxviii
sufficient magnitude and strength are attained without undue increase of
weight. 2. Tabular or flat bones, like the scapula, the ilium, the ribs, the
lower jaw, and the bones forming the roof and sides of the skull. Many of
these contribute to form the walls of cavities. 3. Short bones, often also
called round bones, though most of them rather are angular ; the wrist and
tarsus afford examples of these. 4. Irregular or mixed bones, which would,
perhaps, be better named " complex : " such as cannot be entirely referred
to any of the foregoing classes. These are mostly situated in the median
plane, and have a complex but symmetrical figure ; the vertebrae may be
taken as instances of them.
The surfaces of bones present various eminences, depressions, and other
marks ; and, to designate these in descriptive osteology, certain general
terms are employed, of which the following are those most commonly in use.
1. Eminences. To any prominent elevation jutting out from the surface
of a bone the term " process " or " apophysis" is applied. It often happens
that such a process is originally ossified separately from the rest of the bone,
and remains long unconnected with the main body (by osseous union at
least); in this condition it is named an "epiphysis." In many bones,
considerable portions at the extremities or most prominent parts are
originally ossified separately as epiphyses. This is the case with the
ends of the long bones, and in this instance the shaft is named the
" diaphysis."
Processes or apophyses are further designated according to their different
forms. A slender, sharp, or pointed eminence is named a " spine " or
" spinous process ; " a tubercle, on the other hand, is a blunt prominence ;
a " tuberosity " (tuber) is broader in proportion to its elevation, and has a
rough uneven surface. The term "crest" is usually applied to the
prominent border of a bone, or to an elevation running some way along its
surface ; but the latter is more commonly denominated a " line " or
"ridge." A "head" (caput, capitulum, or capitellum) is a rounded
process, supported on a narrower part named its neck (cervix). A " cori-
dyle " has been defined to be an eminence bearing a flattened articular
surface ; but this term has been very variously applied by anatomists both
ancient and modern.
2. Cavities and depressions of bones. An aperture or perforation in the
substance of a bone is named a " foramen," A passage or perforation often
runs for some way in the bone, and then it is termed a " canal " or
"meatus." On the other hand, it may assume the form of a "fissure,"
and is named accordingly. A "fossa" is an open excavation or depression
on the surface of a bone, or of a part of the skeleton formed by several
bones. A fossa may form part of a joint, and be adapted to receive the
prominent part of a neighbouring bone; it is then said to be "glenoid,"
when shallow ; but a deep excavation, of which the socket for the head of
the thigh-bone is an example, is named a " cotyloid" cavity. The meanings
of the terms "notch" (incisura), and "groove," or "furrow" (sulcus), are
sufficiently plain. " Sinus " and "antrum"are names applied to certain
large cavities situated within the bones of the head and opening into
the nose.
Physical properties of lone. Bone has a white colour, with a pink and
slightly bluish tint in the living body. Its hardness is well known, but it
also possesses a certain degree of toughness and elasticity ; the last pro-
perty is peculiarly well marked in the ribs. Its specific gravity is from 1'87
to 1-97.
BONE. Ixxxix
Chemical Composition. Bone consists of an earthy and an animal part,
intimately combined together ; the former gives hardness and rigidity, the
latter tenacity, to the osseous tissue.
The earthy part may be obtained separate by calcination. When bones
are burned in an open fire, they first become quite black, like a piece of
burnt wood, from the charring of their animal matter ; but if the fire be
continued with free access of air, this matter is entirely consumed, and they
are reduced to a white, brittle, chalk-like substance, still preserving their
original shape, but with the loss of about a third of their weight. The
earthy constituent, therefore, amounts to about t>vo-thirds of the weight of
the bone. It consists principally of phosphate of lime, with about a fifth
part of carbonate of lime, and much smaller proportions of fluoride of
calcium, chloride of sodium, and magnesian salts.
The animal constituent may be freed from the earthy, by steeping a bone
in diluted hydrochloric acul. By this process the salts of lime are dissolved
out, and a tough, flexible substance remain*, which, like the earthy part,
retains the perfect figure of the original bone in its minutest details ; so
that the two are evidently combined in the most intimate manner. The
animal part is often named the cartilage of bone, but improperly, for it
differs entirely from cartilage in structure, as well as in physical properties
and chemical nature. It h much softer and mujh more flexible, and by
boiling it is almost wholly resolved into gelatin. It may accordingly be
extracted from bones, in form of a jelly, by boiling them for a considerable
time, especially under high pressure.
The earthy or saline matter of bone, as already stated, constitutes about two-thirds
or 667 per cent., and the animal part one-third, or 33'3 per cent. ; but from observa-
tions made on animals, it appears that the proportion of the several constituents may
differ somewhat in different individuals of the same species under apparently similar
conditions. The proportion of earthy matter appears to increase for some time after
birth, and is considerably greater in adults than in infants ; but, from the varying
conditions of individuals as to health and nutrition in after life, there is as yet no
thoroughly comparable series of experiments to determine whether any constant
difference exists in old age. Moreover, it is not clearly established that the differ-
ences observed depend on the composition of the proper osseous substance ; for the
larger proportion of animal matter in infancy may be due to the greater vascularity
of infantile bones and the difficulty of thoroughly removing the vessels from their
pores. The spongy osseous tissue, carefully freed from fat and adhering membranous
matter, has been found to contain rather less earth than the compact substance : and
in accordance with this result, differences, although on the whole insignificant, have
been found in different bones of the skeleton, apparently depending on the relative
amount of their compact and spongy tissue. (Rees, Von Bibra, Alphonse Milne-
Edwards.) Here again it remains to be shown that the result is not due to differences
in the proportion of minute pores and lacunae, which contain soft matter scarcely
separable in such experiments.
Subjoined are the statements of two analyses. The one, by Berzelius, is well
known; the other, which nearly agrees with it, was performed by Mr. Middleton, in
the laboratory of University College.*
Berzelius. Middleton.
Animal matter 33 30 3343
Phosphate of lime 51-04 51'11
Carbonate of lime 11-30 10-31
Fluoride of calcium 2-001-99
Magnesia, wholly or partially in the state of phosphate . 1*16 1'67
Soda and chloride of sodium V20 1-68
* Philosophical Magazine, vol. xxv. p. 18.
xc BONE.
The phosphate of lime is peculiar, and passes in chemistry under the name of the
" bone-earth phosphate." It is a tribasic phosphate, consisting probably of 8 equiva-
lents of lime and 1 of water, with 3 eq. of phosphoric acid. Von Bibra and A. Milne-
Edwards * found the proportion of the carbonate of lime to the phosphate, greater in
spongy than in compact tissue, and less in infantile bones generally than in those of
adults. M.-Edwards considers that carbonate is formed from decomposition of the
basic phosphate by the carbonic acid of the blood, and that the proportion must
necessarily vary with the state of nutrition ; in infancy there is less decomposition
and also more rapid elimination of the products of decomposition, hence propor-
tionally less carbonate of lime. The fluoride of calcium is found in larger quantity
in fossil than in recent bones indeed, its presence in the latter was lately denied
altogether ; but since then, the original statements of Morichini and of Berzelius,
to the effect that it exists in recent as well as fossil bones, have been satisfactorily
confirmed.
Structure. On sawing up a bone, it will be seen that it is in some parts
dense and close in texture, appearing like ivory ; in others open aud
reticular : and anatomists accordingly distinguish two forms of osseous
tissue, viz., the compact, aud the spongy or cancellated. On closer ex-
amination, however, especially with the aid of a magnifying glass, it will be
found that the bony matter is everywhere porous in a greater or less degree,
and that the difference between the two varieties of tissue depends on the
different amount of solid matter compared with the size and number of the
open spaces in each ; the cavities being very small in the compact parts of
the bone, with much dense matter between them ; whilst in the cancellated
texture the spaces are large, and the intervening bony partitions thin and
slender. There is, accordingly, no abrupt limit between the two, they
pass into one another by degrees, the cavities of the compact tissue widening
out, and the reticulations of the cancellated becoming closer as they approach
the parts where the transition takes place.
In all bones, tlie part next the surface consists of compact substance,
which forms an outer shell or crust, whilst the spongy texture is contained
within. In a long bone, the large round ends are made up of spongy tissue,
with only a thin coating of compact substance ; in the hollow shaft, on the
other hand, the spongy texture is scanty, and the sides are chiefly formed
of compact bone, which increases in thickness from the extremities towards
the middle, at which point the girth of the bone is least, and the strain on it
greatest. In tabular bones, such as those of the skull, the compact tissue
forms two plates, or tables as they are called, inclosing between them the
spongy texture, which in such bones is usually named dip/oe. The short
bones, like the ends of the long, are spongy throughout, save at their sur-
face, where there is a thin crust of compact substance. In the complex or
mixed bone*, the two substances have the same general relation to each
other ; but the relative amount of each in different parts, as well as their
special arrangement in particular instances, is very various.
On close inspection, the cancellated texture is seen to be formed of slender
bars or spicula of bone and thin lamellae, which meet together and join
in a reticular manner, producing an open structure which has been com-
pared to lattice- work (cancelli), and hence the name usually applied to it.
In this way considerable strength is attained without undue weight, and it
may usually be observed that the strongest laminae run through the struc-
ture in those directions in which the bone has naturally to sustain the
greatest pressure. The open spaces or areolae of the bony network com-
* Ann. des Sc. Nat. 4me Serie, vol. xiii. 1860.
BONE.
municate freely together ; in the fresh state they contain marrow or blood-
vessels, and give support to these soft parts.
Fig. XLIII. A, TRANSVERSE SECTION OP A BOICE (ULNA) DEPRIVED OF ITS EARTH BY
AOID.
The openings of the Haversian canals seen. Natural size. A small portion is shaded
to indicate the part magnified in Fig. B.
B, PART OF THE SECTION A, MAGNIFIED 20 DIAMETERS.
The lines indicating the concentric lamellae are seen, and among them the corpuscles or
lacuiise appear as little dark specks.
The compact tissue is also full of holes ; these, which are very small, are
best seen by brtaking across the shaft of .a long bone near its middle, and
examining it with a common magnifying glass. Numerous little round
apertures (fig. XLIII. A) may then be seen on the broken surface, which are the
openings of short longitudinal passages running in the compact substance,
and named the Haversian canals, after Clopton Havers, an English physi-
cian and writer of the seventeenth century, who more especially called
attention to them. Blood-vessels run in these canals, and the widest of
them also contain marrow. They are from T ^ 5 th to ^^th ^ an " lcn * n
diameter : I have measured some which were no more than ^-^ g ^th, but
these are rare ; the medium size is about ^ Jo tn - The widest are those
nearest the medullary cavity, and they are much smaller towards the cir-
cumference of the bone. They are quite short, as may be seen in a longi-
tudinal section, and somewhat crooked or oblique at their ends, where they
xcii BONE.
freely open into one another, their oblique communications connecting them
both longitudinally and laterally. Those also which are next the circum-
ference of the bone, open by minute pores on its external surface, and the
innermost ones open widely into the medullary cavity ; so that these short
channels collectively form a sort of irregular network of tubes running
through the compact tissue, in which the vessels of that tissue are lodged,
and through the medium of which these vessels communicate together, not
only along the length of the bone, but from its surface to the interior,
through the thickness of the shaft. The canals of the compact tissue in
the other classes of bones have the same general characters, and for the
most part run parallel to the surface.
On viewing a thin transverse section of a long bone with a microscope
of moderate power, especially after the earthy part has been removed by
acid (fig. XLIII. B), the opening of each Haversian canal appears to be sur-
rounded by a series of concentric rings. This appearance is occasioned by
the transverse sections of concentric lamella which surround the canals.
The rings are not all complete, for here and there one may be seen ending
between two others. In some of the sets the rings are nearly circular, in
others oval, differences which seem mostly to depend on the direction in
which the canal happens to be cut : the aperture, too, may be in the centre,
or more or less to one side, and in the latter case the rings are usually
narrower and closer together on the side towards which the aperture deviates.
Again, some of the apertures are much lengthened or angular in shape, and
the lamellae surrounding them have a corresponding disposition. Besides
the lamellae surrounding the Haversian canals, there are others disposed
conformably with the circumference of the bone (fig. XLIII. B, a), and which
may therefore be said to be concentric with the medullary canal ; some of
these are near the surface of the bone, others run between the Haversian
sets, by which they are interrupted in many places. Lastly, in various
parts of the section, lines are seen which indicate lamellae, differing in
direction from both of the above-mentioned orders. As to the circum-
ferential laminae, Messrs. Tomes and De Morgan state that they are by no
means so common as is generally supposed ; further, that they are most
conspicuous in bones of full growth, in which, consequently, nutritive
changes proceed slowly ; and that their presence may be made the means of
determining, within certain limits, the age at which a bone has arrived.
These authors observe, that in young and rapidly growing bones the lamina)
are frequently seen to have an undulating direction, which they consider as
a sign that the tissue is undergoing rapid nutritive changes.
The appearance in a longitudinal section of the bone is in harmony with
the account above given : the sections of the lamellae are seen as straight
and parallel lines, running in the longitudinal direction of the bone, except
when the section happens to have passed directly or slantingly across a
canal ; for wherever this occurs there is seen, as in a transverse section, a
series of rings, generally oval and much lengthened on account of the obli-
quity of the section.
The cancellated texture has essentially the same lamellar structure. The
slender bony walls of its little cavities or areolse are made up of super-
imposed lamellae, like those of the Haversian canals (fig. XLIII. B, b) t only
they have fewer lamellae in proportion to the width of the cavities which
they surround ; and, indeed, the relative amount of solid matter and open
space constitutes, as already said, the only difference between the two forms
of bony tissue ; the intimate structure of the solid substance and the
BONE.
1C 111
manner of its disposition round the cavities being essentially the same in
both.
Besides the openings of Haversian canals as above described, a trans-
verse section of the compact bone now and then presents vacuities or spaces
formed by absorption of the tissue. These are named "Haversian spaces"
by Tomes and De Morgan, who first showed that they occur not only in
growing bone but at all periods of life. In their primitive condition these
cavities are characterised by an irregular or jagged outline, and their forma-
tion by absorption is further indicated by their encroaching on the adjacent
groups of concentric lamellae, which have been, as it were, eaten away to
a greater or less extent to give place to the new cavity. In another stage
the spaces in question are lined by new formed lamellae, which may as yet
be confined to the peripheral part of the vacuity, or may fill it up in a
concentric series, leaving a Haversian aperture in the middle, and in fact
constituting a system of concentric Haversian lamellae, interpolated or
intruded among those previously existing. The concentric lamellae, which
thus come to occupy a greater or less extent of the area of the cavity, are
of course bounded exteriorly by segments of adjoining Haversian lamella),
which have been more or less cut in upon in the excavation of the space.
It has been further observed by Tomes and De Morgan, that vacuities may
sometimes be seen which are being filled up at one part by the deposition
of lamellae, whilst they are extending themselves by absorption at another.
The Haversian spaces are most numerous in young and growing bones ; but,
as already stated, they occur also after growth is completed. Their origin
and changes will be better understood after the reader has perused the
Fig. XLIY.
Fig. XLIV. TRANSVERSE SECTION OP COMPACT TISSUE (OP HUMERDS) MAGNIFIED ABPUT
150 DIAMETERS.
Three of the Haversian canals are seen, with their concentric rings ; also the corpuscles
or lacunas, with the canaliculi extending from them across the direction of the lamellae.
The Haversian apertures had become filled with debris in grinding down the section, and
therefore appear black in the figure, which represents the object as viewed with trans-
mitted light.
xciv BONE.
account of the growth and development of bone, to which head, indeed, the
subject more properly belongs, although it has seemed expedient to intro-
duce it here.
All over the section numerous little dark specks are seen among the
lamelhe. These are named the " osseous corpuscles;" but as it is now
known that they are in reality minute cavities existing in the bony sub-
stance, the name of u lacunae " has since been more fittingly applied to
them. To see the lacuuse properly, however, sections of unsoftened bones
must be prepared and ground very thin, and a magnifying power of from
200 to 300 must be employed. Such a section, viewed with transmitted
light, has the appearance represented in fig. XLIV. The openings of the
Haversian canals are seen with their encircling lamellae, and among these
the corpuscles or lacuuse, which are mostly ranged in a corresponding
order, appear as black or dark brown and nearly opaque, oblong spots, with
fine dark lines extending from them and causing them to look not unlike
little black insects ; but when the same section is seen against a dark
ground, with the light falling on it (as we usually view an opaque object),
the little bodies and lines appear quite white, like figures drawn with
chalk on a slate, and the intermediate substance, being transparent, now
appears dark.
The lacunae, as already stated, are minute recesses in the bone, and the
lines extending from them are fine pores or tubes named " canaliculi,"
which issue from their cavity. They present some variety of figure, but in
such a section as that represented they for the most part appear irregularly
fusiform, and lie nearly in the same direction as the lamellte between
which they are situated ; or, to speak more correctly, the little cavities
are flattened and extended conformably with the lamellae ; for when the
bone is cut longitudinally, their sections still appear fusiform and length-
ened out in the direction of the lamellae. The canaliculi, on the other
hand, pass across the lamellae, and they communicate with those proceeding
from the next range of lacunae, so as to connect the little cavities with
each other ; and thus, since the canaliculi of the most central range open
into the Haversiau canal, a system of continuous passages is established by
these minute tubes and their lacuuse, along which fluids may be conducted
from the Haversian canal through its series of surrounding lamellae ; in-
deed, it seems probable that the chief purpose of these minute passages is
to convey nutrient fluid from the vascular Haversian canals through the
mass of hard bone which lies around and between them. In like manner
the canaliculi open into the great medullary canal, and into the cavities
of the cancellated texture ; for in the thin bony parietes of these cavities
lacunae are contained ; they exist, indeed, in all parts of the bony tissue.
As first shown by Virchow, each lacuna is occupied by a nucleated cell, or
soft corpuscle, which may be separated from the surrounding substance by
prolonged maceration of decalcified bone in hydrochloric acid or in solu-
tion of potash or soda ; and later observers (Rouget, Neumann,) state that
they are able to detach also the proper osseous wall of the lacuna and its
appertaining canaliculi after decalcification, and to obtain it separate with
its. included corpuscle. The soft corpuscle or cell has an angular outline
corresponding to the shape of the lacuna, but it is not proved that it sends
branches along the canaliculi, as Virchow supposed, or that it has a mem-
branous envelope. Nevertheless, it can scarcely be doubted that the proto-
plasm of the nucleated corpuscle takes an important share in the nutritive
process in bone, and very probably serves both to modify the nutritive
BOXE.
fluid supplied from the blood and to further its distribution through the
lacunar and caualicular system of the bony tissue. Virchow considers that
the corpuscles of bone are homologous with those of connective tissue.
To return to the lamellae. With a little pains, thin films may be peeled
off iu a lougitudin.tl direction from a piece of bone that has been softened
in acid. These for the most part consist of several laminae, as may be
seen at the edge, where the different layers are usually torn unequally, and
some extend farther than others. Examined in this way, under the micro-
scope, the lamellae are seen to be perforated with fine apertures placed at
very short distances apart. These apertures were described by Deutsch,*
but they have not much attracted the notice of succeeding observers ; they
appear to me to be the transverse sections of the caualiculi already de-
scribed, and their relative distance and position accord sufficiently with
this explanation. According to this view, therefore, the canaliculi might
(in a certain sense) be conceived to result from the apposition of a series
of perforated plates, the apertures of each plate corresponding to those of
the plates contiguous with it ; jn short, they might be compared to holes
bored to some depth in a straight or crooked direction through the leaves
of a book, in which case it is plain that the perforations of the adjoining
leaves would correspond ; it being always understood, however, that the
passages thus formed are bounded by proper parietes. The apertures now-
referred to must be distinguished from larger holes seen in some lamellae,
which give passage to the perforating fibres to be mentioned further on.
But the lamellae have a further structure. To
Fig. XLV.
see this, the thinnest part of a detached shred
or film must be examined, as shown in figs. XLV.
and XLVII. ; it will then appear plainly that they
are made up of transparent fibres, decussating
each other in form of an exceedingly fine network.
The fibres intersect obliquely, and they seem to
coalesce at the points of intersection, for they
cannot be teased out from one another ; but at
the torn edge of the lamella they may often be
seen separate for a little way, standing out like
the threads of a fringe. Most generally they
are straight, as represented in the figure ; but
they are not always so, for in some parts they
assume a curvilinear direction. Acetic or hydro-
chloric acid causes these fibres to swell up and
become indistinct, like the white fibres of con-
nective tissue ; care must therefore be taken
in their examination that the remains of the
decalcifying acid be removed from the tissue, by
maceration in water or in solution of an alkaline
carbonate. Moreover, the fibro-reticular struc-
ture is not equally distinct in all parts where
its presence is recognisable ; for in some places
it is less decidedly marked, as if the fibrillation
were incompletely developed resembling in this
respect the areolar and fibrous tissues.
In many instances the lamellae are perforated by fibres, or rather bundles
Fig. XLV. THIN LATER
PEKLKD OFF FROM A SOFT-
ENED BONE, AS IT APPKARS
UNDER A MAGNIFYING
POWER OF 400.
This figure, which is in-
tended to represent the reti-
cular structure of a lamella,
gives a better idea of the
object when held rather
f irther off than usual from
the eye.
* De Penitiori Ossium Structura. Wratisl. 1834, p. 17, Fig. 6.
xcvi BONE.
of fibres, which pass through them in a perpendicular, or more or less
oblique direction, and, as it were, bolt them together. These perforating
fibres may be seen, with the aid of the microscope, in a thin transverse slice
of a decalcified cylindrical or cranial bone, on pulling asunder the sections
of the lamellae (as in fig. XLVL). In this way some lamellae will generally
be observed with fibrous processes attached to them (fig. XLVI. 6) of various
lengths, and usually tapering and pointed at their free extremities, but
sometimes truncated probably from having come in the way of the knife.
These fibres have obviously been drawn out from the adjacent lamellae,
through several of which they must have penetrated. Sometimes, indeed,
indications of perforations may be recognised in the part of the section
of bone from which the fibres have been pulled out (fig. XLVI. c). The pro-
cesses in question are thus, so to speak, viewed in profile ; but they may
frequently also be seen on the flat surface of detached lamellae, projecting
like nails driven perpendicularly or slantingly through a board (fig. XLVII. a) ;
whilst the lamellae at other parts present obvious apertures of considerable
size, through which the perforating fibres had passed (fig. XLVII. 6, 6).
Fig. XLVI.
Fig. XLVI. MAGNIFIED VIEW OP A PERPENDICULAR SECTION THROUGH THE EXTERNAL
TABLE OP A HUMAN PARIETAL BONE, DECALCIFIED.
At a, perforating fibres in their natural situation ; at 6, others drawn out by separa-
tion of the lamellae ; at c, the holes or sockets out of which they have been drawn (H.
Muller).
These perforating fibres, since first noticed by me, have been shown by Kolliker to
exist very generally in the bones of fishes, and to a certain extent in those of
amphibia.* 1 had myself found them abundant in the turtle, and had no doubt of their
general existence in vertebrata. The late lamented Henry Miiller, of Wiirzburg, has
supplied many details respecting their arrangement in man and mammalia, f Kolliker
considers them, to be connected with the periosteum, and this, no doubt, is the case
with some of them some of those, for example, which penetrate the external table of
the cranial bones ; but in cross sections of cylindrical bones they often appear to spring,
with their broad ends, from the deeper lamellae, and taper outwards into fine points,
which do not reach the periosteum ; although without doubt they must, like the bony
layers in which they occur, have been formed by subperiosteal ossification. They are
* Wurzburger Naturw. Zeitschr. vol. i. p. 306. f Ibid, vol. i. p. 296.
BOXE. xcvii
rarely found, and when present are smaller, in the concentric systems of Haversian
lamellae ; in this case they must of course have been formed from the vascular tissue
(similar in nature to that under the periosteum) which occupied the Haversian
spaces and produced the concentric laminae. Perforating fibres exist abundantly in
the crusta petrosa of the teeth.
Fig. XLYII.
vw^*^
Fig. XL VII. LAMELLA TORN OFF FROM A DECALCIFIED HUMAN PARIETAL BONE AT
SOME DEPTH FROM THE SURFACE.
, a lamella, showing reticular fibres ; 6, b, darker part, where several lamellse are super-
posed ; c, c, perforating fibres. Apertures through which perforating fibres had passed,
are seen especially in the lower part, a, a, of the figure. Magnitude as seen under a
power of 200, but not drawn to a scale (from a drawing by Dr. Allen Thomson).
The perforating fibres, or rather bundles of fibres, for the most part agree in
character with the white fibrous tissue, but some, according to H. Muller, are of
the nature of elastic tissue. H. Muller has shown that in some parts the fibres
escape calcification, and thus, as they shrink in drying, leave tubes or channels
in the dry bone, generally leading from the surface inwardly. In this way he
explains the nature and mode of production of the " tubes " described by Tomes and
De Morgan as penetrating the bone in certain situations, and conjectured by them
to be modified lacunae.* I at one time believed that these tubes had no relation to
the perforating fibres, but I have no doubt of the correctness of Miiller's explanation ;
at the same time I am satisfied that uncalcified fibres, though numerous at particular
spots, are by no means so frequent as might be inferred from Miiller's account of
them, and that the perforating fibres may be said to be generally calcified. Finally,
these fibres seem to have no physiological significance : they may be regarded as
merely a modification of the mechanical structure of the tissue.
In a thin transverse section of hard bone, the curved lines, or rather bands which
represent the cut edges of the lamellae, generally present, with transmitted light, a dark
granular-like, and a light, transparent, and usually narrower zone. Under a high
power of the microscope the former appears thickly dotted over with fine dark points.
In a decalcified section the dark part shows a multitude of short bright lines running
radially across it, with dark angular particles between them. The lines are probably
caused by pores and fine clefts passing through the lamella ; the appearance of dark
particles seems to me to be produced by the cut ends of the reticulating fibres of
which it is made up. A longitudinal section of a cylindrical bone carried across the
* Phil. Trans. 1853, p. 116.
xcviii BONE.
lamellae presents a corresponding appearance, for as the fibres run more or less
obliquely to the axis of the bone, they present cut ends in a longitudinal section also.
It thus appears that the amimal basis of bone is made up of lamellae com-
posed of fine reticular fibres ; but interposed among these lamellae, layers are
here and there met with of a different character, viz. :
1. Strata of amorphous or granular aspect, in which the lacunae are very
conspicuous and regularly arranged, and sometimes appearing as if sur-
rounded by faintly defined areol*e. These generally incomplete layers often
terminate by a scalloped border, as if made up of confluent round or oval
bodies; this is indicated also by the occasional occurrence of oval or flattened
spheroidal bodies singly or in small groups near the border of these layers,
each, with a cavity, apparently a lacuna, in the centre. In fact, if the
round bodies shown in figure XLVIII. had a central vacuity, they would
very well represent the objects here referred to. In some parts the granular
substance is obscurely fibrous, and transitions may be observed to the
well-marked reticular laminse. The layers described principally occur, so
far as I have been able to observe, near the surface of the compact
tissue, and at the circumference of many of the systems of concentric
Haversian lamellse.
2. Irregular layers of rounded bodies, apparently solid and without central
cavity or mark, well represented in figure XLVIII., which is after a drawing
from nature by Dr. A. Thomson. I have hitherto met with these layers
chiefly near the surface of the shaft of long bones, lying among the circum-
ferential laminse, and, so far as I can observe, forming only part of a
circuit. They can occasionally be recognised in a transverse section as
short curvilinear bands of peculiar aspect, broader in the middle and thinning
away at the ends, appearing here and there between the cut edges of two
ordinary circumferential larmnse.
The appearances described under 1 and 2, and especially the last, as represented in
fig. XLVIII., suggest the notion of irregular layers of spheroidal bodies, some single,
but mostly confluent in groups, adherent to the subjacent surface ; and one is especially
tempted to this belief by the account given by Gegenbaur * of the deposition of osseous
matter in growing bone at certain points in the form of oval or spheroidal globules,
which in size and aspect would sufficiently answer to the objects above described.
Nevertheless I incline rather to the explanation offered by Professor C. Loven, of
Stockholm, to whom I showed the figure and specimens ; viz., that the surface covered
apparently with globular bodies, single or in botryoidal groups, is really a cast in
relief from a contiguous surface of bone that has been excavated by absorption. It
is known that in the growth of a bone absorption occurs at various parts, and is often
followed by fresh ossific deposition; as, for example, in the excavation and subsequent
filling up of the Haversian spaces. The absorption in such cases is a healthy process,
but the absorbed surface is, as in absorption from disease, eroded or scooped out into
sinuous hollows, the larger of which are again carved on the inside into smaller
rounded pits. New osseous matter deposited on such a surface fills up its hollows, and,
when the new layer is detached, it exhibits a raised impression corresponding with
them.f
* Jenaische Zeitschrift fiir Medizin und Naturwissenschaft. Vol. 1. p. 353.
{ Two observations which I have had occasion to make favour this explanation. A
cross section of a (large) serpent's rib shows an outer and an inner series of concentric
lamellae surrounding the medullary canal, and the inner trenches on the outer by a festooned
border such as often bounds a series of Haversian rings. Now, in the decalcified rib, it is
easy to peel off the inner from the outer layers, and the detached surface of the former
shows a number of oval eminences, some with one, others with two, three, or more lacuna?
in their substance ; whilst what was the contiguous surface of the outer layers has exca-
vations that correspond. Again, in the grinding tooth of the horse, the surface of the
BOXE.
Ossified cartilage is found on the articular ends of adult bones, lying
underneath the natural cartilage of the joint, both in the moveable articu-
Fig. XLYIIT.
Fig. XLVIII. PORTION OP A NOLULATED LATER OP BONE-TISSUE PROM NEAR THK
SURFACE OP THE SHAFT OF A DKCALCIFIED IlUMKRUS.
At one side shreds of fibrous lamellae are seen in the figure.
diameters.
Magnified 300
lations and in symphyses, and is in fact the deeper part of the cartilage
which has been encroached upon by the calcifying process. The animal
basis is here, however, of a totally different nature from that of the bone
crusta petrosa which is contiguous to the dentine or to the enamel, is marked over with
spheroidal bodies having, in decalcified specimens, very much the appearance represented
in Fig. LXVI1I., but most of them with one or more lacuna-like cavities within. They
look very like distinct globules, and have been described by Czermak as calcified cells
containing lacunae ; but on carefully viewing the decalcified layer in profile-sections and
otherwise, I am led to the conclusion that they are mammillary elevations of the surface,
continuous by their (sometimes contracted) bases with the general substance. The enamel
is destroyed in the decalcification, but the surface of the dentipe. of the ccrvi* and \foot
from which the inammillated layer of c*u&ta<; p^tfasa has, hem, detached,* i^fciundJtb" be
excavated in a manner to correspond with it f ; e ^ juTangerapnS ^ell calculated 'iV secure
their mutual connection. , , -, .,->, "
c BONE.
beneath ; for, when the earthy matter is extracted by means of an acid, the
tissue which remains has all the characters of cartilage.
As to the mode in which the earthy matter is connected with the animal
substance, we know that the combination is very intimate, but the manner
in which it is effected is not fully understood ; probably there is a chemical
union between the collagenous matter and the earthy salts.
The periosteum, as already stated, is a fibrous membrane which covers
the bones externally. It adheres to them very firmly, and invests every
part of their surface, except where they are covered \vith cartilage or con-
nected to other bones by tibro- cartilage. According to Kolliker it is com-
posed of two different layers ; the outer, consisting of white fibres, and
containing occasional fat-cells, is the means of supporting numerous blood-
vessels destined for the bone, which ramify in the membrane, and at length
send their minute branches into the Haversian canals of the compact sub-
stance, accompanied by processes of filamentous tissue derived from, or at
least continuous with, the periosteum. The inner layer is made up of
elastic fibres ; and frequently presents the appearance of several distinct
strata of "elastic membrane." Fine nervous filaments spread out in the
periosteum ; they are chiefly associated with the arteries, and for the most
part destined for the subjacent bone ; but some are for the membrane
itself.
The chief use of this membrane is evidently to support the vessels going to the
bone, and afford them a bed in which they may subdivide into fine branches, and so
enter the dense tissue at numerous points. Hence, when the periosteum is stripped
off at any part, there is great risk that the denuded portion of the bone will die and
exfoliate. The periosteum also contributes to give firmer hold to the tendons and
ligaments where they are fixed to bones; indeed, these fibrous structures become
continuous and incorporated with it at their attachment.
The marrow (medulla ossium) is lodged in the interior of the bones ; it
fills up the hollow shaft of long bones and occupies the cavities of the
cancellated structure ; it extends also into the Haversian canals at least
into the larger ones along with the vessels. Like ordinary adipose tissue,
it consists of vesicles containing fat, with blood-vessels distributed to them.
A fine layer of a highly vascular areolar tissue lines the medullary canal, as
well as the smaller cavities which contain marrow ; this has been named the
medullary membrane, internal periosteum, or endosteum ; but it cannot be
detached as a continuous membrane. Its vessels partly supply the con-
tiguous osseous substance, and partly proceed to the clusters of adipose
vesicles, among which there is but very little connective tissue, in conse-
quence perhaps of their being contained and supported by bone.
The marrow differs considerably in different situations. Within the shaft of the
long bones it is of a yellow colour, and contains, in 100 parts, 96 of fat, 1 of con-
nective tissue, and 3 of water. In short bones, and in the cancellated ends of long
bones, but especially in the cranial diploe, the bodies of the vertebrce, the sternum,
and the ribs, it is red or reddish in colour, of more fluid consistence, and with very
few fat-cells. That from the diploe consists of 75 parts of water and 25 of solid
matters, which are chiefly albumen, fibrin, extractive and salts, with mere traces of
fat. While, however, the fat-cells are scanty in the red-coloured marrow, it contains
minute tyundislv $u elected, cells the proper marrow-cells of Kolliker. These, which
include BO, fat n corsespoiicfin character jwhb, th,e cells found in the articular ends of
long bones' affecVed wit hvperceijr.iai' tk r eji)cc?ur normally in the cranial bones, ver-
BOXE. ci
tebrse, and sternum, and in variable number in the scapula, the innominate, and
facial bones.
The marrow serves the same general purposes in the economy as ordinary fat.
Placed within the bones, which are made hollow for the sake of lightness, it serves as
a light and soft material to fill up their cavities and support their vessels. In birds,
for the sake of still further lightening their skeleton, the larger bones, instead of
being filled with marrow, contain air, which passes into them from the lungs by
openings at their extremities. Even in man there are certain hollow bones of the
cranium and face which are naturally filled with air. The cavities of these bones are
named sinuses; they open into the adjoining air-passages, and are lined with a
prolongation of the mucous membrane, underneath which is a thin periosteum, "
The bones do not at first contain fatty marrow ; in the foetus their cavities are
filled with a transparent reddish fluid, like bloody serum, only more consistent and
tenacious, with granular marrow-cells. In dropsical subjects also, the marrow, like
the rest of the fat, is consumed to a greater or less extent, its place being occupied by
a serous fluid.
Blood-vessds. The bones are well supplied with blood-vessels. A net-
work of periosteal vessels covers their outward surface ; others penetrate to
the cavities of the spongy part and the medullary canal, on the sides of
which they ramify ; and fine vessels, deprived of their muscular coat, run
through all parts of the compact tissue in the Haversian canals. The sides
of these internal cavities and canals make up together a large extent of
inward surface on which vessels are srread. The nutritious fluid conveyed
by these vessels no doubt escapes through their coats and permeates the
surrounding dense bone interposed between the vascular canals ; and it
seems highly probable that the system of lacunas and communicating canali-
culi, already described, is a provision for conducting the exuded fluid
through the hard mass. When a bone is macerated, its vessels and mem-
branes are destroyed, whilst the intermediate true bony matter, being of an
incorruptible and persistent nature, remains ; a process which, for obvious
reasons, cannot be effected with the soft tissues of the body.
The vessels of bone may be recognised while it is yet fresh by the colour
of the blood contydued in them ; but they are rendered much more con-
spicuous by injecting a limb with size and vermilion, depriving the bones
of their earth by means of an acid, and then drying them and putting them
into oil of turpentine, by which process the osseous tissue is rendered trans-
parent whilst the injected matter in the vessels retains its red colour and
opacity. Numberless small vessels derived from the periosteum, as already
mentioned, pass along the Haversian canals in the compact substance.
These are both arterial and venous, but, according to Todd and Bowman,
the two kinds of vessels occupy distinct passages ; and the veins, which are
the larger, present, at irregular intervals, pouch-like dilatations calculated to
serve as reservoirs for the blood, and to delay its escape from the tissue.
Arteries, of larger size but fewer in number, proceed to the cancellated
texture. In the long bones numerous apertures may be seen at the ends,
near the articular surfaces ; some of these give passage to the arteries
referred to, but the greater number, as well as the larger of them, are for
the veins of the cancellated texture, which run separately from the arteries.
Lastly, a considerable artery goes to the marrow in the central part of the
bone ; in the long bones this medullary artery, often, but improperly, called
" the nutritious artery," passes into the medullary canal, near the middle of
the shaft, by a hole running obliquely through the compact substance. The
vessel, which is accompanied by one or two veins, then sends branches
upwards and downwards to the marrow and medullary membrane in the
eii BONE.
central cavity and the adjoining Haversian canals. Its ramifications anas-
tomose with the arteries of the compact and cancellated structure ; indeed,
there is a free communication between the finest branches of all the vessels
which proceed to the bone, and there is no strictly defined limit between
the parts supplied by each. In the thigh-bone there are two medullary
arteries entering at different points.
The veins of the cancellated texture are peculiar and deserve special
notice. They are large and numerous, and run separately from the arteries.
Their arrangement is best known in the bones of the skull, where, being
lodged in the diploe or spongy texture between the outer and inner compact
tables, they have received the name of the diploic veins. They run in
canals formed in the cancellated structure, the sides of which are con-
structed of a thin lamella of bone, perforated here and there for the admis-
sion of branches from among the adjoining caucelli. The veins, being thus
inclosed and supported by the hard structure, have exceedingly thin coats.
They issue from the bone by special apertures of large size. A similar
arrangement is seen in the bodies of the vertebrae, from whence the veins
come out by large openings on the posterior surface.
The lymphatics of the bones are but little known ; still, there is evidence
of their existence, for, independently of the authority of Mascagni (which
is of less value in this particular instance, inasmuch as he does not state
expressly that he injected the vessels which he took for the lymphatics of
bone), we have the testimony of Cruikshank, who injected lymphatics
coming out of the body of one of the dorsal vertebrae, in the substance of
which he also saw them ramifying.*
Fine nerves have been seen passing into the medullary canal of some of
the long bones along with the artery, and following its ramifications, but
their ultimate distribution is doubtful ; and Kolliker describes fine nervous
filaments as entering with the other arteries of the bone to the spongy and
compact tissue. As far, however, as can be judged from observations on
man and experiments on the lower animals, the bones, as well as their
investing periosteum, are scarcely if at all sensible in the healthy condition,
although they are painfully so when inflamed.
Some hold that the same is true of the marrow, or rather the medullary membrane ;
others, among whom are Duverney and Bichat, affirm, on the contrary, that the
medullary tissue is sensible. They state that, on sawing through the bone of a living
animal, and irritating the medullary membrane by passing a probe up the cavity, or
by injecting an acrid fluid, very unequivocal signs of pain will be manifested.
Beclard, who affirms the same fact, points out a circumstance which may so far
account for the result occasionally turning out differently, namely, that when the
bone happens to be sawn through above the entrance of the medullary artery, the
nerves going along with that vessel are divided, and the marrow consequently ren-
dered insensible, as happens with any other sensible part when its nerves are cut.
Formation and grou'th of bone. The foundation of the skeleton is laid at
a very early period ; for, among the parts that appear soonest in the embryo,
we distinguish the rudiments of the vertebrae and base of the skull, which
afterwards form the great median column to which the other parts of the
bony fabric are appended. But it is by their outward form and situation
only, that the parts representing the future bones are then to be recognised ;
for at that early period they do not differ materially in substance from the
other structures of the embryo, being, like these, made up of granular
* Anatomy of the Absorbing Vessels, 1790, p. 198.
BONE.
corpuscles or elementary cells, united together by a soft amorphous matter.
Very soon, however, they become cartilaginous, and ossification in due time
beginning in the cartilage and continuing to spread from one or from several
points, the bone is at length completed.
But, while it is true with respect to the bones generally that their ossifi-
cation commences in cartilage, it is not so in every instance. The tabular
bones, forming the roof of the skull, may be adduced as a decided example
to the contrary ; in these the ossification goes on in a membranous tissue
quite different in its nature from cartilage ;* and even in the long bones,
in which ossification undoubtedly commences and to a certain extent pro-
ceeds in cartilage, it will be afterwards shown that there is much less of the
increment of the bone really owing to that mode of ossification than has,
till lately, been generally be-
lieved. It is necessary, there- Fig. XLIX.
fore, to distinguish two spe-
cies or modes of ossification,
which for the sake of brevity
may be called the intramem-
branous and the intracartila-
ginous.
Ossification in membrane.
The tabular bones of the
cranium, as already said,
afford an example of this
mode of ossification. The
base of the skull in the em-
bryo is cartilaginous ; but iu
the roof, that is to say, the
part comprehending the pari-
etal, the upper and greater
part of the frontal, and a
certain portion of the occipital
bones, we find (except where
there happen to be commenc-
ing muscular fibres) only the
integuments, the dura mater,
and an intermediate mem-
branous layer, which differs
from cartilage in its intimate
structure as well as in its
more obvious characters, and
in which the ossification pro-
ceeds.
The commencing ossifica-
tion of the parietal bone,
which may be selected as an
example, appears to the naked
eye in form of a net-work in
which the little bars or spicula of bone run in various directions, and meet
each other at short distances. By and by the ossified part, becoming
* This fact was pointed out and insisted on by Dr. Nesbitt, who distinguishes the two
different modes of ossification, and so far his riews are quite correct. See his human
Osteogeny, Lond. 1736.
Fig. XLIX. PARIETAL BONE OP AN EMBRYO
SHEEP. SIZE OP THE EMBRYO, 2^ INCHES.
The small upper figure represents the bone of the
natural size, the larger figure is magnified about 12
diameters. The curved line, a, b, marks the height
to which the subjacent cartilaginous lamella ex-
tended. A few insulated particles of bone are seen
near the circumference, an appearance which is quite
common at this stage.
civ BONE.
extended, gets thicker and closer in texture, especially towards the centre,
and the larger bony spicula which now appear, run out in radiating lines to
the circumference. The ossification continues thus to spread and consolidate
until the parietal meets the neighbouring bones, with which it is at length
united by suture.
The figure (XLIX.) represents the parietal bone of an embryo sheep about
two inches and a half long, and shows the character of the ossification as
it appears when the object is magnified about twelve diameters. The bone
is formed in membrane as in the human foetus, but a thin plate of cartilage
rises up on its inside from the base of the skull. The ossification, however,
is decidedly unconnected with the cartilage, and goes on in a membrane
lying outside of it. The cartilaginous plate is not represented in the figure,
but a dotted curve-line, a, b, near the top, marks the height to which it
reached, and from this it will be seen that the ossification extended beyond
the cartilage. In the region of the frontal bone the cartilage does not even
rise so high. In both cases its limit is well defined, and under the micro-
scope it presents a decided contrast to the adjacent membrane.
When further examined with a higher magnifying power, the tissue or
membiane in which the ossification is proceeding, appears to be made up
of fibres and granular corpuscles, wich a soft amorphous or faintly granular
uniting matter, and, in point of structure, might not unaptly be compared
to connective tissue in an early stage of development. The corpuscles are
large, mostly two or three times the size of blood-corpuscles ; their sub-
stance is granular in character, and, especially in specimens preserved in
spirit, usually hides the nucleus. They are densely packed all over the
area of ossification, covering the bony spicula, and filling up their inter-
stices ; so that, to bring the growing parts into view, the corpuscles must
be washed away with a hair pencil, or removed by short immersion of the
specimen in weak solution of soda.
On observing more closely the points of the growing osseous rays at the
circumference of the bone, where they shoot out into the soft tissue, it will
be seen that the portion of them already calcified is granular and rather dark
in appearance (fig. L., a, b, c), but that this character is gradually lost as
they are traced further outwards in the membrane, in which they are pro-
longed for a little way in form of soft and pliant bundles of transparent fibres
(fig. L.,/). Further inwards, where the slender rods or bars of bone are
already in great part hard, their calcified substance is coated over (although
unequally) with transparent and as yet soft and imperfectly calcified matter,
by which they grow in thickness ; and this ossifying substance spreads out
at their sides, and encroaches on the intervening space, in form of a bright
trellis-work (fig. L., d), thin towards its outer limit, and there composed of fine
fasciculi, but denser and coarser nearer the bone, where the trabeculse are
thick and round, and already granular from commencing earthy impregna-
tion.* The interstices of this mesh- work are in some parts occupied by one
or more of the corpuscles, but at other parts they are reduced to short narrow
clefts or mere pores. The appearance which I have endeavoured to describe
is especially well seen at those places where a cross bridge of bone is being
formed between two long spicula (as at e) ; we may there distinguish the clear
* A notion of this appearance may also be obtained from Fig, LVIII,, page cxiii., which
represents intramembranous ossification advancing under the periosteum of a long bone.
From a to c is the ossifying trellis-work, but coarser than in the early cranial bone.
From, a to b is the part already impregnated with earthy deposit, which is encroaching on
the part b, c, as yet soft and pellucid.
BOXE.
Fig. L.
soft fibres or trabeculse which have already stretched across the interval ; and
the darkish granular opacity indicating the earthy deposit (a, a') may be per-
ceived advancing into them and shading off gradually into their pellucid
substance without a precise limit. Tins soft transparent matter, which
becomes ossified, may, wherever it occurs, be distinguished by the name of
" osteogenic substance," as proposed by H. Miiller, or simply of " osteogen."
It is or becomes fibrous in intimate structure, and for the most part finely
reticular, like the decalcified bone itself, but must not be confounded with
fibres which may pre-exist in the membranous tissue in which the bone is
growing.
The granular corpuscles or cells everywhere cover in a dense layer the
osteogenic substance, and lie
in its meshes; most probably
they yield or excrete that
substance, and hence it has
been proposed to call them
" osteoblasts." On this view
the process might be com-
pared to the production, by
cells, of the matrix of carti-
lage and the intercellular
fibrillatiug substance ingrow-
ing connective tissue ; also
to the excretion of mem-
branous, cuticular, and other
deposits by cells, and layers
of cells, long since pointed
out by Kolliker.
But some of the granular
cells are involved in the ossi-
fying matrix, and eventually
inclosed in lacunae. Single
cells may accordingly be seen
partially sunk in the recent
osteogenic deposit, which
then gradually grows over
them and buries them in its
substance ; and the cavity in
which the corpuscle is thus
inclosed becomes a lacuna.
a, b, c, and a', parts already calcified; d, d, irre-
gular network of soft and pellucid osteogenic sub-
stance, on which the calcification is encroaching ;
a, e, a', a connecting bar or bridge still soft at e, but
calcified at a and a' /, extremity formed of bundles
of soft osteogenic fibres. N.B. the structure repre-
sented was covered over and hidden by granular cor-
puscles which have been removed. In the calcified
part, a, b, c, superficial excavations are seen which
are probably commencing or incomplete lacunae, from
which the corpuscles have been washed out. From a
drawing by Mr. J. Marshall, F.R.S.
Fig. L. THE GROWING END OP A SPICULUM FROM
THK PARIETAL BONE OP AN EMBRYO SHEEP at about
the same period of advancement as in Fig. XLIX. ;
magnified 150 diameters, but drawn under a power
of 350 diameters.
Some observers state that,when
such a corpuscle is as yet but
half sunk in the growing sub-
stance, processes may be seen
passing from the imbedded side
into fine clefts of the matrix,
which close in around them and
become the canaliculi ; and that,
as the inclosure of the corpuscle
is completed, canaliculi are in
like manner formed in the rest
of its circumference. It is also
supposed that the canaliculi are afterwards extended by absorption, so as to anas-
tomose with those of neighbouring lacunse. But from all I can see of the process,
it seems more probable that, whilst the ossific matter closes in around the corpuscle
cvi BONE.
and forms the lacuna, the canaliculi and their communications may be merely channels
left as vacuities in the osseous deposit, into which the processes of the now stellate
corpuscle pass but a short way.
As the bone extends in circumference, it also increases in thickness ; the
vacuities between the bony spicula become narrowed or disappear, and at a
more advanced period the tabular bones of the cranium are tolerably compact
towards the centre, although their edges are still formed of slender radiating
processes. At this time also numerous furrows are grooved on the surface
of the bone in a similar radiating manner, and towards the centre these are
continued into complete tubes or canals in the older and denser part, which
run in the same direction. The canals, as well as the grooves, which become
converted into canals, contain blood-vessels supported by processes of the
investing membrane, and are lined with granular cells, which deposit con-
centric layers of bone inside these channels ; and, when thus surrounded with
concentric laminae, these tubular cavities are in fact the Haversian canals.
Fig. LI. I may here observe that in earlier stages, such as that
shown in fig. XLIX., vessels may be seen in the soft tissue, some
twice or three times the size of a blood-capillary, others con-
siderably more, but all with only a homogeneous coat with
cells upon it here and there, and without a muscular layer.
Ossification in cartilage. It has already been stated
that, in by far the greater number of bones, the primitive
soft cellular matter of which they originally consist is
very quickly succeeded by cartilage, in which the
ossification begins. One of the long bones taken from
a very small embryo, just before ossification has com-
menced in it, is observed to be distinctly cartilaginous.
In the tibia of a sheep, for example, at a time when
the whole embryo is not more than an inch and a
quarter in length, we can plainly see that the substance
consists of cartilage-cells imbedded in a pellucid matrix.
These cells, which can scarcely be said to be collected
into groups, are much larger in the middle part of the
shaft where ossification afterwards commences, and
there also they are mostly placed with their long
diameter across the direction of the bone : towards the
ends they are much smaller and closer together, and
the cartilage there is less transparent. As it enlarges
the cartilage acquires firmer consistence ; it represents
in figure the future bone, though of course much
smaller in size, and it is surrounded with a fibrous
membrane or perichondrium, the future periosteum.
Vessels ramify in this membrane, but none are seen iu
the cartilage until ossification begins.
In a long bone the ossification commences in the
middle and proceeds towards the ends, which remain
long cartilaginous, as represented in fig. u. At
length separate points of ossification appear in them, and form epiphyses,
which at last are joined to the body of the bone.
The newly formed osseous tissue is red and obviously vascular, and blood-
vessels extend a little way beyond it into the adjoining part of the cartilage.
Fig. LI. HUMERUS
OF A FCETUS, NATU-
RAL SIZE.
The upper half is
divided longitudinal-
ly, a, cartilage, b,
bone, which termin-
ates towards the car-
tilage by a slightly
convex surface.
BONE. cvii
la a long boiie these precursory vessels are seen at either end of the ossified
portion of the shaft, forming a red zone in that part of the cartilage ID to
which the ossification is advancing. The vessels are lodged in excavations
or 1 ranching canals in the cartilage, (fig. LI. a,) which also contains granular
corpuscles and soft matter. Other vascular canals enter the cartilage from.
its outer surface, and conduct vessels into it directly from, the perichondrium;
at least, this may be seen when the ossification approaches near to the ends
of the bones.
Dr. Baly has observed that in a transverse section of the ossifying cartilage, its
cells appear arranged in radiating lines round the sections of the vascular canals ; *
and I may also remark that in many of these radiating groups the cells successively
diminish in size towards the centre, that is, as they approach the canal. The canals
which enter from the surface of the cartilage are probably formed by processes from
the vascular subperichondrial tissue, which, excavating the canals by absorption,
thus extend themselves through the mass of cartilage; and as the perichondrium
affords material for the growth of the cartilage at the surface, so these vascular pro-
cesses probably yield matter for the multiplication of the cells in the interior of the
mass. The canals which pass into the cartilage from the ossified part are, in like
manner, most probably formed by processes of the subperiosteal tissue which pierce
the bone and extend through the medullary cavities within it to the cartilage, into
which they penetrate for a short way beyond the advancing limit of ossification.
To examine the process more minutely, let an ossifying bone be divided
lengthwise, as in fig. LI. , and then from the surface of the section (as at a, 6)
take off a thin slice of cartilage, including a very little of the ossified
part, and examine it with the microscope. Such a view, seen with a
low power, is shown in fig. LII. The cartilage at a distance from the sur-
face of the ossified part has its cells uniformly disseminated in the matrix,
(as at a, where it appears in the figure as if granular,) but at and near to the
limit where the ossification is encroaching upon it, the cells are gathered into
rows or oblong groups, between which the transparent matrix appears in form
of clear longitudinal lines (often obscurely striated) obliquely intersecting each
other (6). Tomes and De Morgan state that these rows are formed by
segmentation of the cartilage-cells transversely to the line of ossi6c advance.
Turning now to the newly formed bone (c), which from its dark opaque
aspect contrasts strongly with the cartilage, and tracing it towards their
mutual boundary, we see plainly the dark lines of ossification shooting up
into the clear spaces of the cartilage between the groups of corpuscles. The
earthy deposit, in fact, proceeds through the matrix, and affects also those
parts of the cartilage-capsules which form the circumference of a group, so
that the new osseous substance forms in the first instance oblong areolse or
loculi, which inclose the groups of cells. This is further illustrated by a
thin transverse section, carried nearly parallel to the ossifying surface, and
partly encroaching on it, so as to take off a little of the bone along with
the cartilage, as represented in fig. LIII. In this view we see, at one part,
the dark and nearly circular sections of the newly formed osseous areolae ;
at another, sections of the rows of cartilage- cells with the clear matrix
between and around them, and into this the dark ossification is advancing.
On using a higher power, as in figs. LIV. and LV., it will be seen that the cells
forming the groups are placed with their long diameter transversely, as if they had
been flattened and piled upon one another ; but in the immediate vicinity of the bone
they become greatly enlarged and more rounded. In most of them the outline
of the capsule is distinct from that of the mass within. As to the matter they
* Muller's Physiology, plate I., fig. 16.
cviii
BONE.
contain, in some it is a pellucid substance strongly refracting the light, and nearly
filling the capsule ; in others it is faintly granular and light like ground glass, and
has a well-defined outline, and in these there is a very distinct nucleus, varying much
in size in different cells, but always most regularly circular, and inclosing one or
more nucleoli ; lastly, a good many cells may be seen, in which the contained mass
or cell-body has shrunk and does not nearly fill the capsule, and then it is usually
coarsely granular or grumous, with an uneven, and in some, a jagged outline.
Fig. LIT.
Fig. LTII.
Fig. LIT. THIN LONGITUDINAL SECTION OP OSSIFYING CARTILAGE PROM THE HUMERUS
OF A F<ETAL SHEEP.
a, cartilage-cells uniformly diffused ; b, cells nearer the boundary of the ossification,
collected into piles and inclosed in oblong areolse of the clear matrix ; c, dark lines of
ossification extending into the matrix and forming the primary bony areolee. Magnified
about 70 diameters.
Fig. LIII. TRANSVERSE SECTION OF THE OSSIFYING CARTILAGE REPRESENTED IN
Fig. LIL,
Made a little above c, along the surface of ossification, and including part of the new-
bone, magnified 70 diameters. The circular sections of the groups of cells and of the
osseous areolse are seen ; and the dark bone extending into the clear intercellular
matrix.
It thus appears that the bony tissue, as it advances into the cartilage,
has at first a sort of alveolar structure, made up of fusiform areolce, or
short tubular cavities, with thin parietes, which are formed by calcifi-
BOXE.
cation of the matrix and partial calcification of the capsules of the cartilage-
cells. But this condition, which differs from that of perfect bone, is only transi-
tory, and at a short distance below the ossifying surface we see a change
taking place in the newly formed tissue ; the structure becomes more
open, the original cartilage-cells disappear from its interstices, and the
medullary spaces, with their lainellated parietes, as in the permanent cancel-
lated tissue, begin to be formed. This, which is the next step of the
process, takes place in the following manner. The primary areolce of the
bone above described open into one another
both laterally and longitudinally by absorp- pj_ j^y
tion of their intermediate walls, and by
their confluence give rise to the larger or =^ S :== S, ^. ^ ^ ^,
secondary cavities, the medullary spaces of sSS^SM^^
H. Miiller, which succeed them lower down. '\~k' = ^ = ?= "^"^S ^
This is shown in a longitudinal section in IE =" jj^ Sf <H i 3>' = L
fig. LV., and in transverse section in fig. LVI.,
A, which represents a thin section made
almost immediately below the surface of
ossification, and in which the primary cavi-
ties are seen to have coalesced into larger
ones. A transverse section somewhat lower
down, (fig. LVI., B,) shows that they go on
enlarging by further absorption and coales-
cence, and that their sides are thickened
by layers of new bone ; this soon begins to
be deposited, (fig. LV., 6, 6, in longitudinal,
and LVL, A, in cross section) and goes on
increasing, (fig. LVI., B). In the meantime
the cartilage-cells have disappeared, and the
bony cavities are filled with soft matter,
in which there are a few fibres and numerous
granular corpuscles resembling those seen in
the intrainembranous ossification (d, fig.
LV.) ; there are also many blood-vessels.
In the end
and open
cancellated tissue, but much of this struc-
ture is afterwards removed by absorption,
to give place to the medullary canal of
the shaft. In many of these cavities the
walls of the coalesced primary areolae may
long be distinguished, like little arches,
forming by their union a sort of festooned
outline, within which the new bony laminae
are situated.
, some of the enlarged cavities
structure remain to form the
Fig. LIV. SMALL PORTION OF A
SECTION SIMILAR TO THAT IN FIG.
LIL, MORK HIGHLY MAGNIFIED
(ABOUT 140 DIAMETERS).
a, b, two of the new-formed osse-
ous tubes orareolae, with a few car-
tilige-cells and granular corpuscles
lying in them ; c, c, cartilage-cells
near the ossifying surface, exhibiting
the appearance described in the text.
The primary osseous matter forming the original thin walls of the areolse, and
produced by calcification of the cartilaginous matrix, is decidedly granular, and
has a dark appearance ; the subsequent or secondary deposit on the other hand is
quite transparent, and of an uniform, homogeneous aspect. This secondary deposit
begins to cover the granular bone a very short distance (about ^th of an inch) below
the surface of ossification, and, as already stated, increases in thickness further down.
The lacunae first appear in this deposit ; there are none in the primary granular bone.
The cartilage-cells do not become calcined. According to H. Miiller the capsules
EOXE.
Fig. LV.
are opened by absorption, and the granular bodies contained within them (i.e.
the proper cell-bodies) produce by fissi-
parous multiplication the granular osteo-
blastic cells which succeed them. On
the other hand, Love"n* has suggested,
and, as I think, with more probability,
that the osteoblastic corpuscles properly
belong to the vascular processes of the
subperiosteal tissue, which, as already
stated, penetrate the newly formed bone
and spread throughout its cavernulated
structure. The excavation and removal
of the cartilage, as well as the partial
absorption of the walls of the bony cavi-
ties, is no doubt effected by this tissue,
and the abundant osteoblastic cells which
appear in it are most probably derived
by descent from similar cells equally
abundant beneath the periosteum. The
cells or corpuscles in question, in what-
ever way produced, are disposed in a layer
or layers upon the walls of the secondary
or medullary spaces, in immediate con-
tact with the new osteogenic deposit,
which here, as in the intramembranous
ossification, they probably secrete. Here
too the osteogenic substance is finely
reticular, and retains that character when
calcified ; for the secondary bony deposit
is formed in layers made up of finely
reticulating fibres, like the lamellae of
perfect bone shown in fig. XLV. On a
careful inspection, and M'ith a certain
adjustment of the light, fine striae may
be seen in many parts indicating the
obliquely decussating fibres of the newly
formed laminae. The structure in some
measure reminds us of the secondary
deposit inside the oblong cells of the
wood of coniferous trees, in which the
ligneous matter is arranged in fibres, or
rather in fine lines, running obliquely
round the wall of the cell and crossing
one another in alternate layers.
The lacunas are formed, as described
in the intramembranous ossification, by
some of the granular corpuscles becom-
ing imbedded in the osteogenic sub-
stance, and inclosed in a cavity formed
round them by its further deposit. La-
cunae formed from cartilage-cells exist
but very scantily. Examples occur in
articular cartilage, and in that of the
pubic symphysis, when, as commonly
happens in mature life, the part of these
tissues adjoining the bone is encroached
on by a species of ossification, as noticed
at page xcix. The ossifying process in
this case is mere calcification of the
cartilage, and stellate lacunae, not inter-
Fig. LV. THIN LONGITUDINAL SECTION OP
THE GROWING END OF THE SHAFT OF THE
METATARSAL BONE OF A SLINK CALF,
MAGNIFIED.
The upper part of the figure shows four
groups of cartilage cells, with calcified matrix
between them forming the walls of four
primary areolse filled as yet by the original
cartilage cells, except at the lower part where
these are replaced by granular corpuscles.
Lower clown are two oblong spaces (secondary
or medullary cavities) ; one, indicated by d,
is nearly filled by granular corpuscles and
vessels, the other is vacant. The walls of
these spaces are beginning to be lined with
secondary osseous deposit, shown in the
figure as a lighter layer, &, &, and b ; c, c,
and c, are corpuscles about to be imbedded
in the ossifying substance and inclosed in
laminse; g, a cartilage cell of which the body
has shrunk from the inside of the capsule.
After H. Miiller and Kolliker.
* Studier och Undersokningar ofver Benvafnaden. Stockholm. ]863.
BONE. C xi
communicating by canaliculi, remain in the partially ossified cells. When this
hard tissue is decalcified by an acid, the original cells and cartilaginous matrix
become apparent.
Fig. LTL, A.
Fig. LYL, B.
Fig. LVL A AND B REPRESENT TWO TRANSVERSE SECTIONS OP GROWING BoNE, AS IN
FlQ. LIIL, BUT MUCH MORE MAGNIFIED (ABOUT 120 DIAMETERS).
They show the lateral coalescence of the primary bony areolae and the thickening of the
sides of the enlarged cavities by new osseous deposit. The section A is made almost imme-
diately below the surface of ossification ; B, is somewhat lower, and shows the cavities still
more enlarged and their sides more thickened than in A. The new osseous lining is
transparent, and appears light in the figures ; the dark ground within the areolse is owing
to opaque debris, which collected there in grinding the sections. It must be further
noticed that the letter A within the larger figure, marks a place where a bony partition
had been accidentally broken away, for the large space was naturally divided into
two.
As ossification advances towards the ends of the bone, the portion as yet
cartilaginous continues to grow at the same time, and increases in every
dimension. The part already osseous increases also in circumference ; the
medullary canal, of which for some time there is no appearance, begins to
be excavated in the interior by absorption, and the sides of the shaft acquire
,
BONE.
LYIL
compactness and soliJity. The increase in girth is brought about by
deposition of bone at the surface underneath the periosteum. It has been
sometimes supposed that a formation of cartilage precedes the bone also in
this situation ; but such is not the case,
for the vascular soft tissue in immediate
contact with the surface of the growing
bone is not cartilage, but a blastema con-
taining fibres and granular corpuscles ; in
fact, the increase takes place by intra-
membranous ossification, and accordingly the
Haversiau canals of the shaft are formed in
the same way as those of the tabular bones
of the skull, that is, the osseous matter is
not only laid on in strata parallel to the
surface of the bone, but is deposited around
processes of the vascular membranous tissue
which extend from the surface obliquely into
the substance of the shaft, (fig. LVII., a, a, in
transverse section); and the canals in which
these vascular processes lie, becoming nar-
rowed by the deposition of concentric osseous
laminae, eventually remain as the Haversian
canals (c, c).
Fig. LYII. TRANSVERSE SECTION
OF SUPERFICIAL PART OF GROW-
ING METATARSAL BONE OF A
CALF, MAGNIFIED 45 DIAMETERS
(from Kolliker).
A, periosteum ; B, vascular soft
tissue (subperiosteal blastema of
some writers) ; C, new bony
growth with wide spaces, a, , a,
some being open grooves, others
tubular, seen in cross section ; D,
more advanced and now compact
tissue of the shaft, with the tubular
spaces now nearly filled with con-
centric lamellae leaving Haversian
canals, c, f, in the centre. With
a higher magnifying power, in the
tissue B would be found fibres and
granular cells, and layers of these
cells everywhere covering the
osteogenic deposit on the surface
of the growing bone, and lining
the grooves and tubular spaces.
That the ossification at the periosteal surface of
the bone does not take place in cartilage, may be
made apparent in the following manner. Strip
off the periosteum from a growing bone at the end
of the shaft, and from the adjoining cartilage
also, taking care not to pull the latter away
from the bone. A thin membranous layer will
still remain, passing from the bone over the
cartilage ; now, take a thin slice fronV the surface,
including this membrane with a very thin portion
of the subjacent bone and cartilage, and examine it
with the microscope, scraping off the cartilage
from the inside if it be too thick. It will then
be seen that the superficial part or shell of the
bone, if it may be so called, is prolonged a little
way over the surface of the cartilage by means of
pellucid, coarsely reticulated fibres of soft tissue (fig. LVIII. 6, c) into which the earthy
deposit is advancing. These osteogenic fibres are intermixed with granular corpuscles
or cells, but form no part of the cartilage, and they are no doubt of the same
nature as those seen in the intramembranous ossification of the skull. Their
reticulations are in most cases directed transversely, and sometimes they are little,
if at all, in advance of the limit between the bone and cartilage. I have observed
the structure here described in several bones of the (well-advanced) foetal sheep,
also in the human scapula, humerus, femur, tibia, and fibula, metacarpus and meta-
tarsus ; and, as was to be anticipated, it has since been found in all the long bones.
Ossification having thus proceeded for some time in the shaft, at length
begins in the extremities of the bone from one or more independent centres,
and extends through the cartilage, leaving, however, a thick superficial
layer of it unossified, which permanently covers the articular end of the
bone. The epiphyses thus formed continue long separated from the shaft
or diaphysis by an intervening portion of cartilage, which is at last ossified,
and the bone is then consolidated. The time of final junction of the
BOXE.
Fig. LVIII.
epiphyses is different in different bones ; in many it does not arrive until
the body has reached its full stature. Meanwhile the bone increases in
length by the ossification continuing to extend into the intervening
cartilage, which goes on growing at the
same time ; and it appears that in the
part of the shaft already ossified little or no
elongation takes place by interstitial growth.
This is shown by an experiment first made
by Dr. Hales and afterwards by Duhamel
and by John Hunter, in which, two or more
holes being bored in the growing bone of a
young animal at a certain measured distance
from each other, they are found after a time
not to be farther asunder, although the
bone has in the mean while considerably
increased in length.* In like manner the
shaft also increases in circumference by
deposition of new bone on its external sur-
face, while at the same time its medullary
canal is enlarged by absorption from within.
A ring of silver or platinum put round the
wing-bone of a growing pigeon, becomes
covered with new bone from without,
and the original bone included within it
gets thinner, or, according to Duhamel,
who first made the experiment, is entirely
removed, so that the ring comes to lie
within the enlarged medullary canal.
Madder given to an animal along with its
food, tinges the earth of bone, which, acting as a
sort of mordant, unites with and fixes the colour-
ing matter. Now, that part of the bone which
is most recently formed, and especially that part
which is actually deposited during the admi-
nistration of the madder, is tinged both more
speedily and more deeply than the older part;
and, as in this way the new osseous growth
can be readily distinguished from the old, ad-
Fig. LYIII. SUBPERIOSTEAL
LAYER PROM THE EXTREMITY
OF THE BONY SHAFT OF THE
OSSIFYING TIBIA, AS DESCRIBED
IN THE TEXT.
The cartilage and more open
bony tissue have been scraped off
from the inside of the crust, ex-
cept at a, where a dark shade
indicates a few vertical osseous
areolae out of focus and indistinctly
seen. The part a, b, of the crust
is ossified, and of granular aspect ;
between 6 and c are the clear reti-
culated fibres into which the earthy
deposit is advancing. Magnified
150 diameters.
vantage was taken of the fact by Duhamel,
and afterwards by Hunter, in their inquiries as to the manner in which bones
increase in size. By their experiments it was shown that when madder is given
to a young pig for some weeks, the external part of its bones is deeply red-
dened, proving that the new osseous matter is laid on at the surface of that previously
formed. Again, it was found that, when the madder was discontinued for some time
before the animal was killed, an exterior white stratum (the last formed) appeared
above the red one, whilst the internal white part, which was situated within the red,
* Hales, Veget. Statics., 4th edit. p. 340 ; Duhamel, Mem. de 1'Acad. des Sc., 1743 et
seq. Hunter (reported by Home) in Trans, of Soc. for Imp. of Med. and Chir. Know-
ledge, vol. ii. ; also Catalogue of Hunterian Museum, vol. i. p. 249. Duhamel Avas led
from some of his experiments to infer that an interstitial elongation took place near the
ends ; but there is some doubt left as to the precise circumstances of the experiments
in these cases. Both Hales and Duhamel, in experimenting on the growing tibia of a
chicken, observed that the addition of new bone was much greater at the upper end. Dr.
Humphry has found that in the femur the elongation is greater at the lower t and in the
humerus at the upper end of the shaft (Med. Chir. Trans, vol. xliv.).
h
cxiv BONE.
and had been formed before any madder was given, had become much thinner;
showing that absorption takes place from within. In this last modification of the
experiment also, as noted by Mr. Hunter, a transverse red mark is observed near the
ends of the bone, beyond which they are white ; the red part indicating the growth
in length during the use of the madder, and the white beyond, that which has taken
place subsequently, thus showing that the increase in length is caused by the
addition of new matter to the extremities.* But other changes take place in the
bone. The spaces in the cancellated structure become enlarged, as well as the
medullary canal, by absorption ; whilst in other parts the tissue becomes more com-
pact by farther deposit on the inner surface of the vascular cavities. The sides of the
shaft in particular acquire greater solidity by the narrowing of the Haversian canals,
within which the vascular membrane continues to deposit fresh layers of bone ; and
madder administered while this process is going on, colours the interior and recently-
formed laminae, so that in a cross section the Haversian apertures appear surrounded
with a red ring. Lastly, Tomes and De Morgan have shown that in bones which
have acquired their full size, a production of new systems of Haversian lamellae con-
tinues throughout life, as described at page xciii.
From the foregoing account it is evident that a great portion of a long bone is
formed independently of cartilage. Those physiologists, therefore, appear to have
reason on their side, who consider the pre-existence of that tissue as not being a
necessary condition of the ossific process, and who regard the precursory cartilage of
the foetal skeleton in the light of a temporary substitute for bone, and also as
affording as it were a mould of definite v figure and of soft but yet sufficiently con-
sistent material in which the osseous tissue may be at first deposited and assume a
suitable form. In fact the cartilage-cells are not ossified, and, as to the slender walls
of the primary areolae formed by calcification of the intercellular cartilaginous
matrix, most of them are, in a long bone, swept away by absorption, in the excavation
of the medullary canal ; so that they can only remain coated, however, and obscured
by secondary laminated deposit in the cancellar structure of bones which begin to
ossify in cartilage, t
The time of commencement of ossification in the different bones, as well as the
number and mode of conjunction of their bony nuclei, are subjects that belong to
special anatomy. It may, however, be here remarked in general, that the commence-
ment of ossification does not in all cases follow the order in which the bones appear
in their soft or cartilaginous state. The vertebrae, for instance, appear as cartilages
before there is any trace of the clavicle, yet 'ossification begins in the latter sooner
than in any other bone of the skeleton. The time when it commences in the clavicle,
and consequently the date of the first ossification in the skeleton, is referred by some
to the seventh week of intra-uterine life ; others assign a considerably earlier period ;
but owing to the uncertainty that prevails as to the age of early embryos, the dates
of commencing ossification in the earliest bones cannot be given with precision.
In regard to the number and arrangement of the nuclei, the following general facts
may be stated : 1. In the long bones there is one centre of ossification in the middle,
and the ends are for the most part ossified from separate nuclei ; whilst a layer of
cartilage remains interposed until the bone has nearly attained its full length. By
this means the bone is indurated in the parts where strength is most required, whilst
its longitudinal growth is facilitated. 2. The larger foramina and cavities of the
* M. Flourens has repeated and varied these experiments, and represented the results
in beautiful delineations. Eecherches sur le Developpement des Os et des Dents. Paris,
1842.
t Nesbitt, in 1736, maintained that the cartilage is "entirely destroyed;" he there-
fore considered it to be a mere temporary substitute ; but the steps of the process of
intracartilaginous ossification as now traced with the aid of the microscope were un-
known to him. The view stated in the text, together with most of the facts adduced in
support of it, was published in the fifth edition of this work in 1846, but, notwith-
standing the comprehensive researches of Bruch, by which he was led to the same opinion
(Denks. d. Schweitz. naturf. Gesells. 1852), it met with little notice, and probably less
assent, until the subject was treated of in a special memoir by the late H. Miiller (Zeits.
fur wissensch. Zool. vol. ix., 1858), Jx> whom the doctrine in its modern shape is now
commonly ascribed.
MUSCULAR TISSUE. cxv
skeleton are for the most part formed by the junction of two, but more generally of
three or more nuclei round the aperture or included space. The vertebral rings, the
acetabulum, the occipital foramen, and the cranium itself, are illustrations of this.
It is easy to conceive that in this way the ready and equable enlargement of such
cavities and apertures is provided for. 3. Bones of a complex figure, like the ver-
tebrae, have usually many nuclei; but the converse is not always true. 4. We can
frequently connect the number of nuclei with the principle of uniformity of type on
which the skeleton of vertebrated animals is constructed. Thus the typical form of
the sternum seems to be that of a series of distinct bones, one placed between each
pair of ribs in front, as the vertebrae are behind, and this is its permanent condition
in many quadrupeds. In man it conforms to the archetype in its mode of formation,
in so far as it is ossified from several centres, and for some time consists of several
pieces ; but, to suit the fabric of the human thorax, these at last coalesce one with
another, and are reduced in number to three.
In the reunion of fractured bones, osseous matter is formed between and around
the broken ends, connecting them firmly together ; and when a portion of bone dies,
as happens in necrosis, a growth of new bone very generally takes place to a greater
or less extent, and the dead part is thrown off. The several steps of the process of
restoration in these instances are so fully described in works on Surgical Pathology,
that it is unnecessary to add to the length of this chapter by introducing an account
of them here.
MUSCULAR TISSUE.
The muscular tissue is that by means of which the active movements of
the body are produced. It consists of fine fibres, which are for the most
part collected into distinct organs called muscles, and in this form it is
familiarly known as the flesh of animals. These fibres are also disposed
round the sides of cavities and between the coats of hollow viscera, forming
strata of greater or less thickness. The muscular fibres are endowed with
contractility , a remarkable and characteristic property, by virtue of wliich
they shrink or contract more or less rapidly under the influence of certain
causes which are capable of exciting or calling into play the property in
question, and which are therefore named stimuli. A. large class of muscles,
comprehending those of locomotion, respiration, expression, and some
others, are excited by the stimulus of the will, or volition, acting on them
through the nerves ; these are therefore named " voluntary muscles,"
although some of them habitually, and all occasionally, act also in obe-
dience to other stimuli. There are other muscles or muscular fibres which
are entirely withdrawn from the control of the will, such as those of the
heart and intestinal canal, and these are accordingly named " involuntary."
These two classes of muscles differ not only in the mode in which they
are excited to act, but also to a certain extent in their anatomical charac-
ters ; and on this account we shall consider the structure of each class
separately.
Of the structure of voluntary muscles. The voluntary muscular fibres
are for the most part gathered into distinct masses or muscles of various
sizes and shapes, but most generally of an oblong form, and furnished with
tendons at each extremity, by which they are fixed to the bones.
The two attached extremities of a muscle are named, in anatomical de-
scriptions, its origin and insertion ; the former term being usually applied
to the attachment which is considered to be most fixed, although the rule
cannot be always applied strictly. The fleshy part is named the belly,
which in some cases is interrupted in the middle or divided into two by
a tendon, and then the muscle is said to be biventral or digastric ; on
MUSCULAR TISSUE.
the other hand it may be cleft at one end into two cr three portions, in
which case it is named bicipital or tricipital.
Fig. LIX. Fig. LX.
Fig. LTX. A, SMALL PORTION OP MUSCLE, NATURAL SIZE ; B, THE SAME MAGNIFIED
5 DIAMETERS, CONSISTING OF LARGER AND SMALLER FASCICULI, SEEN IN A TRANSVERSE
SECTION.
Fig. LX. A FEW MUSCULAR FIBRES, BEING PART OP A SMALL FASCICULUS, HIGHLY
MAGNIFIED, SHOWING THE TRANSVERSE SlRI^!.
a, end view of b, b, fibres ; c, a fibre split into its fibrils.
The muscular fibres are collected into packets or bundles, of greater or
less thickness, named fasciculi or lacerti (fig. LIX.), and the fibres themselves
consist of much finer threads, visible by the aid of the microscope, which
are termed muscular filaments, fibrillse or fibrils (fig LX., c). The fibrils
run parallel with each other in the fibres, and the fibres are parallel in the
fasciculi ; and the fasciculi extend continuously from one terminal tendon to
the other, unless in those instances, like the rectus muscle of the abdomen
and the digastric of the inferior maxilla, in which the fleshy part is inter-
rupted by interposed tendinous tissue. The fasciculi also very generally
run parallel, and, although in many instances they converge towards their
tendinous attachment with various degrees of inclination, yet in the volun-
tary muscles they do not interlace with one another.
Shtath. An outward investment or sheath of areolar tissue (sometimes
named perimysium) surrounds the entire muscle, and sends partitions in-
wards between the fasciculi ; furnishing to each of them a special sheath.
The areolar tissue extends also between the fibres, but does not afford to
each a continuous investment, and therefore cannot be said to form sheaths
for them. Every fibre, it is true, has a tubular sheath ; but this, as will
be afterwards explained, is not derived from the areolar tissue. The tissue
of the sheath is composed of elastic (yellow) as well as of white fibres ; but
the elastic element is found principally in its investing (as distinguished
from its penetrating) portion. The chief uses of the areolar tissue are to
connect the fibres and fasciculi together, and to conduct and support the
bloodvessels and nerves in their ramifications between these parts. The
relation of these different subdivisions of a muscle to each other, as well
as the shape of the fasciculi and fibres, is well shown by a transverse
section (figs. LIX. and LX.).
FASCICULI.
Fasciculi, The fasciculi are of a prismatic figure, and their sections have
therefore an angular outline. The number of fibres of which they consist
varies, so that they differ in thickness, and a large fasciculus may be divisible
into two or three orders of successively smaller bundles, but of no regularly
diminishing magnitude. Some muscles have large, others only small fasci-
culi ; and the coarse or fine texture of a muscle, as recogtrized by the
dissector, depends on this circumstance. The length of the fasciculi is not
always proportioned to the length of the muscle, but depends on the arrange-
ment of the tendons to which their extremities are attached. When the
tendons are limited to the ends of a long muscle, as in the sartorius, the
fasciculi, having to pass from one extremity to the other, are of great length ;
but a long muscle may be made up of a series of short fasciculi attached
obliquely to one or both sides of a tendon, which advances some way upon
the surface or into the midst of the fleshy part, as in the instances of the
rectus muscle of the thigh, and the tibialis posticus. Muscles of the kind
last referred to are named " penniform," from their resemblance to the
plume of a feather, and other modifications of the arrangement, which can
be readily conceived, are named " semi-pen niform " and ''compound penni-
form." Many short fasciculi connected thus to a long tendon, produce by
their combined operation a more powerful effect than a few fasciculi running
nearly the whole length of the muscle ; but by the latter arrangement the
extent of motion is greater, for the points of attachment are moved through
a longer space.
Fibres ; their figure and measurement. In shape the fibres are cylindrical,
or prismatic, and in the latter case often with some rounded surfaces and
angles. Their size is tolerably uniform, although fibres occur here aud there
in a muscle which differ greatly in size from the prevailing standard. Mr.
Bowman gave the average diameter in the male at -g-j-g- and in the female
at T ^ of an inch. According to later measurements by Kolliker in
different regions of the body, the prevailing size of the fibres in the muscles
of the trunk and limbs is from T ^ to -oo f an inch, but is less in
those of the head, especially in the facial muscles, in which he found the
diameter to range from T i^y down to -^-^Q of an inch.
Cross stripes. When viewed by transmitted light with a sufficiently high
power of the microscope, the fibres, which are then clear and pellucid in
aspect, appear marked with fine parallel stripes or bands passing across them
directly or somewhat obliquely with great regularity (figs. LX. and LXI. A).
The stripes are commonly said to be dark, with light intervals ; but it is
probably more correct to speak of both light and dark stripes which alter-
nately cross the fibre. It must, however, be remembered that the substance
of the fibre is quite translucent, and, by changing the focus, the stripes
which at first appeared dark become light, and the previously light ones are
now dark. In what may be considered the definite or true focus, the dark
and light stripes are nearly of equal breadth, and then also may be seen,
very generally but not in all cases, a fine dark line passing along the middle
of the light stripe and dividing it into two (fig. LXI. A). This intermediate
line when closely examined appears to be a row of dark points. About
eight or nine dark and as many light stripes may be counted in the length
of -ro 1 ?)^ f au mcn > which would give about -j-y^^ inch as the breadth
of each. But whilst this may be assigned as their usual breadth, they are
in different parts found to be much narrower, so that not unfrequently they
are double the above number in an equal space. This closer approxima-
tion may generally be noticed in thicker and apparently contracted parts
CXV111
MUSCULAR TISSUE.
Fig. LXI.
of the fibre, but it is by no means confined to such parts. This cross-
striped appearance, which is most beautiful and characteristic, is found in all
the voluntary muscles ; but it is not altogether confined to them, for it is
seen in the fibres of the heart, which is a strictly involuntary organ : striped
fibres are also found in the pharynx and upper part of the gullet, in the
muscles of the internal ear, and those of the urethra, parts which are not
under the direct control of the will.
Structure of the fibres. A muscular fibre may be said to consist of a large
number of extremely fine filaments or fibrils inclosed in a tubular sheath.
This, the proper sheath of the fibre, is named sarcolemma or myolemma.
It consists of transparent and apparently homogeneous membrane agreeing
in chemical characters
with elastic tissue, and,
being comparatively
tough, will sometimes
remain entire when
the included fibrils are
ruptured by stretching
the fibre, as represented
in fig. LXII. In this
way its existence may
be demonstrated ; and
it is especially well
seen in fish and other
animals which have
large fibres, for in
^ese it is thicker and
stronger. It may also
be well shown in fresh
5?
Fig. LXI. A. PORTION OP A MEDIUM-SIZED HUMAN MUS-
CULAR FIBRE, MAGNIFIED NEARLY 800 DIAMETERS.
B, Separated bundles of Fibrils, equally magnified, a, a,
larger, and b, b, smaller collections ; c, still smaller ; d, d,
the smallest which could be detached, possibly representing
a single series of sarcous elements.
muscular fibres from
the frog, by exposing
them to water under
the microscope. The
fluid is imbibed, and
then collects between
the substance of the
fibre and its sheath so
as to separate the mem-
brane and make it
apparent. At the same
time, as regards mam-
malian muscles, it must
be admitted that it is not always easy to bring the sarcolemma distinctly
into view.
Fibrils. Lines and fissures are sometimes seen running lengthwise in the
substance of the fibres, and indicating their fibrillar structure, as in somo
of those represented in fig. LX. ; and when those longitudinal lines are well
marked, the transverse striae are comparatively indistinct. In a thin trans-
verse section the ends of the fibrils may be seen, when highly magnified, as
small dots or points, which occupy the whole sectional area of the fibre,
showing plainly that the latter is not hollow, as has sometimes been main-
tained, but possesses the same fibrillar structure throughout its whole thick-
ness. The fibrils are closely connected together in the fibre by an inter-
MUSCULAR FIBRES. cxix
mediate pellucid substance in very sparing quantity ; they may be partially
separated and spread out by breaking across a fibre, and gently bruising
the broken end, as at c (fig. LX.), or by splitting up its substance with
fine needles ; and the separation is facilitated by previous immersion of the
muscle for some time in alcohol or in
a weak solution of chronic acid, p-
which either strengthens the fibrils,
or, by acting on the uniting substance,
weakens their lateral cohesion. But
whilst in this way the fibrillar struc-
ture is made apparent, and the fibre
may be split up into fine bundles or
skeins of fibrils (fig. LXI. B), and
threads apparently single may be
detached, yet it is by no means easy to say when we thus arrive at an
insulated ultimate fibril. A thread so separated (fig. LXI. B, c) when viewed
iu proper focus with a magnifying power of 400 or 600, appears to consist
of a row of dark quadrangular particles, named sarcous elements by Mr. Bow-
man, with bright intervals between them, as if they were connected by some
pellucid substance of less refractive power. For the most part also a dark
line may be discovered passing across the middle of each bright space. I
am disposed, however, to think that the filaments thus described consist of
more than one ultimate fibril ; for I have now and then seen in specimens of
human muscle treated with chronic acid, a finer filament (as at d, fig. LXT.)
lying alongside one or more of those above described, and, whether itself an
ultimate fibril or not, showing at least that those with the quadrangular
particles are composite. In such a fine fibril the dark sarcous elements,
whilst agreeing in length with those alongside, are slender, rod-shaped, or
linear in figure ; and in the middle of the bright intervals between them
there is a dark point. In short, the fibril looks like a line regularly broken
at short distances, with a clot in each of the breaks. From this it may be
inferred that the greater breadth of the quadrangular particles is caused by
the lateral apposition of several rod-shaped particles ; and it is plain that
the appearance of a dark line in the bright interval is produced by a
transverse range of the intervening dots.
This account corresponds very much with what is seen on a larger scale in the mus-
cular fibres of insects, by which I do not mean the fine, naturally separated, fibres of
the thoracic muscles, sometimes taken for fibrils, but the larger fibres, in which fibrils
answering to the above description are readily separable. In these, the rather long
rod-shaped sarcous elements, of which the fibrils consist, give a fluted character to
the broad cross stripes or bands which, by mutual apposition, they produce in the
fibre (fig. LXIII).
The intermediate dotted line was long since noticed by Busk and Huxley, and was
considered by them to be produced, most probably, by the interposition of a row of
minute sarcous elements ; but, as they justly observe, it is not invariably present.
Cause of the stripes, and cleavage into disks. When the fibrillse lie undis-
turbed in the fibre, the elementary particles of collateral fibrils are situated
in the same transverse plane, and it is to this lateral coaptation of the
particles that the transverse striping of the fibre is due. (See fig. LXTV.)
Accordingly, the cross stripes are not confined to the surface of the fibre,
but may be seen throughout its entire thickness on successively deepening
the focus of the microsdope. The fibres, moreover, when treated with
certain reagents (such as very dilute hydrochloric acid), show a tendency to
2
MUSCULAR TISSUE.
cleave across in a direction parallel to these stripes, and even break up into
tranverse plates or disks, which are formed by the lateral cohesion of the
particles of adjacent fibrils. To make up such a disk, therefore, every fibril
contributes a particle, which separates from those of its own fibril, but co-
heres with its neigh-
Fig. LXIII. bour on each side,
and this with per-
fect regularity. In*
deed, Mr. Bowman
conceives that the
subdivision of a fibre
into fibrillae is
merely a phenome-
non of the same
kind, only of more
common occurrence,
the cleavage in the
latter case taking
place longitudinally
instead of trans-
Fig. LXIV.
Fig. LXIII.
MUSCULAR
A. PORTION OF A (RATHER SMALL SIZED)
FIBRE, PROM A WATER BEETLE, MAGNIFIED
imimiiiiiiii
limimiimii
iiimmmiiii
ijiiiiiiiiiiiii
ijiiiiiiiuiml
iiiiiiiiiiiiiii
730 DIAMETERS.
rt, a, dark cross bands formed by the apposition of slender
rod-shaped sarcous elements ; b, b, light stripes with inter-
mediate line of dark specks; at a' , of, inclined position of rods,
as here and there seen. B, a detached bundle of fibrils
equally magnified. On one side an apparently single series of
elongated sarcous elements, with intermediate dots, possibly a
single fibril.
Fig. LXIV. DIAGRAM
TO SHOW HOW THK
STRIPES OF MUSCU-
LAR FIBRE ARE PRO-
DUCED.
versely : according-
ly, he considers that
the fibrillse have no
existence as such in the fibre, any more than the disks ; but that both the
one and the other owe their origin to the regular arrangement of the
particles of the fibre longitudinally and transversely, whereby, on the appli-
cation of a severing force, it cleaves in the one or in the other direction into
regular segments.
While some consider that the fibrils are composed throughout of the same substance,
and that the alternation of dark and light portions is due to unimportant modifica-
tions of it, others believe that the light and dark parts differ essentially in nature.
In proof of this Briicke adduces observations to show that the dark parts, or sarcous
elements, doubly refract the light (or are " anisotropic "), whilst the intermediate
light substance is singly refractive (" isotropic"). Moreover, as the sarcous elements
and the dark stripes formed by them are variable in size and position the stripes
being sometimes broad and widely apart, at other times narrow and closer together
Briicke infers that the dark, doubly refracting, or anisotropic substance consists of an
aggregation of undistinguishably minute, doubly refracting molecules, named by him
disdiaclasts, imbedded in the isotropic matter; which, by grouping together in
various numbers and modes, give rise to the variations in the size, figure, and arrange-
ment of the sarcous elements. In reference to this view I may observe that, while it
MUSCULAR FIBRES.
cxxi
is easy to see that the muscular fibres are doubly refractive, and while the light and
dark parts most probably differ in certain physical and chemical properties, it is not
so clearly made out that the doubly refracting property is confined to the one of them.
LXV.
Nuclei, or muscle-corpuscles. A number of pale, finely granular, oval
corpuscles, resembling cell-nuclei, are found in the fibres. In mammalian
muscles they lie upon the inner surface of the sarcolemma, but in frogs they
are distributed through the substance of the fibre (fig. LXV.). These have
been supposed to be connected with the
growth and nutrition of the muscle. They
are obvious in the foetus some time before
birth, but afterwards the addition of acetic
acid is usually required in order to render
them visible. They are probably nuclei per-
taining to the elongated cells in which the
substance of the fibres is originally de-
veloped ; and a small amount of granular
matter which is not uncommonly collected
around them has been regarded as a remnant
of the formative protoplasm. Other cor-
puscles, mostly fusiform, but varying in
shape, and having the character of con-
nective tissue corpuscles, lie here and there
outside the sarcolemma, and doubtless be-
long to the interposed connective tissue.
Interstitial granules. Different obser-
vers, and especially Kolliker, have described
fine granules disposed in rows between the
fibrils or smaller bundles of fibrils, as of
frequent occurrence in the muscular fibres
of man and animals (fig. LXVL). They
have been especially noted in the heart,
and although they do not naturally show the characters of fat, it has been
presumed that they may by conversion give rise to the fatty degeneration
of muscular tissue. I must confess that I have not been able to perceive
these granules in healthy human voluntary muscle.
Length and ending of the fibres. The fibres composing a muscle are of
limited length, not exceeding one inch and a half ; and accordingly in a long
fasciculus a fibre does not reach from one tendinous attachment to the other,
but ends with a tapering pointed extremity, invested with its sarcolemma,
and cohering with neighbouring fibres. Unless when either is fixed to a
tendon, both extremities of the fibre terminate in the way described, so
that it has a long fusiform shape.
Branched fibres. Generally speaking, the fibres neither divide nor anas-
tomose ; but this rule is not without exception. Branched and anastomosing
fibres are common in the heart (fig. LXXII.) ; in the tongue of the frog the
muscular fibres (fig. LXVII. ) as they approach the surface divide into
numerous but not anastomosing branches, by which they are attached to the
under surface of the mucous membrane. The same thing has also been
seen in the tongue of man and many other animals ; and the fibres of the
facial muscles of mammals have been shown by Busk and Huxley to divide
in a similar manner where they fix themselves to the skin.
Connection with tendons. According to Professor Kolliker, the mode of
Fig. LXV. A FROG'S MUSCULAR
FIBRE TREATED WITH ACETIC
ACID, MAGNIFIED 350 DIAM.
(from Kolliker).
The nuclei are somewhat shrunk.
Interstitial granules in longitudinal
rows, here and there, but these are
mostly indistinct from compression,
and appear as mere lines.
cxxii
MUSCULAR TISSUE.
connection differs when the muscular fibres are continuous in a direct line
with those of the tendon from that which is observed when the former join
the latter at a more or less acute angle. In the first case, the two are
directly continuous, the muscular fibre being distinguishable from that of
the fibrous tissue by its striation alone. In the second case, the muscular
fibres terminate in conical processes, which are received in corresponding
Fig. LXVI.
Fig. LXVII.
Fig. LXVI. FROG'S MUSCULAR FIBRE, SHOWING INTERSTITIAL GRANULES, MAGNIFIED
350 DIAM. (from Kolliker).
Fig. LXYII. A BRANCHED MUSCULAR FIBRE FROM THE FROG'S TONGUE, MAGNIFIED
350 DIAM. (from Kolliker).
depressions of the tendinous structure, to which they cling ; the connective
tissue of the one being continuous with that of the other. Weismann, who
adopts this view on later observations of his own, states that the sarco-
lemma surrounds the ends of the fibres, which are not continuous with but
rather, as it were, cemented to the tendon. Mr. Ellis, on the other hand,
describes the connection of striated muscle with tendon as taking place in
all cases in the following manner. When a muscular fibre is about to end
in a tendon, its component fibrils are collected into bundles of different
lengths and sizes like the roots of a tree. Around each bundle tendinous
tissue is collected, forming a sheath which appears gradually to cease as it is
continued backwards on the undivided fibre. The muscular fibrils of a
bundle in approaching the tendon gradually cease, each having probably its
own tendinous thread to fix it. The central bundles of fibrils reach further
than the circumferential, and thus, when the latter are broken off by
attempts made to detach a fibre from its neighbours, the fibre appears to
have a pointed ending. In this case also Weismann maintains that the
sarcolemina intervenes between the muscular substance and the tendon.
VESSELS OF MUSCLE.
cxxiii
Mr. Ellis dees not confirm Professor Kolliker's account of the oblique
mode of attachment. He states that, iu such instances as the gastro-
cnemius and soleus, every fibre is provided with its separate tendon and is
continuous with it as above described, and that the increasing thickness of
the main tendon from above downwards is due to successive additions, in
the form of strata, of the contributing tendons from the lower placed layers of
muscular fibres ; and this explanation is supported by subsequent obser-
vations of Fick, Margo, and Frey. In attaching themselves to the skin
and mucous membranes, the muscular fibres, according to the careful descrip-
tion of Dr. Salter, divide into pointed processes or fine filaments which are
continuous with those of the connective tissue.
Blood-vessels. The blood-vessels of the muscular tissue are extremely
abundant, so that, when they are successfully filled with coloured injection,
the fleshy part of the muscle contrasts strongly with its tendons. The
arteries, accompanied by their
Fig. LXVIII.
Fig. LXVIII. CAPILLARY VESSELS OF MUSCLE,
FROM AN INJECTION BY LIEBERKUHN, SEEN
WITH A LOW MAGNIFYING POWER.
The specimen was preserved in spirits ; when
the muscle is dried, the vessels appear much
closer.
associate veins, enter the muscle
at various points, and divide
into branches ; these pass
among the fasciculi, crossing
over them, and dividing more
and more as they get between
the finer divisions of the mus-
cle ; at length, penetrating the
smallest fasciculi, they end in
capillary vessels which run be-
tween the fibres. The vessels
are supported in their progress
by the subdivisions of the
sheath of the muscle, to which
also they supply capillaries.
The capillaries destined for the
proper tissue of the muscle are extremely small (fig. LXVIII.), they form
among the fibres a fine network, with narrow oblong meshes, which are
stretched out in the direction of the fibres : in other words, they consist
of longitudinal and transverse vessels, the former running parallel with the
muscular fibres, and lying in the angular intervals between them, the
latter, which are much shorter, crossing between the longitudinal ones, and
passing over or under the intervening fibres.
None of the capillary vessels enter the sarcolemma or proper sheath of the fibre,
and the nutritious fluid which they convey must therefore reach the finer elements of
the muscle by imbibition. Moreover, as the capillaries do not penetrate the fibres,
but lie between them, their number in a given space, or their degree of closeness, will
in some measure be regulated by the number and consequently by the size of the
fibres ; and accordingly in the muscles of different animals it is found that, when the
fibres are small, the vessels are numerous and form a close network, and vice versd :
in other words, the smaller the fibres, the greater is the quantity of blood supplied to
the same bulk of muscle. In conformity with this, we see that in birds and mam-
malia, in which the process of nutrition is active, and where the rapid change
requires a copious supply of material, the muscular fibres are much smaller and
the vessels more numerous than in cold-blooded animals, in which the opposite con-
ditions prevail.
Lymphatics. Of lymphatic vessels in the muscular tissue nothing certain
is known. From an examination of the lymphatics which appear to proceed
cxxiv MUSCULAR TISSUE.
from different muscles, Kolliker infers that small muscles are destitute of
such vessels, and that the few which apparently issue from some of the
larger muscles, belong to the sheath and its larger subdivisions, and not to
the proper muscular tissue.
Nerves. The nerves of a voluntary muscle are of considerable size.
Their branches pass between the fasciculi, and repeatedly unite with each
other in form of a plexus, which is for the most part confined to a small
part of the length of the muscle or muscular division in which it lies.
From one or more of such primary plexuses, nervous twigs proceed and
form finer plexuses composed of slender bundles, each containing not more
than two or three dark-bordered nerve-fibres, whence single fibres pass off
between the muscular fibres and divide into branches which are finally dis-
tributed to the tissue. The mode of final distribution will be described
with the general anatomy of the nerves.
Nerves of small size accompany the branches of blood-vessels within
muscles, but do not reach the capillaries ; though destined for the vessels,
these nerves sometimes communicate with the proper muscular plexuses.
Involuntary muscles. The involuntary muscular tissue differs from the
voluntary kind, not only in its want of subjection to the will, but also in
its external characters ; for whilst in many parts it appears in the form of
fibres, these, except in the heart and a few instances of less note, are un-
marked by the cross lines so characteristic of the striped fibres ; moreover,
they are in reality made up of elongated contractile cells cemented together
by some kind of uniting medium.
Plain or unstriped muscular tissue (fig. LXIX.). This is generally of a pale
colour. The fibres are for the most part roundish or prismatic, but are
readily flattened in examination. Some are not above -y^^ of an inch
in diameter ; but the larger measure from -$-5-3-$ to -J^-Q (Ellis). Under
the microscope they have a peculiar soft aspect, without a strongly shaded
border ; and they are marked at short intervals with oblong corpuscles,
which give them a very characteristic appearance, especially after the appli-
cation of acetic acid, which renders the corpuscles much more conspicuous.
The substance of the fibres is translucent, but clouded or finely granular ;
and in the latter case the granules are sometimes arranged in longitudinal
lines. There is no sarcolemma. These fibres, as already said, are made up
of cells, named contractile fibre-cells, which were first distinguished as the
true elements of the tissue by Kolliker. The cells may form fibres, bundles,
and strata, or may be less regularly arranged, or mixed with other tissues
in greater or less proportion. They are of an oblong flattened shape (figs. LXX.
and LXXI), usually pointed at the ends, but sometimes abruptly truncated,
and varying greatly in length according to the part or organ in which they
are found. Some occur which are cleft or forked at one end. They mea-
sure for the most part from ^-l^ to ^-^ of an inch or more in length. Their
substance is finely granular and sometimes faintly striated, and, with few
exceptions, no distinction is visible between envelope and contents. Each
has a nucleus (a, a), rarely more than one, which is always elongated and
either oval or rod-shaped. Accordingly, the nuclei of the fibres above
described belong to the constituent cells. By macerating the tissue in nitric
acid diluted with four times its weight of water, the separation of the cells
is greatly facilitated.
It is proper to state that a different view of the structure of the plain muscular
tissue is entertained by some authorities. Mr. Ellis, after a very extended inquiry,
PLAIN OR UNSTEIPED.
cxxv
has arrived at the conclusion that it consists of fibres, which are not made up of the
cells described, but agree in essential structure with those of voluntary muscle ; and
he considers the so-called nuclei as corpuscles belonging to the investing tissue of the
Fig. LXX.
Fig. LXIX.
Fig. LXIX. PLAIN MUSCULAR
FIBRES PROM THE HUMAN BLAD-
DER, MAGNIFIED 250 DIAMETERS.
A, in their natural state ; B,
treated with acetic acid to show the
corpuscles.
Fig. LXXI.
Fig. LXXI. MUSCULAR FIBRE-
CELLS PROM HUMAN ARTERIES,
MAGNIFIED 350 DIAMETERS (K6l-
liker).
a, natural state; b, treated with
acetic acid.
Fig. LXX. MUSCULAR FIBRE-CELL FROM THE MUSCULAR COAT OF THE SMALL INTESTINE,
MAGNIFIED (Kolliker).
muscular fibres. "Without denying that there may be a modification or variety of the
non-striated muscular fibres not divisible into singly nucleated cells, I nevertheless
think that the existence of such contractile cells must now be admitted as fully es-
tablished, and that the fibres and bundles of the plain muscular tissue are commonly
made up of these cells.
The plain muscular tissue is for the most part disposed between the coats
of the membranous viscera, as the stomach, intestines, and bladder, in the
parietes of the air-tubes, excretory ducts of glands, and the like. It is
generally collected into larger and smaller fasciculi, which in many cases
cross one another and interlace. The fasciculi are connected at their ends
with tendinous tissue, and are thus inserted into the membranous and
MUSCULAR TISSUE.
Fig. LXXII.
firmer parts in the neighbourhood. Small tendons are also fixed by blending
with the fibrous sheaths investing contiguous muscular bundles. In the
gullet, Mr. Ellis has found that the longitudinal muscular fasciculi are inter-
sected wholly or partially, at intervals of from ^V to -J^ of an inch, by
small tendons into which they are inserted, after the fashion of the rectus
abdomiiiis, only on a miniature scale, and he thinks it probable that this
disposition may exist in other parts.
The plain muscular tissue is met with iu the lower half of the gullet, the
stomach, and the whole intestinal canal ; that is, both in the muscular coat
of the alimentary canal, and also as a layer in the tissue of the mucous
membrane, and in the villi ; in the trachea and bronchial tubes, in the
bladder and ureters and the ducts of the larger glands generally, in the
uterus and its appendages, in the corpora caveruosa of both sexes, in the
prostate gland, and in the ciliary muscle and iris. The middle coat of the
arteries, the coats of many veins and the larger lym-
phatics contain plain muscular tissue. It has also been
detected in certain parts of the skin, in the dartos or
subcutaneous tissue of the scrotum, and in form of
minute muscles attached to the hair-follicles.
Muscular tissue of the heart. The fibres of the heart
differ remarkably from those of involuntary muscular
organs in general, inasmuch as they present transverse
strise. The striae, however, are less strongly marked,
and less regular, and the fibres are smaller in diameter
than in the voluntary muscles. Many of the fibres are
attached to the tendinous structure connected with the
orifices and valves, and as has been already stated, they
are seen to divide and anastomose (fig. LXXII). The
tissue of the heart differs also from most other involun-
tary muscular structures by its deep colour, but it
agrees with them in the interlacement of its fasciculi.
Development of muscle. The form-elements of the
plain or uii striped muscular tissue are derived from
embryonic nucleated cells, consisting of granular proto-
plasmic substance, as usual. These become lengthened
out, pointed at the ends, and flattened, with elongation
of the nucleus, whilst their substance becomes more uniform in aspect, and
acquires its permanent condition and characteristic properties.
The striated muscular tissue is also developed in the embryo from cells.
Schwann considered each fibre to be formed by the linear coalescence of
several cells ; and this opinion is still maintained by some authorities.
Recent researches, however, for the most part, tend to establish the view
originally, I believe, promulgated by Reinak, viz., that the fibres are pro-
duced by the elongation of single cells, with differentiation of their contents
and multiplication of their nuclei ; and Dr. Wilson Fox, who has quite lately
investigated the process in the tadpole, the chick, and the mammalian
embryo, at very early stages, has arrived at the same conclusion.* Dr. Fox
finds that the first elements of the muscular fibres are rounded or oval cells,
with a clear nucleus and granular contents, agreeing in all respects with the
cells of which the parts of the embryo body originally consist. To form a
muscular fibre, a cell elongates, often with pointed ends ; the nucleus
Fig. LXXII. MUS-
CULAR FIBRES
FROM THE HEART,
MAGNIFIED, SHOW-
ING THEIR CROSS
STRI.E, DIVISIONS,
AND JUNCTIONS
(from Kolliker).
Phil. Trans. 1866, p. 101.
DEVELOPMENT AND GROWTH.
generally divides into two, and by further division these are multiplied ; a
fine membrane, at first absent or invisible, is soon discovered, bounding the
cell and inclosing its contents. In the mean time the substance becomes
striated longitudinally at one fart, and more transparent, the granules dis-
appearing. The striatiori, which is the first indication
of the proper muscular substance, extends throughout pig. LXXIII.
the length of the elongated cell, but at first affects
only a small part of its breadth, and the remaining
space is occupied by unchanged granular matter and
the nucleus or nuclei which lie on one side. In due
time, however, this conversion into the proper muscular
substance, further shown by the appearance of cross
strise, proceeds through the whole thickness of the cell,
or fibre as it may now be called ; the inclosing cell-
membrane becomes the sarcolemma, and the nuclei,
with a small residue of the granular protoplasm still
adhering to them, remain.
Growth of muscles. The muscular fibres of the growing
foetus, after having acquired their characteristic form
and structure, continue to increase in size till the time
of birth, and thenceforward up to adult age. In a full
grown foetus most of them measure twice, and some of
them three or four times their size at the middle of foetal
life ; and in the adult they are about five times as large
as at birth. This increase in bulk of the individual
fibres would, of course, so far account for the con-
comitant enlargement of the entire muscles. But there
would seem to be also a multiplication of the fibres ;
and Budge believes he has proved this as regards the
muscles of frogs. Two modes of production of new
fibres have been described viz. first, from connective
tissue corpuscles lying between the existing fibres, by a
process analogous to the original development of the
muscle (von V/ittich) ; secondly, by the splitting up
of a fibre through its whole length into two or more
smaller ones, preceded by multiplication of its included
nuclei. This second process has been observed by
Weismann and by Kolliker in frogs, in the winter
season, and appears to serve for the replacement of fibres
destroyed by fatty degeneration, which is said to be
not uncommon in these creatures. Dr. Beale, however,
denies that the new and slender fibres are derived from
an old and larger one by splitting of its substance ; he
believes that they are produced from cells, as in the first
mode, and that the old fibre is removed. The great
increase in the muscular tissue of the uterus during
gestation takes place both by elongation and thickening
of the pre-existing fibre-cells of which that non- striated
tissue consists, and by the development of new muscular
fibre- cells from small, nucleated, granular cells lying in
the tissue. In the shrinking of the uterus after parturition the fibre-cells
also shrink to their previous size ; many of them become filled with fat-granules
(fig. LXXIII.), and many are doubtless removed by absorption.
Fig. LXXIII.
MUSCULAR FIBRE-
CELLS FKOM THK
UTERUS, THREE
WEEKS AFTER DE-
LIVERY. THE UP-
PER FOUR TREATED
WITH ACETIC ACID,
MAGNIFIED 350
DIAMETERS (from
Kolliker).
a, nuclei ; 7, fat-
granules.
cxxviii MUSCULAR TISSUE.
As far as can be concluded from the observations and experiments that
have hitherto been made on the subject, the striated muscular tissue is not
regenerated in warm-blooded animals. It is true that, when a muscle is cut
across, or a portion removed, the breach will heal, but the loss of substance
is not repaired by new-formed muscular tissue. Striated muscular fibres
have been found in certain tumours of the ovary and testicle, but these
cases are altogether peculiar and abnormal.
Chemical composition of muscle. Muscular tissue contains nearly 80 per
cent, of water, so that in being dried it loses about four-fifths of its weight.
The chief and characteristic constituent of the fibre is an albuminoid body.
This was at one time regarded as fibrin ; but, as it was afterwards shown to
be not identical with that substance, it was distinguished by the name of
syntonin ; the grounds of distinction being, that syntonin is soluble in very
dilute hydrochloric acid, and can be extracted from muscle by that solvent ;
also, that its solution is precipitated by neutral salts. More recently, the
subject has been investigated by Kuhne, who maintains that the albuminoid
matter of muscle exists in the fibres in a liquid form during life, but coagu-
lates after death, and thereby gives rise to the cadaveric rigidity which
then invades the muscles. When extracted from fresh and still irritable
frogs' muscles at a temperature of freezing, this substance, which Kuhne
names myosin, is liquid ; but if it be then exposed to the ordinary heat of
the atmosphere it partially coagulates, and the portion then remaining
liquid (the muscle-serum) when heated to 112 F., or less if it be strongly
acid, yields a further coagulum, which Kuhne considers peculiar to muscle ;
and finally, at 167, ordinary coagulated albumen. The primary coagulation
is hastened by the presence of blood, and possibly it may be due to the
mutual reaction of two albuminoids analogous in their operation to the
fibrinogen and fibrinoplastin (or globulin) of the blood (antea, p. xxxviii.).
The coagulum of myosin is soluble in strong solutions of neutral salts, and
accordingly it may thereby be dissolved out of dead and rigid muscles ; but
it loses this property if previously dissolved in dilute hydrochloric acid.
It then, in fact, agrees with the so-called syntonin, which Kiihne regards,
not as an original albuminoid of muscle, but as myosin altered by the
process of extraction. It has been suggested that the ready solution of
muscular fibre in dilute hydrochloric acid may be owing to the presence of
pepsine in minute quantity.
Other organic compounds also exist in muscle, but in very small proportion
in comparison with the albuminoid matter. Most of them probably result
from the process of wear of the original muscular substance. Among
the most notable are, 1. Kreatin and Kreatinine, both of them nitro-
genized and crystalline, the former neutral, the latter (derived from it),
alkaline ; both are also found in the urine. 2. Sarkin or (Hypoxanthin ).
3. Non-nitrogenized substances, viz. : grape sugar ; inosit an unferment-
able sugar from the tissue of the heart ; glycogen, at least in embryos and
young animals. 4. Various organic acids, viz. , lactic, inosinic, butyric, acetic,
formic and uric. 5. Salts, in which potash predominates over soda,
magnesia over lime, and phosphoric acid over chlorine, muscle, in this
respect, resembling blood-corpuscles as contrasted with serum. Lastly, a
variable amount of fat may be extracted from muscle, and also gelatin ;
the latter no doubt from connective tissue ; for it must be remembered that
a piece of muscle subjected to analysis comprehends, along with the proper
muscular fibres, more or less of connective tissue, blood-vessels and nerves.
The account here given of the chemical constitution of muscle applies
CHEMICAL, PHYSICAL AND VITAL PROPERTIES. cxxix
especially to the striped variety, but, so far as is known, it is essentially
the same in the non -striated tissue.
The juice expressed from a muscle after death, and especially after rigidity has set
in, is acid, from the presence of lactic acid ; so that the cut surface of a dead muscle
reddens litmus-paper. On the other hand a perfectly fresh section of muscle in the
living body, or while it retains its irritability, is alkaline or neutral. But, while this
is true of a living muscle in its usual state, it gives a decided acid reaction after it
has been strongly exerted, as, for instance, after tetanic spasm excited by electricity
or by strychnia poisoning. The acid is probably generated by a change in the
saccharine matter of the muscle. Ultimately the tissue in all cases becomes alkaline
from putrefaction and the evolution of ammonia.
Physical properties of muscle. A dead muscle has little strength, and may be
torn asunder by a force of no great amount. A living muscle readily yields to exten-
sion, and shrinks exactly to its original length when the extending force ceases. Its
elasticity is therefore said to be small in degree, but very perfect or complete in opera-
tion. A dead muscle, especially after cadaveric rigidity has come on, resists exten-
sion more powerfully, but does not afterwards return to its original length ; hence
its elasticity is said to be greater than that of the living muscle, but less perfect.
The red colour of muscle is well known, but it differs greatly in degree in different
cases. It is usually paler in the involuntary muscles ; but here the heart again is a
striking exception. In most fish the chief muscles of the body are nearly colourless, and
in the breast of wild fowl we see a difference in the depth of colour in different strata
of the same muscles. The redness is no doubt partly due to blood contained in the
vessels, but not entirely so, for a red colouring matter, apparently of the same nature
as that of the blood, is obviously incorporated with the fibres.
Under this head must also be mentioned the manifestation of electricity by a
quiescent but living muscle. When a muscle taken from a living or recently killed
animal (a frog is commonly used) is brought into connection with the ends of a very
delicate galvanometer, -so that one extremity of the latter touches the outer surface of
the muscle and the other a cross section made through its fibres, the needle will
deviate so as to indicate an electric current passing along the wire from the surface
of the muscle to its cross section. If both ends of the galvanometer touch points in the
length of the muscle equidistant from its middle, no effect ensues, but if one point of
contact be farther than the other from the middle, a current will pass along the wire
from the nearer to the more distant point. The same results are obtained with a
small shred or fasciculus of the muscle. The phenomenon described is called " the
muscular current," and is supposed to indicate a state of electric polarity in the
particles of the muscle, probably caused by chemical changes going on in its
substance.
Vital properties of muscle, The muscular tissue possesses a considerable degree of
sensibility, but its characteristic vital endowment, as already said, is irritability or
contractility, by which it serves as a moving agent in the animal body.
Sensibility. This property is manifested by the pain which is felt when a muscle is
cut, lacerated, or otherwise violently injured, or when it is seized with spasm. Here,
as in other instances, the sensibility belongs, properly speaking, to the nerves which
are distributed through the tissue, and accordingly, when the nerves going to a muscle
are cut, it forthwith becomes insensible. It is by means of this property, which is
sometimes called the "muscular sense," that we become conscious of the existing
state of the muscles which are subject to the will, or rather of the position and
direction of the limbs and other parts which are moved through means of the volun-
tary muscles, and we are thereby guided in directing our voluntary movements towards
the end in view. Accordingly, when this muscular sense is lost, while the power of
motion remains, a case which, though rare, yet sometimes occurs the person cannnot
direct the movements of the affected limbs without the guidance of the eye.
Irritability or Contractility. The merit of distinguishing this property of the
animal body from sensibility on the one hand, and from mere mechanical phenomena
on the other, is due to Dr. Francis Glisson, a celebrated English physician of the
seventeenth century ; but irritability, according to the view which he took of it, was
supposed to give rise to various other phenomena in the animal economy besides
the visible contraction of muscle, and his comprehensive acceptation of the term has
cxxx MUSCULAR TISSUE.
been adopted by many succeeding authorities, especially by writers on pathology.
Haller, in his use of the term irritability, restricted it to the peculiar property of
muscle.
Stimuli. In order to cause contraction, the muscle must be excited by a stimulus.
The stimulus may be applied immediately to the muscular tissue, as when the fibres
are irritated with a sharp point ; or it may be applied to the nerve or nerves which
belong to the muscle : in the former case, the stimulus is said to be " immediate," in
the latter, "remote." The nerve does not contract, but it has the property, when
stimulated, of exciting contractions in the muscular fibres to which it is distributed;
and this property, named the " vis nervosa," is distinguished from contractility,
which is confined to the muscle. Again, a stimulus maybe either directly applied to
the nerve of the muscle, as when that nerve is itself mechanically irritated or galva-
nised ; or it may be first made to act on certain other nerves, by which its influence
is, so to speak, conducted in the first instance to the brain or spinal cord, and then
transferred or reflected to the muscular nerve.
The stimuli to which muscles are obedient are of various kinds ; those best ascer-
tained are the following, viz. : 1. Mechanical irritation of almost any sort, under
which head is to be included sudden extension of the muscular fibres. 2. Chemical
stimuli, as by the application of salt or acrid substances. 3. Electrical ; usually by
means of a galvanic current made to pass through the muscular fibres or along the
nerve. 4. Sudden heat or cold ; these four may be classed together as jthysical
stimuli. Next, mental stimuli, viz. : 1. The operation of the will, or volition. 2.
Emotions, and some other involuntary states of the mind. Lastly, there still remain
exciting causes of muscular motions in the economy, which, although they may pro-
bably turn out to be physical, are as yet of doubtful nature, and these until better
known may perhaps without impropriety be called organic stimuli; to this head
may be also referred, at least provisionally, some of the stimuli which excite convul-
sions and other involuntary motions which occur in disease.
Duration of irritability after death. It is known that, if the supply of nutrient
material be cut off from a muscle by arresting the flow of blood into it, its contrac-
tility will be impaired, and soon extinguished altogether, but will after a time be
recovered again if the supply of blood be restored. The influence of the blood sup-
plied to muscles in maintaining their contractility has been strikingly shown by Dr.
Brown-S6quard, who has succeeded in restoring muscular contractility in the bodies
both of man and animals some time after death, and after it had become to all ap-
pearance extinct, by injecting into the vessels arterial blood deprived of its fibrin,
or defibrinated venous blood previously reddened by exposure to the air. In warm-
blooded animals in which the nutritive process is more active, and the expenditure
of force more rapid, the maintenance of irritability is more closely dependent on the
supply of blood and the influence of oxygen, so that it sooner fails after these are
cut off. In accordance with this statement, it is known that while the muscles of
man and quadrupeds cease to be irritable within a few hours after death, and those
of birds still sooner, the muscular irritability will remain in many reptiles and fishes,
even for days after the extinction of sensation and volition and the final cessation of
the respiration and circulationthat is, after systemic death. A difference of the
same kind is observed among warm-blooded animals in different conditions ; thus
irritability endures longer in new-born animals than in those which have enjoyed
respiration for some time and are more dependent on that function; and, in
like manner, it is very lasting in hybernating animals killed during their winter
sleep.
But the duration of this property differs also in different muscles of the same
animal. From numerous careful observations Uysten concluded that in the human
body its extinction takes place in the following order, viz. : 1, the left ventricle of
the heart ; 2, the intestines and stomach ; 3, the urinary bladder ; 4, the right
ventricle; in these generally within an hour; 5, the gullet; 6, the iris; 7, the
voluntary muscles, a, of the trunk, 6, of the lower and c, the upper extremities ;
8, the left auricle, and, 9, the right auricle of the heart, which last was on this
account styled by Galen the " ultimum moriens." In one case Nysten observed the
right auricle to continue irritable for sixteen hours and a half after death. But it has
been recently found that a voluntary muscle will give signs of a certain degree of
CADAVERIC RIGIDITY. cxxxi
irritability even later than this, if it be struck a smart blow with a blunt edge, such as
the back of a knife, across the direction of the fibres. The contraction then produced
is quite local, and confined to the parts struck. Funke states that he and the brothers
Weber obtained this result in the body of a decapitated criminal twenty -four hours
after death.
The time of duration is affected by the mode of death. Thus the irritability is said
to be almost wholly and immediately extinguished by a fatal stroke of lightning, and
to disappear very speedily in the bodies of persons stifled by noxious vapours, such as
carbonic acid, and especially sulphuretted hydrogen. In like manner certain causes
acting locally on muscles accelerate the extinction of their irritability.
Rigor mortis. The " cadaveric rigidity," or stiffness of the body, which ensues
shortly after death, is a phenomenon depending on the muscles, which become fixed
or set in a rigid state, so as to resist flexion of the joints. The rigidity almost in-
variably begins in the muscles of the lower jaw and neck, then invades those of the
trunk, and afterwards those of the limbs, the arms usually before the legs. After
persisting for a time, it goes off in the same order. It usually comes on within a
few hours after death, rarely later than seven hours. In some cases it has been ob-
served to begin within ten minutes (Sommei'), and in others not till sixteen or
eighteen hours ; and the later its access, the longer is its endurance. The rigidity
comes on latest, attains its greatest intensity, and lasts longest in the bodies of ro-
bust persons, cut off by a rapidly fatal disease, or suddenly perishing by a violent
death ; in such cases it may last six or seven days. On the other hand, it sets in
speedily, is comparatively feeble, and soon goes off in cases where the body has been
much weakened and emaciated by lingering or exhausting diseases ; also in new-
born infants, and in the muscles of animals that have been hunted to death. It seems
thus to be affected bj the previous state of nutrition of the muscles. Destruction of
the nervous centres does not prevent the occurrence of rigidity, nor are the muscles
of paralysed limbs exempted from it, provided their nutrition has not been too deeply
affected. The fibres of stiffened muscles are less translucent than before, but no other
change is discovered by the microscope. They no longer show the muscular electric
current.
The immediate cause of the muscular rigidity is doubtful : some conceive it to be
an effect of vital contraction, the last effort of life as it were; others, with more
probability, ascribe it to a solidification of the tissue caused by chemical changes
occurring after death. Kiihne adduces various arguments, some of them, it must be
admitted, of a cogent character, to show that the stiffening is due to post-mortem
coagulation of the myosine. He thinks that the substance of the fibre is liquid dur-
ing life ; but it is difficult to reconcile his notion of actual fluidity of substance with
some of the most obvious properties of a living muscle. At the same time, it is con-
ceivable that liquid myosin may be present in the interstices of more consistent
elements of the living fibre, and may give rise to rigidity by coagulating after death.
Free lactic acid is developed in the substance of rigid muscle, and some regard it as
the cause of the coagulation of the myosin, but although an acid condition very gene-
rally accompanies rigidity, the concurrence is not invariable or essential. Dr. Brown-
Se"quard, in opposition to the chemical theory, maintained that he could remove
rigidity by injecting blood into the vessels of the muscle; but Kiihne holds this to be
impossible after rigor has decidedly set in. The general accession of rigidity is an
unequivocal sign of death.*
NERVOUS SYSTEM.
OF the functions performed through the agency of the nervous system,
some are entirely corporeal, whilst others involve phenomena of a mental or
psychical nature. In the latter and higher class of such functions are first
to be reckoned those purely intellectual operations, carried on through the
instrumentality of the brain, which do not immediately arise from an exter-
* The subject of muscular contraction and other questions relating to the functional
activity of muscle, treated of in former editions of this work, have outgrown the
space that could be allotted to their consideration here; and as, moreover, they properly
belong to a treatise on physiology, they have now been omitted.
cxxxii NERVOUS SYSTEM.
iial stimulus, and do not manifest themselves in outward acts. To this class
also belong sensation and volition. In the exercise of sensation the mind be-
comes conscious, through the medium of the brain, of impressions conducted
or propagated to that organ along the nerves from distant parts ; and in
voluntary motion a stimulus to action arises in the brain, and is carried
outwards by the nerves from the central organ to the voluntary muscles.
Lastly, emotion, which gives rise to gestures and movements varying with
the different mental affections which they express, is an involuntary state of
the mind, connected with some part of the brain, and influencing the
muscles through the medium of the nerves.
The remaining functions of the nervous system do not imply necessary
participation of the mind. In the production of those movements, termed
reflex, excited, or excito-motory, a stimulus is carried along afferent nerve-
fibres to the brain or spinal cord, and is then transferred to efferent or
motor nerve-fibres, through which the muscles are excited to action ; and
this takes place quite independently of the will, and may occur without
consciousness. The motions of the heart, and of other internal organs, the
contraction of the coats of the blood-vessels, as well as the invisible changes
which occur in secretion and nutrition, are in a certain degree subject to the
influence of the nervous system, and are undoubtedly capable of being modi-
fied through its agency ; though, with regard to some of these phenomena, it is
doubtful how far the direct intervention of the nervous system is necessary
for their production. These actions, which are all strictly involuntary, are,
no doubt, readily influenced by mental emotions ; but they may also be
affected through the nerves in circumstances which entirely preclude the
participation of the mind.
The nervous system consists of a central part, or rather a series of con-
nected central organs, named the cerebro-spinal axis, or cerebro- spinal centre ;
and of the nerves, which have the form of cords connected by one extremity
with the cerebro-spinal centre, and extending from thence through the body
to the muscles, sensible parts, and other organs placed under their control.
The nerves form the medium of communication between these distant parts
and the centre. One class of nervous fibres, termed afferent or centripetal,
conduct impressions towards the centre, another, the efferent or centrifugal,
carry motorial stimuli from the centre to the moving organs. The nerves
are, therefore, said to be internuncial in their office, whilst the central organ
receives the impressions conducted to it by the one class of nerves, and im-
parts stimuli to the other, rendering certain of these impressions cognisable
to the mind, and combining in due association, and towards a definite end,
movements, whether voluntary or involuntary, of different and often of dis-
tant parts.
Besides the cerebro-spinal centre and the nervous cords, the nervous
system comprehends also certain bodies named ganglia, which are connected
with the nerves in various situations. These bodies, though of much smaller
size and less complex nature than the brain, agree, nevertheless, with that
organ in their elementary structure, and to a certain extent also in their
relation to the nervous fibres with which they are connected ; and this cor-
respondence becomes even more apparent in the nervous system of the lower
members of the animal series. For these reasons, as well as from evidence
derived from experiment, but which is of a less cogent character, the ganglia
are regarded by many as nervous centres, to which impressions may be
referred, and from which motorial stimuli may be reflected or emitted ; but
of local and limited influence as compared with the cerebro-spinal centre, and
CHEMICAL COMPOSITION. cxxxiii
operating without our consciousness and without the intervention of the
will.*
The nerves are divided into the cerebro-spinal, and the sympathetic or
ganglionic nerves. The former are distributed principally to the skin, the
organs of the senses, and other parts endowed with manifest sensibility, and
to muscles placed more or less under the control of the will. They are
attached in pairs to the cerebro-spinal axis, and like the parts which they
supply are, with few exceptions, remarkably symmetrical on the two sides of
the body. The sympathetic or ganglionic nerves, on the other hand, are
destined chiefly for the viscera and blood-vessels, of which the motions are
involuntary, and the natural sensibility is obtuse. They differ also from the
cerebro-spinal nerves in having generally a greyish or reddish colour, in
their less symmetrical arrangement, and especially in the circumstance that
the ganglia connected with them are much more numerous and more gene-
rally distributed. Branches of communication pass from the spinal and
several of the cerebral nerves at a short distance from their roots, to join the
sympathetic, and in these communications the two systems of nerves mutually
give and receive nervous fibres ; so that parts supplied by the sympathetic
may be also in nervous connection with the cerebro-spinal centre.
The nervous system is made up of a substance proper and peculiar to it,
with inclosing membranes, nutrient blood-vessels, and supporting connective
tissue. The nervous substance has been long distinguished into two kinds,
obviously differing from each other in colour, and therefore named the white,
and the grey or cineritious.
CHEMICAL COMPOSITION.
The information we possess respecting the chemical composition of nervous
matter is for the most part founded on analyses of portions of the brain and
spinal cord ; but the substance contained in the nerves, which is continuous
with that of the brain and cord, and similar in physical characters, appears
also, as far as it has been examined, to be of the same general chemical con-
stitution. No very careful comparative analysis has yet been made of the
grey and white matter, to say nothing of the different structural elements of
the nervous substance ; and indeed it must be remembered, that, in portions
of brain subjected to chemical examination, capillary blood-vessels, connec-
tive and perhaps other accessory tissues, as well as interstitial fluid, are
mixed up in greater or less quantity with the true nervous matter, and must
so far affect the result.
The nervous matter may be said to consist of an albuminoid body, in part
liquid, with fatty principles, extractive matters, salts, and much water. The
water, which forms from three-fourths to four-fifths or more of the whole
cerebral substance, may be removed by immersion in alcohol and evapora-
tion. When the solid matter which remains after removal of the water is
treated with ether and hot alcohol, the fatty compounds are extracted from
it by these menstrua, and there remains a mixture of coagulated albuminous
matter and salts, with a small remnant due to accessory tissues, chiefly vessels.
The albuminoid constituent is not sufficiently known to be characterised specifically.
It no doubt belongs, in some small proportion, to the interstitial fluid. Of that which
* From the researches of Dr. Augustus Waller it appears probable that ganglions
exert some influence over the nutrition of the nerve-fibres connected with them, and
serve to maintain the structural integrity of these fibres ; for it has been found that, when
a ganglionic nerve is cut across in a living animal, the part beyond the section after a
time becomes atrophied, while the part connected with the ganglion retains its integrity.
Tc
cxxxiv NEKVOUS SYSTEM.
is contained in the proper nervous substance, a portion forming the central part of
the nerve-fibres (axis-cylinder) appears in microscopic observations to be solid ;
whilst in the surrounding part (medullary sheath) the albuminoid is liquid and in-
corporated with fatty matter, also liquid, being probably combined as a colloid with
the fat, in the way pointed out by Mr. Graham (see ante, page vii). The fats are
1. The cerebric acid of Fremy, called cerebrin by Gobley, because he considers it a
neutral body, acid only from contamination with phosphoric acid, but containing
phosphorus, which also is regarded as an impurity by W. Miiller.
2. Oleo-phosphoric acid of Fremy, a very unstable compound, held by Gobley to
be a mixture of oleic acid and his gl ycero-phosphoric acid, which, it may be remarked,
he has found also in the yelk of the egg.
3. Olein, margarin, and palmitin, with their acids.
4. Cholesterin although this is no longer considered a true fat, and may, moreover,
"be a product of tissue-change.
The extractive matters probably belong chiefly to the interstitial fluid ; but, how-
ever this may be, they may be held to represent the products of decomposition of
the nervous substance. The following have been recognised :
1. Lactic, formic, acetic, and (traces of) uric acid.
2. Inosit.
3. Kreatin.
4. Hypoxanthin (or sarkin).
5. Leucin(in the ox).
In regard to free acid, Funke has found the same law to prevail in nerve as in
muscle namely, that the substance of nerves in the living but quiescent state is
neutral, but becomes acid after death or prolonged excitement. The saline or inor-
ganic matters found by incineration are phosphoric acid, phosphates of alkalies,
which, as in muscle, largely predominate over other salts, potash, as a base, largely
exceeding soda ; earthy phosphates, in smaller proportion, magnesia prevailing over
lime ; phosphate of iron ; chloride of sodium, sulphate of potash, and a trace of
silica. From fresh brain-substance Breed obtained - 027 per cent, of ashes, which
per 100 parts yielded 55'24 phosphate of potash, 22 93 phosphate of soda, V23 phos-
phate of iron, r<32 phosphate of lime, 3*4 phosphate of magnesia, 474 chloride of
sodium, T64 sulphate of potash (the sulphuric acid doubtless from combustion of
principles containing sulphur), 9'15 free phosphoric acid (from combustion of phos-
phorus), and 0*42 silicic acid.
The white substance contains nearly 75 per cent, of water; the grey about 85;
the proportion of water is less in the spinal cord, and still less in the nerves. The
fat amounts in the grey matter to nearly 5 and in the white to nearly 15 per cent.;
in the nerves the proportion fluctuates largely. It is worthy of note that the brain,
during embryo and infantile life, contains much less fat and more water ; moreover,
the grey and the white matter do not present the same differences as in after life in
the proportions of water and fat which they respectively contain. The brain of
embryos of from ten to twenty-two weeks has been found to yield only from 0'99 to
1-5 per cent of fat ; that of the full grown foetus from 3 to 4 per cent. The water in
the foetal brain at birth is about 85 per cent., both in the white and the grey sub-
stance.
STRUCTURAL ELEMENTS.
When subjected to the microscope, the nervous substance is seen to con-
sist of two different structural elementa, viz., fibres and cells. The fibres
are found universally in the nervous cor<ls, and they also constitute the
greater part of the nervous centres : the cells on the other hand are con-
fined in a great measure to the cerebro-spinal centre and the ganglia, and do
not exist generally in the nerves properly so called, although they have been
found at the terminations of some of the nerves of special sense, and also
interposed here and there among the fibres of particular nerves ; they are
contained in the grey portion of the brain, spinal cord, and ganglia, which
grey substance is in fact made up of these cells intermixed in many parts
with fibres, and with a variable quantity of supporting connective substance.
NERVE-FIBRES.
In further pursuing the subject, we shall first examine the fibres and cells
by themselves, and afterwards consider the structure of the parts which they
contribute to form, viz. , the cerebro-spinal organs, the ganglia, and the nerves.
The fibres are of two kinds : 1, the ivhite, tubular, medullated, or dark
bordered, and 2, the grey, pale, non-medullated, or gelatinous. The former
are by far the most abundant ; the latter are found principally in the
sympathetic nerve, but are known to exist also in many of the cerebro-
spinal nerves.
The White or Tubular Fibres (fig. LXXIV). These form the white part of
the brain, spinal cord, and nerves. When collected in considerable num-
bers and seen with reflected light, the mass which they form is white and
Fig. LXXIV.
, IV<
Fig. LXXIV. A. WHITE OB TUBULAR NERVE-FIBRES, showing the sinuous outline and
double contours.
B. DIAGRAM to show the parts of a tubular fibre, viz. 1, 1, membranous tube. 2, 2,
white substance or medullary sheath. 3, axis or primitive band.
o. DIAGRAM intended to represent the appearances occasionally seen in the tubular
fibres. 1, 1, membrane of the tube seen at parts where the white substance has separated
from it. 2, a part where the white substance is interrupted. 3, axis projecting beyond
the broken end of the tube. 4, part of the contents of the tube escaped.
opaque. Viewed singly, or few together, under the microscope, with trans-
mitted light, they are transparent ; and if quite fresh from a newly killed
animal, and unchanged by cold or exposure, they appear as if entirely homo-
geneous in substance, like threads of glass, and are bounded on each side by
a simple and usually gently sinuous outline. Their size differs considerably
even in the same nerve, but much more in different parts of the nervous
system ; some being as small as the -pgiro^k anc * otners upwards of the
j-^o-y-th of an inch in diameter ; moreover, the same fibre may change its
size in different parts of its course, and it is generally smaller at its central
and peripheral ends. Very speedily after death, and especially on exposure
to the action of water, these seemingly homogeneous fibres become altered :
k 2
cxxxvi NERVOUS SYSTEM.
and it is when so altered that they are commonly subjected to examination,
as represented in fig. LXXIV A. In particular instances, and in favourable cir-
cumstances, it may be discovered that the fibre is composed of a fine mem-
branous tube, inclosing a peculiar soft substance, and that this contained
substance itself is distinguishable into a central part placed like a sort of
axis in the middle of the tube, and a peripheral portion surrounding the
axis, and occupying the space between it and the tubular inclosing mem-
brane. In the annexed ideal plan (fig. LXXIV B), the membranous tube, or
primitive sheath, is marked 1, 1 : the central part, marked 3, was named
cylinder-axis by Purkinje, who considered it to be identical with the struc-
ture previously described by Remak under the name of the primitive band
(fibra primitiva) ; the matter surrounding it, marked 2, 2, is supposed to be
the chief cause of the whiteness of the brain and nerves, and it was accord-
ingly named the white substance by Schwann, and by others, though less
appropriately, the medullary sheath. It is this last-mentioned substance
which undergoes the most marked change on exposure ; it then seems to
suffer a sort of coagulation or congelation, and when this has taken place,
it very strongly refracts the light, and gives rise to the appearance of a dark
border on each side of the nerve tube (fig. LXXIV, A and c). This border,
though darker than the rest of the tube, is nevertheless translucent, and is
either colourless, or appears of a slightly yellowish or brownish tint ; it is
bounded by two nearly parallel lines, so that the nerve-fibre has then a
double contour, and the inner line, less regular than the outer, gradually
advances further inwards as the change in the white substance extends to a
greater depth. The dark contours pursue a sinuous course, often with deep
and irregular indentations ; while straight or curved lines of the same cha-
racter, occasioned no doubt by wrinkles or creases occurring in the layer of
white substance, are frequently seen crossing the tube. By continued ex-
posure, round and irregular spots appear at various points, and at length
the contents of the nerve-tube acquire a confusedly curdled or granulated
aspect.
The double contour appears only in fibres of a certain size; in very fine tubes,
which become varicose or dilated at intervals, the double line is seen only in the
enlargements, and not in the narrow parts between. It often happens that the soft
contents of the tube are pressed out at the ruptured extremities, as in fig. LXXIV.
c, 4, and then the round or irregular masses of the effused matter p.re still surrounded
by the double line, which proves that this appearance is produced independently of
the membranous tube. So long as this tube is accurately filled by the contained
matter, its outline cannot be distinguished : but sometimes, when the white sub-
stance separates at various points from the inside of the tube, the contour of the fibre
becomes indented and irregular, and then the membrane of the tube may, in favour-
able circumstances, be discerned as an extremely faint line, running outside the
deeply shaded border formed by the white substance, and taking no part in its irre-
gular sinuosities (fig. LXXIV, c, 1. 1). The membranous tube may also be distinguished
at parts where the continuity of the contained matter is broken in consequence of
traction, squeezing, or like injury of the fibre; in such parts the double line produced
by the white substance is wanting, and the faint outline of the membranous tube may
be perceived passing over the interruption (2). The fine transparent membrane
which forms this tube, named also the primitive sheath, appears to be quite simple
and homogeneous in structure ; so far as can be judged, it agrees in chemical nature
with elastic tissue. Treatment with weak chromic acid, or iodine, or, still better,
staining with carmine or aniline-red (magenta), brings into view nuclei attached
along the sheath. They are found on the fibres of the nerves generally, but not in
the optic and auditory nerves, nor in the brain and spinal cord ; and, indeed, it is
still a question whether the fibres of these last-named nerves and nervous centres are
provided with a membranous sheath.
NERVE-FIBKES.
CXXXVll
The axis cylinder, axis-bandy or axial fibre is situated in, or near, the
miklle of the nerve-tube, where it may occasionally be seen, on a careful
inspection, as a greyish stripe or baud, bounded on each side by a very
faint even outline, having no share in the sinuosities of the white substance
(fig. LXXIV, c).
The axis is of a more tenacious consistence than the white substance, and may accord-
ingly be sometimes seen projecting beyond it at the end of a broken nerve-tube, either
quite denuded, or covered only by the tubular membrane, the intervening white sub-
stance having escaped. Although the name of axis-cylinder would seem to imply that
it has actually a cylindrical figure, yet this is by no means certain; and whether
naturally cylindrical or not, it certainly very generally appears more or less flattened
when subjected to examination. To all outward appearance, usually, it is solid and
homogeneous, but sometimes it is striated longitudinally, and towards its termination
at the peripheral extremity of the nerve, it very commonly divides into finer filaments.
The axis-cylinder consists of a solid albuminoid substance, whereas the medullary
sheath or white substance consists mainly of fat and a certain proportion of albu-
minous matter, combined with it as a colloid into an oleo-albuminous liquid. Accord-
ingly, whilst water, especially when cold, rapidly produces congelation of the white
substance, ether, on the other hand, causes it speedily to disappear as if by solution,
and globules of oil then make their appearance both within and without the tube, the
remaining contents becoming granular from precipitation of albumen.
The existence of an axial fibre is probably universal in nerve-fibres, though it is not
generally visible without preparation. To bring it into view, a solution of carmine or
aniline-red (magenta) may be used, which stains it red first colouring the denuded
and projecting ends, but finally also the parts still surrounded with the medullary
sheath. Glacial acetic acid, chromic acid, iodine, alcohol, chloroform, collodium, and
other reagents, are also employed with greater or less advantage.
Many of the tubular nerve-fibres, when Fig- LXX V.
subjected to the microscope, appear di-
lated or swollen out at short distances
along their length, and contracted in the
intervals between the dilated parts. Such
fibres have been named varicose (fig.
LXXV). They occur principally in the
brain and spinal cord, and in the intra-
cranial part of the olfactory, in the optic,
and acoustic nerves ; they are occasion-
ally met with also in the other nerves,
especially in young animals. These fibres,
however, are naturally cylindrical like
the rest, and continue so while they re-
main undisturbed in their place ; and the
varicose character is occasioned by pres-
sure or traction during the manipulation,
which causes the soft matter contained
in the nerve-tube to accumulate at cer-
tain points, whilst it is drawn out and
attenuated at others. Most probably
the change takes place before the white
substance has coagulated. The fibres in
which it is most apt to occur are usually
of small size, ranging from ^ ^th to
j-g^- -tli of an inch in diameter ; and
when a very small fibre is thus affected,
the varicosities appear like a string of (from' Valentin).
Fig.
LXXV. FIBRES FROM THE ROOT
OF A SPINAL NEKVE.
At a, where they join the spinal
cord, they are varicose ; lower down
at b, they are uniform and larger
cxxxviii
NERVOUS SYSTEM.
globules held together by a fine transparent thread. As already remarked,
the double contour caused by congelation of the white substance does not
appear in the highly constricted parts. The axis takes no part in this
change, indeed it may sometimes be seen running through the varicosities
and undergoing no corresponding dilatation.
Neither in their course along the nervous cords, nor in the white part of
the nervous centres, have these tubular fibres ever been observed to unite or
anastomose together, nor are they seen to divide into branches ; it is there-
fore fair to conclude that, though bound up in numbers in the same nervous
cords, they merely run side by side like the threads in a skein of silk, and
that they maintain their individual distinctness throughout the trunk and
branches of a nerve ; but in many cases the fibres divide in approaching the
peripheral termination of the nerve, as will be again noticed.
Grey, Pale, Non-medullated, or Gelatinous Fibres (fig. LXXVI). The white
fibres, at the peripheral extremities of many nerves, lay aside their medul-
lary sheath and dark borders, and are prolonged into pale fibres, often
Fig. LXXVI.
A
Fig. LXXVI. GREY, PALE OR GELATINOUS NERVE-FIBRES (from Max Schultze.
Magnified between 400 and 500 diameters).
A. From a branch of the olfactory nerve of the sheep; at a, a, two dark bordered
or white fibres, from the fifth pair, associated with the pale olfactory fibres.
B. From the sympathetic nerve.
minutely dividing, which seem to represent the axis-cyliuder deprived of
surrounding white substance, and either naked or covered with a prolonga-
tion of the primitive sheath. But, apart from these pale continuations of
white fibres, there are nerve-fibres which exhibit the non-medullated charac-
ter throughout their whole length. These are the pale grey fibres first
pointed out by Remak, and commonly designated by his name, which are
found, with or without associated white fibres, chiefly in the sympathetic but
also in other nerves. The branches of the olfactory nerve of man and
mammalia consist wholly of these pale fibres. They were named gelatinous
(by Henle) from their aspect, not their chemical nature. They measure
from -g-J^th to ^^ ^th of an inch in diameter, appear flattened, translucent,
homogeneous, or very faintly granular, and sometimes finely striated longi-
tudinally. At short distances they bear oblong nuclei, which have been
supposed to belong to a sheath (Max. Schultze). As these fibres generally end
peripherally and some (olfactory) are known to begin centrally by a
NERVE-CELLS.
CXXX1X
Fig. LXXVII.
number of fiue fibrils, it has been by some anatomists suggested, by others
maintained, that they are really bundles of immeasurably fine filaments ;
moreover, it is asserted that the fibrillar structure may be actually observed
in pale sympathetic fibres ; but this view, however probable, stands in need
of confirmation.
Pale fibres are also met with (in the sympathetic nerve especially) which
appear as fine simple filaments with fusiform enlargements, often finely
granular in substance, and possibly of the nature of nuclei, but placed in
the continuity of the fibre, and not merely attached to a sheath.
Nerve-cells, sometimes called Nerve-vesicles.
These, as already mentioned, constitute
the second kind of structural elements proper
to the nervous system. They are found in
the grey matter of the cerebro-spinal centre
and ganglions, constituting a principal part
of the last-mentioned bodies, and thence
often named gaitylionic corpuscles or ganglion-
globules ; they exist also in some of the nerves
of special sense at their peripheral expan-
sions, and, here and there, in the course of cer-
tain other nerves. The nerve-cells may have
a spheroidal, oval, or pyriform shape (fig.
LXXVII); and such for the most part is their
form in the ganglions ; but many, and espe-
cially those from the grey matter of the
spinal cord and brain, are of an angular or
irregular figure, and send out processes,
Fig. LXXVII. GANGLIONIO
NERVE-CELLS, MAGNIFIED (from
Valentin).
Fig. LXXVIII.
Fig. LXXVIII. RAMIFIED NERVE-CELL, FROM THE GREY MATTER OF THE HUMAN
MEDULLA OBLONGATA. MAGNIFIED 350 DIAMETERS (from Kolliker).
cxl NERVOUS SYSTEM.
often finely branched, from their circumference (figs. LXXVIII and LXXIX);
and then they are often named, according to the number of processes they
present, uni-, bi-, and multipolar ; terms obviously ill chosen, but rendered
Fig. LXXIX.
Fig. LXXIX. NERVE-CELLS FROM THE CORTICAL GREY MATTER OP THE CEREBELLUM.
MAGNIFIED 260 DIAMETERS (from Kolliker, reduced).
current by use. They have each, as a rule, a large, well-defined, clear,
round nucleus, and within this an equally distinct nucleoltis, or sometimes
more than one. The substance of the cell is soft and translucent, but finely
granular or punctuated, and slightly tinged throughout with a brownish red
colour ; and cells are often seen, especially those of the large ramified kind,
with one, or sometimes two, much deeper coloured brown patches, caused
by groups of pigment granules ; the colour is deeper in adult age than in
infancy.
The bodies in question, although they still are commonly called " cells/'
appear to be destitute of a proper cell-wall. In the ganglia, it is true, they
are enclosed in a distinct capsule ; but this is probably adventitious, and
pertaining to the connective structure in which they are lodged. The out-
runners or branches are formed by prolongations of the same soft substance
which forms the cell-body ; they are, therefore, very readily broken, and
the cells thereby mutilated, in the manipulation required for their insulation.
Various recent observers describe a faint striation, or a very fine fibrillation, in the
branched cells; the lines or fibrils are said to run along the outrunners, and also to
pass continuously through the body of the cell from one branch to another ; it is
further alleged by one writer (Frommann), that bundles of filaments proceed from the
nucleus and pass out of the cell at various points, in each of which bundles there is one
fibril connected with the nucleolus.
Other nerve-cells (fig. LXXX, a) are found in the nervous substance, which
are distinguished chiefly by the pellucid, colourless, and homogeneous aspect
of the matter contained in them ; such cells possess a nucleus like the rest ;
they are seldom large, and have usually a simple round or oval figure. They
occur along with nerve-cells of the kind before described. Lastly, small
bodies of the size of human blood-corpuscles and upwards, containing one
or more bright specks like nucleoli, abound in the grey matter in certain
situations (fig. LXXX, 6, c). These bodies, which are sometimes called
"granules" (Korner in German), resemble the nuclei of nerve-cells; and
it may be a question whether they are not the nuclei of cells in which the
GAXGLIA.
cxli
Fig. LXXX.
cell-matter or protoplasm is very scanty, and accidentally detached in exami-
nation. These nucleus-like bodies are very abun-
dant in the superficial grey matter of the cere-
bellum.
In the grey matter of the cerebro-spinal centre,
the nerve-cells appear as if imbedded in a sort
of matrix of granular substance, interposed be-
tween them in greater or less quantity, and
very generally traversed by nerve-fibres. But
it is very probable that the appearance of gra-
nular or molecular matter results from a con-
fused interlacement of very fine fibrils, and
especially of the fine ramifications of nerve-
cells ; or from the crushing and breaking down
of such fibres in the process of examination.
In the ganglia properly so called, the cells are
packed up among nerve- fibres, but each cell is
also immediately surrounded by an inclosing
capsule (fig. LXXXII. and LXXXIII.).
The proper nervous substance of the brain
and spinal cord is described by Kolliker as being
traversed in all directions and supported by a
framework of connective tissue the " reti-
form " connective tissue described at page Ixxix. This is formed of an inter-
union of ramified connective tissue corpuscles, or
of a network of fine fibres alone, originally pro-
ceeding from such corpuscles. Kolliker names this
supporting structure the reticulum of the nervous
centres (fig. LXXXL). Virchow proposes the term
neuroglia. It is not merely an open mesh-work,
but consists also of fine laminae formed of a close
interlacement of the finest fibrils, disposed as mem-
branous partitions and tubular compartments for
separating and inclosing the nervous bundles.
Such being the structural elements of the ner-
vous substance, we have next to consider the ar-
rangement of these cells and fibres in the ganglia
and nerves which they contribute to form ; the
intimate structure of the eucephalon and spinal cord
being treated of in the part of this work which is
devoted to special or descriptive anatomy.
Fig. LXXX. SMALL NERVE-
CELLS.
a, from the (cortical) grey
matter of the brain. 6 and c
are from the cortical substance
of the cerebellum ; b resemble
detached cell-nuclei. c are
smaller bodies, also like cell-
nuclei, densely aggregated
(from Hannover, magnified
340 diameters).
Fig. LXXXL
Fig. LXXXL PART OP
TUB RETICULUM FROM
THE SPINAL CORD.
Open meshes are seen ge-
nerally, but at two places
the close lamelliform in-
terlacements are shown.
Magnified 350 diameters
(from Kolliker).
OF THE GANGLIA.
The bodies so named are found in the following situations viz. : 1. On
the posterior root of each of the spinal nerves, on one, and probably the
corresponding root of the fifth nerve of the encephalon, and on the seventh
pair, glosso-pharyngeal and pneumogastric nerves, involving a greater or less
amount of their fibres ; also on the branches of certain cerebro-spinal
nerves. 2. Belonging to the sympathetic nerve, (a) In a series along
each side of the vertebral column, connected by nervous cords, and con-
stituting what was once considered as the trunk of the sympathetic.
(6) On branches of the sympathetic ; occurring numerously in the abdomen,
thorax, neck, and head ; generally in the midst of plexuses, or at the point
cxlii NERVOUS SYSTEM.
of union of two or more branches. Those which are found in several of the
fosss9 of the cranium and face are for the most part placed at the junction of
fine branches of the sympathetic with branches, usually larger, of the cerebro-
spinal nerves ; but they are generally reckoned as belonging to the sympa-
thetic syotem.
The ganglia differ widely from each other in figure and size : those which
have been longest known to anatomists are most of them large and con-
spicuous objects ; but, by the researches of Kemak and others, it has been
shown that there are numerous small, or what might be almost termed
microscopic ganglia, disposed along the branches of nerves distributed to the
tongue, the heart, the lungs, and some other viscera ; also connected with
fine plexuses of nerves between the coats of the intestines.
Ganglions are invested externally with a thin but firm and closely adherent
envelope, continuous with the fibrous sheath of the nerves, and composed of
connective tissue ; this outward covering sends processes inwards through
the interior mass, dividing it, as it were, into lobules, and supporting the
numerous fine vessels which pervade it. A section carried through a ganglion,
in the direction of the nervous cords connected with it, discloses to the uak<>d
eye merely a collection of reddish-grey matter traversed by the white fibres
of the nerves. The nervous cords on entering lay aside their investing
sheath and spread out into smaller bundles, between which the grey gang-
lionic substance is interposed ; and their fibres are gathered up again into
cords, furnished with sheaths, on issuing from the ganglion. The micro-
scope shows that this grey substance consists of nerve-cells and fibres with
supporting connective tibsue. The nerve-cells, or ganglion-globules, have
mostly a round, oval, or pyriform figure (figs. LXXVIL, LXXXII; and LXXXIII.).
They are inclosed in capsules formed of a transparent membrane with
attached or imbedded nuclei.
Of the relation between the nerve-fibres in a ganglion and the ganglion-cells,
it may be stated that many fibres pass through without being connected with
the cells, but that every nerve-cell is connected with a fibre or with fibres.
According to Dr. Beale, each cell is connected with, at least, two fibres,
which, on reaching the nervous bundle in which they are distributed, run in
opposite directions (fig. LXXXII). One of the fibres is straight, usually of
tolerable size, and connected with the cell at one spot like a stalk in pyri-
form cells at the small end. The other, usually smaller, begins or is
attached at some distance from the insertion of the first, and makes several
turns on the surface of the cell, but within its capsule, which are continued
as spiral coils round the straight fibre, and then the two part company and,
apparently, run in opposite directions in the nervous bundle in which they
mingle.
The spiral fibre bears large oblong nuclei along its course. These are seen on its
spiral turns upon the surface of the cell, and some, at the commencement of the
fibre, seem to be beneath the surface. It may be single from the first, or begin by
two or more filaments which join at some distance from the cell. Both fibres in-
crease in size as they proceed. They have at first the character of pale fibres (or axis-
cylinders), then one ot them generally the straight one, but it may be the other
at a short distance from the cell acquires a medullary sheath and becomes a dark
bordered fibre. At the same time it cannot be positively said that both fibres may
not become dark bordered, or both continue as pale fibres. The spiral fibres may
make more or fewer coils, and Dr. Beale thinks they are more numerous in
older cells for in some cases the smaller fibre (answering to the spiral one
elsewhere) is not coiled ; and the cells in such cases he considers to be young or
recently formed.
GANGLIA.
cxliii
Dr. Beale's observations have been made chiefly on the ganglia of frogs, the cells of
which have very commonly a pyriform shape like the one represented in the figure.
In mammalia they are more spheroidal, and the observation of their connection with
fibres is more difficult; but from examinations in mammalia, so far as they have gone,
Dr. Beale infers that the relation of the cells and fibres is essentially the same as in
frogs.
Fig. LXXXII.
Fig. LXXXI1I.
Fig. LXXXII. GANGLION-CELL OP A FROG, MAGNIFIED; ACCORDING TO BEALE.
Reduced and adapted from one of his figures, a, a, straight fibre ; b, b, coiled fibre ;
C, smaller one joining it.
Fig. LXXXIII. MAGNIFIED GANGLION-CELL, PROM THE SYMPATHETIC OF THE FROG,
ACCORDING TO J. ARNOLD. Virch. Arch. 1865.
a, straight fibre ; b, coiled fibre, arising by a superficial net connected with nucleolus
of the cell ; c, c, capsule with nuclei.
Two subsequent writers, Julius Arnold, and L. G. Courvoisier, have confirmed
Dr. Beale's original observation in almost every point ; but whilst Beale describes
the two fibres as connected with the substance of the cell and at its surface only or,
at least, could not obtain satisfactory evidence of its passing into the interior
Arnold, and (after him) Courvoisier describe (has had previously been done by Har-
less and others) the straight fibre as traceable into the nucleus, with which Arnold
thinks its medullary sheath, here altogether inconsiderable, is continuous, whilst the
axial part ends in the nucleolus, which he regards as the knobbed end of the axis-
cylinder. They both describe a network of exquisitely fine fibrils, which, springing
from the nucleolus as a centre, traverses the substance of the celt and comes to the
surface between the celt-body and its sheath, and finally unites into the spiral fibre.
According to this account, the nucleolus is, as it were, the end of the straight fibre and
beginning of the spiral one, or vice versa ; or, at least, the point of organic connection
between them in the cell.
cxliv NERVOUS SYSTEM.
Courvoisier describes both fibres as acquiring a medullary sheath, the straight one
first. He has found the above described structure in the ganglia of fish, birds, and
mammals ; but whilst in the frog the cell has never, or scarcely ever, more than one
straight and very rarely more than one spiral fibre, he finds that in other vertebrates
a cell may give off such twin fibres from two or more parts of its circumference.
In the spinal ganglia of the skate, torpedo, and dog-fish, there is a different arrange-
ment. In these, as first pointed out by R. Wagner, two fibres are connected with
each ganglion-cell, at opposite sides or opposite poles, one directed centrally toward
the root of the nerve, and the other outwardly towards its branches.
CEREBKO- SPINAL NERVES.
These are formed of the nerve-fibres already described, collected together
and bound up in sheaths of connective tissue. A larger or smaller number
of fibres inclosed in a tubular sheath form a slender round cord of 110 deter-
minate size, usually named a funiculus ; if a nerve be very small it may
consist of but one such cord,
rig. .. . . . , .,
but in larger nerves several fum-
culi are united together into
one or more bundles, which,
being wrapped up in a com-
mon membranous covering, con-
stitute the nerve (fig. LXXXIV.).
Fig. LXXXIV. -PORTION OF THE TRUNK OF A NERVE Accordillg i y in dissecting a
CONSISTING OF MANY SMALLER CORDS OR FUNICULI
WRAPPED UP IN A COMMON SHEATH. nerV6 > W6 nrsfc COme t0 ftl1 OUt '
., i r T j <. ward covering, formed of con-
A, the nerve ; B, a single funiculus drawn out
from the rest (from Sir C. Bell). nective tissue, often so strong
and dense that it might well be
called fibrous. From this common sheath we trace laminae passing inwards
between the larger and smaller bundles of funiculi, and finally between the
funiculi themselves, connecting them together as well as conducting and sup-
porting the fine blood-vessels which are distributed to the nerve. But, besides
the interposed areolar tissue which connects these smallest cords, each funi-
culus has a special sheath of its own, as will be further noticed presently.
The common sheath and its subdivisions consist of connective tissue, pre-
senting the usual white and yellow constituent fibres of that texture, the
latter being present in considerable proportion. The special sheaths of the
funiculi, on the other hand, appear to be formed essentially of a fine trans-
parent membrane, which may without difficulty be stripped off in form of a
tube from the little bundle of nerve-fibres of which the funiculus consists.
When examined with a high power of the microscope, this membrane
presents the aspect of a thin transparent film, which in some parts appears to
be quite simple and homogeneous, but is more generally marked with
extremely fine reticulated fibres. Corpuscles resembling elongated cell-
nuclei may also be seen upon it when acetic acid is applied. The tissue in-
vesting a nerve and inclosing its proper fibres, as now described, is named
the neurilemma, and the term is for the most part applied indiscriminately
to the whole of the enveloping structure, though some anatomists use it to
denote only the sheaths of the funiculi and smaller fasciculi, whilst they
name the general external covering of the nerve its *' cellular sheath. " (vagina
cellulosa).
Some recent writers, believing that the primitive sheath or membranous
tube of the nerve-fibre corresponds to the sarcolemma of muscle, have pro-
posed to designate it as the neurilemma, and to use the term perineurium
for the coarser sheathing of the nerves and nervous cords, to which the term
CEKEBRO-SPIXAL NEEVES. cxlv
nenrilemma has been heretofore applied. The use of the term perineurium
is unobjectionable and may sometimes be convenient, but the proposed new
and restricted application of the term neurilemma will, I think, lead to am-
biguity, and is of doubtful propriety.
The funiculi of a nerve are not all of one size, but all are sufficiently
large to be readily seen with the naked eye, and easily dissected out from
each other. lu a nerve so dissected into its component funiculi, it is seen
that these do not run along the nerve as parallel insulated cords, but join
together obliquely at short distances as they proceed in their course, the
cords resulting from such union dividing in their further progress to form
junctions again with collateral cords ; so that in fact the funiculi composing
a single nervous trunk have an arrangement with respect to each other
similar to that which we shall presently find to hold in a plexus formed by
the branches of different nerves. It must be distinctly understood, how-
ever, that iu these communications the proper nerve-fibres do not join to-
gether or coalesce. They pass off from one nervous cord to enter another,
with whose fibres they become intermixed, and part of them thus inter-
mixed may again pass off to a third funiculus, or go through a series of
funiculi and undergo still further intermixture ; but throughout all these
successive associations (until near the termination of the nerve) the fibres
remain, as far as known, individually distinct, like the threads in a rope.
The fibres of the cerebro-spinal nerves are chiefly, in some cases perhaps
exclusively, of the white or medullated kind, but in most instances there
are also grey fibres in greater or less number. Moreover, it has often
appeared to me as if there were filaments of extreme tenuity, like the white
filaments of connective tissue, but of doubtful nature, mixed up with well-
characterised nerve-fibres within the sheaths of the funiculi. Lying along-
side each other, the fibres of a fuuiculns form a little skein or bundle, which
runs in a waving or serpentine manner within its sheath ; and the alternate
lights and shadows caused by the successive bendings being seen through
the sheath, give rise to the appearance of alternate light and dark cross
stripes on the funiculi, or even on larger cords consisting of several fuuiculi.
On stretching the nerve, the fibres are straightened and the striped appear-
ance is lust.
Vessels. The blood-vessels of a nerve supported by the sheath divide
into very fine capillaries, said by Heule to measure in the empty state not
more than ^'^th. f an i ncn i" diameter. These, which are numerous, run
parallel with the fibre.-*, many of them within the funicular sheaths, but are
connected at intervals by short transverse branches, so as in fact to form
a network with long narrow meshes.
Branching and conjunction of Nerves. Nerves in their progress very
commonly divide into branches, and the branches of different nerves not
unfrequently join with each other. As regards the arrangement of the
fibres in these cases, it is to be observed, that, in the branching of a nerve,
collections of its fibres successively leave the trunk and form branches ; and
that, when different nerves or their branches intercommunicate, fibres pass
from one nerve to become associated with those of the other in their further
progress ; but in neither case (unless towards their peripheral terminations)
is there any such thing as a division or splitting of an elementary nerve-
fibre into two, or an actual junction or coalescence of two such fibres
together.
A communication between two nerves is sometimes effected by one or
two connecting branches. In such comparatively simple modes of connec-
cxlvi NERVOUS SYSTEM.
tion, which are not unusual, both nerves commonly give and receive fibres ;
so that, after the junction, each contains a mixture of fibres derived from
two originally distinct sources. More rarely the fibres pass only from one
of the nerves to the other, and the contribution is not reciprocal. In the
former case the communicating branch or branches will of course contain
fibres of both nerves, in the latter of one only.
In other cases the branches of a nerve, or branches derived from two or
from several different nerves, are connected in a more complicated manner,
and form what is termed a plexus. In plexuses of which the one named
" brachial " or " axillary," formed by the great nerves of the arm, and the
" lumbar" and "sacral," formed by those of the lower limb and pelvis, are
appropriate examples the nerves or their branches join and divide again
and again, interchanging and intermixing their fibres so thoroughly that,
by the time a branch leaves the plexus, it may contain fibres from all the
nerves entering the plexus. Still, as in the more simple communications
already spoken of, the fibres, so far as is known, remain individually distinct
throughout.
Some farther circumstances remain to be noticed as to the course of the fibres in
nerves and nervous plexuses.
Gerber has described and figured nerve-fibres, which, after running a certain way
in a nerve, apparently join in form of loops with neighbouring fibres of the same
bundle, and proceed no further. Such loops might of course be represented as
formed by fibres which bend back and return to the nervous centre ; and so Gerber
considers them. He regards them as looped terminations of sentient fibres appro-
priated to the nerve itself as the nervi nerrorum, in short, on which depends the
sensibility of the nerve to impressions, painful or otherwise, applied to it elsewhere
than at its extremities. The whole matter is, however, involved in doubt : for,
admitting the existence of the loops referred to, which yet requires confirmation, it
is not impossible that they may be produced by fibres which run back only a certain
way, and then, entering another bundle, proceed onwards to the termination of the
nerve. Again, it has been supposed, that, in some instances of nervous conjunc-
tions, certain collections of fibres, after passing from one nerve to another, take a
retrograde course in that second nerve, and, in place of being distributed periphe-
rally with its branches, turn back to its root and rejoin the cerebro-spinal centre.
An apparent example of such nervous arches without peripheral distribution is
afforded by the optic nerves, in which various anatomists admit the existence of
arched fibres that seem to pass across the commissure between these nerves from
one optic tract to the other, and to return again to the brain. These, however, are
perhaps to be compared with the commissural fibres of the brain itself, of which
there is a great system connecting the symmetrical halves of that organ. But
instances of a similar kind occurring in other nerves have been pointed out by
Volkmann ; as in the connection between the second and third cervical nerves of
the cat, also in that of the fourth cranial nerve with the first branch of the fifth in
other quadrupeds, and in the communications of the cervical nerves with the spinal
accessory and the descendens noni. But certain fibres of the optic nerves take a
course deviating still more from that followed generally, for they appear to be con-
tinued across the commissure from the eyeball and optic nerve of one side to the
opposite nerve and eye, without being connected with the brain at all, and thus to
form arches with peripheral terminations, but no central connection. In looking,
however, for an explanation of this arrangement, it must be borne in mind that the
retina contains nerve-cells, like those of the nervous centres, and perhaps the fibres
referred to may be intended merely to bring the collections of nerve-cells of the two
sides into relation independently of the brain. Julius Arnold has found an arrange-
ment of fibres at the junctions of the nerve-plexus of the iris similar to that in the
optic commissure.*
The disposition of the fibres at the points of division and junction of the branches
* Virchow's Arch. 1863.
ROOTS OF NERVES. cxlvii
of nerves still requires further investigation. For some interesting observations on
the subject the reader is referred to a paper by Dr. Beale.*
Origins or Roots of the Nerves. The cerebro- spinal nerves, as already
said, are connected by one extremity to the brain or to the spinal cord, and
this central extremity of a nerve is, in the language of anatomy, named its
origin or root. In some cases the root is single, that is, the fuiiiculi or
fibres by which the nerve arises are all attached at one spot or along one
line or tract ; in other nerves, on the contrary, they form two or more
separate collections, which arise apart from each other and are connected
with different parts of the nervous centre, and such nerves are accordingly
said to have two or more origin* or roots. In the latter case, moreover,
the different roots of a nerve may differ not only in their anatomical
characters and connections, but also in function, as is well exemplified in
the spinal nerves, each of which arises by two roots, an anterior and a
posterior the former containing the motory fibres of the nerve, the latter
the sensory.
The fibres of a nerve, or at least a considerable share of them, may be
traced to some depth in the substance of the brain or spinal cord, and hence
the term " apparent or superficial origin " has been employed to denote the
place where the root of a nerve is attached to the surface, in order to dis-
tinguish it from the "real or deep origin" which is beneath the surface and
concealed from view.
To trace the different nerves back to their real origin, and to determine
the points where, and the modes in which their fibres are connected with
the nervous centre, is a matter of great difficulty and uncertainty ; and,
accordingly, the statements of anatomists respecting the origin of particular
nerves are in many cases conflicting and unsatisfactory. Confining our-
selves here to what applies to the nerves generally, it may be stated, that
their roots, or part of their roots, can usually be followed for some way be-
neath the surface, in form of white tracts or bands distinguishable from the
surrounding substance ; and very generally these tracts of origin may be
traced towards deposits of grey nervous matter situated in the neighbour-
hood ; such, for instance, as the central grey matter of the spinal cord, the
grey centres of the pueiuno-gastric and glo.-so-pharyngeal nerves, the corpora
geniculata and other larger grey masses connected with the origin of the
optic nerve. It would further seem probable that certain fibres of the nerve-
roots take their origin in these local deposits of grey matter, whilst others
become continuous with the white fibres of the spinal cord or encephalon,
which are themselves connected with the larger and more general collections
of grey matter situated in the interior or on the surface of the cerebro-
spinal centre.
There is still much uncertainty as to the precise mode in which the nerve-
fibres originating or terminating in the grey matter are related to its ele-
ments, and for the most parb, indeed, individual tibres on being traced into
the grey matter, become so hidden in the mass as to elude further scrutiny.
Nevertheless, as a continuity between the nerve-fibres and nerve-cells in the
grey matter has now been traced in individual examples by many different
observers, and as such connections may be held to be general in the
ganglions, it is not unfair to infer that, but for the obstacles to successful
investigation, the cells in the grey matter of the cerebro spinal centre would by
this time also have been shown to be generally connected with the nerve-fibres.
* On the Branching of Nerve-Trunks, &c., Archives of Medicine, vol. iv. p. 127.
cxlviii KEKVOUS SYSTEM.
Three modes of connection of cells with fibres are described. 1. From a cell,
which may have several branched outrunners, one stout unbranched process is con-
tinued into a nerve-fibre, at first naked, and probably representing only the axis-
cylinder, then acquiring a medullary sheath and dark borders, and finally a mem-
branous tube or primitive sheath. 2. From one or more finely divided branches of
a cell, or of more than one cell, equally fine fibrils are prolonged, which coalesce
into a pale fibre, having the characters of an axis-cylinder, which then, as in the
former case, may in its progress become a dark-bordered medullated fibre. 3. The
extreme ramifications of a cell or cells become connected, as in the last case, with
fibrils, which join into a nerve-fibre ; but the connection takes place by the inter-
vention of small bipolar cells, which are by one pole continuous with the branches
of the larger cell or cells, and by the other with fine fibrils which join into a pale fibre,
or into an axis-cylinder of a dark-bordered fibre. Gerlach, and after him Waldeyer
and others, have described this last mode of connection, as seen by them in the
cerebellum. In the cortical grey matter of the cerebellum there are well known
large cells generally with one undivided process directed centrally, and two or three
finely divided branches towards the surface (fig. LXXIX.). Scattered in the neighbour-
hood of these large cells, and also collected in a layer named the stratum ferrugineum,
or rust-coloured layer, are numerous small cells, often called granules (fig. LXXX. c) ;
and it is alleged by the above named authorities that fine ramifications of the large
cells join neighbouring small cells or pass inwards to join those of the stratum
ferrugineum, and that the small or intermediate cells are, on the other hand, con-
nected with filaments which coalesce into nerve-fibres as above described. This
statement derives support from the important observations of Mr. Lockhart Clarke,
on the structure of the olfactory bulb. Along with this indirect connection through
small intervening cells, Gerlach supposes that a process or processes of the large cells
pass directly into nerve-fibres ; and should such direct connection take place by the
prolongation of an unbranched cell-process into a nerve-fibre, the arrangement would
be analogous to that in the ganglia ; the simple origin, representing that of the
straight fibre from the ganglion-cell, whilst the ramified origin, with the intervening
small cells, might be compared to that of the superficial or spiral fibre, with its
interposed nuclei.
The fibres of origin of a nerve, whether deeply implanted or not, on
quitting the surface of the brain or spinal cord to form the apparent origin
or free part of the root, are in most cases collected into funiculi, which are
each invested with a sheath of neurilemma. This investment is generally
regarded as a prolongation of the pia mater, and in fact its continuity with
that membrane may be seen very plainly at the roots of several of the
nerves, especially those of the cervical and dorsal nerves within the verte-
bral canal, for in that situation the neurilemma, like the pia mater itself, is
much stronger than in the cranium. The funiculi, approaching each other
if originally scattered, advance towards the foramen of the skull or spine
which gives issue to the nerve, and pass through the dura mater, either in
one bundle and by a single aperture, or in two or more fasciculi, for which
there are two or more openings in the membrane. The nerve roots in their
course run beneath the arachnoid membrane, and do not perforate it on
issuing from the cranio-vertebral cavity ; for the loose or visceral layer of
the arachnoid is prolonged on the nerve and loosely surrounds it as far as
the aperture of egress in the dura mater, where, quitting the nerve, it is
reflected upon the inner surface of the latter membrane, and becomes con-
tinuous with the parietal or adherent layer of the arachnoid. The nerve,
on escaping from the skull or spine, acquires its external, stout, fibrous
sheath, which connects all its funiculi into a firm cord, and then, too, the
nerve appears much thicker than before its exit. The dura mater accom-
panies the nerves through the bony foramina, and becomes continuous with
their external sheath and (at the cranial foramina) with the pericranium ;
TERMINATION OF NERVES. cxlix
but the sheath does not long retain the densely fibrous character of the
membrane with which it is thus connected at its commencement.
The arrangement of the membranes on the roots of certain of the cranial nerves
requires to be specially noticed.
The numerous fasciculi of the olfactory nerve pass through their foramina almost
immediately after springing from the olfactory bulb, and then also receive their
neurilemma. The bulb itself, and the intracrauial part of the nerve, which are to be
regarded as being really a prolongation or lobe of the brain, are invested externally
by the pia mater, but are not fasciculated. The arachnoid membrane passes over
the furrow of the brain in which this part of the nerve lies, without affording it a
special investment.
The optic nerve becomes subdivided internally into longitudinal fasciculi by neu-
rilemma a little way in front of the commissure : on passing through the optic
foramen it receives a sheath of dura mater, which accompanies it as far as the eye-
ball. The acoustic nerve becomes fasciculated, receives its neurilemma, and acquires
a firm structure on entering the meatus auditorius internus in the temporal bone,
towards the bottom of which it presents one or more small ganglionic swellings con-
taining the characteristic cells. Up to this point it is destitute of neurilemma, and
of soft consistence, whence the name " portio mollis " applied to it.
The larger root of the fifth pair acquires its neurilemma and its fasciculated cha-
racter sooner at its circumference than in the centre, so that, in the round bunch of
cords of which it consists, those placed more outwardly are longer than those within,
and, when all are pulled away, the non-fascicular part of the nerve remains in form of
a small conical eminence of comparatively soft nervous substance.
Most of the nerves have ganglia connected with their roots. Thus, the
spinal nerves have each a ganglion on the posterior of the two roots by
which they arise ; and in like manner several of the cranial, viz., the fifth,
seventh, glosso-pharyngeal, and pneumo-gastric, are furnished at their
roots, or at least within a short distance of their origin, with ganglia which
involve a greater or less number of their fibres, as described elsewhere in
the special anatomy of those nerves.
Termination, or peripheral distribution, of nerves. It may be stated,
generally, and apart from what may apply to special modes of termination,
that, in approaching their final distribution, ihe fibres of nerves, medullated
and non-medullated, commonly divide into branches (fig. LXXXV) ; and the
former, either before or after division, generally lose their medullary
sheath, and consequently their dark borders, and take on the characters of
pale fibres. The axis-cylinder participates in the division, and it might be
said that the white fibres are represented in their further progress by the
axis-cylinder and its ramifications ; still, the primitive sheath or mem-
branous tube continues some way along these pale branches after the medul-
lary sheath has ceased, but may finally too desert them. By repeated division
the fibres become smaller arid smaller ; but whilst some of the resulting small
fibres may be simple, many are really bundles of exquisitely fine pale fibrils,
straight, sinuous, or somewhat tortuous in their course. They bear nuclei,
some of which, no doubt, may appertain to the prolongation of the primitive
sheath ; but others, generally fusiform and granular, are interposed, as it were,
in the course of the fibres, and are continuous with them at either end ;
nuclei, moreover, of a triangular or irregular shape, are common at the
bifurcations of the fibres. These pale fibres often join into networks ; but
their further disposition in different parts will be treated of below. In
the meantime it must be explained that the original dark-bordered fibres
which thus undergo division and change, or which may proceed singly to
end in a different and special manner, are commonly provided with a
tolerably strong sheath with nuclei, which, as it stands well apart from
cl NERVOUS SYSTEM.
the dark borders of the fibre, is very conspicuous. This is sometimes
considered to be only the primitive sheath of the fibre modified in character,
Fig. LXXXV.
Fig. LXXXV. SMALL BRANCH OP A MUSCULAR NERVE OP THE FROG, NEAR ITS TERMI-
NATION, SHOWING DIVISIONS OP THE FlBRES.
a, into two ; b, into three ; magnified 350 diameters. (From Kolliker. )
but it seems more probable that it is derived from the neurilemma or peri-
neurium which incloses the fine bundles or funiculi, and, as these part into
smaller collections and single fibres, undergoes a corresponding division, aud
finally sends sheaths along single fibres.
In further treating of the terminations of nerves, it will be convenient to consider
the sensory and motor nerves separately.
Of the sensory, or, at least, non-muscular nerves, the following modes of final dis-
tribution have been recognised.
A. By networks, or terminal plexuses. These are formed by the branching and
inter] unction of the pale fibres above described. The meshes of the net may be at
first wider, and the threads, or bundles of threads, larger, but from these, finer fila-
ments forming closer reticulations proceed, and then sometimes the nuclei become
less frequent, or disappear. Such networks are found in the skin of the frog, rat, and
mouse; in various parts of the mucous membranes, in the cornea, and also in the
connective tissue beneath serous membranes or between their layers in different parts
of which the mesentery of the frog affords a good example. In some of these cases
the nerve-fibres come into the vicinity of connective-tissue-corpuscles, but, so far as I
have been able to see, are not connected with them.
B. Sensory terminal organs. Three varieties of these are now recognised, viz.,
a., end-bulbs b., touch-corpuscles, and c., Pacinian bodies. These have so far a
common structure, that in all of them there is an inward part or core (Innenkolben
Germ. ) of soft, translucent, finely granular matter ; an outer capsule of ordinary connec-
tive tissue with its pertaining corpuscles ; and, finally, one or sometimes more nerve-
fibres, pale and without dark contours, which pass into the core and apparently end
with a free, usually somewhat swollen, or knobbed extremity. Thus agreeing in
their internal and probably essential structure, the terminal organs differ chiefly, or
at least most obviously, in their capsule, which, simple in the end-bulbs, becomes
TERMINAL ORGANS.
cli
Fi2. LXXXVI.
highly complicated in the Pacinian bodies ; and therefore in the further account of
them it will be convenient to begin with the former, although the Pacinian bodies
have been much longer known.
a. End-bulbs. Noticed incidentally by Kblliker, but
first investigated and recognised as distinct organs by
W. Krause, who named them Endkolben. Their figure
in man and apes is usually spheroidal (fig. LXXXVI),
but oblong in some quadrupeds. They measure about
gigth of an inch in diameter, but may exceed this in
length with a less breadth, when of an oval shape.
They have a simple outer capsule of connective tissue,
bearing nuclei, and within this a core of clear soft
matter, in which specks resembling fat-granules become
visible after exposure to a solution of soda. To an
end-bulb there proceeds usually one, but sometimes
two, or even three dark-bordered nerve-fibres ; and
sometimes an originally single fibre divides into two or
three immediately before entering the corpuscle ; or
several branches of one fibre may each run into a sepa-
rate end-bulb. The fibre or fibres pass into the core, lose
their dark borders, and appear to end, when their ends
can be traced, in a bulbous extremity or knob. The
nerve-fibre, when about to enter the corpuscle, is often one nerve-fibre and fat-gra-
much coiled, and this may be the case too with its nules in the core. 3. Of an
pale continuation within, which contributes greatly to oval figure ; termination of
obscure its actual termination. End-bulbs have been
hitherto found in the conjunctiva over the sclerotic coat
of the eye, and in the mucous membrane on the floor
of the mouth, the lips, soft palate, and tongue, being in
these last-mentioned situations lodged in papillae, or at
their roots ; also, more deeply, in the skin of the glans of the penis and clitoris.*
Fig. LXXXVII.
Fig. LXXXVI. THREE
NERVE-END-BULBS FROM
THE HUMAN CONJUNCTIVA,
TREATED WITH ACETIC ACID,
MAGNIFIED 300 DIAMETERS.
1. With two nerve-fibres
forming coils within. 2. With
nerve distinct. Nuclei on
the capsules of 1 and 2.
(From Kb'lliker, after a draw-
ing by Liidden).
Fig. LXXXVII. END-BULBS IN PAPILLA, MAGNIFIED,
TREATED WITH ACETIC ACID.
A, from the lips ; the white loops in one of them
are capillaries. B, from the tongue. Two end-bulbs
seen in the midst of the simple papillae, a, a, nerves.
(From Kbllikev).
b. Touch-bodies, or tactile corpuscles (corpus-
cula tact&s). Discovered by R. Wagner and
Meissner. These are mostly of an oval shape, nearly
* W. Krause has lately described peculiar organs in the skin of the penis and clitoris,
allied to the end-bulbs, which he proposes to call genital nerve-corpuscles. They are
various in form, but present a mulberry-like surface. One, or two, rarely three or four,
dark-bordered nerve-fibres enter each of them. They have a delicate sheath of connec-
tive tissue, with many nuclei, and soft finely granular contents allied to the core of the
eud-bulbs.
I 2
of an inch long, and
clii
NERVOUS SYSTEM.
J~ of an inch thick. Within is a core of soft, transparent, homogeneous substance,
with sparsely imbedded granules; outside, a capsule of connective tissue, with
oblong nuclei directed transversely to the axis (and rendered more conspicuous
by acetic acid or coloration with carmine), which, -together perhaps with some hori-
zontally wound fibres, give the corpuscle somewhat the appearance of a miniature
fir-cone. One, two, or even more nerve-fibres, run to the corpuscle, and proceeding
straight, or with serpentine windings, approach the summit, up to this point retain-
ing their dark borders ; they then pass into the core, and, so far as can be seen, end
as fine pale fibres. The touch-corpuscles are found in the skin of the hand and foot,
and one or two other parts, where they are inclosed in certain of the cutaneous
papillas, which usually include no vessels. It may be here observed that loops of nerves
are sometimes seen in papillae without touch-bodies, but probably they belong to a
nerve on its way to end in the corpuscle of a neighbouring papilla.
Fig. LXXXV1II.
Pig. LXXXVIIT. PAPILLA PROM THE SKIN OP THE HAND, FREED FROM THE CUTICLE
AND EXHIBITING THE TACTILE CORPUSCLES. MAGNIFIED 350 DIAMETERS.
A. Simple papilla with four nerve-fibres, a, Tactile corpuscle ; b, nerves. B. Papilla
treated with acetic acid ; a, cortical layer with cells and fine elastic filaments ; 6, tactile
corpuscle with transverse nuclei ; c, entering nerve with neurilemma or perineurium ;
d, nerve-fibres winding round the corpuscle, c. Papilla viewed from above so as to appear
as a cross section, a, cortical layer ; 6, nerve-fibre ; c, sheath of the tactile corpuscle
containing nuclei ; d, core (after Kolliker).
c. Pacinian bodies. In dissecting the nerves of the hand and foot, certain small
oval bodies like little seeds, are found attached to their branches as they pass through
the subcutaneous fat on their way to the skin ; and it has been ascertained that each
of these bodies receives a nervous fibre which terminates within it. The objects
referred to were more than a century ago described and figured by Vater,* as
attached to the digital nerves, but he did not examine into their structure, and his
account of them seems not to have attracted much notice. Within the last few years,
their existence has been again pointed out by Cruveilhier and other French anato-
mists, as well as by Professor Pacini of Pisa, who appears to be the first writer that
has given an account of the internal structure of these curious bodies, and clearly
demonstrated their essential connection with the nervous fibres. The researches of
Pacini have been followed up by Henle and Kolliker, f who named the corpuscles
after the Italian savant ; and to their memoir, as well as to the article " Pacinian
Bodies/' by Mr. Bowman, in the " Cyclopaedia of Anatomy," and to more recent
* Abr. Vater, Diss. de Consensu Partium Corp. hum. ; Vitemb. 1741, (recus. in
Halleri Disp. Anat. Select, torn, ii.) Ejusd. Museum Anatomicum ; Helmst. 1750.
t Ueber die Pacinischen Korperchen ; Zurich, 1844,
PACIXIAN BODIES.
cliii
Fig. LXXXIX.
papers by "W. Krause* and Engelmann,f the reader is referred for details that cannot
be conveniently introduced here.
The little bodies in question (fig. LXXXIX) are, as already said, attached in great
numbers to the branches of the nerves of the hand and foot, and here and there one
or two are found on other cutaneous nerves. They have
been discovered also within the abdomen on the nerves of
the solar plexus, and they are nowhere more distinctly seen
or more conveniently obtained for examination, than in
the mesentery and omentum of the cat. between the layers
of which they exist abundantly. They have been found on
the pudic nerves in the glans penis and bulb of the urethra,
on the intercostal nerves, sacral plexus, cutaneous nerves
of the upper arm and neck, and on the infraorbital nerve.
Lately they have been recognised on the periosteal nerves,
and, in considerable numbers, on the nerves of the joints.
They are found in the foetus, and in individuals of all ages.
The figure of these corpuscles is oval, somewhat like that
of a grain of wheat, regularly oval in the cat, but mostly
curved or reniform in man, and sometimes a good deal dis-
torted. Their mean size in the adult is from i to i
of an inch long, and from i to i of an inch broad.
They have a whitish, opaliae aspect : in the cat's mesen-
tery they are usually more transparent, and then a white
line may be distinguished in the centre. A slender stalk
or peduncle attaches the corpuscle to the branch of nerve
with which it is connected. The peduncle contains a
single tubular nerve-fibre ensheathed in filamentous con-
nective tissue, with one or more fine blood-vessels ; and it
joins the corpuscle at or near one end, and conducts the
nerve-fibre into it. The little body itself, examined under
the microscope, is found to have a beautiful lamellar struc-
ture (fig. xc, A). It consists, in fact, of numerous concen-
tric membranous capsules incasing each other like the
coats of an onion, with a small quantity of pellucid fluid
included between them. Surrounded by these capsules, and
occupying a cylindrical cavity in the middle of the corpuscle, is the core, formed of
transparent and homogeneous soft substance, in the midst of which the prolonga-
tion of the nerve-fibre is contained. The number of capsules is various ; from forty
to sixty may be counted in large corpuscles. The series immediately following the
central or median cavity, and comprehending about half of the entire number, are
closer together than the more exterior ones, seeming to form a system by themselves,
which gives rise to a white streak often distinguishable by the eye along the middle
of the corpuscles when seen on a dark ground. Outside of all, the corpuscle has
a coating of ordinary connective tissue. The capsules, at least the more superficial
ones, consist each of an internal layer of longitudinal and an external of circular
fibres, which resemble the white fibres of areolar and fibrous tissue, with cell-nuclei
attached here and there on the inner layer, and a few branched fibres of the yellow or
elastic kind running on the outer. The nerve-fibre, conducted along the centre of the
stalk, enters the corpuscle, and passes straight into the central cavity, at the further
end of which it terminates.
The fibrous neurilemma surrounding the nerve-fibre in the peduncle accom-
panies it also in its passage through the series of capsules, gradually decreasing
in thickness as it proceeds, and ceasing altogether when the nerve has reached the
central cavity. According to Pacini, with whom Eeichert agrees in this particular,
the neurilemma forms a series of concentric cylindrical layers, which successively
become continuous with, or rather expand into the capsules, the innermost, of
course, advancing farthest. Others suppose that the capsules are all successively-
perforated by a conical channel which gives passage to the nerve with its neuri-
* Anat. Untersuchungen ; Hanover, 1861, and Zeits. f. rat. Med. xvii. 1805.
t Zeits. f. Wiss. Zool. xiii. 1863.
Fig. LXXXIX. A
NERVE OF THE MIDDLE
FINGER, WITH PACINIAN
BODIES ATTACHED. NA-
TURAL SIZE (after Henle
and Kolliker).
cliv
NERVOUS SYSTEM.
lemma, but at the same time has its own proper wall, round which, on the outside
the capsules are attached. Whichever view may be correct, the capsules are, as it
were, strung together where the nerve passes through them, and each intercapsular
space, with its contained matter, is shut off from the neighbouring ones. The
nerve-fibre, the disposition of which must now be noticed, is single as it runs along
Fig. XG.
Fig. XO. A, MAGNIFIED VIEW OP A PACINIAN BODY PROM THE MRSENTERY OP A CAT,
showing the lamellar structure, the capsules with their nuclei, the inner and closer series of
capsules appearing darker in the figure, the nerve-fibre passing along the peduncle, and
penetrating the capsules to reach the core in the central cavity, where it loses its strong,
dark outline, and terminates by an irregular knob at the distal and here dilated end of
the cavity. Connective tissue (neurilemma or perineurium) and blood-vessels are repre-
sented in the peduncle, and tortuous capillaries are seen running up among the capsules.
B and o represent the termination of the nerve with the distal end of the central cavity
and adjoining capsults, to illustrate varieties of arrangement. In B the fibre, as well as
the core and adjoining capsules, is bifurcated.
the peduncle, unless when the latter supports two corpuscles ; it retains its dark
double contour until it reaches the central cavity, where, diminished in size, and
freed from its perineurium, it becomes somewhat flattened, and presents the
appearance either of a pale, finely granular, and very faintly outlined band or
stripe, little narrower than the previous part of the fibre, or of a darker and more
sharply defined narrow line ; differing thus in appearance according as its flat side
or its edge is turned towards the eye. The pale aspect which the fibre presents in
the centre of the corpuscle has with some probability been ascribed to its losing the
white substance or medullary sheath on entering the cavity. Henle and Kolliker,
however, think that it is more likely the result merely of a diminution in size,
together with a certain degree of flattening. It sometimes happens that the fibre
regains its original magnitude and double contour for a short space, and changes
again before it terminates ; this is especially liable to occur while it passes through a
sharp flexure in a crooked central cavity. The fibre ends by a sort of knob at the
further extremity of the median cavity, which is often itself somewhat dilated. In
TERMINATION OF NERVES. civ
many cases, the fibre, before terminating, divides into two branches, as represented in
figure B : a division into three has been observed, but this is very rare. In case of
division of the fibre, the cavity is generally, but not invariably, divided in a corre-
sponding measure, and the inner set of capsules present a figure in keeping with it.
It is worthy of remark, that the nerve-fibre in its course along the cavity runs almost
exactly in the axis of the channel, and it maintains this position even when passing
through the abrupt flexures of an irregularly shaped cavity. It sometimes happens that
a fibre passes quite through one corpuscle and terminates in a second, resuming its
original size and dark outline while passing from the one to the other. Pappenheim
states that he has seen a nerve-fibre going through two Pacinian bodies without ter-
minating in either, but returning again to the parent nerve in form of a loop. Other
varieties occur, for an account of which the reader is referred to the several authorities
already mentioned. A little artery enters the Pacinian bodies along with the nerve,
and soon divides into capillary branches, which pierce the parietes of the passage and
run up between the capsules. Mr. Bowman finds that they then form loops, and
return by a similar route into a vein corresponding to the artery : he states also that
a single capillary usually accompanies the nerve as far as the central capsule, and
passes some way on its wall, sometimes in a spiral direction.
There is considerable difference of opinion as to the condition of the nerve-fibre in
the Pacinian body. Kolliker thinks that it retains its primitive sheath, and is not
wholly deprived of its medulla ; and that the surrounding core is composed of a
nearly homogeneous connective tissue, in which he has seen faintly marked nuclei
and faint longitudinal striation. Engelmann, on the other hand, considers the core
to be an expansion of the medullary sheath of the nerve, and ascribes the appearances
noticed by Kolliker to changes occurring in the originally homogeneous medulla,
as in the case of a white nerve-fibre. The pale fibre within he considers to be simply
the axis-cylinder. The core and pale fibre of the end-bulbs he regards in precisely
the same way, and thinks it not improbable that the touch-corpuscles will be found
to conform. He looks upon the simple capsule of the end-bulb as a development of
the primitive nerve-sheath, to which, in the Pacinian bodies, is superadded a series of
concentric coats of connective tissue. Engelmann, besides adducing other arguments,
refers especially to the structure of the Paciniau bodies of birds, as affording material
evidence in support of his view.
Nothing positive is known concerning the special purpose in the animal economy
which these curious appendages of the nerves are destined to fulfil. In an anatomical
sense a Pacinian body might be viewed as a more complex development of an end-
bulb, from which it differs chiefly in the multiplied layers of the capsule. W. Krause
endeavours to show that the series of concentric capsules with interposed fluid is an
arrangement for converting the effect of mechanical traction into fluid pressure upon
the nerve, so that tension and traction of the tissue in which the corpuscle is placed,
may be felt and appreciated as ordinary pressure. Their presence in the mesentery
of the cat seems, at first sight, against their importance as sentient organs, but it
turns out upon trial, that the part in question is remarkably sensitive.
C. Other terminations of sensory nerves.
a. In hair-follicle*. By far the majority of the nerves of the skin end in hair-
follicles. Up to their entrance, at least, they retain their dark borders, but their
arrangement within and actual mode of termination arc unknown.
b. In the teeth. Dark bordered nerve-fibres, in fine bundles, enter the teeth and
pass into the tooth-pulp ; but their mode of termination has not been clearly made out.
c. In organs of special sense. For the peripheral distribution of the optic and
acoustic nerves, and the elaborate apparatus in the eye and ear with which they
are connected, the reader is referred to the details given in the special anatomy
of these organs. Respecting the more simple termination of the olfactory nerve,
it has been shown by Max Schultze, that on the olfactory membrane, alongside
columnar epithelium cells, there are special nucleated cells of a fusiform shape,
and probably of a nervous nature (olfactory cells), from which proceed a superficial
and a deep process, often presenting a beaded appearance like varicose nerve-fibres.
The superficial processes end abruptly at the surface of the epithelium between the
columnar cells ; the deep and more slender processes pass vertically inwards. They
are probably continued from terminal fibres of the olfactory nerve, but the continuity
has not been actually traced.
clvi NERVOUS SYSTEM.
An analogous arrangement is described by Axel Key~as discoverable in the fungi-
form papillae of the frog's tongue. Among non-ciliated columnar epithelium cells
are fusiform gustatory cells, having, like the olfactory cells, fine rod-like processes
reaching to the surface, and slender, varicose, central filaments, which seem to be
continuous with pale fibrils, into which the axis-cylinder of the gustatory nerve-
fibres finally divides ; and in such way that one axis-cylinder may be connected with
several cells.
d. In epithelium. Hoyer believes he has seen fine, pale filaments continued from
the plexus of the cornea into the epithelium covering its anterior surface, where they
appeared to pass between the cells. Von Heusen de-scribes and figures exquisitely
fine filaments connected with the nucleoTi of epithelium cells on the tadpole's tail.
He finds evidence to satisfy him that their filaments are continued from the cutaneous
nerves, which he therefore conceives to run out into epithelium cells as their terminal
organs, and end in the nucleoli.
e. In glands. The termination of nerves in secreting glands will be most conve-
niently given in the account of the structure of these organs. In the meantime it
may be stated that Pfliiger has traced nerve-fibres to the nuclei of the cells which line
the terminal saccules of the salivary glands.
Termination of nerves in muscles :
A. In plain or unstriped muscle. Dr. Beale, and, after him, Dr. Klebs, have
described the nerves of the muscular coat of the frog's bladder as finally distributed in
networks of pale fibres, with nuclei. The networks are at first coarser, with larger
grey fibres made up of coalesced fibrils (fibrillar fibres), and from these proceed finer
bundles and single fibrils, forming closer reticulations, constituting the intramuscular
plexus, which is disposed among the muscular fasciculi and fibre-cells. A more inti-
mate relation to the latter could not be traced with certainty, although Klebs met
with a single instance of a nerve-fibril entering a muscular fibre-cell. The nerves
distributed to the middle or muscular coat of the arteries are, according to Beale, dis-
posed in a similar plexiform manner ; and Julius Arnold has since found a terminal
pale nervous network of the same kind in the iris of the rabbit.
B. In voluntary muscle, a. By plexuses. As mentioned in the account of the
muscular tissue, the nerves in the voluntary muscles form plexuses, of which the
branches grow finer and the meshes closer as they advance further into the tissue.
The individual fibres, while still associated in small bundles, undergo division (fig.
LXXXV), and at length single dark-bordered fibres pass off to the muscular fibres.
These nerve-fibres on approaching or reaching a muscular fibre divide still further.
As to their ulterior and final distribution, there is great divergence in the statements
of very able observers. Beale and Kb'lliker agree in opinion that the fibres lose their
dark borders and run further on as pale fibres, which do not penetrate the sarcolemma.
Dr. Beale describes the pale fibres, in the mouse and frog, as distributed in a fine
network, bearing nuclei, adhering to, but outside, the sarcolemma, and extending over
a great length of the muscular fibre. Kb'lliker, whose observations were made on the
frog, found the fibres apparently to terminate by free ends ; at the same time, having
seen, here and there, indications, although imperfect, of a fine network, such as he had
observed in the electric organ of the torpedo, he is not disposed to exclude the possi-
bility of such mode of termination.
b. By terminal organs. Since the publication of Beale and Kblliker's observations,
a very different account has been given by Eouget namely, that the muscular nerves
end in peculiar terminal organs, which have been named the motorial end-plates, to
be seen on the muscular fibres, and his account has been in the main confirmed by
various contemporary observers, although some important authorities still hold to a
different view. The end-plates are described as small lamelliform objects, of an oval
or irregular, and often deeply indented outline ; their size varies from ^gg to ^ of
an inch, according to the size of the muscular fibre, of which the plate may embrace
one-third, or more, of the circumference. There is a question whether these organs are
situated without or within the sarcolemma. W. Krause, who adopts the former view,
describes the end-plate as consisting of a thin lamina of connective tissue, attached by its
oval or irregular border to the sarcolemma, with clear non-granular nuclei in it, and a
finely granular matter underneath, between it and the sarcolemma, in which the axis-
cylinder of the nerve-fibre ends, in form of one, or sometimes more, short pale fibres, with
free and swollen extremities; whilst the medullary sheath ceases, and the primitive sheath
DIFFERENCES OF CEREBRO-SPINAL NERVES. clvii
is continued into the covering lamina of connective tissue. On the other hand,
Rouget, Kuhne, and most of those who have given descriptions of the organs in ques-
tion, maintain that the end-plate is within the sarcolemma, interposed between it
and the proper muscular substance. According to their descriptions, the ultimate
nerve-fibre, on reaching the muscular fibre, either immediately or after running but
a short way on the surface, sends its axis- cylinder through the sarcolemma to spread
out into the plate, whilst the primitive (or perhaps perineural) sheath joins the sarco-
lemma, and the medullary sheath, which continues on the still dark bordered fibre up
to this point, here abruptly ceases. The proper substance of the plate, usually lobed
at its circumference (Kuhne), is continuous with the axis-cylinder, and is mostly held
to be an expansion of it, for it is said to have the same homogeneous or, at most,
faintly granular aspect, and to agree with it in optical and micro-chemical characters.
Around and beneath this lamina is a bed of granular matter, with large imbedded
nuclei having one or more bright nucleoli. The sarcolemma over the seat of the end-
plate, and the plate itself, are slightly raised above the general surface, so that the
whole structure has been designated by Kiihne as the nerve-eminence (Nerven-hiigel).
It would appear that a muscular fibre has but one terminal organ, and receives con-
sequently but one nerve-fibre, so that, allowing the muscular fibre to be one inch and
a half long, a considerable length must be governed by one terminal nerve-fibre. As,
moreover, the fibres of a nerve undergo division, probably repeated division, before
ending, it follows that one fibre in a nerve-root or trunk may supply several muscular
fibres. The motorial end-plates have now been recognised in mammalia, birds, and
scaly reptiles, and, in a modified form, in various invertebrata. *
Differences of cerebro spinal Nerves. It remains to notice the differences
which have been observed among the cerebro-spinal nerves in regard to the
size of their fibres, and the proportionate amount of the different kinds of
fibres which they respectively contain.
As already stated, both white and grey fibres exist in cerebro-spinal nerves, and those
of the former kind differ greatly from each other in size. Volkmann and Bidder, who
have bestowed much pains in endeavouring to arrive at an approximate estimate of
the relative amount of the large and the small fibres in different nerves, give the fol-
lowing as the more important results of their researches.
1. The nerves of voluntary muscles have very few small fibres, usually in not larger
proportion than about one to ten.
2. In the nerves of involuntary muscles, whether derived immediately from the
cerebro-spinal system or from the sympathetic, the small fibres eminently preponde-
rate, being about a hundred to one.
3. The nerves going to the integuments have always many small fibres, at least as
many small as large.
4. Nerves of sentient parts of mucous membranes have from five to twenty times
more small fibres than large : in mucous membranes possessing little sensibility, the
nerves are made up chiefly of small fibres. The nerves distributed in the pulp of the
teeth consist principally of large fibres.
It is plain, however, that Volkmann and Bidder must have reckoned in with their
small fibres more or fewer of the non-medullated sort, so that the proportion assigned
to the small fibres in their estimate must be taken as including some grey, as well as
white fibres; and this agrees with the observation previously made by Remak, that
many more grey fibres are contained in the cutaneous than in the muscular nerves.
The roots of the spinal nerves contain fine fibres, but according to Remak only in
very small proportion : Volkmann and Bidder state that in man the anterior roots
contain proportionally more large fibres than the posterior. In almost all nerves, the
fibres diminish in size as they approach their termination.
The fibres of the optic nerve for the most part resemble the white fibres of the
brain, and readily become varicose. The same is true of the acoustic nerve, from its
* For further information on the termination of the nerves, see the Croonian Lectures,
by Professor Kolliker, Proceedings of the Royal Society, 1362, and by Dr. Beale, ibid.,
1865 ; also a discussion of the question by Dr. B. in his " Archives of Medicine" for
1865.
clviii NERVOUS SYSTEM.
origin to its entrance into the internal auditory foramen, where it becomes fascicu-
lated ; also of the intracranial part of the olfactory, which, however, contains in addi-
tion grey matter and nerve-cells, and may, indeed, be reckoned as part of the brain.
The branches of the olfactory in the nose are almost wholly made up of fibres bearing
nuclei, and having all the outward characters of the grey fibres, like which, also, they
cohere or cling fast together in the bundles which they form. Some branches seem
to consist entirely of such fibres ; others contain a few white fibres intermixed, which,
however, may be derived from the nasal branches of the fifth pair.
OF THE SYMPATHETIC OB GANGLIONIC NERVE.
This name is commonly applied to a nerve or system of nerves present on
both sides of the body, and consisting of the following parts, viz. 1. A
series of ganglia, placed along the spinal column by the side of the vertebrae,
connected with each other by an intermediate nerve-cord, and extending
upwards to the base of the skull and downwards as far as the coccyx. This
principal chain of ganglia, with the cord connecting them, forms what is
often named the trunk of the sympathetic. 2. Communicating branches,
which connect these ganglia or the intermediate cord with all the spinal and
several of the cranial nerves. 3. Primary branches passing off from the
ganglionic chain or trunk of the nerve, and either bestowing themselves at
once, and generally in form of plexuses, on the neighbouring blood-vessels,
glands, and other organs, or, as is the case with the greater number, pro-
ceeding in the first instance to other ganglia of greater or less size (some-
times named prevertebral) situated in the thorax, abdomen, and pelvis,
and usually collected into groups or coalescing into larger gaugl ionic masses
near the roots of the great arteries of the viscera. 4. Numerous plexuses
of nerves, sent off from these visceral or prsevertebral ganglia to the viscera,
usually creeping along the branches of arteries, and containing in various
parts little ganglia disseminated among them. Some of these plexuses also
receive contributions from spinal or cerebral nerves, by means of branches
which immediately proceed to them without previously joining the main
series of ganglia.
Structure of the sympathetic nerve. The nervous cords of the sympathetic
consist of white fibres, and of pale or grey fibres mixed with, a greater or
less amount of filamentous connective tissue, and inclosed in a common ex-
ternal fibro-areolar sheath. The white fibres differ greatly from each other
in thickness. A few are of large size, ranging from - ^^ to -jj^-^ of an
inch : but the greater number are of much smaller dimensions, measuring
from about 8 Vo o" to i^VtT ^ an * uc h * n diameter, and, though having a
well-defined sharp outline, for the most part fail to present the distinct
double contour seen in the larger and more typical examples of the tubular
fibre. The pale, non-medullated fibres, have partly the characters of
Remak's grey fibres, already described, and often look as if they were really
made up of exquisitely fine fibrils ; but there are also pale fibres of much
less thickness, which, at t-hort distances, are interrupted by, or might be
said to swell out into, fusiform nuclei.
The more grey-looking branches or bundles of the sympathetic consist of
a large number of the pale fibres mixed with a few of the dark-bordered
kind : the whiter cords, on the other hand, contain a proportionally large
amount of white fibres, and fewer of the grey ; and in some parts of the
nerve grey fasciculi and white fasciculi, respectively constituted as above
described, run alongside of each other in the same cords for a considerable
space without mixing. This arrangement may be seen in some of the
branches of communication with the spinal nerves, in the trunk or cord
SYMPATHETIC ]S T ERYE. clix
which connects together the principal chain of ganglia, and in the primary
branches proceeding from thence to the viscera. In the last-mentioned
case the different fasciculi get more mixed as they advance, but generally it
is only after the white fasciculi have passed through one or more ganglia that
they become thoroughly blended with the grey ; and then, too, the nervous
cords receive a large accession of grey fibres (apparently derived from the
ganglia), which are mixed up with the rest, and take off more and more
from their whiteness.
Relation of the sympathetic to the cerebro-spinal nerves. "We have next
shortly to consider the relation between the sympathetic and the cerebro-
spinal system of nerves. On this important question two very different
opinions have long existed, in one modification or another, amongst ana-
tomists. 1. According to one, which is of old date, but which has lately
been revived and ably advocated by Valentin, the sympathetic nerve is a
mere dependency, offset, or embranchment of the cerebro- spinal system of
nerves, containing no fibres but such as centre in the brain and cord,
although it is held that these fibres are modified in their motor and sensory
properties in passing through the ganglia in their way to and from the
viscera and involuntary organs. 2. According to the other view, the sym-
pathetic nerve (commonly so called) not only contains fibres derived from
the brain and cord, but also proper or intrinsic fibres which take their rise
in the ganglia ; and in its communications with the spinal and cranial
nerves, not only receives from these nerves cerebro- spinal fibres, but imparts
to them a share of its own proper ganglionic fibres, to be incorporated in
their branches and distributed peripherally with them. Therefore, accord-
ing to this latter view, the sympathetic nerve, commonly so called, though
not a mere offset of the cerebro- spinal nerves, yet, receiving as it does a
share of their fibres, is not wholly independent, and for a like reason the
cerebro spinal nerves (as commonly understood) cannot be considered as con-
stituted independently of the sympathetic ; in short, both the cerebro-spinal
and the sympathetic are mixed nerves, that is, the branches of each system
consist of two sets of fibres of different and independent origin, one con-
nected centrally with the brain and cord, the other with the ganglia. Hence,
if we look to the central connection of their fibres as the essential ground of
distinction among nerves, the cerebro-spinal system of nerves might, strictly
speaking, be considered as consisting of and comprehending all the fibres
having their centre in the cerebro-spinal axis, whether these fibres run in the
nerves usually denominated cerebral and spinal, or are distributed to the
viscera in the branches of the nerve usually named the sympathetic ; and,
on the same ground, the sympathetic or gangliouic system, strictly and pro-
perly so called, would consist of and comprehend all the fibres connected
centrally with the ganglia, wherever such fibres exist and into whatever
combinations they enter, whether proceeding to the viscera or distributed
peripherally with the nerves of the body generally ; the nerve-fibres which
emanate from the ganglia on the roots of the spinal and cerebral nerves
being reckoned into the system, as well as those from ganglia, visually deno-
minated sympathetic. While ready, however, to acquiesce in the justice of
the above distinction, we do not mean to employ the terms already in use
in a sense different from that which is currently received.
In endeavouring to decide between the two views above stated, it may be first
observed that the existence in the sympathetic nerve of fibres connected centrally with
the cerebro-spinal axis, is proved not only by tracing bundles of fibres from the roots
of the spinal nerves along the communicating branches and into the sympathetic, but
clx NERVOUS SYSTEM.
by the pain or uneasy sensations which arise from disease or disturbance of organs,
such as the intestines, supplied exclusively by what are considered branches of the
sympathetic ; by experiments on living or recently killed animals, in which artificial
irritation of the roots of the spinal nerves, or of various parts of the cerebro spinal
centre, caused movements of the viscera; and by experiments of the sympathetic
nerve in the neck, by which it is shown that the dilatation of the pupil and the tonicity
of the cutaneous vessels of the head are dependent on fibres which pass along the
sympathetic nerve but 'are centrally connected with the upper part of the spinal cord.
These facts, it is evident, accord with both of the above-mentioned opinions respect-
ing the constitution of the sympathetic ; but it may be further shown that this nerve
contains fibres which arise from the ganglia and take a peripheral course, so that the
second of the two opinions approaches nearer to the truth. In support of this assertion
we may adduce the actual observation of nerve-fibres proceeding from the nerve-cells
of the ganglia in a peripheral direction only ; and there are also other grounds for
believing that more fibres pass out of the sympathetic ganglia than can possibly be
derived from the brain and cord. This seems to follow from a comparison of the
aggregate size of the branches issuing from these ganglia with that of all the branches
which can be supposed to enter them. To explain this, however, we must first con-
sider the mode of communication between the sympathetic and spinal nerves.
The branches of communication which pass between the ganglia or gangliated cord
of the sympathetic and the spinal nerves, are connected with the anterior and greater
branch of each of the latter nerves, a little in advance of the spinal ganglion ;
and at the point of connection the communicating branch in most cases divides into
two portions, one central, running towards the roots of the spinal nerve and the spinal
cord, the other, peripheral, taking an outward course along with the anterior branch
of the spinal nerve, with which it becomes incorporated and distributed. It can
scarcely be doubted that the central portion, whilst it may contain fibres sent by the
sympathetic to the spinal nerves or to the spinal cord, must necessarily contain all
those which proceed from the cord to the sympathetic, and that, on the other hand,
the peripheral division must consist of fibres immediately proceeding from the sympa-
thetic and distributed peripherally with the spinal nerve. It is further observed, that
in some of the junctions with the spinal nerves, the central and peripheral divisions
of the communicating branch are about equal in size, and that in others the central
part is greater than the peripheral, whilst in others, again, the peripheral prevails over
the central. Now, in an animal such as the frog, in which the spinal nerves are of
small size and few in number, it is possible, with the aid of the microscope, to com-
pare by measurement the central and peripheral divisions of the communicating
branch in all the communications between the sympathetic and the spinal nerves, or
even to count the fibres when the branches are very fine ; and by such a comparison
Volkmann and Bidder have shown, that, after making all reasonable deductions and
allowances, the whole amount of the fibres, or at least the aggregate bulk of the
fasciculi, which obviously pass from the sympathetic and run outwards with the spinal
nerves, considerably exceeds that of the central fasciculi which must contain the fibres
contributed to the sympathetic from the cerebro-spinal system : and if to these peri-
pheral fibres we add the branches distributed to the viscera, it seems plain that more
fibres must proceed from the ganglia than can possibly be supposed to enter them
from the spinal nerves or spinal cord, and that consequently the ganglia must them-
selves be centres in which nerve-fibres take their rise. It is worthy of remark, that
in the frog, according to the observations of the anatomists just named, the central
division of the communicating cord greatly exceeds the peripheral in the connections
with the upper spinal nerves, but that lower down it gradually diminishes, absolutely
as well as in comparison with the peripheral, and at length disappears altogether, so
that the 'fasciculi connected with 'the eighth and ninth spinal nerves are entirely
peripheral in their course.
Another circumstance still remains to be noticed respecting the communications of
the sympathetic and spinal nerves. It has been long known that in most of these
communications there are usually two connecting cords passing between the sympa-
thetic and the spinal nerve ; and it has been remarked also by various observers, that
these cords contain grey as well as white fasciculi. More recently, however, Todd
and Bowman have called attention to the fact that one of the two connecting cords is
SYMPATHETIC NERVE. cbd
altogether of the grey kind, consisting of gelatinous fibres, with, as usual, a very few-
white or tubular fibres mixed with them ; and this observation has since been con-
firmed by Beck. The other cord either is entirely white, or more commonly, as
appears to me, is made up of a white and grey portion running alongside each other.
It seems highly probable that the white cords and the white fasciculi of the mixed
cords contain the cerebro-spinal fibres which the spinal nerves contribute to the sympa-
thetic, and that the grey cords and fasciculi are contributions from the sympathetic to
the spinal nerves. In corroboration of this view, Mr. Beck observes that the grey
cords on leaving the ganglia give small branches to the neighbouring vessels, and are
reduced in size before joining the spinal nerves. Another interesting fact respecting
these communications has been pointed out by the last-named observer somewhat
similar to that previously noticed in the frog, namely, that whilst the grey and white
connecting cords are in the thorax of nearly equal size, the grey one relatively increases
lower down, and in the pelvis constitutes the sole communication between the sacral
ganglia of the sympathetic and the spinal nerves, the white branches from the latter,
to the sympathetic passing over the sacral ganglia without joining them, to enter the
sympathetic plexuses sent to the pelvic viscera.
The tubular fibres of each white communicating fasciculus can be traced back to
both the anterior and the posterior root of the spinal nerve, and pale fibres from the
grey fasciculus may be traced up into the anterior root, and as far as the ganglion of
the posterior root, which root has also pale fibres above the ganglion. Whether these
central pale fibres proceed from the sympathetic to the spinal cord (possibly to be dis-
tributed to its vessels), or are sent from the cord and spinal ganglia to the sympathetic,
or pass both ways, is as yet uncertain.
As to the further progress of the cerebro-spinal fibres conveyed to the sympathetic
by the communicating branches, Valentin has endeavoured to show that, after joining
the main gangliated cord or trunk of the sympathetic, they all take a downward
direction, and after running through two or more of the ganglia, pass off in the branches
of distribution, leaving the trunk considerably lower down than the point where they
joined it. He conceives that this arrangement, which he calls " lex progresses," is
proved by experiments on animals, in which he found, that on irritating different
parts of the cerebro-spinal axis, as well as different branches of nerves, the visceral
movements which followed bore a relation to the point irritated, which corresponded
with the notion of such an arrangement. Volkmann and Bidder, on the other hand,
show that this opinion cannot be reconciled with the observed anatomical disposition
of the fibres, for there are fasciculi from the communicating branches which obviously
pass upwards ; nor will the experimental evidence in its favour apply to the upper
part of the sympathetic, where, as Valentin himself admits, motorial fibres must be
supposed to run in an upward direction to account for the contraction of the pupil
which follows section of the cervical part of the sympathetic.
From what has been stated, it seems reasonable to conclude that nerve-
fibres take their rise in the ganglia both of the cerebro-spinal and sympa-
thetic nerves, and are in both kinds of nerves mixed with fibres of cerebral
or spinal origin ; that the ganglia are nervous centres which may probably
receive through afferent fibres impressions of which we are unconscious and
reflect these impression al stimuli upon efferent or motor fibres : that per-
haps, even, certain motorial stimuli emanate from them, the movements ex-
cited by or through the ganglia being always involuntary, and affecting
chiefly the muscular parts of the viscera, the sanguiferous, and perhaps the
absorbent vessels ; and that, in fine, the chief purpose served in the animal
economy by the ganglia and the ganglionic nerve-fibres, whether existing in
acknowledged branches of the sympathetic, or contained in other nerves, is
to govern the involuntary, and, for the most part, imperceptible movements
of nutrition, in so far at least as these movements are not dependent on the
brain and spinal cord ; for it must not be forgotten that there is unques-
tionable evidence to prove that the visceral and vascular motions are influ-
enced by nerve-fibres connected with the csrebro-spinal centre.
clxii NERVOUS SYSTEM.
Among various physiologists of consideration, who adopt this view in a
more or less modified shape, some have been further of opinion that the
fibres of ganglionic origin differ iu structure, size, and other physical cha-
racters from those which arise in the cerebro-spinal axis. As regards this
question, I must confess, that there does not seem to me to be conclusive
evidence to show that peculiar anatomical characters are distinctive of the
fibres of different origin. It has been already stated that both dark-
bordered and pale fibres may be connected with ganglion-cells, and for auyht
that has been proved to the contrary, all three varieties of fibres spoken of,
large tubular, small tubular, and grsy, may arise both in the cerebro-spinal
axis and in the ganglia ; although it is certainly true that the two latter
kinds largely predominate in the sympathetic, and abound in other nerves, or
branches of nerves, which appear to receive large contributions from ganglia.
VITAL PROPERTIES OF THE NERVOUS SYSTEM.
The fibres of nerves are endowed with the property of transmitting im-
pressions, or the effect of impressions, from the point stimulated towards
their central or their peripheral extremities. One class of fibres conduct
towards the nervous centres and are named " afferent," their impressions
being " centripetal ; " another class of fibres conduct towards their distal
extremities, which are distributed in moving parts, arid these fibres are
named " efferent," whilst their impressions are " centrifugal." Impres-
sions propagated centripetally along the nerves to the brain give rise to sen-
sations, varying according to the nerve impressed, and the objective cause
of the impression ; stimuli transmitted outwardly, on the other hand, are
conveyed to muscles, and excite movements. Motorial stimuli thus passing
along efferent nervous fibres may emanate from the cerebrum as in volun-
tary and emotional movements, or possibly from some other central part, as
in the case of certain involuntary motions ; or such stimuli may be applied
in the first instance to afferent fibres, by these conducted to the brain or
some other central organ, and then " reflected " by the central organ to
efferent fibres, along which they are propagated to the muscle or muscles to
be moved ; and in this case the intervention of the central organ may give
rise to sensation or not, the difference in this respect probably depending on
the part of the nervous centre where the reflection takes place.
Ihe property of conducting a stimulus or propagating its effects in a deter-
minate direction, belongs to the fibres of the nerves, and in all probability
also to the fibrous part of the nervous centre, while it is probable that to
the cells or corpuscles of the grey matter of the central organs, is assigned
the office of receiving impressions conveyed from without, and presenting
them to the conscious mind, of mediating between the mind and the efferent
fibres in excitation of the latter by mental stimuli (as in voluntary and
emotional acts), of transferring to efferent fibres stimuli conducted to the
centre by afferent fibres in the production of reflex movements, and, pos-
sibly, of originating purely corporeal stimuli in certain involuntary motions.
In addition to these endowments, the nerves are concerned in controlling
and regulating the molecular changes and chemical actions which occur in
nutrition, secretion, and other allied processes. It may no doubt be fairly
questioned, whether the effect justly attributable to the nerves in such cases
is not produced merely through the influence which they exert over the
motions of the minute vessels and contractile tissues concerned ; but the
tendency of late observations on the nerves of secreting glands, and of the
experiments on the luminiferous organ of the fire -fly, referred to in a
DEVELOPMENT OF KERVES. clxiii
former chapter, is towards the recognition of some more direct opera-
tion.
The properties above mentioned, of the nerves and nervous centres, have
been commonly ascribe;! to a peculiar force developed in the nervous system,
which has received the names of "nervous force," "nervous principle,"
"nervous influence," and "vis nervcsa" (in the largest sense of that term) ;
and whilst some physiologists consider that force as a species of agency alto-
gether peculiar to living bodies, others have striven to identify it with some
of the forces known to be in operation in inanimate nature, or to show its
fundamental relationship to them.
The greater number of nerves possess both afferent and efferent fibres, and
are named compound or mote-sensory, inasmuch as they minister both to
sensation and motion. In such compound nerves the two kinds of fibres
are mixed together and bound up in the same sheaths ; but in the most
numerous and best-known examples of this class, the afferent and efferent
fibres, though mixed in the trunk and branches of the nerves, are separated
at their roots. This is the case in the spinal nerves : these have two roots,
an anterior and posterior, both for the most part consisting of many fuui-
culi, and the posterior passing through a ganglion with which the fibres of
the anterior root have no connection. Now it has been ascertained by ap-
propriate experiments on animals, that the anterior root is efferent and
contains the motor fibres, and that the posterior is afferent and contains the
sensory fibres. The fifth pair of cranial nerves has a sensory root furnished
with a ganglion, and a motor root, like the spinal nerves. The glosso-
pharyngeal and pneumo-gastric nerves are also decidedly compound in
nature ; they are also provided with ganglia at their roots, which involve a
greater or less number of their fasciculi ; but it has not yet been satisfac-
torily determined whether in these nerves the fibres which have different
properties are collected at the roots into separate bundles, nor how they are
respectively related to the ganglia. The sympathetic, as already stated,
contains both afferent and efferent fibres.
Simple nerves are such as contain either afferent or efferent fibres only.
The olfactory, auditory, and optic are simple afferent and sensory nerves.
The third, fourth, and sixth, the facial, the spinal accessory and hypoglossal
nerves are generally regarded as examples of simple motor nerves ; there is
reason to believe, at least, that they are simple and motor in their origin,
or as far as their proper fibres are concerned, and that the sensibility evinced
by some of them in their branches is owing to sensory fibres derived from
other nerves which join them in their progress.
The nerves governing the motions of the blood-vessels are commonly
spoken of as the " vaso-motorial nerves ; " but although this term is often
of convenient application, there seems no sufficient reason for reckoning
these nerves as a distinct system, any more than motorial nerves distributed
to other parts or organs whose motions are independent of the will.
DEVELOPMENT OF NERVES.
The knowledge as yet acquired respecting this process is not very positive or
consistent, so that much room is left for speculation and conjecture. The nerve-cells
are generally said to be derived from the common embryo-cells, which, undergoing
modification in their substance, send out branches from their circumference and
acquire the character of nerve-cells. As they are sometimes found with double or
divided nuclei, it is inferred that they increase in number by division, after the
manner of cells generally. According to the most generally current descriptions,
the fibres are stated to be formed by the linear coalescence of fusiform cells, and to
clxiv NERVOUS SYSTEM.
be at first pale and grey, but afterwards to acquire medulla and become white. This
change of aspect is apparent in the human embryo of the fourth or fifth month.
Harting considers that the fibres represent at first only naked axis-cylinders, and
suggests that the enclosing membranous tube and white substance are produced as
an excretion from the axial fibre. According to Kb'lliker's account of the growth of
nerve-fibres at their peripheral ends, as observed in the tail of batrachian larvae, the
existing fibres are prolonged by rows of fusiform cells which coalesce into pale fibres.
These send out fine offshoots, which may join with neighbouring fibres, or with
branched or stellate cells, which change into branched fibres, and in both of these
ways the branching and conjunction of the nerves go on. The first fibres thus gene-
rated (embryonal fibres, Kb'll.) virtually represent bundles of two, three, or more
tubular dark-bordered fibres, into which they are speedily converted ; the formation
of the medullary sheath proceeding outwards along the branches.
Dr. Beale has studied the formation of cells and fibres both in embryo and adult
animals, and the following are the principal results of his observations. In both,
cells are formed from nuclei imbedded in granular matter; the new-formed cells
are connected one to another, and two cells thus connected withdraw from each
other, whilst the connecting isthmus lengthens out and becomes a fibre. The fibres
accordingly do not sprout out from a previously insulated simple cell, but are spun
out of the substance of the cell, or nucleus, with which they are connected from the
beginning. Ganglion-cells also increase in number by division into two or more,
and in this case the multiplied fibres belonging to the new cells form a bundle cor-
responding to the nervous stem or peduncle of the original cell. A ganglion-cell may
also arise from (apparently) a nucleus placed in the course of a fibre, viz., a little
oblong granular mass (of germinal matter, Beale) connected at each end with a fibre.
This body first clears up at its circumference, then deviates from the straight line, so
that the two portions of the fibre originally prolonged from its extremities, come to
be connected with it at one side, and finally, by further change in its figure, at one
end of it, as two fibres, whilst their continuations in the bundle from which they have
been, as it were, looped out, run in opposite directions. The two fibres at first proceed
straight from the cell, but afterwards one becomes twisted round the other, and the
coils increase with the age of the cell, but the cell-body dwindles as it grows older.
A nerve-fibre in a fasciculus may also be formed from two nuclei connected at their
ends which withdraw from each other, the connecting thread then lengthening out
into a fibre. For further details, Dr. Beale's original memoir may be consulted.*
To the foregoing may be added the chief conclusions arrived at by von Hensen
from recent observations on the growing nerves in the tadpole's tail. According
to his account, fine nervous branches are seen running out, on the tail fin, into
almost imperceptibly fine filaments. The nerves are at first pale, smooth, without
nuclei, and represent the naked axis-cylinders, though much finer. Then nuclei appear
upon them, but these belong to very long-drawn fusiform cells which now really
inclose these axis-cylinders, and form the primitive sheath of the nerve-fibres ; but
this ensheathment stops before reaching the finest branches, i. e., until they grow
larger. Afterwards the medulla appears. According to von Hensen, nerves do not
grow from cells such as cells of a nervous centre outwards in the direction of their
branches. He thinks the mode is thus. Two nerve-cells are connected by a fibre,
or what may be the rudiment of many fibres ; of the cells, the one is central, the
other eventually becomes a peripheral terminal organ ; (as already stated, he
believes the cutaneous nerve-fibres to be connected with epithelium cells) ; the
latter, in the progress of growth and development, is withdrawn from the former,
and the nerve thus lengthened. Moreover, both cells may divide, and the
nerve or fibre splits in correspondence, so that a nerve comes to be connected
with several central and several peripheral cells. The peripheral cell or cells
may divide more extensively than the central, but as corresponding divisions
take place in the nerve-fibres, every peripheral cell or terminal organ maintains
its connection with the nervous centre. Yon Hensen remarks that the foun-
dation of the nervous centres and of the nerves of special sense, as well a3
those of the skin, is laid in the corneous layer of the blastoderm, from which
both of the central and peripheral cells are derived originally. It will be seen that
* Phil. Trans. 1863.
BLOOD-VESSELS. clxv
the principle of formation of nerve-fibres advanced by von Hensen is substantially the
same as that previously published by Dr. Beale.
Re-union and regeneration of nerves. The divided ends of a nerve that has been
cut across readily reunite, and in process of time true nerve-fibres are formed in the
cicatrix, and restore the continuity of the nervous structure. The conducting pro-
perty of the nerve, as regards both motion and sensation, is eventually re-established
through the re-united part. But, immediately after the section, a process of degene-
ration begins in the peripheral or severed portion of the nerve. The medulla of the
white fibres degenerates into a granular mass consisting, apparently, of fatty mole-
cules, and is then totally removed, while the axial fibre, with the primitive sheath
and nuclei, remains ; but, according to some authorities, the latter also suffer more or
less. After reunion takes place, and usually not till then, the medulla is gradually
restored, the restoration proceeding from the point of reunion outwards along the
nerve, which is then restored to its primitive integrity both in structure and function.
From experiments of Philipeaux and Vulpian, it would seem that in very young
animals restoration of the severed portion may take place without previous reunion.
The degeneration above referred to does not affect the part of the nerve remaining
in connection with the nervous centre, which seems to exert an influence in maintain-
ing the nutrition of the nerve. The ganglia, as well as the brain and spinal cord,
have been shown by Dr. Waller to be centres of this influence. He found that, in the
central and undegenerated portion of a divided spinal nerve, while the fibres belong-
ing to the anterior root owe their integrity to their connection with the spinal cord,
those of the posterior root are similarly dependent on the ganglion ; and that, if the
posterior root be cut between the ganglion and the spinal cord, not only will the fibres
which belong to it in the trunk of the nerve beyond the ganglion remain unchanged,
but also those above the ganglion, in the portion of the root left in connection with
it ; whereas the segment of the same root which remains connected with the cord but
severed from the ganglion degenerates. Section of the sympathetic nerve in the neck
is followed by degeneration of the cephalic segment as high as the superior cervical
ganglion, but no farther.
BLOOD-VESSELS.
The blood, from which the solid textures immediately derive material for
their nourishment, is conveyed through the body by branched tubes named
blood-vessels. It is driven along these channels by the action of the heart,
which is a hollow muscular organ placed in the centre of the sanguiferous
system. One set of vessels, named arteries, conduct the blood out from the
heart and distribute it to the different regions of the body, whilst other
vessels named veins bring it back to the heart again. From the extreme
branches of the arteries the blood gets into the commencing branches of the
veins or revehent vessels, by passing through a set of very fine tubes which
connect the two, and which, though not abruptly or very definitely marked
off from either, are generally spoken of as an intermediate set of vessels, and
by reason of their sinallness are called the capillary (i.e., hair- like) vessels, or,
simply, the capillaries.
The conical hollow muscular heart is divided internally into four cavities,
two placed at its base, and named auricles, and two occupying the body and
apex, named ventricles. The auricles are destined to receive the returning
blood from the great veins, which accordingly open into them, and to pass it
on into the ventricles ; whilst it is the office of the latter to propel the blood
through, the body. The ventricles have therefore much thicker and stronger
sides than the auricles, and the great arterial trunks lead off from them.
Each auricle opens into the ventricle of the same side, but the right auricle
and ventricle are entirely shut off from those of the left side by an imper-
vious partition placed lengthwise in the heart.
The blood is sent out by the left ventricle into the main artery of the
body, named the aorta, and passes through the numerous subordinate
clxvi BLOOD-VESSELS.
arteries, which are branches of that great trunk, to the different parts of the
system ; then, traversing the capillaries, it enters the veins, and is returned
by two great venous trunks, named the superior and inferior venae cavse, to
the right auricle. In passing from the arteries to the veins the blood
changes in colour from red to dark, and is otherwise altered in quality in
this condition it is unfit to be again immediately circulated through the
body. On returning, therefore, to the right side of the heart, the blood,
now dark and venous, must re-acquire the florid hue and other though less
obvious qualities of arterial blood before it is permitted to resume its course.
For this purpose, being discharged by the right auricle into the right ven-
tricle, it is driven, by the contraction of that ventricle, along the pulmonary
artery and its branches to the lungs, where, passing through the capillary
vessels of these organs, it is exposed to the influence of the air, and under-
goes the requisite change ; and, having now become florid again, it enters the
commencing branches of the pulmonary veins, which, ending by four trunks
in the left auricle, convey it into that cavity, whence it is immediately dis-
charged into the left ventricle to be sent again along the aorta and through
the system as before.
The blood may thus be considered as setting out from any given point of
the sanguiferous system and returning to the same place again after per-
forming a circuit, and this motion is what is properly termed the circulation
of the blood. Its course from the left ventricle along the aorta, throughout
the body, and back by the venae cavse to the right ventricle, is named the
greater or systemic circulation, and its passage through the lungs by the
pulmonary artery and pulmonary veins from the right to the left side of the
heart, is termed the lesser or pulmonary circulation ; but the blood must go
through both the greater and the lesser circulations in order to perform a
complete circuit, or to return to the point from which it started. As the
vessels employed in the circulation through the lungs have been named pul-
monary, so the aorta which conveys the blood to the system at large is
named the systemic artery, and the venae cavse the systemic veins ; whilst
the two sets of capillaries interposed between the arteries and veins, the one
in the lungs, the other in the body generally, are respectively termed the
pulmonary and the systemic capillaries.
The blood flows in the arteries from trunk to branches, and from larger
to smaller but more numerous tubes ; it is the reverse in the veins,
except in the case of the vena portce, a vein which carries blood into the
liver. This advehent vein, though constituted like other veins in the first
part of its course, divides on entering the liver into numerous branches, after
the manner of an artery, sending its blood through these branches and
through the capillary vessels of the liver into the efferent hepatic veins to be
by them conducted into the inferior vena cava and the heart.
The different parts of the sanguiferous system above enumerated may be
contemplated in another point of view, namely, according to the kind of
blood which they contain or convey. Thus the left cavities of the heart,
the pulmonary veins, and the aorta or systemic artery, contain red or
florid blood fit to circulate through the body ; on the other hand, the right
cavities of the heart with the venae cavae, or systemic veins, and pulmo-
nary artery, contain dark blood requiring to be transmitted through the
lungs for renovation. The former or red-blooded division of the sangui-
ferous system, commencing by the capillaries of the lungs, ends in the
capillaries of the body at large ; the latter or dark- blooded part commences
in the systemic capillaries and terminates in those of the lungs. The heart
ARTERIES. clxvii
occupies an intermediate position between the origin and termination of
each, and the capillaries connect the (lark and the red sets of vessels together
at their extremities, and serve as the channels through which the blood
passes from the one part of the sanguiferous system to the other, and in
which it undergoes its alternate changes of colour, since it becomes dark as
it traverses the systemic capillaries and red again in passing through those
of the lungs.
ARTERIES.
These vessels were so named from the notion that they naturally contain
air. This error, which had long prevailed in the schools of medicine, was
refuted by Galen, who showed that the vessels called arteries, though for
the most part found empty after death, really contain blood in the living
body.
Mode of Distribution. The arteries usually occupy protected situations ;
thus, after coming out of the great visceral cavities of the body, they run
along the limbs on the aspect of flexion, and not upon that of extension
where they would be more exposed to accidental injury.
As they proceed in their course the arteries divide into branches, and the
division may take place in different modes. An artery may at once resolve
itself into two or more branches, no one of which greatly exceeds the rest
in magnitude, or it may give off several branches in succession and still
maintain its character as a trunk. The branches come off at different
angles, most commonly so as to form an acute angle with the further part
of the trunk, but sometimes a right or an obtuse angle, of which there are
examples in the origin of the intercostal arteries. The degree of deviation
of a branch from the direction of the trunk was supposed to affect the force
of the stream of blood, but Weber maintains that it can produce little or
no effect in a system of elastic tubes maintained, like the arteries, in a state
of distension.
An artery, after a branch has gone off from it, is smaller than before, but
usually continues uniform in diameter or cylindrical until the next secession ;
thus it was found by Mr. Hunter that the long carotid artery of the camel
does not diminish in calibre throughout its length. A branch of an artery
is less than the trunk from which it springs, but the combined area or
collective capacity of all the branches into which an artery divides, is
greater than the calibre of the parent vessel immediately above the point of
division. The increase in the joint capacity of the branches over that of
the trunk is not in the same proportion in every instance of division, and
there is at least one case known in which there is no enlargement, namely,
the division of the aorta into the common iliac and sacral arteries ; still,
notwithstanding this and other possible exceptions, it must be admitted as
a general rule that an enlargement of area takes place. From this it is
plain that, as the area of the arterial system increases as its vessels divide,
the capacity of the smallest vessels aud capillaries will be greatest ; and, as
the same rule applies to the \eins, it follows that the arterial aud venous
systems may be represented, as regards capacity, by two cones whose apices
(truncated it is true) are at the heart, and whose bases aie united in the
capillary system. The effect of this must be to make the blood move more
slowly as it advances along the arteries to the capillaries, like the current of
a river when it flows in a wider and deeper channel, and to accelerate its
speed as it returns from the capillaries to the venous trunks.
When arteries unite they are said to anastomose or inosculate. Anasto-
m 2
clxviii BLOOD-VESSELS.
moses may occur in tolerably large arteries, as those of the brain, the hand
and foot, and the mesentery, but they are much more frequent in the
smaller vessels. Such inosculations admit of a free communication between
the currents of blood, and must tend to promote equability of distribution
and of pressure and to obviate the effects of local interruption.
Arteries commonly pursue a tolerably straight course, but in some parts
they are tortuous. Examples of this in the human body are afforded by
the arteries of the lips and of the uterus, but more striking instances may
be seen in some of the lower animals, as in the well-known case of the long
and tortuous spermatic arteries of the ram and the bull. In very move-
able parts like the lips, this tortuosity will allow the vessel to follow their
motions without undue stretching ; but in other cases its purpose is not
clear. The physical effect of such a condition of the vessel on the blood
flowing along it must be to reduce the velocity, by increasing the extent of
surface over which the blood moves, and consequently the amount of im-
pediment from friction ; still it does not satisfactorily appear why such an
end should be provided for in the several cases in which arteries are known
to follow a tortuous course. The same remark applies to the peculiar
arrangement of vessels named a "rete mirabile," where an artery suddenly
divides into small anastomosing branches, which in many cases unite again
to reconstruct and continue the trunk. Of such retia mirabilia there are
many examples in the lower animals, but, as already remarked, the pur-
pose which they serve is not apparent. The best known instance is that
named the rtte mirabile of Galen, which is formed by the intracranial
part of the internal carotid artery of the sheep and several other quad-
rupeds.
Physical Properties. Arteries possess considerable strength and a very
high degree of elasticity, being extensible and retractile both in their
length and their width. When cut across, they present, although empty, an
open orifice ; the veins, on the other hand, collapse, unless when prevented
by connection with surrounding rigid parts.
Structure. In most parts of the body the arteries are inclosed in a
sheath formed of connective tissue, and their outer coat is connected to the
sheath by filaments of the same tissue, but so loosely that when the vessel
is cut across its ends readily shrink some way within the sheath. The
sheath may inclose other parts along with the artery, as in the case of that
enveloping the carotid artery, which also includes the internal jugular vein
and pneumo-gastric nerve. Some arteries want sheaths, as those for ex-
ample which are situated within the cavity of the cranium.
Independently of this sheath, arteries (except those of minute size whose
structure will be afterwards described with that of the capillaries) have
been usually described as formed of three coats, named, from their rela-
tive position, internal, middle, and external ; and as this nomenclature is
generally followed in medical and surgical works, and also correctly applies
to the structure of arteries so far as it is discernible by the naked eye, it
seems best to adhere to it as the basis of our description ; although it will
be seen, as we proceed, that some of these coats are found by microscopic
examination really to consist of two or more strata differing from each
other in texture, and therefore reckoned as so many distinct coats by some
authorities.
Internal coat. This may be raised from the inner surface of the arte-
ries as a fine transparent colourless membrane, elastic but very easily
broken, especially in the circular or transverse direction, so that it cannot
STRUCTURE OF ARTERIES.
clxix
Fig- XCI.
be stripped off in large pieces. It is very commonly corrugated with very
fine and close longitudinal wrinkles, caused most probably by a contracted
state of the artery after death. Such is the appearance presented by the
internal coat to the naked eye, but by the aid of the microscope it Ls found
to consist of two different structures, namely: 1. An epithelium, forming
the innermost part or lining. This is a simple layer of thin elliptical or
irregularly polygonal scales, which are often elongated into a lanceolate
shape. These epithelial elements have round or oval nuclei, which, how-
ever, may disappear ; indeed, the whole structure sometimes becomes indis-
tinct, especially in the larger arteries. 2. Elastic layers. These form the
chief substance of the inner coat. The elastic tissue appears for the most
part in form of the "perforated" or " fenestrated " membrane of Henle.
This consists of a thin and brittle transparent film, and may exist in one
or several layers ; and in that case it may be stripped off in small shreds,
which have a remarkable tendency to curl in at their upper and lower
borders, and roll themselves up as represented in the figure (fig. XCI.).
The films of membrane are marked by
very fine pale streaks, following prin-
cipally a longitudinal direction, and
joining each other obliquely in a sort
of network. Henle considers these
lines to be reticulating fibres formed
upon the membranous layer. This mem-
brane is further remarkable by being
perforated with numerous round, oval,
or irregularly shaped apertures of dif-
ferent sizes. In some parts of the arte-
ries the perforated membrane is very
thin, and therefore difficult to strip off ;
in other situations it is of considerable
thickness, consisting of several layers ;
but it often happens that the deeper
layers of the elastic structure, i. ,, those
farther from the inner surface, lose their
membranous character, and pass into a
mere network of longitudinal anasto-
mosing fibres of elastic tissue. These
longitudinal reticulating fibres are, however, sometimes spoken of as consti-
tuting a distinct coat.
The inner coat may thus be said to be formed of epithelium and elastic
layers ; the latter consisting of elastic tissue under two principal forms,
namely, the fenestrated membrane and the longitudinal elastic networks :
and these two forms may coexist in equal amount, or one may predominate,
the other diminishing or even disappearing altogether.
It is further to be observed, that in the inner coat of the aorta and the larger
arteries, in addition to the elements described, lamellae are found of a clear, homoge-
neous, often striated or sometimes even fibrillated substance, mostly of the nature of
connective tissue, and pervaded by longitudinal elastic networks of varying fine-
ness. Immediately beneath the epithelium these transparent layers, the striated
layers (Kolliker), may contain imbedded nuclei, which have been found by
Langhans to belong to branched or irregularly stellate cells ; or they may be more
uniform and destitute of nuclei, in which case they more resemble elastic mem-
branes.
TEIVT, MAGNIFIED 200 DIAMETERS (from
Henle).
a , b, c, perforations.
clxx
BLOOD-VESSELS.
Middle coat. This consists of plain muscular tissue, in fine bundles, disposed
circularly round the vessel, and consequently tearing off in a circular direction,
although the individual Bundles do not form complete rings. The consider-
able thickness of the walls of the larger arteries is due chiefly to this coat ;
and in the smaller ones, it is said to be thicker in comparison with the calibre
of the vessel. In the largest vessels it is made up of many layers ; and
shreds of elastic membrane, homogeneous,
finely reticular, or quite similar to the
fenestrated membrane of the inner coat,
are often found between the layers. The
middle coat is of a tawny or reddish-yellow
colour, not unlike that of the elastic tissue,
but, when quite fresh, it has a softer and
more translucent aspect. Its more internal
part is often described as redder thau the
rest, but the deeper tint is probably duo
to ctaiuing by the blood after death. This
coat is highly elastic, and was at one time
regarded by many, especially among the
French anatomists, as being identical in
nature with the yellow elastic tissue : but
it consists in reality of two constituents ;
namely, 1st, muscular fibre-cells, seldom
more than from -^^ to -^Q of an inch
long, collected in bundles, as already
stated ; 2ndly, fine elastic fibres mixed
with the muscular bundles and traversing
the muscular lasers in the form of elastic
net- works, which, in the larger arteries, pass
into the elastic laminae already mentioned,
The elastic fibres are accompanied by white
fibres of areolar tissue in small quan-
tity, the proportion of which increases with the size of the artery. It
is important further to note that the muscular tissue of the middle coat
is more pure in the smaller arteries, and that the admixture of other
tissues increases in the larger sized vessels ; in these, moreover, the
muscular cells are smaller. Accordingly, the vital contractility of the
arteries, which depends on their middle coat, is very little marked in
those of large size, but becomes much more conspicuous in the smaller
branches.
External coat. This consists of two layers of different texture, viz.
1st, an internal stratum of genuine elastic tissue, most obvious in arte-
ries of medium calibre, and becoming thinner, and at length disappear-
ing in those of small size ; 2ndly, an outer layer, consisting of fine,
and closely felted bundles of white connective tissue, mixed with elastic
fibres. The bundles and fibres in large and middle-sized arteries chiefly
run diagonally or obliquely round the vessel, and their interlacement
becomes much more open and lax towards the surface of the artery, where
they connect the vessel with its sheath or with other surrounding parts,
This white fibrous layer is usually of great proportionate thickness in the
smaller arteries.
Some arteries have much thinner coats than the rest, in proportion to
their calibre. This is strikingly the case with those contained within the
Fig. XCII. MUSCULAR FIBRE CELLS
FROM HUMAN ARTERIES. MAGNI-
FIED 350 DIAMETERS.
1. From the popliteal artery; a,
natural ; 6, treated with acetic acid.
2. From a small branch of the poste-
rior tibial (from Kolliker).
ARTERIES, CONTRACTILITY OF.
cavity of the cranium, and in the vertebral canal ; the difference depends on
the external and middle coats, which in the vessels referred to are thinner
than elsewhere.
The coats of arteries receive small vessels, both arterial and venous, named
vasa vasorum, which serve for their nutrition, The little nutrient arteries do
not pass immediately from the cavity of the main vessel into its coats, but
are derived from branches which arise from the artery (or sometimes from a
neighbouring artery), at some distance from the point where they are ulti-
mately distributed, and divide into smaller branches within the sheath, and
upon the surface of the vessel, before entering its coats. They form a net-
work in the tissue of the external coat, from which a few penetrate into the
middle coat, and follow the circular course of its fibres ; none have been
discovered in the internal coat, unless the observations of Jasche and Arnold
are to be trusted, who affirm that they have seen vessels in that situation.
Minute venules return the bJood from these nutrient arteries, which, however,
they do not closely accompany, and discharge it into the vein or pair of veins
which usually run alongside the artery.
Arteries are generally accompanied by larger or smaller nerves ; and when,
in the operation of tying an artery, these happen to be included along with
it in the ligature, great pain is experienced, but the vessel itself, when in a
healthy condition, is insensible. Nerves are, nevertheless, distributed to the
coats of arteries, probably for governing their contractile movements. The
nerves come chiefly from the sympathetic, but also from the cerebro-spiual
system. They form plexuses round the larger arteries, and run along the
smaller branches in form of fine bundles of fibres, which here and there twist
round the vessel, and single nerve fibres have been seen closely accompanying
minute arteries. The fine branches destined for the artery penetrate to the
middle coat, in which they are chiefly distributed. They lay aside their
medullary sheath and form a plexus of pale fibres, the finest of which are
without nuclei.
Vital properties. Contractility. Besides the merely mechanical property of elas-
ticity, arteries are endowed in a greater or less degree with vital contractility, by
means of which they can narrow their calibre. This vital contractility, which has
doubtless its seat in the plain muscular tissue of the middle coat, does not cause rapid
contractions following in rhythmic succession like those of the heart ; its operation
is, on the contrary, slow, and the contraction produced is of long endurance. Its
effect, or its tendency, is to contract the area of the arterial tube, and to offer a cer-
tain amount of resistance to the distending force of the blood ; and as the contracting
vessel will shrink the more, the less the amount of fluid contained in it, the vital con-
tractility would thus seem to adjust the capacity of the arterial system to the quan-
tity and force of the blood passing through it, bracing up the vessels, as it were, and
maintaining them in a constant state of tension. In producing this effect, it co-ope-
rates with the elasticity of the arterial tubes, but it can be shown that after that
property has reached its limit of operation the vital contraction can go further in
narrowing the artery. The vital or muscular contractility of the arteries, then, coun-
teracts the distending force of the heart and seems to be in constant operation. Hence
it is often named "tonicity," and so far justly ; but at the same time, like the con-
tractility of other muscular structures, it can, by the application of various stimuli,
be artificially excited to more vivid action than is displayed in this natural tonic or
balanced state ; and, on the other hand, it sometimes relaxes more than the habitual
degree, and then the vessels yielding to the distending force of the heart become
unusually dilated. Such a remission in their contractile force (taking place rather
suddenly) is probably the cau*e of the turgescence of the small vessels of the skin
which occurs in blushing ; and the arteries of erectile organs are probably affected in
the same manner, so as to permit an augmented flow of blood into the veins or
venous cavities when erection begins.
clxxii BLOOD-VESSELS.
The vital contractility of small-sized arteries is easily demonstrated in the trans-
parent parts of cold-blooded animals. If the point of a needle be two or three times
drawn quickly across one of the little arteries (not capillaries) in the web of a frog's
foot placed under the microscope, the vessel will be seen slowly to contract, and the
stream of blood passing through it becomes smaller and smaller, and, by a repetition
of the process, may be made almost entirely to disappear. After persisting in this
contracted state for some minutes, the vessel will gradually dilate again to its original
size. The same effect may be produced by the application of ice-cold water, and also
by electricity, especially the interrupted electric current. Moreover, if one of the
small arteries in the mesentery of a frog or of a small warm-blooded animal, such as a
mouse (Poiseuille), be compressed so as to take off the distending force of the blood
from the part beyond the point where the pressure is applied, that part will diminish
in calibre, at first no doubt from its elasticity, and therefore suddenly, but afterwards
slowly. This gradual shrinking of an emptying artery after its elasticity has ceased
to operate, may be shown also by cutting out the frog's heart or dividing the main
trunks of the vessels ; it is obviously due to vital contraction. The contractility of the
smaller arteries, as well as its subjection to the influence of the nervous system, is
beautifully shown in the experiment of cutting and afterwards stimulating the cervical
sympathetic nerve in a cat or rabbit. Immediately after the section, the vessels of
the ear become distended with blood from failure of their tonic contraction ; but, on
applying the galvanic stimulus to the upper portion of the nerve, they immediately
shrink again, and on interrupting the stimulation they relax as before. The tonic
contraction of these vessels appears to be maintained by the spinal cord operating
through the branches of the cervical part of the sympathetic nerve ; it has been found,
moreover, that direct stimulation of the spinal cord causes contraction of other arteries,
probably through branches of spinal nerves.
The contractility of the middle-sized and larger arteries is not so conspicuous, and
many excellent observers have failed to elicit any satisfactory manifestation of such
property on the application of stimuli to these vessels. Others, however, have observed
a sufficiently decided, though by no means a striking degree of contraction slowly to
follow mechanical irritation or electric stimulation of these arteries in recently-killed
animals. To render this effect more evident, my former colleague, Dr. C. J. B. Wil-
liams, adopted a method of experimenting which he had successfully employed to test
the irritability of the bronchial tubes. He tied a bent glass tube into the cut end of
an artery, and filled the vessel, as well as the bend of the tube with water ; the appli-
cation of galvanism caused a narrowing of the artery, the reality of which was made
manifest by a rise of the fluid in the tube. Contraction is said also to follow the
application of chemical stimulants, but, as these may directly corrugate the tissue by
their chemical action, the evidence they afford is less satisfactory. Cold causes con-
traction of the larger arteries, according to the testimony of various inquirers; and,
as in the smaller arteries, a gradual shrinking in calibre ensues in these vessels, when
the distending pressure of the blood is taken off, by the extinction or impairment of
the force of the heart on the approach of death. From the experiments of Dr. Parry,
it would appear that the contraction thus ensuing proceeds considerably beyond what
would be produced by elasticity alone, and that it relaxes after death, when vitality is
completely extinct, so that the artery widens again to a certain point, at which it is
finally maintained by its elasticity.
VEINS.
Mode of distribution. The veins are ramified throughout the boily, like
the arteries, but there are some differences in their proportionate number
and size, as well as in their arrangement, which require to be noticed.
In most regions and organs of the body the veins are more numerous
and also larger than the arteries, so that the venous system is altogether
more capacious than the arterial, but the proportionate capacity of the two
cannot be assigned with exactness. The pulmonary veins form an exception
to this rule, for they do not exceed in capacity the pulmonary arteries.
The veins are arranged in a superficial and a deep set, the former running
STRUCTURE OF VEINS. clxxiii
immediately beneath the skin, and thence named subcutaneous, the latter
commonly accompanying the arteries, and named vence comites vel satellites
arteriarum. The large arteries have usually one accompanying vein, and
the medium-sized and smaller arteries two ; but there are exceptions to this
rule ; thus, the veins within the skull and spinal canal, the hepatic veins,
and the most considerable of those belonging to the bones, run apart from
the arteries.
The communications or anastomoses between veins of considerable size,
are more frequent than those of arteries of equal magnitude.
Structure. The veins have much thinner coats than the arteries, and
collapse when cut across or emptied ; whereas a cut artery presents a patent
orifice. Notwithstanding their comparative thinness, however, the veins
possess considerable strength, more even, according to some authorities, than
arteries of the same calibre. The number of their coats has been differently
reckoned, and the tissues composing them differently described by different
writers, and this discrepancy of statement is perhaps partly due to the
circumstance that all veins are not perfectly alike in structure. In most
veins of tolerable size, three coats may be distinguished, which, as in the
arteries, have been named external, middle, and internal
The internal coat is less brittle than that of the arteries, and therefore
admits of being more readily peeled off without tearing ; but, in other
respects, the two are much alike. It consists of an epithelium, a striated
lamella containing nuclei, and the usual elastic layers ; these occur as dense
lamelliform networks of longitudinal elastic fibres, and but seldom as fene-
strated membranes.
The middle coat is much thinner than that of the arteries, and its muscu-
lar tissue has a much larger admixture of white connective tissue. Its
fibres are both longitudinal and circular, the one set alternating with the
other in layers. The former are well developed elastic fibres, longitudinally
reticulating ; the circular layers consist of bundles of muscular fibre-cells
and white connective tissue, mixed with a smaller proportion of fine
elastic fibres. In medium-sized veins the middle coat contains several suc-
cessions of the circular and longitudinal layers, but the latter are all more
or less connected together by elastic fibres passing through the intervening
circular layers. In the larger veins the middle coat is less developed,
especially as regards its muscular fibres, but in such cases the deficiency may
be supplied by muscularity of the outer coat. Kolliker states that the
middle coat is wanting altogether in most of the hepatic part of the vena
cava, and in the great hepatic veins ; and even where its thickness is con-
siderable, it is less regularly or not at all disposed in layers, and its muscular
fibres are more scanty. The muscularity of the middle coat is best marked
in the splenic and portal veins ; it is apparently wanting in certain parts of
the abdominal cava and in the subclavian veins.
The external coat is usually thicker than the middle coat ; it consists of
connective tissue and longitudinal elastic fibres. In certain large veins, as
pointed out by Remak, this coat contains a considerable amount of plain or
non-striated muscular tissue. The muscular elements are well marked in
the whole extent of the abdominal cava, in which they form a longitudinal
network, occupying the inner part of the external coat ; and they may be
traced into the renal, azygos, and external iliac veins. The muscular tissue
of the external coat is also well developed in the trunks of the hepatic veins
and in that of the vena portse, whence it extends into the splenic and
superior mesenteric.
clxxiv
BLOOD-VESSELS.
Other veins present peculiarities of structure, especially in respect of muscularity.
1. The striated muscular fibres of the auricles of the heart are prolonged for some way
on the adjoining part of the venae cavae and pulmonary veins. 2. The plain muscular
tissue is largely developed in the veins of the gravid uterus, and is described as being
present in all three coats. 3. On the other hand, muscular tissue is wanting in the
following veins, viz., a, those of the maternal part of the placenta ; b, most of the veins
of the brain and pia mater ; c, the veins of the retina ; d, the venous sinuses of the
dura mater ; e, the canceUar veins of the bones ; /, the venous spaces of the corpora
cavernosa. In most of these cases the veins consist merely of an epithelium and a
layer or layers of connective tissue more or less developed ; in the corpora cavernosa
the epithelium is applied to the trabecular tissue. It may be added that in the
thickness of their coats the superficial veins surpass the deep, and the veins of the
lower limbs those of the upper.
The coats of the veins are supplied with nutrient vessels, vasa vasorum,
in the same manner as those of the arteries. Nerves have not been demon-
strated in the coats of veins generally, but small branches have been traced
on some of the larger veins.
Vital properties. Veins, when in a healthy condition, appear to be almost devoid
of sensibility. They possess vital contractility, which shows itself in the same manner
as that of the arteries, but is greatly inferior in degree, and much less manifest. The
muscular parts of the great veins, near the auricles of the heart, on being stimulated,
in recently killed quadrupeds, exhibit quick and decided contractions, somewhat
resembling those of the auricles themselves. Mr. Wharton Jones has discovered a
rhythmic pulsation in the veins of the bat's wing, the pulsation occurring from ten to
twelve times in a minute ; and it is worthy of note that the muscular tissue of these
veins appears to be of the plain or unstriped variety.
Valves. Most of the veins are provided with valves, a mechanical con-
trivance beautifully adapted to prevent the reflux of the blood. The valves
are formed of seiniluuar folds of the
lining membrane, strengthened by
included counectivetissue, which pro-
ject obliquely into the vein. Most
commonly two such folds or flaps
are placed opposite each other (fig.
xcm. A) ; the convex border of each,
which, according to Haller, forms a
parabolical curve, is connected with
the side of the vein ; the other edge
is free, and points towards the heart,
or at least in the natural direction
of the current of the blood along the
vessel, and the two flaps obliquely
incline towards each other iu this
direction. Moreover, the wall of
the vein immediately above (or
nearer the heart than) the curved
line of attachment of the valves, is
dilated into a pouch or sinus on each
side (fig. xciii. B a), so that, when
distended with blood or by artificial
Fig. XCIII.
Fig. XCIII. DIAGRAMS SHOWING VALVES
OP VEINS.
A. Part of a vein laid open and spread
out, with two pairs of valves. B. Longitu-
dinal section of a vein, showing the apposi-
tion of the edges of the valves in their closed
state. 0. Portion of a distended vein, ex-
hibiting a swelling in the situation of a pair
of valves.
injection, the vessel bulges out on
each side, and thus gives rise to the appearance of a knot or swelling wherever
a valve is placed (as in fig. c). From the above description, it is plain that
the valves are so directed as to offer no obstacle to the blood in its
CAPILLARY VESSELS. clxxv
onward flow, but that, when from pressure or any other cause it is driven
backwards, the refluent blood, getting between the dilated wall of the
vein and the flaps of the valve, will press them inwards until their edges
meet in the middle of the chumel and close it up.
The valvular folds are usually placed in pairs as above described ; in the veins of
the horse and other large quadrupeds three are often found ranged round the inside of
the vessel ; but this rarely occurs in the human body. On the other hand, the valves
are placed singly in some of the smaller veins, and in large veins single valves are not
unfrequently placed over the openings of smaller entering branches; also in the right
auricular sinus of the heart there is a single crescentic fold at the orifice of the vena
cava inferior, and another more completely covering the opening of the principal
coronary vein.
Many veins are destitute of valves. Those which measure less than a line in
diameter rarely, if ever, have them. In man, valves are wanting in the trunks of the
superior and inferior venae cavae, in the trunk and branches of the portal vein, in the
hepatic, renal, and uterine veins ; also in the spermatic veins of the female. In the
male, these last mentioned veins have valves in their course, and in each sex a little
valve is occasionally found in the renal vein, placed over the entrance of the spermatic.
The pulmonary veins, those within the cranium and vertebral canal, and those of the
cancellated texture of bone, as well as the trunk and branches of the umbilical vein,
are without valves. Valves are not generally found, and when present are few in
number, in the azygos and intercostal veins. On the other hand, they are numerous
in the veins of the limbs (and especially of the lower limbs), which are much exposed
to pressure in the muscular movements or from other causes, and have often to sup-
port the blood against the direction of gravity. No valves are met with in the veins
of reptiles and fishes, and not many in those of birds.
CAPILLARY VESSELS.
That the blood passes from the arteries into the veins was of course a
necessary part of the doctrine of the circulation, as demonstrated by Harvey;
but the mode in which the passage takes place was not ascertained until
some time after the date of his great discovery. The discovery of the
capillary vessels, and of the course of the blood through them, was destined
to be one of the first fruits of the use of the microscope in anatomy and
physiology, and was reserved for Malpighi (in 1661).
When the web of a frog's foot is viewed through a microscope of mode-
rate power (as in fig. xciv.), the blood is seen passing rapidly along the
small arteries, and thence more slowly through a network of finer
channels, by which it is conducted into the veins. These small vessels,
interposed between the finest branches of the arteries and the commencing
veins, are the capillary vessels. They may be seen also in the lungs or
mesentery of the frog and other batrachians, and in the tail and gills of
their larvae : also in the tail of small fishes ; in the mesentery of mice or
other small quadrupeds ; and generally, in short, in the transparent vas-
cular parts of animals which can readily be brought under the microscope.
These vessels can also be demonstrated by means of fine injections of
coloured material, not only in membranous parts, such as those above-
mentioned, but also in more thick and opaque tissues, which can be rendered
transparent by drying.
The capillary vessels of a part are most commonly arranged in a network,
tho branches of which are of tolerably uniform size, though not all strictly
equal ; and thus they do not divide into smaller branches like the arteries,
or unite into larger ones like the veins ; but the diameter of the tubes, as
well as the shape and size of the reticular meshes which they form, dnTers in
clxxvi
BLOOD-VESSELS.
Fig. XCIV.
Fig. XCIV. CAPILLARY BLOOD-
VESSELS IN THE WEB OP A FROG'S
FOOT, AS SEEN WITH THE MICRO-
SCOPE (after Dr. Allen Thom-
son).
The arrows indicate the course of
the blood.
different textures. Their prevalent size in the human body may, speaking
generally, be stated at froin^ 1 ^ to ^^ of an inch, as measured when
naturally filled with blood. But they are said to be in some parts consider-
ably smaller, and in others larger than this standard : thus, Weber has
measured injected capillaries in the brain, which he found to be not wider
than ^-yo-o" f an inch, and Henle has
observed some still smaller, in both cases
apparently smaller than the natural diameter
of the blood-corpuscles. The capillaries,
however, when deprived of blood, probably
shrink in calibre immediately after death ;
and this consideration, together with the
fact that their distension by artificial in-
jection may exceed or fall short of what
is natural, should make us hesitate on
such evidence to admit the existence of
vessels incapable of receiving the red par-
ticles of the blood. The diameter of the
capillaries of the marrow, or of the medul-
lary membrane, is stated as high as -J-^QQ
of an inch. In other parts, their size
varies between these extremes : it is small
in the lungs, small also in muscle ; larger
in the skin and mucous membranes.
According to Mr. Toynbee, the extreme
branches of the arteries and the com-
mencing veins in certain parts of the synovia! membranes are connected by
loops of vessels, which are dilated at their point of flexure to a greater
size even than the vessels which they immediately connect.
There are differences also in the size or width of the meshes of the
capillary network in different parts, and consequently in the number of
vessels distributed in a given space, and the amount of blood supplied to
the tissue. The network is very close in the lungs and in the choroid coat
of the eye, close also in muscle, in the skin, and in most parts of the
mucous membrane, in glands and secreting structures, and in the grey part
of the brain and spinal cord. On the other hand, it has wide meshes and
comparatively few vessels in the ligaments, tendons, and other allied tex-
tures. In infants and young persons, the tissues are more vascular than in
after-life ; growing parts, too, are more abundantly supplied with vessels
than those which are stationary.
The figure of the capillary network is not the same in all textures. In
many cases the shape of the meshes seems accommodated to the arrange-
ment of the elements of the tissue in which they lie. Thus in muscle, nerve,
and tendon, the meshes are long and comparatively narrow, and run con-
formably with the fibres and fasciculi of these textuies (fig. xcv.). In
other parts the meshes are rounded or polygonal, with no one dimension
greatly predominating (fig. xcvi.). In the smaller-sized papillae of the skin
and mucous membranes, the vessels of the network are often drawn out
into prominent loops.
Structure of the small- sized vessels and capillaries. The capillary vessels
have real coats, and are not mere channels drilled in the tissue which they
pervade, as has sometimes been maintained. In various parts they are
readily separable from the surrounding substance, as in the brain and
STRUCTURE OF CAPILLARIES.
clxxvii
Fig. XCV. INJECTED CAPILLARY VESSELS OP MUSCLE,
SEEX WITH A LOW MAGNIPYIfcG POWER.
Fig. XCVI. NET-WORK OP CAPILLARY VESSELS OP THE
AIR-CELLS OP THE HORSE'S LUNG, MAGNIFIED.
a, a, capillaries proceeding from b, b, terminal branches
of the pulmonary artery (after Frey).
retina, and in such, cases it is easy to display their independent membra-
nous parietes. The
Fig. XCV. Fig. XCVI. number as well as
the structure of the
coats of the capillaries
differs according to
the size of the vessels.
Capillaries of a diame-
ter less than ^ ff
of an inch, were
until lately believed
to have but a single
coat, formed of simple
homogeneous trans-
parent membrane,
with nucleiform cor-
puscles attached to it
or inclosed in its sub-
stance ; but from re-
cent researches (by
Auerbach, Eberth, and
Chrzonszczewsky,) it
has been ascertained
that they are fur-
nished with an epi-
thelium, to which the
nuclei of the capillary
coat really belong. The cells of the epithelium are, as in the larger
vessels, flattened into scales and form but a single layer, in which the
outline of the scales, or their lines of junction one with another, may be
made apparent by nitrate of silver injection ; after which the nuclei may be
brought into view by acetic acid or carmine (fig. xcvii.). The epithelium
scales, which are polygonal in the small arteiies and veins (A, v), gradually
become oblong or spindle-shaped as they pass into the capillaries, and
throughout these vessels the epithelium presents the same characters, only
the flattened cells or scales become longer and narrower in the smaller
capillaries, and fewer in number in the circumference of the tube. In the
brain usually only two cells are to be seen in the cross section of a capillary,
but in the large capillaries of the kidney and bladder the number may rise
to four or five, and in this case the scales are shorter and broader. At the
points of junction of the capillaries the cells are much broader and not
spindle-shaped but radiate, with three or four pointed branches fitting in
between the cells of the three or four adjoining vessels which meet at the
spot (fig. xcvii., c c').
Auerbach describes the capillary wall as formed entirely of flattened
epithelium- cells fitted together at their edges into a continuous and coherent
membrane, without any further supporting structure ; but Chrzonszczewsky
discovered portions of the capillaries in which the epithelium-cells had been
displaced, and where spaces of some extent were left entirely devoid of
nuclei and of the outline markings of the cells ; and in these parts the out-
line of the capillary wall was still entire and continuous, and its substance
quite structureless. He concludes, therefore, that there is a homogeneous
coat, and within this an epithelium, to which the nuclei belong.
clxxviii
BLOOD-VESSELS.
In vessels one or two degrees larger, there is added on the primitive
homogeneous membrane a layer of plain muscular tissue, in form of the usual
Fig. XCVII.
Fig. XCVII. MAGNIFIED VIEW OP CAPILLARY VESSELS FROM THE BLADDER OF THE
CAT.
A, V, an artery and a vein ; ?', transitional vessel between them and cc, the capillaries.
The muscular coat of the larger vessels is left out in the figure to allow the epithelium to
be seen ; at c\ a radiate epithelium-scale with four pointed processes, running out upon
the four adjoining capillaries (after Chrzonszczewsky, Virch. Arch, lbb'6).
oblong contractile fibre-cells, which are directed across the diameter of the
vessel. The elongated nuclei of these cells may be brought into view by
means of acetic acid, as shown in the figure (xcvm). This layer corre-
sponds with the middle or muscular coat of the arteries. In the smallest
vessels in which it appears the muscular cells are few arid apart, and a
single long cell may turn spirally round the tube ; in larger vessels, espe-
cially those of the arterial system, they are of course more densely laid on.
Outside the muscular coat is the areolar or connective tissue coat, con-
taining fibres and connective tissue corpuscles, with longitudinally placed,
nuclei.
In vessels of ^ of an inch in diameter, or even less, the elastic layers of
the inner coat may be discovered (fig. xcvm. , A, 3), in the form generally
of fenestrated membrane, more rarely of longitudinal reticulating elastic
fibres ; while the primitive membrane disappears. The small veins, but
two or three removes from the capillaries, differ from arteries of cor-
responding size, chiefly in the inferior development of their muscular
tissue.
In reference to the structure of capillaries, it is to be further observed
that, in parts which are pervaded by a supporting network of retiform con-
nective tissue, such as the substance of the lymphatic glands, the solitary
STRUCTURE OF CAPILLARIES.
clxxix
and agminated intestinal glands and adjacent mucous membrane, etc., the
small blood-vessels and capillaries commonly receive a coating of connective
tissue corpuscles, which are s-imilar to those of the retiform tissue and con-
nected with the fine trabeculse of the network, by which the vessels are
Fig. XCVIII. A SMALL ARTERY A, WITH A CORRESPONDING VEIN B, TREATED WITH
ACETIC ACID, AND MAGNIFIED 350 DIAMETERS (after Kolliker).
a, external coat with oblong nuclei ; & nuclei of the transverse muscular tissue of the
middle coat (when seen endwise, as at the sides of the vessel, their outline is circular);
7, nuclei of the epithelium- cells ; 8, elastic layers of the inner coat.
thus supported. On the smallest capillaries the corpuscles are but sparingly
distributed, but nevertheless afford a continuous covering to the vessel by
their finely reticulating outrunners. This coating is named by His, who
has most fully described and figured it, the adventitia capillaris.
Vital properties. From the share which the capillaries take in many vital actions
both healthy and diseased, and especially from the part they have been supposed to
play in the process of inflammation, much pains has naturally been bestowed to find
out whether they are endowed with vital contractility. There is still, however, a
difference of opinion on this question ; and, while this property evidently exists in
vessels, however small, provided with a muscular coat, it has not been shown by
equally direct evidence, to belong to the more simply constructed capillaries ; and it
must be confessed, that the proofs commonly adduced of the existence of vital con-
tractility in these vessels, are ambiguous and inconclusive. These proofs are chiefly
the two following : viz., 1st, That stimulants, such as alcohol, oil of turpentine,
pepper, and ice or ice-cold water, applied to the frog's foot or mesentery, cause the
capillary vessels to shrink in diameter, and that this contraction is speedily followed
by their dilatation beyond their natural capacity ; the shrinking of the vessels being
attributed to the direct operation of the stimuli on their contractility, and their sub-
sequent dilatation to the temporary exhaustion of that property, consequent on its
previous undue excitation. 2udly, That, when the vessels are preternaturally dilated
in the way above described; or by the action of ammonia or common salt, they
clxxx BLOOD-VESSELS.
may, after a time, be made to contract to their usual size by the reapplication of
stimuli.
Termination of arteries. The only known termination of arteries is in veins, and
this takes place by means of capillary vessels of some of the forms above described,
unless in the maternal part of the placenta, and in the interior of erectile organs,
in which it has been supposed that small arteries open into wide venous cavities,
without the intervention of capillaries. Additional modes of termination have,
however, been assumed to exist. Thus, it was believed that branches of arteries
ended in exhalant vessels, which, in their turn, terminated by open orifices on the
skin, on the surface of different internal cavities, or in the areolar tissue ; other
arterial branches were supposed to be continued into the ducts of secreting glands,
and it was, moreover, imagined that, besides the red capillaries, there existed finer
vessels, which passed between the arteries and the veins, and from their small-
ness were able to convey only the colourless part of the blood. The existence of
these colourless or ll serous " vessels, as they were called (vasa serosa, vasa non
rubra), was held, by most authorities, to be universal ; by others it was assumed
as necessary, at least, in the colourless textures; but these views have now
been generally abandoned, although they long prevailed almost without question,
and were made the basis of not a few influential doctrines in pathology and
practical medicine. Of course it is not denied, that in growing parts there may be
capillaries in an incomplete state of development, which admit only the plasma of
the blood.
Erectile, or cavernous tissue. By this term is understood a peculiar structure,
forming the principal part of certain organs which are capable of being rendered
turgid, or erected, by distension with blood. It consists of dilated and freely inter-
communicating branches of veins, into which arteries pour their blood, occupying the
areolae of a network formed by fibrous, elastic, and probably contractile bands, named
trabeculae, and inclosed in a distensible fibrous envelope. This peculiar arrangement
of the blood-vessels scarcely deserves to be regarded as constituting a distinct texture,
though reckoned as such by some writers ; it is restricted to a very few parts of the
body, and in these is not altogether uniform in character ; the details of its structure
will, therefore, be considered with the special description of the organs in which it
occurs.
DEVELOPMENT OF BLOOD-VESSELS.
The first vessels which appear are formed within the ovum, in the germinal mem-
brane, and the process subsequently goes on in growing parts of the animal body.
New vessels, also, are formed in the healing of wounds and sores, in the organisation
of effused lymph, in the restoration of lost parts, and in the production of adventi-
tious growths. The following may serve as an outline of the process.
The network of vessels which form the vascular area in the germinal membrane of
the egg at an early stage of incubation (see page li.), consists of arteries and veins
communicating, without capillaries. These vessels are at first solid cylinders of
larger or smaller diameter, made up of formative cells cohering together. By
liquefaction of their substance in the interior, these cylinders become tubes, and
their central cells thus set free are the primitive blood-corpuscles. The uniformly
cellular substance forming the wall of the primitive vessels is then converted
into the different coats. It is probable that a similar mode of formation of arte-
ries and veins goes on within the body of the embryo as its organs and members
are progressively developed; but arteries and veins may also begin as capillaries,
which grow into larger vessels, as will presently be explained.
The small vessels and capillaries originate from nucleated cells similar to those
which at first constitute the different parts of the embryo. The cell-wall, or envelope,
of these cells, shoots out into slender pointed processes, tending in different direc-
tions, so that they acquire an irregularly star-shaped or radiated figure. The pro-
longations from neighbouring cells encounter one another, and join together by their
ends, and the irregularly ramified or reticular cavities thus produced are the channels
of rudimentary capillaries. In growing parts, such as the tail of batrachian larvse,
where new vessels are formed in the vicinity of those already existing, as represented
in the adjoining figure (xcrx.) by Kolliker, not only do the processes of the stellate
cells join those of neighbouring cells, but some of them meet and join with similar
DEVELOPMENT OF BLOOD-VESSELS.
Fig. XCIX.
pointed processes which shoot out from the sides of neighbouring capillary vessels,
and in this manner the new vessels are adopted into the existing system. The
junctions of the cells with each other
or with capillary vessels are, at first, of
great tenuity, and contrast strongly
with the central and wider parts of the
cells; they appear then to be solid,
but they afterwards become pervious
and gradually widen, blood begins to
pass through them, and the capillary
network acquires a tolerably uniform
calibre. The original vascular network
may become closer by the formation of
new vessels in its interstices, and this
is effected by similarly metamorphosed
cells, arising in the areolse and joining
at various points with the surrounding
vessels, and also simply by pointed
offshoots from the existing capillaries
stretching across the intervals and
meeting from opposite sides, so as when
enlarged to form new connecting arches.
From observations made on the foetal
membranes of sheep, Mr. Paget has
found that the mode of formation of
capillaries described by Kolliker in
batrachians, holds good also in mam-
miferous animals.* The simple homo-
geneous coat of the capillaries is thus
formed out of the walls of the coa-
lescing cells; the lining epithelium
must be a subsequent formation. Whilst
the finest capillaries retain this simple
structure, those that are larger acquire
the additional coats already described ;
and arteries and veins, as already stated,
especially the smaller ones, appear to
be formed in the same manner ; indeed,
it would seem not unreasonable to
presume, that the several gradations of
structure seen as permanent conditions Fi S- XCIX - CAPILLARY BLOOD-VESSELS OP
THE TAIL OP A VERY YOUNG FROG LARVA.
MAGNIFIED 350 DIAMETERS (after Kol-
liker).
in vessels of successively larger calibre,
may represent the successive steps by
which a vessel, having originally the
small size and the simple membrane of
a fine capillary, increases in width and
acquires the complex tunics of a vein or
artery. Further observations, however,
are required on this point. Kolliker
states, that many vessels which eventu-
ally attain a medium size, are originally
derived from round cells, which unite in
single or double rows and form the
primitive simple membranous tube of such vessels, by coalescence of their cavities and
walls.
The blood-vessels may be said to increase in size and capacity in proportion to the
demands made on their service. Thus, as the uterus enlarges in pregnancy, its
vessels become enlarged, and when the main artery of a limb is tied, or otherwise
permanently obstructed, collateral branches, originally small and insignificant,
* Supplement to Miiller's Physiology, by Baly and Kirkes, 1848, p. 104.
a, capillaries permeable to blood; &,
granules, attached to the walls of the vessels
and concealing nuclei ; c, hollow prolongation
of a capillary, ending in a point; d t a
branched cell, containing a nucleus and
communicating by three
prolongations of capillaries
e, blood-corpuscles.
granules, and
branches with
already formed
clxxxii LYMPHATIC! SYSTEM.
augment greatly in size, to afford passage to the increased share of blood which they
are required to transmit, and by this admirable adaptation of them to the exigency,
the circulation is restored. In such cases, an increase takes place in length, as well
as in diameter, and accordingly the vessels very commonly become tortuous.
ABSORBENT OR LYMPHATIC SYSTEM.
Under this head we include not only the vessels specially called lymph-
atics, together with the glands belonging to them, but al.-'O those named
lacteal or chyliferous, which form part of the same system, and differ in no
respect from the former, save that they not only carry lymph like the rest,
but are also employed to take up the chyle from the intestines during the
process of digestion and convey it into the blood. An introductory outline
of the absorbent system has already been given at page xlvii.
A system of lymphatic vessels is superadded to the sanguiferous in all
classes of vertebrated animals, but such is not the case in the invertebrata ;
in many of these, the sanguiferous vessels convey a colourless or nearly
colourless blood, but no additional class of vessels is provided for conveying
lymph or chyle, at least none such has hitherto been detected.
Distribution. In man and those animals in which they are present, the
lymphatic vessels are found in neaily all the textures and organs which
receive blood ; the exceptions are few, and with the progress of discovery
may yet possibly disappear.
In the different regions of the body, and in the several internal viscera,
the lymphatics are arranged in a superficial and a deep set. The former
run underneath the skin or under the membranous coats immediately enve-
loping the organs in which they are found ; the latter usually accompany
the deep-seated blood-vessels. The principal lymphatic vessels of a part
exceed the veins in number, but fall short of them in size ; they also anasto-
mose or intercommunicate much more frequently than the veins alongside
of which they run.
Origin. Lymphatics may arise superficially, i. e. immediately underneath
free surfaces, both external and internal, as for example those of the skin
and mucous membranes, or deeply, in the substance of organs.
Plexiform origin. When they arise superficially, the lymphatics most
generally begin in form of networks or plexuses, out of which single vessels
emerge at various points and proceed to enter lymphatic glands or to join
larger lymphatic trunks. Such mode of commencement may be termed the
plexiform. The plexuses for the most part consist of several strata, becoming
finer as they approach the surface, in respect both of the calibre of the
vessels and the closeness of their reticulation. This is shown in figure c.,
which is meant to represent the lymphatic plexuses of the skin. But evtn
the most superficial and finest network is composed of vessels which are
larger than the sanguiferous capillaries.
The short anastomosing branches of these plexuses are often of very un-
equal size, even in the same stratum, some being dilated and almost saccular,
whilst others immediately communicating with these are narrow, so that the
network may assume a varicose character. In some situations the plexuses
have much the appearance of strata of intercommunicating cellular cavities,
and a characteristic example of this appearance is afforded by the intestine
of the turtle after its lymphatics have been injected with mercury ; these
vessels are then seen to emerge from what has all the appearance of a dense
stratum of small rounded cells filled with mercury and lying beneath the
surface of the mucous coat. This appearance, however, may be regarded as
ORIGIN OF LYMPHATICS. clxxxiii
produced by the short distended branches of a very close lymphatic net-
work, and transitions are accordingly met with between this and the more
usual and regular forms.
But whilst the superficial commencement of
lymphatic* is generally plexiform, the rule is p 1 ^ ^
not without exception. The lacteals of the
intestinal villi, for example, although they form
networks in the larger and broader villi, arise
in others by a single vessel beginning with a
blind or closed extremity at the free end of
the villus, whence it sinks down to join the
general plexus of the intestinal membrane.
Lacunar origin. When lymphatics arise
deeply, their origin may be hidden from view,
and the precise mode in which it takes place
unknown. There may be cases in which it is BREAST INJECTED (after
still plexiform ; but another and doubtless more Breschet).
general mode of origin from the interior of ,, . , , , ,
. , ., , . , a, superficial, and o, deeper
organs, long suspected and often upheld on pl exus ; c, a lymphatic vessel,
imperfect evidence, has now been satisfactorily -which proceeded to the axil-
ascertained, which may not inappropriately be I ar 7 glands,
termed lacunar. In this case the lymphatic
vessels proceed from irregular or shapeless spaces in the internal parts
of organs ; the spaces, that is, which intervene between the several struc-
tures of which the organ is composed. Thus, in a gland, they are the
spaces which lie between or surround the blood-vessels, secreting tubes or
saccules, partitioning or inclosing membranes, and the like. Though shape-
less, or at least of no regular form, these anfractuous cavities are limited
and defined by a lining of epithelium, agreeing in character with that of
the lymphatic vessels. It may be presumed that their opposite sides are
in apposition or in near proximity, as in serous membranes, for the lymph
deposited in these recesses is not suffered to accumulate, but is drained off
by the lymphatic vessels which lead out of them.
The lacunar condition of the lymphatic system at its commencement was shown
to exist in the testicle by Ludwig and Tomsa, and has since then been found in the
kidney by Ludwig and Zwarykin, in the thymus gland by Frey, in the spleen by
Tomsa, in the liver (forming canals which inclose the blood-capillaries) by Mac-
Gillivray, and in the salivary glands by Giannuzzi. His has also discovered that
the blood-vessels of the brain and spinal cord are surrounded and inclosed by
lymph-channels perivascular canals which follow their course and eventually
terminate in ordinary lymphatic vessels ; an arrangement that brings to mind an
earlier observation of liusconi, who found that the aorta and mesenteric arteries
of the frog and salamander are inclosed in large lymphatic canals. The spaces
which so extensively separate the frog's skin from the subjacent muscles, were
recognised by the late Professor Johannes Muller as belonging to the lymphatic
svstem, and von Recklinghausen has shown that the subcutaneous lymph-spaces of
the frog's leg communicate with lymphatic vessels which envelope the blood-vessels
of the foot ; also that milk injected into these spaces finds its way into the blood.
The lymphatic system of man and the higher animals, in being thus partly consti-
tuted by lacunee or interstitial receptacles, so far agrees with the sanguiferous system
of crustaceans and insects.
It has been sometimes maintained that the lymphatics of glandular organs com-
municate at their origin with the ducts ; but, although it is no uncommon thing for
matters artificially injected into the ducts of glands, as, for instance, those of the
liver and testicle, to pass into the lymphatics, a careful examination of such cases
n 2
clxxxiv
LYMPHATIC SYSTEM.
Fig. CI.
leads to the conclusion that the injected material does not find its way from the ducts
into the lymphatics by any naturally existing communication, but by accidental
rupture of contiguous branches of the two classes of vessels. It seems probable,
also, that the communications often held to exist between the commencing lympha-
tics, both superficial and deep, and capillary blood-vessels, have no better foundation,
and that the passage of injection, here also relied on as evidence, is to be accounted
for in the same way. A fact mentioned by Kolliker throws light on these alleged
communications with sanguiferous capillaries. In investigating the lymphatics of
the tadpole's tail with the microscope, that observer not unfrequently noticed that
blood-corpuscles got into the lymphatics from the small blood-vessels, and he was
able to recognise in the living animal the communications by which they passed.
At first he looked on these communications as natural, but, after repeated and careful
investigations, he satisfied himself that they were produced accidentally by contusion,
or some other injury inflicted on the parts.
Structure. In structure the lymphatic vessels much resemble the veins,
only their coats are thinner, so thin and transparent indeed that the con-
tained fluid can be readily seen through them. When lymphatics have
passed out from the commencing plexuses and lacunse, they are found to have
three coats. The internal coat is covered with a lining of epithelium, con-
sisting of a single layer of flattened nucleated cells, which in the larger
lymphatics have mostly an oblong figure, but in small or commenciug
vessels are more rounded, with an indented, bluntly serrated, or wavy
border, by which the adjacent cells fit to each other, like the epidermic
cells of grasses and some other plants (fig. ci.). Beneath the epithelium
the inner coat is formed of a layer or
layers of longitudinal elastic fibres. The
middle coat consists of plain muscular
tissue disposed circularly, mixed with
finely reticulating elastic fibres taking the
same direction. The external coat is
composed mainly of white connective
tissue with a sparing intermixture of
longitudinal elastic fibres, and some longi-
tudinal and oblique bundles of plain
muscular tissue. In the thoracic duct
there are striated white layers (as in the
aorta) beneath the epithelium, between
it and the elastic layers of the inner coat ;
and in the middle coat there is a longi-
tudinal layer of white connective tissue
with elastic fibres, immediately within the
muscular layer.
The commencing lymphatics, whether in plexuses or single (as in the
villi), for the most part look like mere channels excavated in the surround-
ing tissue, without independent coats, and they were regarded as such by
various eminent authorities. It has now, however, been ascertained that
they invariably have a lining of epithelium formed of the characteristic
indented scales (fig. ci.), as in other small lymphatics. Tins is made appa-
rent by injection of solution of nitrate of silver, which blackens and brings
into view the serrated lines of juncture of the flattened cells, whilst the
nuclei may be made to appear by means of acetic acid or carmine. But it
is not clearly determined whether there is any other coat outside the epi-
thelium, even in cases where the vessels are separable from the adjoining
tissue. By the same method of preparation an epithelial lining of similarly
Fig. CI. PORTION OF A LYMPHATIC
VESSEL SHOWING ITS PECULIAR EPI-
THELIUM. TREATED WITH NITKATE
OP SILVER. FROM THE INTER-
MUSCULAR LAYER OF THE INTES-
TINE OF THE GUINEA PIG (after
Auerbach). MAGNIFIED 240 DIA-
METERS.
STRUCTURE OF LYMPHATICS. clxxxv
marked character has been shown to exist on the walls of the interstitial
lymph spaces or lacunae of origin.
The lymphatics receive va?a vasorum, which ramify in their outer and
middle coats : nerves distributed to them have not yet been discovered,
although their probable existence has been inferred on physiological grounds.
Vital properties. That the lymphatics are endowed with vital contractility is
shown by the effect of mechanical irritation applied to the thoracic duct, as well as by
the general shrinking and emptying of the lacteal and lymphatic vessels on their
exposure to the contact of cold air, in the bodies of animals opened immediately after
death.
Vahes. The lymphatic and lacteal vessels are furnished with valves
serving the same office as those of the veins, and for the most part con-
structed after the same fashion. They generally consist of two semilunar
folds arranged in the same way as in the valves of veins already described,
but deviations from the usual structure here and there occur. Thus Mr.
Lane has observed some valves in which the planes of the semilunar flaps
were directed not obliquely but transversely across the vessel, an arrange-
ment calculated to impede the flow of fluid in both directions, but not com-
pletely to intercept it in either. In others, described by the same authority,
the two folds, placed transversely as before, coalesced at one end, so as to
represent a transverse septum with an incomplete transverse slit. In a
third variety, he found the valve formed of a circular fold corresponding
with a constriction outside, and probably containing circular contractile
fibres capable of completely closing the tube.
Valves are not present in all lymphatics, but where they exist they
follow one another at much shorter intervals than those of the veins, and
give to the lymphatics, when much distended, a beaded or jointed appear-
ance. Valves are placed at the entrance of the lymphatic trunks into the
great veins of the neck. They are wanting in the reticularly arranged
vessels which compose the plexuses of origin already spoken of ; so that
mercury injected into one of these vessels runs in all dirsctions so as to fill
a greater or less extent of the plexus, and passes along the separate vessels
which issue from it.
The lymphatics of fish and naked amphibia are, generally speaking, desti-
tute of valves, and may therefore be injected from the trunks ; in the turtle
a few valves are seen on the larger lacteals which pass along the mesentery,
but none on those upon the coats of the intestine ; and valves are much
less numerous in the lymphatics and lacteals of birds than in those of
mammiferous animals.
Orifices. It was at one time a prevalent opinion among anatomists that the
lymphatic and lacteal vessels begin on various surfaces by open mouths, through
which extraneous matters are absorbed. This was especially insisted on as regards
the commencing lacteals in the intestinal villi. That opinion has been since given
up ; but quite recently von Recklinghausen has obtained what he considers satis-
factory evidence of openings in the lymphatics on the surface of the peritoneum. He
stretched the tendinous centre of the diaphragm, excised from a rabbit, over a ring of
cork, covered it with a film of milk, and then, watching it with the microscope, saw
the milk-globules at various points drawn down as if in a vortex, and disappearing.
He then found they had passed into the lymphatics of the peritoneal covering of the
diaphragm, by small openings, not more than twice the diameter of a blood-corpuscle,
over which the peritoneal epithelium was similarly perforated. Observations in con-
firmation of these have since been made in the Physiological Institute of Leipsic,
under the direction of Professor Ludwig, by Dr. Dybkowski, who has found epithe-
lial apertures (answering very nearly to those described by von Recklinghausen) on
clsxxvi LYMPHATIC SYSTEM.
the dog's pleura, by which the superficial lymphatics open on the surface of the mem-
brane; he also found that fine particles of colouring matter could, under certain con-
ditions, be made to pass from the cavity of the pleura into the lymphatics, and appa-
rently by the openings in question.*
^Respecting these observations, however, it must be remarked, that the apertures
described do not open upon a surface in contact with extraneous matters, as that of
the skin or a mucous membrane, but into a serous cavity ; and perhaps they may be
explained on the supposition that the peritoneum, pleura, and other serous sacs, are
really large lymph-lacunae, from which lymphatic vessels lead out as emissaries, as in
the case of the subcutaneous lymph-spaces of the frog, and the testicular and other
lymph lacunae constructed on a smaller scale.
Absorbent or lymphatic glands, named also conglobate glands, and by
modern French writers lymphatic ganglions, are small solid bodies placed in
the course of the lymphatics and lacteal*, through which the contents of
these vessels have to pass in their progress towards the thoracic or the
right lymphatic duct. These bodies are collected in numbers along the
course of the great vessels of the neck, also in the thorax and abdomen,
especially in the mesentery and alongside the aorta, vena cava inferior, and
iliac vessels. A few, usually of small size, are found on the external parts
of the head, and considerable groups are situated in the axilla and gioiu.
Some three or four lie on the popliteal vessels, and usually one is placed a
little below the knee, but none farther down. In the arm they are found
as low as the elbow-joint.
Lymphatic vessels may pass through two, three, or even more lymphatic
glands in their course, whilst, ou the other hand, there are lymphatics which
reach the thoracic duct without encountering any gland in their way.
The size of these bodies is very various, some being not much bigger
than a hempseed, and others as large or larger than an almond or a kidney-
bean. In shape, too, they present differences, but most of them are round
or oval.
The lymphatics or lacteals which enter a gland are named inferent or
afferent vessels (vasa infer entia sen afferentia), and those which issue from
it efferent vessels (vasa efferentia). The afferent vessels, on approaching a
gland, divide into many small branches, which enter the gland ; the
efferent vessels commonly leave the gland in form of small branches, and at
a little distance beyond it, or sometimes even before issuing from it, unite
into one or more trunks, usually larger in size but fewer in number than
those of the afferent vessels.
The internal structure of lymphatic glands has been long a subject of
inquiry. Hewson considered that a lymphatic gland essentially consists of
a network of finely divided lymphatic vessels, on and between which capil-
lary blood-vessels are ramified ; the whole being gathered up and compacted
into a comparatively dense mass by connective tissue, which at the surface
of the gland forms for it an inclosing capsule. The afferent and efferent
vessels are, according to Hewson, continuous with each other within the
gland, and the cellular cavities described as intervening between them and
serving as the medium of their communication, were held by him to be
nothing more than partial dilatations of some branches of the common con-
necting plexus.
Hewson's view of the constitution of the lymphatic glands was, till
* Bericbte der K. Sachs. Gesellsch. der Wissensch. July, 1866, p. 191. In the
same publication, p. 247, is an account, by F. Schweigger-Seidel and J. Dogiel, of open
communications between the frog's peritoneum and the great lymph-sac (cisterna magna)
behind it ; also founded on observations made in the Physiological Institute of Leipsic.
LYMPHATIC GLAXDS. clxxxvii
lately, accepted by most anatomists ; but recent researches have shown
that the structure of these bodies is more complex. The following account
is founded on the descriptions of His and Kolliker.
A lymphatic gland is covered externally with a coat composed of con-
nective tissue, mixed in certain animals, with muscular fibre-cells. This
coat or capsule is complete, except at the part where it gives passage to the
efferent lymphatics and the larger blood-vessels ; and this part of the
gland, which often presents a depression or fissure, may be named the
hilus (fig. en. a). The proper sub-
stance of the gland consists of two
parts, the cortical, and within this
the medullary. The cortical part
occupies all the superficial part of
the gland, except the hilus, and in
the larger glands may attain a thick-
ness of from two to three lines.
The medullary portion occupies the
centre, and extends to the surface
at the hilus. It is best marked in
the inwardly seated glands, such as
the lumbar and meseuteric, whilst
in the subcutaneous glands it is more Fi ?; CII. -SECTION OF A MESENTERIC
f GLAND FROM THE Ox, SLIGHTLY MAQNI-
or less encroached upon by a core of FIED
connective tissue, hilus-stroma (His), , .,
' V /' a , hilus ; b, medullary substance; c,
which enters with the larger blood- cortical substance with indistinct alveoli ;
vessels at the hilus, and surrounds d, capsule (alter Kolliker).
them together with the lymph-ves-
sels, in the centre of the gland, so that the medullary part is reduced to
a layer of no great thickness bounding inwardly the cortical part.
Throughout both its cortical and medullary part the gland is pervaded by
a trabecular frame-work which incloses and supports the proper glandular
substance. The trabeculse pass inwards from the capsule. They consist,
in the ox, chiefly of plain muscular tissue ; in man, of connective tissue,
sparingly intermixed with muscular fibre-cells. In the cortical part they
are mostly lamellar in form, and divide the space into small compartments,
alveoli, from ^L- to -^ of an inch wide, which communicate laterally
with each other through openings in the imperfect partitions between them
(fig. cm. A). On reaching the medullary part the trabeculse take the form
of flattened bands or cords, and by their conjunction and reticulation form
a freely intercommunicating mesh work throughout the interior. (In the
figures they are represented mostly as cut across.) In these alveoles and
meshes is included the proper glandular substance, which appears as a tole-
rably firm pulp, or parenchyma. In the alveoli of the cortical part this
forms rounded nodules (fig. cm. AC?); in the trabecular meshes of the
medullary part it takes the shape of rounded cords joining in a corre-
sponding network (figs. cm. B d ; civ. a a) ; and, as the containing meshes
communicate, so the contained gland -pulp is continuous throughout. But
both in the cortical alveoles and the medullary trabecular meshes, a narrow
space (left white in the figs. cm. I ; civ., cv. 6) is left all round the gland-
pulp, between it and the alveolar partitions and trabecular bands, like what
would be left had the pulp shrunk away from the inside of a mould in which
it had been cast. This space is both a receptacle and a channel of pas-
sage for the lymph that goes through the gland ; it is the lymph-sinus
clxxxviii LYMPHATIC SYSTEM.
(His), or the lymph- channel. It is traversed by retiform connective tissue
(fig. cv. c c), in which the nuclei of the spindle-shaped or ramified cells are
mostly apparent, and is filled with fluid lymph, containing many lymph-
corpuscles, which may be washed out from sections of the gland with a hair
pencil, so' as to show the sinus, while the firmer gland-pulp, which the sinus
surrounds, keeps its place. The latter, the proper glandular substance, is
also pervaded and supported by retiform tissue, mostly non-nucleated (fig.
cv. a), communicating with that of the surrounding lymph-sinus, but
marked off from it by somewhat closer reticulation at their mutual
boundary, not so close, however, as to prevent fluids, or even solid cor-
puscles, from passing from the one to the other. This glandular pulp is
made up of densely packed lymph-corpuscles, occupying the interstices of
Fig. GUI.
* & B
Fig. CIII. SECTION OF A MESENTERIO GLAND OF THE Ox (magnified 12 diameters).
The section includes a portion of the cortical part, A, in its whole depth, and a smaller
portion of the adjoining medullary part, B ; c, c, outer coat or capsule sending partitions
into the cortical part to form alveoli, and trabeculse, tt, which are seen mostly cut across ;
d d, the glandular substance forming nodules in the cortical part, A, and reticulating
cords in the medullary part, B ; ?, Z, lymph-sinus or lymph'shannel, left white (after His).
its supporting retiform tissue, and is traversed by an abundant network of
capillary blood-vessels, which runs throughout the proper glandular pulp,
both cortical and medullary, but does not pass into the surrounding lymph-
sinus. Arteries enter and veina leave the gland at the hilus, surrounded,
in some glands, as already said, with a dense inclosure of connective tissue.
The arterial branches go in great part directly to the glandular substance,
but partly also to the trabeculse. The former end in the glandular capil-
lary network above-mentioned, from which the veins begin, and tend to the
hilus alongside the arteries. The branches to the trabeculte run upon these
bands, and are in part conducted to the coat of the gland to be there dis-
tributed ; some of them in an indirect way reach the glandular substance.
The blood-vessels of the gland-pulp are supported by its pervading retiforra
tissue, which is not only connected to them, but forms an additional or
LYMPHATIC GLAXDS.
clxxxix
adventitious coat round their small branches, and even on some of the
capillaries (page clxxix).
Fig. CV.
Fig. CIV.
Fig. CIV. SECTION OF MEDULLARY SUDSTANCE OP AN INGUINAL GLAND OP THE Ox
(magnified 90 diameters).
a, a, glandular substance or pulp forming rounded cords joining in a continuous net
(dark in the figure) ; c, c, trabeculae ; the space, b, b, between these and the glandular
substance is the lymph-sinus, washed clear of corpuscles and traversed by filaments of
retiform connective tissue (after Kb'lliker).
Fig. CV. A VERT SMALL PORTION OP THE MEDULLARY SUBSTANCE FROM A MESENTERIO
GLAND OF THE Ox (magnified 300 diameters).
d, d, trabeculse ; a, part of a cord of glandular substance from which all but a few of
the lymph-corpuscles have been washed out to show its supporting meshwork of retiform
tissue and its capillary blood-vessels (which have been injected, and are dark in the
figure) ; >, 6, lymph-sinus, of which the retiform tissue is represented only at c, c (after
Kolliker).
As to the lymphatics of the gland, it seems now to be tolerably well
made out, that the afferent vessels, after branching out upon and in the
tissue of the capsule, send their finer branches through it to open into the
lymph-sinuses of the cortical alveoli, and that the efferent lymphatics begin
by fine branches leading from the lymph-sinuses of the medullary part, and
forming at the hilus a dense plexus of tortuous and varicose-looking vessels,
from which branches proceed to join the larger efferent trunks. The lymph-
sinus, therefore, forms a channel for the passage of the lymph, interposed
between the afferent and efferent lymphatics, communicating with both,
and maintaining the continuity of the lymph-stream. The afferent and
efferent vessels, where they open into the lymph-sinus, lay aside all their
coats, except the epithelium, and the sinus is lined throughout its whole
extent with a similar epithelium, consisting, as in the commencing lymph-
lacuna, of a single layer of flattened cells.
cxc LYMPHATIC SYSTEM.
It is not unreasonable to presume that, in the proper glandular substance, there is
a continual production of lymph-corpuscles, most probably by fissiparous multiplica-
tion, which pass into the lymph-sinus, and that fresh corpuscles are thus added to the
lymph as it passes through a gland ; and this view is supported by the fact, that the
corpuscles are found to be more abundant in the lymph or chyle after it has passed
through the glands (see page L). It has been alleged, moreover, that the lymph,
after passing the glands, is richer in fibrin, and therefore coagulates more firmly. In
any case, it is plain that the numerous blood-capillaries distributed in a gland must
bring the blood into near relation with the elements of the lymph; and the latter
fluid, as it must move very slowly through the relatively wide space within the gland,
is thus placed in a most favourable condition for some not improbable interchange of
material with the blood.
Termination. The absorbeut system discharges its contents into the
veins at two points, namely, at the junction of the subclaviau and internal
jugular veins of the left side by the thoracic duct, and at the corresponding
part of the veins of the right side by the right lymphatic trunk. The
openings, as already remarked, are guarded by valves. It sometime i
happens that the thoracic duct divides, near its termination, into two or
three short branches, which open separately, but near each other ; more
rarely, a branch opens into the vena azygos indeed the main vessel has
been seen terminating in that vein. Again, it is not uncommon for larger
branches, which usually join the thoracic duct, to open independently in
the vicinity of the main termination ; and this is more apt to happen with
the branches which usually unite to form the right lymphatic trunk. By
such variations the terminations in the great veins are multiplied, but still
they are confined in man to the region of the neck ; in birds, reptiles, and
fish., on the other hand, communications take place between the lymphatics
of the pelvis, posterior extremities and tail, and the sciatic or other con-
siderable veins of the abdomen or pelvis.
The alleged terminations of lymphatics in various veins of the abdomen, described
by Lippi as occurring in man and mammalia, have not been met with by those who
have since been most engaged in the prosecution of this department of anatomical re-
search, and accordingly his observations have generally been either rejected as
erroneous, or held to refer to deviations from the normal condition.* But, while such
(extraglandular) terminations in other veins than those of the neck have not been
generally admitted, several anatomists of much authority have maintained that the
lacteals and lymphatics open naturally into veins within the lymphatic glands. This
latter opinion, which has been strenuously advocated by Fohnaann in particular, is
based on a fact well knoAvn to every one conversant with the injection of the
vessels in question, namely, that the quicksilver usually employed for that purpose,
when it has entered a gland by the inferent lymphatics, is apt to pass into branches of
veins within the gland, and thus finds its way into the large venous trunks in the
neighbourhood, in place of issuing by the efferent lymphatic vessels. But, although
it, of course, cannot be doubted that, in such cases, the mercury gets from the
lymphatics into the veins, no one has yet been able to perceive the precise mode in
which the transmission takes place ; and, looking to the circumstances in which it
chiefly occurs, it seems to be more probably owing to rupture of contiguous lymphatics
and veins within the glands, than to a natural communication between the two classes
of vessels in that situation.
Lymphatic heart*. Miiller and Panizza, nearly about the same time, but inde-
pendently of each other, discovered that the lymphatic system of reptiles is furnished,
at its principal terminations in the venous system, with pulsatile muscular sacs,
* In a communication inserted in Miiller's Archiv for 1848, p. 173, Dr. Nutm, of
Heidelberg, affirms the regular existence of these abdominal terminations, and refers to
three instances which he met with himself. In two of these, the lymphatics opened into
the renal veins, and in the other into the vena cava.
SEROUS MEMBRANES. cxci
which serve to discharge the lymph into the veins. These organs, which are named
lymph-hearts, have now been found in all the different orders of reptiles. In frogs
and toads two pairs have been discovered, a posterior pair, situated in the sciatic
region, which pour their lymph into a branch of the sciatic or of some other neigh-
bouring vein, and an anterior more deeply seated pair, placed over the transverse
process of the third vertebra, and opening into a branch of the jugular vein. The
parietes of these sacs are thin and transparent, but contain muscular fibres of the
striated kind, freely ramifying, decussating in different layers, as in the blood-heart.
In their pulsations they are quite independent of the latter organ, and are not even
synchronous with each other. In salamanders, lizards, serpents, tortoises, and
turtles, only a posterior pair have been discovered, which, however, agree in all
essential points with those of the frog. In the goose, and in other species of birds
belonging to different orders, Panizza discovered a pair of lymph sacs opening into
the sacral veins, and Stannius has since found that these sacs have striated muscular
fibres in their parietes; but, although this observer, in some cases, exposed them
in the living bird, he was not able to discover any pulsation or spontaneous movement
in them. Nerve-fibres, both dark bordered and pale, have been observed in the
lymph-hearts of the frog, and also nerve-cells in those of the common tortoise.
(Waldeyer.)
Development of lymphatic r&sels. Kb'lliker has observed the formation of lym-
phatics from ramified cells in the tails of young salamander-larvae. He states that the
process takes place nearly in the same manner as in the case of sanguiferous capillaries;
the only notable difference being, that whilst the growing lymphatics join the ramified
cells, and thus extend themselves, their branches very rarely anastomose or become
connected by communicating arches. The soundness of his conclusions has, however,
been called in question and the subject requires further elucidation. New-formed
lymphatics have been injected in adhesions between inflamed serous membranes.
SEROUS MEMBRANES.
The serous membranes are so named from the apparent nature of the fluid
with which their surface is moistened. They line cavities of the body which
have uo outlet, and the chief examples of them are, the peritoneum, the
largest of all, lining the cavity of the abdomen ; the two pleurae and peri-
cardium in the chest ; the arachnoid membrane in the cranium and verte-
bral canal ; and the tunica vaginalis surrounding each of the testicles
within the scrotum.
Form and arrangement. In all these cases the serous membrane has the
form of a closed sac, one part of which is applied to the w.Jls of the cavity
which it lines, the parietal portion ; whilst the other is reflected over the
surface of the organ or organs contained in the cavity, and is therefore
named the reflected or visceral portion of the membrane. Hence the viscera
in such cavities are not contained within the sac of the serous membrane,
but are really placed behind or outside of it ; merely pushing inwards, as
it were, the part of the membrane which immediately covers them, some
organs receiving in this way a complete, and others but a partial and some-
times very scanty investment.
In passing from one part to another, the membrane frequently forms
folds which in general receive the appellation of ligaments, as, for example,
the folds of peritoneum passing between the liver and the parietes of the
abdomen, but which are sometimes designated by special names, as in the
instances of the mesentery, meso-colon, and omeutum.
The peritoneum, in the female sex, is au exception to the rule that
serous membranes are perfectly closed sacs, inasmuch as it has two
openings by which the Fallopian tubes communicate with its cavity.
A serous membrane sometimes lines a fibrous membrane, as where the
arachnoid lines the dura mater, or where the serous layer of the peri-
cxcii SEROUS MEMBRANES.
cardium adheres to its outer or 6brous part. Such a combination is often
named a fibro-serous membrane.
The inner surface of a serous membrane is free, smooth, and polished ;
and, as would occur with an empty bladder, the inner surface of one part
of the sac is applied to the corresponding surface of some other part ; a
small quantity of fluid, usually not more than merely moistens the con-
tiguous surfaces, being interposed. The parts situated in a cavity lined by
serous membrane can thus glide easily against its parietes or upon each
other, and their motion is rendered smoother by the lubricating fluid.
The outer surface most commonly adheres to the parts which it lines or
covers, the connection being effected by means of areolar tissue, named
therefore " subserous," which, when the membrane is detached, gives to its
outer and previously adherent surface a flocculent aspect. The degree of
firmness of the connection is very various : in some parts, the membrane
can scarce be separated ; in others, its attachment is so lax as to permit
easy displacement. The latter is the case in the neighbourhood of the
openings through which abdominal herniae pass ; and accordingly, when such
protrusions of the viscera happen to take place, they usually push the peri-
toneum before them in form of a hernial sac.
The visceral portion of the arachnoid membrane is in some measure an
exception to the rule of the outer surface being everywhere adherent; for, in
the greater part of its extent, it is thrown loosely round the parts which it
covers, a few fine fibrous bands being the sole bond of connection ; and a
quantity of pellucid fluid is interposed, especially in the vertebral canal and
base of the cranium, between the arachnoid and the pia mater, which is the
membrane immediately investing the brain and spinal cord.
Structure and properties. Serous membranes are thin and transparent, so
that the colour of subjacent parts shines through them. They are tolerably
strong, with a moderate degree of extensibility and elasticity. They con-
sist of, 1st, a simple layer of scaly epithelium already described and figured
(fig. xx.), which, however, is in part ciliated on the serous membrano
lining the ventricles of the brain and central canal of the spinal cord ; 2ndly,
the fibrous layer. This consists of fine but dense areolar connective tissue,
which is, as usual, made up of bundles of white filaments mixed with fine elastic
fibres ; the former, when there are two or more strata, take a different direc-
tion in the different planes ; the latter unite into a network, and, in many
serous membranes, as remarked by Henle, are principally collected into a
reticular layer at the surface, immediately beneath the epithelium. Tho
constituent connective tissue of the serous membrane is of course continuous
with the usually more lax subserous areolar tissue connecting the mem-
brane to the subjacent parts. Where the arachnoid membrane lines the
dura mater, and possibly al?o in some other cases, the fibrous layer
usually belonging to the serous membrane is wanting, its place being sup-
plied by the fibrous membrane beneath, on which the epithelium is imme-
diately applied.
Blood-vessels ending in a capillary network with comparatively wide meshes
pervade the subserous tissue and the tissue of the serous membrane. Plex-
uses of lymphatics also exist in the subserous tissue, but not under every
part of the membrane ; in the costal pleura, for example, the lymphatics are
confined to the parts which cover the intercostal and stemo-co: tal muscles.
When present, the lymphatics extend in form of fine superficial plexuses
through the fibrous layer of the membrane to its surface, immediately
beneath the epithelium (Dybkowski), and may then open into the serous
SYNOVIAL MEMBRANES. cxciii
cavity by cognisable apertures, as already stated. Fine nervous fibres,
with nerve-cells in some places, have been described by several auatoniists,
in or immediately beneath the serous membranes of various regions ; never-
theless it would seem, that when in a healthy condition these membranes
possess little or no sensibility ; they are altogether devoid of vital contractility.
Fluid. The internal surface of serous cavities is moistened and lubricated with a
transparent and neaily colourless fluid, which in health exists only in a very small
quantity. This fluid, which is doubtless derived from the blood-vessels of the mem-
brane, has been commonly represented as similar in constitution to the serum of the
blood. But it was long since remarked by Hewson (and a similar opinion seems to
have been held by Haller and Monro), that the fluid obtained from the serous cavities
of recently killed animals coagulates spontaneously, and thus resembles the lymph of
the lymphatic vessels, and, we may add, the liquor sanguinis or plasma of the blood,
the coagulation being, of course, due to the presence of fibrin, or of its two con-
stituents fibrinogen and globulin. Hewson, who regarded the fluid as lymph,
found that the coagulability diminished as the quantity increased. In confirmation of
Hewson's statement, I may mention that I have always found the fluid obtained from
the peritoneal cavity of rabbits to coagulate spontaneously in a greater or less degree.
Hewson made his observations on the fluid of the peritoneum, pleura, and pericardium,
in various animals, viz., bullocks, dogs, geese and rabbits.*
"When the fluid gathers in unusual quantity as in dropsies, it rarely coagulates spon-
taneously on being let out ; but will often yield a coagulum on the addition of globulin
as already stated (page xxxviii.). From this it may be inferred that fibrinogen is
present, but not the globulin (fibrino-plastin) requisite to generate fibrin.
The identity in character of the fluid of serous cavities and the lymph-plasma is, it
need scarcely be remarked, in keeping with the notion of their being great lymph-
spaces in open connection with lymphatic vessels. But this view is quite reconcilable
with the mechanical purpose commonly ascribed to these membranes, of lubricating
and facilitating the movement of mutually opposed surfaces.
When a serous membrane is inflamed, it has a great tendency to throw out coagu-
lable lymph (or fibrin) and serum, the two constituents of the blood-plasma, the
former chiefly adhering to the inner surface of the membrane, whilst the latter
gathers in its cavity. The coagulable lymph spread over the surface, in form of a
" false membrane," as it is called, or agglutinating the opposed surfaces of the serous
sac and causing adhesion, becomes pervaded by blood-vessels, and in process of time
converted into areolar tissue.
Breaches of continuity in these membranes are readily repaired, and the new-formed
portion acquires all the characters of the original tissue.
SYNOVIAL MEMBRANES.
Resembling serous membranes in general form and structure, the synovial
membranes are distinguished by the nature of the secretion which lubricates
their surface, for this is a viscid glairy fluid resembling the white of an egg,
and thence named synovia.
These membranes line the cavities of joints, and are interposed between
moving parts in certain other situations ; being in all cases intended to
lessen friction, and thereby facilitate motion. They are composed of a scaly
epithelium, which may consist of several strata, and a layer of dense
areolar tissue pervaded by vessels and attached by tissue of the same kind
to the parts beneath.
The different synovial membranes of the body are referred to three classes,
viz., articular, vesicular, and vacjinal.
1. Articular synovial membranes, or Synovial capsules of joints. These
* See Hewson's Works, published by the SydenLam Society, p. 157, with some
important remarks in notes xviii. and Ixviii., by the editor, Mr. Grulliver.
cxciv SYXOVIAL MEMBRANES.
line and by their synovial secretion lubricate the cavities of the diar-
throdial articulations, that is, those articulations in which the opposed
surfaces glide on each other. In these cases the membrane may be
readily seen covering internally the surface of the capsular or other
ligaments which bound the cavity of the joint, and affording also an
investment to the tendons or ligaments which happen to pass through
the articular cavity, as in the instance of the long tendon of the
biceps muscle in the shoulder-joint. On approaching the articular
cartilages the membrane passes over their margins, and, becoming much
more firmly adherent, terminates after advancing hut a litrle way on their
surface. This, as already explained (page Ixxxiii. ), is the condition in the
adult ; but in the foetus the membrane, closely adhering, is continued over
the whole surface of the cartilage, so that it would seem to become oblite-
rated or absorbed in consequence of pressure or friction when the joint
comes to be exercised. The blood-vessels in and immediately underneath the
membrane are sufficiently manifest in most parts of the joint. They advance
but a little way upon the cartilages, forming a vascular zone round the
margin of each, named " circulus articuli vasculosus," in which they end by
loops of vessels dilated at the bent part greatly beyond the diameter of
ordinary capillaries. In the fostua, according to Mr. Toynbee, these
vessels, like the membrane itself, advance further upon the surface of the
cartilage.
In several of the joints, folds of the synovial membrane, often containing more or
less fat, pass across the cavity ; these have been called synovial or mucous ligaments.
Other processes of the membrane simply project into the cavity at various points.
These are very generally cleft into fringes at their free border, upon which their blood-
vessels, which are numerous, are densely distributed. They often contain fat, and
then, when of tolerable size, are sufficiently obvious ; but many of them are very small
and inconspicuous. The fringed vascular folds of the synovial membrane were
described, by Dr. Clopton Havers (1691), under the name of the mucilaginous glands,
and he regarded them as an apparatus for secreting synovia. Subsequent anatomists,
while admitting that, as so many extensions of the secreting membrane, these folds
must contribute to increase the secretion, have, for the rno.st part, denied them the
special character of glands, considering them rather in the light of a mechanical pro-
vision for occupying spaces which would otherwise be left void in the motion of the
joints, and this view is no doubt right as regards the larger, fat-inclosing folds.
The smaller and less obvious fringes have, however, been found, on investigation by
Mr. Rainey, to be most probably secreting organs as originally supposed by Havers.
Mr. Rainey* has found that the processes in question exist in the bursal and vaginal
synovial membranes as well as in those of joints, wherever, in short, synovia is secreted.
He states that their blood-vessels have a peculiar convoluted arrangement, differing
from that of the vessels of fat, and that the epithelium covering them, "besides in-
closing separately each packet of convoluted vessels, sends off from each tubular sheath
secondary processes of various shapes, into which no blood-vessels enter." Kb'lliker,
who has since taken up the inquiry, also finds that fringed membranes exist in all
joints and synovial sheaths, as well as in most synovial bursse, and that they consist
of vascular tufts of the synovial membrane, covered by epithelium, and now and then
containing fat-cells and more rarely isolated cartilage cells. He also observed the
curious " non-vascular secondary processes," described by Mr. Rainey, the larger of
which, he says, consist of fibres of areolar tissue in the centre, sometimes containing
cartilage-cells, and a covering of irregularly thickened epithelium.
2. Vesicular or Bursal synovial membranes, Synovial bursce, Bursce mucosce.
In these the membrane has the form of a simple sac, interposed, so as to
prevent friction, between two surfaces which move upon each other. The sy-
* Proceedings of the Royal Society, May 7th, 1846.
MUCOUS MEMBRANES. cxcv
nov'al sac in such cases is flattened and has its two opposite sides in apposi-
tion by their inner surface, which is free and lubricated with synovia, whilst
the outer surface is attached by areolar tissue to the moving parts between
which the sac is placed. As in the case of articular synovial membranes,
the bursal membrane on the rubbing surfaces may be, at parts, obliterated.
In point of situation, the bursee may be either deep-seated or subcutaneous.
The former are for the most part placed between a muscle or its tendon and a
bone or the exterior of a joint, less commonly between two muscles or tendons :
certain of the bursae situated in the neighbourhood of joints not unfre-
quently open into them. The subcutaneous bursae lie immediately under the
skin, and are found in various regions of the body interposed between the
skin and some firm prominence beneath it. The large bursa situated over
the patella is a well-known example of this class, but similar though
smaller bursse are found also over the olecranon, the malleoli, the knuckles,
and various other prominent parts. Tt must, however, be observed that,
among these subcutaneous bursae, some are reckoned which do not always
present the characters of true synovial sacs, but look more like mere recesses
in the subcutaneous areolar tissue, larger and more defined than the neigh-
bouring areolse, but still not bounded by an evident synovial membrane.
These have been looked on as examples of less developed structure,
forming a transition between the areolar tissue and perfect synovial mem-
brane.
3. Vaginal Synovial membranes or Synovial sheaths. These are intended
to facilitate the motion of tendons as they glide in the fibrous sheaths which
bind them down against the bones in various situations. The best-marked
examples of such fibrous sheaths are to be seen in the hand and foot, and
especially on the palmar aspect of the digital phalanges, where they confine
the long tendons of the flexor muscles. In such instances one part of the
pynovial membrane forms a lining to the osseo-fi^rous tube in which the
tendon runs, and another part is reflected at each end upon the tendon, and
affords it a close investment. The space between the parietal and re-
flected portions of the membrane is lubricated with synovia and crossed
obliquely by one or more folds or duplications of the membrane, in some
parts inclosing elastic tissue. These are named "frsena," and pass from one
part of the membrane to the other.
Synovia. As already stated, this is a viscid transparent fluid; it has a yellowish
or faintly reddish tint, and a slightly saline taste. According to Frerichs, the synovia
of the ox consists of 94 - 85 water, 0'56 mucous and epithelium, 0'07 fat, 3'51 albumen
and extractive matter, and 0'99 salts. If a drop of synovial fluid be examined micro-
scopically, it is found to contain (in addition to fat-molecules and epithelium-cells)
small, granular corpuscles, bearing a close re-emblance to the pale corpuscles of the
blood. It is doubtful whether these bodies have a special nature and purpose, or
whether they are merely transitory forms of epithelium-particles.
MUCOUS MEMBRANES.
These membranes, unlike the serous, line internal passages, and other
cavities which open on the surface of the body, as well as various recesses,
sinuses, gland-ducts and receptacles of secretion, which open into such pas-
sages. They are habitually subject to the contact of foreign substances
introduced into the body, such as air and aliment, or of various secreted or
excreted matters, and hence their surface is coated over and protected by
mucus, a fluid of a more consistent and tenacious character than that which
moistens the serous membranes.
cxcvi MUCOUS MEMBRANES.
The mucous membranes of several different or even distant parts are con-
tinuous, and, with certain unimportant reservations, to be afterwards ex-
plained, they may all be reduced to two great divisions, namely, the gastro-
pulmonary and genito-urinary. The former covers the inside of the alimen-
tary and air-passages as well as the less considerable cavities communicating
with them. It may be described as commencing at the edges of the lips and
nostrils, where it is continuous with the skin, and proceeding through the
nose and mouth to the throat, whence it is continued throughout the whole
length of the alimentary canal to the termination of the intestine, there
again meeting the skin, and also along the windpipe and its numerous
divisions as far as the air-cells of the lungs, to which it affords a lining.
From the nose the membrane may be said to be prolonged into the lach-
rymal passages, extending up the nasal duct into the lachrymal sac and along
the lachrymal canals until, under the name of the conjuuctival membrane,
it spreads over the fore part of the eyeball and inside of the eyelids, on the
edges of which it encounters the skin. Other offsets from the nasal part of
the membrane line the frontal, ethmoidal, sphenoidal and maxillary sinuses,
and from the upper part of the pharynx a prolongation extends on each side
along the Eustachian tube to line that passage and the tympanum of the ear.
Besides these, there are offsets from the alimentary membranes to line the
lachrymal, salivary, pancreatic, and biliary ducts, and the gall-bladder. The
genito-urinary membrane invests the inside of the urinary bladder and the
whole tract of the urine in both sexes, from the interior of the kidneys to
the orifice of the urethra, also the seminal ducts and vesicles in the male,
and the vagina, uterus, and Fallopian tubes in the female.
The mucous membranes lining the ducts of the mammary glands,
being unconnected with either of the above-mentioned great tracts, have
sometimes been enumerated as a third division ; and the number might
of course be multiplied, were we separately to reckon the membranes pro-
longed from the skin into the ducts of the numerous little glands which
open on the surface of the body.
The mucous membranes are attached by one surface to the parts which
they line or cover by means of areolar tissue, named " submucous," which
differs greatly in quantity as well as in consistency in different parts. The
connection is in some cases close and firm, as in the cavity of the nose
and its adjoining sinuses ; in other instances, especially in cavities sub-
ject to frequent variation in capacity, like the gullet and stomach, it is lax
and allows some degree of shifting of the connected surfaces. In such
cases as the last-mentioned the mucous membrane is accordingly thrown
into folds when the cavity is narrowed by contraction of the exterior
coats of the organ, and of course these folds, or rugce, as they are
named, are effaced by distension. But in certain parts the mucous mem-
brane forms permanent folds, not capable of being thus effaced, which pro-
ject conspicuously into the cavity which it lines. The best-marked example
of these is presented by the valvulce conniventes seen in the small intestine.
These, as is more fully described in the special anatomy of the intestines,
are cresceut-shaped duplicatures of the membrane, with connecting areolar
tissue between their laminae, which are placed transversely and follow one
another at very short intervals along a great part of the intestinal tract.
The chief purpose of the valvulae conniventes is doubtless to increase the
surface of the absorbing mucous membrane within the cavity, and it has
also been supposed that they serve mechanically to delay the alimentary
mass in its progress downwards. A mechanical office has also been as-
STRUCTURE. cxcvii
signed to a scries of oblique folds of a similar permanent kind, though
on a smaller scale, which exist withiu the cystic duct.
Physical properties. In most situations the mucous membranes are
nearly opaque or but slightly translucent. They possess no great degree
of tenacity and but little elasticity, and hence are readily t->rn by a mo-
derate force. As to colour, they cannot be said intrinsically to have any,
and when perfectly deprived of blood they accordingly appear white or at
most somewhat grey. The redness which they commonly exhibit during
life, and retain in greater or less degree in various parts after death, is
due to the blood contained in their vessels, although it is true that, after
decomposition has set in, the red matter of the blood, becoming dissolved,
transudes through the coats of the vessels, and gives a general red tinge to
the rest of the tissue. The degroe of redness exhibited by the mucous mem-
branes after death is greater in the foetus and infant than in the adult. It
is greater too in certain situations ; thus, of the different parts of the
alimentary canal, it is most marked in the stomach, pharynx, and rectum.
Again, the intensity of the tint, as well as its extent, is influenced by cir-
cumstances accompanying or immediately preceding death. Thus the state
of inflammation, or the local application of stimuli to the membrane, such as
irritant poisons, or even food in the stomach, is apt to produce increased
redness ; and all the mucous membranes are liable to be congested with
blood and suffused with redness when death is immediately preceded by
obstruction to the circulation, as in cases of asphyxia, and in many diseases
of the heart.
Structure,. A mucous membrane is composed of corium and epithe-
lium. The epithelium covers the surface, and has already been described
(p. iii., et sqq.). The membrane which remains after removal of the epi-
thelium is named the corium, as in the analogous instance of the true
skin. The corium may be said to consist of a fibro-vascular layer , of vari-
able thickness, bounded superficially or next the epithelium by an ex-
tremely fine transparent lamella, named basement-membrane by Bowman,
and primary membrane, limitary membrane, and membrana propria by
others who have described it. It must be explained, however, that these
two constituents of the corium cannot in all situations be separated from
each other, nor indeed can the presence of both be proved by actual demon-
stration in all parts of the mucous membranes.
The basement-membrane is best seen in parts where the mucous membrane
is raised into villous processes or where it forms secreting crypts or minute
glandular recesses, such as those which abound in the stomach and intes-
tinal canal. On teasing out a portion of the gastric or intestinal mucous
membrane under the microscope, some of the tubular glands are here and
there discovered which are tolerably well cleared from the surrounding
tissue, and their parietes are seen to be formed of a thin pellucid film,
which is detached from the adjoining fibro- vascular layer, the epithelium
perhaps still remaining in the inside of the tube or having escaped, as the
case may be. The fine film referred to is the basement-membrane. It may
by careful search be seen too on the part of the corium situated between
the orifices of the glands, and on the villi, when the epithelium is detached,
although it cannot be there separated from the vascular layer. In these
parts it manifestly forms a superficial boundary to the corium, passing
continuously over its eminences and into its recesses, defining its surface,
and supporting the epithelium. In other parts where villi and tubular
glands are wanting, and especially where the mucous membrane, more
cxcviii MUCOUS MEMBRANES.
simply arranged, presents an even surface, as in the tympanum and nasal
sinuses, the basement-membrane is absent, at least not demonstrated. In
such situations it may possibly have originally existed as a constituent of
the corium, and have been obliterated or rendered inconspicuous in conse-
quence of subsequent modifications.
The basement-membrane, as already said, forms the peripheral boundary
of the corium ; it is in immediate connection with the epithelium. By its
under surface it more or less closely adjoins the fibro-vascular layer. The
vessels of the latter advance close up to the basement-membrane, but no-
where penetrate it ; the delicate film of which it consists is indeed wholly
extravascular. In structure the membrane in question seems perfectly
homogeneous, but marks resembling the nuclei of epithelium-cells are some-
times seen disposed evenly over its surface, and some observers, considering
these as forming an integrant part of the membrane, have looked on them
as so many reproductive centres from which new epithelium-particles are
generated. Mr. Bowman, on the other hand, considers these objects as
nuclei belonging to the undermost and as it were nascent epithelium-cells,
which have remained adherent to the really simple basement-membrane.
The fibro-vascular layer of the corium is composed of vessels both sangui-
ferous and lymphatic, with fibres of connective tissue, and, in many parts,
of non-striated muscular tissue, variously disposed. The nerves also which
belong to the mucous membrane are distributed in this part of its structure.
The vessels exist universally in mucous membranes, except in that which
covers the anterior surface of the cornea ; there the epithelium and base-
ment-membrane are present, but, in the adult, no vessels except at the
border. Elsewhere the branches of the arteries and veins, dividing in the
submucous tissue, send smaller branches into the corium, which at length
form a network of capillaries in the fibro-vascular layer. This capillary
network lies immediately beneath the epithelium, or the basement-mem-
brane when this is present, advancing with that membrane into the villi
and papillse to be presently described, and surrounding the tubes and other
glandular recesses, into which it is hollowed. The lymphatics also form
networks, which communicate with plexuses of larger vessels in the sub-
mucous tissue ;~ their arrangement generally, as well as in the villi, has
been already noticed.
The fibres of connective tissue which enter into the formation of the corium
are both the white and the elastic. The former are arranged in interlacing
bundles, the elastic commonly in networks ; but the amount of both is very
different in different parts. In some situations, as in the gullet, windpipe,
bladder, and vagina, the connective tissue is abundant, and extends
throughout the whole thickness of the fibro-vascular layer, forming a con-
tinuous and tolerably compact web, and rendering the mucous membrane of
those parts comparatively stout and tough. In the stomach and intestines,
on the other hand, where the membrane is more complex, and at the same
time weaker in structure, the elastic fibres are wanting and the white con-
nective tissue is in small proportion ; its principal bundles follow and sup-
port the blood-vessels, deserting, however, their finer and finest branches
which lie next the basement membrane ; and accordingly there exists, for
some depth below this membrane, a stratum of the corium in which very
few if any filaments of the common areolar tissue are seen. In this stratum
of the gastro-enteric mucous membrane, the tubular glands with their
lining epithelium are set, and between and around them the numerous
sanguiferous capillaries and lymphatic vessels are distributed ; but the sub-
STRUCTURE.
Fig. CVI.
stance of the membrane in which these parts lie is constructed of the variety
of connective tissue known as cytogenous or retiform (p. Ixxix, fig. xxxvm.),
which is formed of ramified and reticularly connected corpuscles, with or
without nuclei persistent at the points whence the branches divaricate ;
and in the meshes of this tissue is con-
tained a profusion of granular bodies
having all the characters of pale blood-
or lymph-corpuscles. This structure
(fig. CVL), which prevails in the mucous
membrane of the stomach and intes-
tines, both large and small, is some-
times named lymplioid tissue from its
resemblance to the interior tissue of
the lymphatic glands and of other
bodies belonging to or supposed to
belong to the lymphatic system, and
especially those known as the solitary
and agminated glands of the alimen-
tary mucous membrane. The tissue
forming the last-named bodies, indeed,
is often continuous with the lymphoid
tissue in their vicinity. The deepest
layer of the alimentary mucous mem-
brane, from the commencement of the
cesophagus downwards, is formed
throughout by non-striated muscular
tissue, and is named muscularis mucosce.
This lies next to the submucous tissue,
and consists of bundles running in
many parts both longitudinally and
circularly, in others in one of these
directions only. Prolongations from it
pass up between the glands to be distributed in the villi.
The free surface of the mucous membranes is in some parts plain, but in
others is beset with little eminences named papillae and villi. The papillae
are best seen on the tongue ; they are small processes of the corium, mostly
of a conical or cylindrical figure, containing blood-vessels and nerves, and
covered with epithelium. Some are small and simple, others larger and
compound or cleft into secondary papillae. They serve various purposes ;
some of them no doubt minister to the senses of taste and touch, many
appear to have chiefly a mechanical office, while others would seem intended
to give greater extension to the surface of the corium for the production of
a thick coating of epithelium. The villi are most fully developed on the
mucous coat of the small intestines. Beiog set close together like the pile
or nap of cloth, they give to the parts of the membrane which they cover
the aspect usually denominated " villous." They are in reality little
elevations or processes of the superficial part of the corium, covered with
epithelium, and containing blood-vessels and lacteals, which are thus favour-
ably disposed for absorbing nutrient matters from the intestine. The more
detailed description of the papillae and villi belongs to the special anatomy
of the parts where they occur.
In some few portions of the mucous membrane the surface is marked
with fine ridges which intersect each other in a reticular manner, and thus
o 2
Fig. CVI. LYMPHOID OR RETIFORM
TISSUE OF THK INTESTINAL Mucous
MEMBRANE OF THE SHEEP (from Frey).
MAGNIFIED 400 DIAMETERS.
Cross section of a small fragment of
the mucous membrane, including one
entire crypt of Lieberkiihn and parts of
several others : a, cavity of the tubular
glands or crypts ; 6, one of the lining
epithelial cells ; c, the lymphoid or reti-
form spaces, of which some are empty,
and others occupied by lymph -cells as
atd.
cc MUCOUS MEMBRANES.
inclose larger and smaller polygonal pits or recesses. This peculiar cha-
racter of the surface of the membrane, which might be called " alveolar,"
is seen very distinctly in the gall-bladder, and on a finer scale in the vesi-
culse seminales ; still more minute alveolar recesses with intervening ridges
may be discovered with a lens on the mucous membrane of the stomach
(fig. evil.).
Glands of mucous membranes. Many, indeed
Fig. CVII. most, of the glands of the body pour their
secretions into the great passages lined by
mucous membranes ; but there are certain
small glands which may be said to belong to
the membrane itself, inasmuch as they are
found in numbers over large tracts of that mem-
brane, and yield mucus, or special secretions
known to be derived from particular portions of
the membrane. Omitting local peculiarities the
Fig. CYir. PORTION OP Mu- glands referred to may be described as of three
cous MEMBRANE OF THE w d j
STOMACH, SLIGHTLY MAG- ' 7 , . 7 m . . . .
NIFIED. The alveolar pits * Tubular glands. These are minute tubes
and small orifices of the formed by recesses or inversions of the base-
tubular glands are seen ment membrane, and lined with epithelium.
They are usually placed perpendicularly to the
surface, and often very close together, and
they constitute the chief substance of the mucous membrane in those
parts where they abound, its apparent thickness depending on the length
of the tubes, which differs considerably in different regions. The tubes
open by one end on the surface ; the other end is closed, and is either
simple or loculated, or even cleft into two or more branches. The tubular
glands are abundant in the stomach, and in the small and large intestines,
where they are comparatively short and known as the crypts of Lieber-
kiihn. They exist also in considerable numbers in the mucous membrane
of the uterus.
2. Small compound glands. Under this head are here comprehended
minute but still true compound glands of the racemose kind, with single
branched ducts of various lengths, which open on different parts of the
membrane. Numbers of these, yielding a mucous secretion, open into the
mouth and windpipe. They have the appearance of small solid bodies,
often of a flattened lenticular form, but varying much both in shape and
size, and placed at different depths below the mucous membrane on which
their ducts open. The glands of Brunner, which form a dense layer in the
commencing part of the duodenum, are of this kind.
3. Solitary and agminated glands, conglobate glands (Henle), follicular
glands (Kolliker). Found in various parts of the alimentary mucous mem-
brane, also in the palpebral conjunctiva. They may be single (solitary
glands), or in patches (agminated glands). Their structure is well known,
but, although they are called glands, their function is still enigmatical.
They are small sacs reaching down into the submucous tissue, closed and
covered above by the mucous membrane. Within is fine retiform tissue,
supporting radiating blood-capillaries, with bodies like lymph-cor-
puscles in the meshes, and communicating with a similar tissue (lymphoid
tissue) diffused in the adjacent part of the membrane ; for, although they
do not open on the surface, their reticular capsule rarely forms a perfect
inclosure. Several of these saccules are sometimes placed round a recess of
THE SKIX. cci
the mucous membrane which opens on the surface, and which may be
simple, as in certain glands at the root of the tongue and in the pharynx,
or complex and multilocular, as in the tonsils.
On the hypothesis that these bodies are really secreting glands, it has been pre-
sumed that they are occasionally opened by dehiscence for the discharge of their
contents. According to another view they are dependencies of the lymphatic system,
and there are various analogies and indications of relationship which might be
adduced in favour of this opinion. On the other hand, it is not easy to see what
special connection there can be between the lymphatic system and the collections
of these bodies at the root of the tongue and in the tonsils, where, indeed, their
presence is more reconcileable with the notion of their being secreting organs ; in
short, it must be confessed that the question as to their function has still to be
answered.
Nerves. The mucous membranes are supplied with nerves, and endowed
with sensibility ; but the proportion of nerves which they receive, as well
as the degree of sensibility which they possess, differs very greatly in
different parts. As to the mode of distribution and termination of their
nerves, there is nothing to be said beyond what has been already stated in
treating of the nerves in general.
Secretion. Mucus is a more or less viscid, transparent, or slightly turbid fluid, of
variable consistency. It is somewhat heavier than water, though expectorated mucus
is generally prevented from sinking in that liquid by entangled air-bubbles. Examined
with the microscope, it is found to consist of a fluid, containing solid particles of
various kinds, viz., 1. Epithelium-particles detached by desquamation ; 2. Mucus-
corpuscles, which are bodies resembling much the pale corpuscles of the blood ;
3. Granules and molecules occasionally. The viscidity of mucus depends on the
liquid part, which contains a peculiar substance, named by the chemists mucin.
This ingredient is precipitated and the mucus rendered turbid by the addition of
water or a weak acid, but it may be partly redissolved in an excess of water, and
completely so in a strong acid. This mucin is soluble in alkalies, and its acid
solutions are not precipitated by ferrocyanide of potassium. Little can, of course,
be expected from a chemical analysis of a heterogeneous and inseparable mixture of
solid particles with a liquid solution, such as we find in mucus, which is, moreover,
subject to differences of quality according to the part of the mucous membrane whence
it is derived. Examined thus in the gross, however, the nasal mucus has been found
to yield water, mucin, alcohol-extract with alkaline lactates, water-extract with traces
of albumen and a phosphate, chlorides of sodium and potassium, and soda. Fat has
been obtained by analysis of pulmonary mucus, reputed healthy.
Regeneration. The reparatory process is active in the mucous membranes.
Breaches of continuity occasioned by sloughing, ulceration, or other causes, readily
heal. The steps of the process have been examined with most care in the healing of
ulcers of the large intestine, and in such cases it has been found that the resulting
cicatrix becomes covered with epithelium, but that the tubular follicles are not re-
produced.
THE SKIN.
The skin consists of the cutis vera or corium, and the cuticle or epidermis.
The epidermis, cuticle, or scarf-skin, belongs to the class of epithelial struc-
tures, the general nature of which has been already considered. It forms a
protective covering over every part of the true skin, and is itself quite in-
sensible and non-vascular. The thickness of the cuticle varies in different
parts of the surface, measuring in some not more than -g^th, and in others
from ^jth to -j^th of an inch. It is thickest in the palms of the hands and
soles of the feet, where the skin is much exposed to pressure, and it is not
ecu
THE SKIN.
Fig. OVIII.
improbable that this may serve to stimulate the subjacent true skin to a
more active formation of epidermis ; but the difference does not depend
solely on external causes, for it is well marked even in the foetus.
Structure. The cuticle is made up of flattened cells agglutinated together
in many irregular layers. They at first contain nuclei with soft and moist
contents, and, by successive formations beneath them, are gradually pushed
to the free surface, become flattened in their progress into thin irregular scales,
for the most part lose their nuclei, and are at last thrown off by desquamation.
The deepest cells are elongated in figure, and placed perpendicularly on the
surface of the corium (fig. cvm. 6), like
the particles of columnar epithelium ;
they are denticulate at their lower
ends, and fit into corresponding fine
dentictilations of the corium. These
perpendicular cells generally form one,
but in some places two or three strata;
above them are cells of a more rounded
shape, c. As the cells change their
form, they undergo chemical and
physical changes in the nature of their
contents ; for those in the deeper layers
contain a soft, opaque, granular matter,
soluble, as well as their envelope, in
acetic acid, whilst the superficial ones
are transparent, dry, and firm, and are
not affected by that acid. It would
seem as if their contents were converted
into a horny matter, and that a portion
of this substance is employed to cement
them together. These dry hard scales
may be made to reassume their cellular
form, by exposure for a few minutes
to a solution of caustic potash or soda,
and then to water. Under this treat-
ment they are softened by the alkali
and distended by imbibition of water.
The more firm and transparent superficial part of the epidermis, d, may be
separated from the deeper, softer, more opaque, and recently formed part,
which constitutes what is called the Malpighian layer, or rete mucosum, c.
Many of the cells of the cuticle contain pigment, and often give the mem-
brane more or less of a tawny colour, even in the white races of mankind ;
the blackness of the skin in the negro depends entirely on the cuticle. The
pigment is contained principally in the cells of the deep layer or rete muco-
sum, and appears to fade as they approach the surface, but even the superfi-
cial part possesses a certain degree of colour. More special details respecting
the pigment have been already given (page Ixiii).
The under or attached surface of the cuticle is moulded on the adjoining
surface of the corium, and, when separated by maceration or putrefaction,
presents impressions corresponding exactly with the papillary or other emi-
nences, and the furrows or depressions of the true skin ; the more pro-
minent inequalities of the latter are marked also on the outer surface of the
cuticle, but less accurately. Fine tubular prolongations of the cuticle sink
down into the ducts of the sweat-glands, and are often partially drawn out
Fig. CVIII. SKIN OP THE NEGRO, IN
A VERTICAL SECTION, MAGNIFIED 250
DIAMETERS.
a, a, cutaneous papillae ; 5, under-
most and dark-coloured layer of oblong
vertical epidermis-cells ; c, raucous or
Malpighian layer ; d, horny layer.
STRUCTURE OF THE COBIUM. cciii
from their recesses when the cuticle is detached, appearing then like threads
proceeding from its under surface.
Chemical composition. The cuticle consists principally of a substance peculiar
to the epithelial and horny tissues, and named keratin. This horny matter is in-
soluble in water at ordinary temperatures, and insoluble in alcohol. It is soluble in
the caustic alkalies. In composition, it is analogous to the albuminoid principles,
but with a somewhat larger proportion of oxgyen ; like these, it contains sulphur.
Besides keratin, the epidermis yields, on analysis, a small amount of fat, with salts,
and traces of the oxides of iron and manganese. The tissue of the cuticle readily im-
bibes water, by which it is rendered soft, thick, and opaque, but it speedily dries
again, and recovers its usual characters.
The true skin, cutis vera, derma, or corium, is a sentient and vascular
texture. It is covered and defended, as already explained, by the insen-
sible and non-vascular cuticle, and is attached to the parts beneath by a
layer of areolar tissue, named "subcutaneous," which, excepting in a few
parts, contains fat, and has therefore been called also the " panniculus adi-
posus " (rig. cxxin. d.). The connection is in many parts loose and movable,
in others close and firm, as on the palmar surface of the hand and the sole of
the foot, where the skin is fixed to the subjacent fascia by numerous stout
fibrous bauds, the space between being filled with a firm padding of fat. In
some regions of the body the skin is moved by striated muscular fibres,
which may be unconnected to fixed parts, as in the case of the orbicular
muscle of the mouth, or may be attached beneath to bones or fasciae, like
the other cutaneous muscles of the face and neck, and the short palmar
muscle of the hand.
Structure. The corium consists of a fibro-vascular layer, which is sup-
posed to be bounded at the surface next the cuticle, by a fine homogeneous
basement-membrane or membrana propria, like the corresponding part of
the mucous membrane. No such superficial film can, it is true, be raised
from the corium, but, from its distinct presence in small gland-ducts which
are continuous with the corium, and from the fact that a thin homogeneous
membrane lies between the commencing cutis and cuticle in the embryo, it
is presumed that a limitary membrane of this sort ought to be reckoned as
an element of the corium, although, as in the analogous case of the mucous
membrane, it cannot be shown to exist generally over the surface. The
Jibro-vascular part is made up of an exceedingly strong and tough framework
of interlaced fibres, with blood-vessels and lymphatics. The fibres are chiefly
of the white variety, such as constitute the chief part of the fibrous and areolar
tissues, and are arranged in stout interlacing bundles, except at and near
the surface, where the texture of the corium becomes very fine. With these
are mixed yellow or elastic fibres, which vary in amount in different parts,
but in all cases are present in smaller proportion than the former kind ; also
connective tissue corpuscles, fusiform or ramified, and for the most part reticu-
larly anastomosing. The interlacement becomes much closer and finer
towards the free surface of the corium, and there the fibres can be discovered
only by teasing out the tissue, which often acquires an almost homogeneous
aspect. Towards the attached surface, on the other hand, the texture be-
comes much more open, with larger and larger meshes, in which lumps
of fat and the small sudatory glands are lodged ; and thus the fibrous part
of the skin, becoming more and more lax and more mixed with fat, blends
gradually with the subcutaneous areolar tissue to which it is allied in elemen-
tary constitution. Bundles of plain muscular tissue are distributed in the
CC1V
THE SKIN.
substance of the corium wherever hairs occur ; and their connection with
fehe latter will be afterwards explained. Muscular bundles of the same
kind are found in the subcutaneous tissue of the scrotum, penis, perineum,
and areola of the nipple, as well as in the nipple itself. They join to form
reticular superimposed layers, which are separated from the parts beneath
by a stratum of simple lax areolar tissue, but towards the surface they
are immediately applied to the corium. In the areola they are disposed
circularly.
In consequence of this gradual transition of the corium into the subjacent
tissue, its thickness cannot be assigned with perfect precision. It is gene-
rally said to measure from a quarter of a line or less to nearly a line and a
half. -As a general rule, it is thicker on the posterior aspect of the head,
neck, and trunk, than in front ; and thicker on the outer than on the inner
side of the limbs. The corium, as well as the cuticle, is remarkably thick
on the soles of the feet and palms of the hands. The skin of the female is
thinner than that of the male.
For convenience of description it is not unusual to speak of the corium as
consisting of two layers, the " reticular" and the " papillary." The former,
the more deeply seated, takes no part in the construction of the papilla,
but contains in its meshes hair-follicles, cutaneous glands, and fat. The
latter is divided into papillae, and receives only the upper portion of the
hair-follicles and glands, together with the terminal expansion of the vessels
and nerves.
The free surface of the corium is marked in various places with larger or
smaller furrows, which also affect the super] acent cuticle. The larger of
them are seen opposite the flexures of the joints, as those so well known in
the palm of the hand and ut the joints of the fingers. The finer furrows
intersect each other at various angles, and may be seen almost all over the
surface ; they are very conspicuous on the back of the hands. These fur-
rows are not merely the consequence of the frequent folding of the skin by
the action of muscles or the bending of joints, for they exist in the foetus.
The wrinkles of old persons are of a different nature, and are caused
by the wasting of the soft parts which the skin covers. Fine curvili-
near ridges, with intervening furrows, mark the skin of the palm and
sole ; these are caused by ranges of the papillse, to be immediately de-
scribed.
. The free surface of the corium is be^et with small enrnences
Fig. CIX.
Fig. CX.
Fig. CIX. PAPILLA, AS SEEN WITH A MICROSCOPE, ON A PORTION OF THE TRUE SKIN,
FROM WHICH THE ClJTICLE HAS BEEN REMOVED (after Breschet).
Fig. CX. COMPOUND PAPILLA FROM THE PALM OF THE HAND, MAGNIFIED 60 DIAMETERS.
a, basis of a papilla ; 5, b, divisions or branches of the same ; c, c, branches belonging
to papillaa of which the bases are hidden from view (after Kolliker).
PAPILLAE AND VESSELS.
ccv
thus named, which seem chiefly intended to contribute to the perfection of
the skin as an organ of touch, seeing that they are highly developed where
the sense of touch is exquisite, and vice versa. They serve also to extend the
surface for the production of the cuticular tissue, and hence are large-sized
and numerous under the nail. The papillae are large, and in close array on
the palm and palmar surface of the fingers, and on the corresponding parts
of the foot (fig. ex. ). There they are ranged in lines forming the curvilinear
ridges seen when the skin is still covered with its thick epidermis. They are
of a conical figure, rounded or blunt at the top, and sometimes cleft into
two or more points, when they are named compound papillae. They are
received into corresponding pits on the under surface of the cuticle. In
structure they resemble the superficial layer of the corium generally, and
consist of a homogeneous tissue, presenting only faint traces of fibrillation,
together with a few fine elastic fibres. On the palm, sole, and nipple,
where they are mostly of the compound variety, they measure from ^^ ff
to -j^* of an inch in height. In the ridges, the larger papilla} are placed
sometimes in single but more commonly in double rows, with smaller ones
between them (rig. cxxm.), that is, also on the ridges, for there are none in
the intervening grooves. These ridges are marked at short and tolerably
regular intervals with notches, or short transverse furrows, in each of which,
about its middle, is the minute funnel-shaped orifice of the duct of a sweat
gland (fig. cxi.). In other parts of the skin endowed with less sensibility,
the papillae are smaller, shorter, fewer in number, and irregularly scattered.
On the face they are reduced to from -g^ to 3-^ of an inch ; and here
they at parts disappear altogether, or are replaced by slightly elevated reti-
cular ridges. In parts where they are naturally small, they often become
enlarged by chronic inflammation round the margin
of sores and ulcers of long standing, and are
then much more conspicuous. Fine blood-
vessels enter most of the papillae, forming either
simple capillary loops in each, or dividing into two
or more capillary branches, according to the size
of the papilla and its simple or composite form,
which turn round in form of loops and return to
the veins. Other papillae receive nerves, to be
presently noticed.
Blood-vessels and lymphatics. The blood-vessels
divide into branches in the subcutaneous tissue,
and, as they enter the skin, supply capillary plex-
uses to the fat-clusters, sweat-glands, and hair-
follicles. They divide and anastomose still further
as they approach the surface, and at length, on
reaching it, form a dense network of capillaries,
with rounded polygonal meshes. Fine branches are
sent into the papillie, as already mentioned. The
lymphatics are abundant in some parts of the skin,
as on the scrotum and round the nipple ; whether
they are equally so in all parts may be doubted.
They form networks, which become finer as they
approach the surface, and communicate underneath
with straight vessels, and these, after a longer or a
shorter course, join larger ones or enter lymphatic glands. The finest and
most superficial network, although close to the surface of the corium, is
Fig. CXI.
g. CXI. MAGNIFIED
VlKW OF FOUR OF THE
RIDGES OF THE EPIDER-
MIS, CAUSED BY ROWS OF
PAPILLAE BENEATH, WITH
SHORT FURROWS OR
NOTCHES ACROSS THEM ;
ALSO THE OPENINGS
OF THE SUDORIFEROUS
DUCTS (after Brescia et).
ccvi THE SKIK
beneath the net of superficial blood-capillaries ; in certain parts on the
palm and sole, lymphatics pass into the papillae, but do not reach their
summits.
Nerves. Nerves are supplied in very different proportions to different
regions of the skin, and according to the degree of sensibility. They pa?s
upwards towards the papillary surface, where they form plexuses, of which
the meshes become closer as they approach the surface, and the constituent
branches finer, so that the latter come at last to consist of only one or two
primitive fibres. The fibres also become more attenuated the further they
proceed towards their final destination. In the finest and most superficial
part of the plexus, the ultimate fibres, or at least some of them, undergo
actual division. Little more can be said of the termination of nerves on the
general cutaneous surface. A large share of the cutaneous nerves is dis-
tributed to the hair- follicles, whilst some end in special terminal organs,
namely, end-bulbs, tactile corpuscles, and Pacinian bodies. The last named
bodies are seated in the subcutaneous tissue. End-bulbs are found on the
glans penis and glaus clitoridis, and in some of the papillse on the red
border of the lips. The tactile corpuscles of the skin are more numerous ;
they are found in certain papilla of the palm and sole, more sparingly in
those of the back of the hand and foot, the palmar surface of the fore-arm
and the nipple. Such papillse commonly contain no blood-vessels, and are
named "tactile," as distinguished from the "vascular" papillse which
receive no nerves. Sometimes, however, a tactile and a vascular papilla
may spring from the same stem. The structure of these different terminal
corpuscles has been already described (pages cl to civ).
Chemical composition. The corium being composed chiefly of white fibrous tissue,
has a corresponding chemical composition. It is, accordingly, in a great measure,
resolved into gelatin by boiling, and hence, also, its conversion into leather by the
tanning process.
Development of the cutis. The cutis consists at first of cells which may in animals
be traced back to the first formative cells of the embryo. Many of them give rise to
connective tissue ; others to vessels and nerves ; and a third portion is converted into
fat-cells. No doubt the muscular tissue also originates from cells. The mode of
formation of these several elementary tissues has been already described. Progressive
development takes place from within outwards, so that the papillae are formed
latest.
The cuticle at first differs in no point from the cutis, but consists of the earliest
formative cells. Their subsequent metamorphoses and the mode of production of new
cells have not been accurately determined ; the question has been already considered
at page Iv.
Nails and hairs. The nails and hairs are growths of the epidermis,
agreeing essentially in nature with that membrane ; their epidermic tissue
is destitute of vessels and nerves, and separable from the cutis.
Nails. The posterior part of the nail which is concealed in a groove of
the skin is named its "root," the uncovered part is the "body," which
terminates in front by the "free edge." A small portion of the nail near
the root, named from its shape the lunula, is whiter than the rest. This
appearance is due partly to some degree of opacity of the substance of the
nail at this point, and partly to the skin beneath being less vascular than
in front.
The part of the coriurn to which the nail is attached, and by which in
fact it is secreted or generated, is named the matrix. This portion of the
skin is highly vascular and thickly covered with large vascular papillse.
NAILS;
ccvii
Posteriorly the matrix forms a crescentic groove or fold, deep in the
middle but getting shallower at the sides, which lodges the root of the
nail ; the rest of the matrix, before the groove, is usually named the bed of
the nail. The small lighter-coloured part of the matrix next the groove
and corresponding with the lunula of the nail, is covered with papillae
having no regular arrangement, but the whole remaining surface of the
matrix situated in front of this, and supporting the body of the nail, is
marked with longitudinal and very slightly diverging ridges cleft at their
summits into rows of papillae. These ridges, or lamina, as they are some-
times, and perhaps more suitably, named, fit into corresponding furrows on
the under surface of the nail. The cuticle, advancing from the back of the
finger, becomes attached to the upper surface of the nail near its posterior
edge, that is, all round the margin of the groove in which the nail is
lodged ; in front the cuticle of the point of the finger becomes continuous
with the under surface of the nail a little way behind its free edge.
The nail, like the cuticle, is made up of scales derived from flattened
cells. The oldest and most superficial of these are the broadest and
hardest, but at the same time very thin and irregular, and so intimately
and confusedly connected together that their respective limits are scarcely
discernible. They form the
exterior, horny part of the Fig. CXII.
nail, and cohere together in
irregular layers, so as to
give this part a lamellar
structure. On the other
hand, the youngest cells,
which are those situated at
the root and under surface,
are softer and of a rounded
or polygonal shape. The
deepest layer differs some-
what from the others, in
having its cells elongated,
and arranged perpendicular-
ly, as in the case of the
epidermis. Thus the under
part of the nail (fig. cxn. B)
corresponds in nature with
the Malpighian or mucous
layer of the epidermis, and
the upper part (c) with the
horny layer. As in the
case of the epidermis, the
hardened scales may be made
to reassume their cellular
character by treatment with
caustic alkali, and after-
wards with water ; and
then it is seen that they
still retain their nuclei. In chemical composition the nails resemble epider-
mis ; but, according to Mulder, they contain a somewhat larger proportion
of carbon and sulphur.
The growth of the nail is effected by a constant generation of cells at the
Fig. CXII. VERTICAL TRANSVERSE SECTION THROUGH
A SMALL PORTION OF THE NAIL AND MATRIX,
LARGELY MAGNIFIED (after Kolliker).
A, corium of the nail-bed, raised into ridges or
laminae, a, fitting in between corresponding laminae, b,
of the nail; B, Malpighian, and C, horny layer; d,
deepest and vertical cells ; e, upper flattened cells of
Malpighian layer.
ccviii HAIRS.
root and under surface. Each successive series of these cells being followed
and pushed from their original place by others, become flattened into
dry, hard, and inseparably coherent scales. By the addition of new cells
at the posterior edge the nail is made to advance, and by the apposition of
similar particles to its under surface it grows in thickness ; so that it is
thicker at the free border than at the root. The nail being thus merely an
exuberant part of the epidermis, the question at one time raised, whether
that membrane is continued underneath it, loses its significance. When a
nail is thrown off by suppuration, or pulled away by violence, a new one is
produced in its place, provided the matrix remains.
Development in the foetus. In the third month of intra-uterine life the part
of the embryonic corium which becomes the matrix of the nail is marked off by the
commencing curvilinear groove, which limits it posteriorly and laterally. The
epidermis on the matrix then begins to assume, in its under part, the characters of a
nail, which might, therefore, be said to be at first covered over by the embryonic
cuticle. After the end of the fifth month it becomes free at the anterior border, and
in the seventh month decidedly begins and thenceforth continues to grow in length.
At birth the free end is long and thin, being manifestly the earlier formed part which
has been pushed forward. This breaks or is pared off after birth, and, as the
infantile nail continues to grow, its flattened cells, at first easily separable, become
harder and more coherent, as in after life.
Hairs. A hair consists of the root, which is fixed in the skin, the shaft
or stem, and the point. The stem is generally cylindrical, but often more
or less flattened ; sometimes it is grooved along one side, and therefore
reniform in a cross section : when the hair is entire, it becomes gradually
smaller towards the point. The length and thickness vary greatly in
different individuals and races of mankind as well as in different regions of
the body. Light-coloured hair is usually finer than black.
Fig. CXIII.
Fig. CXIII. A, SURFACE OP A WHITE HAIR, MAGNIFIED 160 DIAMETERS. THE WAVED
LINES MARK THE UPPER OR FREE EDGES OF THE CORTICAL SCALES. B, SEPARATED
SCALES, MAGNIFIED 350 DIAMETERS (after Kolliker).
The stem is covered with a coating of finely imbricated scales, the
upwardly projecting serrated edges of which give rise to a series of fine
waved transverse lines, which may be seen with the microscope on the
surface of the hair (fig. cxm. A). Within this scaly covering, by some
called the hair-cuticle, is a fibrous substance which in all cases constitutes
the chief part and often the whole of the stem ; but in many hairs the axis
is occupied by a substance of a different nature, called the medulla or pith,
for which reason the surrounding fibrous part is often named " cortical,"
STRUCTURE OF HAIRS. ccix
although this term is more properly applied to the superficial coating of
scales above mentioned. The fibrous substance is translucent, with short
longitudinal opaque streaks of darker colour intermixed. It may be
broken up into straight, rigid, longitudinal fibres, which, when separated,
are found to be flattened, broad in the middle, where they measure 4^-5-
of an inch in breadth, and pointed at each end, with dark and rough edges.
The fibres may be resolved into flattened cells of a fusiform outline ; these
are mostly transparent, or marked with only a few dark specks. The
colour of the fibrous substance is caused by oblong patches of pigment-
granules, and generally diffused colouring matter of less intensity. Very
slender elongated nuclei are also discovered by means of reagents, whilst
specks or marks of another description in the fibrous substance are
occasioned by minute irregularly shaped cavities containing air. These
air-lacunules are abundant in white hairs, and in very dark hairs may be
altogether wanting ; they are best seen too in the former, in which there is
no risk of deception from pigment-specks. Viewed by transmitted light
they are dark, but brilliantly white by reflected light. When a white hair
has been boiled in water, ether, or oil of turpentine, these cavities become
filled with fluid, and are then quite pellucid ; but when a hair which has
been thus treated is dried, the air quickly finds its way again into the
lacunae, and they resume their original aspect.
The medulla or pith, as already remarked, does not exist in all hairs.
It is wanting in the fine hairs over the general surface of the body, and is
not commonly met with in those of the head ; nor in the hairs of children
under five years. When present it occupies the centre of the shaft and
ceases towards the point. It is more opaque and deep-coloured than the
fibrous part ; in the white hairs of quadrupeds it is white, but opaque and
dark when seen by transmitted light. It seems to be composed of little
clusters of cells, differing in shape, but generally angular, and containing
minute particles, some resembling pigment-granules, and others like very
fine fat-granules, but really for the most part air-particles, apparently
included in some solidified tenaceous substance. The whole forms a con-
tinuous dark mass along the middle of the stem, interrupted at parts for a
greater or less extent. In the latter case, the axis of the stem at the inter-
ruptions may be fibrous like the surrounding parts, or these intervals may
be occupied by a clear colourless matter ; and, according to Henle, some
hairs present the appearance of a sort of canal running along the axis and
filled in certain parts with opaque granular matter, and in others with a
homogeneous transparent substance.
The root of the hair is lighter in colour and softer than the stem ; it
swells out at its lower end into a bulbous enlargement or knob (fig.
cxiv. c), and is received into a recess of the skin named the hair-follicle,
which, when the hair is of considerable size, reaches down into the subcu-
taneous fat. The follicle, which receives near its mouth the opening ducts
of one or more sebaceous glands (k, fc), is somewhat dilated at the bottom,
to correspond with the bulging of the root ; it consists of an outer coat
continuous with the corium (fig. cxiv. g, h ; cxv. d, d), and an epidermic
lining (fig. cxiv. e, f ; cxv. 6, c), continuous with the cuticle. The outer
or dermic coat is thin but firm, and consists of three layers. The most
external is formed of connective tissue in longitudinal bundles, without
any elastic fibres, but with numerous long fusiform corpuscles. It is
highly vascular, and possesses nervous fibrils. It is intimately connected
above with the corium, and determines the form of the follicle. The most
ccx
HAIRS.
internal layer (hyaline coat, Kolliker) is a transparent homogeneous mem-
brane, marked transversely on its inner surface with some raised lines, and
not reaching so high as the mouth of the follicle ; it corresponds with the
Fig. CXIV.
Fig. CXV.
Fig. CXIV. MEDIUM-SIZED HAIR
IN ITS FOLLICLE, MAGNIFIED
50 DIAMETERS (from Kolliker).
a, stem cut short ; &, root ; c,
knob ; d, hair cuticle ; e, internal,
and /, external root-sheath ; g, h,
dermic coat of follicle ; i, papilla ;
Jc k, ducts of sebaceous glands ; I,
corium ; m, mucous layer, and n,
horny layer of epidermis ; o, upper
limit of internal root-sbeath (from
Kolliker).
Fig. CXV. MAGNIFIED VIEW OF THE ROOT OF
A HAIR (after Koblrauscb).
a, stem or sbaffc of hair cut across ; &, inner,
and c, outer layer of tbe epidermic lining of the
hair-follicle, called also the inner and outer root-
sheath ; d, dermic or external coat of the hair-
follicle, shown in part ; e, imbricated scales about
to form a cortical layer on the surface of the hair.
The adjacent cuticle of the root-sheath is not repre-
sented, and the papilla is hidden in the lower
part of the knob where that is represented lighter.
membrana propria or basement membrane
of analogous structures. Between the two
is a layer extending from the bottom of
the follicle as high as the entrance of the
sebaceous glands, composed of an indis-
tinctly fibrous matrix, tearing transversely,
and of transversely disposed fusiform
connective tissue corpuscles, with oblong
nuclei. This layer, which seems to be a
form of connective tissue, receives capillary blood-vessels, but without as
yet recognized nerves. The epidermic lining adheres closely to the root
of the hair, and commonly separates, in great part, from the follicle and
abides by the hair when the latter is pulled out ; hence it is sometimes
named the " root-sheath." It consists of an outer, softer, and more opaque
stratum (fig. cxv. , c, c) next the dermic coat of the follicle, and an internal
more transparent layer (6, b) next the hair. The former, named also the
outer root-sheath, and by much the thicker of the two, corresponds with the
HAIR-FOLLICLES. ccxi
mucous or Malpigliian layer of the epidermis in general, and contains soft
growing cells, including pigment in the coloured races, which at the lower
part form a much thinner stratum and pass continuously into those of the
hair-knob ; the internal layer or inner root-sheath represents the superficial
or horny layer of the epidermis according to some authorities ; but others
maintain that it is not continuous with that part of the skin, but ceases
abruptly a little below the orifices of the sebaceous ducts. When detached
from the hair it is found to be covered internally with imbricated down-
wardly projecting scales, forming the cuticle of the root-sheath, which is
applied to the cortical scaly cuticle of the hair proper, to whose upwardly
directed scales it fits like a mould. Its scales, as well as those of the
hair-cuticle, pass, at the bottom of the follicle, into the round cells of the
hair-knob. Now, after reckoning off this cuticular lining, the inner root-
sheath still consists of two layers, which towards the bottom of the follicle
become blended into one. The innermost (that next the cuticula) is known
as Huxley's layer ; it consists of flattened polygonal nucleated cells, two or
even three deep. The outer layer is composed of oblong, somewhat flat-
tened cells without nuclei, in which fissures and holes are liable to occur
from accidental laceration, so as to give it the aspect of a perforated or
fenestrated membrane. At the lower part both layers pass into a single
layer of large polygonal nucleated cells without openings between them.
The soft bulbous enlargement of the root of the hair is attached by its
base to the bottom of the follicle, and at the circumference of this attached
part it is continuous with the epidermic lining. At the bottom of the follicle
it, in fact, takes the place of the epidermis, of which it is a growth or
extension, and this part of the follicle is the true matrix of the hair, being,
in reality, a part of the corium (though sunk below the general surface),
which supplies material for the production of the hair. This productive
part of the follicle is, accordingly, remarkably vascular ; in the large
tactile hairs on the snout of the seal and some other animals it is raised in
form of a conical vascular papilla or pulp, which fits into a corresponding
excavation of the hair-root ; and Kolliker states that a vascular eminence of
similar structure exists in the hairs generally, both small and large, of man
as well as quadrupeds. As the follicle, in short, is a recess of the corium,
so the hair-papilla is a cutaneous papilla sunk in the bottom of it. The
papilla is described as being commonly of an ovoid shape and attached to
the bottom of the follicle by a narrow base, or a sort of pedicle (fig. cxiv., i).
Nervous branches of considerable size enter the follicles of the large tactile
hairs referred to, but their final distribution has not been traced ; the pain
occasioned by pulling the hair seems to indicate that the human hair-
follicles are not unprovided with nerves.
Fine muscles, each formed of a slender bundle of plain muscular tissue,
are connected with the hair-follicles (fig. cxvi.). Their mode of attachment
is described by Kolliker and Lister to be the following : they arise from,
the most superficial part of the corium, and pass down obliquely to be
inserted into the outside of the follicle below the sebaceous glands. They
are placed on the side to which the hair slopes, so that their action in
elevating the hair is evident. Some anatomists have also recently described
a layer of circularly disposed muscular cells as applied immediately to the
outside of the follicle.
Growth of hair. On the surface of the papilla or vascular matrix, at the
bottom of the follicle, there is a growth of nucleated cells. The cells for the
most part lengthen out and unite into the flattened fibres which compose
ccxii HAIRS.
the fibrous part of the hair, and certain of them, previously getting filled
with pigment, give rise to the coloured streaks and patches in that tissue ;
their nuclei, at first, also lengthen in the same manner, but, at last, partly
become indistinct. The cells next the circumference expand into the scales
which form the imbricated cuticular layer (fig. cxv., e, e). The medulla,
where it exists, is formed by the cells nearest the centre ; these retain their
primitive figure longer than the rest ; they become coherent, and their
cavities may coalesce together by destruction of their mutually adherent
parietes, whilst collections of pigment granules make their appearance in
them and around their nuclei, forming an opaque mass, which occupies the
axis of the hair.
Fig. CXVII.
Fig. CXVL SECTION OF THE SKIN OF THE HEAT>, WITH TWO HAIR FOLLICLES,
SLIGHTLY MAGNIFIED (from Kblliker).
a, epidermis ; b, corium ; c, muscles of the hair-follicles.
Fig. CXVII. HAIR RUDIMENT FROM AN EMBRYO OF Six WEEKS, MAGNIFIED 350
DIAMETERS (after Kolliker).
a, horny, and 6, mucous or Malpigbian layer of cuticle ; i, 1'mitary membrane ; m, cells
some of which are assuming an oblong figure, which chiefly form the future hair.
The substance of the hair, of epidermic nature, is, like the epidermis
itself, quite extravascular, but, like that structure also, it is organised and
subject to internal organic changes. Thus, in the progress of its growth,
the cells change their figure, and acquire greater consistency. In conse-
quence of their elongation, the hair, bulbous at the commencement, becomes
reduced in diameter and cylindrical above. But it cannot be said to what
precise distance from the root organic changes may extend. Some have
imagined that the hairs are slowly permeated by a fluid, from the root to
the point, but this has not been proved. The sudden change of the colour
of the hair from dark to grey, which sometimes happens, has never been
satisfactorily explained.
Development of the hair in the foetus. The rudiments of the hairs may be dis-
cerned at the end of the third or beginning of the fourth month of intra-uterine life,
as little black specks beneath the cuticle. They at first appear as little pits in the
corium (fig. cxvu.), filled with cells of precisely the same nature as those of the
Malpighian or mucous layer of the cuticle, with which they are continuous; so it
might correctly be said that the hair-rudiments are formed of down growths of
the mucous layer, which sink into the corium. A homogeneous limiting membrane
next appears (?'), inclosing the collection of cells, and continuous above with a similar
simple film which at this time lies between the cuticle and the corium; it becomes
the innermost or hyaline layer of the dermic coat of the follicle. The hair-rudiments
next lengthen and swell out at the bottom, so as to assume a flask -shape (fig. cxvin.).
DEVELOPMENT OF HAIRS.
Cells are deposited outside the limitary membrane, which eventually give rise to
fibres, corpuscles, and other constituents of the dermic coat. While this is going on
outside, the cells within the follicle undergo changes. Those in the middle lengthen
out conformably with the axis of the follicle, and give rise to the appearance of a
short conical miniature hair, faintly distinguishable by difference of shade from the
surrounding mass of cells, which are also slightly elongated, but across the direction
of the follicle. The papilla (figs, cxviu., &c., h) makes its appearance at the swollen
root of the little hair ; and the residuary cells contained within the rudimentary
follicle form the root-sheath, the inner layer of which, or inner root-sheath, lying
next to the hair (fig. cxix., d), is soon distinguished by its translucency from the more
opaque outer part that fills up the rest of the cavity. The young hair continuing to
grow, at last perforates the cuticle (fig. cxx., g), either directly, or after first slanting
up for some way between the mucous and horny strata. The young hair is often bent
like a whip, and then the double part protrudes.
Fig. CXVIII.
Fig. CXIX.
Fig. CXVIII. RUDIMENT OF A HAIR OF THE EYEBROW, MAGNIFIED 50 DIAMETERS
(after Kolliker).
The cells form an internal cone indicating the position of the future ^ hair, a, horny
layer of cuticle ; 6, mucous layer ; c, external layer of root-sheath ; i, limitary membrane ;
~h, papilla.
Fig. CXIX. HAIR-RUDIMENT MEASURING 0'22 OF A LINE, FROM THE EYEBROW, WITH
THE YOUNG HAIR NOT YET RISEN THROUGH THE CUTICLE (after Kolliker).
a, 6, c, h, i, as in fig. cxviu. ; e, hair-knob ; /, stem, and g t point of the hair ; d,
internal layer of the root-sheatb, still inclosing the hair ; n, n, commencing sebaceous
follicles.
Fig. CXX. HAIR-FOLLICLE FROM THE EYEBROW WITH THE HAIR JUST ERUPTED ; THE
INNER LAYER OF THE ROOT-SHEATH RISES TO THE MOUTH OF THE HAIR-FOLLICLE
(after Kolliker.)
The letters denote the same parts as in Fig. CXIX.
The first hairs produced constitute the lanurjo ; their eruption takes place about
the fifth month of intra-uterine life, but part of them are shed before birth, and are
found floating in the liquor amnii. Kolliker affirms that the infantile hairs are
entirely shed and renewed within a few months after birth ; those of the general sur-
P
HAIRS.
face first, and afterwards the hairs of the eyelashes and head, which he finds in process
of change in infants about a year old.
The new hairs are generated in the follicles of the old (figs, cxxi., and oxxn.). An
increased growth of cells takes place in the soft hair-knob, and in the adjoining part
of the root-sheath (the outer layer) : the growing mass pushes up the hair-knob, and
detaches it from its generative papilla. The newly formed mass of cells, occupying the
lower part of the follicle, and resting on the papilla, is gradually converted into a new
hair with its root-sheath, just as in the primitive process of formation in the embryo ;
and as the new hair lengthens and emerges from the follicle, the old one, separated
from its matrix by the interposition of the new growth, is gradually pushed towards
the opening, and at last falls out, its root-sheath having previously undergone
partial absorption. When a hair is pulled out, a new one grows in its place, provided
the follicle (from which the growth proceeds) remains entire. Heusinger, who expe-
rimentally studied the process in the large hairs situated on the lips of the dog, found
that a new hair appeared above the surface in a few days after the evulsion of the old
one, and attained its full size in about three weeks.
Fig. CXXI.
Fig. CXXII.
Fig. CXXI. Two EYELASHES OF AN INFANT, PULLED OUT FROM THEIR FOLLICLES,
MAGNIFIED 20 DIAMETERS (from Kolllker).
A, the new cell-growth forming a cone, m, in the interior (as in fig. CXVIH.). In B, the
cone has separated into the new hair, /, g, and its inner root-sheath, b; a, outer,
and b, inner root-sheath of new hair ; c, pit for papilla ; d and e, the knob and stem of
old hair ; /, knob ; g, stem ; and A, the point of new hair ; i, sebaceous glands ; &, k,
sweat-glands here opening into mouth of hair-follicle.
Fig. CXXII. EYELASH OF AN INFANT, WITH YOUNG HAIR COME FORTH, MAGNIFIED 20
DIAMETERS (from Kolliker).
I, epidermis continuous with outer root-sheath ; other letters as in preceding figures.
Distribution and arrangement. Hairs are found on all parts of the skin except the
palms of the hands and soles of the feet, the dorsal surface of the third phalanges of
the fingers and toes, the upper eyelids, the glans, and the inner surface of the prepuce.
CUTANEOUS GLANDS.
On the head they are set in groups, on the rest of the skin for the most part singly.
Except those of the eyelashes, which are implanted perpendicularly to the surface,
they have usually a slanting direction, which is wonderfully constant in the same
parts.
Chemical nature. The chemical composition of hair has been investigated princi-
pally by Vauquelin, Scherer, and Van Laer. When treated with boiling alcohol, and
with ether, it yields a certain amount of oily fat, consisting of margarin, margaric
acid, and olein, which is red or dark coloured, according to the tint of the hair. The
animal matter of the hair thus freed from fat, is supposed to consist of a substance
yielding gelatine, and a protein compound containing a large proportion of sulphur.
It is insoluble in water, .unless by long boiling under pressure, by which it is reduced
into a viscid mass. It readily and completely dissolves in caustic alkalies. By calci-
nation, hair yields from 1 to 1^ per cent, of ashes, which consist of the following ingre-
dients viz., peroxide of iron, and according to Vauquelin, traces of manganese, silica,
chlorides of sodium and potassium, sulphates of lime and magnesia, and phosphate of
lime. With the exception of the bones and teeth, no tissue of the body withstands
decay after death so long as the hair, and hence it is often found preserved in
sepulchres, when nothing else remains but the skeleton.
Glands of the skin. These are of two kiiids, the sweat-glands, and the
sebaceous, which yield a fatty secretion.
Fig. CXXIII.
Fig. CXXIV.
,-cf
Fig. CXXIII. VERTICAL SECTION OP THE SKIN AND SUBCUTANEOUS TISSUE, FROM END
OP THE THUMB, ACROSS THE RIDGES AND FURROWS, MAGNIFIED 20 DIAMETERS (from
Kolliker).
a, horny, and 6, mucous layer of the epidermis ; c, corium ; d, panniculus adiposus ;
c, papillae on the ridges ; /, fat-clusters ; </, sweat-glands ; 7t, sweat-ducts ; i, their
openings on the surface.
Fig. CXXIV. MAGNIFIED VIEW OP A SWEAT-GLAND, WITH ITS DUCT (after Wagner).
a, the gland surrounded by vesicles of adipose tissue ; 6, the duct passing through the
corium ; c, its continuation through the lower, and d } through the upper part of the
epidermis.
p 2
ccxvi SWEAT GLANDS.
The sudoriferous glands or sweat-glands (figs. cxxm. and cxxiv.). These
are seated on the under surface of the coriura. and at variable depths in the
subcutaneous adipose tissue. They have the appearance of small round
reddish bodies, each of which, when examined with the microscope, is found
to consist of a fine tube, coiled up into a ball (though sometimes forming
an irregular or flattened figure), from which the tube is continued, as the
duct of the gland, upwards through the true skin and cuticle, and opens on
the surface by a slightly widened orifice. The duct, as it passes through
the epidermis, is twisted like a corkscrew, that is, in parts where the epi-
dermis is sufficiently thick to give room for this ; lower down it is but
slightly curved. Sometimes the duct is formed of two coiled up branches
which join at a short distance from the gland, as happens to be the case
in the specimen represented in figure cxxiv. The tube, both in the gland
and where it forms the excretory duct, consists of an outer coat, continuous
with the corium, and reaching no higher than the surface of the true skin,
a thin homogeneous membrana propria, and an epithelial lining, consisting
of one or more strata of cells (often containing brownish pigment), and con-
tinuous with the epidermis, which alone forms the twisted part of the duct.
The outer, dermic or fibrous, coat is formed of homogeneous or finely
fibrous connective tissue with corpuscles. The larger gland-ducts in. the
axilla, at the root of the penis, on the labia majora, and in the neighbour-
hood of the anus, contain between their coats a layer of non-striated mus-
cular fibres arranged longitudinally. In the larger glands, moreover, the
duct is rarely simple, being more usually parted by repeated dichotomous
division into several branches, which before ending give off short csecal
processes ; in rare cases the branches anastomose. On carefully detaching
the cuticle from the true skin, after its connection has been loosened by
putrefaction, it usually happens that the cuticular linings of the sweat-ducts
get separated from their interior to a certain depth, and are drawn out in
form of short threads attached to the under surface of the epidermis. The
coils of the duct are loosely held together by connective tissue, which may
form a sort of capsule round the body of the gland. Each little sweat-gland
is supplied with a dense cluster of capillary blood-vessels.
The contents of the smaller sweat-glands are fluid, without any formed elements ; but
in the larger sweat-glands of the axilla the contents are semi-fluid, and abound in fine
pale granules and nuclei ; or their secretion is extremely viscid, with a varying quan-
tity of large, opaque, colourless, or yellow granules, with nuclei and cells, similar to
epithelium-cells ; and in both cases it may also contain fat. Kb'lliker states that from
the nature of their contents these larger glands might be separated into a distinct
group from the ordinary sweat-glands, were it not for the presence of transitional forms.
Distribution. Sweat-glands exist in all regions of the skin, and attempts have been
made to determine their relative amount in different parts, for they are not equally
abundant everywhere ; but, while it is easy to count their numbers in a given space on
the palm and sole, the numerical proportion assigned to them in most other regions must
be taken with considerable allowance. According to Krause, nearly 2,800 open on a
square inch of the palm of the hand, and somewhat fewer on an equal extent of the sole
of the foot. He assigns rather more than half this number to a square inch on the back
of the hand, and not quite so many to an equal portion of surface on the forehead, and
the front and sides of the neck ; then come the breast, abdomen, and fore-arm, where
he reckons about 1100 to the inch, and lastly, the lower limbs and the back part of
the neck and trunk, on which the number in the same space is not more than from
400 to 600.
The size of the sweat-glands also varies. According to the observer last named,
the average diameter of the round-shaped ones is about one-sixth of a line; but in
some parts they are larger than this as, for example, in the groin, but especially in
SEBACEOUS GLANDS.
Fig. CXXV.
the axilla. In this last situation, Krause found the greater number to measure from
one-third of a line to a line, and some nearly two lines in diameter.
The development of the sweat-glands has been carefully studied by Kolliker. He
states that their rudiments, when first discoverable in the embryo, have much the
same appearance as those of the hairs, and, in like manner, consist of processes of the
mucous layer of the epidermis, which pass down and are received into corresponding
recesses of the corium. They are formed throughout of cells collected into a solid mass
of an elongated pyriform, or rather club shape, continuous by its small end with the
soft layer of the cuticle, and elsewhere surrounded by a homogeneous limiting mem-
brane, which is prolonged above between the corium and cuticle. The subsequent
changes consist in the elongation of the rudimentary gland, the formation of a
cavity along its axis at first without an outlet-
the prolongation of its canal through the epidermis
to open on the surface, and, in the mean time, the
coiling up of the gradually lengthening gland-tube
into a compact ball, and the twisting of the excre-
tory duct as it proceeds to the orifice. The origi-
nal homogeneous membrane of the duct becomes
thickened and is continuous with the surface of
the corium, whilst an epithelium appears within,
consisting of several layers of polygonal or rounded
cells. The ceruminous glands in the auditory
passage are known to consist of a tube coiled into
a rounded or oval ball, like the sweat-glands ; and
the investigations of Professor Kolliker show such
a further correspondence between the two, in
structure and mode of development, as to lead him
to regard the ceruminous glands as a mere local
variety of the sudoriferous, which, as above noticed,
present specialities both of structure and secretion
in particular regions of the body.
The sebaceous glands (fig. cxxv.), pour out
their secretion at the roots of the hairs, for,
with very few exceptions, they open into
the hair-follicles, and are found wherever
there are hairs. Each has a small duct, which
opens at a short distance within the mouth,
of the hair-follicle, and by its other end,
leads to a cluster of small rounded secreting
saccules, which as well as the duct, are lined
by epithelium, and usually charged with the
fatty secretion, mixed with detached epi-
thelium-particles. The number of saccular
recesses connected with the duct usually
varies from four or five to twenty ; it may
be reduced to two or three, in very small
glands, or even to one, but this is rare.
These glands are lodged in the substance of
the corium. Several may open into the same
hair-follicle, surrounding it on all sides, and
their size is not regulated by the magnitude
Fig. CXXV. SEBACEOUS GLAND
PROM THE FACE WITH BRANCHED
DUCT, OPENING INTO A HAIR-
FOLLICLE, MAGNIFIED 50 DIA-
METERS (from Kolliker).
a, epithelium continuous with
6, the mucous layer of epidermis ;
c, contents of gland ; cZ, d, the
groups of saccules on the branches
of the duct ; e, hair-follicle ; /,
hair.
of the hair. Thus, some of the largest are
connected with the fine downy hairs on the aloe of the nose and other parts
of the face, and there they often become unduly charged with pent-up
secretion. ""'
* A few years ago it was discovered by Dr. Gustavus Simon, that the sebaceous and
ccxviii SKIN.
Development of the sebaceous glands. The rudiments of the sebaceous glands
sprout like little buds from the sides of the hair-follicles; they are at first, in fact,
excrescences of the external or mucous layer of the root-sheath (fig. cxix., n, n), and
are composed entirely of nucleated cells. Each little process soon assumes a flask
shape and is at first solid ; but in due time a group of cells containing fat particles
appears in its centre, and gradually extends itself along the axis of the pedicle
until it penetrates through the root-sheath, and the fat-cells thus escape into the
cavity of the hair-follicle, and constitute the first secretion of the sebaceous gland.
They are soon succeeded by others of the same kind, and the little gland is estab-
lished in its office. Additional saccules and recesses, by which the originally simple
cavity of the gland is complicated, are formed by budding out of its epithelium, as
the first was produced from the epithelial root-sheath, and are excavated in a similar
manner.
It would thus appear that the rudiments of the hair-follicles, sweat-glands, and
sebaceous glands, are all derived from the same source. They all originally appear
as solid bud-like excrescences of the soft Malpighian or mucous layer of the epidermis,
for the outer stratum of the root-sheath must be regarded as such ; these grow down
into the corium, in which recesses are formed to receive them, and which, of course,
yields the material required both for the production of new cells for their further
growth and for the maintenance of their secreting function.
Functions and vital properties of the skin. The skin forms a general external
tegument to the body, defining the surface, and coming into relation with foreign
matters externally, as the mucous membrane, with which it is continuous and in
many respects analogous, does internally. It is also a vast emunctory, by which a
large amount of fluid is eliminated from the system, in this also resembling certain
parts of the mucous membrane Under certain conditions, moreover, it performs the
office of an absorbing surface, but this function is greatly restricted by the epidermis.
Throughout its whole extent the skin is endowed with tactile sensibility, but in very
different degrees in different parts. On the skin of the palm and fingers, which is
largely supplied with nerves and furnished with numerous prominent papillae, the
sense attains a high degree of acuteness ; and this endowment, together with other
conformable arrangements and adaptations, invests the human hand with the cha-
racter of a special organ of touch. A certain though low degree of vital contractility,
depending doubtless on the muscular fibres in its tissue, also belongs to the skin.
This shows itself in the general shrinking of the skin caused by naked exposure to
cold and by certain mental emotions, and producing the state of the surface named
" cutis anseriua," in which the muscular bundles protrude the hair-follicles with which
they are connected, whilst they retract or depress the intermediate cutaneous tissue ;
and this condition of the skin may be produced locally by the electric stimulus applied
by means of the magneto-electric apparatus. The scrotum, as is well known, becomes
shrunk and corrugated by the application of cold or mechanical irritation to its sur-
face ; but in this case the contraction takes place in the subcutaneous tissue and the
skin is puckered.
Reproduction of skin. When a considerable portion of the skin is lost, the breach
is repaired partly by a drawing inwards of the adjoining skin, and partly by the for-
mation of a dense tissue, less vascular than the natural corium, and in which, so far
as I know, hairs and glands are not reproduced, so that some deny that the cutaneous
tissue is regenerated. Still the new part becomes covered with epidermis, and its
substance sufficiently resembles that of the corium to warrant its being considered as
cutaneous tissue regenerated in a simple form. I may add that, in small breaches of
continuity from cuts inflicted in early life, the uniting part sometimes acquires fur-
rows similar to those of the adjoining surface.
SECRETING GLANDS.
The term gland has been applied to various objects, differing widely from
hair follicles were infested by a worm, which he has described and delineated in Mullet's
Archiv for 1842. Since then, further interesting details respecting this curious parasite,
with observations on its development, have been contributed by Mr. E. Wilson. Phil.
Trans. 1344.
SECRETING GLANDS. ccxix
each other in nature and office, but the organs of which it is proposed to
consider generally the structure in the present chapter, are those devoted
to the function of secretion.
By secretion is meant a process in an organised body, by which various
matters, derived from the organism, are collected and discharged at par-
ticular parts, in order to be farther employed for special purposes in the
economy, or to be simply eliminated as redundant material or waste pro-
ducts. Of the former case, the saliva and gastric juice, and of the latter,
which by way of distinction is often called " excretion," the urine and sweat
may be taken as examples.
Secretion is very closely allied to nutrition. In the one process, as in
the other, materials are selected from the general mass of blood and appro-
priated by textures and organs ; but in the function of nutrition or assimi-
lation, the appropriated matter is destined, for a time, to constitute part of
the texture or organ, whereas in secretion it is immediately discharged at a
free surface. The resemblance is most striking in those cases in which
the waste particles of the texture nourished are shed or cast off at its sur-
face, as in the cuticle and other epithelial tissues.
In man, and in animals which possess a circulating blood, that fluid is
the source whence the constituents of the secretions are proximately
derived : and it is further ascertained, that some secreted matters exist
ready formed in the blood, and require only to be selected and separated
from the general mass, whilst others would seem to be prepared from the
materials of the blood, by the agency of the secreting organ. Among the
secreted substances belonging to the former category, several, such as
water, common salt, and albumen, are primary constituents of the blood,
but others, as urea, uric acid, and certain salts, are the result of changes,
both formative and destructive, which take place in the solid textures and
in the blood itself, in the general process of nutrition. Again, as regards
those ingredients of the secretions which are prepared or elaborated in the
secretory apparatus, it is to be observed, that the crude material may
undergo changes in organic form, as well as in chemical composition.
Evidence of this is afforded by the solid corpuscles found in many secre-
tions, as well as by the seminal cells and spermatozoa produced in the
testicle.
In the structural adaptations of a secreting apparatus, it is in the first
place provided that the blood-vessels approach some free surface from
which the secretion is poured out. The vessels, however, do not open
upon the secreting surface, for their coats, as well as the tissue covering
them, are permeable to liquids ; and the most favourable conditions for
the discharge of fluid are ensured by the division of the vessels into their
finest or capillary branches, and by the arrangement of these capillaries
in close order, as near as possible to the surface. In this way, their coats
are reduced to the greatest degree of tenuity and simplicity, and the
blood, being divided into minute streams, is extensively and thoroughly
brought into contact with the permeable parietes of its containing chan-
nels, as well as effectually and, by reason of its slow motion, for a long
time exposed to those influences, whether operating from within or without
the vessels, which promote transudation.
Such a simple arrangement as that just indicated is sufficient for the
separation of certain substances from the general mass of the blood ; for the
coats of the vessels and tissue super] acent to them are not permeated with
equal facility by all its constituents ; and in certain cases the elimination of
ccxx SECRETING GLANDS.
fluid in the animal body is effected without the necessary aid of any more
complicated apparatus. Thus, the exhalation of carbonic acid and watery
vapour from the interior of the lungs and air-passages, is probably produced
in this simple manner, although the structure of the exhaling membrane
is, for other reasons, complex ; and the discharge of fluid into cavities lined
by serous membranes, which is known to be preternaturally increased by
artificial or morbid obstruction in the veins, may be a case of the same
kiud.
But another element is almost always introduced into the secreting struc-
ture, and plays an important part in the secretory process ; this is the nucleated
cell. A series of these cells, which are usually of a spheroidal or polyhedral
figure, is spread over the secreting surface, in form of an epithelium, which
rests on a simple membrane, named the basement-membrane, or meni-
brana propria. This membrane, itself extra vascular, limits and defines the
vascular secreting surface ; it supports and connects the cells by one of its
surfaces, whilst the other is in contact with the blood-vessels, and it may
very possibly, also, minister, in a certain degree, to the process of secretion,
by allowing some constituents of the blood to pass through it more readily
than others. But the cells are the great agents in selecting and preparing
the special ingredients of the secretions. They attract and imbibe into their
interior those substances which, already existing in the blood, require merely
to be segregated from the common store and concentrated in the secretion,
and they, in certain cases, convert the matters which they have selected into
new chemical compounds, or lead them to assume organic structure. A cell thus
charged with its selected or converted contents yields them up to be poured
out with the rest of the secretion, the contained substance escaping from it
either by exudation or, as is probably more common, by dehiscence of the cell-
wall, which, of course, involves the destruction of the cell itself. Cells
filled with secreted matter may also be detached, and carried out entire with
the fluid part of the secretion ; and, in all cases, new cells speedily take the
place of those which have served their office. The fluid effused from the
blood-vessels, no doubt, supplies matter for the nutrition of the secreting
structure, besides affording the materials of the secretion, the residue, when
there is any, being absorbed.
Examples, illustrative of the secreting agency of cells, are afforded both
by plants and animals. Thus, cells, are found in the liver of various
animals, and especially of crustaceans and mollusks, some of which con-
tain a substance resembling coloured biliary matter, and others particles
of fat. Also, in the urinary organ of mollusks, cells are seen which
inclose little opaque masses of uric acid. The secretion of the sebace-
ous follicles in man often contains detached cells filled with fat ; and,
according to Mr. Goodsir's observation, the ink-bag of the cuttle-fish is
lined with an epithelium, the constituent cells of which are charged with
pigment, similar to that which imparts the dark colour to the inky secre-
tion. This last instance, as well as the production of spermatozoa, is an
example of the formation of new products within secreting cells, a pro-
cess further illustrated in plants, which afford abundant and decided
evidence of the production of young cells, spermatic filaments, starch-
granules, oil, various colouring matters, and other new compounds, in the
interior of cells.
Both in animals and plants, the individual cells which are associated
together on the same secreting surface may differ from each other in the
nature of their contents. Thus, in the liver of mollusca some cells con-
SECRETING GLANDS. ccxxi
tain biliary matter, and others contain fat ; and in the recent soft part of
the epidermis and its appendages, it ia quite common to see cells filled
with pigment mixed with others which are colourless.
A secreting apparatus, effectual for the purpose which it is essentially
destined to fulfil, may thus be said substantially to consist of a simple
membrane, named the membrana propria or basement-membrane (marked a
in the plan, fig. cxxvi. ), supporting a layer of secreting cells on one of its
surfaces (indicated by the dotted line 6, in the figure), whilst finely ramified
blood-vessels are spread over the other (c). But whilst the structure may
remain essentially the same, the configuration of the secreting surface, or
(what amounts to the same thing) of the supporting basement-membrane,
presents various modifications iii different secreting organs. In some cases,
the secreting surface is plain, or, at least, expanded, as in various parts of
the serous, syuovial, and mucous membranes, which may be looked on as
Fig. CXXVI.
Fig. CXXVL PLAN OF A SECRETING MEMBRANE.
a, membrana propria or basement-membrane ; 6, epithelium, composed of secreting
nucleated cells ; c, layer of capillary blood-vessels.
examples of comparatively simple forms of secreting apparatus ; but, in
other instances, and particularly in the special secretory organs named
glands, the surface of the secreting membrane is variously involved and
complicated. An obvious, and no doubt a principal, purpose of this com-
plication is to increase the extent of the secreting surface in a secreting
organ, and thus augment the quantity of secretion yielded by it. No
connection has been clearly shown to exist between the quality of the
secretion and the particular configuration, either internal or external,
of the organ ; on the other hand, we know that the same kind of secretion
that is derived from a complex organ in one animal, may be produced by an
apparatus of most simple form in another.
The more immediate purpose of the complication of the secreting mem-
brane being to augment its surface within a comparatively circumscribed
space, two principal modes are found by which the membrane is so in-
creased in extent, namely, by rising or protruding, in form of a prominent
fold or some otherwise shaped projection (fig. cxxvii., d, e), or by retiring,
in form of a recess (fig. cxxvm., g, h).
The first mentioned mode of increase, or that by protrusion, is not what is
most generally followed in nature, still it is not without example, and, as in-
stances, we may cite the Haversian fringes of the syuovial membranes', the
urinary organ of the snail, which is formed of membranous lamellae, and
perhaps, also, the choroid plexuses in the brain, and the ciliary processes in
the eye-ball, although secretion may not be the primary office of the last-
rneutioned structures. In most of these cases, the membrane assumes the
form of projecting folds, which, for the sake of further increase of sur-
face, may be again plaited and complicated, or cleft and fringed, at their
borders (fig. cxxvir., e, /).
The plan of augmenting the secreting surface by recession or inversion of
the membrane, in form of a cavity, is, with few exceptions, that generally
ccxxii SECEETING GLANDS.
adopted in the construction of secreting glands. The first degree is repre-
sented by a simple recess (fig. cxxvm., g, h), and such a recess, formed of
Fig. CXXVII.
Fig. CXXVII. PLAN TO SHOW AUGMENTATION OF SURFACE BY FORMATION OF
PROCESSES.
a, 6, c, as in preceding figure ; d, simple, and e f, branched or subdivided processes.
secreting membrane, constitutes a simple gland. The shape of the cavity may
be tubular (g) or saccular (h), and, in either case, it is called indifferently a
crypt, follicle, or lacuna, for these names have not been strictly distinguished
in their application. Examples of these simple glands are found in the
raucous membrane of the stomach, intestines, and uterus. The secreting
surface may be increased, in a simple tubular gland, by mere lengthening of
the tube, in which case, however, when it acquires considerable length, the
tube is coiled up into a ball (fig. cxxvm., i), so as to take up less room, and
adapt itself to receive compactly ramified blood-vessels. The sweat-glands,
already described, and the ceruminous glands of the ear are instances of
simple glands formed of a long convoluted tube. But the great means adopted
for further increasing the secreting surface is by the subdivision, as well as
extension, of the cavity, and when this occurs the gland is said to be com-
pound. There is, however, a condition which might be looked on as a step
between the simple and compound glands, in which the sides or extremity
of a simple tube or sac become pouched or loculated (fig. cxxvm., k, I).
This form might be named the multilocular crypt.
In the compound glands, the divisions of the secreting cavity may assume
a tubular or a saccular form, and this leads to the distinction of these
glands into the " tubular," and the " saccular," or " racemose."
The racemose compound glands (fig. cxxvm. c) contain a multitude of
saccules, opening in clusters, into the extremities of a branched tube,
named the excretory duct. The saccules are rounded, pyriform or thimble
shaped, and then often named "cseeal." They are, as usual, formed by
a proper or basement membrane, and lined, or often rather filled, with
secreting cells ; they are arranged in groups, round the commencing
branches of the duct, into which they open both terminally and laterally
(fig. cxxvm. c, n) ; or it might with equal truth be said that the branches
of the duct are distended into cluhters of saccular dilatations. The ulti-
mate branches of the duct open into larger branches (o), these into larger
again, till they eventually terminate in one or more principal excretory
ducts (m), by which the secretion is poured out of the gland. It is from
the clustered arrangement of their ultimate vesicular recesses that these
glands are named "racemose" (in German " traubenformige Driisen") ; and
they, for the most part, have a distinctly lobular structure. The lobules
are held together by the branches of the duct to which they are appended,
and by interlobular connective tissue which also supports the blood-
vessels in their ramifications. The larger lobules are made up of smaller
ones, these of still smaller, and so on, for several successions. The
SECRETING GLAXDS.
CCXXlll
smallest lobules (n) consist of two or three groups of saccules, with a like
number of ducts, joining into an immediately larger ramuscule (o), -which
issues from the lobule ; and a collection of the smallest lobules, united by
Fig. CXX VI II. PLANS OP EXTENSION OP SECRETING MEMBRANE, BY INVERSION OB
RECESSION IN FORM OF CAVITIES.
A, simple glands, viz., g, straight tube ; 7t, sac ; i, coiled tube. B, multilocular
crypts ; k, of tubular form ; I, saccular. C, racemose, or saccular compound gland ; m,
entire gland, showing branched duct and lobular structure ; n, a lobule, detached with 0,
branch of duct proceeding from it. D, compound tubular gland.
connective tissue and vessels, forms one of the next size, which, too, has
its larger branch of the duct, formed by the junction of the ramuli be-
longing to the ultimate lobules. In this way, the whole gland is succes-
sively made up, the number of its lobules and of the branches of its duct
depending on its size ; for whilst some glands of this kind, like the parotid
and pancreas, consist of innumerable lobules, connected by a large and
many-branched duct, others, such as the duodenal glands of Brunuer and
many mucous glands, are formed of but two or three ultimate lobules, or
ccxxiv SECRETING GLANDS.
even of a single one, with a duct, minute in size and sparingly branched,
to correspond. In fact, a small racemose gland resembles a fragment of a
larger one.
A great many compound glands, yielding very different secretions, belong
to the racemose class. As examples, it will be sufficient to mention the
pancreas, the salivary, lachrymal, and mammary glands, with the glauds of
Brunner already referred to, and most of the small glands which open into
the mouth, fauces, and windpipe. From the description given of their
structure, it will be understood why the term " conglomerate glands" has
been applied especially, though not exclusively, to this class. Their smallest
lobules were called acini, a term which has also been used to denote the
saccular recesses in the lobules, and indeed the word adnus, which originally
meant the seed of a berry or the stone of a grape, or sometimes the grape
itself, has been so vaguely applied by anatomists, that it seems better to
discard it altogether.
Of the tubular compound glands, the most characteristic examples are the
testicle and kidney. In these the tubular ducts divide again and again
into branches, which, retaining their tubular form, are greatly lengthened
out. The branches of the ducts are, as usual, formed of a limitary or
basement membrane (membrana propriety, lined by epithelium, and in
contact, by its opposite surface, with capillary blood-vessels. By the
multiplication and elongation of the tubular branches a vast extent of
secreting surface is obtained, whilst, to save room, the tubes are coiled up
into a more or less compact mass, which is traversed and held together by
blood-vessels, and sometimes, also, divided into lobules and supported, as
in the testicle, by fibrous partitions, derived from the inclosing capsule of
the gland. In consequence of their intricately involved arrangement, it
is difficult to find out how the tubular ducts are disposed at their extre-
mities. It seems probable, however, that some are free, and simply closed
without dilatation, and that others anastomose with neighbouring tubes,
joining with them in form of loops ; in the kidney, little round tufts of
fine blood-vessels project into terminal or lateral dilatations of the ducts,
but without opening into them.
The human liver does not precisely agree in structure with either of the
above classes of compound glands. Its ducts, which are neither coiled nor
sacculated, would seem to begin within its lobules, in form of a network
occupying the interstices of the reticular capillary blood-vessels, which also
are peculiar, inasmuch as they receive and transmit venous blood.
Lastly, there are certain little bodies of doubtful nature, connected with
the mucous membrane of the intestine?, and known as the solitary and the
agminated glands, which differ from all those hitherto spoken of, inasmuch
as they are small saccules without an opening. Some anatomists are of
opinion that they discharge their contents, from time to time, by bursting ;
whilst others, without denying the possibility of this, are disposed to take
a different view of these glandular bodies, and (as, at any rate there are no
ducts) refer them to the class of " ductless glands," under which head they
will be again adverted to. The full description of these glands, as well as
of the peculiarities in the structure of the liver and kidney above referred
to, belongs to the details of special anatomy.
Besides blood-vessels, the glands are furnished with lymphatics, which
in the compound glands proceed from lacunar lymphatic spaces within, as
already stated (p. clxxxiii. ). Branches of nerves have also been followed,
for some way, into these organs, and the well-known fact, that the flow of
SECRETING GLANDS. ccxxv
secretion in several glands is affected by mental emotions, shows that an
influence is exerted on secreting organs through the medium of the nervous
system ; and this is further shown by the fact, now ascertained, that an in-
creased flow may be brought on by direct or reflex stimulation of their
nerves. The distribution of these nerves in the salivary glands has been
recently traced by Pfliiger. He finds that dark-bordered nerve-fibres pro-
ceed to the csscal glandular saccules ; that the membranous tube of the
nerve-fibre becomes continuous with the membrana propria of the saccule,
whilst the fibre, retaining its dark borders, passes into the saccule and divides
into fine branches, which run between the nucleated gland-cells lining it,
and finally penetrate the walls of these cells and become connected with
their nuclei. Other nerve-fibres proceeding to the saccules come from
ganglionic or nerve-cells ; these fibres are chiefly pale or non-medullated,
though not without admixture of the dark bordered kind, and are sup-
posed to belong to the sympathetic system. These ganglionic fibres have
also been traced to the gland-cells.
From what has been stated, it will be apparent that the substance of a
gland consists of the ducts, blood-vessels, lymph-lacunse, and a few nerves,
in some cases connected by an interveniug tissue. In the testicle there is a
very small amount of intermediate connective tissue, which, with the aid of
the blood-vessels, holds the tubules but feebly together, so that the structure
is comparatively loose, and readily admits of being teazed out ; but then it
is sufficiently protected and supported by a fibrous capsule on the outside,
atid fibrous septa within the gland. In the racemose glands there is a good
deal of uniting connective tissue, which surrounds collectively each group of
saccules, binds together the lobules, and supports the vessels in their ramifi-
cations. The substance of the kidney contains scarcely any well characterised
fibrous connective tissue, except bundles which here and there accompany
the larger branches of vessels, but there is an abundant, though very deli-
cate, network of retiform tissue in a soft, amorphous matter between the
tubules and blood-vessels, which binds them together.
Parenchyma is a term sometimes employed in describing glandular organs,
though it is less in use now than formerly. It is used sometimes to denote
the solid part of a gland composed of the various tissues already mentioned ;
at other times to signify any substance, of whatever nature, lying between
the ducts, vessels, and nerves. In this last sense, the parenchyma is in
certain glands represented by connective tissue, in others by corpuscles and
amorphous matter, whilst in some it can scarcely be said to exist.
Some glands have a special envelope, as in the case of the kidney and
testicle ; others, as the pancreas, have none.
The ducts of glands ultimately open into cavities lined by mucous mem-
brane, or upon the surface of the skin. They are sometimes provided with
a reservoir, in which the secretion is collected, to be discharged when the
purposes of the economy so demand. The reservoir of the urine receives
the whole of the secreted fluid ; in the gall-bladder, on the other hand, only
a part of the bile is collected. The vesiculse seminales afford another
example of these laterally appended reservoirs. The ducts are constructed
of a basement-membrane and lining of epithelium, and in their smaller
divisions there is nothing more ; but in the larger branches and trunks a
fibro- vascular layer is added, as in the ordinary mucous membrane, with
which many of them are continuous, and with which they all agree in
nature. A more or less firm outer coat, composed of connective tissue,
comes, in many cases, to surround the mucous lining, and between the two,
ccxxvi DUCTLESS GLANDS.
or, at any rate, outside the mucous coat, there is in some ducts a deposit of
non-striated muscular tissue. The epithelium is usually composed of
spheroidal or polyhedral cells at the commencement of the ducts, and is
columnar in the rest of their length, though sometimes flattened or scaly, as
in the mammary gland.
DUCTLESS OR VASCULAR GLANDS.
There are certain bodies which have received the name of glands on
account of their resemblance in general appearance and structure to the
ordinary secreting organs. They differ, however, from the latter in the fact of
their possessing no ducts for the discharge of secretion ; so that the products of
secretive action, if finding any outlet, are compelled to do so by rupture, by
filtration through the tissues, or by re- absorption into the circulating
current. The bodies in question have been termed " ductless " for this
obvious anatomical reason : and " vascular," on certain physiological or
theoretic grounds, as they are supposed to effect some change in the blood
which is transmitted through them.
To this class belong the following bodies : the spleen, the thyroid body,
thymus gland, suprarenal capsules, pituitary body ; and, according to
various authorities, we ought to place in the same category the solitary
closed follicles of the stomach and intestines, the Peyerian glands, the
follicular glands at the root of the tongue, and also the lymphatic glands.
The peculiar structure of each of these organs (except the lymphatic glands,
already treated of) will be considered in its proper place in that portion of
this work which is devoted to special anatomy ; and we have here to give
only a general outline of those structural provisions which are, with more or
less modification, common to them all.
The following may be taken as a general account of the mode in which
their constituent elements are arranged. The form of the gland is deter-
mined by a fibrous, and in some instances dense and firm, investing mem-
brane, which in the larger organs is furnished with prolongations projecting
inwards as septa, giving considerable firmness to the texture, and either
forming loculi or rounded cavities within them, or merely leaving spaces
between the septa, in which the peculiar substance of the gland is placed.
The investing membrane consists of both white and elastic fibres, in vary-
ing proportion, and, in many instances in the lower animals, of non-striated
muscular fibres. Each gland is abundantly supplied with blood-vessels,
both arterial and venous ; the former commonly dividing frequently, but
entering into no anastomosis until they have arrived at their ultimate rami-
fication in a capillary plexus ; the latter (the veins) are usually large, valve-
less, and in some situations appear dilated into sacs ; but this appearance
has been questioned. Lymphatic vessels, proceeding from lacuuse within
the gland, and nerves, exist in very varying proportions.
The blood-vessels as they pass through these glands are in some cases
closely surrounded by a peculiar pulpy substance, varying in amount and
colour at different periods, but generally existing in considerable quantity.
This pulp consists of corpuscles, granular matter, and fat-molecules. The
corpuscles are of very different kinds and vary widely in size ; some, and
those are the best established, resemble lymph, chyle, or pale blood-
corpuscles ; others, free nuclei ; some, of more questionable existence, are
said to be large compound cells, containing in their interior globules closely
DUCTLESS GLANDS. ccxxvii
resembling those of the blood ; others are described as containing many
nuclei, and much granular matter.
These being the general characters of the ductless glands, the varieties
met with in the human body may be arranged as follows.
a. Rounded and closed capsules filled with nucleated cells, nuclei, and
intercellular fluid, and traversed by blood-capillaries ; the capsules placed
singly or in flat patches under a mucous membrane (solitary and agminated
intestinal glands), or surrounding a simple or complex recess lined by and
opening on the surface of a mucous membrane (certain lingual and pharyn-
geal glands, and tonsils) ; it being uncertain whether the contents of the
capsules are discharged by rupture or transudation, or taken up by
absorption.
6. A lobulated organ inclosing a sinuous internal cavity, with no outlet,
filled with a liquid secretion containing corpuscles ; the cavity branching
into the lobules, and ending in the smallest of them, according to one
opinion, by groups of saccular dilatations of its membraua propria, covered
outwardly by capillary blood-vessels, as in the racemose secreting glands.
According to another view the walls of the cavity in an ultimate lobule are
not set round with saccules, but with small solid pellets, formed of aggre-
gated corpuscles similar to those of the fluid, and bounded towards the
outer surface of the lobule by a mernbrana propria, within which is a group
of blood-vessels pervading the corpuscular matter, as in a, (thymus).
c. A glandular body containing different-sized locular spaces formed by a
stroma of fibrous or more or less homogeneous connective tissue : the loculi
containing granules, nuclei, and nucleated cells of various sizes, with inter-
cellular fluid (anterior lobe of the pituitary body and suprarenal capsules),
or lined by a membrana propria and epithelium, and filled with clear
tenacious fluid (thyroid body).
d. An organ containing a peculiar pulp lodged in the interstices of a
trabecular and highly vascular structure ; also capsules with contents as in
a, attached to the vessels, and surrounded by the pulp, which, while con-
taining collections of red blood-corpuscles in various conditions, resembles
generally in nature the matter within the capsules, and is likewise traversed
by fine blood- vessels (spleen).
e. Rounded or oval bodies having in their interior intercommunicating
loculi and intertrabecular spaces, further subdivided by retiform tissue, and
partially occupied by a corpuscular gland-pulp traversed by blood-capillaries ;
everywhere round the pulp a space left for the passage of lymph, communi-
cating with the afferent and efferent lymphatics (lymphatic glands).
The purposes fulfilled by most of the organs referred to are still involved
in great obscurity, and very different opinions are held on the subject by
eminent authorities in Physiology.
DIVISION I.
SYSTEMATIC OK DESCRIPTIVE ANATOMY.
SYSTEMATIC or Descriptive Anatomy embraces the consideration of the
organs of the body in an order arranged according to their nature and con-
nections. It is called Systematic in opposition to Topographic or Demon-
strative Anatomy, in which the various dissimilar organs found in each
region are described together, and which is particularly adapted for the
study of the relative position of parts.
The organs and parts of the body may be regarded from two distinct
points of view, the Physiological and the Morphological.
Viewed in their physiological aspect, they form a series of instruments
fitted for the accomplishment of particular purposes. Thus, for example, the
bones form levers, which are moved by the muscles ; and the combinations
of these in the hand are fitted for grasping, while tho^e of the foot are
adapted for walking.
Considered apart from the functions of its organs, the human body, as
well as all other organisms, exhibits a regular plan in its construction, to
investigate the nature of which is the object of Morphological Anatomy.
That plan cannot be competently examined except with the aids furnished
by the study of Development and Comparative Anatomy. One of the most
general facts connected with the plan of construction of the human body is
its segmented nature, similar sets of parts being placed in succession, so that
the line of their series forms the long axis of the body, and parts found in
one segment or member of the series correspond, often very distinctly, to
parts in other segments.
The segmented plan is that on which are constructed not only vertebrate animals,
or all those which are possessed of a vertebral column, but also the higher invertebrate
classes. It is most manifestly displayed in the class articulata, in some of which
nearly the whole body is composed of a chain of precisely similar segments; while in
others the segments are fused together in groups, so as to form more complicated
structures. In the human body the appearance of segmentation is seen most con-
spicuously in the osseous system ; it likewise pervades the nervous system, and is
observable in some other structures. The trunk of the body is formed by a series
of segments, indistinguishably blended together in some of the systems, but distinct
in others; while the limbs are rather to be regarded as lateral outgrowths connected
with a certain number of segments. Such segments of the body, may be named
vertebral segment*, or, as Goodsir has suggested, somatomes j and to distinguish
sections of the skeleton, the nervous, muscular, or other systems, the terms sderotome,
weitrotome, myotomc, &c , proposed by the same author, may sometimes be con-
veniently employed.
2 OSTEOLOGY.
Correspondence of structural elements in different animals, or in different segments
of the same animal, constitutes what is now generally called liomology. Thus the
wings of birds and the fore limbs of quadrupeds are homologous with the upper limbs
of man, and vertebrae are homologous one with another. To distinguish the
correspondence of parts which lie in series from that which exists between struc-
tures in different animals, Owen has suggested for the former the term homotypy,
and the phrase serial liomology is likewise employed. Thus the bones of the foot
are serially homologous, or homotypic, with those of the hand.
To express resemblance of a general nature, arising from similarity of function, the
term analogy has been adopted by recent authors. While structures fundamentally
similar are regarded as homologous, although the progress of their development
and the purposes for which they are adapted may be different, organs adapted for
similar purposes are said to be analogous, however different in their original
anatomical relations may be the parts of which they are composed. Thus the gills,
being the respiratory organs of fishes, are analogous to the lungs of the air-breathing
vertebrata ; but they are not homologous parts.
DESCRIPTIVE TERMS. As it is the office of descriptive anatomy to indicate with
precision not only the form and structure, but also the position in relation to other
parts of objects which are often irregular and complicated, it is important that it
should have a generally recognised system of nomenclature : hence many words,
expressive of relative position, have acquired a restricted technical sense in which
they are generally used by anatomists. It may be proper to mention here the most
important of those terms. The mesial plane is that in which the body might be
divided into a right and left lateral half; the middle line being the line before and
behind, in which that plane meets the surface of the body. Internal and external
denote relative nearness to and distance from the mesial plane towards either side.
Superficial and deep indicate distance from the surface; and in the expression of this
relation it is well to avoid the use of the terms external and internal, inner and
outer, above and below, or to employ them with the utmost caution, lest they become
a source of confusion. Nevertheless, an exception to this rule is still very generally
made in the instances of some phrases which have been long in use. Thus the
superficial and deep oblique muscles of the abdomen are commonly called external
and internal, and so also with the superficial and deep inguinal rings. Superior,
inferior, above, below, anterior, and posterior have reference to the position of parts
in the erect posture of the body. As, however, the employment of those terms,
though unobjectionable in human anatomy, is liable to give rise to ambiguity in
general or comparative descriptions of structure in man and animals, it is frequently
preferable to substitute others which express position by reference to a region or
structure towards which the part is directed. Thus ventral and dorsal may be often
employed instead of anterior and posterior, and, in the limbs, proximal and distal
instead of superior and inferior. The inferior aspect of the lung may be called
diaphragmatic, the posterior aspect of the gullet vertebral, and so on.
SECTION I. OSTEOLOGY.
THE SKELETON.
The osseous system forms the skeleton or solid framework of the body.
It supports the soft parts, protects delicate organs, and furnishes places of
attachment to the muscles, by winch the different movements are executed.
The osseous parts of the skeleton are bound together by ligaments ; and in
some parts the framework is completed by the addition of cartilages. A
natural skeleton is one in which the connecting parts have been preserved ;
while, in an artificial skeleton, the ligaments and cartilages having been
removed by complete maceration, the bones are united by artificial mechanical
contrivances, and the cartilages are replaced by some other substance.
The number of bones in the skeleton varies at different ages of life, some
SKELETON IX GENERAL. 3
which are originally distinct becoming united together as the process of
ossification proceeds. The following is an enumeration of those usually
reckoned as distinct in middle life :
Single Pairs of T 4. ,
Bones. Bones.
The spinal column consists of twenty -four free vertebrae,
the sacrum, and the coccj-x ..... 26 26
The skull consists of twenty-two bones : of these eight are
cranial, viz., four single bones, the occipital, frontal,
ethmoid and sphenoid ; and two pairs, the parietal
and temporal. Fourteen are facial, viz., two single
bones, the vomer and inferior maxillary bone ; and
six pairs, the nasal, lacrymal, superior maxillary,
malar, palatal, and turbinated .... 6 8 22
There are twelve pairs of ribs, a sternum, and a hyoidbone 2 12 26
The superior extremities consist each of a clavicle and
scapula, humerus, radius, ulna, eight carpal bones,
five metacarpal, and fourteen digital ... 32 64
The inferior extremities consist each of a pelvic bone,
femur, patella, tibia, fibula, seven tarsal bones, five
metatarsal, and fourteen digital .... 31 62
34 83 200
Besides the bones above enumerated, there exist, likewise, three pairs of auditory
ossicles, and, in addition to the patella, various smaller bones called sesamoid. The
auditory ossicles, though enclosed within the temporal bones, may be considered as
belonging to the skeleton. The sesamoid bones are only accessories to the tendons in
which they are developed.
Fig. 1. FIRST DORSAL VERTEBRA, FIRST RIB Fig. 1.
AND CARTILAGE, AND UPPER PART OF THE
STERNUM, SEEN FROM ABOVE, GIVING A VIEW OF
A SEGMENT OF THE VERTEBRATE SKELETON. ^
C, body or centre ; N, vertebral ring or
neural arch ; V, cavity of the chest enclosed by
the ribs or visceral arch.
The segments of the skeleton are BO
disposed as to surround or partially en-
close two cavities of unequal size the
neural and visceral. The neural cavity,
comprehending the cranium and vertebral
canal, is of great width in the head, and
comparatively small in the rest of its
length : it is nearly completely bounded
by bony walls in its whole extent. The visceral cavity, placed in front of
the vertebral column throughout its length, is only imperfectly represented
in the head by spaces enclosed by the bones of the face : its walls, which
are very incomplete, are most perfect in the thorax and pelvis, and leave
large open spaces in the regions of the neck and abdomen. In these several
regions, the relative position of the walls of the neural and visceral cavities
and of their contained viscera remains the same.
I. THE VERTEBRAL COLUMN.
The vertebral column may be considered as the foundation of the
skeleton, not only because it exists in all animals which possess an osseous
system, but because it is the centre round which the other parts are developed
B 2
4 VERTEBRAL COLUMN.
and arranged. Superiorly, it supports the skull ; laterally, it has attached
to it the ribs, through which it receives the weight of the upper limbs ; and
near its inferior extremity it rests upon the pelvic bones, which communicate
the weight of the body to the lower limbs. Besides being a pillar of support
to the rest of the skeleton, it furnishes protection to the spinal cord by
enclosing it in an osseous canal. It is composed of a series of bones, called
vertebrce, the most of which are united together by joints and elastic sub-
stance, and a few by bony connection, in such a manner that, although the
amount of motion allowed between each pair is slight, the aggregate of that
in the whole is sufficient to give the column very considerable flexibility.
The twenty-four upper vertebra) remain separate in the adult, and retain
their mobility : they increase in size from above downwards. They are suc-
ceeded by five others, which rapidly diminish in size from above downwards,
and which are united into one mass, called the sacrum ; beyond the sacrum
are four dwindled terminal members of the series, which as age advances
become likewise united, and form the coccyx. Thus the column may be said
to consist of two irregular pyramids, the common base of which is at the
superior extremity of the sacrum.
THE MOVEABLE VERTEBRAE.
GENERAL CHARACTERS.
The general characters of the vertebrae are best exhibited in those which
are placed near the middle of the column. Those at the extremities present
a greater number of distinctive peculiarities. The following description is
applicable to the great majority of naoveable vertebrae.
Each vertebra has more or less the form of a ring, and presents for con-
sideration a body, arch, and processes.
The body, the large mass in the anterior part of the vertebra, is a short
column, which, when united by elastic intervertebral plates with the others
of the series, contributes to form a firm but flexible pillar of support.
Anteriorly, it is convex forwards, and slightly hollowed from above down-
wards. Posteriorly, it forms part of the ring, and is slightly concave from
side to side. Its superior and inferior surfaces are nearly flat, excepting in
the cervical region, and give attachment to the intervertebral platea. The
vertical surfaces are pierced by numerous foramina for blood-vessels, princi-
pally veins : one or more of these, situated near the middle of the posterior
surface, exceeds the other greatly in size.
The arch consists of two symmetrical halves which spring from the body,
towards its back part, and meet in the middle line behind. The anterior
part of each lateral half, rounded and narrow, is called the pedicle ; the
posterior part is broad and flat, and is called the lamina or plate.
The spinous process or spine projects backwards from the arch in the
middle line. The appearance presented by the linear series of spinous pro-
cesses has led to the application of the name spine to the whole column.
The transverse processes, placed one at each side, project outwards from the
arch. The articulating processes, two superior and two inferior, project
upwards and downwards from the laminae. They are furnished with articular
surfaces, coated with cartilage, which in the superior processes look back-
wards, and in the inferior look forwards, so that the former face the latter
in adjoining vertebrae.
The concavities on the upper and lower borders of the pedicles are named
notches, and constitute by the apposition of those of contiguous vertebrae the
DORSAL VERTEB1LE.
intervevtebral foramina, a series of rounded apertures which communicate
with the vertebral canal, and transmit the spinal nerves and blood- vessels.
The foramen, or space enclosed by the vertebral ring, is bounded anteriorly
by the body, and posteriorly and laterally by the arch. The series of rings
united by ligaments constitutes the vertebral canal, in which the spinal cord
is contained.
Texture. The bodies of the vertebrae are almost entirely composed of
spongy substance, the surface being covered with only a thin layer of compact
tissue. Venous canals, commencing at the larger foramina behind, traverse
the cancellated structure. The arch and processes contain a much smaller
proportion of spongy substance, being covered with compact tissue of con-
siderable density in some places.
CHARACTERS PECULIAR TO GROUPS OP VERTEBR2E.
The moveable vertebrae are divided into three groups, named from the
regions which they occupy, cervical, dorsal, and lumbar.
Each of those groups is marked by distinctive characters. The central
vertebrae of each group differ so much in all their parts from those of
other groups, that any portion, such as the body, ring, or one of the pro-
cesses, is alone sufficient to indicate to which they belong. On the other
hand, the vertebrae at the extremities of each group are assimilated in their
characters to those of the neighbouring group.
In the following description the characteristics of each group, as existing
in its central members, will first be given, and then the slighter differences
of other members will be stated.
DORSAL VERTEBRAE.
The dorsal vertebrae, twelve in number, support the ribs. They are the
simplest in form, and ought to be the first to engage the attention of the
student. Their position is between the cervical and lumbar groups, and
they are also of intern. ediate fcize.
Fig. 2. THE SIXTH DORSAL VERTEBRA. 4
A, viewed from above ; B, viewed from the
right side. 1, the body; 2, the pedicle; 3, the
lamina ; 4, vertebral ring, nearly circular ; 5,
spinous process ; 6, transverse process ; 7, 7',
superior and inferior articulating processes ; c, c',
superior and inferior facets on the body for the
articulation of the head of the rib ; c/, facet on
the transverse process for the articulation of the
tubercle of the rib.
The body is somewhat narrower in front
than behind : its antero-posterior and trans-
verse diameters are nearly equal, and ib
is somewhat heart-shaped, as seen from,
above or below. It is specially characterized
by the presence, at the place where it joins
the arch, of depressed articular sui faces for
the heads of ribs. In the greater number
of instances, there are two costal surfaces
on each Bide, >. ne on the superior, the
other on the inferior border, so placed
that each completes with that of the adja-
cent vertebra a cavity for the head of one
YE11TEBRAL COLUMN.
rib. The body of the first dorsal vertebra is, however, distinguished by having
on each side a complete articular surface for the head of the first rib, besides
a smaller surface on the lower border for one facet of the second rib : the
lower costal surface on the tenth vertebra is usually complete for the tenth
rib ; and on the eleventh and twelfth there is only one articular surface on
each side for the corresponding ribs.
The lamince, shorter and deeper than in the cervical vertebrae, are imbri-
cated or sloped one pair over another like tiles on a roof. The pedicles are
nearly on a level superiorly with the upper surface of the body ; and hence
the superior notches are very shallow, while the inferior notches are com-
paratively deep.
The spinous process, described as bayonet-shaped, is three-sided, elongated,
and sloped, and terminates in a slight tubercle. It is longest and has the
greatest downward inclination in those towards the centre of the series ;
and in them the terminal tubercles are slender, while those of the upper
and lower vertebrae are thickened.
The transverse processes are directed outwards and backwards, and present
in front of the extremity, which is enlarged into a rough tubercle, a small
surface for articulation with the tubercle of the rib. There is, however, no
such surface in the case of the eleventh and twelfth dorsal vertebrae. In
several of the lowest dorsal vertebrae there may readily be recognized on the
extremity of the transverse process, when looked at from behind, three
tubercular elevations, varying somewhat in form and size, and which are
named the external, internal, and inferior tubercles of the transverse pro-
cess. In the twelfth vertebra, in which the transverse process is extremely
short, those three tubercles are most fully developed. They correspond
respectively to the transverse, mammillary, and accessory tubercles after-
wards noticed in ihe lumbar vertebrae. (See Fig. 4, e, f, 6.)
The articulating processes have their cartilaginous surfaces nearly verti-
cal. Those of the superior processes look backwards and slightly upwards
and outwards, those of the inferior processes look forwards and slightly
downwards and inwards. But the superior articular processes of the first
dorsal vertebra are similar to those of the cervical, and the inferior of the
twelfth dorsal to those of the lumbar vertebras.
The ring is nearly circular, and is smaller than in the cervical or the
lumbar region.
LUMBAR VERTEBRA.
The lumbar vertebras are five in number. They are distinguished by
their great size and the absence of costal articulating surfaces.
The body has a greater diameter transversely than from before back-
wards, and viewed from above or below its surface presents a reniforni
outline. That of the fifth lumbar vertebra has the distinctive character of
being considerably deeper at its anterior than at its posterior margin.
The laminae are shorter, deeper, and thicker than those of the dorsal
vertebras. The superior notches are shallow, the inferior deep, as in the
dorsal vertebras.
The spinous process, projecting horizontally backwards, is shaped like the
blade of an axe, but is thickened and rough along the edge which forms
its extremity.
The transverse processes, long and compressed, with a superior and infe-
rior thin margin, project directly outwards. Their extremities lie in series
with the external tubercles of the lower dorsal transverse processes and
LUMBAR AND CERVICAL VERTEBRAE.
Fig. 3.
with the ribs. Behind each, at its base, is a small process pointing down-
wards, which corresponds with the inferior tubercles of the dorsal transverse
processes, and is also called the acces-
sory process. The transverse processes
of the fifth lumbar vertebra are shorter
and thicker than those above, and ars
usually slanted a little upwards.
Fig. 3. THIKD LUMBAR VERTEBRA. ^
A, from above; B, from the right side.
1, the body; 2, the pedicle and inter-
vertebral notch ; 3, the lamina ; 4, the
vertebral ring, somewhat triangular ; 5,
the spinous process ; 6, transverse process ;
7, 7', superior and inferior articulating
processes ; e, the maminillary tubercle, ap-
parently on the superior articulating pro-
cess; /, the accessory tubercle, between
the articulating and transverse processes.
The articulating processes are thick
and strong. Their articular surfaces
are placed vertically and curved so
as to lie in the arc of a circle. Those
of the superior pair, concave, look
backwards and inwards ; those of the
inferior, convex, look forwards and
outwards. The superior pair are fur-
ther apart than the inferior, and em-
brace the infeiior pair of the vertebra above them. From each superior
articular process a tubercle projects backwards, which corresponds with
the internal tubercles of the dorsal
transverse processes, and is also F5 S- 4 -
called the mammillary process. 7 .
The ring is large and triangular,
or widely lozenge-shaped.
Fig. 4. Two LOWER DORSAL AND TWO
UPPER LUMBAR VERTEBRA, ^
with portions of the eleventh and twelfth
ribs of the right side : viewed from behind,
chiefly to show the relations of the tians-
verse processes and adjacent tubercles.
1, body of the eleventh dorsal vertebra ;
5, spinous process of the second lumbar ;
6, costal tubercle of the transverse pro-
cess; 7, 7', superior and inferior articu-
lating processes ; e, mamrnillary, and /,
accessory tubercle ; c, c, two ribs. These
indications are placed only on the alternate
vertebrae to avoid crowding the figure.
CERVICAL VERTEBRA.
The cervical vertebrae are seven
in number. The first and second
are so peculiar in form that they
require a separate description. The
following characters belong to the five lower vertebrae.
The body is small, and broader from side to side than from before back
T-
8 VERTEBRAL COLUMN.
wards. Its superior surface is rendered transversely concave by the upward
projection of its lateral margins, and is sloped down anteriorly. The under
surface, on the contrary, is rounded oif at the sides, while its anterior margin
forms a marked projection downwards.
The lamina are remarkable for their length and flatness. The superior
notches are deeper than the iufeiior.
The spinous process is short, projects horizontally backwards, or is only
slightly depressed, and is bifid at its extremity. That of the seventh,
however, terminates in a tubercle, and is so long as to be readily felt below
the skin, while the others lie more deeply, and are covered with muscles :
hence the name vertebra prominens, applied to the seventh.
The transverse processes are short, and bifid at the extremity. They pre-
sent a deep groove superiorly, in which the spinal nerves lie ; and at the
base are perforated vertically by a round foramen of considerable size. They
have two roots or points of connection with the vertebra, one in front and
one behind the foramen. The posterior root springs from the place of
junction of the pedicle and lamiua, and in so far corresponds with the
dorsal transverse processes ; the anterior root is attached to the body of the
vertebra and ranges in the same line with the ribs. The foramen corresponds
with the space left between the root of a dorsal transverse process and the
neck of the attached rib : it gives passage usually in the upper six ver-
tebrae to the vertebral artery and vein, but in the seventh, though the
foramen likewise exists, those vessels rarely pass through it. The trans-
verse process of the seventh cervical vertebra
presents only a slight appearance of a groove on
its upper surface, and is widened rather than
bifid at its extremity.
Fig. 5. THIRD CERVICAL VERTEBRA. 4
A, from above and slightly from behind ; B, from
the side. 1, the body ; 2 (omitted), the pedicle and
intervertebral notch ; 3, lamina ; 4, vertebral ring, of
a triangular form ; 5, bifid spinous process ; 6, 6*,
transverse process 6, posterior, 6*, anterior tubercle ;
a, foramen in the root of the transverse process trans-
mitting the vertebral artery; 7, 7', articulating processes
7, the superior, 7', the inferior.
B ytriWE^ni^^hT "-^ke articulating processes are large and flat.
Their articular surfaces are situated obliquely,
the superior pair looking backwards, upwards,
and in most of them blightly inwards ; the
inferior pair forwards, downwards, aud in most of them slightly outwards.
The portion of bone between the superior and the inferior articular surface
on each side forms a short vertical pillar.
The ring is of a triangular form, and larger than in either the dorsal or
lumbar vertebrae.
THE FIRST AND SECOND CERVICAL VERTEBRAE.
THE FIRST VERTEBRA, or Atlas, so called from supporting the. head, is
remarkable for the smallness of the parts occupying the position of the
body and spinous process.
The ring, which is large from before backwards, is wider in the posterior
than in the anterior part of its extent. The wide posterior part corresponds
ATLAS AND AXIS VEBTEBBJE. 9
to the rings of the succeeding vertebrae ; the narrower anterior part is occu-
pied by the odontoid process of the axis, and in the recent state is separated
Fig. 6. THE ATLAS VERTEBRA, FRO.M ABOVE. 4
Fig. 6.
1, the anterior .arch, with a tubercle in
front ; 4, the posterior part of the ring, with
5, an indication of a spinous tubercle ; 4', the
anterior part of the ring, containing the odon-
toid process, and indicatiu.2 in front of 4' the
smooth surface on which the process moves
in rotation ; 6, the transverse process with a
slight indication of division into two tubercles ;
7, the condyloid articulating process ; -f inside
it indicates the rounded tubercle to which the
transverse ligament is attached ; a, the fuiamen
in the transverse process ; b, the groove on the
posterior arch for the vertebral artery.
from the posterior by the transverse ligament of the atlas. In front of the
ring is the anterior arch, sometimes called the body, from which projects
forwards the anterior tubercle, while its posterior aspect presents an arti-
cular surface which glides in rotation of the head upon the odontoid process
of the axis. At the sides of the ring are the lateral masses two stout
portions of bone which receive the weight of the head, and present large
articular surfaces on their supeiior and inferior aspects. They are situated
in front of the places of exit of the nerves, and in this and other respects
differ from the articular processes of the five lower cervical vertebrae. The
superior articular surfaces, which receive the condyles of the occipital bone,
are of oval form, converging in front, concave from before backwards, and
looking inwards as well as upwards. At the internal margin of each is a
rounded smooth tubercle with a rough depression, which gives attachment
to the transverse ligament. The inferior articular surfaces are smaller than
the superior pair, flat, nearly circular, looking downwards and inclined a
little inwards.
Tae laminae unite behind to form a posterior tubercle, the rudiment of a
spinous process. They are thick and round in the greater part of their
extent, but at their junction with the lateral masses they are flattened
by a smooth transverse groove on the upper border of each, marking the
course of the vertebral artery as it passes inwards from the foramen of
the transverse process before entering the cranium. This groove is some-
times converted into a foramen by a small arch of bone. It transmits the
suboccipital nerve as well as the vertebral artery, and corresponds with the
notches of the other vertebrae.
The transverse processes project considerably further outwards on each
side than those of the vertebrae immediately following ; they are flattened
from above downwards and somewhat rough, they are rounded at the ex-
tremity, and at the root of each is the foramen which transmits the vertebral
artery.
The SECOND VERTEBRA, Vertebra dentata t or Axis, forms a pivot on which
the head with the first vertebra rotates.
The body is surmounted superiorly by the odontoid process, and is some-
what narrowed and prolonged below to fit into the depression of the body
of the third vertebra. In front it presents a low vertical ridge, with a
depression on each side, to which the upper part of the lougus colli muscle
is attached. The odontoid process (p. deutatus) consists of an enlarged
10
VERTEBRAL COLUMN.
extremity termed the head, and a narrower lower part or neck. It presents
in front a smooth surface for articulation with the atlas, and behind, a
smooth groove to receive the transverse ligament of the atlas. The study
Fig. 7.
Fig. 7. THE Axis VERTEBRA. ^
A, seen from above and behind ; B, seen from the
right side. 1, the body; 4, the vertebral ring
or foramen; 5, the spinous process, bifid and very
large ; 6, the transverse process ; 7, the superior
articulating process ; 7', the inferior oblique articu-
lating process ; I* in A, is placed at the side of the
odontoid process ; in B, in front of it, marking the
smooth surface of articulation with the anterior arch
of the atlas.
of development appears to show that the
odontoid process is in reality the body of
the atlas anomalously connected with the
vertebra dentata. The superior articular
surfaces, placed, like those of the atlas, in
front of the intervertebral groove, lie on the
sides of the base of the odontoid process,
partly on the body and partly on the arch of
the vertebra. These surfaces look upwards
and slightly outwards, and are of considerable
size ; they receive the weight of the head transmitted through the lateral
masses of the atlas. The inferior articulating processes, separated by a notch
from the body, are similar in form and position to those of the succeediug
vertebrae.
The spinous process is very large, rough, and deeply bifid, affording
attachment to several muscles, and is grooved on its inferior surface. The
plates which support it are of proportionate size and strength.
The transverse processes are short, and are scarcely grooved or bifurcated.
The foramen at the root of each is inclined obliquely downwards and
inwards.
THE FIXED OR UNITED VERTEBRAE.
THE SACRUM.
The sacrum (os sacrum) is placed below the last lumbar vertebra, above
the coccyx, and beween the ossa innominata, and forms the upper and
back part of the pelvis. It consists in early life of five vertebrae, which
in the adult are united into one bone. The first of the five is the largest
vertebra in the column ; those which follow become rapidly smaller, and
the fifth is rudimentary. Hence the sacrum is massive above and slender
below, and is triangular in general form, with its base directed upwards.
It is concave and smooth in front, convex and uneven behind. The
direction of its surfaces is very oblique, its pelvic aspect looking downwards
and forwards, and forming at the place where it meets with the last lumbar
vertebra the projection termed promontory. It presents for consideration
a pelvic, a dorsal, and two lateral surfaces, a base and an apex, together
with the sacraL portion of the spinal canal.
The pelvic surface is concave from above downwards, and slightly so from
side to side. It is marked across the middle by four transverse lines or
SACRUM.
11
ridges, which indicate the places of union of the bodies of the five vertebra ;
and at the extremities of these ridges are situated on each side four foia-
mina called anterior sacral, which transmit
the anterior divisions of the sacral nerves.
These foramina are sloped externally into
grooves, and diminish gradually in size from
above downwards.
Fig. 8. SACRUM OP THE MALE, VIEWED FROM
BEFORE, -j
1, 1, four transverse ridges, indicating the place of
original separation of the bodies of the five sacrul
vertebrae; 2, anterior sacral foramina; 3, 4, lateral
surface ; 5, a notch which, with the coccyx, forms a
passage for the filth sacral nerve ; 6, oval surface of
the upper part of the sacrum for articulation with the
body of the last lumbar vertebra; 7, superior articular
processes ; 8, inferior oval surface fur articulation with
the coccyx ; +, inferior lateral angle.
The dorsal surface is convex, very uneven, and somewhat narrower than
the pelvic surface. It presents along the median line four small eminences,
the spinous processes, usually more or less connected, so as to form a ridge.
Below the last spinous process is a triangular opening, the termination of
the spinal canal, the lateral margins of which are formed by the imperfect
laminae of the fifth sacral vertebra, and present a pair of tubercles, the
sacral cornua, which project downwards, and articulate with the cornua or
horns of the coccyx. On each side of the ridge of spines the surface is
smooth and hollowed in the position of the united laminae, and beyond this
surface are two rows of eminences, the inner of which corresponds with the
articular and mammillary processes of the lumbar vertebrae, while the outer
ranges with the transverse processes. In the groove between the two rows
are placed the four posterior sacral foramina, which are smaller than the
anterior, and transmit the posterior divisions of the sacral nerves.
The lateral aspect or border presents anteriorly a large uneven surface,
covered in the recent state with cartilage, which articulates with the ilium,
and is called from its shape the auricular surface : behind this it is rough
and very uneven for the attachment of the posterior sacro-iliac ligaments.
Lower down, the margin of the sacrum is thin and sinuous, giving attach-
ment to the sacro-sciatic ligaments, and terminates in the inferior lateral
angle; below which the breadth of the bone is suddenly contracted, so
that with the adjacent part of the coccyx a notch is formed for the trans-
mission of the fifth sacral nerve.
Fig. 9. UPPER SURFACE OR BASE OF THE
SACRUM OF A MALE, TO COMPARE WITH
FIG. 3, A, OF THE LUMBAR VERTEBRA.
1, the body ; 4, the foramen, ring, or sacral
canal; 5, the spinous process of the first sacral
vertebra ; 6, the part corresponding to a
transverse process, in front of which is the
lai'ge lateral mass ; 7, the superior articulat-
ing process ; 7', the inferior articulating pro-
cess ; e, the mammillary tubercle; /, the
accessory tubercle, slightly seen.
The base, looking upwards and forwards, presents in the middle an oval
12 VERTEBRAL COLUMX.
surface which articulates \vith the body of the last lumbar vertebra, and
behind this, a triangular aperture, which leads into the sacral canal, and
is bounded behind by the sharp depressed border of the laminae of the
first sacral vertebra. On each side of the aperture is an articulating pro-
cess with a vertical articular surface looking backwards and inwards like
the superior articulating processes of the lumbar vei tebrse. In front of this
is a groove which forms part of the last lumbar intervertebral foramen.
The external portion of the base presents posterioily an eminence cor-
responding to the lumbar transverse process, and in front of that a large
smooth convex surface, inclined forwards and continuous with the iliac fosba
of the pelvis.
The apex, formed by the small inferior surface of the body of the fifth
sacral vertebra, is transversely oval, and articulates with the coccyx.
The sacral canal is three-sided, curved with the bone, and gradually nar-
rowed as it descends. It opens below on the posterior surface of the bone,
between the saural cornua where the laminse of the last sacral vertebra do
not unite. From this canal there pass outwards in the substance of the
bone four pair's of inter vei tebral foramina, or short canals, each of which
divides externally into an anterior and posterior sacral foramen.
Curvature. The curve of the sacrum varies greatly in different skeletons : in some
it is slight and confined to the lower end, while in others it is observable in the whole
length, but especially about the middle.
Differences in the sexes. The sacrum of the female body is broader in proportion
to its length than that of the male, so as to approach the form of an equilateral
triangle, and is seldom curved greatly, or in its whole extent. The sacium of the
female also usually inclines backwards from the direction of the lumbar vertebrse to a
greater extent than that of the male.
Varieties. The sacrum is subject to numerous and considerable variations. It not
unfrequently consists of six pieces, and it has been found, but much more rarely,
reduced to four. (Soemmerring, " Lehre von den Knochen urid Biindern, &c.,
herausgegeben von Kudolph Wagner," 1839, p. 128.) It is not fully determined
whether these differences depend on increased development of the first coccygeal
vertebra and on diminished development of the fifth sacral, or whether there may
not be an interposition of a new vertebra in one instance, and the loss of one of the
ordinary series in the other. Occasionally the bodies of the first and second sacral
vertebrae are not joined, although complete union has taken place in every other
part ; and in like manner sometimes a space is left between their arches. The lower
end of the sacral canal may be open to a greater extent than usual, in consequence
of some of the vertebral laminae not having reached the middle line posteriorly :
it has even been found open in its whole extent. (Thomson.) Instances occur in
which the first sacral vertebra has on one side the usual sacral form, while on the
other it has the form of a lumbar vertebra, and occasionally it presents characters on
both sides, intermediate between those of the sacrum and lumbar vertebrse.
THE COCCYX.
The coccyx consists most commonly of four rudimentary vertebrse ; some-
times of five, seldom of only three. The coccygeal vertebrae diminish
gradually in size from above downwards, and are placed in a continuous
line with the lower part of the sacrum.
The first of the series is considerably broader than the others. It presents
superiorly a small oval concave surface which articulates with the apex of
the sacrum, two lateral projections corresponding with those of the last
sacral vertebra, and two bmall processes, termed cornua, corresponding to
a certain extent with articulating processes, which project upwards from its
posterior aspect and rest upon the sacrul cornua. The lateral parts project
COCCYX VERTEBRAL COLUMN AS A WHOLE. 13
outwards, usually forming with the sacrum the notch for the fifth sacral
nerve, and in some instances uniting with the sacrum so
as to form a fifth sacral foramen.
Fig. 10. FOUR COCCTGEAL VERTEBRA, SEEN FRO^T BEFORE. FROM A
MALE SUBJECT OF MIDDLE AGE. ^
The upper piece is separate from the second ; the three lower are
united together in one piece, and separated only by grooves. 1 is
placed above the middle or body of the first coccygeal vertebra ; 1' is
below the fourth piece ; 6 indicates the transverse portion ; 7, the
superior articulating tubercle. J T
The remaining three coccygeal vertebrae are much smaller than the first,
and correspond solely to vertebral bodies. When separate, the second piece
presents an upper and lower flattened surface. The third and fourth pieces
are mere rounded nodules. In middle life, the first piece is usually sepa-
rate, while the three lower pieces are most frequently united into one, the
original separation being indicated only by transverse grooves.
In advanced life, the coccygaal vertebrae, having been previously joined
into one bone, become also united to the sacrum. This union occurs at
an earlier age and more frequently in the male than in the female, but
it is subject to much variation.
THE VERTEBRAL COLUMN AS A WHOLE.
The average, length of the vertebral column is about twenty-eight inches.
Its length varies to a considerable extent in different persons, but not so
much as might be anticipated from a comparison of their stature ; the rela-
tive height of individuals depending more frequently on a difference in the
length of their lower limbs than of the vertebral column.
CURVES. The vertebral column presents four curves, directed back-
wards and forwards. In the neck and loins the convexity is forwards ;
in the back and pelvis it is in the opposite direction. The lumbar
convexity is much greater than the cervical ; and the sacral concavity
is greater than the thoracic. In the dorsal region, there is also very
frequently a slight degree of lateral curvature, the convexity of which in
the great majority of cases is directed towards the right side.
In connection with the thoracic concavity of the column, the bodies of the dorsal
vertebrae are somewhat thinner in front than behind. The pelvic concavity is chiefly
dependent on the diminished vertical diameter of the bodies of the sacrum in front,
and the bending forward of the coccyx. The cervical and lumbar convexities are
attended with a slightly greater thickness of the anterior than of the posterior parts
of the intervertebral discs, and they are in part maintained by the elastic tension of
the ligamenta subflava acting upon the most flexible portions of the column. (W. &
E. Weber. " Mechanik der Mensch. Gewerkzeuge," p. 91 ; and Henle, " Handbuch
der Syst. Anat. des Menschen," vol. i., p. 32.) These curves are connected with the
maintenance of the erect posture. They are absent in infants and increase towards
adult age. They confer upon the column the advantages of a spring, giving it
greater strength and elasticity, and at the same time assist in preserving the
equilibrium of the body.
The lateral curvature in the dorsal region has been supposed by some anatomists
to be connected with the position of the aorta on the left side of the column.
Cruveilhier mentions, in support of this opinion, three cases of transposition of the
aorta, in which the convexity of the lateral curve was directed to the left side.
(Cruveilhier, "Traite d'Anatomie," 4th edit. p. 65.) By a majority of writers this
curve is imputed to the greater muscular action on the right side than the left,
occasioned by the preference usually given to the right arm. This explanation
originated with Bichat. Otto describes a case of right aorta, in which the curve of
VERTEBRAL COLUMN.
Fig. 11
LI
CO/
the column had the usual direction, and in which
the right arm was more muscular than the left.
(" Seltene Beobachtungen," part 2, p. 61 ; see also
K. Quain, "Anatomy of the Arteries," p. 19.)
Fig. 11. VERTEBRAL COLUMN OP AN ADULT MALE,
SEEN FROM BEHIND.
C 1 to above D 1, the seven cervical vertebrse ;
D 1 to above L 1, the twelve dorsal vertebrse; L 1
to above S 1, the five lumbar vertebrse ; S 1 to above
CO 1, tbe sacrum ; CO 1, and below, the four
coccygeal vertebrse. The attention of tbe reader is
called to the transition in the form of the transverse
processes and tubercles indicated in this specimen,
which is well marked.
FORM. On the anterior aspect of the
column, the pillar formed by the bodies of
the vertebrae is seen to become broader from
the axis to the first dorsal vertebra. At this
place it ceases to widen, and even becomes
slightly narrower from the first to about the
fourth dorsal vertebra ; from that level it then
becomes gradually wider down to the base of
the sacrum. The width between the extremi-
ties of the transverse processes is considerable
in the atlas ; it is small in the axis, becomes
greater as far as the first dorsal vertebra,
thence it is again gradually contracted as far
as the last dorsal, and becomes suddenly much
greater in the lumbar region.
On the lateral aspect, the diameter of the
bodies from before backwards is seen to in-
crease most rapidly in the dorsal region. The
tips of the transverse processes of the dorsal
vertebrse, being directed backwards, describe
a greater curvature than the bodies ; while
the spinous processes exhibit a smaller curva-
ture, on account of the middle dorsal set being
most sloped downwards, while those above and
below project backwards.
On the posterior aspect, the spines occupy
the middle line. Those of the dorsal region
are in many instances inclined a little, some
to one side and some to the other. At the
sides of the row of spines are the vertebral
grooves, corresponding to the laminae, and
bounded externally in the cervical and dorsal
regions by the transverse processes, and in the
lumbar by the mammillary processes. They
are broad but shallow in the neck, and become
deep and narrow lower down ; the narrowest
part being at the last dorsal vertebra. Along
the grooves is a series of spaces between the
laminae, which, in the natural condition, are
filled up by the yellow ligaments. The extent
DEVELOPMENT OF THE VERTEBILE.
1-3
of these intervals is very trifling in the
neck and in the greater part of the back ;
it increases in the lower third of the
dorsal, and still more in the lumbar
region. The interval between the occipital
bone and the arch of the atlas is consider-
able, and so is that between the last lumbar
vertebra and the sacrum.
Fig. 12. THE SAME VERTEBRAL COLUMN AS IN
Fia. 11, VIEWED FROM THE LEFT SlDE.
The letters and figures indicate the several
vertebra. The attention of the reader is called
to the different curvatures of the column here
shown, the shape and size of the bodies and
intervertebral spaces, the form and transitions
of the transverse and spinous processes, and the
differences in the costal articulating surfaces.
DEVELOPMENT OF THE VERTEBRAE.
Earliest steps of foetal development as related
to the first formation of the Vertebral Column
and Skeleton. The first step in the formative
process within the ova of vertebrate animals
is the production on the surface of the yolk of
a superficial layer of organised cells, termed
blastoderm, or germinal membrane. In the
progress of development, this substance very
soon comes to be divided into three strata or
layers, which may be distinguished from each
other by their structural differences, and have
been named from their position the upper,
middle, and lower layers of the germinal mem-
brane. The upper and lower layers retain
throughout their simple cellular structure, and
take no share in the formation of the skeleton.
From a part of the upper layer the medullary
rudiments of the brain and spinal marrow are
derived ; while the rest of its extent is the
source of the cuticular covering of the body.
The whole of the deeper layer is taken up in
the formation of the epithelium of the mucous
membranes of the alimentary canal and its
dependencies. But the middle layer has a for
more complex and important destination, as it
furnishes the formative material from which
are developed the rudiments of the osseous,
muscular, and vascular systems, together with
the peripheral nerves, the fibrous coats of the
alimentary canal, and many other parts of the
body.
The earliest indication of embryo-form con-
sists in the production of the primitive trace
and groove, which takes place in the part of
the upper and middle layers to be occupied by
the embryo. The deepening of this groove by
the elevation of its sides lays the foundation
of the cerebro-spinal canal or cavity, and this
is finally closed in superiorly by the meeting
and union of the elevated and approximated
Fig. 12.
16
VERTEBRAL COLUMX.
margins of the groove. At the same time there is enclosed within the cavity the
medullary substance derived from the upper layer, which constitutes the rudiment of
the brain and spinal marrow.
It is below and around this tubular cerebro-spinal cavity, and in the substance of
the portion of the middle germinal layer immediately adjacent to it, that the cranio-
vertebral part of the skeleton takes its origin by steps of which the following is the
briefest possible outline.
Immediately below the cerebro-spinal groove, previous to its closure, there appears
in the substance of the middle layer a linear condensed structure, termed chorda
dorsalis or notochord ; round this at a later period the base of the skull and bodies,
of the vertebra? are developed. The chorda dorsalis may be seen in the embryo-chick
after eighteen hours of incubation, and at corresponding periods of advancement in
the embryoes of mammalia. In the human embryo, although the first origin of this
chord has not yet been observed, there is no reason to doubt its existence ; and from
observations at a later period of development it is certain that the foundation of the
human skeleton is laid in a manner essentially the same as in animals.
Soon after the extension of the two upper germinal layers in the dorsal direction
has given rise, in the manner mentioned, to the neural cavity and its contained
cerebro-spinal axis, the incurvation of all the three germinal layers in a downward or
ventral direction results in the formation of the walls of the visceral cavities of the
body; and thus from the chorda dorsalis as a centre there proceeds upwards a neural
and downwards a visceral arch.
In the middle layer itself, which is destined for the production of the most com-
plicated parts, the thickened portion which is next to the chorda dorsalis on each
side is separated from the part which is more remote, and it is in the inner portion
now mentioned that there are produced at a very early period those structures which
have been called primitive or primordial vertebrae, by embryologists, the formation of
which constitutes the next stage in the progress of the earliest development of the
skeleton. These rudimental structures consist of small dark quadrilateral patches
of condensed germinal substance, to the number of three or four, situated on each
Fide of the chorda dorsalis. The anterior of them corresponds to the atlas vertebra,
and in the subsequent increase of their number, the new ones make their appearance
farther and farther backwards, or towards the caudal extremity.
Fig. 13. This and the three following figures are intended to
illustrate the first formation of the vertebral segments, or "primi-
tive vertebrae," and some of the changes by which the permanent
vertebral and costal arches are produced. F'g. 13 gives in outline
a magnified view of the embryo of the chick about twenty-six hours
after the commencement of incubation, as it lies prone in the centre
of the germinal membrane. 1, 2, 3, cerebro-spinal canal ; 1 2,
the cerebral part ; 2 3, the spinal part, not yet closed in the
caudal region ; 4 4, seven primitive vertebrae, proto- vertebras, or
vertebral segments ; near 2, the rudiments of the heart.
The so-called primordial vertebrae have, however, a more ex-
tended destination than to serve as the basis of formation of the
elements of the vertebral column for each pair of them contains
the rudiments, not only of the osseous and cartilaginous parts
of a vertebra which cross the middle plane, but also in the
thoracic region a portion of a rib, and throughout the whole
extent the central parts of a spinal pair of nerves and the
cutaneous and muscular parts which cover the whole vertebral
region. The process by which these several parts come to be
distinct in the progress of development is somewhat intricate. It
will be sufficient to mention here that, after a considerable change
has occurred in each of the primordial vertebral masses by the
rapid formation of cells within them, each becomes cleft into an
upper and lower (dorsal and ventral) division or plate. The upper constitutes the
basis of the skin and muscles of the vertebral part of the trunk, while the lower or
deeper portion undergoes further division in connection with the development of very
DEVELOPMENT OF THE VERTEBRJE.
dissimilar elements from its substance. In the first place, the outer half of each is
divided by a transverse fissure into two parts, of which the anterior, or that towards
the head, is afterwards converted into the root and ganglion of a spinal nerve ;
Fig. 14, A. Transverse section through
the spinal part of the embryo represented in
fig. 13, at the place whei-e the spinal canal
is. still open, or is only a groove. 1, chorda
dorsalis ; 2, spinal canal or primitive groove ;
2 to 3, medullary plates, continuous with 4,
the corneous layer of the blastoderm ; 5, the
middle layer ; its outer part divided into two
laminae, the upper being the volunto-motory,
in which osseous and muscular plates after-
wards make their appearance, and the lower
being the involuuto-motory or intestino-fibrous
lamina ; 6, the epithelial, or lowest layer of
the blastoderm ; 7, the inner part of the
middle layer, in which the primitive vertebral
segments are developed.
Fig. 14, B (adapted from Reraak and
Kolliker). Transverse section of the lumbar
part of an embryo more advanced, or towards
the fifth day, showing the spinal canal and
spinal marrow closed, the visceral plates and
intestine formed, &c. 1, chorda dorsalis in its sheath ; 2, canal of the spinal marrow;
3, medullary substance of the spinal marrow ; 4, corneous layer ; 5, outer lamina of the
middle layer forming the visceral plates, and along with the corneous layer the amniou
4x5; 5', inner lamina of the middle layer or intestino-fibrous; the figure 5' is placed in
the peritoneal cavity ; immediately above it are seen the rudiments of the Wolffian bodies,
the aorta in the middle between them, and on each side the Wolffian duct; 6, the intestinal
cavity and epithelial layer, extending at 5', 6, into the blastoderm of the yolk-sac.
and the posterior is the source of the transverse process of a vertebra and adjacent
portion of a rib. The inner part of the primordial vertebral mass passes inwards
in two modes: 1st, by its deepest part it passes above and below the chorda dorsalis,
and joining with the corresponding structures from the opposite side, surrounds
Fig. 15 (from Remak and Kolliker). The cervi-
cal part of the primitive vertebral column and
adjacent parts of an embryo of the sixth day,
showing the division of the primitive vertebral seg-
ments into permanent vertebral arches, rudiments
of the spinal nerves, &c. 1, 1, chorda dorsalis in
its sheath, pointed at its upper end ; 2, points by
three lines to the original intervals of the primi-
tive vertebrae ; 3, in a similar manner indicates the
places of new division into permanent bodies of ver-
tebrae ; c indicates the body of the first cervical
vertebra; in this and the next the primitive divi-
sion has disappeared, as also in the two lowest
represented, viz., d and the one above ; in those
intermediate the line of division is shown : 4, points
in three places to the vertebral arches ; and o, similarly
to three commencing ganglia of the spinal nerves : the
dotted segments outside these parts are the muscular
plates.
the chorda ; 2nd, its more superficial part completes the formation of a ring, or
a part of a cylinder, round the spinal cord. This may be considered as the
18
VERTEBRAL COLUMN.
membranous stage in the development of the vertebral column. It may be proper
to remark that there is no similar original division in the cephalic portion of the
primordial skeleton, but the chorda dorsalis is prolonged for a short distance into the
middle of the basilar part.
The process of breaking up of the primordial vertebral masses above referred to is
followed by a reconstruction, as it were, of the vertebras, which consists in this that
in the cylinder investing the chorda dorsalis the lines of separation of the primordial
vertebral masses fade away, while midway between them new lines appear, marking
the limits of the permanent vertebrae ; and thus each permanent vertebra is formed
from pai'ts of two of the primordial masses ; the arch, the transverse processes and
part of the ribs, together with half the body, being derived from one primitive
vertebra, and the remaining half of the body together with the corresponding pair of
nerves proceeding from a part of the next primordial mass in succession.
In the human embryo, the vertebral column begins to become cartilaginous in the
sixth or seventh week. The cartilage spreads rapidly over the bodies, but much
more slowly into the arches, in which the
Fig. 1 6. union of the cartilages of opposite sides is
not completed till during the fourth month
A &!;:' &'A (Kb'lliker). At the period of the first appear-
ance of the cartilaginous bodies, the chorda
dorsalis consists of a solid column of large
thin-walled cells, surrounded by a transpa-
rent sheath; but it becomes constricted, and
gradually dwindles within each vertebral
body, while it remains more fully developed
in the intervertebral spaces, and enters into
the formation of the intervertebral discs.
Fig. 16, A & B (from Kolliker). SECTIONS
OP THE VERTEBRAL COLUMN OP A HUMAN
FCETUS OP EIGHT WEEKS.
A, transverse longitudinal section of
several vertebrae. 1, 1, chorda dorsalis, its
remains thicker opposite the intervertebral
discs ; 2 is placed on one of the bodies of
the permanent vertebrae ; 3, on one of the
iutervertebral discs.
B, transverse horizontal section through
a part of one dorsal vertebra. 1, remains
of the chorda dorsalis in the middle of the
body ; 2, arch of the vertebra ; 3, head of
a rib.
OSSIFICATION. The ossification of each typical vertebra proceeds from three
principal nuclei. One of these, which is occasionally double at first, appears in the
middle of the cartilage, and is afterwards converted into the main part of the body ;
the other two, placed one on each side, appear opposite the roots of the transverse
processes, usually a little earlier than the nucleus of the body ; and form the arch and
processes, together with an angular part on each side of the body, namely, that part
which in the dorsal region supports the heads of the ribs. At different periods
subsequent to the age of puberty, five epiphyses, or supplementary centres of ossifica-
tion, are added. Three of these are small portions of bone, placed on the tips of the
spinous and transverse processes : the other two are thin circular plates, one on the
upper, the other on the lower surface of the body, chiefly at its circumference. In
the lumbar vertebrse two other epiphyses surmount the mammillary processes. The
transverse process of the first lumbar vertebra is sometimes observed to be developed
altogether from a separate centre. Most of the anterior divisions of the cervical trans-
verse processes are ossified by the extension into them of osseous substance from
the neighbouring posterior part of the process and from the arch ; but that of the
seventh usually presents a separate osseous nucleus, and small nuclei have also been
observed by Meckel in those of the second, fifth, and sixth vertebrae.
OSSIFICATION OF THE VERTEBRA. 19
In the atlas, the lateral masses and posterior arches are ossified from a pair of
centres corresponding to those in the arches of the succeeding vertebrae. In the
anterior arch one or two separate nuclei appear soon after birth and even three have
been observed. There is frequently a small epiphysis on the posterior tubercle.
Fig. 17. ILLUSTRATES THE OSSIFICA-
TION OP THE VERTEBRA.
A, foetal vertebra, showinsr the three
primary centres of ossification ; 1, 2,
for the pedicles, laminae, and processes ;
3, for the body.
B, dorsal vertebra from a child of
two years, as seen from above ; 1 & 2
are seen to have encroached upon the
body at *, and into the articular and
transverse processes, and to have united
behind in the spinous process, leaving
cartilaginous ends.
C, dorsal vertebra at about sixteen or
seventeen years, showing the epipbyses
on the transverse processes, 4 & 5, and
spinous process, 6, and the upper epi-
physal plate of the body, 7.
D & E, parts of a lumbar vertebra of
about the same age, showing, in addi-
tion to the foregoing, 8, the lower
epiphysal plate of the body; 9 & 10,
the epiphyses of the superior articular
processes (mammillary tubercles).
Fig. 17.
In the axis there appear, about the same time as in the other vertebrae, a pair of
osseous centres in the arch, one or two in the body (Cruveilhier), and shortly after-
wards a pair in the odontoid process which very soon unite together. At birth, the
odontoid process is of larger size than the body, from which it is still distinct ; and
its general appearance confirms the evidence of comparative anatomy, that it is to be
regarded as the body of the atlas.
Fig. 18. OSSIFICATION OF THE ATLAS
AS SEEN FROM ABOVE.
A, the atlas before birth ; 1 & 2, ossi-
fied deposits in the posterior parts of the
arch ; the anterior part is cartilaginous.
B, the atlas of a child in the first
year ; 1 & 2, as before ; 3, the point of
ossification in the anterior arch.
Fig. 18.
Fig. 18.* OSSIFICATION OF THE Axis
AS SEEN FROM THE FRONT.
A, the axis of the fcetus of seven
months, showing at 3 the centre for the
body, and at 4 & 5 two centres for the t
base of the odontoid process.
B, the axis shortly after birth, showing
at 1 & 2 the centres for the arch ; 3, the
centre for the body ; 6, the two centres
of the odontoid process united into one.
Fig. 18.*
The sacral vertebrae present the three ordinary great centres of ossification, viz.,
one in the body, and a pair in the arch ; but in each of the first three or sometimes
four sacral vertebrae the anterior part of the lateral masses on each side is formed
c 2
20
VERTEBRAL COLUMN.
from an additional centre. On the body of each sacral vertebra, epiphysal plate?
are formed at a later period, as in other vertebra. To complete the ossification
of the sacrum, there are also formed on each side of it two flat and irregular plates,
of which one extends over the first three vertebrae, while the other connects the
last two.
Fig. 39.
Fig. 19. OSSIFICATION OP THE SACRUM.
A, sacrum of a foetus before six months, seen from the front, showing the ossific
nucleus in the body of each vertebra, from 1 downwards.
B, sacrum of a child at birth, showing three pairs of additional nuclei for the lateral
masses, 2, 2, close above the sacral foramina.
C (one-fourth of the size of nature), sacrum of a person of about twenty-five years of
age. At 3 & 3, epiphysal plates are still visible above and below the first vertebral
piece, and the fissures still remain between the first and second and the second and third
lateral pieces ; at 4 & 4' are shown the lateral epiphysal plates.
Each of the coccygeal vertebrae is usually ossified from a single centre ; but occa-
sionally one of the first three contains two granules placed side by side.
Progress of Ossification in the Vertebral Column. The deposit of bone in the
arches of the vertebrae takes place first in those belonging to the upper end of the
column, and gradually proceeds downwards. In the bodies, it first occurs in the
lower part of the dorsal region (about the ninth dorsal vertebra) ; and from that
the process is extended upwards and downwards, reaching last of all the atlas and the
coccyx, neither of which ossify till after birth. But though the nuclei of the lower
dorsal vertebrae are the first to appear, they are soon surpassed in size by those below
them ; and in the foetus at birth the relative size of the nuclei corresponds with that
of the fully-grown vertebrae.
In the subjoined table are stated the ages at which the osseous centres of the
vertebral column appear and the steps of union take place. But it is to be observed
that it is only attempted to state these ages approximately, both because of the great
difficulty, in most instances, of determining the age of the human foetus with
accuracy, and because of a certain amount of variety which probably exists in the
rapidity of the growth of bone in different cases. (See Albinus, " Icones Ossium
foetus," p.
" On the Skeleton,
; Meckel, in his " Archiv " vol. i. 1815, p. 648, tab. vi. ; Humphry,
.eton," p. 132 ; Aitken, " Growth of the Recruit," 1862.)
PERIODS OF OSSIFICATION OF THE VERTEBRAE.
In the vertebrae generally
The three primary centres appear in the 7th or 8th week (foetal life).
The epiphyses of the processes appear in the 18th year or later.
The epiphysal plates of the body appear in the 18th or 20th year.
The two centres of the arch unite in the first year.
COMPARISON OF VERTEBRAE. 21
In the vertebrae generally
The arch and the body unite in the 3rd year.
The vertebra and its epiphyses unite in the 25th year or later.
In the atlas
Ossification of the anterior arch appears in the 1st year.
The two centres of the posterior arch unite in the 3rd year.
The anterior and posterior arches unite in the 5th or 6th year.
In the axis
The centre of the body and (a little later) the centres of the odontoid process
appear in the 6th month.
The body and odontoid process unite in the 3rd year.
In the sacrum
The additional lateral centres appear from the 6th to the 8th month.
The lateral epiphysal plates appear from the 18th to the 20th year.
The body and arch unite in the 5th vertebra in the 2nd year.
The body and arch unite in the 1st vertebra in the 5th or 6th year.
The lower vertebrae unite with one another in the 18th year.
The upper vertebrae unite with one another in the 25th year or later.
In the coccyx-
Ossification of the 1st vertebra appears about the time of birth.
Ossification of the 2nd vertebra appears from the 5th to the 10th year.
Ossification of the 3rd vertebra appears from the 10th to the 15th year.
Ossification of the 4th vertebra appears from the 15th to the 20th year.
THEORETICAL COMPARISON OF THE VERTEBRA.
The study of the correspondence of parts in different vertebrae, or of their homology,
involves complicated questions, which cannot be competently discussed without refer-
ence to the various forms found throughout the vertebrate classes of animals. But
there are some points connected with this subject to which the attention of the
student of human anatomy may here be briefly directed.
In considering the serial relations of the bodies of the vertebrae, it is necessary to
distinguish the masses formed round the chorda dorsalis the centra from the angular
portions derived by ossification from the arch. The only peculiarities in the series of
centra are to be found at or near the extremities of the column. One of these, of less
note, is presented by the first coccygeal vertebra, the cornua and lateral projections of
which, although ranged in series with parts which in the preceding vertebrae are derived
from the osseous nuclei of the arch, are, nevertheless, ossified from the centrum. The
other peculiarity presented by the atlas and axis is of a more remarkable kind.
The odontoid process of the axis is the true centrum of the atlas, disguised by
remaining distinct from the rest of the vertebra to which it belongs, and becoming
adherent to the centrum of the succeeding vertebra. The main proofs that this view-
is correct are, 1st, that the odontoid process originates in cartilage distinct from the
proper centrum of the axis ; 2nd, that the remains of the chorda dorsalis have been
traced through the odontoid process to the occipital bone ; and 3rd, that in early life,
and in certain animals (especially turtles), the odontoid process is similar in appearance
to the succeeding centra. The anterior nucleus of the atlas must, therefore, be regarded
as a precentral or subcentral structure. (Rathke, " Entwicklungsgeschichte der
Matter," p. 120; and "Entwickl. der Schildkrb'ten," p. 77.) It is proper to observe that
both sets of the articular surfaces of the atlas and the superior pair belonging to the
axis are placed upon those parts which in succeeding vertebrae form the angles of the
bodies ; these articular surfaces, therefore, correspond in position, not with the smooth
facets of the articulating processes, but rather with those for the heads of the ribs in the
dorsal vertebrae. This is seen not only from their position in front of the trunks of
the spinal nerves, and from the superior articular surfaces of the axis actually abutting
on the centrum, but also from the condition of parts in many animals. Thus, in
birds and reptiles the lateral masses and anterior nucleus of the atlas unite to form a
mesial disc, which articulates with the body of the axis in front of the odontoid
process and with a single condyle on the occipital bone, while at the same time the
axis and atlas are likewise connected by articulating processes placed behind the
nerves and in series with those which follow.
22 VERTEBRAL COLUMN.
On examination of the series of transverse processes, a certain amount of correspon-
dence cannot fail to be noticed between the anterior divisions of those of the cervical
vertebras and ribs; especially when it is considered that in certain instances those of
the seventh cervical vertebra are replaced by ribs which are articulated in two places
with the vertebra; and that in the neck of saurian reptiles short ribs are found very
similar in appearance to the anterior divisions of the transverse processes in the
human subject. On the other hand, these processes differ from ribs in being for the
most part ossified in continuity with the arch ; and on that account some anatomists
prefer to compare them with the costal facets on the dorsal vertebrae, and with pro-
cesses on which in birds and reptiles those facets are elevated. The transverse, mam-
millary, and accessory processes of the lumbar vertebrae lie in series, as has been
seen, with the three sets of tubercles on the transverse processes of the twelfth and
other dorsal vertebrae, whence it may be argued, as has been done by Retzius, that
the whole transverse process of a dorsal vertebra corresponds to the three processes
of a lumbar vertebra. At the same time, the mammillary processes are not mere
subsidiary parts developed on the transverse processes, for in some animals, as the
hedgehog and the armadillo, they are of much greater size than the transverse pro-
cesses themselves, continue distinct from them in nearly the whole length of the
thoracic region, and may be seen to lie in series with prominences on the articulating
processes of the cervical vertebrae. The lumbar transverse processes are not without
a certain degree of correspondence with ribs, which is illustrated by the first of the
series being sometimes replaced by a short thirteenth rib on one or both sides, and is
also indicated by the existence on the upper borders of the lumbar transverse processes
of grooves, sometimes pretty distinct, which lie in series with the intervals between
Fig. 20. Fig. 20. OSSEOUS PART OF THE FIRST- VERTEBRA OF THE
SACRUM OF A PERSON OF FOUR OR FIVE YEARS OLD. J
1, the body ; 2, 2, the large lateral masses between
which and the body and the transverse processes deep
fissures are seen running backwards.
the necks of the ribs and the dorsal transverse processes.
In the sacrum, the special lateral centres of ossification
in the three upper vertebrae may, very probably, be
regarded as costal elements. (Retzius, "Muller's Archiv," 1849 ; J. Miiller, " Vergl.
Anat. der Myxinoiden;" August Miiller, "Muller's Archiv," 1853; Humphry,
"Treatise on the Human Skeleton ; " Cleland, in " Nat. Hist. Review," 1861 and 1863.)
It is not to be wondered at that the vertebral column, from its being the most
regularly segmented structure in the body, as well as from its forming the basis of the
osseous system, should have held a prominent place in the various schemes, according
to which it has been attempted to resolve the skeleton into a certain number of
elements, repeated in modified forms in the different segments. Among the various
schemes of this description may be mentioned those of Oken, Carus, Geoffroy St.
Hilaire, Owen, Maclise, and Goodsir. (Oken, "Physiophilosophie,"and in "Isis," 1817,
1819, 1820 ; C. G. Carus, " Lehrbuch der Zootomie," 2nd edit. ; Geoffroy St. Hilaire,
"Philosophic Anatomique;" Owen, "On the Archetype and Homologies of the
Vertebrate Skeleton ; " Maclise, " Comparative Osteology," and the Article " Skele-
ton " in " Todd's Cyclopaed. of Anat. and Physiol. ; " Goodsir, " Edinburgh New
Philosophical Journal," 1857, p. 118.)
Based upon morphological views, there has likewise been introduced by Owen
a system of nomenclature, which being adhered to in his descriptive writings,
and adopted more or less by various English writers, demands attention. In that
system the word vertebra is employed to signify a segment of the skeleton, the term
centrum is preserved in its usual signification, the laminae are called neurapophyses,
the spine the neural spine, the articulating processes zygapopliyses, the ribs pleura-
pophyses, the mammillary processes metapophyses, and the accessory processes
anapophyses. Two descriptions of transverse processes are distinguished, viz., the
diapophyses and the parapoplyses ; the dorsal transverse processes and the posterior
parts of the cervical transverse processes being examples of the first, while the anterior
parts of the cervical transverse processes are referred to ^the second. The ideal
THE THORAX. STERXUM.
23
arrangement named by Owen the " typical vertebra " is completed by the addition
to the parts now mentioned of a pair of hcemapophyses and a hcemal spine, situated
in front of the centrum, as the neurapophyses and neural spine are placed behind ;
but in the thorax, according to his views, the .haemapophyses are supposed to be
transplanted to the extremities of the pleurapophyses, and form the costal cartilages,
carrying with them the sternum or series of haemal spines.
However 'interesting these views may be, and however expedient the adoption in
Comparative Anatomy of some such words, expressive of anatomical relations,
more especially when it shall appear that the doctrines suggesting the terminology
are sufficiently established ; yet, as these are still imperfect, and as the names
by Avhich most parts of the human body are commonly designated have been long
in use, and are very generally understood, it seems premature for the present
to attempt a theoretical reformation of the nomenclature of human descriptive
anatomy.
II. THE THORAX.
The parts -which enter into the construction of the thoracic part of the
skeleton are the dorsal vertebrae already described, the sternum, the ribs,
and the costal cartilages.
THE STERNUM OR BREAST-BONE.
The sternum (os pectoris, os xiphoides) is situated in the median line at
the fore part of the thorax, in a sloping position, inclined downwards and
forwards. It is connected with the rest of the trunk by the costal cartilages
Fig. 21.
Fig. 21. THE STERNUM OP A MIDDLE-AGED . ,,
MAN. I m " *^ n
A, from before, 1, 2, 3, 4, 5, 6, & 7, the
articular surfaces for the corresponding costal
cartilages; 8, manubrium or upper piece, still
slightly separate from the body ; 9, middle
of the body ; 1 0, ensiform portion, osseous,
and united to the body; 11, inter-clavicular
notch ; 1 2, articular notch for the clavicle,
B, the same sternum viewed from the
right side, showing the general convexity of
the bone forwards. The different facets of
articulation of the clavicle and costal carti-
lages will be distinguished by their position
in comparing the figure B with A.
of the seven highest pairs of ribs, and
gives attachment to the clavicles. It
consists originally of six segments.
The first of these usually remains
distinct up to middle life, and is
called the manubrium ; the succeed-
ing four are united into one in the
adult, and form the body ; the sixth
generally remains cartilaginous up
to the period of puberty, and some-
times partially so even to advanced age, and is called the xiphoid, or
ensiform process, or cartilage : in middle life it is most frequently ossified
and united by bone to the body.
The sternum is flattened from before backwards, and presents a slight
vertical curve with the convexity in front. It is of unequal width, being
21 BONES OF THE THOEAX.
broad at the upper part of the manubrium, considerably narrower at the
lower end of that portion and in the following segment, somewhat wider near
the lower than at the upper end of the body, and finally compressed and
narrowed where the body joins the ensiform cartilage. It consists of light
cancellated texture, with a thin covering of compact bone, so as to be liable
to crushing from violence.
The manubrium is the thickest part of the sternum. Its superior border
is divided into three deep notches ; the middle one is named the incisura,
furcula, or interclavicular notch ; the lateral ones form two depressed articular
surfaces directed upwards and outwards, for articulation with the clavicles.
Each lateral border presents superiorly a rough depression close to the
clavicular surface, but looking directly outwards, which receives the cartilage
of the first rib ; and, at its inferior angle, a small surface which, with a
similar one on the second segment, forms a notch for the cartilage of the
second rib. The inferior margin is straight, and united by intervening
cartilage to the upper margin of the second segment.
The body is marked on its anterior surface by three slight transverse
elevations, which mark the lines of junction of its four component parts.
Its posterior or thoracic surface, together with that of the manubrium, is
of more uniform smoothness. The lateral margins present each five notches
for the reception of costal cartilages, and a small surface superiorly, which,
with the similar depression on the manubrium, forms the notch for the
second costal cartilage.
The notches for the third, fourth, and fifth costal cartilages are opposite
the lines of junction of the four segments of the body of the sternum ;
those of the sixth and seventh are placed close together on the sides of
the inferior segment, that for the seventh being frequently completed by the
ensiform cartilage.
The lower segment of the bone, often called ensiform cartilage, varies
considerably in different individuals. In its simplest form it is a thin
spatula-like process projecting downwards between the cartilages of the
seventh ribs. It is, however, subject to very frequent varieties of form ;
being sometimes bent forwards, sometimes backwards, often forked, and
sometimes porforated. It projects into the aponeurosis of the abdominal
muscles.
The sternum is subject to many varieties. It is sometimes divided vertically in
the whole or a part of its length. It is not unfrequently much shorter than usual, and
indented at its lower part, as occurs especially from the pressure of the cobbler's last.
Two episternal nodules have been found in some rare cases surmounting the
incisura of the manubrium. (Breschet, " Annales des Sciences Naturelles," 2d series,
v. 10, Zoologie, p. 191 ; and Luschka, "Die Halsrippen und die Ossa suprasternalia,"
Vienna, 1859.) Their position is indicated by the asterisks (**) in figure 24, E.
They derive an additional interest from the occurrence of suprasternal bones in
reptiles and monotremata.
THE KTBS.
The ribs (costce) are twelve in number on each side. They form a series
of arched and highly elastic bones, which extend outwards and forwards
from the vertebral column, and form the lateral walls of the thorax. Their
anterior extremities give attachment to cartilaginous prolongations the
costal cartilages, the first seven pairs of which pass forward to the sternum.
On this account the first seven pairs of ribs are called sternal, or true ribs,
while the remaining five pairs are called asternal, or false ribs.
RIBS. -j
CHARACTEES COMMON TO MOST OF THE RIBS. These are best marked in
the ribs near the middle of the series. The posterior extremity is thickened,
and is termed the head or capitulum ; it presents a superior and an inferior
oblique articular surface for articulation with the bodies of two vertebra, and,
between them, a slight ridge, to which the interarticular ligament is attached.
At a little distance from the head, and separated from it by the neck, is the
tubercle, which is directed backwards, and presents a smooth surface for arti-
culation with the transverse process of the inferior of the two vertebrae with
which the head is connected, and, outside that, a roughness marking the
insertion of the posterior costo- trans verse ligament. The part termed the
necfc, between the head and the tubercle, is slenderer than the rest of the
rib. The whole extent beyond the tubercle constitutes the body. It becomes
laterally compressed, and wider from above downwards, towards the anterior
extremity. Outside the tubercle, between it and the most convex part of
the body, is a rough line, which corresponds to the outer border of the
erector spinee muscle, and which is termed the angle, because at this point
the curve of the rib is more sudden, and changes from an outward and
backward to a forward direction. The inferior border presents on its
inner aspect a groove, in which lie the intercostal vessels and nerve, and
which is best marked opposite the angle, and disappears in front. The
anterior extremity is hollowed at its tip into an oval pit, into which the
costal cartilage is implanted.
Fig. 22.
Fig, 22. THE FIRST, SIXTH, AND TWELFTH RIBS OP THE RIGHT SIDE. |
A, the sixth seen from above and the outer side ; B, the same rib viewed from below
and within ; C, the first rib viewed from above and without ; D, the twelfth rib viewed
from above and within.
1, the head in C & D, the ridge between the two facets of the head * *, in B ; 2, the
neck ; 3, the tubercle, in B presenting the rough tubercle and the smooth facet for
articulation with the transverse process ; 4, the lower border with the ridge and subcostal
groove ; 5, the upper border ; 6, the oval pit for the attachment of the costal cartilage ;
7, in the first rib, C, the scalene tubercle or spine, and near it the smooth groove for the
subclavian artery.
Inclination and Curves. There is a general inclination of the ribs
downwards from the head to the anterior extremity. This slope is greatest
between the head and angle ; beyond that point it is diminished, and it is
again increased further forwards, and diminished at the anterior extremity.
The curve of the ribs is much more marked towards the back part than in
26 BONES OF THE THORAX.
front, and is most so in the neighbourhood of the angle. At first the rib is
directed backwards as well as outwards. Besides the main curves now
mentioned the rib is somewhat twisted on itself, so that the two extreme
portions cannot be made to rest at the same time on a flat surface. It
follows, from the same twisting in the majority of the ribs, that while their
surfaces are vertical posteriorly, they are sloped upwards and inwards at
the anterior part.
CHARACTERS PECULIAR TO CERTAIN BIBS. The ribs increase in length from
the first to the eighth, and decrease from the ninth to the twelfth, so that the
last is little longer, often even shorter, than the first. The first rib is the
broadest, and after it the middle ones ; the twelfth is the narrowest. The
distance of the angle from the tubercle increases gradually from the second
to the eleventh ; in the first the angle coincides with the tubercle, in the
last it is not perceptible.
The first rib is shorter and broader than any of the others. Its direction
is slightly inclined, and its surfaces lie nearly in the same flat plane. Its
superficial and thoracic surfaces look respectively upwards and downwards.
The head is small, and presents a single articular surface. The neck is
round and slender. It articulates with the body and transverse process of
the first dorsal vertebra alone. On the snpeiior or superficial surface are two
very slight smooth depressions with an intervening rough mark, and a
considerable rough surface behind. The rough surface marks the attachment
of the scalenus medius muscle, the posterior depression the position of the
subclavian artery, the anterior depression the subclavian vein ; and the inter-
vening slight elevation, frequently terminating in a sharp spine on the inner
edge, indicates the attachment of the scalenous anticus muscle.
The second rib is longer than the first, and presents externally a prominent
roughness which marks the attachment of the senatus magnus.
The eleventh and twelfth are distinguished as the free or floating ribs,
because their cartilages are pointed and unattached in front. They have no
groove on the inferior border, no articular tubercle, and only one articulating
surface on the head. The mark of the angle is scarcely perceptible on the
eleventh, and is absent from the twelfth.
Varieties. The number of the ribs is sometimes increased to thirteen on one or
both sides. The supernumerary rib is most frequently very short, and is formed in
connection with the transverse process of the first lumbar vertebra, or occasionally
with the seventh cervical : in the latter case the additional rib has a double attach-
ment, viz., to the body and transverse process of the vertebra. The number is
sometimes diminished to eleven pairs by the absence of the twelfth. Ribs likewise
occur greatly expanded or forked at their anterior extremities ; and occasionally two
or more ribs are united together in a part of their extent by their margins.
The COSTAL CARTILAGES are continuations of the rtt>s. Their breadth
diminishes gradually from the first to the last, whilst the length increases
as far as the seventh, after which it becomes gradually less. Their line of
direction varies considerably. The first descends a little, the second is
horizontal, and all the rest, except the last two, ascend more and more from
the rib towards the sternum as they are situated lower down. The external
or costal extremity, convex and uneven, is implanted into and united with
the end of the corresponding rib. The internal extremities of the upper
seven (except the first), are smaller than the external and somewhat pointed,
and fit into the corresponding angular surfaces on the side of the ster-
num, with which they are articulated in synovial cavities. Each of the
cartilages of the first three asternal ribs becomes slender towards its ex-
THORAX AS A WHOLE. DEVELOPMENT.
27
tremity, and is attached to the lower border of that which is next above it.
The last two are pointed and unattached.
The first cartilage, which is directly united to the sternum without
articular cavity, usually becomes more or less ossified in the adult male ; and
the others likewise exhibit a considerable tendency to ossify in advanced
life. This tendency is not so great in the female, in whom costal respiration
is generally more extended than in the male.
THE THORAX AS A WHOLE.
The thorax is of a somewhat conical shape, with convex walls. Its upper
inlet is contracted, and bounded by the first dorsal vertebra, the first pair of
ribs, and the manubrium of the sternum. Its inferior margin curves down-
wards and backwards on each side from the ensiform process to the twelfth
Fig. 23.
Fig. 23. FRONT VIEW OF THE THORAX,
SHOWING THE STERNUM COSTAL CARTI-
LAGES, RIBS, AND DORSAL VERTEBRA, i
1, the manubrium, or first piece of the
sternum ; 2, is close to the place of union
of the first costal cartilage ; 3, the clavicular
notch ; 4, the middle of the body of the
sternum ; 5, the ensiform piece ; 6, the
groove on the lower border of the ribs ; 7,
the vertebral end of the ribs ; 8, the neck ;
9, tubercle; 10, costal cartilage; 12, the
first rib; 13, its tuberosity; 14, the first
dorsal vertebra ; 15, the eleventh ; 16, the
twelfth rib.
rib. Its longitudinal axis is directed
upwards and slightly backwards. Its
transverse diameter, at its widest part,
greatly exceeds that from before back-
wards. The latter is shortened in
the middle line by the projection of
the vertebral column, but on each
side of the column a considerable ex-
tension of the cavity is produced by the backward direction of the posterior
parts of the ribs, and thus the weight of the body is thrown further back
and more equally distributed round the vertebral column. At the same
time a broad furrow is produced between the spines of the vertebrae and the
angles of the ribs, in which are placed the erectores spinse muscles.
DEVELOPMENT OF THE RIBS AND STERNUM.
The first origin of the posterior parts of the ribs in connection with the
primordial vertebrae has been already mentioned. In the second month
cartilage appears in them, deposited independently of the vertebrae.
Different opinions have been held as to whether the tubercle or the head
of the rib is the primary point of its connection with the vertebra : it appears
probable that the whole extent from head to tubercle is an expansion of the
original connection. (Kolliker, "Entwicklungsgeschichte," fig. 81 ; Rathke,
"Entwick. der Natter;" Huxley, "On the Theory of the Vertebrate Skull,"
p. 74.) After becoming cartilaginous, the ribs pass round in the visceral
wall, and, according to Rathke, before reaching the front, the first seven on
28
BONES OF THE THORAX.
each side are united together at their anterior extremities in two longitudinal
strips of cartilage, which afterwards join together in the middle line to
form the sternum.
Fig. 24.
Fig. 24. OSSIFICATION OF THE STERNUM.
A, the cartilaginous sternum before the middle of foetal life.
B, the sternum of a child at birth. 1, 2, 3, & 4, mark the commencing ossific nuclei
for the manubrium and three upper pieces of the body.
C, the sternum soon after puberty, showing cartilage between the manubrium and
body, and imperfect union of the first, second, and third pieces of the body, while the
third and fourth are united.
D, shows an example of a sternum at birth with an unusual number of ossific
centres, six in the manubrium, 1', which is very uncommon ; two pairs in the lower
pieces of the body, 3' & 4', which is not unusual ; 2, the single centre of the first piece of
the body.
E, exhibits an example of the perforated sternum which probably depends upon the
imperfect union of the pairs of ossific nuclei shown in D in the lower part of the body ;
this figure also shows two episternat bones or granules, * *.
Ossification. Each of the ribs is ossified from one principal centre, and
possesses two small epiphyses, one belonging to the head, and, except in
the last two ribs, another belonging to the tubercle.
The sternum is ossified in a number of separate pieces, one, at least, for
each segment ; the manubrium sometimes possesses two, placed one above
Fig. 25. ONE OF THE
MIDDLE RIBS OF A
PERSON ABOUT EIGH-
TEEN OR TWENTY
YEARS OF AGE.
Showing, at 1, the
principal piece or body;
2, the epiphysis of the
head ; 3, that of the
tubercle.
the other, and has
been found with a
greaternumber. The
third, fourth, and
fifth segments, as well as the ensiform portion, are frequently formed
each from two nuclei placed side by side, which may remain distinct for
SKULL. OCCIPITAL BONE. 29
a considerable time ; the second segment has rarely more than one
nucleus. Additional nuclei occasionally appear between some of the
segments.
PERIODS OF OSSIFICATION OF THE RIBS AND STERNUM.
Ill the ribs
The principal centres appear in the 7th or 8th week (foetal life).
The epiphyses appear from the 16th to the 20th year.
The shaft and epiphyses unite about the 25th year.
In the sternum
Ossification in the first segment appears in the 6th or 7th month (foetal life).
Ossification in the second segment appears in the 7th or 8th month (foatal life).
Ossification in the third and fourth segments appears shortly before birth.
Ossification in the fifth segments appears in the 1st year or later.
Ossification in the sixth or ensiform segment appears very variously from the 6th
to the 1 5th year, or later.
The lower segments of the body unite after puberty.
The upper segments of the body unite from the 25th to the 30th year.
The body and ensiform segment generally unite in middle age.
The manubrium and body unite in old age.
III. THE BONES OF THE SKULL.
The skull is of a spheroidal figure, compressed on the sides, broader
behind than before, and supported on the vertebral column. It is formed of
a number of bones, all of which, with the exception of the lower jaw, are
almost immovably united together by lines and narrow surfaces, more or less
uneven, termed sutures. The skull is divided by anatomists into two parts,
the cranium and the face. The cranium protects the brain ; the face
surrounds the mouth and nasal passages, and completes with the cranium the
cavities for the eyes. The cranium is composed of eight bones, viz. : the
occipital, two parietal, the frontal, two temporal, the sphenoid, and the
ethmoid. The face is composed of fourteen bones, of which twelve are in
pairs, viz. : the superior maxillary, malar, nasal, palate, lachrymal, and
inferior turbinated bones ; and two single, viz., the vomer, and the inferior
maxilla.
THE OCCIPJTAL BONE.
The occipital bone is situated at the lower and back part of the cranium.
Its general form is that of a curved lozenge concave superiorly, through
which, in its lower and anterior part, passes a large oval foramen, form-
ing the communication between the cranium and spinal canal. The bone
thus presents four borders and four angles, which receive names according
to their position. The portion of the bone behind the foramen is tabular,
that in front of the foramen forms a thick mass named basilar process, and
the parts on the sides of the foramen, bearing the condyles or articulating
processes by which the head is supported on the first vertebra, are dis-
tinguished as the condyloid portions.
The occipital bone articulates by its two superior borders with the parietal
bones, and by its two inferior borders with the temporal bones, while the
extremity of its basilar process is united to the body of the sphenoid, in the
young condition by cartilage, but after the age of twenty years by con-
tinuous osseous* substance.
* Hence Soemmerring described the occipital and sphenoid as a single bone under the
name spheno-occipital, or basilar.
30
BONES OF THE HEAD.
The TABULAR PORTION on its posterior surface presents a rough prominence,
the external occipital protuberance, arching outwards from which, on each side,
Fig. 26. OCCIPITAL BONE
FROM BELOW AND BEHIND,
SHOWING THE EXTERNAL
SURFACE. 4
1, basilar process ; 2, con-
dyloid portion, the probe
marks the anterior condyloid
foramen; 3, jugular or trans-
verse process ; 4, external or
lateral angle ; 5, superior
angle ; 6, superior curved line ;
7, external or posterior occi-
pital protuberance ; 7, 8, ex-
ternal occipital crest ; 9, in-
ferior curved line ; 10, groove
and ridge connected with the
attachment of the superior
oblique muscle, and near it
the inferior opening of the pos-
terior condyloid foramen ; 11,
foramen magnum ; 12, arti-
cular condyle ; immediately
above it the posterior condy-
loid foramen.
is the superior occipital
ridge or curved line,, which
divides the surface into two
parts, the upper, covered by the hairy scalp, convex and uniform ; the lower,
uneven and marked by the impressions of the muscles of the neck which are
Fig. 27. OCCIPITAL BONE
FROM BEFORE, SHOWING THE
INTERNAL SURFACE. \
1, basilar process sawn
through at the place of union
with the sphenoid bone ; 2,
condyloid portion ; 3, jugular
or transverse process ; x , be-
tween 2 & 3, the sigmoid
groove of the lateral sinus and
jugular notch ; 4, external or
lateral angle ; 5, superior
angle; 1 to 3, the edge of
articulation with the petrous
bone ; 3 to 4, with the mas-
toid bone ; 4 to 5, with the
parietal bone ; 11, foramen
magnum; 13, internal occipi-
tal protuberance and groove of
the torcular Herophili ; 14, in-
ferior spine ; 15, groove of the
lateral sinus ; from 5 to 13,
groove of the superior longi-
tudinal sinus ; 16, cerebral
fossa; 17, cerebellar fossa.
attached to it. This lower
surface is divided into two lateral portions by a median ridge called the ex-
ternal occipital crest or spine, and each of these portions is again divided into
OCCIPITAL BONE. 31
an upper and a lower surface by the inferior curved line or ridge, which,
after extending some distance outwards, is met by a ridge and groove passing
from before backwards. These surfaces mark the attachments of the rectus
capitis major and minor, and of the obliquus capitia superior muscles.
The deep surface of the bone is marked by two crucial smooth ridges, one
extending from the upper angle to the great foramen, and the other trans-
versely from one lateral angle to the other, and at the point of intersection
of these ridges is the internal occipital protuberance. Separated by these
ridges are four hollows, the superior and inferior occipital fossae, which lodge
respectively the posterior cerebral and the cerebellar lobes. The superior and
transverse ridges are grooved in the course of the longitudinal and lateral
venous^ sinuses respectively. The space where those grooves meet at the in-
ternal occipital protuberance receives the torcular Herophili. The inferior
ridge is single, and is named the internal occipital crest or spine. The
margins of the tabular portion are deeply serrated above the lateral angles
for articulation with the parietal bones, and, below that level, with the
mastoid portions of the temporal bones.
The CONDYLOID PORTIONS bear the articulating condyles on their inferior
surface, close to the margin of the foramen magnum. The condyles are so
placed, that a line touching their posterior extremities would cross the
middle of the foramen magnum. They are elliptical and placed obliquely
so as to converge in front ; their surfaces are convex from behind forwards
and from side to side, and slightly everted. Their inner borders are
rough, and receive the insertion of the odontoid ligaments of the axis.
In front and to the inside of the condyles are the anterior condyloid
foramina, which pass forwards and outwards from the interior of .the
cranium, and transmit the hypoglossal nerves. Behind the condyles are
two pits, containing usually the posterior condyloid foramina ; each of
these gives passage to a vein ; but they are often absent on one or both
sides. Externally to the coudyle, on each side, is a portion of bone,
which is placed over the transverse process of the atlas, continuous pos-
teriorly with the tabular part, and anteriorly having a free excavated
margin, the jugular notch, which contributes with a fossa in the temporal
bone to form the foramen lacerum jugulare ; its external extremity pro-
jects into the angle between the mastoid and petrous portions of the
temporal bone, and is called the jugular eminence. This process presents
inferiorly a rough elevation, which gives attachment to the rectus capitis
lateralis muscle ; and superiorly a deep groove for the lateral sinus before
it terminates in the jugular notch.
The BASILAR PROCESS projects forwards and upwards into the middle of
the base of the skull. It increases in thickness and diminishes in breadth
towards its extremity. Inferiorly it gives attachment to the rectus capitis
anticus major and minor muscles and the fibrous band of the pharynx. Its
superior surface presents a smooth depression, the basilar groove, which
supports the medulla oblongata, and close to each lateral margin a slight
grooved mark, which indicates the place of the inferior petrosal sinus.
Varieties. The upper and lateral angles vary greatly in the degree of their acute-
ness. The upper borders are subject to considerable variation, from the presence
of ossa triquetra. The condyles vary greatly in size, prominence, and convexity,
and are often somewhat unsymmetrical. In some old subjects there is a mark at the
back of the foramen magnum, where the occiput rests on the posterior arch of the atlas.
Occasionally there is a projection downwards from the jugular process, resembling
the descending lateral process found in most mammals.
HONES OF THE HEAD.
THE PARIETAL BONE.
The parietal bones form a principal part of the roof of the skull. They
have the shape of quadrilateral plates, ccnvex externally, concave internally.
They are a little broader above than below, and the anterior inferior angle
is the most acute. They articulate with one another in the middle line,
with the frontal bone anteriorly, the occipital posteriorly, and the temporal
and sphenoid below.
Fig. 28.
Fig. 23. EXTERNAL SURFACE OP
THE RIGHT PARIETAL BoNE. |
1, posterior superior angle ;
2, anterior superior angle ; 3,
posterior inferior angle ; 4, ante-
rior inferior angle ; from 1 to 2,
superior border in the sagittal
suture ; from 2 to 4, anterior
border in the coronal suture ;
from 1 to 3, posterior border in
the lambdoidal suture ; from
4 to 6, the part of the inferior
border in the squamous suture ;
from 3 to 6, the part in the ad-
ditamentum suturas squamof-ae ;
5, the temporal or semicircular
line above which is the parietal
eminence.
On the outer surface, the
point of greatest convexity
is called the parietal emi-
nence. Below this a curved
line is directed from the
anterior to the lower part of the posterior margin ; it is the parietal part
of the temporal ridge, and bounds a surface somewhat flatter than the rest,
planum temporale t which
* forms part of the tempo-
ral fossa. Near the pos-
terior and upper angle,
close to the middle line,
there is often a small
perforation of variable
dimensions, the parietal
foramen, which trans-
mits a communicating
vein.
Fig. 29. THE PARIETAL
BONE FROM THE INSIDE.
1, 2, 3, 4, & 6 indicate
the same parts as in the last
figure : between 1 & 2 the
half groove of the superior
longitudinal sinus ; 7, the
ramified grooves of the
meningeal vessels ; at x this
groove is converted into a
THE FRONTAL BONE.
33
canal, and throughout the inner surface the dimpling of the convolutions of the cerebrum ;
8, the parietal foramen ; 9, the irregular pits for the gland ulse Pacchionii.
On the inner surface, the hollow corresponding to the eminence is called
the parietal fossa. This surface is marked by grooves branching upwards and
backwards, corresponding with the course of the middle meningeal vessels,
and by depressions corresponding with the convolutions of the brain. A
slight depression along the superior border completes with the one of the
opposite side a groove marking the course of the longitudinal sinus ; and a
depression at the posterior inferior angle forms a small part of the groove
of the lateral sinus. Near the upper border there are in most skulls, but
particularly in those of old persons, small irregular pits, fovece glandular es,
the result of absorption produced by the so-named glandulae Pacchionii.
Borders. The anterior, superior, and posterior borders are serrated. The
inferior border presents in the greater part of its extent a sharp or squa-
mous edge, with a slightly fluted surface directed outwards and overlapped at
its anterior extremity by the great wing of the sphenoid, and behind that
by the squamous part of the temporal bone ; but at its posterior part it is
serrated, and articulates with the mastoid portion of the temporal. The
posterior border is the most deeply serrated. The anterior border is slightly
overlapped by the frontal bone above, but overlaps the edge of that bone
inferiorly.
THE FRONTAL BONE.
The frontal bone, arching upwards and backwards from above the orbits,
forms the fore part of the vault of the skull. It likewise presents inferiorly
two thin horizontal laminse, the orbital plates, which form the roofs of the
orbits and are separated by a mesial excavation, the incisura ethmoidalis.
Fig. 30. FRONTAL BONE FROM
BEFORE, SHOWING ITS EXTER-
NAL SURFACE.
1, frontal protuberance ; 2,
nasal spine, and above this the
serrated surface for articulation
of the nasal and superior maxil-
lary bones ; 3 to 4, supra-orbital
edge 3, internal, and 4, exter-
nal angular process ; 5, supra-
orbital notch or foramen; 6,
glabella; 7, superciliary emin-
ence and ridge ; 8, temporal
ridge, and behind this a part of
the temporal fossa.
The frontal is articulated
with twelve bones, viz.,
posteriorly with the parie-
tals and sphenoid ; outside
the orbits with the malars ;
and between the orbits,
from before backwards, with
the nasal, superior maxillary, lachrymal and ethmoid bones.
Anterior Surface. The part forming the greatest convexity of the fore-
head on each side is called the frontal eminence. It is separated by a
slight depression below from the superciliary ridge, a curved elevation of
34
BONES OF THE HEAD.
varying prominence immediately above the margin of the orbit. Between
the superciliary ridges is the nasal eminence or gldbella. The margin of the
orbit, the orbital arch, is most defined towards its outer part j it presents
towards its inner third the supra-orbital notch, sometimes converted into a
foramen, which transmits the supra-orbital nerve and artery. The ex-
tremities of the orbital arch point downwards, and form the internal and
external angular processes. The internal angular process is slender ; the
external is thick and strong, and articulates with the malar bone. The
temporal ridge springs from the external aspect of this process, and
arches upwards and backwards to be continued on the parietal bone : it
separates the temporal from the frontal part of the outer surface of the
bone.
Inferior Surface. The orbital surfaces are somewhat triangular, their
internal margins being parallel, while the external are directed backwards
and inwards. Close to the external angular process is the fossa lachry-
malis, which lodges the lachrymal gland ; and close to the internal angular
process is the fovea trochlearis, a small depression to which the pulley of the
trochlearis muscle is attached. Between the orbits in front is the serrated
surface which articulates with the superior maxillary and nasal bones, and in
the middle line a sharp process of variable length, the nasal spine, descends
between the latter bones and the central plate of the ethmoid. On the
sides of the incisura ethmoidalis, the inner table of the bone extends nearer
the middle line than the outer, and the intervening margin is thrown
into shallow spaces, which form the roofs of cells in the ethmoid bone.
Traversing this margin are two grooves, which complete, with the eth-
moid, the anterior and posterior internal orbital foramina. The ante-
rior groove transmits the nasal twig of the ophthalmic nerve and the
anterior ethmoidal vessels ; the other, the posterior ethmoidal vessels.
Further forward, on each side of the nasal spine, is a larger hollow,
the opening of the frontal
Fig. 31. sinus, which extends for a
variable distance behind the
superciliary ridges, and which
communicates with the cavity
of the nose . Outside the orbi-
tal surface behind the serrated
border for the malar bone,
there is a large serrated tri-
angular area which articulates
with the great wing of the
sphenoid.
Fig. 31. THE FRONTAL BONE
FROM BEHIND AND BELOW,
SHOWING THE INTERNAL CERE-
BRAL SURFACE AND THE ROOF
OF THE ORBITS. 4
2, 4, and 5, as in the preceding
figure; 9, internal or cerebral
surface, slightly marked by cere-
bral convolutions and glandular
pits; 10, groove of the superior
longitudinal sinus, ending below
in, 11, the internal frontal crest, which leads down to, 13, the foramen caecum; 12, the
orbital plate, the number is placed in the depression for the lachrymal gland; 14, the
THE TEMPORAL BONE.
35
opening of the frontal sinus ; 15, placed near the inside of the roof of the orbit indicates
the inner ends of the ethmoidal or internal orbital foramina.
Cerebral Surface. This surface forms a large concavity, but the roofs
of the orbital plates, which form its floor, are convex from side to side.
It is covered with digitate impressions, which, with the intervening ridges,
are strongly marked over the orbits. A groove, the sulcus frontalis, which
lodges the commencement of the longitudinal sinus, ascends in the middle
of the upper part of the bone ; its margins approach inferiorly, and are
elevated into a ridge, the crista frontalis. A small foramen, usually formed
in part by the central plate of the ethmoid, is situated at its base ; it is
known as the foramen ccecum, but transmits a minute vein from the nasal
fossae. This surface is bounded posteriorly by a thin linear border, which
articulates with the lesser wings of the sphenoid, and superiorly and
laterally by a serrated border, which articulates with the parietals, and
which, as has before been mentioned, slightly overlaps those bones above,
and is overlapped by them at the sides.
THE TEMPORAL BONE.
The temporal bone (os temporis) takes part in the construction of the
sifle and base of the skull, and contains in its interior the organ of hearing.
It is usually described in three parts, viz., an expanded anterior and superior
part the squamous portion, a much thicker posterior portion the mastoid,
and below and between these the petrous portion, a three-sided pyramid
exhibiting at its base externally the aperture of the ear and projecting
forwards and inwards into the base of the skull.
It articulates posteriorly and internally with the occipital bone, superiorly
with the parietal, anteriorly with the sphenoid by the zygomatic process
with the malar, and by the glenoid cavity with the inferior maxillary bone.
"$he SQUAMOUS PORTION extends forwards and upwards from its connection
with the other portions, and presents superiorly an arched border which
describes about two-thirds of a circle.
Fi*. 32.
Fig. 32. RIGHT TEMPO-
RAL BONE FROM THE
OUTSIDE. |
1, the external surface
of the squamous part ; 2,
the zygoma ; 3, the mas-
toid part ; 3 x , the mas-
toid process ; 4, the arti-
cular part of the glenoid
fossa ; 5, the articular
eminence at the root of the
zygoma, and above it the
tubercle ; 6, fissure of
Glaser ; 7, the tympanic
plate forming the posterior
non -articular part of the
glenoid fossa, terminating
behind in the vaginal pro-
cess ; 8, the meatus audi-
torius externus ; 9, the 10
auditory process ; 10, the
Btyloid process ; 13 x , the
mastoid foramen.
The inner surface is marked by cerebral impressions, and by meningeal
grooves. At its npper border, the outer table is prolonged considerably
36
BONES OF THE HEAD.
beyond the inner, forming a thin scale with the rough surface looking
inwards and overlapping the corresponding bevelled edge of the parietal
bone. But in front the border is thicker, looks directly forwards, and is
serrated for articulation with the great wing of the sphenoid boue.
The outer surface is in its greatest extent vertical, with a slight con-
vexity, and formj part of the temporal fossa. From its lowest part a long
process, the zygoma, takes origin.
The zygoma, or zygomatic process, is at its base of considerable breadth,
and projects outwards. It then becomes narrower, and is twisted on itself
so as to present an outer and inner surface, and a sharp upper and lower
border. The superior margin is the thinnest, and is prolonged furthest
forwards. The bevelled extremity is serrated, and articulates with the malar
bone. At its base the zygomatic process presents two roots. The anterior
root is a broad convex ridge, directed inwards. The posterior root passes
backwards, and is divided into two parts, of which one turns inwards in
front of the meatus externus, while the other, gradually subsiding, ia
continued backwards over that opening, and marks behind it the line of
union of the squamous and mastoid portions of the bone. At the point of.
division of the two roots is a slight tubercle, which gives attachment to
the external lateral ligament of the lower jaw. Between them is the glenoid
fossa, a depression elongated from without inwards, and which, together with
a cylindrical elevation on the anterior root of the zygoma in front of it,
is coated with cartilage, and forms the articular surface for the joint with
the lower jaw. The fissure of Glaser separates this articular part of the
glenoid fossa from the remaining part behind, which is formed by the
tympanic plate of the petrous division of the temporal bone and lodges a
portion of the parotid gland.
Fig. 33.
Fig. 33. THE RIGHT TEM-
PORAL BONE PROM THE
INNER SIDE. |
The indications where
marked are the same as in
the preceding figure. 11, the
inner or cerebral surface of
the squamous portion ; 11 x ,
the squamous edge ; 12, inner
surface of the mastoid por-
tion ; 13, the sigmoid groove
of the lateral sinus the
figure is placed at its upper
part, and close to the mastoid
foramen ; 14, the apex of the
petrous bone; 15, the meatus
auditorius internus; 16, the
scale of bone covering the
aqueduct of the vestibule;
17, is above the aqueduct of
the cochlea ; 18, the superior
petrosal groove ; 19, the
eminence of the superior
semicircular canal; 20, the
hiatus Fallopii.
The MASTOID POUTION is rough externally for the attachment of muscles,
and is prolonged downwards behind the aperture of the ear into a nipple-
sliaped projection the mastoid process. This process has on its inner side
a deep groove, the digastric fossa t which gives attachment to the digastric
3*
THE TEMPORAL BOXE.
37
muscle ; and internal to that is the slight occipital groove, for the occipital
artery. The internal surface of the mastoid portion is marked by a deep
sigmoid depression, descending in the angle between it and the petrous
portion, which is part of the groove of the lateral sinus. A passage for a
vein, of very variable size, the mastoid foramen, usually pierces ths bone
near its posterior margin, and opens into the groove.
Fig. 34.
Fig. 34. THE RIGHT TEMPORAL BONE FROM
BELOW. |
The indications where marked are the same
as in the preceding figures. 14, is at the apex
of the petrous bone in the upper opening of the
carotid canal; 17, aqueduct of the cochlea;
21, lower rough surface of the petrous bone ;
22, the lower opening of the carotid canal ;
23, the small foramen of Jacobson's nerve ;
24, the jugular depression, and within it, 25,
the foramen of Arnold's nerve ; 26, stylo-mas-
toid foramen the figure is placed in the ante-
rior part of the digastric groove ; 27, groove of
the occipital artery ; 28, place of the anterior
opening of the osseous Eustachian canal.
The PETROUS PORTION is named from
its hardness. It contains the organ of
hearing. It forms a three-sided pyra-
mid, with its base directed outwards,
one surface looking downwards, and
the other two turned towards the interior of the skull.
Inferior surface, base and apex. At the base is the aperture of the ear.
It forms a short canal, the meatus auditorius externus, directed inwards
and a little forwards, narrower in the middle than at its extremities, and
leading into the cavity of the tympanum. It is bounded superiorly by
the posterior root of the zygoma, and posteriorly in the remainder of its
circumference chiefly by the external auditory process, a curved uneven
border, to which the cartilage of the ear is attached. This process is the
thickened outer extremity of the tympanic plate, a lamina one surface of
which forms the anterior wall of the external auditory meatus and the tym-
panum, while the other looks forwards and downwards. The anterior margin
of the tympanic plate is separated from the glenoid fossa by the fissure ofGlaser,
which communicates with the tympanum, while its posterior margin descends
as a sharp edge, the vaginal process, which partly surrounds the front of the
styloid process at its base. The styloid process is long and tapering, and is
directed downwards and forwards. It is placed in front of the digastric fossa,
and has immediately behind it the foramen which forms the outlet of the
canal of the facial nerve, named stylo-mastoid from its position between the
styloid and mastoid processes. A smooth rounded and deep depression,
the jugular fossa, lies internal to the styloid process ; it is close to the pos-
terior margin of the bone, and completes with the jugular notch of the occipital
bone the foramen lacerum posterius. In front and a little to the inside of
the jugular fossa is the carotid foramen, the inferior extremity of the carotid
canal ; and internal to the carotid foramen is a rough surface which gives
attachment to the levator palati muscle, and is continued into the rough
inner extremity, or apex of the petrous bone. The carotid canal ascends,
at first perpendicularly, then turns horizontally forwards and inwards, and
38 BONES OF THE HEAD.
emerges at the apex, close to the anterior margin. It transmits the internal
carotid artery. In the angle between the petrous and squamous portions
of the bone is the anterior opening of the Eustachian canal.
The posterior surface looks backwards and inwards, and forms part of
the posterior fossa in the base of the skull. It presents a large orifice
leading into a short canal which is directed outwards, the meatus auditorius
internus. This canal is terminated by a lamella of bone, the lamina cribrosa,
presenting in the lower part small apertures through which the fibrils of the
auditory nerve pass, while in its upper part is the commencement of the
caual called aqueduct of Fallopius, which transmits the facial nerve. The
facial canal takes a somewhat circuitous course through the petrous bone,
passing outwards and backwards over the labyrinth of the ear, and then
downwards to terminate at the stylo-mastoid foramen.
The anterior or upper surface looks upwards and forwards, and forms
part of the middle fossa in the base of the skull. A depression over the
apex marks the position of the Gasserian ganglion. A narrow groove runs
obliquely backwards and outwards to a foramen named the hiatus Fallopii,
which leads to the aqueduct of Fallopius ; and lodges the large superficial
petrosal nerve. Farther back is a rounded eminence, indicating the situa-
tion of the superior semicircular canal.
The superior border is grooved for the superior petrosal sinus. The
anterior border is very short, and forms at its junction with the squamous
part an angle in which is situated the orifice of the Eustachian canal, the
osseous portion of a tube of the same name, which leads from the pharynx
to the tympanum ; and above this, partially separated from it by a thin
lamella, the processus cochleariformis, a small passage which lodges the tensor
tympani muscle. The posterior border articulates with the basilar process
of the occipital bone, and bounds the foramen lacerum posterius.
Small foramina. The opening of the aqueductus vestibuli is a narrow fissure,
covered by a depressed scale of bone, and situated on the posterior surface of the
petrous bone, about three lines behind the internal auditory meatus; that of the
aqueductus cochleae, is a small foramen, beginning in a three-sided wider depression
in the posterior margin, directly below the internal auditory meatus. In the plate
between the jugular fossa and the carotid canal is the foramen by which the nerve of
Jacobson passes to the tympanum. In the ascending part of the carotid canal is the
minute foramen for the tympanic branch of the carotid plexus. In the jugular fossa
are a groove and foramen for the auricular branch of the vagus nerve ; and parallel
to the hiatus Fallopii, close to the canal for the tensor tympani muscle, are a groove
and foramen for the small superficial petrosal nerve.
THE SPHENOID BONE.
The sphenoid, or wedge-shaped bone, is placed across the base of the skull,
near its middle. It enters into the formation of the cavity of the cranium,
the orbits, and the posterior nares. It is of very irregular shape, and consists
of a central part or body, a pair of lateral expansions called the great wings,
which form the largest part of the bone, a pair of much smaller horizontal
processes in front, called the small wings, and a pair which project down-
wards, the pterygoid processes.
The sphenoid is articulated with all the seven other bones of the cranium
and with five of those of the face, viz., posteriorly with the occipital and
with the petrous portions of the temporals, anteriorly with the ethmoid,
frontal, and malars, laterally with the squamous portion of the temporals,
the parietals and frontals, and inferiorly with the vomer and palate bones.
THE SPHEXOID BONE.
39
The BODY. The superior surface presents in the middle a deep pit, the
pituitary fossa, sella turcica, or ephippium, which lodges the pituitary body.
In front of the fossa, separated from it by a shallow transverse groove, is
a narrow portion of bone on a level with the optic foramina, the olivary
process, on which rests the commissure of the optic nerves ; and in front of
this is a surface on a slightly higher level, continuous with the superior
surfaces of the small wings, and having a slight projection forwards of its
anterior border, which articulates with the cribriform plate of the ethmoid,
and is called the ethmoidal spine. Behind the pituitary fossa is a prominent
lamella, the dorsum sellce, the posterior surface of which is sloped upwards
and forwards in continuation of the basilar groove of the occipital bone.
The angles of this lamella project over the fossa, and are called the posterior
clinoid processes. On each side of the body the surface descends obliquely
to a considerably lower level than the fossa ; it presents close to the margin
of the fossa a superficial curved groove directed from behind forwards, marking
the course of the internal carotid artery.
Fig. 35.
JO
Fig. 35. THE SPHENOID BONE FROM ABOVE AND BEHIND.
1, the basilar surface, sawn separate from the occipital bone ; 2, dorsum sellae, or
inclined surface of the body terminating superiorly in the two posterior clinoid processes ;
3, is placed on the olivary eminence or process, and between it and 2 is the sella turcica,
or pituitary fossa ; in front of 3 is the transverse groove of the optic commissure ; 4, the
side of the body with the sigmoid groove of the internal carotid artery and cavernous
sinus ; 5, the lesser wings ; x , the anterior clinoid process ; 6, the ethmoid spine ; ?,
the cerebral surface of the greater wings ; 8, the upper angle of the great wings, which
articulates with the parietal bone ; 9, the spinous process ; 10, the external, and 11, the
internal pterygoid process; 11, is placed opposite the hamular process and groove for the
tendon of the tensor palati muscle ; 12, the optic foramen; 13, the sphenoidal fissure or
foramen lacerum orbitale ; 14, the foramen rotundum ; 15, the foramen ovale ; 16, the
foramen spinosum ; 17, is placed above the posterior opening of" the pterygoid or Vidian
foramen.
The posterior surface is flat, and united to the basilar process of the
occipital bone, in early life by cartilage, but in adult age by continuous
bony substance.
Anterior and inferior surfaces. Posteriorly, the body of the sphenoid
is solid, but anteriorly and inferiorly it contains two large cavities, the
sphenoidal sinuses, separated by a thin mesial lamina, the sphenoidal septum,
and covered in front and below by the sphenoidal spongy bones. A promi-
nent spine, called the rostrum, formed partly by the septum, partly by the
40 BONES OF THE HEAD.
spongy bones, dips forwards and downwards, and is connected with the
vomer. A thin edge, the sphenoidal crest, extends from the rostrum to the
ethmoidal spine, and articulates with the central plate of the ethmoid.
The sphenoidal spongy bones, cornua sphenoidalia, or bones of Bertin, are
a pair of thin curved plates, whose closest anatomical relationship in the
adult is with the sphenoid bone, but which are originally distinct, and are
frequently united by earlier or stronger anchylosis with the ethmoid or
palate bones, so as to adhere, at least in part, to either of these in dis-
articulation of the skull, and thus to lay open the sinuses of the sphenoid.
The anterior part of each looks forwards, and leaves a considerable round
opening by which the sinus communicates with the nasal cavity ; the lower
and posterior part is of a triangular form, with the apex directed backwards.
At the anterior and outer angle of the sphenoidal spongy bone is a small part
which enters into the formation of the inner wall of the orbit, articulating in front
with the ethmoid, behind with the sphenoid, above by a small angle with the frontal,
and below with the orbital process of the palate bone. It is most frequently fused in
the adult with the sphenoid or ethmoid, often, however, with the palate bone only,
and sometimes it remains free. (See Cleland in Trans, of Roy. Soc. for 1862.)
The GREAT WINGS, alee majores, project outwards and upwards from the
sides of the body. The lower and back part of each, horizontal in direction,
occupies the angle between the petrous and squamous portions of the temporal
bone ; from its pointed extremity it sends downwards a short and sharp
projection, the spinous process. The upper and fore part is vertical, and
three-sided, lying between the cranial cavity, the orbit, and the temporal
fossa. The cerebral surface of the great wing is concave, and forms part of
the middle fossa of the base of the cranium. The external surface (temporo-
zygomatic) is divided by a ridge into an inferior part, which looks down-
wards into the zygomatic fossa, and an elongated superior part, looking
outwards, which forms a part of the temporal fossa. The anterior surface
looks forwards and inwards, and consists of a quadrilateral orbital portion,
which forms the back part of the external wall of the orbit, and of a smaller
inferior portion which overhangs the pterygoid process, looks into the spheno-
maxillary fossa, and is perforated by the foramen rotundum. Posteriorly,
the cerebral and external surfaces are separated by the margins which
articulate with the temporal and parietal bones ; anteriorly, the superior
divisions of the external and anterior surfaces are separated by the margin
which articulates with the malar bone, while their inferior divisions come into
contact with each other, and form the upper part of the posterior boundary
of the pterygo-maxillary fissure ; internally, the cerebral and orbital surfaces"
come into contact at the outer border of the sphenoidal fissure ; and
superiorly, all three surfaces abut against the triangular area which articu-
lates with the frontal bone.
The SMALL WINGS, alee minores, or wings of Ingrassias, extend nearly
horizontally outwards from the fore part of the superior surface of the body.
The extremity of each is slender and pointed, and comes very close to, but
not into actual contact with, the great wing. The superior surface forms
part of the anterior fossa of the base of the cranium, the inferior overhangs
the sphenoidal fissure and the back of the orbit. The anterior border, thin
and serrated, passes directly outwards, and articulates with the orbital plate
of the frontal bone. The posterior border is prominent and free, and forms
the boundary between the anterior and middle cranial fossae : it is pierced
at its base by the optic foramen, and immediately beyond that projects
THE SPHENOID BONE. 41
backwards, making a smooth rounded knob, the anterior clinoid process,
which inclines towards the posterior process of the same name, and is
grooved on its inner margin for the internal carotid artery.
The PTERYGOID PROCESSES project downwards and slightly forwards,
between the body and the great wings. Each consists of two plates united
in front and diverging behind, so as to enclose between them the pterygoid
fossa. The external pterygoid plate lies in a plane extending backwards and
outwards ; its outer surface bounds the zygomatic fossa, and gives attach-
ment to the external pterygoid muscle. The internal pterygoid plate is
longer and narrower than the external, and is prolonged into a slender
process turned outwards and named the hook-like or hamular process, round
which in a groove plays the tendon of the tensor palati muscle. At its base,
the internal plate turns inwards beneath the body, from which its extremity
remains distinct as a slightly raised edge, which articulates with the margin
of the vomer ; and externally to this it is marked by a small groove, which
contributes with the palate bone to form the pterygo-palatine canal. The
walls of the pterygoid fossa are incomplete at the lower part in the dis-
articulated sphenoid bone, an angular interstice existing between the plates,
which, in the articulated skull, is occupied by the pyramidal process of the
palate bone. In this fossa arises the internal pterygoid muscle, and at its
base is a slight depression, distinguished as the navicular fossa, which gives
attachment to the tensor palati muscle.
Fig. 36.
Fig. 36. THE SPHENOID BONK FROM BEFORE. f
The indications where marked are the same as in the preceding figure. 17, marks the
anterior opening of the Vidian foramen or canal ; 18, the external or temporal surface of
the great wing; 19, its orbital surface; 20, the sphenoidal turbinated or spongy b one ;
above 20, the opening into the sphenoidal sinus ; 21, the sphenoidal spine ; 22, the
rostrum, and above 22, the inverted laminae, which fit with the edges of the vomer.
FISSURES AND FORAMINA. Each lateral half of the bone presents a
fissure, four foramina, and a canal. The sphenoidal fissure is the obliquely
placed elongated interval between the great and the small wing ; it is closed
externally by the frontal bone, so as to form the foramen lacerum orbitale ; it
opens into the orbit, and transmits the third, fourth, and sixth nerves, the
ophthalmic division of the fifth nerve, and the ophthalmic vein. Above and
to the inside of it is the optic foramen, which, is inclined outwards and
forwards from the side of the olivary process, pierces the base of the small
42
BO:N T ES OF THE HEAD.
wing, and transmits the optic nerve and the ophthalmic artery. The foramen
rotundum is directed forwards through the great wing, below the sphenoidal
fissure ; it opens immediately below the level of the orbit, and transmits the
superior maxillary division of the fifth nerve. The foramen ovale is a large
foramen, external and posterior to the foramen rotundum, situated near
the posterior margin of the great wing, and directed downwards ; it transmits
the inferior maxillary division of the fifth nerve. The foramen spinosum
is a small foramen immediately external and posterior to the foramen ovale ;
it pierces the posterior angle of the great wing, and transmits the middle
meningeal vessels.
The Vidian, or pteryyoid canal, passes through the bone horizontally
from before backwards at the base of the internal pterygoid plate ; it opens
anteriorly into the spheno-maxillary fossa, and posteriorly into the foramen
lacerum medium, and transmits the Vidian nerve and vessels.
Varieties. The groove of the internal carotid artery on the inner aspect of the
anterior clinoid process is frequently converted into a foramen by a spiculum of bone
stretching outwards to that process from the side of the pituitary fossa, and forming
what has been called the middle clinoid process ; and in cases where this occurs
another spiculum is sometimes found, uniting the anterior and posterior clinoid pro-
cesses. In many cases a third spiculum, the lingula (Henle), projects backwards from
the posterior extremity of the carotid groove outside the artery. A bridge of bone,
or of ligament, sometimes passes from the margin, and sometimes from the extremity
of the external pterygoid plate to the spinous process. The foramen ovale and foramen
spinosum are frequently open behind.
ETHMOID BONE.
The ethmoid, or sieve-like bone, projects down wards from between the orbital
plates of the frontal bone, and enters into the formation of the cranium, the
orbits, and the nasal fossae. It is of a cu-
boid figure. It is exceedingly light for its
size being composed of very thin plates
of bone and a collection of irregular
cells. It consists of a central vertical
plate, and of two lateral masses, united
at their superior extremities by a horizon-
tal cribriform lamella.
Fig. 37. THE ETHMOID BONE, f
A, from the right side. 1, crista galli ; 2,
vertical plate ; 3, cribriform plate and foramina ;
4, orbital plate or os planum ; 5 5, the uncinate
process ; 6, the superior, and 7, the inferior
turbinated bone ; 8, the anterior, and 9, the
posterior ethmoidal groove or foramen.
B, the ethmoid bone from behiud. The in-
dications where marked are the same as in A.
10, the lateral or cellular part of the bone ; 11,
its posterior surface of union with the sphenoidal
turbinated and palate bones.
It articulates with thirteen bones : the
frontal, sphenoid and vomer, the nasal,
lachrymal, superior maxillary, palatal, and inferior turbinated bones.
The CENTRAL PLATE lies in the mesial plane, and forms the upper part of
the septum of the nose. Its superior margin appears in the cranial cavity,
above the cribriform lamella, in the form of a ridge which rises anteriorly
into a thick process, the crista galli, to which the falx cerebri is attached.
i- 37.
THE ETHMOID BOXE. 43
The anterior margin of the crista galli is vertical and broad, usually pre-
senting a groove, which completes the foramen caecum of the frontal bone.
Below the level of the cribriform lamella, the anterior margin of the central
plate articulates with the nasal process of the frontal and with the nasal bones.
The inferior margin articulates in front, and sometimes even in its whole
extent, with the septal cartilage of the nose ; and in its posterior half, in the
adult, is more or less completely joined by osseous union on one or both
sides to the two plates or alae of the vomer. The posterior margin is very
thin, and is united to the sphenoidal crest of the sphenoid. This plate
presents a number of grooves and minute canals leading from the foramina
of the cribriform lamella, for the transmission of the olfactory nerves.
The LATERAL MASSES enclose a number of spaces of irregular form, the
ethmoidal cells, which in the recent state are lined with prolongations of the
mucous membrane of the nose. On the external aspect of each lateral mass
is a thin, smooth lamina, of a quadrilateral form, the orbital plate or os
planum, which closes in the ethmoidal cells, and forms a considerable part of
the inner wall of the orbit. The orbital plate articulates iu front with the
lachrymal, behind with the sphenoid, above with the frontal, and below with
the orbital surfaces of the superior maxillary and palate boues. In front of the
orbital plats the lateral mass extends forwards, under cover of the lachrymal
bone ; and from this part descends the uncinate or cuneiform process, a long
thin lamella which curves downwards, outwards, and backwards, forming
part of the inner wall of the maxillary antrum, and articulating at its
extremity with the inferior turbinated bone. (See fig. 50.)
The internal aspect of each lateral mass forms part of the external wall of
the nasal fossa, and consists of a thin, uneven, osseous plate, connected above
with the cribriform lamella, and exhibiting a number of canals and grooves
for branches of the olfactory nerve. It is divided at its back part by a channel,
directed upwards and forwards from its posterior margin to about its middle.
This is called the superior meatus of the nose, and communicates with the
posterior ethmoidal cells. The short margin which overhangs this channel
constitutes the superior turbinated process or spongy bone. Below this is a
slightly folded margin of much greater extent, and free in front, the inferior
turbinated process or middle spongy bone, which overhangs the middle meatus
of the nose. From the front of the middle meatus a passage, the infundi-
buhim, is prolonged upwards and forwards through the anterior ethmoidal
cells, and opens into the frontal sinus. (See also tig. 54.)
In the separate ethmoid bone the cells are open posteriorly and superiorly,
but when the bone is in connection with the rest of the cranium these cells
are closed, above by the frontal bone, and behind by the sphenoidal spongy
bones. In the superior margin are two grooves, which complete with the
frontal bone the internal orbital foramina.
The CRIBRIFORM LA.MELLA corresponds in size to the incisura ethmoidalis of
the frontal bone which it occupies. At the sides of the crista it is depressed
into two grooves which lodge the olfactory bulbs ; and it is pierced by
numerous foramina, for transmission of the filaments of the olfactory nerves.
The foramina, which lie along the middle of each groove, are simple perfora-
tions ; the internal and external sets are longer, and are the orifices of
small canals which subdivide as they descend on the central plate and
lateral masses. At the anterior extremity is a small fissure at each side of
the crista galli, close to its base, and externally to this a foramen, connected
usually by a slight groove with the anterior internal orbital foramen, which
transmits the nasal branch of the ophthalmic nerve.
44
BONES OF THE HEAD.
THE SUPERIOR MAXILLARY BONE.
This, the upper jaw, is one of the principal bones of the face ; it supports all
the teeth of the upper range, and takes part in the formation of the hard palate,
the floor of the orbit, and the floor and lateral wall of the nasal cavity. It
presents inferiorly a thick ridge, the alveolar process perforated with the
sockets for the roots of the teeth, and a horizontal palate plate ; exter-
nally, a convex surface corresponding with the anterior and lateral parts of
the face ; superiorly, an ascending or nasal process and an orbital plate ;
and internally, a nasal surface, opening from which is a large cavity or sinus,
hollowed out beneath the orbital plate in the body of the bone. The
superior maxillary bone articulates with its fellow, with the nasal, frontal,
lachrymal, ethmoid, palate, malar, vomer, and inferior turbinated bones, and
with the nasal cartilages.
Fig. 38.
Fig. 38. SUPERIOR MAXILLARY BONE OP THE
EIGHT SIDE. ^
A, from the outside; B, from the inside.
1 to 2, alveolar process or arch 1 at the
middle incisor tooth, 2 marks the tuberosity,
and above it, in A, the posterior dental foramina ;
3, the nasal or ascending process ; 4, malar
tuberosity or process ; 5, oi'bital plate or process ;
6, placed in the nasal notch marks the nasal crest
terminating in the nasal spine ; 7, the incisor or
myrtiform fossa ; 8, is in front of the canine fossa ;
9, the infra-orbital foramen, and below 5, the
infra-orbital groove and canal ; 10, groove of the
nasal or lachrymal duct; 11, antrum maxillare, or
maxillary sinus; 12, on the inner surface of the
nasal process, marks the oblique ridge for the
attachment of the inferior turbinated bone ; 13, is
placed above the palate plate ; from 13 to 6, the
vomeric and septal crest ; from 13 to 14, the
incisor foramen ; 15, placed on the surface of arti-
culation of the body with the palate bone, points
to the posterior palatine or palato-maxillary canal.
These figures also exhibit a full set of the upper
teeth of one side as they occur in middle life,
little worn by use.
The alveolar border or process, thick
and arched, is hollowed out into sockets
or alveoli, corresponding in number, form,
and depth to the roots of the teeth,
which are fixed in them.
The palate plate, along with that of the opposite side, forms about three-
fourths of the hard palate. Its superior surface is smooth and concave from
side to side ; its inferior surface is vaulted and rough, and is marked laterally
with grooves for nerves and vessels, which reach the palate through the
posterior palatine canal. Its posterior extremity falls short of that of the
alveolar arch and body of the bone, and articulates with the horizontal
process of the palate bone, which completes the hard palate. The mesial
border rises into a serrated vertical ridge, upon which the vomer rests.
This border, or ridge, is interrupted at its anterior part by a canal, the
incisor foramen, which is completed on its mesial side by a slender lamina
THE SUPERIOR MAXILLARY BONE. 45
directed backwards from the anterior to the posterior border, from the latter
of which, however, in young bones the lamina remains disconnected. In front
of this canal the mesial border of the bone rises to a considerably greater height
than behind it, forming, with its neighbour, the nasalcrest a grooved elevation
which supports the extremity of the vomer and the septal cartilage, and is pro-
longed forwards into the nasal spine. Each incisor foramen widens out below
into a larger hollow, which, when placed in apposition with its fellow, com-
pletes a mesial aperture, the anterior palatine foramen. Viewed from below,
this aperture may be seen to be divided into four smaller foramina, two of which
placed laterally are the incisor foramina, called also/oramma of Stenson, while
the other two, placed in the middle line, one before the other, are distinguished
as the foramina of Scar-pa. The whole communication between the nose and
the palate may be designated collectively as the anterior palatine canal.
The terms incisor foramen and anterior palatine canal are often used convertibly
and vaguely to express what has been above defined as the anterior palatine canal, or
its inferior opening. According to the definitions here given, incisor foramen has
the same meaning in human as in comparative anatomy while anterior palatine canal
is restricted to an appearance which presents itself only in man and a few animals.
The lamina passing backwards from before each incisor foramen corresponds to the
mesial palatine process of the intermaxillary bone in other animals, e. gr.,the carnivora:
while the incisor foramina are those which are seen largely developed in those
animals, and are the remains of a primitive communication between the nose and
mouth. The foramina of Scarpa lie in the suture between the laminae referred to.
They transmit the naso-palatine nerves; the nerve of the right side occupying,
according to Scarpa, the posterior one, which is usually largest, and that of the left
side, the anterior : but they are very inconstant. (Scarpa, Annot. Anatom.,
lib. ii. cap. 5.)
Fig. 39. FRONT PART OP THE PALATE AND Fig. 39.
ALVEOLAR ARCH OF AN ADULT.
Showing the lower opening of the anterior palatine
or incisor foramen. 1, 2, are placed on the palate plates
of the two superior maxillary bones ; 4, anterior pa-
latine foramen, in which is seen a partial division into
four openings the two lateral, with lines pointing to
them from 1 and 2, are the incisor foramina (foramina
of Stenson) ; the anterior and posterior, indicated by
3 and 4, are the naso-palatine, or foramina of Scarpa.
The external surface is divided into an anterior and a posterior part by
the malar process, a prominence presenting a large triangular roughness for
articulation with the malar bone, which abuts by its upper border
against the edge of the orbital surface, and at its inferior angle projects
outwards and downwards above the first molar tooth. The anterior
portion is excavated in a smooth curved notch at its internal margin
for the opening of the anterior nares. It is marked by a prominence
corresponding to the position of the fang of the canine tooth ; and in-
ternal to this is a slight depression, the incisor or myrtiform fossa ; while
between it and the malar process is the much deeper canine fossa, in
which arise the levator anguli oris and compressor nasi muscles. Above the
canine fossa, immediately below the margin of the orbit, is the infra-orbital
foramen, which transmits the superior maxillary nerve. The posterior
portion looks partly into the zygomatic, partly into the pterygo-maxillary
fossa. It exhibits a convexity, the tuber osity, which projects, backwards,
and is perforated by a number of foramina transmitting the superior dental
nerves and arteries.
46 BONES OF THE HEAD.
The ascending or nasal process projects upwards from the anterior and
internal part of the bone. Its surfaces are continuous with the external
and internal surfaces of the bone ; its internal surface, towards its summit,
is rough for articulation with the lateral mass of the ethmoid ; its anterior
border is rough for articulation with the nasal bone, and its summit serrated
for articulation with the frontal. Posteriorly, it articulates by a linear edge
with the lachrymal bone ; and external to this it presents a well-marked groove
for the lachrymal sac, the lachrymal groove, which is continued downwards
on the inner surface of the bone, between this process and the orbital plate,
and is converted into a canal by the lachrymal and inferior turbinated
bones.
The orbital service passes forwards to the margin of the orbit, and back-
wards to the spheno-maxillary fissure, and is bounded externally by the surface
for the malar bone, and internally by the lachrymal groove and a rough edge
which articulates with the lachrymal, ethmoid, and palate bones. It is inter-
rupted by a groove which commences in its posterior border, and leads for-
wards into a complete canal, the infra- orbital, of which the infra-orbital
foramen is the anterior termination. At the inner and fore-part of the orbi-
tal surface is a minute depression, which gives origin to the inferior oblique
muscle of the eye.
The nasal surface presents an oblique rough line beneath the ascending
process, for articulation with the inferior turbinated bone, and behind that
process the lachrymal groove. Behind the lachrymal groove is the large
opening into the sinus ; below and behind the sinus the surface is rough for
articulation with the palate bone ; and traversing the lower part of this
roughness is a smoother groove, passing downwards and forwards from the
posterior margin, and completing with the palate bone the posterior palatine
canal.
The maxillary sinus, or antrum of Highmore y is a large cavity lying
above the molar teeth and below the orbital plate, lined in the fresh state
by mucous membrane, and communicating with the middle meatus of the
nose. Its orifice is considerably diminished by contiguous bones, viz., by
the uncinate process of the ethmoid, the inferior turbinated bone, and the
palate bone.
THE PALATE BONE.
The palatal or palate bone forms the back part of the palate, and the
lateral wall of the nose between the superior maxillary bone and the
internal pterygoid process. In form it has a general resemblance to the
letter L, consisting of a horizontal and a vertical plate and three processes,
viz., the pyramidal process, extending outwards and backwards from the
junction of the horizontal and vertical plates, and the orbital and sphenoidal
processes, surmounting the vertical plate.
The palate bone articulates with its fellow, and with the superior maxillary,
ethmoid, sphenoid, vomer, and inferior turbinated bone.
The horizontal or palate plate presents posteriorly a thin free bor-
der, forming the limit of the hard palate, and giving attachment to the
soft palate or velum ; anteriorly it articulates with the palate plate of the
superior maxillary bone, and internally by a thick serrated border with its
fellow of the opposite side, forming with it a ridge for articulation with the
vomer, continuous with that of the superior maxillaries ; externally, at its
junction with the vertical plate, it is grooved by the extremity of the
posterior palatine canal. Its superior surface is smooth, and forms the back
THE PALATE BONE.
47
part of the floor of the nasal cavity ; its inferior surface is rough, and is
marked near its posterior border by a transverse ridge passing inwards from
the base of the pyramidal process, giving attachment to the tendinous fibres
of the tensor palati muscle.
Fig. 40.
Fi gt 40. THE PALATE BONE OF THE RIGHT SIDE, f
A, from the outside and behind ; B, from the inside.
1, the upper surface of the palatine plate; 2, its
posterior curved border or palatine arch ; 3, posterior
nasal or palatine spine ; 4, the rough surface of adjacent
articulation rising superiorly into the vomeric crest, as in
A ; 5 5, the nasal process ; 6, the ridge or shelf support-
ing the inferior turbinated bone ; 7, the sphenoidal
process ; 8, in B, the orbital process, showing a cellular
cavity ; 8', in A, its orbital surface ; 9, the spheno-
palatine notch ; 10, 11, 12, the pyramidal process 10,
rough surface of union with the external pterygoid plate,
11, with the internal ditto, and 12, the inter-pterygoid
smooth surface; 13 13, pala to-maxillary or posterior
palatine canal.
The vertical plate is very thin. Its internal
surface looks towards the nasal cavity, and is
divided into two parts, corresponding to the
middle and inferior meatus of the nose by a
nearly horizontal ridge which articulates with
the inferior turbinated bone. The external
surface is traversed by a smooth impression,
directed downwards and slightly forwards, the
upper part of which forms the internal wall
of the spheno-maxillary fossa, while the lower
part is hollowed into a deep groove, completing with the superior maxil-
lary the posterior palatine canal, which transmits the large descending
palatine nerve and accompanying vessels. In front of this canal the
external surface is in contact with the internal surface of the maxillary
bone and the side of the antrum ;, behind the canal it articulates inferiorly
with the hinder border of the maxillary, superiorly with the inner surface of
the pterygoid process.
The pyramidal process or tuberosity fits into the cleft between the ptery-
goid plates. It presents posteriorly a triangular surface which is smooth
and grooved, and completes the pterygoid fossa ; on its sides it is rough for
articulation with the borders of the pterygoid plates. Inferiorly, close to
its connection with the horizontal plate, are two small foramina, the posterior
and external small palatine foramina, the extremities of two minute canals
which transmit the smaller palatine nerves ; the external one is the smaller
and is inconstant.
The orbital process surmounts the anterior margin of the vertical plate.
It has the general appearance of an inverted pyramid, and has five surfaces,
two of which, the superior and external, are free, and the rest articulated.
The superior surface forms the posterior angle of the floor of the orbit ; the
external looks into the spheno-maxillary fossa, the anterior articulates with
the maxillary, the internal with the ethmoid, and the posterior, which is
small and only exists towards the extremity of the process, articulates with
the sphenoidal spongy bone.
The orbital surface is frequently found enlarged, extending upwards between the
48
BONES OF THE HEAD.
ethmoid and sphenoid as far as the frontal bone. This condition^ results from the
union with the palate bone of a separate centre of ossification, more usually united
with the ethmoid or sphenoid, and already described with the sphenoidal spongy
bone (p. 40).
The sphenoidal process curves upwards, inwards, and backwards from the
posterior part of the vertical plate. Its superior or external surface is in con-
tact with the sphenoidal spongy bone and the base of the internal pterygoid
plate, and is grooved for the completion of the ptery go-palatine canal ; its
internal or under surface looks to the posterior nares ; and at its base a third
surface looks forwards and outwards into the spheno-maxillary fossa. Its
inner extremity is in contact with the wing of the vomer.
The spheno-palatine foramen is formed in greatest part by the deep notch
between the orbital and sphenoidal processes, and is completed above by the
sphenoidal spongy bone. It leads from the spheno-maxillary fossa into the
nasal cavity, and transmits the internal nerves from Meckel's ganglion and
the nasal branch of the internal maxillary artery.
THE VOMER.
The vomer is a thin mesial bone, irregularly quadrilateral, and placed
vertically between the nasal fosss6. It articulates with the sphenoid, eth-
moid, palate, and maxillary bones, and with the septal cartilage of the nose.
As it usually becomes united by anchylosis, at an early age, to other
bones, and is frequently more or less absorbed and even distorted in some
of its parts, it can be best studied as a separate bone in young specimens.
Fig, 41.
Fig. 41. THE VOMER. |
A, from the right side ; B, from above.
1 ] ', the upper everted edges, or alse, on each
side of the hollow -which receives the rostrum
of the sphenoid; 2, the anterior or ethmoid
border, grooved to receive the septal cartilage
of the nose, and prolonged at x into a process
which rests upon the nasal crest ; 3, the pos-
terior or free border ; 4, the inferior or
maxillary and palatine border,
The part of the vomer which lies below the diagonal line
extending from its posterior to its anterior extremity is a
thin mesial plate, that which lies above this line consists of
two alee,, rising on each side of a mesial groove, in which lies
the septal cartilage of the nose. The alee posteriorly are
thick and expanded, and form the bifid posterior extremity of
the bone, which rests beneath the sphenoid. The superior
border of each ala, extending forwards from that point, arti-
culates edge to edge with the lamella projecting at the base
of the internal pterygoid plate, the sphenoidal process of the
palate bone, and the extremity of the rostrum of the sphe-
noid ; the anterior border, sloping downwards and forwards,
in contact with the septal cartilage, is free in the inferior part,
and is united superiorly by anchylosis on one or both sides with the
central plate of the ethmoid. The anterior extremity of the vomer forms
a short vertical line which fits in behind the nasal crest of the maxillaries,
and from the upper end of which a process projects forwards in the groove
MALAR AND NASAL BONES.
49
of the crest, while from its lower end a point projects downwards between
the incisor foramina. The inferior border articulates with the ridge or
crest which rises from the palate plates of the maxillary and palate
bones. The posterior border, thin, smooth, and unattached, separates the
posterior nares.
THE MALAR BONE.
The malar bone forms the most prominent part of the cheek, and, by a
deep plate, divides the orbit from the temporal fossa. It articulates by a
broad serrated surface near its anterior inferior angle with the malar process
of the superior maxillary bone, by a slenderer posterior process with the
zygoma, by a superior process with the frontal, and, continuously with that,
by the margin of its deep plate with the great wing of the sphenoid bone.
Between its sphenoidal and maxillary articulations a small portion of free
margin generally intervenes, which closes the anterior extremity of the
spheno-m axillary fissure. The facial surface is convex, and pierced by one
or more malar foramina, which pass through from the orbital surface and
transmit a small nerve and vessels. The orbital surface is concave from
above downwards, and enters into the formation
of the outer wall and floor of the orbit. The pj g> 49.
posterior surface is concave from side to side, and
looks into the temporal and zygomatic fossae ; it
is also pierced by a small foramen.
12
Fig. 42. RIGHT MALAR BONK.
A, from the outside ; B, from the inside.
1, superior or frontal angle and serrated edge ; 2,
posterior or external angle and serrated surface for the
zygoma ; 3, anterior or internal angle ; 4, inferior
angle ; from 1 to 2, the temporal border ; from 1 to 3,
the orbital border ; from 1 to 8, edge of articulation
with the frontal and sphenoid bones ; at 8, the notch
terminating generally the spheno-maxillary fissure;
from 2 to 4, the masseteric rough border; between
8, 3, and 4f the triangular serrated surface for articula-
tion with the superior maxillary bone ; 5, the external
surface ; 6, the deep or posterior surface ; 5 and 6, are
placed near the foramina for the temporo-malar nerves ;
7, the orbital surface, with the orbito-malar foramen.
THE NASAL BOXE.
The nasal bones form the bridge of the nose. They are thick and narrow
Fig. 43.
Fig. 43. RIGHT NASAL BONE, f
A, from the front ; B, from behind.
1, upper or frontal serrated border; 2, internal border
for adjacent articulation ; 3, external or superior maxillary
border ; 4, lower free border ; in B, 4 is placed at the
lower end of the groove for the nasal nerve.
above, but gradually become wider and thinner
below. The superior border of each is serrated,
and articulates with the frontal bone ; the inferior
unites with the lateral nasal cartilage ; the
external edge articulates with the ascending
process of the superior maxillary bone ; and the internal with its fellow,
of)
BOXES OF THE HEAD.
with the nasal spine of the frontal bone, and frequently with the perpen-
dicular plate of the ethmoid. The anterior surface, concave at its upper
part, convex in the rest of its extent, presents a minute vascular foramen ;
the posterior or nasal surface is marked by a groove for the passage of the
nasal nerve.
THE LACHRYMAL BONE.
The lachrymal bone, or os unguis, is a thin scale of bone placed at the
anterior and inner part of the orbit. It articulates superiorly with the
frontal bone, posteriorly with the orbital plate of the ethmoid ; anteriorly
it presents a longitudinal or vertical groove, and articulates with the
ascending process of the superior maxillary bone, completing with it the
groove for the lachrymal sac ; inferiorly it articulates in its greatest extent
with the orbital plate of the superior maxillary bone, while its anterior
Fig. 44. Fig. 44. RIGHT LACHRYMAL BONE, FROM THE OUTSIDE. |
1, upper or frontal border ; 2, the orbital surface ; 3, lachrymal
groove ; 4, the hooked process which meets the inferior turbinated bone.
grooved part projects downwards, taking part in the formation
of the lachrymal canal, and terminates in a pointed extremity,
hamulus lachrymalis, which fits into an angle between the
superior maxillary and inferior turbinated bone. The inner
surface looks superiorly to the anterior ethmoidal cells, and inferiorly to the
middle meatus of the nose.
THE INFERIOR TURBINATED BONE.
The inferior turbinated, or spongy bone, is a slender lamina, attached by
one margin from before backwards along the lateral wall of the nose, and
Fig. 45.
B
Fig. 45. THE INFERIOR TURBINATED BONE OF
THE RIGHT SIDE. f
A, from the outside ; B, from the inside.
1, anterior angle ; 2, posterior angle ; 1, 3, 2,
inferior free border ; 4, internal convex surface ;
5, part of the bone articulating with the uncinate
process of the ethmoid ; 6, portion articulating
with the lachrymal ; 7, the outer concave sur-
face ; 8, the maxillary process or deflected scale
of bone from the upper border, which, by union
with the superior maxillary, forms a part of the
inner wall of the maxillary sinus.
projecting into the nasal cavity, so as to
divide the middle from the inferior meatus.
It is slightly convoluted, its convexity look-
ing upwards and inwards, and its free mar-
gin being dependent, slightly thickened,
and rolled upon itself. The attached margin articulates anteriorly with the
oblique ridge below the ascending process of the superior maxillary bone,
and ascends abruptly to form the lachrymal process and complete the
lachrymal canal and articulate with the lachrymal bone ; behind this it bends
downwards in the maxillary process, forming part of the inner wall of the
antrum below the entrance into that cavity ; above and behind this, it
presents a small projection which articulates with the uncinate process of
the ethmoid, and posteriorly it is attached to the horizontal line on the ver-
tical plate of the palate bone.
INFERIOR MAXILLARY BONE.
51
This bone is marked by horizontal grooves and canals for vessels and
nerves, but not, as the turbinations of the ethmoid are, with vertical grooves
for the olfactory nerve.
THE INFERIOR MAXILLARY BONE.
The inferior maxilla, or lower jaw, is the thickest and strongest bone
of the face, and moves on the rest of the skull by means of a pair of
articular surfaces or condyles. It has the shape of an inverted arch bent
forwards upon itself, and consists of a middle larger and horizontal part
the body, and of two rami or ascending branches.
Fig. 46. THE INFERIOR MAX- Fig> 46>
ILLAKY BONE, FROM THE
RIGHT SIDE AND ABOVE. ^
1, the body; 2, the sym-
physis ; 3, the ramus ; 4, the
angle, near it the oblique ridges
marked by the attachment of
the masseter muscle ; 5, the
coronoid process ; 6, the con-
dyle or articular head ; 7, placed
in the sigmoid notch, points to
the front of the neck; 8, the
mental foramen ; 9, the external
oblique ridge ; 10, the inferior
dental foramen and mylohyoid
groove of the left side. This
figure represents a full set of
the teeth of the lower jaw in
middle life. (See also, for the
view of the inner surface of the lower jaw, figure 53, the vertical section of the skull.)
The body is marked in the middle by a vertical ridge, indicating the original
division of the bone into two lateral parts, and thence named the sym-
physis. The superior or alveolar border is hollowed out into sockets for
the teeth. The inferior border, thicker anteriorly than beneath the ramus,
is slightly everted in front, constituting the chin, or mentum, a prominence
peculiar to the human skull. On the outer surface, on each side of the
symphysis, below the incisor teeth, is a shallow depression, the incisor
/ossa, which gives origin to the levator menti muscle, and, more externally,
the labial or mental foramen, which transmits the facial branches of the
inferior dental nerve and artery. From beneath the mental foramen an
elevation, the external oblique line, extends upwards and outwards to
the anterior border of the ramus. The deep surface is marked, on each side
of the symphysis, along the inferior margin, by a depression, indicating
the anterior attachment of the digastric muscles, and above them by two
pairs of prominent tubercles, spince mentales, placed closely together, giving
attachment, the upper pair to the genio-hyo-glossi, and the lower to the
genio-hyoidei muscles. An oblique prominent line, the mylo-hyoidean ridge,
leading from beneath the spinee mentales, upwards and outwards to the
ramus, gives attachment to the mylo-byoideus muscle. Above this line
is a smooth depression for the sublingual gland, and beneath and external
to it another for the submaxillary gland.
The ramus is thinner than the body of the bone, and its border forms,
posteriorly and inferiorly with that of the body, an angle, called the angle
of the jaw. The external surface is flat and marked by slight unevenness,
and towards the angle by rirlges at the place of attachment of the masseter
B 2
52 BONES OF THE HEAD.
muscle. The internal surface presents at its middle the inferior dental
foramen, leading into the dental canal, which lodges the dental nerve
and vessels. Passing down from the sharp inferior margin of this foramen
is the mylo-hyoid groove (occasionally a canal for a short space), marking
the passage of the mylo-hyoid nerve with an accompanying artery and
vein. Behind this, inside the angle, 13 a marked roughness for the internal
pterygoid muscle.
Each ramus is surmounted by two processes, the condyle and the coro-
noid, which are separated by a deep excavation, the sigmoid notch. The
condyle is continued upwards from the posterior part of the ramus. It is
supported by a constricted portion, the neck, which presents anteriorly a
depression, into which the external pterygoid muscle is inserted. The con-
dyle is a transversely elongated convex articular process, whose major axis
is directed obliquely, so that if prolonged it would meet with that of its
fellow near the anterior margin of the foramen magnum. The coronoid
process is continued vertically upwards in front, from the anterior margin of
the ramus. It is pointed, and gives attachment by its margin and inner
aspect to the temporal muscle. At its base, in front, is a groove, to which
the buccinator muscle is attached.
The anterior margin of the ramus is placed at nearly a right angle to the alveolar
border. The angle of the jaw, which is the meeting of the posterior border of
the ramus with the base, is in the adult usually about 120 ; in infancy it is as
great as 140 or more ; in strongly developed jaws it may be diminished to 110 or less ;
and in old and toothless jaws it is increased. These changes are connected with a
variety of circumstances, among which may be noticed, the development of the
temporary and permanent teeth, the absorption of the alveolar arch in advanced age,
the elongation of the face and upper jaw towards adult life, and the varying state of
development of the masseter muscles at different periods.
THE HYOID BONE.
The hyoid bone, or os linguae,, is situated at the base of the tongue, and
may be felt between the chin and the thyroid cartilage. It is suspended
from the tips of the styloid processes of the temporal bones by a pair of
slender bands, the stylo-hyoid ligaments, which are osseous in most animals.
Hence, though not strictly a bone of the cranium or face, it properly falls
to be considered in this place. It is shaped like the letter u, and consists
of a body and two pairs of cornua.
Fig. 47. Fig. 47. THE HYOID BONE, FROM BEFORE, f
1, the prominent part of the body ; 2, the great cornu ;
3, the lesser cornu.
The lody, or central piece, is compressed from
before backwards, and lies in a plane, directed
downwards and forwards. Its anterior surface is
convex, and marked in the middle by a vertical ridge, on each side of which
are depressions for the attachment of muscles. Its posterior surface is
concave, and is directed towards the epiglottis.
The great cornua project backwards from the sides of the body, and end
in rounded extremities.
The small cornua, or cornicula, short and conical, project upwards and
backwards from the place of junction of the body with the great cornua,
THE SKULL AS A WHOLE.
53
and give attachment at their extremities to the stylo-hyoid ligaments. They
continue for a long time movable, as the cartilage which connects them
remains unossified till an advanced period of life.
THE SKULL AS A WHOLE.
Fig. 48. FRONT VIEW OP
THE SKULL OP A YOUNG
MAN OF ABOUT TWENTY
YEARS OP AGE. |
Placed with the anterior
nasal spine and the middle
of the meatus auditorius
externus in the horizontal
plane. (In this, as in most
other figures, the figures and
letters of indication are
placed only on one side.) 1 t
frontal eminence ; 2, middle
of the lower part of the frontal
bone, or glabella, between the
superciliary eminences, and
above the transverse suture
of union with the nasal and
superior maxillary bones ;
3, supra-orbital ridge at its
middle to the inside of the
figure is the supra - orbital
notch ; 4, the orbit the
figure is placed on the orbital
plate of the sphenoid bone,
between the foramen lacerum.
orbitale and the spheno-
maxillary fissure ; 5, the
anterior opening of the
nares, within which are seen
in shadow the nasal crest of
the superior maxillary bones,
the vertical plate of the eth-
moid bone, and on each side
the turbinated bones ; 6,
superior maxillary bone at
the canine fossa above the
figure is the infra - orbital
foramen ; 7, myrtiform, or incisor foramen ; 8, malar bone ; 9, symphysis menti and
median ridge; 10, body of the lower jaw, above the outer oblique ridge and the mental
foramen; 11, vertex, immediately over the coronal suture; 12, temporal fossa, at the
meeting of the frontal, parietal, temporal, and sphenoid bones; 13, zygoma; 14, mastoid
process ; 15, angle of the jaw ; 16, mental angle. In this skull there are fourteen teeth
in each jaw, the wisdom teeth having not yet appeared.
J5
THE SUTURES.
The sutures of the skull are best distinguished when named from the
bones between which they lie, as, for example, occipito-parietal, occipito-
mastoid, fronto- ethmoid, parieto-sphenoid, &c. Those which occur in the
arch of the skull require more particular notice. The cranium is intersected
superiorly by three great serrated sutures, two of which, placed transversely,
correspond to the anterior and posterior margins of the parietal bones, while
the third lies in the middle line and passes between them. On each side
also there runs an irregular longitudinal line of suture from the malar to the
54
BONES OF THE HEAD.
occipital bone, bounded by the frontal and parietal bones above, and the
malar, sphenoid, and temporal bones below.
Fig. 49.
Fig. 49. LATERAL OR PROFILE VIEW OF THE SAME SKULL AS THAT REPRESENTED IN
THE PRECEDING FlGURE. ^
Placed so that a horizontal line passes through the anterior nasal spine and meatus
auditorius externus. 1, frontal bone ; 2, parietal bone figures 1 and 2 are placed above
the temporal ridge of these bones ; x x , coronal suture ; 3, occipital bone the figure
is placed at the lower end of the lambdoidal suture, and at its meeting with the addi-
tamentum suturse squamosse and additamentum suturge lambdoidalis ; 3', external or
posterior occipital protuberance ; 4, great wing of the sphenoid bone, between the frontal,
anterior inferior angle of the parietal and squamous part of the temporal bones ; 5, the
summit of the squamous part of the temporal bone ; 6, at the lower part of the same and
at the root of the zygoma immediately over the meatus auditorius externus; 7, mastoid
portion of the temporal bone, in front of which is the mastoid process the figure is close
to the mastoid foramen ; 8, the left condyloid process of the occipital bone ; 9, the
anterior opening of the nares or nasal notch; 10, the inner wall of the orbit, on the
lachrymal bone; 11, the malar bone, close to its junction with the zygoma ; 12, superior
maxillary bone the figure is placed on the body behind the canine fossa ; 13, ramus of
the lower jaw, at its middle; 14, body of the lower jaw, near the mental foramen.
The fronto-parietal, or coronal suture, connects the frontal and the two
parietal bones. It commences at each side, about an inch behind the
external orbital process of the frontal bone, above the great wing of the
sphenoid, and mounts upwards and backwards to the vertex. It presents
the most marked dentations in the middle of each lateral half ; at the
summit the serrated surface is oblique, the frontal bone overlapping the
parietal, while similarly at the lower part the parietal overlaps the frontal.
The occipito-parietal, or lambdoidal suture, situated between the occipital
SUTURES. 55
and parietal bones, inclines downwards and outwards on each side and has
somewhat of the form of the Greek letter A. The occipito-mastoid suture
(additamentum suturce, lambdoidalis) is in continuation with it.
The parietal, or sagittal suture, connects the two parietal bones : it is
continued in children, and not unfrequently in adults, by a suture between
the two halves of the frontal bone, the frontal suture.
The spheno-parietal suture, the line of contact of the parietal bone and
great wing of the sphenoid, is about half an inch in extent. It is absent
only in very rare cases, and then the frontal and temporal bones come into
contact.
The temporo-parietal suture consists of two very distinct parts, the
squamous suture, arched in direction, in which the scale-like margin of the
squamous portion of the temporal bone overlays the similar margin of the
parietal, and the parieto-mastoid suture (additamentum suturce squamosce),
which is thick and serrated.
From the nature of the squamous suture, the inferior margins of the parietal bones
cannot be pressed outwards by forces acting either from above or from within, without
at the same time pushing before them the squamous margins of the temporals.
When the pars squamosa is thus acted on, it may either bulge outwards alone, or may
press downwards the base of the pars petrosa. Both phenomena are observable in
broad skulls.
OSSA TRIQTTETRA. Supernumerary ossicles are found in a great number of skulls,
interposed between the cranial bones, like islets in the sutures. They are called ossa
triquetra, ossa Wormii, ossa suturamcm, &c. They are of irregular form, with margins
adapted to the character of the sutures in which they are situated. They are most
frequently found in the occipito-parietal suture, where they occur sometimes in great
numbers, more or less symmetrically arranged; in other instances, one or several bones
of considerable size may occupy the place of the superior part of the occipital. They
are less frequent in the parietal suture and at the anterior fontanelle, are found only
in small numbers in the fronto-parietal suturCj and rarely occur in the squamous.
A single triquetrous bone intervenes sometimes between the parietal and sphenoid ;
and still more frequently between the parietal and the place of meeting of the squamous
and mastoid portions of the temporal.
GENERAL CONFORMATION OP THE SKULL.
THE EXTERIOR.
The surface of the skull may be conveniently divided into superior,
inferior, anterior, and lateral regions./
The SUPERIOR REGION, extending from the supra-orbital ridges iu ^ront to
the superior curved line of the occipital bone behind, and bounded laterally
by the temporal ridges, is smooth and convex, covered only by the muscular
fibres and fascia of the occipito-frontalis muscle and the integument. It is
of an oval form, broader in the parietal than the frontal region, flattened in
front, and projecting somewhat in the middle behind.
The ANTERIOR REGION of the skull, below the forehead, presents the
openings into the orbits, bounded by the frontal, malar, and superior
maxillary bones ; and between the orbits, the bridge of the nose, formed by
the nasal bones and ascending processes of the superior maxillaries. Below
the nasal bones is the nasal aperture, of an inverted heart shape : its thin
margin gives attachment to the nasal cartilages, and projects forwards in the
middle line below as the nasal spine. Below the nasal aperture are the
incisor fossae of the upper jaw ; below the orbits are the canine fossae ; and
external to the canine fossae are the prominences of the cheeks, formed by
the anterior inferior parts of the malar bones. The lower jaw completes the
56 BONES OF THE HEAD.
skeleton of the face below. The foramina in this region, on each side, are
the supra-orbital foramen or notch in the superior margin of the orbit, the
infra-orbital foramen below the inferior margin of the orbit, the mental
foramen of the lower jaw, and the small irregular foramina of the malar
bone.
The orbits are pyramidal fossae, irregularly quadrilateral, with their bases
Fig. 50.
Fig. 50. SECTION OP THE SKULL OP A MAN OP MIDDLE AGE, IN TWO PLANES, ONE OP
WHICH PASSES VERTICALLY THROUGH THE LEFT ORBIT TO THE INNER SIDE OP ITS
MIDDLE, AND THE OTHER OBLIQUELY FROM BEHIND THE ORBIT, BACKWARDS AND
OUTWARDS, THROUGH THE TYMPANUM AND MASTOID PROCESS, AND TO THE OUTSIDE
OP THE FORAMEN ROTUNDUM AND FORAMEN OVALE.
1, section of the frontal Lone in the roof of the orbit ; 2, left nasal bone ; 3, nasal
process of the superior maxillary bone ; 4, left lachrymal bone, and in front the groove
of the nasal duct ; 5, placed on the os planum of the ethmoid bone, below the anterior of
the ethmoid foramina ; 6, is placed below the root of the lesser wing of the sphenoid
bone, between the optic foramen and the posterior internal orbital or ethmoid foramen,
and close to the foramen lacerum orbitale ; 7, floor of the orbit, formed by orbital plate of
the superior maxillary bone the figure is placed close to the inside of the infra-orbital
groove ; 8, is placed on the orbital plate of the palate bone, in front of and above the
spheno-pfc^tlne foramen and spheno-maxillary fossa ; 9, marks the upper extremity of
the posterior palatine (or palato-maxillary) canal ; towards 11 in the fossa is the opening
backwards of the Vidian canal; 10, the cranial opening of the foramen rotundum its
anterior opening is seen in the spheno-maxillary fossa ; 11, section of the great wing of
the sphenoid bone outside the round and oval foramina ; 12, is placed close to and
between the spinous and oval foramina; 13, is placed on the anterior surface of the
petrous bone, near the apex, or in the fossa of the Gasserian ganglion ; towards the orbit
are seen the foramen lacerum anterius, sigmoid groove of the internal carotid artery, and
pituitary fossa, below the figure and externally the hiatus Fallopii ; 14, the pituitary
fossa, with the anterior and posterior clinoid processes ; 15, section of the petrous bone
above the labyrinth ; two of the semicircular canals are opened ; immediately below is
the tympanum. The inner wall is seen with the promontory, fenestra ovalis and pyramid
in shadow ; forwards, at x , the opening of the tympanum towards the Eustachian canal,
and backwards, below 16, the opening into the mastoid cells ; 17, left styloid process
that of the right side is seen in perspective below the skull, close by the occipital condyle;
18, tuberosity of the superior maxilla; 19, canine fossa; 20, nasal notch and anterior
nasal spine ; 21, inner wall of the antrum seen by the removal of its outer wall ; above
the figure is the maxillary process of the inferior turbinated bone, and over that an
irregular fissure, viz., the opening of the antrum into the middle meatus of the nose, and
above that the uncinate process of the ethmoid bone.
EXTERIOR OF THE SKULL. 57
directed forwards and outwards, their inner walls being nearly parallel, and
their outer walls diverging so much as to be at right angles one to the other.
The roof of each orbit is formed by the orbital process of the frontal and the
small wing of the sphenoid bone ; the floor consists of the orbital processes
of the malar and superior maxillary bones, and of the small orbital surface
of the palate bone at the back part ; the inner wall consists of the ascending
process of the superior maxillary, the lachrymal, the ethmoid, and the
sphenoid bone ; and the outer wall of the orbital surfaces of the malar bone
and great wing of the sphenoid. The sphenoidal fissure (foramen lacerum
orbitale), at its inner extremity, occupies the apex of the orbit, while its
outer and narrower part lies between the roof and the external wall. The
foramen opticum is internal and superior to the sphenoidal fissure. In the
angle between the external wall and the floor is the spheno-maxillary fissure,
bounded by the sphenoid, palate, superior maxillary, and malar bones, and
leading into the spheno-maxillary fossa at its back part, and the zygomatic
fossa at its fore part. Passing forwards from the margin of the spheno-
maxillary fissure is the commencement of the infra-orbital canal, grooving
the posterior part of the floor of the orbit. At the fore part of the inner
wall is the lachrymal groove, formed by the superior maxillary and lachrymal
bones, and leading into the nasal duct : further back, between the ethmoid
and frontal bones are the anterior and posterior internal orbital foramina ;
in the anterior margin of the roof is the supra-orbital foramen or notch ;
and in the outer wall are the minute foramina which perforate the malar bone.
The LATERAL REGION" of the skull presents in a horizontal line from
behind forwards the mastoid process, the external auditory meatus, the
glenoid fossa, with the condyle of the lower jaw, and the zygomatic or
malar arch, formed by the zygomatic process of the temporal bone and the
posterior part of the malar. When the head of the lower jaw is in the
glenoid cavity, the coronoid process lies internal to the malar arch. The
upper part of the space bridged over by this arch is called the temporal
fossa, the lower part the zygomatic fossa, the line of division being the rough
ridge which divides the external surface of the great wing of the sphenoid
bone into an upper and lower portion. The temporal fossa is occupied by
the temporal muscle ; it is bounded superiorly by the temporal ridge ; and
the frontal, parietal, sphenoid and malar bones take part in its formation.
The zygomatic fossa is occupied in part by the external pterygoid muscle ;
its wall is formed internally by the external pterygoid plate, superiorly by
the lower part of the great wing of the sphenoid bone, and anteriorly by the
superior maxillary. Inferiorly the external pterygoid plate comes nearly
into contact with the superior maxillary bone, but is usually separated from
it, though not always, by a thin portion of the pyramidal process of the
palate bone; superiorly, it is divided from it by the ptery go-maxillary
fissure, a vertical opening, which leads into the spheno-maxillary fossa, and
which is continued above into the outer extremity of the horizontal spheno-
maxillary fissure opening into the orbit.
The spheno-maxillary fossa is the space which lies in the angle between
the pterygo-maxillary fissure and the inner or posterior half of the spheno-
maxillary fissure. It is bounded posteriorly by the external pterygoid
process and inferior division of the anterior surface of the great wing of
the sphenoid bone, anteriorly by the tuberosity of the superior maxillary
bone, and internally by the vertical plate of the palate bone. Into this
narrow space five foramina open, viz., on the posterior wall, the foramen
rotund urn, the Vidian canal, and, between the sphenoidal process of the
58
BONES OF THE HEAD.
palate bone and the root of the internal pterygoid plate, the ptery go-
palatine canal; on the inner wall, the spheno-palatine foramen formed by
the palate bone and a small part of the sphenoidal spongy bone, and
opening into the nasal cavity ; and inferiorly, the posterior palatine canal,
which leads down to the palate between the palatal and superior maxillary
bones.
Fig. 51. Fig. 51. BASIS OF THE
SKULL, VIEWED FROM
BELOW, WITHOUT THE
INFERIOR MAXILLARY
BONE, OF A MAN OF
ABOUT TWENTY YEARS
OF AGE. 4
1, palatine plate of the
superior maxillary bone
the figure is placed near
the mesial suture ; 2, pala-
tine plate of the palate
bone the figure is placed
below the transverse su-
ture between the palate
and superior maxillary
bones ; 3, the anterior pa-
latine foramen, showing
four smaller foramina
within ; 4, is placed out-
side the posterior palatine
foramen, inside the tube-
rosity of the superior max-
illa, and in front of the
smaller posterior palatine
foramina in the pyramidal
process of the palate bone;
5, inner surface of the ex-
ternal pterygoid plate of
the sphenoid bone ; 6, is
placed within the posterior
opening of the nares on the
inner surface of the inter-
nal pterygoid plate ; 7, is
upon the upper part of
the posterior edge of the
vomer ; x marks the pos-
terior opening of the pte-
rygo-palatine canal, and is
placed above or in front of the posterior opening of the Vidian canal in the foramen
lacerum anterius ; 8, spheno-maxillary fissure leading into the orbit ; 9, foramen
spinosum ; 10, foramen ovale ; 11, is placed on the apex of the petrous bone, between
the foramen lacerum anterius and the inferior opening of the carotid canal; 12, is placed
in the jugular (or digital) fossa of the temporal bone, and indicates the foramen lacerum
posterius ; 13, on the articular eminence of the inner root of the zygoma in front of the
glenoid cavity of the temporal bone ; 14, meatus auditorius externus; 15, glenoid cavity
in front of the fissure of Glaser ; 16, tympanic plate or posterior part of the glenoid
cavity, close to the styloid process, below which is seen the stylo-mastoid foramen ; 17,
mastoid process, and to its inside the digastric and occipital grooves ; 18, basilar process
of the occipital bone, and in front the mark of the still incomplete union with the body of
the sphenoid bone ; 19, condyloid articular process of the occipital bone ; 20, is placed in
the foramen magnum, and points to the lower opening of the anterior condyloid foramen ;
21, posterior opening of the posterior condyloid foramen ; 22, jugular process of the
occipital bone, to its inner side the jugular notch, to its outer and above, the stylo-
mastoid foramen ; 23, is placed on one side, in front (above in the figure) of the external
occipital protuberance, and the line indicates the upper part of the external occipital
spine ; 24, superior curved line of the occipital bone ; 2.5, inferior curved line ; 26,
groove and ridge of insertion of obliquus capitis superior muscle.
EXTERIOR OF THE SKULL. 59
The INFERIOR REGION, or external base of the skull, extending from the
incisor teeth to the occipital protuberance, and transversely from the
mastoid process and dental arch on one side to the corresponding points on
the other, is divisible, on removal of the lower jaw, into an anterior,
middle, and posterior part.
The anterior part consists of the palate and the alveolar arch. It is
traversed longitudinally by a mesial suture, and transversely by that
between the maxillary and palate bones. Anteriorly, in the middle line, is
the anterior palatine foramen, with the four smaller foramina contained
within it; posteriorly, on each side, at the base of the alveolar border, is
the posterior palatine foramen, and externally and posteriorly to that, the
posterior and external small palatine foramina. The palate is surrounded
in front and on the sides by the alveolar arch and teeth of the upper jaw.
The middle part, extending back to the front of the foramen magnum, is
the most complicated. Its central portion has been called the guttural fossa.
In the middle line is the basilar process of the occipital bone, and in front of
that the body of the sphenoid bone, concealed anteriorly by the extremity of
the vomer. On each side, the petrous portion of the temporal bone reaches
as far forwards as the extremity of the basilar process; and between the
petrous and squamous portions of the temporal is the back part of the great
wing of the sphenoid bone. Between this division of the base of the skull
and the palate are the posterior nares, separated by the vomer, and bounded
above by the body of the sphenoid bone, below by the horizontal plates of
the palate bones, and on the sides by the internal pterygoid processes.
Between the pterygoid plates is the pterygoid fossa; and placed in an
oblique line backwards and outwards from this are the foramen ovale,
foramen spinosum, and processus spinosus; while behind and parallel to
these is a groove for the Eustachian tube, formed by the margins of the
sphenoid bone and pars petrosa, leading into the Eustachian orifice, and in
a line with the fissure of Glaser. Between the apex of the pars petrosa, the
basilar process, and the sphenoid bone, is the foramen lacerum anterius basis
cranii, called also foramen lacerum medium, on the external wall of which
opens the carotid canal, and on the anterior the Vidian canal ; it is closed
inferiorly by a plate of cartilage, but its area is crossed by the internal
carotid artery and by the Vidian nerve. Behind the pars petrosa, and
bounded posteriorly by the jugular fossa of the occipital bone, is the foramen
jugulare, or foramen lacerum posterius : it is divided into a large external
and posterior part, bounded anteriorly by the jugular fossa of the temporal
bone, and occupied by the jugular vein; and a small anterior and inner
part, bounded by a portion of the pars petrosa distinct from the jugular
fossa, and transmitting the glosso-pharyngeal, vagus, and spinal accessory
nerves. The two parts of the foramen lacerum posterius are sometimes
completely separated by a spiculum of bone. Anterior to this opening is
the carotid foramen, external to it is the stylo-mastoid foramen and styloid
process, and internal to it is the anterior condyloid foramen.
The posterior part of the inferior region presents on each side of the fore
part of the foramen magnum, in a transverse line outwards, the occipital
condyle, the rough surface for the rectus capitis lateralis muscle, the occi-
pital groove of the temporal bone, the digastric fossa, and the mastoid
process. Behind is the inferior division of the expanded part of the occipital
bone, with its ridges and muscular impressions.
60
BONES OF THE HEAD.
THE INTERIOR OF THE SKULL.
1. THE CRANIAL CAVITY. The walls of the cranium present two layers
of compact tissue, the outer and inner tables, and between these, in the
greater part of their extent, cancellated substance, called diploe. The inner
Fig. 52. INTERNAL
BASIS OP THE SKULL,
OPENED BY A HORI-
ZONTAL INCISION ONE
INCH ABOVE THE Su-
PRA-ORBITAL ARCHES
AND EXTERNAL OC-
CIPITAL PROTUBER-
ANCE. ^
1, anterior fossa and
roof of the orbit, as
formed by the frontal
bone, marked by im-
pressions of cerebral
convolutions ; 2, is close
to the foramen ccecum
and in front of the
crista galli and cribri-
form plate of ethmoid ;
3, is close behind the
ethmoidal spine of the
sphenoid and behind
the cribriform plate ;
4, lesser wing of Ingras-
sias, terminating pos-
teriorly in the anterior
clinoid process, inside
which the inner open-
ing of the optic fo-
ramen is seen ; 5, the
pituitary fossa, in front
of it the olivary emin-
ence and transverse
groove of the optic
commissure ; 6, the inclined plate of the body of the sphenoid, or dorsum Bellas, ter-
minating in the posterior clinoid processes, and to the side of these the sigmoid groove of
the internal carotid artery ; 7, foramen rotundum, to the inner side of which anteriorly,
but not seen, is Ihe foramen lacerum orbitale ; 8, foramen ovale ; 9, foramen spinosum ;
10, is placed on the ridge of the petrous bone, near its apex, and to the inside of the
hollow occupied by the Gasserian ganglion ; in front of this is the foramen lacerum ante-
rius ; 11, is placed in front of the eminence of the superior semicircular canal of the
labyrinth, and behind the hiatus Fallopii ; 12, is upon the prominent ridge of the petrous
bone, marked by the superior petrosal groove ; 13, is upon the posterior surface of the
petrous bone to the inside, the meatus auditorius internus, behind, the scale of bone
covering the aqueduct of the vestibule ; 14, basilar groove; 15, inner or upper opening
of the anterior condyloid foramen ; 16, jugular part of the foramen lacerum posterius;
17, outer part of the groove of the lateral sinus, where it crosses the lower angle of the
parietal bone ; 1 8, internal occipital protuberance, and between it and the foramen
magnum, the internal occipital spine; between 17 and 18, the upper part of the groove
of the lateral sinus, between 17 and 16 the lower part ; 19, cerebellar fossa.
or vitreous table, has a smooth, close-grained, shining appearance, is hard and
brittle, and is thrown into irregular digitate impressions corresponding to the
convolutions of the brain. The thinnest portions of the cranial wall are the
cribriform plate of the ethmoid and the orbital plates of the frontal bone,
in both of which the diploe is entirely absent ; in the middle part of the
inferior occipital fossae, and in the squama and glenoid fossa of the temporal,
the bone is also very thin and compact.
INTERIOR OF THE SKULL. 61
The upper part of the cranial cavity forms an unbroken arch ; the lower
part is divisible into three parts or fossae having different levels.
The anterior fossa, formed by the orbital plates of the frontal bone, the
small wing of the sphenoid, and the cribriform plate of the ethmoid, sup-
ports the anterior lobes of the brain. It is deepest opposite the ethmoid
bone, and convex over the orbits. It is pierced by the foramina of the
cribriform plate, and by the foramen coecum in front of the crista galli of
the ethmoid bone.
The middle fossa presents a mesial and two lateral parts. The mesial
part is small, being formed by the olivary process and sella turcica of the
sphenoid bone, and limited behind by the dorsum sellse. The lateral part
on each side, formed by the great wing of the sphenoid, the squamous part
of the temporal, and the anterior surface of the petrous part, lodges the
middle lobe of the brain. The foramina of the middle fossa are the fora-
men opticum, the sphenoidal fissure, foramen rotund um, foramen ovale,
foramen spinosum, foramen lacerum medium, and hiatus Fallopii.
The posterior fossa t deeper and larger than the others, extends back to the
occipital protuberance, and lodges the cerebellum and medulla oblongata.
The occipital bone and the petrous and mastoid portions of the temporal
bone take part in its formation. In the posterior surface of the pars pe-
trosa, which limits this fossa anteriorly on each side, is the internal audi-
tory meatus, below it is the foramen lacerum posterius, below and internal
to that is the anterior condyloid foramen, and in the middle line is the
foramen magnum.
Grooves for Bloodvessels. The groove of the middle meningeal artery
commences at the foramen spinosum of the sphenoid bone, and ramifies
principally on the squamous portion of the temporal bone and on the
parietal. The groove of the internal carotid artery lies on the side of the
body of the sphenoid bone, and terminates on the internal margin of the
anterior clinoid process. The groove of the superior longitudinal sinus,
commencing at the foramen coecum in front of the crista galli of the ethmoid
bone, enlarges as it passes backwards in the middle line of the roof of the
skull, and terminates at the internal occipital protuberance. At that point
commence the grooves of the lateral sinuses, which pass outwards on the
occipital bone, cross the posterior inferior angles of the parietal bones,
descend on the mastoid portions of the temporal bones, run inwards again on
the occipital, and turn forwards to terminate at the jugular foramen. The
groove of the inferior petrosal sinus lies between the petrous portion of the
temporal bone and the basilar process ; that of the superior petrosal sinus
extends along the superior angular edge of the petrous portion.
THE NASAL CAVITIES AND COMMUNICATING SINUSES. The nasal cavities
are placed one at each side of the middle line, being separated by a vertical
septum. They open in front and behind by the anterior and posterior
nares already described, and communicate by foramina with the sinuses of
the frontal, ethmoid, sphenoid, and superior maxillary bones. Their vertical
extent, as well as that from before backwards, is considerable, but the
transverse width of each is very limited, especially in the upper part.
The internal wall, or septum narium, is formed principally by the central
plate of the ethmoid bone and the vomer ; but the frontal spine, the rostrum
of the sphenoid bone, and the crests of the maxillary and palate bones
likewise enter into its composition. It presents a great angular deficiency
in front, which in the recent state is filled up by the septal cartilage. In
62
BONES OF THE HEAD.
very many cases it deviates from the middle line, and more frequently to the
left than to the right side. The concave side is that on which the ala of
the vomer is most intimately connected with the ethmoid.
Fig. 53.
23
Fig. 53. VERTICAL SECTION OF THE ADULT SKULL IN AN ANTERO-POSTERIOR
PLANE, PASSING A LITTLE TO THE LEFT OF THE MIDDLE, SHOWING THE SEPTUM
NARIUM, &c. 4
1, nasal bone; 2, perpendicular plate of the ethmoid bone, with olfactory foramina
and grooves at its upper part ; 3, vomer ; 4, nasal process of the right superior maxillary
bone, forming part of the wall of the right nasal fossa ; below this the anterior extremity
of the right inferior turbinated bone, and below that, at x , the fore part of the right
inferior meatus of the nose ; 5, crista galli ; 6, inner surface of the frontal bone ; 7, of
the parietal bone; 8, squamous part of the temporal, all these being marked by grooves
of cerebral convolutions and meningeal vessels ; 9, placed on the occipital bone below the
internal or anterior occipital protuberance ; 10, the posterior or external occipital pro-
tuberance; 11, placed on the condyloid process below the anterior condyloid foramen;
12, placed on the posterior surface of the petrous bone below the meatus auditorius
internus ; between 9 and 12 the groove of the right lateral sinus, crossing also the
raastoid bone ; 13, placed above the sella turcica and between the anterior and posterior
clinoid processes ; 14, part of the left frontal sinus, the figure being placed on the left
side of the septum, between the left and the right sinus ; 15, part of the left sphenoidal
sinus, the figure being placed on the septum of the sinuses ; 16, hard palate and alveolar
ai-ch the figure is placed near the lower opening of the posterior palatine canal, and the
grooves which extend forwards from it ; 17, anterior nasal spine; 18, section of the left
superior maxillary bone, and near the place to which the line points, the section of the
lower part of the anterior palatine canal ; 19, placed on the inner surface of the ramus of
the lower jaw, below the sigmoid notch, and above the inferior maxillary foramen ;
20, inner surface of the body of the jaw on the oblique or mylo-hyoid ridge ; 21, section
of the lower jaw, near the symphysis ; behind the symphysis, and between 21 and 22,
the mental or genioid spines ; 23, groove for the mylo-hyoid nerve.
NASAL CAVITIES AND SINUSES.
63
The roof is horizontal in its middle part, but sloped downwards before and
behind. The middle part is formed by the cribriform plate of the ethmoid
bone, the fore part by the frontal and nasal bones, and the back part by the
sphenoidal spongy bone.
The floor, formed of the palate plates of the maxillary and palate bones,
is smooth, and concave from side to side. Towards its anterior extremity is
the superior orifice of the incisor canal.
Fig. 54. VERTICAL ANTERO- Fij. 54.
POSTERIOR SECTION OP A
PART OF THE CRANIUM, TO
THE LEFT OF THE MIDDLE,
VIEWED FROM THE INNER
SIDE, TO SHOW THE OUTER
WALL OF THE LEFT NASAL
FOSSA, &o. i
1, nasal bone ; 2, nasal pro-
cess of the superior maxillary
bone ; 3, ascending plate of the
palate bone ; 4, superior turbi-
nated bone of the ethmoid
below it the superior meatus,
behind it the opening into the
left sphenoidal sinus ; 5, the
middle turbinated bone below
it the middle meatus, in which
are seen the uncinate process of
the ethmoid, and, between it
and the inferior turbinated
bone, the opening into the
maxillary sinus ; superiorly
and anteriorly, the opening of the infundibulum and anterior ethmoidal cells ; behind it,
and above 3, the spheno-palatine foramen ; 6, the inferior turbinated bone below it the
inferior meatus x x , below these marks the section of the palatine plates of the left
palate and superior maxillary bones ; 7, the left frontal sinus ; 8, the left sphenoidal
sinus ; 9, the left optic foramen in the root of the lesser wing of the sphenoid and
anterior clinoid process; 10, the ridge of the dorsum sellse divided ; and between 9 and
10, the sella turcica; 11, is placed on the posterior surface of the petrous bone, close to
the internal auditory meatus ; 12, is placed on the basilar process of the occipital bone,
close to the foramen lacerum posterius ; 13, is placed below the anterior condyloid
foramen ; 14, left styloid process ; 15, external, and 16, internal pterygoid processes ;
17, posterior palatine canal and grooves.
The external wall is the most extensive. The bones which take part in
its formation are the nasal, superior maxillary, ethmoid, inferior spongy,
and palate bones, aud the internal pterygoid plates. The superior and
inferior turbinated processes of the ethmoid bone (superior and middle
turbinated bones), and the inferior spongy bone, projecting inwards,
overhang three galleries or meatus. The superior meatus, very short, is
placed between the superior and inferior turbinated processes of the ethmoid
bone ; into it open anteriorly the posterior ethmoidal cells, and posteriorly
the spheno-palatine foramen and sphenoidal sinus. The middle meatus, the
space between the inferior turbinated process of the ethmoid and the inferior
spongy bone, communicates at its fore part with the anterior ethraoidal cells,
and, by means of the infundibulum, with the frontal sinus, while in its
middle is the opening of the maxillary sinus. The inferior meatus, longer
than the others, lies below the inferior spongy bone, between it and the floor
of the nasal cavity ; in its fore part is the orifice of the nasal duct.
64 BOKES OF THE HEAD.
The SINUSES are hollows within certain cranial bones, which communicate
with the nasal cavities by narrow orifices, and are named ethmoidal, frontal,
sphenoidal, and maxillary. The maxillary sinus begins to be formed about
the fourth month of foetal life ; the frontal, ethmoidal and sphenoidal first
appear during childhood, but remain of small size up to the time of puberty,
when they undergo a great enlargement. In advanced life they all increase
in size by absorption of the cancellated tissue in their vicinity. The
ethmoidal sinuses are numerous smaller spaces in the lateral masses of the
ethmoid bone. The frontal sinuses, formed in the substance of the frontal
bone, communicate with the middle meatus narium through the infundibula
of the ethmoid bone. The sphenoidal sinuses, hollowed out in the sphenoid
bone, and limited below and in front by the sphenoidal spongy bones, op n
anteriorly opposite the posterior ethmoidal cells.
The maxillary sinus is of an irregular pyramidal form ; its apex points to
the malar tuberosity ; its sides are formed by the orbital and lateral plates
of the superior maxillary bone ; its internal wall, which separates it from
the nasal cavity, is formed by the maxillary, palate, and inferior turbinated
bones, and the uncinate process of the ethmoid ; an irregular gap or deficiency
being left between the uncinate process and the inferior turbinated bone, by
which the sinus opens into the middle meatus. The alveolus of one of the
molar teeth generally forms a marked projection in the floor of the sinus, at
its outer part.
DEVELOPMENT OF THE SKULL.
EARLY DEVELOPMENT OP THE HEAD. When the head of the embryo has become
so far developed as to rise completely out from the plane of the germinal mem-
Fig. 55. Fig. 55. MAGNIFIED SIDE VIEW OF THE HEAD
AND UPPER PART OF THE BODY OP AN
EMBRYO-CHICK OP THE FOURTH DAY (adapted
from Remak and Huxley).
1, chorda dorsalis ; 2, three of the upper
2 /A> / N. vJ^^ primitive cervical vertebrae; C 1 , first cerebral
fi^X . ^\^ vesicle, with the nasal fossa below; C 2 , second
part of the first cerebral vesicle, or thalamus
opticus, with the eye below it ; C 3 , the middle
cerebral vesicle; C 4 , the cerebellum, between
which and the cervical vertebrae is the medulla
oblongata, these two constituting the first and
second parts of the third cerebral vesicle. At
the upper part of the chorda dorsalis, where it
afterwards reaches the post-sphenoid, is seen the
rectangular bend of the middle of the cranium,
which takes place at the sella turcica ; and in
front of this, towards the eye, the pointed infun-
dibulum ; V, the rudiment of the trigeminus nerve ; VII, the facial ; VIII, the vagus ;
IX, the hypoglossal ; in front and below these numbers respectively, first the upper and
lower jaw, or first branchial arch, with the first cleft, which becomes the meatus audi-
torius externus ; and lower down the second, third, and fourth branchial arches and
clefts in succession ; in front of these the aortic bulb attaches the heart ; between VII
and VIII, the auditory vesicle.
brane, two curvatures forwards are observed, the posterior of which is at the
junction of the head with the spinal column, while the anterior is opposite the second
cerebral vesicle, and is so placed that the fore part of the skull is bent at right angles
to the back part. Behind the anterior curvature, the ventral margins of the dorsal
plates are thrown on each side into four processes, the branchial or visceral arches,
behind each of which is a fissure or branchial cleft in which the epithelial layer of
DEVELOPMENT OF THE SKULL.
65
the gullet passes out and becomes continuous with that of the integument. In a
human embryo of three weeks of age all the arches are visible (Thomson). The first
or highest visceral arch is the first to appear, and it is likewise the first to unite with
its fellow of the opposite side : it forms by its lower part the outline of the lower jaw.
The posterior or upper part of the first branchial cleft remains as the external aperture
of the ear, the tympanic cavity and the Eustachian tube, while its anterior part together
with the whole of the other branchial clefts are filled up. Connected with the upper
edge of the first visceral arch, at its origin, a process is developed, the maxillary
lobe, which passes forwards beneath the eye, forming the side part of the face. The
eyes are formed in connection with the sides of the anterior cerebral vesicle, and, in
front of them, a quadrilateral mesial lobe, the middle frontal process, passes down and
forms the nose and middle part of the upper lip. At the angles of the extremity of
the middle frontal process are two slight lobes, the internal nasal processes of
Kolliker ; above these are two notches, the rudimentary nostrils, and between the
nostrils and eyes another pair of lobes, the external nasal processes of Kolliker, or
lateral frontal processes of Reichert. The maxillary lobe becomes united to the
internal and external nasal processes ; but between it and the latter there is left the
nasal duct. About the ninth week the inferior parts of the maxillary lobes, having
sent projections inwards, are united in the middle line and form the palate.
Fig. 56. A. MAGNIFIED VIEW FROM BEFORE OF THE HEAD
AND NECK OF A HUMAN EMBRYO OF ABOUT THREE WEEKS
(from Ecker, Icones Physiol. Tab. xxix. fig. I.).
1, anterior cerebral vesicle or cerebrum ; 2, middle ditto ;
3, middle or naso-frontal process ; 4, superior maxillary pro-
cess ; 5, eye ; 6, inferior maxillary process or first visceral
arch, and below it the first cleft ; 7, 8, 9, second, third, and
fourth arches and clefts.
B. ANTERIOR VIEW OF THE HEAD OF A HUMAN Forrus OF
ABOUT THE FIFTH WEEK (from Ecker, as before, fig. IV.).
1, 2, 3, 5, the same parts as in A ; 4, the external nasal
or lateral frontal process ; 6, the superior maxillary process ;
7, the lower jaw ; x , the tongue ; 8, first branchial cleft
becoming the meatus auditorius externus.
Formation of the cranium. The chorda dorsalis passes
into the base of the skull, as far forwards as the sphe-
noidal region. According to the observations of H. Muller
on the calf (Ueber das Vorkommen von Chordaresten, &c.,
in Zeitschr. fur Rat. Med. 3rd series, vol. ii.), it extends
from the odontoid process of the axis through the basilar
process of the occipital bone to the b#ck of the dorsum
sellse, which it pierces, and is lost behind the pituitary
body. Before attaining the osseous state, the cranium passes
through a membranous and cartilaginous condition, in which
it is termed the primordial cranium. In the membranous
cranium, the blastema, immediately beyond the extremity of the chor4a dorsalis,
presents two thick bars, the lateral trabeculce of Rathke, with a very thin part
in the middle line between them, corresponding to the position of the pituitary
body (see fig. 57, 4). These trabeculse unite in front in the ethmoidal region, and it is
to be remarked that in the cartilaginous stage the ethmo-vomerine cartilage or mesial
septum of the nose is continued directly forwards from the region containing the
chorda dorsalis. In the cartilaginous stage of the cranium the cartilage can only be
traced in the basilar parts, and corresponds in extent to the occipital bone below the
level of its protuberance, the petrous and mastoid portions of the temporal bone, the
sphenoid and the ethmoid, while the part of the wall in which the frontal and parietal
bones, the upper part of the occipital, and the squamous portions of the temporals
appear, remains membranous. The extent, however, over which the cartilage of the
primordial cranium extends differs in different animals, and is greater in many
mammals than in man (Kolliker). The nasal bones are derived from the middle
66
BONES OF THE HEAD.
frontal process, the superior maxillaries from the maxillary lobes, and the lachrymals
probably from the lateral frontal lobes.
Fig. 57.
Fig. 58.
Fig. 57. THE LOWER OR CARTILAGINOUS PART OF
THE CRANIUM OP A CHICK ON THE SIXTH DAY
(from Huxley, Elements of Compar. Anat. Fig.
57, F').
1, 1, chorda dorsalis ; 2, the shaded portion here
and forwards is the cartilage of the base of the skull ;
at 2 the occipital part ; at 3 the prolongations of
cartilage into the anterior part of the skull called
trabeculce cranii; 4, the pituitary space; 5, parts of
the labyrinth.
Formation of the face. In studying the early
development of the bones of the face it is necessary
likewise to take into consideration the ossicles of
the ear, viz., the malleus, incus, and stapes ; for al-
though in the adult these ossicles are so minute, and
Fig. 58. VIEW FROM BELOW OF THE CARTI-
LAGINOUS BASE OF THE CRANIUM WITH ITS
OSSIFIO CENTRES OF A HUMAN FOSTUS EIGHT
INCHES LONG (about five months, from Hux-
ley, as before, Fig. 59, slightly altered, the
bone being dotted to distinguish it from the
cartilage, which is shaded with lines).
1, the basilar part, 2, the condyloid or
lateral parts, and 3, 4, the tabular or superior
part of the occipital surrounding the foramen
magnum ; 5, centres of the pre-sphenoid on the
inside of the optic foramen ; 6, centres of the
post-sphenoid; 7, centres of the lesser wings
or orbito-sphenoid ; 8, septal cartilage of the
nose ; 9 & ] parts of the labyrinth .
Vmjg so entirely contained within the cavity of the
tympanum that they have not been included
4 in the description of the skull, they are im-
portantly connected in their origin with a
number of other bones. In each of the first three visceral arches a strip of firm tissue,
which becomes cartilaginous, appears. That of the first arch is the most perfect, and
is divided into three parts : the proximal part passes forwards some distance in
contact with the basis cranii, it becomes ossified without passing through a cartilagi-
nous stage, and from it are developed the palate bone and internal pterygoid plate ;
the middle part, which is very small, forms the body of the incus, and gives off two
processes, the long and short processes of that ossicle ; the remaining part, much the
largest of the three, is prolonged downwards to meet its fellow of the opposite side at
the extremity of the arch, and is named MecM's cartilage after its first describer.
(Meckel, " Handbuch der Mensch. Anat.") The upper extremity of Meckel's carti-
lage forms the malleus, the handle of which is developed as a process directed back-
wards. The lower portion is destined ultimately to dwindle away, but in the first
instance increases in size, and forms a rod. on the external surface of which the
lower jaw is formed. It can be detected on the internal aspect of the ramus of the
jaw, up to the eighth month of foetal life, but its only permanent vestige is the processus
gracilis of the malleus, which, when the tympanic cavity becomes closed inferiorly by
the growth of the tympanic plate, remains with its extremity fixed in the fissure of
Glaser. The proximal extremity of the cartilage of the second visceral arch forms
the stapes, and in succession downwards from this are found the stapedius muscle,
the styloid process of the temporal bone, the stylo-hyoid ligament, and the small
cornu of the hyoid bone. The only permanent portions of the cartilage of the third
visceral arch are the great cornu and the body of the hyoid bone. (Reichert " Ueber
OSSIFICATION OF CRANIAL BONES.
67
die Visceralbogen," Muller's Archiv, 1837. See for a figure of Meckel's cartilage the
description of the bssicles of the ear, under the Organs of the Senses.)
OSSIFICATION. The occipital bone, for some time after birth, consists of four sepa-
rate pieces, a basilar, a tabular, and two condyloid parts. The lines of junction of the
Fig. 59. OSSIFICATION OP THE
OCCIPITAL BONE.
A, in a foetus of 10 weeks
(from Meckel, Archiv, vol. i.
tab. vi.); a, upper or tabular
part ; 1 & 2, lower and upper
pairs of ossific centres in it ;
b, lower part or basilar and
condyloid portions : ossific cen-
tres are seen in the coudyloid
portions.
B, occipital bone of a child
at birth; a, upper or tabular
part, in which the four centres
have become united into one,
leaving fissures between them ;
6, 6, the ossified condyloid por-
tions ; c, the basilar portion.
Fig. 59.
basilar and condyloid parts pass through the condyles near their anterior extremities ;
those of the condyloid and tabular parts extend outwards from the posterior extremity
of the foramen magnum. The basilar. and condyloid parts arise each from one osseous
nucleus. In the tabular part there are probably in most cases four nuclei, placed in
pairs above and below the occipital protuberance : Meckel mentions four additional
nuclei, placed two at the superior and one at each lateral angle (" Handbuch der
Mensch. Anat.," ii. 543) ; the different nuclei speedily unite to form a single thin
tabular mass.
The parietal bones are ossified each from one nucleus which is placed near the
centre of the bone or at the parietal eminence.
The frontal bone consists for a year, or from one to two years after birth, of two
lateral portions, which not unfrequently remain separate during life (as happens also
Fig. 60.
Fig. 60. FRONTAL BONE OP A FCKTUS SHORTLY
BEFORE BIRTH.
a & 6 indicate the two separate portions
of the bone, in each of which the radiation
of bony spicula from the frontal eminence
is seen.
in the majority of animals), with a vertical
suture between them, the frontal suture.
Ossification begins on each side from a
single nucleus above the orbit, or in the
place of the frontal eminence.
The Fontanelles. Opposites the angles of
the parietal bones, there are spaces which
remain unoccupied by bone, after the osseous wall of the skull is elsewhere completed.
Two of these, the anterior and posterior fontanelles, are in the middle line ; the
lateral fontanelles, two on each side, are opposite the inferior angles of the parietal
bones, and are less important. The anterior fontanelle, situated between the adjacent
angles of the parietal bones and the ununited halves of the frontal bone, is quadran-
gular in form, and remains open for some time after birth. The posterior fontanelle,
situated between the parietal bones and the superior angle of the occipital bone, is
triangular ; it is filled up before birth, but during parturition the compression of the
child's head forces the angle of the occipital bone beneath the edges of the parietals,
F 2
68
BONES OF THE HEAD.
and produces a triangular depression at the site of the posterior fontanelle, which is
easily recognised by the finger of the accoucheur.
The temporal bone, considered in respect of its development, consists of the
squamous and petro-mastoid parts, the tympanic plate, and the styloid process. The
squamous part, inclusive of the zygomatic process, is ossified from a single nucleus.
The petrous and mastoid portions are also formed from only one centre : bone is first
deposited on the anterior surface, over the cochlea, and there afterwards appear one
or two nuclei on the posterior surface, in connection with the formation of the
semicircular canals ; the different nuclei soon unite, and ossification extends into
the mastoid process. The tympanic plate appears in the membranous wall of the
tympanum and external ear as a slender arch of bone forming three-fourths of a ring,
inclosing the membrana tympani. The styloid process is formed, as already stated,
in the second visceral arch.
Fig. 61. Fig. 61. SEPARATE PARTS OF THE TEMPORAL BONE
OF A CHILD AT BIRTH.
a, squamous part with the zygoma; b, the tym-
panic bone forming an imperfect ring open superiorly ;
c, the petrous and mastoid part ; c being placed on
the mastoid part : part of the cavity shown is the
tympanum.
The sphenoid bone presents in infancy traces
of a natural division into a posterior or post-
sphenoid part, to which the sella turcica and great
wings belong, and an anterior or pre-sphenoid part,
to which belong the body in front of the olivary
process and the small wings, a division which is
found in many animals complete and persistent
through life. The first osseous nuclei of the post-
sphenoid division occur in the great wings, one on
each side, between the foramen rotundum and
foramen ovale, and spread thence outwards into the wing and downwards into the
external pterygoid process. The internal pterygoid processes arise from distinct
nuclei, and, although in the human subject they soon unite with the external
pterygoid, in other animals they remain separate, and are named by comparative
anatomists the pterygoid bones.
Fig. 62.
Fig. 62. OSSIFICATION OF THE SPHENOID BONE.
A, sphenoid bone from, a foetus of three months, seen from above; 1,1', the greater
wings ossified ; 2, 2, the lesser wings, in which the ossification has encircled the optic
foramen, and a small suture is distinguishable at its posterior and inner side; 3, two
round granules of bones iu the body below the sella turcica, the rest being cartilaginous.
B, copied from Meckel (Archiv, vol. i. tab. vi. fig. 23), and stated to be from a foetus
OSSIFICATION OF FACIAL BONES.
G9
of six months ; 2*, additional nuclei for the lesser wings ; 5, separate lateral processes
of the body : the other indications are the same as in A.
C, sketch of the back part of the bone shown in A ; 4, the internal pterygoid processes
still separate.
D, the sphenoid at the usual period of birth. The great wings are still separate.
The anterior sphenoid is now joined to the body, and the internal pterygoid processes
(not seen in the figure) are united to the external.
In the post-sphenoid part of the body two granules appear, placed side by side in
the sella turcica, and after their union two others appear, from which are formed
the parts on which are placed the carotid grooves. In the pre-sphenoid division the
first pair of nuclei appear outside the optic foramina, and extend by their growth into
the small wings : another pair of granules appear on the inner sides of the foramina,
and the pre-sphenoid portion of the body either results from the union of these, or
is an independent growth. The pre-sphenoid is united to the body of the post-
sphenoid long before the latter is united to the great wings. Their line of union is
indicated for some time by a hole filled with cartilage, round above, and opening
inferiorly into a wide notch, which is recognisable for several years after birth. The
body of the pre-sphenoid is for a year or two broad and rounded inferiorly, but
becomes gradually narrower and more prominent : it is separated at first by a layer of
fibro-cartilage from the sphenoidal spongy bones. The sphenoidal spongy bones
seldom appear till after birth : each is in early life a hollow pyramid formed by the
union of three separate laminae, viz., an inferior, an external, and a superior : the
inferior lamina forms the greater part of what can be distinguished in the adult ;
the external is that to which the orbital portion belongs ; while the superior lamina,
forming the inner wall and roof of the original sphenoidal sinus, becomes, as the
sinus expands, partly absorbed and partly united to the attenuated body of the pre-
sphenoid, which is ultimately reduced to the thin septum sphenoidale and the
rostrum.
The ethmoid bone exhibits osseous deposit first in the orbital plates, whence it
spreads into the turbinated portions ; in its mesial part ossification begins above
and passes down into the nasal septum, and outwards into the cribriform plate.
The superior maxillary bone commences to ossify at a very early period imme-
diately after the lower maxilla and the clavicle, and before the vertebrae. Its early
growth has not yet been sufficiently studied. Beclard (Meckel's Archiv., vi. p. 432)
Fig. 63. DIFFERENT VIEWS OF THE SUPERIOR MAXILLARY BONE OF A FOSTUS OF FOUR
OR FIVE MONTHS.
A, external surface ; a fissure, 1, is seen extending through the orbit into the infra-
orbital foramen.
B, the internal surface ; the incisor fissure, 2, extends from the foramen upwards
through the horizontal plate and some way into the nasal process.
C, the bone from below, showing the imperfect alveoli and the incisor fissure, 2', 1,
which crosses the palatine plate, between the second and third alveolus, and passes
through the outer part of the bone.
states that it consists at first of five pieces, viz., 1, an alveolar arch ; 2, a palatal part;
3, an orbital and malar ; 4, a nasal and facial ; 5, an incisor part. This, however,
does not appear to be a constant arrangement. In all young subjects, and sometimes
even in the adult, there is a fissure, the incisor fissure, passing outwards from the
incisor foramen to the alveolar border, in front of the canine socket. The part in
70 BONES OF THE HEAD.
front of this fissure namely, that which bears the incisor teeth forms in all
mammals except man a separate bone, the intermaxillary or premaxillary ; and
anatomists have therefore sought with great care for proofs of its original independence
in the human subject, but it does not appear that even in the earliest stages of develop-
ment it has been seen by any one entirely unattached to the rest of the bone, or that
its line of suture has been traced upon the facial surface. On the other hand, in
cases of completely cleft palate, the bones supporting the incisor teeth are placed on
a projecting portion of bone, which is articulated to the fore part of the vomer, and
is entirely detached from the superior maxillary bones.
The palate bone is formed from a single centre, which is deposited at the angle
between its horizontal and ascending parts.
Fig. 64. Fig. 64. THE F(ETAL VOMER NEAR THE TIME OF BIRTH.
1 & 2 show the two plates of which the bone consists, and
which are united behind and below.
The vomer begins to ossify posteriorly near the upper part.
It consists at first of two laminas united posteriorly and
inferiorly. The inferior border afterwards exhibits a flat surface marked by a mesial
line, which articulates with the maxillary and palate bones and ends abruptly behind
the crista nasalis. The margins of this surface become gradually absorbed. The ap-
pearance of a mesial plate does not take place for a little time after birth.
The malar, nasal, lachrymal, and inferior turbinated bones are each ossified from a
single centre.
Fig. 65. Fig. 65. THE INFERIOR MAXILLA OF A
CHILD AT BIRTH.
a & 5 indicate the two portions separate
at the sympbysis.
The inferior maxilla begins to ossify be-
fore any other bone except the clavicle. It
consists of two equal lateral parts, which
are still separate at the time of birth. The
ossific matter is at first deposited in fibrous
tissue, and later in cartilage. Some ob-
servers admit only a single ossific centre
for each side (Nesbitt and Meckel) ; while,
according to others, in addition to the main piece there are separate nuclei for the
coronoid process, the condyle, the angle, and the inner side of the alveolus (Spix),
or only for some of these parts (Kerckringius, Be"clard, Cruveilhier). The dental canal
is at first a simple open groove. As in the superior maxilla the alveoli are gradually
developed from the groove by its division into compartments by partitions of subse-
quent growth.
The hyoid bone has five points of ossification one for the body, and one for each
of its great and small cornua. The ossification begins in the great cornua, and soon
follows in the body in the last month of foetal life.
PERIODS OF OSSIFICATION OF THE BONES OF THE SKULL.
In the occipital bone
Ossification of the tabular part appears in the 7th week (foetal life).
Ossification of the basilar part appears in the 7th or 8th week.
Ossification of the condyloid part appears in the 7th or 8th week.
The condyloid and tabular parts unite in the 4th year.
The basilar and condyloid parts unite in the 5th or 6th year.
In the parietal bone ossification appears in the 7th or 8th week.
In the frontal bone ossification appears in the 7th week.
The parts of the frontal bone unite in the course of the 2nd year.
THE SKULL IN GENERAL. 71
In the temporal bones
Ossification of the squamous part appears in the 7th or 8th week.
Ossification of the petro-mastoid part appears in the 4th month.
Ossification of the ossicula auditoria appears in the 4th month.
Ossification of the tympanic ring appears in the 3rd month.
Ossification of the styloid process appears after puberty.
The tympanic ring unites with the squamous part at birth.
The squamous and petro-mastoid parts unite in the 1st year.
In the sphenoid bone
Ossification of the great wings appears in the 8th week.
Ossification of the posterior part of the body appears in the 8th or 9th week.
Ossification of the internal pterygoid processes appears in the 4th month.
Ossification of the anterior part of the body, including the small wings, appears
in the 8th or 9th week.
Ossification of the sphenoidal spongy bones appears about the time of birth.
The centres of the posterior part of the body unite in the 4th month.
The internal and external pterygoid processes unite in the 5th or 6th month.
The anterior and posterior parts of the body unite in the 8th month.
The body and great wings unite in the 1st year.
The sphenoidal spongy bones and the body unite about the age of puberty.
In the ethmoid bone
Ossification of the lateral masses appears in the 4th or 5th month.
Ossification of the vertical and cribriform plates appears in the 1st year.
In the superior maxillary bones ossification appears in the 6th or 7th week.
In the palate, vomer, nasal, and malar bones ossification appears in the 7th or
8th week.
In the lachrymal bones ossification appears in the 8th week.
In the inferior turbinated bones ossification appears in the 5th month.
In the inferior maxillary bone ossification appears in the 6th week.
The two parts of the inferior maxillary bone unite in the 1st year.
In the hyoid bone
Ossification of the body and great cornua appears before birth.
Ossification of the small cornua appears in the 1st year.
THE VERTEBRAL THEORY OP THE SKULL.
The idea that the skull is composed of a series of vertebrae, whose arches are expanded
and united to enclose and protect the encephalon, appears to have originated with
Goethe in 1791, but occurred independently to Oken, and was first published by him
in 1 807. Since then many conflicting theories have been brought forward on the subject
by different anatomists, who have estimated the cranial vertebrae at numbers varying
from three to seven ; while by others the idea has been entirely rejected, and even
the possibility of referring the bones of the skull to distinct segments denied. Some
of the facts in favour of the vertebral theory are sufficiently manifest. Thus, the
basilar process of the occipital bone, and the mesial parts of the post-sphenoid and
pre-sphenoid bones, lie in series with and bear considerable resemblance to the centra
or bodies of vertebrae, as is seen particularly in those animals in which the pre-
sphenoid and post-sphenoid bones remain distinct : the visceral arches of the embryo
likewise form a series : in the roof of the skull a certain degree of repetition of parts
from behind forwards is also visible, especially in some of the lower animals : the
mode of formation of the head and of the trunk is almost the same up to the time
when the primordial vertebrae appear in the latter : and lastly, the general resem-
blance of the occipital bone to a vertebra is admitted by all. On the other hand, it
must be allowed that there is no original division of the cartilaginous basis of the
cranium ; in that part of it which lies in front of the sphenoid bone, and to which
the chorda dorealis does not penetrate, it is not easy to trace a resemblance to vertebral
form ; and in the face it is still more difficult to demonstrate in the several parts a
definite arrangement of visceral or costal arches. Deterred by the differences of opinion
with respect to the number of cranial segments and the bones which belong to each,
some may be inclined to set aside the discussion entirely, but we must not too rashly
decide against the existence of such segmentation, nor forget that some correspondence
72 BONES OF THE HEAD.
between several bones of the skull and vertebrae in man and animals is generally ad-
mitted by scientific anatomists, and that the difficulties which oppose the enunciation
of clearer views on the serial relations of the cranial elements arise in great measure
from deficient information and want of agreement among anatomists as to individual
points in the correspondence of those elements throughout the animal series. (See,
in addition to the works previously referred to, Huxley, " Elements of Comparative
Anatomy," 1864 ; Cleland, " On the Relations of the Vomer," &c., Trans. Hoy. Soc.
1862; Spix, " Cephalogenesis," 1815; Von Baer, " Entwickelungsgesch. der Thiere,"
182837 ; Hallcuan, " Die Vergleich. Anat. des Schlafenbeins," 1837 ; Bojanus in
Isis, 18181819.)
THE VARIOUS FORMS OF THE SKULL.
I. Differences according to Age. In the earlier stages of its development the posterior
part of the skull bears a very large proportion to the anterior part; so much so, that
in the second month of foetal life the line of the tentorium cerebelli is vertical to the
basis cranii, and divides the cranial cavity almost equally into two parts. At th6 time
of birth the parietal region has reached its largest development in proportion to the
occipital and frontal regions. The greatest frontal breadth is then smaller in pro-
portion to that between the parietal eminences than afterwards. In the first years
of childhood the superior parts of the skull grow more rapidly than the base. Thus,
in the frontal region, the upper part of the frontal bone grows more rapidly than its
orbital processes, giving the prominent appearance of the frontal eminences peculiar
to children. The face at birth is calculated as being scarcely an eighth of the bulk
of the rest of the head, while in the adult it is at least a half (Froriep, " Characteristik
des Kopfes nach dem Entwicklungsgesetz desselben "). In harmony with the growth
of the face the lower part of the forehead is brought forward by elongation of the
anterior cranial fossa, and on the approach of adult age it becomes in the male still
more prominent by the expansion of the frontal sinuses. The face becomes elongated
in the progress of growth, partly by increased height of the nasal fossae, partly by
the growth of the teeth and the enlargement of the alveolar arches of the jaws. In
old age the proportion of the face to the cranium is diminished by the loss of the
teeth and absorption of the alveolar portions of the jaws. In consequence of this the
upper jaw retreats, while in the lower jaw the same cause gives, especially when the
mouth is closed, a greater seeming prominence to the chin.
II. Sexual Differences. The female skull is, in general, smaller, lighter, and smoother
than that of the male ; it is less marked by muscular prominences, and has also the
frontal sinus less developed. The face is smaller in proportion to the cranium, the jaws
narrower, and the frontal and occipital regions less capacious in proportion to the
parietal. (Huschke.) The female skull resembles the formed skull of the boy more
than that of the adult male ; but it must also be admitted that it is often impossible
to determine the sex by the appearance or form of a skull.
III. National Differences. That characteristic forms of skull are presented by the
various races of men has probably been long known, but was first distinctly pointed
out by Camper. Subsequently the investigations of Blumenbach raised the study of
those different forms to a recognised position in ethnology. The extent and constancy
of the ethnical differences of skulls are matters open to discussion ; but it must be
allowed, that although many skulls are to be met with which fail to exhibit the
characteristics of the race to which they belong, or which present peculiarities similar
to those of nations considerably removed from them, yet not only are there certain
forms of skull highly distinctive of the principal varieties of mankind, but the pre-
vailing form in one nation is often very distinguishable from those found in nations
inhabiting neighbouring countries. Great differences occur with respect to size in
the skulls of different nations. Among the smallest skulls may be .mentioned those
of the Hindoo and ancient Peruvian ; among the most massive those of the Scandi-
navian, the Caffre, and the Maori. Various characters are found belonging to the
skulls of rude tribes, which serve to distinguish them from those of civilised nations.
Among those characters may be mentioned, a depressed appearance between the
middle line of the calvarium and the temporal ridge, both of which stand out promi-
nently, making the roof of the skull seem like a house-top ; a greater width of the
zygomatic arches, and of the anterior nares ; greater strength of the jaws and teeth,
THE SKULL IN GENERAL. 73
and especially projection forwards of the incisors, so that those of the upper meet
those of the lower jaw at an angle, instead of both sets being nearly perpendicular
as in cultivated nations. Elongation of the face downwards may be regarded as a
specially human characteristic connected with the use of voice and speech, but projec-
tion of the jaws forwards is only advantageous for the seizure of food, and gives an
appearance of approach to the still further projected form of the jaws in the lower
animals, particularly when accompanied, as it often is, by deficient development of
the chin.
The degree of projection of the face in different races of men, and its prominence
and increased proportion to the cranium in the lower animals, Camper proposed
to express by the angle contained between two lines, one of them descending from
the most prominent part of the forehead to the incisor margin of the upper jaw, the
other passing through the meatus auditorius externus and the nasal spine : this he
termed the facial angle. He estimated its maximum in the European adult at 80,
and in the skull of a young negro he found it diminished to 70 ; while in antique
works of art he pointed out that it was increased for artistic effect to 90 or more,
an extent never realised in nature. In animals, the facial angle is always much
lower than in man. According to Camper and Lawrence, it reaches in the young
orang as high a point as 56 or 60 ; but in the adult orang they found it attaining
only to 47, while Owen finds it to be as low as 30. (Owen, " Zoolog. Trans.,"
vol. i. p. 373.) Several modifications of Camper's angle have been suggested ; but,
like it, they all labour under the disadvantage of being subject to modification from
other peculiarities besides the relations proposed to be estimated.
A convenient method of comparing the skulls of different races was introduced
by Blumenbach, and has been much employed, the norma verticalis, or examination
of the skull by looking perpendicularly down upon it, which exhibits in one view the
proportionate length and breadth of the cranium, the projection of the jaw beyond
the forehead, and the lateral prominence of the zygomatic arches. In addition to
the norma verticalis and profile view, Prichard has likewise employed the front view
in examining skulls, showing that, whereas, in well-formed European heads, lines
drawn from the zygomatic arch and touching the temples are parallel, the same lines
in the skulls of Esquimaux and others meet over the forehead, and form with the
basis a triangular figure.
More recently, a classification of skulls has been made by Retzius, which has
met with considerable acceptance. According to his arrangement, they may be
primarily divided into the dolichocephalic, or those which are elongated from before
backwards, and the brachycephalic, or those which have nearly as great breadth as
they have length. In each of those divisions are distinguished the prognathous skulls,
or those in which the upper jaw is visible when they are examined by the norma
verticalis, and the orthognathous, in which the jaw is overhung by the forehead. The
nations of Western Europe present the orthognathous dolichocephalic type of skull ; the
African negro the prognathous dolichocephalic type ; the Slavonic nations exhibit the
orthognathous brachycephalic type ; the Mongolians the prognathous brachycephalic.
(Camper, " On the Connection between Anatomy, Drawing, &c.," transl. by Cogan,
1794 ; Blumenbach, ""Institutions of Physiology," by Elliotson, 1820; and "De Generis
Humani Varietate Nativ&,"3rd edition, 1795; Prichard, " Researches into the Physical
History of Mankind," and "Natural History of Man; " Morton, " Crania Americana;"
Thurnam and Davies, " Crania Britannica ; " Huschke, " Schadel, Him, und Seele
des Menschen und der Thiere, &c,," 1854 ; Meigs, " Cranial Characteristics otthe Races
of Men," Philad. 1857 ; Retzius, " On the present State of Ethnology with reference
to the Form of the Skull," translated in Brit, and For. Medico-Chir. Review, April &
July, 1860 ; Carpenter, in " Cyclop, of Anat. and Physiol.")
IV. Irregularities of Form. The most frequent irregularity in the form of the
skull is want of symmetry. This sometimes occurs in a marked degree, and there is
probably no skull perfectly symmetrical. The condition which has been observed to
co-exist most frequently with irregular forms of skull is synostosis, or premature
obliteration of certain of the sutures. The cranial bones increase in size principally
at their margins ; and when a suture is prematurely obliterated, the growth of the
skull in the direction at right angles to the line of suture may be supposed to be
checked, and increased growth in other directions may take place to supply the defect.
74 BONES OF THE UPPEK LIMB.
(For an account of the varieties of form thus produced, see Virchow, " Gesammelte
Abhandlungen," 1856.) Another series of irregular forms of skull is that produced
by pressure artificially applied in early life, and is best exemplified from among
those American tribes who compress the heads of their children by means of an
apparatus of boards and bandages : it is also illustrated in a slighter degree by
individual instances in which undue pressure has been employed unintentionally.
(Gosse, "Essai. BUT les Deformations artificielles du Crane," 1855.) Posthumous
distortions likewise occur in long-buried skulls, subjected to the combined influence
of pressure and moisture. (Wilson, " Prehistoric Annals of Scotland.")
IV. BONES OF THE UPPER LIMB.
The superior extremity, or upper limb, consists of the shoulder, the arm,
the fore arm, and the hand. The bones of the shoulder are the scapula and
clavicle ; in the arm is the humerus ; in the fore arm are the radius and
ulna ; and ID the hand three groups of bones, the carpus, metacarpus, and
digital phalanges,
SCAPULA.
This bone is placed upon the upper and back part of the thorax, occupies
the space from the second to the seventh rib, and forms the posterior part of
the shoulder.
It is attached directly to the trunk only by the clavicle, and from it is
suspended the humerus.
It is of an irregular triangular form, flat in the greater part of its extent,
and elongated downwards ; and is so placed, that its internal border is like-
wise posterior. Its angles may be termed superior, inferior, and external.
It has an anterior and posterior surface, and presents at its external
angle the head with its glenoid cavity or articular surface for the humerus,
supported on a short thick neck of bone, and surmounted by the coracoid
process ; also, springing from its posterior surface, the spine terminating in
the acromion process.
The anterior surface exhibits in the greater part of its extent a shallow
concavity, the fossa subscapularis or venter, occupied by the subscapularis
muscle, and marked by irregular prominent lines converging upwards and
outwards, which give attachment to the tendinous intersections of that
muscle. Separated, however, from this concavity, there are several smaller
flat spaces : one is a triangular surface in front of the superior angle,
another is a smaller surface at the inferior angle, and these, together with a
rough line running close to the posterior border and uniting them, give
attachment to the serratus magnus muscle : there is also a grooved area
occupied by the lower border of the subscapularis muscle, close to the ex-
ternal border, and separated from the fossa subscapularis by a prominent
ridge descending from the neck of the bone.
The posterior surface or dorsum is divided by the spine into two unequal
parts, the superior and smaller of which is called fossa supraspinata, the in-
ferior fossa infraspinata. The supraspinous fossa has its greatest vertical
extent at its internal extremity, but is deepest externally : it is occupied by
the supra-spinatus muscle. The infraspinous fossa, much larger than the
preceding, presents in the middle a convexity corresponding to the concavity
of the venter, and outside this a concavity bounded by the prominent
external border. It is marked near the inner border by short lines, cor-
responding to tendinous septa of the infraspinatus muscle, and is occupied
by that muscle in the greater part of its extent. Adjacent to the external
border, in its middle third, is a narrow inteival giving attachment to the
SCAPULA.
teres minor muscle ; and beneath this, extending over the inferior angle, is
a raised oval surface, from which the teres major arises. These spaces are
separated from that of the infraspinatus muscle by a rough line, which
gives attachment to an aponeurotic septum.
The spine of the scapula is a massive plate of bone projecting backwards
from the dorsurn, and curving slightly upwards. It extends outwards and
Fig. 66. Fig. 67.
2
6
Fig. 66. RIGHT SCAPULA FROM BEHIND. |
1, glenoid head ; 2, superior angle ; 3, inferior angle ; 4, spine ; 4, at the base, points
by a line to the triangular smooth surface of the spine ; 5, acromion ; 6, coracoid process ;
7, supraspinous fossa; 7', infraspinous fossa; 1 to 2, superior border; 2 to 3, posterior
border or base ; 1 to 3, external or inferior border ; 10, is opposite the oval surface of
origin of the teres major muscle ; 11, the oblique groove where the teres minor muscle
rises; 12, the rough ridge where the long head of the triceps rises; 13, supra-scapular
notch ; 14, is below the great scapular notch.
Fig. 67. RIGHT SCAPULA FROM BEFORE. ^
1, 5, 6, & 13, as in fig. 66; 5', articular facet on the acromion for the clavicle;
8. subscapular fossa ; 9, long, narrow surface, and 9', triangular rough surface, separated
from the subscapular fossa and giving attachment to the upper and lower parts of the
serratus magnus muscle.
a little upwards from the internal border near its upper fourth, towards the
middle of the neck, and becoming gradually elevated towards its external
extremity, it turns forwards and is continued into the acromion process.
The upper and lower surfaces are smooth, of a triangular form, concave,
and form part respectively of the supra-spinous and infra-spinous fossae.
It presents two unattached borders, the most prominent of which arises
from the internal border of the bone by a smooth, flat, triangular surface,
on which the tendon of the inferior part of the trapezius muscle glides,
as it passes to be inserted into a rough thickening beyond, which projects
slightly downwards. In the rest of its extent this border is rough, broad,
and subcutaneous, giving attachment by its superior margin to the trapezius,
and by its inferior to the deltoid muscle. The other, the external border,
short, smooth, and concave, arises near the neck of the scapula, and is con-
tinuous with the under surface of the acromion, surrounding thus the great
scapular notch between the spine and the neck of the bone.
76 BONES OF THE UPPER LIMB.
The acromion process, projecting outwards and forwards from the extremity
of the spine, is situated above and behind the glenoid cavity, and forms the
summit of the shoulder. It is an expanded process, compressed from above
downwards. Its superior surface, rough and subcutaneous, is continuous
with the prominent border of the spine ; its inferior surface, smooth and
concave, is continuous with the superior surface and external border of the
spine. On its internal border anteriorly is a narrow oval surface for articula-
tion with the clavicle ; and at its extremity it affords attachment to the
coraco-acromial ligament.
The glenoid cavity is a slightly concave surface, looking outwards and a
little upwards and forwards. It is ovoid or rather pyriform in shape, with
the narrow end uppermost, and gently incurved in front. It is in some
degree flattened at its circumference, where, in the recent state, it is covered
by a fibrous band, the gleuoid ligament, which deepens its concavity ; and
at its upper extremity is a slight roughness, marking the attachment of the
long head of the biceps muscle.
The neck, supporting the glenoid cavity, is most distinct posteriorly, where
it forms between the glenoid cavity and the spine the great scapular notch or
groove, leading from the supraspinous to the infraspinous fossa. The line
of the neck, as described by anatomists, passes superiorly between the glenoid
cavity and the coracoid process, but that of the part often named neck by
surgeons passes internal to the coracoid process.
The coracoid process, thick and strong, springs almost vertically from the
superior border of the bone, above the glenoid cavity, but, suddenly
bending at a right angle, is directed forwards and outwards. Its superior
surface, towards the base, is rough and uneven, giving origin to the corac'o-
clavicular ligaments ; on its outer border is attached the coraco-acromial
ligament, at its extremity the coraco-brachialis muscle and short head of
the biceps, and on the inner edge the pectoralis minor.
The borders or costce of the scapula are three in number. The superior
border is the shortest ; it extends from the superior angle outwards and down-
wards towards the coracoid process, at the base of which it presents a rounded
suprascapular notch (incisuta semilunaris), which is converted into a foramen
by a ligament or occasionally a spiculum of bone, and is traversed by the
suprascapular nerve, and sometimes also by the accompanying vessels. The
external, axillary, or inferior border presents at its upper part, beneath the
glenoid cavity, a rough tuberculated ridge, above an inch long, to which the
long head of the triceps muscle is attached : a little below this there is
usually a slight groove, where the dorsal branch of the subscapular artery
passes backwards : and at its lower extremity the border is thick, and
rounded over into the space from which the teres major muscle arises. The
internal, vertebral, or posterior border, called also the base, is the longest of
the three, and is divisible into three parts, viz., a short one opposite the
triangular surface of origin of the prominent border of the spine, and the
portions above and below that space, both of which incline outwards as they
recede from the spine. The upper part gives attachment to the levator
anguli scapulae muscle, the middle one to the rhomboideus minor, and the
lower to the rhomboideus major muscle.
Texture. The triangular part of the scapula is in great part thin and
translucent, and contains little cancellated tissue. The neck, the coracoid
and acromion processes, the prominent border of the spine, and the part
near the inferior angle, derive their greater thickness and strength from
increased thickness of the compact bony substance in some parts, and
CLAVICLE.
77
from cancellated tissue in others. A vascular foramen usually pierces the
inferior surface of the spine, and others are to be found on the anterior
surface of the bone, near the neck.
THE CLAVICLE.
The clavicle or collar-bone extends transversely outwards, with an inclina-
tion backwards, from the summit of the sternum to the acromion process of
the scapula, and connects the upper limb with the trunk.
It is curved somewhat like an italic /: the convexity of the internal
curve is directed forwards, and extends over two-thirds of the length of the
bone ; that of the outer curve looks backwards, and is most marked near the
outer fourth of the bone.
The clavicle, towards its scapular end, is compressed and broad from
above downwards, but in the extent of its inner curve it is more or less
prismatic or cylindrical. In its description, four surfaces of the shaft may
be distinguished, together with the two extremities.
Fig. 68. THE BIGHT Fig. 68.
CLAVICLE. ^
A, from above ; B, from
below.
1, sternal end ; 2, acromial
end ; 2', small facet for arti-
culation with the acromion ;
3, groove on the lower
surface for the subclavius
muscle ; 4, rough elevation
at the place of attachment
of the coraco-clavicular liga-
ments ; 5, rough depression
at the place of attachment
of the costo-clavicular or rhomboid ligament ; 6, in front, the mark of the attachment of
the pectoralis major ; 7, that of the deltoid muscle.
The superior surface is broadest in its outer part ; it is principally sub-
cutaneous, but near the inner extremity presents a slight roughness, marking
the clavicular attachment of the sterno-cleido-mastoid muscle. The anterior
surface opposite the outer curve is a mere rough border, from which the
deltoid muscle takes origin, but in the inner half of its extent is broadened
out into an uneven space more or less distinctly separated from the inferior
surface, and giving attachment to the pectoralis major muscle. The posterior
surface is broadest at the inner extremity, and smooth in the whole extent of
the internal curvature ; but towards its outer extremity it forms a narrow
rough border which separates it from the superior surface, and gives
attachment to the trapezius muscle. On the inferior surface an elongated
roughness near the scapular extremity marks the attachment of the coraco-
clavicular ligaments ; extending inwards from this, over the middle third of
the bone, is a groove in which the subclavius muscle is inserted ; and near
the sternal end is a smaller rough depression, to which the costo-clavicular
ligament is attached.
The internal extremity is the thickest part of the clavicle. It presents a
somewhat variably concavo-convex surface, somewhat triangular in form,
with its most prominent angle directed downwards and backwards. The
compressed external extremity is convex from before backwards, and articulates
by a small oval surface with the acromion.
78 BONES OF THE UPPER LIMB.
Texture. The interior of the clavicle contains coarse cancellated tissue
in its whole extent. It almost always presents a foramen for a medullary
artery on its posterior surface, and sometimes others.
THE HUMERUS.
The humerus or arm-bone extends from the scapula to the bones of the
forearm, with each of which it is articulated. It hangs nearly vertically
from the shoulder, with an inclination inwards towards the lower end. It
is divisible into a superior extremity, including the head, neck, and greater
and smaller tuberosities ; the shaft ; and the in-
Fig. 69. ferior extremity, including the external and internal
supracondyloid eminences, and the inferior articular
surface. In general form it is subcylindrical and
slightly twisted.
The superior extremity is the thickest part of
the bone. The . head is a large hemispherical
articular elevation, directed inwards, upwards, and
somewhat backwards. The neck, as described by
anatomists, is the ring of bone which supports the
head ; iuferiorly, it passes into the shaft ; superiorly,
it is a mere groove between the head and the great
tuberosity. The neck, as often described by sur-
geons, is the part of the shaft immediately below
the tuberosities. The great tuberosity is a thick
projection, continued upwards from the external
I ,;'| part of the shaft, and reaching nearly to the level
of the upper margin of the head ; it is sur-
mounted by three flat surfaces, the uppermost of
which gives attachment to the supraspinatus
muscle, the lowest to the teres minor, and the
intermediate one to the infraspinatus muscle.
Separated from the great tuberosity by the com'
mencement of the bicipital groove, the small
tuberosity, rounded and prominent, looks directly
forwards and gives attachment to the subscapularis
muscle.
Fig. 69. RIGHT HUMERUS PROM BEFORE.
1, the articular head ; 2, lesser tuberosity ; 3, greater
tuberosity ; 4, neck of anatomists ; 5, bicipital groove ;
6, inner bicipital ridge, and mark of the attachment of the
latissimus dorsi and teres major muscles; 7, outer bicipital
ridge, and rough surface of insertion of the pectoralis major,
running down into 7', the triangular mark of the insertion
of the deltoid ; 8, spiral groove ; 9, inner ridge of the
humerus; 10, trochlear articular surface; 11, capitellum,
or radial condyle ; 12, epitrochlear or internal supracondy-
loid eminence ; 13, capitellar or external supracondyloid
eminence; 14, coronoid depression or fossa.
iv
The shaft or body, thick and cylindrical supe-
riorly, becomes somewhat thinner as it descends, and in the lower third
is expanded transversely and becomes somewhat three-sided. Superiorly on
its anterior aspect is the bicipital groove, so named from lodging the long
HUMERUS.
79
tendon of the biceps muscle : this groove, commencing between the
tuberosities, descends with an inclination inwards, and is bounded by two
rough ridges, the external and most prominent of which gives attachment
to the pectoralis major muscle, the internal or posterior to the latissimus
dorsi and teres major. Towards the middle of the
shaft, on the inner lateral line, is a rough linear mark Fig. 70.
where the coraco-brachialis muscle is inserted, and
lower down there is a medullary foramen directed
downwards into the interior of the bone. On the
external part of the shaft, near its middle, in a line
anteriorly with the external bicipital ridge, is a large,
rough, and uneven surface, of a triangular shape, the
impression of the deltoid muscle. Below this the
external bicipital ridge is continued into a smooth
elevation which, descending on the front of the shaft
to the inferior extremity, separates an external from
an internal surface, while at the sides two sharp edges,
the external and internal supracondyloid ridges spring
from the eminences of the same name and ascend
for some distance, separating the anterior from the
flat posterior surface. About the middle of the
shaft externally, a broad depression, the musculo-spiral
groove, passes downwards and forwards in a spiral
direction, limited above by the deltoid impression
and below by the external supracondyloid ridge, and
lodges the musculo-spiral nerve and the accompanying
artery.
Fig. 70. RIGHT HUMERUS FROM BEHIND.
1, 3, 8, & 10, the same as in Fig. 69; 15, is placed above
the olecranon fossa,
The inferior extremity is much enlarged laterally,
flattened from before backwards, and is curved slightly
forwards. Projecting on either side are the external
and internal supracondyloid eminences (the condyles of
most authors, epicondyle and epitrochlea of Chaussier),
the internal of which is much more prominent than
the external, and is slightly inclined backwards. The
inferior articular surface, fitting by peculiar curved
grooves aud eminences to the corresponding surfaces
of the radius and ulna, is divided by a ridge into an
external and an internal part. The external part,
articulated with the radius, consists of a rounded eminence directed forwards,
called the capitellum, and a groove internal to it ; it does not extend to the
posterior surface. The internal part, the trochlea, articulates with the ulna,
and extends completely round from the anterior to the posterior surface of
the bone ; it is grooved down the middle like the surface of a pulley, and is
somewhat broader behind than in front ; anteriorly, its margins are inclined
downwards and inwards ; posteriorly, upwards and outwards, and so that seen
from behind, it lies in the middle part of the bone. Anteriorly, the internal
margin of the trochlea is the most prominent, and widens below into a
convexity parallel to the groove ; posteriorly, the external margin is most
80 BONES OF THE UPPER LIMB.
prominent. Above the trochlea posteriorly is a large and deep pit, the
olecranon fossa, which receives the olecranon process of the ulna in extension
of the forearm ; and above it anteriorly, separated from the olecranon fossa
only by a thin lamina of bone, is the much smaller coronoid fossa which
receives the coronoid process in flexion. Above the capitellum is a shallow
depression, into which the head of the radius is pressed in complete flexion.
Varieties. It is not uncommon to find a small hooklike process, with its point
directed downwards, placed in front of the internal supracondyloid ridge, the
supracondyloid process. From its extremity, a fibrous band, giving origin to the
pronator radii teres muscle, passes to the internal supracondyloid eminence, and
through the arch thus formed passes the median nerve, accompanied frequently by
the brachial artery, or by a large branch rising from it. This process represents a
portion of the bone completing a foramen in carnivorous animals. Much has been
written on the subject. (Struthers, Edin. Med. Journ. 1848. Gruber, " Canal is
supracondyloideus humeri," Mem. de 1'Acad. Imp. de St. Petersburg, 1859, p. 57.
Hyrtl, "Topogr. Anat." v. ii. p. 283.) The thin plate between the olecranon and
coronoid fossae is sometimes perforated.
THE RADIUS.*
The radius is the external of the two bones of the forearm, and extends
from the humerus to the carpus. It is thickest at its lower extremity.
It articulates with the humerus, the ulna, the scaphoid, and the semi-
lunar bones.
The head, or superior articular extremity, is of the form of a disc, with a
smooth vertical margin. It presents on its summit a depression, which
articulates with the capitellum of the humerus, and is surrounded by a
convex part, broadest internally where it glides upon the groove internal
to the capitellum. The smooth, short, cylindrical surface of the vertical
margin, likewise broadest internally, rolls on the small sigmoid cavity of the
ulna and within the orbicular ligament. The head is supported on a con-
stricted portion of a cylindrical form, named the neck.
The shaft or body is slightly curved, with the convexity directed outwards
and backwards. On its internal aspect superiorly, where it is continuous
with the neck, is the bicipital tuberosity, to the posterior border of
which is attached the tendon of the biceps muscle. Below the bicipital
tuberosity the shaft presents three sides, the external of which is rounded
into the others by smooth convex margins, while the anterior and posterior
surfaces are separated by an acute internal margin, which gives attachment
to the in terosseous ligament. The external surface is convex transversely as
well as longitudinally ; it is marked near the middle by an oval rough part,
about one inch and a half long, which gives insertion to the pronator radii
teres. The anterior surface is marked in its upper part by an oblique ridge,
below which is a shallow longitudinal groove for the flexor longus pollicis ;
inferiorly it is expanded, and presents a flat impression corresponding with
the pronator quadratus ; and above the middle is the foramen for the
medullary vessels, directed upwards into the bone. The posterior surface
presents slight oblique impressions of the extensor muscles of the thumb.
The lower extremity of the radius, broad and thick, and somewhat quadri-
lateral, presents inferiorly a large surface, which articulates with the carpus,
and internally a small one, which articulates with the ulna. The carpal
* When the arm is at rest it hangs naturally with the thumb directed forwards and
inwards, as in partial pronation ; but in anatomical description the forearm is placed as
in supination, with the thumb directed outwards and the palm of the hand looking
forwards.
RADIUS. ULXA.
81
articular surface, which is slightly concave, is somewhat five-sided and divided
by a line into a quadrilateral internal part, which articulates with the seini-
lunar bone, and a triangular external part, which articulates with the
scaphoid bone. The ulnar articular surface is vertical, and forms a right
Fig. 71. RIGHT RADIUS FROM BEFORE.
Fig. 72. RIGHT RADIUS FROM BEHIND.
i
Fig. 71.
Fig. 72.
1, head, showing the hollow above for the humerus,
and the short cylindrical surface surrounding it for
the ulnar articulation ; 2, the neck ; 3, the tubercle ;
4, is opposite to the oblique line ; 5, internal border
or interosseous ridge ; the shaded part near 5 marks
the slight hollow in which the flexor longus pollicis
muscle lies ; 6, carpal articular surface ; 7, styloid
process ; 8, the articular hollow for the lower end
of the ulna; 9, impression at the middle of the
outer border of the attachment of the pronator radii
teres ; 10 and 11, oblique depressions marking the
places of the extensor longus digitorum and extensor
ossis metacarpi pollicis ; between 7 and 8, the dorsal
grooves for the tendons of the extensor muscles.
10
angle with the inferior surface ; it is concave
from before backwards, forming a semilunar
cavity, in which the rounded lower end of the
ulna plays. At the external angle of the
inferior surface a part projecting downwards,
called the styloid process, gives attachment to
the external lateral ligament of the wrist
joint, while the anterior and posterior margins
are likewise rough and prominent for other liga-
ments. On its external and posterior aspects
the inferior extremity of the radius is marked
by grooves, which transmit the extensor ten-
dons. Thus, on the external border, is a
flat groove directed downwards and forwards
which lodges the extensor ossis metacarpi and 7 7
extensor primi internodii pollicis ; and on the
posterior surface are three grooves, the middle one of which, oblique and
narrow, and with prominent borders, lodges the extensor secundi internodii
pollicis ; while of the two others, which are broad and shallower, the
external, subdivided by a slight mark, gives passage to the extensores carpi-
radiales longior and brevior, and the internal transmits the extensor communis
digitorum and extensor iudicis.
THE ULNA.
The ulna is the internal of the two bones of the forearm. It is longer
than the radius by the extent of the olecranon process. It is largest at
its upper extremity, and is curved and three-sided elsewhere, except for a
short distance at the lower end, where it is straight and cylindrical. It is
inclined downwards and outwards from the humerus in such a direction
that a straight line passing from the great tuberosity of the humerus down-
wards through the capitellum would touch the lower end of the ulna.
The ulna articulates with the humerus and the radius : in the natural
skeleton it is not in contact with the carpal bones, being separated from
the cuneiform bone by an interarticular fibro- cartilage.
82
BONES OF THE UPPER LIMB.
The superior extremity of the ulna presents for articulation with the
humerus a large articular surface, the great sigmoid cavity, which looks
forwards and is bounded in its posterior and upper part by the olecranon, a
thick process continued upwards from the shaft, and in its lower part by
the coronoid process, which projects forwards. The great sigmoid cavity is
concave from above downwards, with its inferior wall deeper than its superior,
and is convex from side to side, being traversed by a vertical ridge. The
part external to this ridge is broad and convex above, while the part internal
to the ridge is broad and concave below : a slight constriction, and some-
times a notch of division, occurs across the middle of the cavity. Continuous
Fig. 73.
Fig. 73. RIGHT ULNA FROM BEFORE.
Fig. 74. RIGHT ULNA FROM BEHIND AND WITHOUT. ^
1, point or beak of the olecranon ; 2, tuberosity of
the olecranon ; 3, end of the coronoid process ; 4,
greater sigmoid articular surface, 4 points to the
upper division of this surface ; 5, lesser sigmoid
cavity, and below it the ridge for the supinator brevis
muecle ; 6, external border or interosseous ridge ; 7,
lower extremity or head ; 8, styloid process ; 9,
rough surface of insertion of the brachialis anticus
muscle on the front of the coronoid process ; below
10, the oblique line marking the attachment of the
pronator quadratus muscle; 11, triangular surface
for the anconeous muscle ; 12, tipper part of the
posterior border, to the right of which the depressions
for the long extensor muscles of the fingers occupy
the posterior surface.
with the great is the small sigmoid cavity,
a small articular surface on the outer side
of the base of the coronoid process, slightly
concave from before backwards, and articula-
ting with the cylindrical part of the head of
the radius. The olecranon forms by its
anterior surface a part of the articular sur-
face of the great sigmoid cavity ; superiorly,
broad and uneven, it gives attachment to
the triceps extensor muscle, and posteriorly ifc
presents a subcutaneous surface which is
continuous with the posterior margin of the
shaft. Between its anterior and superior
surfaces is an acute projection which fits, in
extension of the elbow, into the olecranon fossa
of the humerus, and between the superior and
posterior surface is a rectangular prominence
which forms the point of the elbow. The coronoid process terminates in a
sharp ridge, the prominent anterior extremity of which is received during
flexion into the coronoid fossa of the humerus : its superior surface forms
part of the surface of the great sigmoid cavity ; the inferior surface rises
gradually from the anterior surface of the bone, and is covered by a large
triangular roughness which gives iDsertion to the brachialis anticus muscle.
The body or shaft in the upper three-fourths of its extent is three-sided,
and presents a slight curve with the convexity backwards, but near the
lower extremity is slender, straight and cylindrical. The anterior surface
is grooved in the upper half, where the flexor profundus muscle takes origin ;
and at its lower end has an oblique line to which the pronator quadratus
T'LXA. CARPUS.
83
is attached. Placed near the upper third is a foramen for vessels, directed
upwards into the medullary cavity. The internal surface is smooth,
and somewhat excavated superiorly on the side of the olecranon, where
it gives attachment to the flexor profundus muscle, while inferiorly it is sub-
cutaneous. The posterior surface, more uneven, looks outwards and back-
wards ; an oblique ridge, descending from behind the small sigmoid cavity,
limits a superior triangular area, which extends over the outer side of the
olecranon and gives attachment to the anconeous muscle ; immediately below
the small sigmoid cavity is a short space looking directly outwards, to which
the supinator brevis is attached ; while the remaining and largest part of this
surface is slightly impressed by the extensor muscles. Of the three margins,
the anterior and posterior are rounded, and for the most part smooth ; the
external is sharp, and gives attachment to the interosseous ligament.
The inferior extremity presents a rounded articular head ; and on the
internal aspect of the head a short cylindrical projection, the styloid process,
which descends in a line with the inner and posterior surface of the shaft,
and gives attachment to the internal lateral ligament of the wrist joint. The
head presents two aspects, of which one, flattened and circular in form, looks
towards the wrist joint ; whilst the other, narrow and cylindrical, looks out-
wards, and is received into the semilunar cavity in the contiguous border of
the radius. The head and the styloid process are separated posteriorly by
a groove, which is traversed by the tendon of the extensor carpi ulnaris ;
and inferiorly by a depression, into which the triangular fibro-cartilage
which intervenes between the ulna and the carpus is inserted.
THE CARPUS.
The carpus is composed of eight short bones, which are disposed in two
ranges, four in each range. Enumerated from the radial to the ulnar side,
the bones which constitute the first or superior range are named scaphoid,
semilunar, cuneiform, and pisiform ; those of the second or inferior range.
trapezium, trapezoid, os magnum, and unciform.
Fig. 75. HALF-DIAGRAMMATIC VIEW OP
THE CARPUS AND PROXIMAL PARTS OF THE
METACARPAL BONES, FROM BEFORE, WITH
THE CARPAL BONES SLIGHTLY SEPARATED
TO SHOW THE FORM OF THEIR SURFACES
OF CONTACT WITH EACH OTHER. f
p-
1, scaphoid bone ; 2, semilunar, pre-
senting in this instance, as often occurs, a
small surface of articulation with the unci-
form bone ; 3, cuneiform or pyramidal ;
4, pisiform, laid upon the last ; 5, trape-
zium, the figure is placed upon the ridge,
to the inside of which is the groove for the
tendon of flexor carpi radialis ; 6, trapezoid
bone ; 7, os magnum, the figure is placed
on the tuberosity ; 8, unciform bone, the
figure is placed on the unciform process. The metacarpal bones will be distinguished by
the first being articulated separately with the trapezium. The articulation of the os
magnum with the fourth metacarpal bone is represented somewhat too large.
The dorsal surface of the carpus is convex, the palmar is concave from
side to side, the concavity being bounded by four prominences, one at the
outer and one at the inner extremity of each range. The anterior annular
G 2
84 BONES OF THE UPPER LIMB.
ligament is stretched across the carpus between these prominences, so as to
form a canal for the transmission of the flexor tendons.
The superior surfaces of the scaphoid, semilunar and cuneiform bones
form, when in apposition, a continuous convexity which corresponds with
the concavity presented by the radius and the interarticular cartilage, while
the pisiform bone is attached in front of the cuneiform, with which alone it
articulates. The line of articulation between the superior and inferior ranges
is concavo-convex from side to side, the trapezium, trapezoid and os magnum
bounding a cavity which lodges the external part of the scaphoid, and the
os magnum and unciform rising up in a convexity, which is received into a
hollow formed by the scaphoid, semilunar, and cuneiform bones.
THE SCAPHOID BONE.
The scaphoid, or navicular bone, the largest and most external of the
first row of carpal bones, is of a curved form, and lies with its longest axis
directed outwards and downwards. Its superior surface, convex and smooth
for articulation with the radius, is inclined backwards, so that the posterior
surface of the bone is not so deep as the anterior. The internal surface,
narrow from above downwards, articulates with the semilunar bone. The
outer extremity, rough superiorly for the attachment of ligaments, presents
inferiorly an articular convexity, which occupies the hollow formed by the
upper surfaces of the trapezium and trapezoid bones, and is continuous
with a large concave surface extending over the rest of the inferior aspect
of the bone, and articulating with the os magnum. The fore part of the
outer extremity of the scaphoid bone projects forwards, forming one of the
tubercles to which the anterior annular ligament is attached. The scaphoid
articulates with five bones, viz., the radius, the semilunar, trapezium,
trapezoid, and os magnum,
THE SEMILTJNAR BONE.
The semilunar, or lunate bone, irregularly cubic, is named from the
crescentic concavity from before backwards of its inferior surface, which
rests on the head of the os magnum, and frequently also by a bevelled edge
slightly on the uuciform bone. Its external surface is vertical, and articu-
lates with the scaphoid bone ; its internal surface looks downwards and
inwards, is much deeper and narrower than the external, and articulates
with the cuneiform. The convex superior surface, which articulates with
the radius, is inclined, like that of the scaphoid, more backwards than
forwards, and hence the anterior surface is deeper than the posterior. The
semiluuar articulates with five bones, viz., the radius, scaphoid, cuneiform,
os magnum, and unciform.
THE CUNEIFORM BONE.
The cuneiform, or pyramidal bone, is somewhat wedge-shaped, its internal
extremity, rough for ligaments, forming the blunt narrow end of the wedge.
Superiorly it presents an articular surface, which glides upon the triangular
cartilage interposed between it and the ulna ; externally it articulates with
the semilunar bone, and inferiorly with the unciform, by means of a surface
which is concavo-convex from without inwards. Its anterior surface is dis-
tinguished from the posterior by a smooth circular facet on its outer half,
which articulates with the pisiform bone. The cuneiform articulates with
three bones, viz., the semilunar, pisiform, and unciform.
CARPAL BONES. 85
THE PISIFORM BONE.
The pisiform bone, or os rotundum, so called from its resemblance to a
pea, lies on a plain anterior to the other bones of the carpus. Posteriorly
it possesses an articular surface, which rests on the cuneiform bone. The
mass of the bone is so inclined from this surface downwards and outwards,
that the pisiform bone of one hand is distinguishable from that of the other.
Fig. 76. DORSAL VIEW OP THE CARPUS, WITH A
PORTION OF EACH OF THE METACARPAL BONES. ^ Fig. 76.
1, scaphoid; 2, serailunar; 3, cuneiform; 4,
pisiform; 5, trapezium; 7, trapezoid ; 8, os mag-
num ; 9, unciform.
THE TRAPEZIUM.
The trapezium, or os multangulum majus,
is the most external of the second row of
carpal bones. It presents a rhombic form
when seen from its dorsal or palmar aspect,
and has its most prominent angle directed
downwards. Its anterior surface is marked
by a vertical groove traversed by the tendon
of the flexor carpi radialis muscle, and external to the groove by a ridge,
or tubercle, one of the four prominences which give attachment to the
anterior annular ligament. Of the internal sides of the rhomb, the
superior articulates with the scaphoid bone, the inferior with the trapezoid
bone, and by a small facet close to the inferior angle also with the second
metacarpal bone. Of the external sides the superior is rough, and the
inferior presents a smooth surface convex from behind forwards, and concave
from without inwards, which articulates with the metacarpal bone of the
thumb, and is separated by a rough line at the inferior angle from the surface
for the second metacarpal bone. The trapezium articulates with four bones,
viz., the scaphoid, trapezoid, and first and second metacarpals.
THE TRAPEZOID BONE.
The trapezoid bone, or os multangulum minus, is considerably smaller
than the trapezium. Its longest diameter is from before backwards. Its
posterior surface, which is pentagonal, is much larger than the anterior.
The external inferior angle of the anterior surface is distinguished by being
prolonged a little backwards between the trapezium and second metacarpal
bone. The superior surface articulates with the scaphoid bone ; the
external with the trapezium ; the internal with the os magnum ; and the
inferior by a large surface convex from side to side with the second meta-
ca.rpal bone. The trapezoid articulates with four bones, viz., the scaphoid,
trapezium, os magnum, and second metacarpal bone.
THE OS MAGNUM.
The os magnum, or os capitatum, is the largest of the carpal bones. In
form it is elongated vertically, rectangular inferiorly, rounded superiorly.
The articular surface of the superior extremity or head is prolonged on the
outer, but not on the inner side, and is continued further down behind
than in front. A neck is formed beneath by depressions on the anterior
and posterior surfaces. The anterior surface of the bone is much narrower
than the posterior. The posterior surface projects downwards at its
86
BONES OF THE UPPER LIMB.
internal inferior angle. On the external side beneath the surface for the
scaphoid is a short surface for the trapezoid bone ; and on the internal
surface is a vertically elongated surface which articulates with the uncifonn
bone. Inferiorly this bone articulates by three distinct surfaces, of which
the middle is much the largest, with the second, third, and fourth metacarpal
bones. The os magnum articulates with seven bones, viz., the scaphoid,
semilunar, trapezoid, unciform, and second, third, and fourth metacarpal bones.
THE UNOIFORM BONE.
The unciform bone is readily distinguished by the large process projecting
forwards and curved slightly outwards on its anterior surface. Seen from
the front or behind, it has a triangular form. Its external surface is ver-
tical, and articulates with the os magnum ; its inferior surface is divided
into two facets which articulate with the fourth and fifth metacarpal bones ;
its superior surface, meeting the cuneiform, is concavo-convex, inclines
upwards and outwards towards the head of the os magnum, and is separated
internally by a rough border from the inferior surface. The unciform
articulates with five bones, viz., the os magnum, semilunar, cuneiform, and
fourth and fifth metacarpal bones.
THE METACARPUS.
The metacarpus, the part of the hand which supports the fingers, consists
of five shafted bones, which are numbered from without inwards. These
bones are placed in a slightly arched plane, and are nearly parallel one with
the other, with the exception of the first, which diverges from the second.
Fig. 77.
Fig. 77. THE RIGHT HAND FROM BEFORE.
5, scaphoid bone ; I, semilunar ; c, cuneiform ;
p, pisiform ; t, trapezium ; next it the trape-
zoid, not lettered ; next the os magnum, also not
lettered ; u, unciform.
I to V, the metacarpal bones j 1, 3, first and
second phalanges of the thumb; 1, 2, 3, the
first, second, and third phalanges of the little
finger, and similarly for the other three fingers,
not marked ; *, one of the sesamoid bones of the
thumb seen sidewise.
The metacarpal bones are slightly
curved, so as to present a concavity
directed forwards. They are terminated
at their carpal extremities by expanded
portions of different forms, and at the
digital ends by large rounded heads.
The first metacarpal bone is thicker and
shorter than the others. Of the remain-
ing bones the third is the longest and
thickest, and the second, fourth, and fifth
decrease regularly in length, according to
their position from without inwards.
The shaft of the first metacarpal bone is somewhat compressed from
before backwards, flat behind, and transversely convex in front. The
shafts of the others are prismatic, presenting a broad surface towards
the back of the hand, and towards the palm a rounded margin between
the two lateral surfaces. They are most slender immediately beyond the
carpal extremity, and become gradually thicker towards the head. They
METACABPAL BONES AND PHALANGES.
87
present on their dorsal surfaces each a triangular subcutaneous area, bounded
by lines which, proceeding from the sides of the head, pass upwards and con-
verge in the second, third, and fourth metacarpal bones opposite the middle
of the carpal extremity, aud in the fifth towards its inner side.
The heads or digital extremities articulate with the proximal phalanges.
Their smooth rounded surfaces are broader, and extend further on the
palmar than on the dorsal aspect of the bones; and on the sides present
hollows and elevations for the attachment of ligaments.
The carpal extremity presents distinctive peculiarities in each metacarpal
bone. That of the first has only one articular surface, concave from
before backwards, and convex from side to side, which articulates with the
trapezium; and posteriorly a rough prominence, to which the extensor
metacarpi pollicis is attached. The second presents a transversely concave
surface which receives the trapezoid bone ; on the radial side it articulates
by a small facet on its posterior part with the trapezium, on the ulnar side
with the third metacarpal bone, and by a narrow facet wedged between the
third metacarpal and trapezoid bones, with the os magnum. The third
bone articulates superiorly with the os magnum, and on the sides with the
contiguous metacarpal bones : at its posterior and outer angle it forms a
projection upwards. The fourth articulates principally with the unciform
bone above, but also by a narrow facet with the os magnum ; on its radial
side are two small surfaces, and on the ulnar side one, for articulation with
the adjacent metacarpal bones. The fifth articulates superiorly with the
unciform bone by means of a concave surface inclined slightly outwards, and
externally with the fourth metacarpal bone, while on its ulnar side it
presents a rough and prominent tuberosity.
From the proximal position of its epiphysis, the metacarpal bone of the thumb
has been considered by Winslow and some other anatomists, as a phalanx of the first
row, and the bone which it supports a phalanx of the middle row.
THE DIGITAL PHALANGES.
Fig. 78. RIGHT HAND SEEN FROM BEHIND. |
The indications are the same as in the pre-
ceding figure.
The digital phalanges, or inter nodia,
are fourteen in number; three for each
finger, except the thumb, which has
only two. In each instance the first or
proximal phalanx is longer than the
second, and the second longer than the
third.
Those of the first row are slightly
curved like the metacarpal bones.
Their dorsal surfaces are smooth and
transversely convex; the palmar are
flat from side to side, and bounded by
rough margins, which give insertion to
the fibrous sheaths of the flexor ten-
dons. Their proximal extremities are
thick, and articulate each by a trans-
versely oval concave surface with the
corresponding metacarpal bone. Their distal extremities, smaller and more
88
BONES OF THE UPPER LIMB.
compressed antero-posteriorly, are each divided by a shallow groove into two
condyles.
Those of the middle row are four in number. Smaller than those of the
preceding set, they resemble them in form, with this difference, that their
proximal extremities present on the articular surface a slight middle elevation
and two lateral depressions, adapted to articulate with the condyles of the
first phalanges.
The terminal or ungual phalanges, five in number, have proximal extremi-
ties similar to those of the middle row, but with a rough depression in front,
where the flexor tendons are inserted. They taper towards their somewhat
flattened and expanded free extremities, which are rough and raised round
the margins and upon the palmar aspect in the ungual process.
SESAMOID BONES. A pair of sesamoid bones is placed in the palmar wall
of the metacarpo-phalangeal articulation of the thumb; and similar nodules,
single or double, are sometimes found in the corresponding joint of one or
more of the other fingers, most frequently of the index and little fingers.
DEVELOPMENT OF THE UPPER LIMB.
FIRST APPEARANCE OF THE LIMBS. The earliest traces of limbs in the human
embryo are observed in the fourth or fifth week as elevations of the ventral plates
on the sides of the body, tipped with a thickening of the cuticle. In the fifth
or sixth week there is distinguishable in each a laterally compressed expansion, the
rudimentary hand or foot, and a more cylindrical pedicle, the arm or leg. About
the eighth week the division into fingers and toes takes place, the pollex of each
1 year. 15 or 16 years. 17 or 18 years.
22 years.
Fig. 79. OSSIFICATION OP THE SCAPULA.
A, the scapula from a child of about one year old. 1, shows the large spreading ossifi-
cation from the primary centre. 2, the commencing nucleus in the coracoid process.
B, the scapula from a boy of about fifteen or sixteen years. The coracoid process,
(represented as too much separate in the figure), is now partially united at its base ; a
nucleus, 3, has appeared in the acromion, and another, 4, at the lower angle.
C, shows the condition of the scapula at seventeen or eighteen years of age ; a second
point, 5, has appeared in the acromion, and ossification has advanced into the ridge of
the base, 6.
D, the scapula of a man of about twenty-two years of age ; the acromion and the ridge
of the base are still separate. A thin scale on the coracoid process and an epiphysis of
the glenoid head, which sometimes occur, have been omitted.
OSSIFICATION OF SCAPULA AND CLAVICLE.
89
limb being developed on the superior margin. The upper limb appears before the
lower, and sooner exhibits a separation of digits. The division into arm and forearm,
thigh and leg, is observable about the eighth week (Kolliker, loc. cit.). The nerves
are seen extending directly into the limbs soon after their first appearance ; but it is
not determined whether the bones and muscles are derived from extensions of the
dorsal plates, or have an independent origin in the ventral plates.
OSSIFICATION OP THE UPPER LIMB. With the exception of the clavicle, all the bones
of the upper limb begin to ossify from cartilage. The Scapula is developed in the
greater part of its extent from a single osseous nucleus, but possesses also supplementary
nuclei in the coracoid process and acromion, and along the base. The nucleus of the
coracoid process is especially worthy of attention, both because it appears in the first
year, while the other supplementary nuclei are formed only after puberty, and because,
although reduced to a mere epiphysis in mammals, it forms a distinct and sometimes
large bone in other vertebrate animals. The acromion is ossified from two or more
nuclei. Along the base of the young scapula a strip of cartilage extends, corre-
sponding with a much more largely developed permanent cartilage found in many
animals ; and in this there first appears a nucleus of bone at the inferior angle, then
a prolonged ossification throughout its length. Occasionally a separate epiphysial
lamina occurs, in the border of the glenoid cavity.
Fig. 80. OSSIFICATION OF THE CLAVICLE. Fig. 80.
a, the clavicle of a foetus at birth, osseous in
the shaft, 1, and cartilaginous at both ends.
b, clavicle of a man of about twenty-three
years of age ; the shaft, 1, fully ossified to tbe
acromial end ; the sternal epiphysis, 2, is repre-
sented rather thicker than natural.
The Clavicle begins to ossify before any other bone in the body. Its ossification
commences before the deposition of cartilage in connection with it, but afterwards
progresses in cartilage as well as in fibrous substance. It is formed from one prin-
cipal piece, and has a thin epiphysis at its sternal end.
Fig. 81. OSSIFICATION OF THE HUMERTTS.
A, humerus of a full-grown foetus; B, humerus at two years of age ; C, in the third
year ; D, at the beginning of the fifth year ; E, at about the twelfth year ; F, at the age
of puberty.
1, the primary piece for the shaft ; 2; nucleus for the articular head ; 3, that for the
tuberosity ; 4, for the radial condyle and adjacent part of the trochlea ; 5, for the inner
er trochlear eminence ; 6, for the inner part of the trochlea ; 7, for the external or
eapitellar eminence.
90 BONES OF THE UPPER LIMB.
The Humerus is formed, like most of the long bones, from a principal centre for the
shaft, and from a superior and an inferior terminal epiphysis. The superior epiphysis
is formed by the union of two original nuclei one in the head, the other in the great
tuberosity, to which is added, according to Beclard and Humphry, a nucleus
belonging to the small tuberosity. The inferior epiphysis has four original nuclei,
the largest of which extends inwards from the capitellum, while a small one
appears at the inner part of the trochlea, and one in each supracondyloid eminence ;
the internal supracondyloid epiphysis remains distinct from the other three nuclei,
which become fused into one mass previous to their union with the shaft.
The Radius and Ulna are each developed from an osseous centre in the middle of
the shaft and from an epiphysial nucleus in each extremity. The epiphyses of the
ulna are very small ; the upper one involves only the extremity of the olecranon.
The Carpus is entirely cartilaginous at birth. Each Carpal bone is ossified from a
single nucleus.
The Metacarpal bones and Phalanges are formed each from a principal piece and
one epiphysis. The ossification of the principal pieces begins at an early period.
In the four inner metacarpal bones the epiphysis is at the distal extremity, while
in the metacarpal bone of the thumb and in the phalanges it is placed at the
proximal extremity.
PERIODS OF OSSIFICATION OF THE BONES OF THE UPPER LIMB.
I. Scapula.
The principal nucleus appears in the 7th or 8th week.
The nucleus of the coracoid process appears in the 1st or 2nd year.
The two nuclei of the acromion appear from the 14th to the 16th year.
The nuclei of the inferior angle, base, and glenoid cavity, appear from the 16th
to the 18th year.
The coracoid process and body unite about the time of puberty.
The other parts unite from the 22nd to the 25th year.
II. Clavicle.
The principal nucleus (earliest of all bones) appears about the 6th week.
The epiphysis of the sternal end appears from the 18th to the 20th year.
The epiphysis and shaft unite about the 25th year.
III. Humerus.
The nucleus of the shaft appears in the 7th week.
The nucleus of the head appears in the 2nd year.
The nucleus of the great tuberosity appears in the 3rd year.
The nucleus of the small tuberosity (when separate) appears in the 5th year.
The nucleus of the capitellum appears in the 3rd year.
The nucleus of the internal supracondyloid eminence appears in the 5th year.
The nucleus of the trochlea appears in the llth or 12th year.
The nucleus of the external supracondyloid eminence appears in the 13th or
14th year.
The nucleus of the tuberosity and head unite in the 5th year.
The capitellar, trochlear, and external supracondyloid nuclei unite with the shaft
in the 16th or 1 7th year.
The internal supracondyloid nucleus unites with the shaft in the 18th year.
The superior epiphysis and shaft unite in the 20th year.
IV. Radius.
The nucleus of the shaft appears in the 7th or 8th week.
The nucleus of the carpal extremity appears at the end of the 2nd year.
The nucleus of the head appears in the 5th year.
The superior epiphysis and shaft unite about the 17th or 18th year.
The inferior epiphysis and shaft unite about -the 20th year.
V. Ulna.
The nucleus of the shaft appears in the 8th week.
OSSIFICATION OF THE ARM AJS T D FOREARM.
Fig. 82.
91
Fig. 82. OSSIFICATION OP THE RADIUS.
A, the radius of a full-grown foetus ; B, the radius at about two years of age ; C, at
five years ; D, at about eighteen years.
1, the primary piece or shaft ; 2, the ossific point of the lower or carpal epiphysis ;
3, that of the upper end. In D, the upper epiphysis is already united to the shaft,
while the lower epiphysis is still separate.
Fig. 83.
Fig. 83. OSSIFICATION OF THE ULNA.
A, the ulna of a child at birth ; B, the ulna of a child at the end of the fourth year ;
C, of a boy of about twelve years of age; D, the ulna of a male of about nineteen or
twenty years.
1, the primary piece of the shaft ; 2, the nucleus of the lower epiphysis ; 3, the
nucleus of the upper epiphysis. In D, the upper epiphysis is united to the shaft, while
the lower one is still separate.
92
BONES OF THE UPPER LIMB.
Fig. 84.
Fig. 84. OSSIFICATION OF THE BONES OF THE HAND.
A, represents the state of the bones and cartilages at the period of birth. The carpus
is entirely cartilaginous. Each of the metacarpal bones and digital phalanges has its
primary centre of ossification.
B, the state of the bones in a child at the end of the first year; the os magnum and
unciform bone have begun to ossify.
C, the condition about the third year. Additional centres of ossification are seen in
the cuneiform and in the proximal epiphysis of the first and the distal epiphyses of the
other four metacarpal bones, and in the proximal epiphyses of the first row of phalanges.
D, the condition at the fifth year. Additional centres have been formed, first in the
trapezium, and later in the semilunar bone, and in the middle and distal phalanges :
(the figure does not show them distinctly in the middle phalanges).
E, the condition at about the ninth year. Additional centres have been formed in the
scaphoid and trapezoid bones, and the more developed epiphyses of the metacarpal bones
and phalanges are shown, in the first and second separately.
1, os magnum ; 2, unciform ; 3, cuneiform ; 4, semilunar; 5, trapezium ; 6, scaphoid ;
7, trapezoid ; 8, metacarpal bones, the principal piece ; 8% four metacarpal epiphyses ;
8', that of the thumb ; 9, the first range of phalanges ; 9*, their epiphyses ; 9', that of
the thumb; 10, second range of phalanges ; 10', epiphysis of terminal phalanx of thumb;
11, terminal range of phalanges of the fingers; 11*, their epiphyses.
THE PELVIS AXD LOWER LIMB. 93
Ulna continued.
The epiphysis of the carpal extremity appears in the 4th or 5th year.
The epiphysis of the olecranon appears in the 10th year.
The superior epiphysis and shaft unite about the 17th year.
The inferior epiphysis and shaft unite about the 20th year.
VI. Carpus.
The nucleus of the os magnum appears in the 1st year.
The nucleus of the unciform bone appears in the 1st or 2nd year.
The nucleus of the cuneiform bone appears in the 3rd year.
The nuclei of the trapezium and semilunar bones appear in the 5th year.
The nucleus of the scaphoid bone appears in the 6th or 7th year.
The nucleus of the trapezoid bone appears in the 7th or 8th year.
The nucleus of the pisiform bone appears in the 12th year.
VII. Metacarpus.
The nuclei of the shafts appear in the 8th and 9th week.
The nuclei of the epiphyses appear from the 3rd to the 5th year.
The epiphyses and shafts unite about the 20th year.
VIII. Phalanges.
The nuclei of the shafts appear in the 8th, 9th, and 10th weeks.
The nuclei of the epiphyses appear from the 3rd or 4th to the 5th or 6th years.
The epiphyses and shafts unite before the 20th year.
NOTE. From what is stated above it appears that in the bones of the arm and
forearm the epiphyses which meet at the elbow-joint begin to ossify later and unite
with their shafts earlier than those at the opposite ends of the bones, while in the
bones of the thigh and leg the epiphyses distant from the knee-joint are the latest
to ossify (excepting the fibula) and the first to unite with their shafts. In the bones
of the arm and forearm the nutrient foramina are directed towards the elbow ; in
those of the thigh and leg they are directed away from the knee. Thus in each
bone the epiphysis of the extremity towards which the nutrient foramen is directed
is the first to be united to the shaft.
V. THE PELVIS AND LOWER LIMB.
The divisions of the lower limb are the haunch or hip, thigh, leg, and foot.
In the haunch is the innominate bone, which, as entering into the formation
of the pelvis, likewise constitutes part of the skeleton of the trunk ; in the
thigh is the femur ; in the leg the tibia and fibula ; and at the knee
a large sesamoid bone, the patella. The foot is composed of three parts ;
the tarsus, metatarsus, and phalanges.
THE INNOMINATE BONE.
The innominate bone, os coxce, or pelvic bone, with its neighbour of the
opposite side and the addition of the sacrum and coccyx, forms the pelvis ;
it transmits the weight of the body to the lower limb. In form it is con-
stricted in the middle and expanded above and below, and is so curved
upon itself that while tha superior expansion is directed inwards posteriorly
and outwards anteriorly, the inferior part is curved inwards so as to reach
the middle line in front. On the external aspect of the constricted portion
is the acetabulum, a cavity which articulates with the femur, and per-
forating the inferior expansion is a large opening, the obturator foramen.
The superior wider part of the bone forms part of the abdominal wall : the
inferior enters into the formation of the true pelvis. The innominate bone
articulates with its fellow of the opposite side, with the sacrum and with the
femur.
In the description of this bone it is convenient to recognise as distinct
the three parts of it which are separate in early life, viz., the ilium, os
94
BONES OF THE LOWER LIMB.
pubis, and ischium. These three portions meet at the acetabulum, in the
formation of which they all take part ; and the os pubis and ischium also
meet on the inner side of the obturator foramen.
Fig. 85. RIGHT Os INNOMTNATUM
FROM THE DORSAL ASPECT. ^
1, anterior superior spinous pro-
cess ; 2, anterior inferior ditto ; 3,
posterior superior ; 4, posterior in
ferior spinous process ; 5, crest of
the ilium ; 6, surface occupied by
the gluteus medius muscle above
the superior curved line ; above 3,
is a rough surface to which the
gluteus maximus is attached ; 7,
surface between the superior and
inferior curved lines occupied by
the gluteus minimus ; 8, groove
above the acetabulum, occupied by
the posterior tendon of the rectus
femoris ; 9, superior ramus of tho
pubis and pectineal eminence ; 1 0,
crest and spinous process of the
pubis; 11, place of meeting of the
descending or inferior ramus of the
pubis with the ascending ramus of
the ischium ; 12, spine, and 13,
tuberosity of the ischium ; 14, car-
tilaginous surface of the acetabu-
lum ; and 15, synovial depression
and pit for the round ligament ;
16, thyroid or obturator foramen ;
17, greater, and 18, lesser sciatic
notches ; between the acetabulum
and the ischial tuberosity is seen
the groove occupied by the obtu-
rator externus muscle.
10
U
The ilium constitutes the superior expanded portion of the bone, and
forms a part of the wall of the acetabulum by its inferior extremity. Above
the acetabulum it is limited anteriorly and posteriorly by margins which
diverge at right angles one from the other, and superiorly by an arched
thick and extensive border, the crista ilii. The crest is curved like the letter
f, the anterior extremity pointing slightly inwards and the posterior out-
wards ; its surface is broadest in its anterior and posterior thirds, it is rough
for the attachment of muscles, and on it may be distinguished an external
and internal lip and an intermediate space. The anterior extremity of the
crest forms a projection forwards called the anterior superior spine of the
ilium, and, separated from it by a concave border, and placed immediately
above the acetabulum, is another eminence called the anterior inferior spine :
the projecting posterior extremity of the crest forms the posterior superior
spine, and separated from it by a notch is the posterior inferior spine, below
which the posterior border of the bone is hollowed out into the great sciatic
notch. The external surface, or dorsum of the ilium, concavo-convex from
behind forwards, presents, close to the posterior extremity of the crest, a
roughness of some extent, to which the gluteus maximus muscle is attached,
and is traversed by two rough arched lines, one of which, the superior curved
line, beginning in front at the upper border of the bone, about an inch and
a half from its anterior extremity, arches backwards to the upper part of
the great sciatic notch, while the other, the inferior curved line, shorter
INNOMINATE BONE.
95
and less strongly marked, extends from the space between the anterior
spinous processes to the middle of the great sciatic notch. The space be-
tween the crest and the superior curved line has the form of a curved triangle,
broad behind and pointed in front, and gives attachment to the gluteus
medius muscle, while that between the two curved lines gives attachment
to the gluteus minimus. The internal surface of the ilium is divided into
three parts. The anterior of these, the largest, is called the iliac fossa; it
is concave and smooth, and towards the middle of it the bone is very thin.
The posterior part is subdivided ; presenting inferiorly for cartilaginous
articulation with the sacrum the smooth but uneven auricular surface, broad
in front and extending to the posterior inferior spine behind ; and superiorly
a more uneven and rough surface for the attachment of ligaments. The
third part, entering into the formation of the true pelvis, is not dis-
tinguished by any mark in the adult from the ischium and os pubis ;
it is separated from the iliac fossa by a smooth border, the iliac portion of
the ilio-pectineal line, which extends from the auricular surface to the pubic
spine.
Fig. 86. EIGHT Os INNOMINATUJI,
FROM THE INNER OR PELVIC
SURFACE. i
2, 3, 4, 5, 13, 16, 17, and 18,
indicate the same parts as in the
preceding figure ; 19, iliac fossa ;
20, ilio-pectineal line or brim of
the true pelvis, ending at 24 ; 21,
auricular cartilaginous sacro-iliac
surface ; 22, rough tuberculated
surface for the posterior sacro-iliac
ligaments ; 23, oval surface of the
symphysis pubis ; 24, spinous pro-
cess of the os pubis, terminating the
crest of the pubis and the ilio-
pectineal line ; between 17 and
20, the pelvic surface of the ilium.
The os pubis or os pectinis
forms the anterior wall of the
pelvis, and bounds the obtu-
rator foramen in the upper
half of its extent. At its
outer and upper extremity it
forms a part of the aceta-
bulum ; at its inner extremity
it presents an elongated oval surface, articulating by fibro-cartilage
with the bone of the opposite side, its junction with which is called the
symphysis pubis. The part which passes downwards and outwards below
the symphysis is called the inferior or descending ramus, the upper part is
called the superior (or horizontal) ramus, and the flat portion between the
rami may be distinguished as the body. The deep or pelvic surface of the
os pubis is smooth ; the outer surface is roughened near the symphysis by
the attachments of muscles. At the superior extremity of the symphysis
is the angle of the pubis, and extending outwards, from this on the superior
border is the rough crest, terminating in the projecting spine. The descend-
ing ramus is flat from before backwards ; the superior or ascending ramus
becomes prismatic, and increases in thickness as it passes upwards and out-
13
96 BONES OF THE LOWER LIMB.
wards, and between its posterior and superior surfaces there is prolonged
outwards from the spine a ridge called the peclineal line, which is the pubic
portion of the ilio-pectineal line. The surface in front of the pectineal
line is covered by the pectineus muscle ; the inferior surface of the superior
ramus presents a deep groove for the obturator vessels and nerve, directed
from behind forwards and inwards. Above the acetabulum the concavity
of the border extending from the anterior inferior spine of the ilium to the
spine of the pubis is interrupted by a slight elevation, the ilio-pectineal
eminence, situated at the junction of the os pubis and ilium.
The ischium is the posterior and lowest part of the os innominatum, and
bounds the obturator foramen in the lower half of its extent. Superiorly it
forms about two-fifths of the acetabulum, inferiorly it is enlarged in a thick
projection, the tuberosity, and this part, diminishing in size, is continued
forwards into the ramus. On its posterior border, behind the acetabulum,
a sharp process, the spine, projecting with an inclination inwards, forms the
inferior limit of the great sciatic notch, and is separated from the tuberosity
by a short interval, the small sciatic notch, against the smooth margin of
which glides the tendon of the obturator internus muscle. In front of
this, on the external surface, a horizontal groove, occupied by the tendon
of the obturator externus muscle, lies between the inferior margin of the
acetabulum and the tuberosity. The tuberosifcy, which is the part on which
the body rests in the sitting posture, presents a rough surface con-
tinuous with the internal margin of the ramus, and on which may be
distinguished four impressions, viz., on its upper and broad part two slight
hollows, which are placed side by side, the external corresponding to the
attachment of the semimembranosus muscle, and the internal to the con-
joined origin of the biceps and semitendiiiosus ; and inferiorly two elongated
rough elevations, likewise side by side, the external giving attachment to
the adductor magnus muscle, and the internal to the great sacro-sciatic
ligament : there is likewise along the outer margin a rough elevated line,
marking the place of origin of the quadratus femoris muscle. The ramus of
the ischium is flattened like the descending ramus of the pubis, with which
it is continuous on the inner side of the obturator foramen.
The acetabulum is a cotyloid or cup-shaped cavity, looking outwards,
downwards and forwards, and surrounded in the greater part of its
circumference by an elevated margin, which is most prominent at the
posterior and upper part; while at the opposite side, close to the
obturator foramen, it is deficient, leaving the notch or incisura. Its lateral
and upper parts present a broad bent riband-like smooth surface, which
articulates with the head of the femur, and in the recent state is coated
with cartilage, but the lower part of the cup and the region of the notch are
depressed below the level of the articular surface, lodge a mass of fat, and
have no cartilaginous coating. Rather more than two-fifths of the aceta-
bulum are formed from the ischium, less than two-fifths from the ilium, and
the remainder from the os pubis. The iliac portion of the articular surface
is the largest, the pubic the smallest : the non-articular surface belongs
chiefly to the ischium.
The obturator or thyroid foramen, also called foramen ovale, is internal
and inferior to the acetabulum. In the male it is nearly oval, with the
long diameter directed downwards and outwards ; in the female it is more
triangular, or narrowed at its lower part. In the recent state it is closed
by a fibrous membrane, except in the neighbourhood of the groove in its
upper margin.
FORM OF THE PELVIS.
97
THE PELVIS.
The ossa innominata with the sacrum and coccyx form the osseous walls
of the pelvis.
This part of the skeleton may be considered as divided into two parts at
the level of the upper border of the symphysis pubis, the sacral promontory
and the ilio-pectineal lines. The circle thus completed constitutes the brim
or inlet of the lower or true pelvis; the space above it, between the iliac
fossae, belongs really to the abdomen, but has been called the upper or false
pelvis. The inferior circumference, or outlet of the pelvis, presents three
bony eminences, the coccyx and the tuberosities of the ischium. Between
the tuberosities of the ischium in front is the pubic or subpubic arch, which
bounds an angular space extending forwards to the symphysis, and is formed
by the descending rami of the ossa pubis and the ascending rami of the
ischia. The interval between the sacrum and coccyx and the ischium on
each side is bridged over in the recent state by the sacro-sciatic ligaments,
which therefore assist in bounding the outlet of the pelvis.
Fig. 87.
Fig. 87.
VIEW OP THE PELVIS
OP A MIDDLE-AGED
MAN, AS SEEN FROM
BEFORE, IN THE
ERECT ATTITUDE OF
THE BODY. ^
1, 2, anterior ex-
tremities of the
crest of the ilium in
front of the widest
transverse diameter
of the upper or false
pelvis ; 3, 4, aceta-
bula; 5, 5, thyroid
or obturator fora-
mina ; 6, subpubic
angle or arch.
Fig. 88.
VIEW OF THE PELVIS
OF A MIDDLE-AGED
WOMAN. J
Similarly placed with
that shown in the
preceding figure, and
designed to illustrate,
by comparison with
it, the principal dif-
ferences between the
male and female pel-
vis, viz. , the greater
distance in the female
between the aceta-
bula, the wider and
shallower true pelvis,
the triangular form
of the obturator fo-
ramen, the greater
width between the tuberosities of the ischium, and the greater width of the sub-pubic
arch. The numbers indicate the same parts as in the preceding figure.
Fig. 88.
BOXES OF THE LOWER LIMB.
Position of the Pelvis. In the erect attitude of the body, the pelvis is
so inclined that the plane of the brim of the true pelvis forms an angle
with the horizontal, varying in different individuals from 60 to 65. The
base of the sacrum was found by Nagele in a large number of well-formed
female bodies to be about 3j inches above the upper margin of the sym-
physis pubis; the level of the top of the coccyx he found varying from
22 lines above the apex of the pubic arch to 9 lines below the same point,
and on an average to be V or 8 lines above it (Nagele, "Das weibliche
Becken," &c., Carlsruhe, 1825 ; Wood, article " Pelvis" in the Cyclopaedia of
Anatomy and Physiology). The pelvic aspect of the sacrum, near its base,
looks much more downwards than forwards, hence the sacrum appears at
first sight to occupy the position of the keystone of an arch ; but being in
reality broader at its pelvic than on its dorsal aspect, it is a keystone
inverted or having its broad end lowest, and is only supported in its place
by cartilage and ligaments. The line of pressure of the weight of the body
on the sacrum is directed downwards towards the symphysis pubis, and the
resistance of the head of the thighbone on each side is directed upwards and
inwards: hence in the most frequent deformities of the pelvis, arising from
Fig. 89. Figs. 89 and 90.
SKETCHES OF THE MALE
AND FEMALE PELVIS.
As seen from above
and in front, or at right
angles to the brim of
the true pelvis : de-
signed farther to illus-
trate the differences of
the male and female
form, and showing in
the lower figure of the
female pelvis the lines
in which the dimensions
of the pelvis are usually
measured ; (these lines
are only marked on the
brim of the pelvis).
a, p, antero- posterior
or conjugate diameter;
t, r, transverse or
widest diameter ; o, b,
0, b, oblique diameters.
In the original speci-
mens, which were se-
lected as giving the full
average dimensions, the
following were the mea-
surements in inches :
Antero-posterior or
conjugate diameter
female, 4| ; male, 4.
Transverse diameter
female, 5\ ; male, 4.
Oblique diameter fe-
male, 5; male, 4.
insufficient strength of its walls, the sacrum is projected into the inlet of the
pelvis, and the acetabula approach the middle line, while the pubic bones
are pressed forwards and downwards between them.
Fig. 90
INCLINATION OF THE PELVIS.
99
The axis of the pelvis is the name given to a line drawn in the middle
at right angles to the planes of the brim, cavity and outlet. The posterior
wall, formed by the sacrum and coccyx, being about five inches long and
Fig. 91.
Fig. 92.
Fig. 91. VERTICAL ANTERO-
POSTERIOR SECTION OP A
FEMALE PELVIS, MADK
THROUGH THE SYMPHYSIS
PtJBIS AND MIDDLE OF
THE SACRUM AND COCCYX,
SHOWING THE LEFT LATERAL
HALF (reduced from Na-
gele's figure),
1, symphysis pubis ; 2,
base of the sacrum and pro-
montory ; 3, coccygeal bones ;
4, anterior superior spine
of ilium; 5, tuberosity of
ischium ; 6, spine of ischium
(the obturator foramen is not
represented so pointed below
as it generally is in females).
The vertical and horizontal
lines in the lower part of the
figure serve as standards of
comparison for the degree of
inclination of the pelvis, as
illustrated by the next
figure.
Fig. 92. SKETCH OF PART OF THE
PRECEDING FIGURE, SHOWING
THE INCLINATION OF THE BRIM
OF THE PELVIS AND ITS AXIS
IN THE ERECT POSTURE.
a, &, line of inclination of the
brim of the true pelvis from
above the symphysis pubis to the
promontory of the sacrum ; e, f,
a line inclining backwards and
upwards, touching the lower edge
of the symphysis pubis and point
of the coccyx ; c, d, axis of the
brim at right angles to the plane
of the brim ; from d to the dotted
line at right angles to e f, curved
axis of the cavity continued into
that of the outlet of the osseous
pelvis ; h, g, axis of the outlet
of the pelvis when the soft parts
are combined.
concave, while the anterior
wall at the symphysis pubis
is only one and a half or
two inches long, the axis is
curved : it is directed at the inlet upwards and forwards towards the um-
bilicus, and at the outlet downwards and a little forwards. The curvature
of the axis of the pelvis is specially important as indicating the course
in which the child's head is propelled in the process of parturition ; and
it may be mentioned that in the female pelvis with the soft parts entire, the
axis of the outlet is curved much more forwards than in the skeleton, the
H 2
100
BONES OF THE LOWER LIMB.
posterior wall being prolonged in that direction by the integuments of the
perineeum.
Differences according to Sex. The size and form of the pelvis differ
remarkably in the two sexes. In the female the constituent bones are
more slender and less marked with muscular impressions ; the perpendicular
depth is less, and the breadth and capacity greater ; the ilia are more ex-
panded than in the male ; the inlet of the true pelvis is more nearly circular,
the sacral promontory projecting less into it, and is broader from side to
side ; the depth of the symphysis pubis is less, the pubic arch is much
wider, and the space between the tuberosities of the ischia greater.
The average dimensions of the pelvis, as measured in a number of full-
sized males and females, may be stated as follows, in inches :
Distance between the widest part of the
crests of the ilia ....
Distance between the anterior superior
spines of the ilia ....
Distance between the front of symphysis
pubis and the sacral spines
TKUE PELVIS.
Transverse diameter ....
Oblique diameter . ....
Antero-posterior diameter .
MALE.
FEMALE.
10 to 11
94 10
64 - 7
104 to 11
10 104
64 - 74
Brim.
Cavity.
Outlet.
Brim.
Cavity.
Outlet.
44
4i
4
44
44
44
H9 -4*
CO "* CO
5k
5
44
5
5k
5i
11
5
THE FEMUK.
The femur or thigh bone, the largest bone of the skeleton, is situated
between the os innominatum and the tibia. In the erect position of the
body it inclines inwards and slightly backwards as it descends, so as to
approach inferiorly its fellow of the opposite side, and to have its upper
end a little in advance of the lower. It is divisible into a superior ex-
tremity, including the head and neck and two eminences called trochanters,
the shaft, and an inferior extremity expanded into an external and an in-
ternal condyle.
At the superior extremity of the bone, the neck extends inwards and
upwards, and has a slight inclination forwards from the shaft. It has a
constricted appearance, and its diameter from before backwards is less con-
siderable than in the vertical direction, in which last greater strength is
required to sustain the weight of the body. Its superior surface is shortest ;
its inferior surface longest, and the anterior shorter than the posterior. The
head, forming more than half a sphere, covered with cartilage in the fresh
state, surmounts the neck, and is articulated with the acetabulum. Beneath
its most prominent point is a small depression or pit, which gives attach-
ment to the round ligament of the hip joint.
The trochanter major is a thick truncated process prolonged upwards in
a line with the external surface of the shaft. In front it is marked by the
insertion of the gluteus minimus ; externally an oblique line directed down-
wards and forwards indicates the inferior border of the insertion of the
gluteus medius muscle, and lower down a horizontal line, continued upwards
in front of the trochanter, marks the upper limit of the vastus externus.
FEMUR,
101
Internally at its base, and rather behind the neck, is the trochanteric or digital
Fig. 93. FEMUR OF A MALE FROM BEFORE. Fi g-
1, shaft ; 2, head ; 3, neck ; 4, great tro-
chanter ; 5, small trochanter ; 6, anterior
inter-trochanteric line ; 7, internal articular
condyle; 8, external articular condyle; 9, in-
ternal tuberosity; 10, external tuberosity;
11, the patellar articular surface ; above it 12,
the flat part of the femur sometimes called the ^kf, v
suprapatellar surface ; 13, the depression for
the tendon of the popliteus muscle.
fossa, which gives attachment to the ob-
turator externus muscle. The posterior
border of the great trochanter is pro-
minent, and continued into a smooth
elevation, the posterior inter trochanteric
line, which passes downwards and in-
wards to the small trochanter, and limits
the neck posteriorly. The small tro-
chanter, a conical rounded eminence,
projects from the posterior and inner
aspect of the bone, and gives attach-
ment to the tendon of the psoas and
iliacus muscles. The anterior intertro-
chanteric line is a rough ridge limiting
the neck in front between the two tro-
chanters ; it indicates the superior border
of the crureus and vastus internus mus-
cles, and is continuous beneath the great
trochanter with the line which limits
the vastus externus.
The shaft is slightly arched from above
downwards, with the convexity forwards.
It is expanded at its upper and lower
ends. Towards the centre it is nearly
cylindrical, but with an inclination to
the prismatic form. Its anterior and
lateral surfaces, smooth and uniform, are
covered by the crureus and vasti muscles.
The elevation which separates the ante-
rior from the internal surface is at the
upper part strongly marked and inclined
forwards, giving the appearance to the
bone as if the forward inclination of the
neck were produced by a twisting out-
wards of the upper end of the shaft.
The lateral surfaces in the middle of their
extent approach one another behind, being
only separated by the linea aspera. The
linea aspera is a prominent ridge, extend-
ing along the central third of the shaft
posteriorly, and bifurcating above and 7
below. It inclines slightly inwards in the middle, so as to make the external
102
BONES OF THE LOWER LIMB.
iv-
surface of the shaft seem concave in that part. It presents two sharp
Fig. 94. Fig. 94. FEMUR OF A MALE PROM BEHIND. ^
"~*X 4 5 > 7, 8, 9, 10 and 13, the same as in the
preceding figure ; 2', pit on the head for the
round ligament of the hip-joint ; 3', the back of
the neck, showing a slight groove of the obturator
externus muscle as it passes over the capsular
ligament and neck; 14, rough impression of the
attachment of the gluteus maximus muscle in the
upper and outer continuation of the linea aspera ;
15, two lines running up towards the lesser tro-
chanter from the linea aspera, marking the
attachments of the adductor brevis and pectineus
muscles; 16, flat elevated surface of the linea
aspera ; 17, flat triangular popliteal surface
between the lower divisions of the linea aspera ;
18, intercondyloid or crucial notch ; 19, foramen
for the nutritious or medullary vessels.
margins and a flat interval. The external
division of its superior bifurcation passes
up to the great trochanter, and in its
course is strongly marked where the
gluteus maximus is attached ; the internal
division terminates in front of the small
trochanter. The inferior divisions termi-
nate at the tuberosities of the condyles,
and enclose between them a flat triangular
surface of bone, which is free from mus-
cular attachments, and forms the floor of
the upper part of the popliteal space.
Towards the superior part of the linea
aspera is the foramen for the medullary
vessels, directed upwards into the bone.
The inferior extremity presents two
rounded eminences, the condyles, united
anteriorly, but separated posteriorly by a
deep intercondyloid fossa. Their greatest
prominence is directed backwards, and
their curve, as it increases towards that part,
may be compared to that of a partially
uncoiled piece of watch-spring. The ex-
ternal condyle is the broader and more
prominent in front ; the internal is the
longer and more prominent inferiorly.
One large articular surface, coated con-
tinuously with cartilage, extends over both
\ \\1\V condyles, but, opposite the front of the
intercondyloid fossa, it is divided by two
slight linear depressions into three parts,
an elevated surface on each side of the
fossa for articulation with the tibia ; and
a grooved anterior surface for the patella.
The patellar surface is of a trochlear form,
being marked by a vertical hollow ; the
external portion of this surface is the most prominent, and rises highest.
PATELLA. TIBIA. 103
The tibial surfaces are nearly parallel, except in front, where the internal
turns obliquely outwards to reach the patellar surface. Above the condyles
are two rough tuberosities, one on each side of the bone, which give attach-
ment to the external and internal lateral ligaments of the knee joint.
Between the external tuberosity and the back part of the external condyle
is a smooth groove directed downwards and forwards, and ending anteriorly
in a pit, in which the popliteus muscle takes origin.
In the female the angle made by the neck of the femur with the shaft is less
obtuse than in the male; and from the greater width of the pelvis, and the shortness
of the limbs, the convergence of the thigh bones inferiorly is more apparent.
THE PATELLA.
The patella, rotula, or knee-pan, is situated at the front of the knee
joint, is attached inferiorly by a ligament or tendon to the tibia, and may be
Fig. 95. RIGHT PATELLA. ^ Fj g> 95.
A from before ; B from behind.
Both views show the lower extremity pointing slightly inwards ;
the posterior view shows the articular cartilaginous surface, divided
by an elevated ridge into a smaller internal and a larger external
part.
considered as a sesamoid bone developed in the tendon of
the quadriceps extensor cruris. It is compressed from
before backwards, and has the form of a triangle with the
apex below. Its anterior surface is subcutaneous; its
superior border is broad, and gives attachment to the
extensor muscles; its inferior angle, together with a
rough depression on its deep aspect, gives attachment to
the ligainenturn patellae. The deep surface, except at the
inferior angle, is coated with cartilage for articulation with
the femur, and is divided by a vertical elevation into two
parts, the external of which is the larger and is transversely concave, while
the internal is convex.
THE TIBIA.
The tibia, or shin bone, is, next to the femur, the longest bone in the
skeleton. It is the anterior and inner of the two bones of the leg, and
alone communicates the weight of the trunk to the foot. It articulates with
the femur, fibula, and astragalus.
The superior extremity is thick and expanded, broader from side to side
than from before backwards, and slightly hollowed posteriorly. On its
superior aspect are placed two slightly concave articular surfaces, which
sustain the femur. These are the condyloid surfaces; they are oval in form,
the external being widest transversely, and the internal longest from
before backwards. Between them is an irregular interval, depressed in
front and behind, where it gives attachment to the crucial ligaments
and semilunar cartilages of the knee joint, and elevated in the middle,
where is formed the spine. The summit of the spine presents two
prominent tubercles, which are formed by the prolongation upwards on
its sides of the margins of the condyles ; that of the outer coudyle being
turned slightly forwards, and that of the inner more slightly backwards.
On the sides of the upper extremity of the bone are two rounded
eminences, the external and internal tuber osities the outer one of these,
104
BONES OF THE LOWER LIMB.
somewhat smaller than the other, is marked posteriorly by a flat surface
which articulates with the fibula, while the inner presents a groove for
the insertion of the semi-membranosus muscle. Lower down, in front, is
situated the anterior tuberosity or tubercle, rough inferiorly, where it gives
attachment to the ligamentum patellee, and smooth above, where it is
covered by a synovial bursa.
Fig.
Fig. 96. EIGHT TIBIA FROM BEFORE.
1, shaft, and shin or anterior border ; 2, inner tube-
rosily ; 3, outer tuberosity ; 4, inner, and 5, outer,
condyloid articular surface ; 6, crucial spine, with fossa
at its root in front ; 7, anterior tuberosity or tubercle ;
8, lower articular surface for astragalus ; 9, malleolus
iuternus.
The shaft of the tibia is three-sided, and
diminishes in size as it descends for about two-
thirds of its length, but increases somewhat
towards its lower extremity. The internal sur-
face is convex and subcutaneous, except at the
upper part, where it is crossed by the tendons
of the sartorius, gracilis, and semitendinosus
muscles. It is separated from the external sur-
face by a sharp subcutaneous, slightly sinuous
crest, the shin ridge, which descends from the
anterior tuberosity, and is smoothed away in the
inferior third of the bone. The external surface
is slightly hollowed in the larger part of its
extent, where it gives origin to the tibialis
anticus muscle ; but beneath the point where the
crest disappears it turns forwards, becomes
convex, and is covered by the extensor tendons.
The posterior surface is traversed obliquely in its
upper third by the popliteal line a rough mark
which extends upwards and outwards to the
external tuberosity, giving attachment to the
soleus muscle, and separating a triangular area,
in which the popliteus muscle lies, from the
space below, which gives origin to the flexor
longus digitorum and tibialis posticus. Inter-
nally, the posterior surface is separated from the
internal by a smooth rounded border; while on
its external side is a sharp ridge, inclined
forwards above, to which the interosseous mem-
brane is attached. Near the popliteal line is a
u\ large medullary foramen, directed downwards
into the interior of the bone.
The inferior extremity, much smaller than the
superior, is expanded transversely, and projects
downwards on its inner side, so as to form a
thick process, the internal malleolus. Inferiorly it presents for articulation
with the astragalus a cartilaginous surface, which is quadrilateral, concave
from before backwards, and having its posterior border narrower and pro-
TIBIA. FIBULA.
105
jecting farther downwards than the anterior; internally the cartilaginous
surface is continued down in a vertical direction upon the internal malleolus,
clothing its outer surface somewhat more deeply in front than behind. The
Fig. 97. RIGHT TIBIA PROM BEHIND. ^ Fig. 97.
6, and 9, as in the preceding figure ; 2', groove behind 6
the internal tuberosity for the tendon of the semi-mem-
branosus muscle ; 10, inclined articular facet below and
behind the outer tuberosity for the head of the fibula ;
11, oblique line of tibia, above which is the triangular
popliteal surface ; 12, foramen directed downwards for
the nutritious or medullary vessels ; 13, triangular rough
surface for the lower interosseous ligament and small
cartilaginous surface below it for articulation with the
fibula; 14, below a slight groove marking the place of
the flexor longus pollicis muscle ; 15, below the groove
of the tendons of the flexor communis digitorum and
tibialis posticus muscles, behind the malleolus internus.
-12
external surface, slightly concave, is rough
superiorly for ligament, and smooth below for
articulation with the fibula. The posterior sur-
face is marked by a double groove on the in-
ternal malleolus for the tendons of the tibialis
posticus and flexor longus digitorum, and more
externally by a slight depression where the flexor
longus pollicis lies; the inner surface of the
internal malleolus is subcutaneous.
The tibia is slightly twisted, so that when the
internal malleolus is directed inwards, the in-
ternal tuberosity is inclined backwards a con-
formation which deserves attention in the
diagnosis and adjustment of fractures.
THE FIBULA.
The fibula, or peroneal bone, is situated at the
external side of the leg : it is nearly equal to
the tibia in length, but is much more slender.
Its inferior extremity is placed a little in advance
of the upper; and its shaft is slightly curved,
so as to have the convexity directed backwards,
and, in the lower half, slightly inwards towards
the tibia.
The superior extremity, or head, somewhat ^|I^U
expanded, presents a small oval cartilaginous
surface looking upwards and inwards, which
articulates with the external tuberosity of the
tibia, and externally to this a rough prominence directed upwards, to
which the tendon of the biceps muscle is attached: its external surface is
subcutaneous ; the rest is rough for ligaments.
The inferior extremity or external malleolus, is larger than the head of
the bone, and longer and more prominent than the internal malleolus ;
internally it forms the outer limit of the ankle joiut, and presents a triangular
smooth surface for articulation with the astragalus, bounded posteriorly by
a rough depression where the transverse ligament is attached : its anterior
106
BONES OF THE LOWER LIMB.
border, after projecting rather abruptly forwards, slopes downwards and
backwards ; its posterior border presents a shallow groove traversed by the
tendons of the peronei muscles ; while externally it is convex and subcu-
taneous, and a triangular subcutaneous surface is continued up from it for
an inch or two on the shaft.
Fig. 98.
Fig. 99.
5
Fig. 98. RIGHT FIBULA PROM THE OUTSIDE AND
BEFORE.
1, shaft, outer and anterior surface, showing the
oblique grooves of the peronei muscles ; 2, head ; 3, its
projection, giving insertion to the tendon of the biceps
feraoris ; 4, malleolus externus or lower end, the figure
is placed opposite its anterior or oblique edge ; above this
is seen the triangular subcutaneous surface of the bone.
Fig. 99. RIGHT FIBULA FROM THE INSIDE AND
BEHIND. |
5, the oblique surface of articulation with the tibia
superiorly ; 6, points to the internal or interosseous
ridge ; 7, the triangular rough surface for the lower
interosseous ligament ; 8, the external malleolar surface
for articulation with the astragalus ; 9, groove behind
the malleolus externus for the tendons of the peronei
muscles.
The shaft is irregularly three-sided and
twisted. One surface, from which the peronei
muscles take origin, looks forwards at the com-
mencement, then, turning outwards and back-
wards, is continued behind the subcutaneous
space of the lower end to the groove behind the
malleolus. Another surface, looking backwards
in the upper half of its extent, winds inwards
and terminates above the articular surface of
the malleolus; near its upper end this surface
is rough, giving attachment to the soleus
muscle, and in the rest of its extent it is occu-
pied by the flexor longus pollicis. The remain-
ing part of the surface of the bone, internal,
turns forwards inferiorly, and terminates on the
anterior margin of the malleolus : it is divided
by a longitudinal line, the interosseous ridge,
into a posterior and upper part, which gives
origin to the tibialis posticus, and an anterior
and lower part, from which arise the long ex-
tensors of the toes and the peroneus tertius,
the interosseous membrane being attached to
the line between these surfaces. About the
middle of the posterior surface is the medullary
foramen directed downwards into the bone.
THE TARSUS.
The tarsus is composed of seven bones, viz., the os calcis, astragalus,
cuboid, scaphoid, and three cuneiform.
TARSAL BOXES.
107
THE CALCANEUM.
The calcaneum, or os calcis, is the largest bone of the foot. Projecting
downwards and backwards, it forms the heel. Above it articulates with the
astragalus, and in front with the cuboid bone. Its principal axis extends
forwards and outwards from its posterior extremity to the cuboid bone.
Fig. 100. RIGHT FOOT VIEWED FROM ABOVE, SHOWING Fig. 100.
ITS DORSAL ASPECT. ^
a, scaphoid bone ; 6, astragalus ; c, os calcis ; d, its
great tuberosity ; e, internal or first cuneiform ; /, middle
cuneiform ; g, external cuneiform ; h, cuboid bone. I to
V, the series of metatarsal bones ; 1, 3, first and terminal
phalanges of the great toe ; 1, 2, 3, are placed opposite to
the first, second, and terminal phalanges of the second toe.
The large posterior extremity, or tuber calcis,
presents inferiorly two tubercles, which rest upon
the ground, and the internal of which is the
larger : the rest of its surface, looking backwards,
is divided into a lower part, which receives the
attachment of the tendo Achillis, and an upper
part, smooth and less prominent, separated from
that tendon by a synovial bursa. The part in
front of the tuber forms a slightly constricted
neck. The internal surface of the bone, traversed
by the plantar vessels and nerves and the flexor
tendons, is deeply concave, and its concavity is
surmounted in front by a flattened process, the
sustentaculum tali, which projects inwards near
the anterior extremity of the bone, in a line with
its upper surface, and presents inffcriorly a groove
occupied by the tendon of the flexor longus pollicis.
The superior surface presents two articular facets
for the astragalus : the anterior of these is placed
over the sustentaculum, and is flat ; the other, external and posterior to
this, and larger, is separated from it by a rough furrow, giving attachment
to the inter osseous ligament, and is convex from without inwards and back-
wards. In front of this latter facet is a rough depression, from which the
extensor brevis digitorum takes origin. The anterior extremity articulates,
by a surface slightly concave in the vertical and convex in the transverse
direction, with the cuboid bone ; and internal to this, in front of the sus-
tentaculum tali, it gives attachment to the inferior calcaneo-scaphoid ligament.
The inferior surface, projecting in a rough anterior tubercle, gives attach-
ment to the calcaneo-cuboid ligaments. The external surface is subcutaneous,
and on the whole smooth, but presents in its fore-part superficial grooves
traversed by the tendons of the peronei muscles.
THE ASTRAGALUS.
The astragalus or talus, irregular in form, receives the weight of the body
from the leg. It articulates with the tibia and fibula above, the os calcis
below, and the scaphoid in front. Its longest axis is directed forwards and
inwards. Its convex anterior extremity is called the head, and the circular
groove behind it the neck. The superior articular surface, placed behind
108
BONES OF THE LOWER LIMB.
the neck, consists of a middle and two lateral parts. The middle part,
looking upwards to the tibia, is convex from before backwards, broader in
front than behind, with its outer margin higher and longer than the inner,
and curved, while the inner is straight. The inner lateral part is narrow,
and articulates with the internal malleolus ; the outer lateral part, much deeper,
articulates with the external malleolus. Inferiorly, there are two smooth
surfaces, which articulate with the calcaneum. The posterior of these, the
larger, concave from within outwards and forwards, is separated by a
rough depression for the interosseous ligament from the flat anterior sur-
face, which rests on the sustentaculum tali. The anterior margin of this
surface is continuous with the rounded surface of the head, which articulates
with the scaphoid bone. The posterior border of the bone lies behind the
sustentaculum tali, and, like that process, is grooved by the tendon of
the flexor longus pollicis.
Fig. 101. Fig. 101. RIGHT FOOT VIEWED FROM BELOW, SHOWING
THE PLANTAR ASPECT. ^
The indications are the same as in the preceding figure ;
the middle and external cuneiform bones are not lettered ;
the sesamoid bones are not represented ; they will be seen
in the view of the articulations of the foot.
THE CUBOID BONE.
This bone is situated at the outer side of the
foot, between the calcaneum and the fourth and
fifth metatarsal bones. It deviates from the cuboid
form and becomes rather pyramidal, by the sloping
of four of its surfaces towards the smaller external
border. The posterior cartilaginous surface articu-
lates with the os calcis ; the anterior surface, also
covered with cartilage, is divided into an internal
quadrilateral and an external triangular facet, ar-
ticulating with the fourth and fifth metatarsal
bones. On the internal aspect, in the middle, and
touching its superior border, is a smooth surface,
which articulates with the external cuneiform
bone, and behind this, in some instances, a smaller
surface articulating with the scaphoid, while
the remainder is rough for ligaments. The exter-
nal border presents a vertical groove, in which the
tendon of the peroneus longus lies ; and the inferior
surface is traversed obliquely near its anterior mar-
gin by a continuation of the same groove ; behind this there is a thick ridge,
which, with the rest of the inferior surface, gives attachment to the calcaneo-
cuboid ligaments. The superior surface, looking outwards and upwards, is
on the whole even, but rather rough.
THE SCAPHOID BONE.
The scaphoid or navicular bone is placed at the inner side of the foot
between the astragalus and cuneiform bones. It is short from behind
forwards, and broad from side to side. It presents posteriorly an articular
concavity for the head of the astragalus, and anteriorly a convex surface
divided, by two lines converging below, into three facets which articulate
METATARSAL BONES. 109
respectively with the three cuneiform bones. On its outer side, in some
instances, is a small smooth surface, by which it is articulated to the cuboid
bone. Its superior and inferior surfaces are rough, and on its inner border,
directed downwards, is a prominent tubercle to which the tendon of the
tibialis posticus muscle is attached.
THE CUNEIFORM BONES.
These wedge-shaped bones, three in number, are distinguished numerically
according to their order from within outwards. They intervene between the
scaphoid bone and the three inner metatarsal bones, and present anteriorly
and posteriorly smooth surfaces for articulation with those bones. The first
or internal cuneiform bone is the largest ; it is narrow above, and thick
and rough towards the sole ; its dorsal surface looks inwards and upwards,
and is marked by an oblique descending groove, in which the tendon of the
tibialis anticus lies ; its external surface, concave and rough inferiorly, is
smooth and articular above. The second and third, or middle and ex-
ternal, cuneiform bones each present a quadrangular surface superiorly, and
a narrower rough edge below, contributing thus to form the transverse arch
of the foot. The proximal ends of the three bones are in the same transversa
line ; but as the middle bone is the shortest, the internal and external
project forwards, so as to articulate laterally not only with the sides of that
bone, but also with the base of the second metatarsal bone, which is inserted
between them. The outer side of the third cuneiform articulates by a
smooth flat surface with the cuboid, and by a small narrow facet (some-
times absent) with the fourth metatarsal bone.
THE METATARSUS.
The five metatarsal bones are distinguished by numbers, according to
their position from within outwards.
They resemble the metacarpal bones of the hand in being shafted bones,
slightly convex from behind forwards on the dorsal aspect, and having
irregularly shaped proximal extremities, three-sided shafts, and rounded
heads which articulate with the phalanges. The first metatarsal bone is
much thicker and more massive, though shorter, than any of the rest. The
others diminish in length from the second to the fifth.
The proximal extremities resemble those of the metacarpal bones exactly
as regards the number of bones with which each articulates. The first
articulates with one bone, the internal cuneiform ; the second with four
bone?, viz. the three cuneiform and the third metatarsal ; the third with
three bones, viz. the external cuneiform and the adjacent metatarsals ; the
fourth with four bones, viz. the cuboid, external cuneiform, and the adjacent
metatarsals ; the fifth with two bones, viz. the cuboid and the fourth meta-
tarsal. The fourth, however, is sometimes connected with only three bones,
its facet for articulation with the external cuneiform being absent. The
tarsal extremity of the first metatarsal bone presents a slightly concave
articular surface, and is broad below and narrow above. That of the fifth
presents externally a large rough tuberosity which projects beyond the other
bones at the outer side of the foot ; and the line of its articulation with the
cuboid bone is so oblique that, if prolonged inwards, it would reach the
digital end of the first metatarsal bone. The tarsal ends of the remaining
three bones are broad and flat above, rough and narrower below, and by
their wedge-like form assist in producing the transverse arch of the foot.
The shafts present in the greater part of their extent a prominent border
110 BONES OF THE LOWER LIMB.
looking upwards, which in the middle three projects between the dorsal
interosseous muscles on each side.
The heads, smaller than the tarsal extremities, are marked on their sides
by depressions and tubercles. Their articular surfaces, smooth and convex,
are prolonged on the inferior aspect, where they terminate in bifid margins.
That of the first metatarsal bone presents inferiorly a ridge in the middle,
with grooved depressions placed one on each side and corresponding to the
position of the sesamoid bones.
THE PHALANGES.
The phalanges of the toes so closely correspond in general conformation
with those of the fingers that it will only be necessary in this place to state
the points in which they differ from the latter.
The phalanges of the four outer toes are much smaller than the corres-
ponding phalanges of the hand ; but those of the great toe are larger than
those of the thumb. The shafts of the first row of phalanges in the four
outer toes are compressed laterally and narrowed in the middle ; those of
the second row, more especially the fourth and fifth, are very short, and
consist of little beyond what is necessary to unite their articular extremities.
The last two phalanges of the little toe are in adults not unfrequently
connected by bone into one piece.
SESAMOID BONES. Two sesamoid bones lie side by side in the plantar
wall of the first metatarso-phalangeal joint, and glide in the grooves on the
head of the first metatarsal bone. Small sesamoid bones sometimes occur
in the corresponding joints of the other toes.
THE BONES OF THE FOOT AS A WHOLE.
The foot is narrowest at the heel, and as it passes forwards becomes
broader as far as the heads of the metatarsal bones. The posterior extremity
of the calcaneum is inclined inwards and backwards. The astragalus,
overhanging the sustentaculum tali, inclines inwards from the calcaneum so
much that its external superior angle is directly over the middle line of the
calcaneum, and hence the internal malleolus appears more prominent than
the external. The foot is arched from behind forwards, the posterior pier
of the arch being formed by the heel, the anterior by the balls of the toes.
The arch, indeed, may be considered as double in front, with a common
support behind. The internal division of the arch is that which bears the
greater part of the weight of the body, and is most raised from the ground ;
it consists of the calcaneum in its posterior two thirds, the scaphoid and
cuneiform bones, and the three inner toes ; the outer arch is formed by the
calcaneum in its whole length, the cuboid bone, and the fourth and fifth
toes, a great part of which rests upon the ground in standing. Besides being
arched longitudinally, the foot presents likewise a transverse arch formed by
the cuboid and three cuneiform bones and the metatarsal bones.
DEVELOPMENT OF THE LOWER LIMB.
The early stages of development in the lower limbs are similar to those which have
been already described in connexion with the upper.
OSSIFICATION. The innominate bone is formed from the three principal pieces
previously mentioned, viz., the ilium, ischium, and os pubis, and various others of an
epiphysal nature. The deposit of bone commences in the cartilaginous piece of the
ilium a little later than in other large bones ; it is followed by that in the ischium,
and still later by that in the pubis. One epiphysis extends over the whole length of
the crest of the ilium ; a second covers the tuberosity of the ischium, passing forwards
OSSIFICATION OF THE LOWER LIMB.
Ill
over the greater part of the ramus; a third, inconstant, is placed on the anterior inferior
spine of the ilium ; and a fourth, likewise inconstant, at the symphysis pubis. More-
over, between the extremities of the three principal osseous pieces, where they meet
in the acetabulum, there is situated in early life a thin stratum of cartilage, which
becomes ossified from one or more centres, and presents the shape of the letter Y.
Fig. 102.
Fig. 102. OSSIFICATION OF THE Os INNOMINATTJM.
A, the condition of the bone at birth. Bone has spread from three nuclei into the
ilium, ischium, and pubis, which meet in the cartilage of the acetabulum.
B, the bone of a child under six years of age. The rarni of the ischium and pubis are
farther ossified, but still separate.
C, a bone of two or three years later, in which the rami are united.
D, the bone of the right side from a person of about twenty years. Union has taken
place in the acetabulum, and the additional epiphyses are seen on the crest of the ilium,
the anterior inferior spine, the ischial tuberosity, and the margin of the symphysis pubis.
In A, B and C, 1, ilium ; 2, ischium ; 3, pubis ; under D, 4, T-shaped piece formed of
several fragments which begin to ossify about the 14th year, and often unite into this
form before the completion of the acetabulum ; 5, epiphysis of the crest ; 6, that of the
tuberosity of the ischium ; 7, that of the symphysis pubis ; 8, that of the anterior inferior
spine of the ilium.
The pelvis of the foetus and young child is of very small capacity proportionally
to the size of the body, and those viscera which are afterwards contained for the
most part in the true pelvis occupy a part of the abdominal cavity. The obliquity of
the pelvis is considerably greater in early life than in the adult.
The/em?/?' is developed from one principal ossific centre for the shaft and from
four epiphyses, which appear in the following order : a single nucleus for the lower
extremity, one for the head, one for the great trochanter, and one for the small ;
these epiphyses become united to the main part of the bone in an order of time the
reverse of that in which they appear.
The tibia and fibula each present, besides the principal centre of ossification for
the shaft, a superior and an inferior epiphysis. In the tibia the superior epiphysis
appears first, and it not only includes the lateral tuberosities, but sends down a pro-
cess in front, extending into the anterior tuberosity. In the fibula the inferior epi-
physis is the first to appear, and in both bones the inferior epiphyses are first united
to the shaft.
The tarsal bones are ossified each from a single nucleus, with the exception of the
os calcis, which, in addition to its principal osseous centre, has an epiphysis incrusting
the upper part of its posterior extremity.
The metatarsal bones and phalanges agree respectively with the corresponding
bones in the hand, in the mode of their development. Each bone is formed from a
principal piece and one epiphysis ; and while in the four outer metatarsal bones the
epiphysis is at the distal extremity, in the metatarsal bone of the great toe and in
the phalanges it is placed at the proximal extremity.
112
BONES OF THE LOWER LIMB.
PERIODS OF OSSIFICATION OF THE BONES OF THE LOWER LIMB.
I. Os Innominatum.
The chief nucleus of the ilium appears in the 8th or 9th week.
The chief nucleus of the ischium appears in the third month.
The chief nucleus of the pubis appears from the 4th to the 5th month.
Ossification in the Y-shaped cartilage of the acetabulum appears about puberty ;
and in the epiphysis of the iliac crest, anterior inferior spinous process, ischial
tuberosity, and symphysis pubis somewhat later.
The rami of the pubis and ischium unite about the 7th or 8th year.
The parts which meet in the acetabulum unite about the 16th or 17th year.
The main bone and epiphyses unite about the 25th year.
Fig. 103.
Fig. 103. OSSIFICATION OF THE FEMUR.
A, femur of a foetus of about eight months ; the body is osseous ; both ends are
cartilaginous.
B, femur of a child at birth, showing a nucleus in the lower epiphysis.
C, femur of a child of about a year old, showing a nucleus in the articular head.
D, femur of the fifth or sixth year. Ossification has extended from the shaft into the
neck, and a nucleus has appeared in the great trochanter.
E, femur of about the age of puberty, showing more complete ossification and a nucleus
in the lesser trochanter.
1, shaft ; 2, lower extremity ; 3, head ; 4, great trochanter ; 5, small trochanter.
II. Femur.
The nucleus of the shaft appears in the 7th week.
The nucleus of the lower epiphysis appears in the 9th month.
The nucleus of the head appears at the end of the 1st year.
The nucleus of the great trochanter appears in the 4th year.
The nucleus of the small trochanter appears in the 13th or 14th year.
The small trochanter and shaft unite about the 17th or 18th year.
The great trochanter and shaft unite about the 18th year.
The head and shaft unite about the 18th or 19th year.
The lower epiphysis and shaft unite after the 20th year.
III. Tibia.
The nucleus of the shaft appears in the 7th week.
The upper epiphysis appears sometimes before, sometimes after birth.
OSSIFICATION OF TIBIA AXD FIBULA,
Fig. 104.
C
113
Fig. 104. OSSIFICATION OF THE TIBIA.
A, tibia of a foetus some weeks before birth ; the shaft is ossified ; the ends are
cartilaginous.
B, tibia of a child at birth, showing the commencement of a nucleus in the upper
epiphysis.
C, tibia of the third year, showing the nucleus of the lower epiphysis.
D, tibia of about eighteen or twenty years, showing the united condition of the lower
epiphysis, while the upper remains separate. The upper epiphysis is seen to include the
anterior tuberosity.
E shows an example of a separate centre for the anterior tuberosity.
1, shaft; 2, superior epiphysis ; 2', separate centre for the anterior tuberosity; 3,
inferior epiphysis.
Fig. 105.
Fig. 105. OSSIFICATION OF THE FIBULA.
A, fibula from a child at birth. The shaft ossified ; the ends cartilaginous.
B, fibula from a child of two years, showing a nucleus in the lower epiphysis.
C, the bone of a child of about four years, showing the nucleus of the upper epiphysis ;
the lower ought to have been shown as more advanced.
D, fibula of a person of about twenty years, in which the lower end is complete, but
the upper epiphysis is still separate.
1, shaft; 2, lower epiphysis ; 3, upper epiphysis.
i
114
BONES OF THE LOWER LIMB.
Fig. 106.
c
D
Fig. 106. OSSIFICATION OF THE BONES OF THE FOOT.
A, right foot of a foetus of six months. The metatarsal bones and digital phalanges
have each their shafts ossified from their primary centres ; the tarsus is wholly cartila-
ginous, excepting the os calcis, in which the nucleus of bone has just appeared.
B, foot of a foetus of from seven to eight months. The astragalus shows an osseous
nucleus.
C, from a child at birth ; the cuboid has begun to ossify.
D, from a child about a year old, showing a nucleus begun in the external cuneiform.
E, from a child in the third year ; ossification has reached the internal cuneiform.
F, from a child between three and four years old, showing ossification in the middle
cuneiform and scaphoid bones, and in the epiphyses of the metatarsal bones and phalanges.
Of, from a person of about the age of puberty. Ossification is nearly complete in the
tarsal bones ; an epiphysis has been formed on the tuberosity of the os calcis, and the
epiphyses of the metatarsal bones and phalanges are shown separate.
1, nucleus of the os calcis; 1* in G, the epiphysis of the os calcis ; 2, nucleus of the
astragalus ; 3, of the cuboid ; 4, of the external cuneiform ; 5, of the internal cuneiform ;
6, of the scaphoid ; 7, of the middle cuneiform ; 8, metatarsal bones ; 8*, distal epiphyses
of the four metatarsal bones ; 8', proximal epiphysis of the first ; 9, first range of digital
phalanges; 9*, proximal epiphyses of the four outer of these phalanges ; 9', that of the
first phalanx of the great toe ; 10, second range of phalanges ; 10*, the epiphyses of these
phalanges; 10', epiphysis of the terminal phalanx of the great toe; 11, four terminal
phalanges; 11*, their epiphyses.
UPPER AND LCAVER LIMBS COMPARED. llo
Tibia (continued)
The lower epiphysis appears in the 2nd year.
The lower epiphysis and shaft unite in the 18th or 19th year.
The upper epiphysis and shaft unite in the 21st or 22nd year.
IV. Fibula.
The nucleus of the shaft appears soon after that of the tibia.
The lower epiphysis appears in the 2nd year.
The upper epiphysis appears in the 3rd or 4th year.
The lower epiphysis and shaft unite in the 21st year or later.
The upper epiphysis and shaft unite after union of the lower epiphysis.
V. Patella.
Ossification begins in the 3rd year,
VI. Tarsus.
The nucleus of the os calcis appears in the 6th month.
The nucleus of the astragalus appears in the 7th month.
The nucleus of the cuboid bone appears at birth.
The nucleus of the external cuneiform bone appears in the 1st year.
The nucleus of the internal cuneiform bone appears in the 3rd year.
The nucleus of the middle cuneiform bone appears in the 4th year.
The nucleus of the scaphoid bone appears in the 4th or 5th year.
The epiphysis of the os calcis appears in the 10th year.
The epiphysis of the os calcis is united, in the 15th or 16th year.
VII. Metatarsus.
The nuclei of the shafts appear in the 8th or 9th week.
The epiphyses appear in the 3rd to the 8th year.
The shafts and epiphyses unite from the 18th to the 20th year.
VIII. Phalanges.
The nuclei of the shafts appear in the 9th or 10th week.
The epiphyses appear from the 5th to the 8th year.
The shafts and epiphyses unite from the 19th to the 21st year.
COMPARISON OF THE UPPER WITH THE LOWER LIMB.
The general resemblance which is manifest between the upper and lower limbs is
found, on a closer inspection, to result from a community of plan, which can be
traced even into certain comparatively minute details, and is not confined to any one
system. The details of the correspondence in many points, however, are still un-
determined, and even with regard to some parts of the skeleton, variety of opinion still
exists. In the hand and foot the correspondence of the bones is very plain. The
palmar and plantar aspects being regarded as similar, the great toe corresponds
obviously to the thumb ; the four anterior tarsal bones bear a close resemblance to the
four inferior carpal bones in the particulars of their metatarsal articulations ; and
of the remaining tarsal bones the scaphoid obviously corresponds to the bone of the
same name in the hand, the astragalus to the semilunar bone, and the os calcis to
the cuneiform and pisiform bones united. The great difference in the appearance of
the tarsus from that of the carpus depends principally on the large development
of the os calcis and astragalus, by means of which the scaphoid is thrown for-
ward and inwards, and the aspect of the tarsus morphologically posterior, that on
which the flexor tendons pass to the sole, is turned towards the inner side. If
this be the correct comparison of the bones of the hand and foot, with regard to
which there cannot be any doubt, it naturally follows that the tibia, lying as it does
on the same side of the limb as the great toe, corresponds with the radius : a doctrine
which, first laid down by De Blainville and then by Barclay, has been subsequently
enunciated by Flourens and Owen. Some anatomists, however, struck by the resem-
blance of the patella to the olecranon, in position and in giving attachment to an ex-
tensor muscle similar in appearance to the triceps extensor brachii, have taken a dif-
ferent view ; thus, according to Vicq D'Azyr, the tibia corresponds with the ulna of
the opposite side of the body, while, according to Bourgery, Cruveilhier, and Martins,
its upper end corresponds with the ulna and its lower end with the radius of the
i2
116 BONES OF THE LIMBS.
same side of the body. This latter hypothesis must be regarded as particularly
unhappy, as it is difficult to conceive how any substantial homology, or a resem-
blance other than fanciful, can be traced by imagining half of a bone to correspond
with one structure, and the other half with a structure totally different. Equally
artificial is the proposition of Vicq D'Azyr to compare the upper limb of one side
with the lower limb of the other side of the body. The assumed correspondence
of the olecranon and patella, which has led to those theories, is not borne out by a
comparison of the development of the two structures. The patella is formed, distinct
from the tibia, as a sesamoid bone in a tendon, while the olecranon is mainly derived
from the principal centre of ossification of the ulna, and is formed only in part by the
superior epiphysis of that bone. In support of the more probable view, that the ulna
corresponds with the fibula, it is to be noticed that in the echidna and some other
animals the head of the fibula is prolonged upwards into a process which much more
closely corresponds with the olecranon than does the patella. It may also be observed
that in certain mammals, such as the bear or other plantigrades, in which there is a
power of partial pronation, the radius crosses the forearm obliquely, and its upper
end is brought somewhat in front of the ulna; while in the greater number of
mammals, in whi'ch there is no power of pronation or supination, the radius is
placed entirely to the front and internally, and the ulna is thrown to the outside
and behind, in the same manner as the fibula is to the outside of and behind the
tibia ; and the resemblance between the respective bones in the fore and hind
limbs is made the more striking that the radius and tibia are in these animals
generally the principal bones, while the ulna and fibula are in many species only
partially developed. An examination of the fore limb in a series of animals shows
that the articulation of the radius, as in man, with a separate portion of the
humerus external to that with which the ulna articulates is quite exceptional, the
most common arrangement being that the ulna forms the posterior and the radius
the anterior part of one great sigmoid cavity similar to that formed by the ulna in
the human subject. In comparing the humeral with the femoral region it may be
well to have regard to the apparent twist inwards which is seen in both femur and
humerus, and especially in the latter bone. This appearance of twisting is given
to the humerus by the direction of the musculo-spiral groove, and by the obliquity
in the direction of all the ridges of the bone. In the femur the twisted appearance
is very slight, and is most obvious below and in front of the small trochanter. In
the humerus the appearance of twisting is much more marked, and is more especially
obvious at the spiral groove. If, while the forearm remains unmoved, the lower end of
the humerus were turned outwards a quarter of a circle, so as to undo the twist of the
bone, the inner condyle would then overhang the flexor aspect of the forearm, and the
outer condyle the extensor aspect, and the flexor and extensor muscles would pass
directly downwards from the condyles to their terminations. Assuming this mode of
viewing the position of the humerus to be correct, we may proceed to compare the limbs
by considering the hand and foot, and also the forearm and leg, as having their flexor
surfaces directed towards the mesial plane of the body (the position in which they
are developed), while the condyles of the humerus and femur continue to be external
and internal in position, and the anterior or flexor surface of the humerus corresponds
with the anterior or extensor surface of the femur. From this it follows that one of
the propositions maintained by those who regard the tibia and ulna as homologous,
viz., that the quadriceps extensor femoris obviously corresponds with the triceps
brachialis, must be erroneous, and that the biceps femoris may more justly be viewed
as corresponding with the triceps brachialis, while the rectus femoris is homologous
with the biceps of the arm, and the vasti and crureus with the brachialis anticus
muscle, which in some animals extends up to the neck of the humerus ; so also the
space between the lips of the linea aspera of the femur (which in most animals is
much broader than in man) will correspond with th posterior surface of the humerus
below the musculo-spiral groove.
The detailed comparison of the bones of the shoulder and pelvis is beset with
many difficulties, and it must therefore suffice here to remark that it requires further
investigation than has been brought to bear upon it, and simply to state that while
the scapula obviously corresponds with the ilium, the clavicle is generally regarded
as corresponding with the os pubis, and the coracoid process (or coracoid bone of
birds and reptiles) with the ischium. Humphry, indeed, has put forward the idea
THE SKELETON ADAPTED TO THE ERECT POSTURE. 117
that the upper and lower limbs ought to be regarded not as lying in series but as
facing one another, that is to say, as being related to one another symmetrically,
one at the upper and the other at the lower end of the trunk, in the same way that
the limbs of the opposite sides are arranged symmetrically on each side of the mesial
plane. Thus, in the skeleton of a quadruped, the scapula and humerus slope back-
wards from the shoulder-joint, and the ilium and femur slope forwards from the hip-
joint; the prominence of the elbow looks backwards, and that of the knee looks
forwards ; and hence, according to Humphry, the coracoid and pubis and the clavicle
and ischium respectively correspond. It will, however, suggest itself to the reader
from the remarks already made, that there are serious difficulties in the way of
attributing to those appearances, which are only the result of later development,
more than a mere secondary importance. (Copious reference to the literature of this
subject is made in the paper by Ch. Martins in the " Annales des Sciences Naturelles,
Zoologie," vol. viii. 1857, p. 45. See also Humphry, " On the Limbs of Vertebrate
Animals," &c. Cambridge, 1860.)
RELATION OP THE LIMBS TO THE SEGMENTS OF THE TRUNK.
The various anatomists who have written on this subject agree in considering that
the limbs, in their extent beyond the shoulder and hip, are radiations from or appen-
dages of one or more segments of the trunk. Opinions, however, are much divided
with regard to the nature of the pelvic and shoulder girdles, and, in particular, it
has been warmly debated whether or not they are costal arches. Owen hoids the
opinion that they are costal, and further considers that the scapula and coracoid process
form the costal arch of the occipital vertebra, with the free part of the limb as its
appendage, while the clavicle is derived from another segment ; and that in like
manner the ilium and ischium form the costal arch of one segment supporting the
lower limb, and that the pubic bone belongs to another. The circumstance which has
specially led to the supposition that the upper limb and the occipital bone are con-
nected is, that the shoulder girdle is attached to the skull in most osseous fishes ; but
it may be objected to this hypothesis that in the higher vertebrata the anterior
extremities are developed from a portion of the embyro considerably removed from
the skull ; and Goodsir fairly argues, from the nervous supply to the limbs, and from
the limbs first appearing with the digits arranged in series in the plane of the lateral
plates of the embryo, that a limb is not an appendage to a single segment of the
trunk, but belongs to several segments. (Owen, " On the Nature of Limbs ; "
Goodsir, " On the Morphological Constitution of Limbs," Edinb. New. Phil. Journ.,
Jan., 1857.)
THE SKELETON ADAPTED TO THE ERECT POSTURE.
Throughout the whole of the human frame numerous peculiarities in the form and
proportion of parts exists, connected with the assumption of the erect posture. The
most striking of the structural peculiarities related to this circumstance are seen in
the skeleton, and they are equally apparent in the head, trunk, and limbs. The body
of man, unlike that of animals, is, for the purposes of station and progression, balanced
on one or both pelvic limbs, which are extended to a straight line at the knee-joint.
The lower limb is remarkable for its length and strength. The foot of man alone has an
arched instep, and it likewise presents a great breadth of sole. The great toe is distin-
guished by its large development, and, especially from that of the quadrumana, by its
want of opposability, being formed not for grasping but for supporting the weight of
the body and giving spring to the step. The femur is greatly elongated, its length
exceeding considerably that of the tibia. This length of femur is not only requisite
in order to give a sufficient extent of stride, but also to enable the body to be
balanced in different degrees and varieties of stooping. Thus, for example, in a
crouching attitude, with the feet placed side by side, it is necessary in order to
balance the fore part of the body that the pelvis should be brought back behind the
perpendicular rising from the balls of the toes on which the weight is rested : and
in order to accomplish this, if there be a long tibia directed forwards from the ankle,
there must be a femur of still greater length directed backwards from the knee. The
breadth of the pelvis, in like manner, in lateral movements of the body, enables the
balance to be more easily maintained by compensating inclinations of different parts to
118 ARTIIROLOGY.
opposite sides of the base of support, and the long neck of the femur gives an advan-
tageous insertion to the muscles by which the balance of the body on the thigh is prin-
cipally preserved (viz., the adductor and gluteal muscles), placing them more nearly at
right angles to the bones on which they act. The os innominatum is principally dis-
tinguished from the same bone in animals by the breadth of the iliac portion, which
gives support to the viscera and attachment to -the greatly developed gluteal muscles,
by the shortness and strength of the pillar of bone extending from the auricular
surface to the acetabulum, and by the marked nature of the angle which the pubic
part forms with the iliac, as it passes inwards from the acetabulum to the symphysis,
and thus completes the peculiarly broad pelvis. The strong and expanded sacrum
supports the spinal column, while the short coccyx is bent forwards and aids in
forming the floor of the pelvic cavity. The spinal column, by its pyramidal form,
is fitted to sustain the weight which bears down upon its lower part, and by means
of its different curvatures gives elasticity and strength, and allows considerable
range of motion to the trunk without removal of the centre of gravity from within
its base. The thorax is so formed as to bring the weight of its contents very much
over and to the sides of the bodies of the vertebrae rather than in front. Thus,
the thorax is broad from side to side, and compressed from before backwards ; the
transverse processes and proximal parts of the ribs are inclined backwards, so as
to enlarge the chest behind the transverse plane of the bodies of the vertebrae,
and the axis of the cavity is directed upwards and backwards, so that its contents
may thus be supported on the column in the erect posture. The upper limbs are
also thrown outwards and backwards by the long clavicles which support them
and form the fulcra of their free movements. The blades of the scapulae are
thus made to lie more nearly in one transverse plane, with the glenoid fossae looking
outwards, a position manifestly unsuited to the support of the weight of the body on
the limb. In those animals which habitually use their fore limbs for support, the
glenoid fossae look downwards, and rest on the humeri ; but if the human body be
placed so as to be rested on the hands, the glenoid cavity lies on the inside of the
head of the humerus, and the scapula is supported upon the humerus by the acromion
process. While stability and strength have been provided in the lower limb, mobility*
and lightness have been secured in the upper. This is apparent on comparison of
the shoulder, elbow, and wrist, with the hip, knee, and ankle. In the hand also,
the movable phalanges are as long as the carpal and metacarpal bones taken together,
whereas in the foot they are not a third of the length of the tarsal and metatarsal
bones. The skull of man differs from that of animals in being nearly balanced on
the vertebral column, the condyles of the occipital bone being brought forwards
towards the middle of the base, by the comparative shortness of that part of the skull
which lies in front of the foramen magnum, and the projection backwards of that
which lies behind it. In animals the skull hangs forwards, as it were, from the
extremity of the column, and is sustained by an elastic substance (ligamentum
nuchae), which is attached on, the one hand to the spinous processes of the vertebrae,
and on the other to the occipital protuberance.
SECTION II. ARTHROLOGY.
MODES OP ARTICULATION.
THE name of articulation, synonymous with joint, is given in descriptive
anatomy to the connection subsisting in the recent skeleton between any of
its denser component parts, whether bones or cartilages. In all instances,
excepting the bones of the head, which are so closely set together in the
sutures as to have no more than the fibrous periosteum between them,
some softer intervening substance lies between the bones, uniting them
together, or clothing the surfaces which are opposed ; but the manner
in which the several pieces of the skeleton are thus connected, or the
modes of articulation, vary to a great degree both in the form and nature
of the uniting substances, and in the extent of motion which they allow
ARTICULATIONS IN GENERAL. 119
between the bones. In some instances, as in that of the cranial bones
already referred to, the closeness of the apposition, the unevenness of the
fitting surfaces or edges, and the small amount and dense nature of the
intervening substance, are such as to admit of little or no perceptible
motion. In other instances the extremities of the bones are placed at such
a distance, and the intervening substance (ligament or cartilage) possesses so
much of a yielding quality, that bending or other motions may take place,
even while the bones are thus mediately but continuously united. But in
the greater number of the connections between the bones, and in those
which may be regarded as more properly deserving the name of joints, the
apposed surfaces of bone are not united either directly or mediately with
each other, but are free by solution of continuity, and are covered with
plates of smooth cartilage, the surfaces of which fit accurately together,
and the bones are held together by ligamentous structures placed in the
vicinity of the joints. In such articulations the bones are capable of gliding
or moving upon each other in various extent and directions, according to
the shape of the opposed cartilaginous surfaces, and the form and attach-
ments of the ligamentous and other bands which unite them. It is upon
distinctions such as those now adverted to that the various kinds of joints or
articulations have been brought under the three classes of SYNARTHROSIS,
AMPHIARTHROSIS, and DIARTHROSIS.
Synarthrosis means direct or immediate union, and comprehends the
joints with little or no motion. It is found chiefly in various forms of
suture by which the bones of the head, excepting the lower jaw, are
united. The suture, properly so called, is serrated or dentated when the
contiguous margins of the bones are subdivided or broken up into projecting
points and recesses by which they fit very closely to one another, as in the
borders of most of the tabular bones of the cranium. The squamous or scaly
suture is that in which, as in the union of the temporal with the parietal
bone, the edges are thinned and bevelled, so that one overlaps the other
to a considerable extent.
The term harmonia has been employed to denote simple apposition of compara-
tively smooth surfaces or edges, as in the case of the two superior maxillary bones;
and the term schindylesis has been used to express that kind of union in which one
bone is received into a groove in another, as occurs between the rostrum of the
spheuoid bone and the vomer. The impaction of the roots of the teeth in their
sockets has likewise been reckoned among the articulations, though with doubtful
propriety, and has been designated by the term gomphosis.
Amphiarthrosis means the mixed articulation, or that in which there is
mediate union by some intervening substance, with partial mobility. The
articulations between the bodies of the vertebrae, that between the two ossa
pubis at the symphysis, and that between the two first pieces of the sternum,
may be taken as examples of this mode of connection. Some of the joints
of this kind pass on the one hand into synarthrosis, and on the other into
diarthrosis.
Diarthrosis includes the complete joints with separate surfaces of the bones
and synovial cavities, and is attended with considerable yet varying degrees
of mobility. In this form of joint, plates of cartilage cover the articular parts
of the bones and present within the joint free surfaces of remarkable smooth-
ness, and these surfaces are further lubricated by the syuovial fluid secreted
from the delicate membrane which lines the fibrous coverings and all other
parts of the articulating cavity except the cartilage. This membrane is con-
tinuous with the margin of the articular cartilages, and along with the
120 ARTICULATIONS IN GENERAL.
cartilages completely encloses the joint cavity. The bones are further held
together by fibrous tissue in the various forms of ligaments, such as mem-
branous capsules, flat bauds, or rounded cords. These ligaments, it is true,
are not so tight as to maintain the bones in close contact in all positions of
the joint, but are rather tightened in some positions arid relaxed in others,
so that they may be looked upon chiefly as controllers of the motions. The
bones are likewise held together in diarthrodial joints, by atmospheric
pressure, and by the surrounding muscles.
MOTIONS OF THE BONES IN THE JOINTS.
The various movements of the bones on one another in the joints are dis-
tinguished by different terms according to their directions, viz., angular
movement, circumduction, rotation, and shifting ; but it is proper to remark
that although different kinds of motion, answering to these several terms,
may readily be recognised, yet there are few of the motions which occur in
the joints which are of one sort only, but rather several kinds of movement
are frequently combined in one, and they also run into one another in great
variety.
Angular movement, or opposition, is movement in such a manner as to
increase or diminish the angle between two bones, so that they shall lie more
or less nearly in a straight line. The different kinds of angular movement
are designated by different terms according to the directions in which they
take place with reference to the limb or body : thus, flexion and extension
indicate angular movements, which have the effect of bending or straightening
parts upon one another or upon the trunk of the body : adduction and abduc-
tion indicate angular movement to and from the mesial plane of the body,
or, when fingers and toes are referred to, these terms may be used to denote
movement to and from the middle line of the hand or foot.
Circumduction is the movement performed when the shaft of a long bone
or a part of a limb describes a cone, the apex of which is placed in the joint
at or near one extremity of the bone, while the sides and base of the cone
are described by the rest of the moving part.
Rotation signifies movement of a bone round its axis without any great
change of situation.
Shifting is a term which may be applied to that kind of movement in
which the surfaces of adjacent bones are displaced without any accompanying
angular or rotatory motion, as in the sliding of flat surfaces over each
other, such as in some of the carpal and tarsal articulations, or in the move-
ment of advance and retreat of the lower jaw.
The term ginglymus is used to distinguish a hinge joint, or one which admits only
of flexion and extension. Enarihrosis (Cruveilhier) is the ball-and-socket form of
joint, like the shoulder and hip, allowing motion in every direction. Artkrodia
is employed by Winslow and Cruveilhier to signify a joint admitting of very little
movement.
In the preceding paragraphs attention has been called only to the directions of the
movements of the parts united in the joints, but the movements of opposed articular
surfaces relatively one to another are likewise worthy of notice.
In the movements of the joints, when occurring between separate opposed
surfaces, there is generally more or less of a gliding motion of one surface on the
other ; but it is to be observed that in some joints a small amount of motion may be
produced without gliding, by the alternate contact and separation of different parts
of the opposed surfaces, to which the name of coaptation (Goodsir) has been applied ;
and that in other joints the articular surface of one bone may travel over that of
another, so as to bring different parts of the surfaces successively into contact, in the
ARTICULATIONS OF THE VERTEBRAL COLUMN.
121
manner of a wheel rolling on the ground, with or without this change of place being
accompanied by gliding motion.
In the various joints provided with synovial cavities, the cartilaginous surface of
the bones are so formed as usually to be in close apposition or contact ; but it would
appear that in certain positions they are not entirely so, and it can scarcely be
doubted that when the surfaces are separated to any extent, doubling of the synovial
membrane, or fatty processes connected with it and placed in the immediate
vicinity of the joint, contribute to fill up the vacuity. There are even instances in
which it would appear that the separation of the surfaces must be considerable, as in
the case of the patella, more especially in complete extension of the knee.
ARTICULATIONS OF THE TRUNK AND HEAD.
ARTICULATIONS OF THE VERTEBRAL COLUMN.
The movable vertebrae are connected together by elastic discs interposed
between the bodies ; by synoviul joints between the articulating processes ;
and by ligaments.
Fig. 107. A LUMBAR VERTEBRA, SEEN FROM
ABOVE, WITH PART OF THE INTERVERTEBRAL
DlSC ADHERING TO THE BODY. A
1, 1, the concentric arrangement of the fibrous
laminae ; 2, the central soft cartilaginous or
gelatinous substance.
The intervertebral discs are plates of
composite structure placed one between
the bodies of each pair of vertebrae from
the axis to the base of the sacrum. Each
is composed of a laminar part externally,
and of a pulpy substance in the centre.
The laminar part forms more than
half of the mass, and consists of con-
centric laminae of fibre-car tilage and fibrous tissue alternating one with
another. These laminse are not quite vertical, for if a vertical section of a
disc be made, a certain number of the layers nearest to the circumference of
the disc will be seen bulging outwards, while others situated more deeply
and less closely compacted together are convex towards the centre ; and
Fig. 108.
Fig. 108. VERTICAL ANTERO-
POSTKRIOR SECTION THROUGH
TWO LUMBAR VERTEBRAE, SHOW-
ING THE ARRANGEMENT OF THE
INTERVERTEBRAL Disc.
1, 1, the fibrous oblique bauds,
which are curved outwards; 2,
those which are curved inwards;
3, the central soft cartilaginous or
gelatinous substance : the capsule
of the joint between the articular
processes is represented.
when the spine is bent in
any direction, the curves of
the different layers are aug-
mented on the side towards which the column is inclined. The in-
dividual layers consist chiefly of fibres extending obliquely between the
122 ARTICULATIONS OF THE TRUNK AND HEAD.
vertebrae and firmly attached to both ; the direction of the obliquity being
reversed in each successive layer, in one stretching downwards from right to
left, and in the next from left to right. Some of the fibres also are nearly
horizontal. The central part of the fibro-cartilage is a pulpy and elastic
material which, when the pressure which confines it is taken off by cutting
through the intervertebral substance, rises up so as to assume a conical form.
It is then seen to be of a lobate structure, and, examined under the micro-
scope, exhibits a finely fibrous and homogeneous matrix, with numerous
spherical and elliptical cells, some of them resembling cartilage corpuscles,
others larger and of various appearance.
It is now generally admitted that the pulp of the intervertebral disc is a persistent
part of the chorda dorsalis ; homologous, therefore, with those larger vestiges of the
chorda dorsalis which occupy the biconical cavities between the bodies of the vertebrae
in fishes. According to Luschka, there is present in each disc a synovial cavity, and
the lobes of the pulp are synovial villi, similar to those which are to be found in the
knee and shoulder joints, but of larger size, and occupying the whole cavity; and it
is worthy of notice that in like manner secondary cavities, developed within the
chorda dorsalis, are found in the intervertebral substance in many fishes. The same
writer describes small synovial sacs, in the cervical region, in those parts of the discs
which are attached to the lateral elevations of the bodies of the vertebrae. Occasionally
the pulp of the discs projects backwards, through the surrounding laminae, so as to
form a slight projection into the spinal canal. (Luschka, "Die Halbgelenke des
Menschlichen Korpers," Berlin, 1858, p. 84.)
A thin cartilaginous layer, incomplete towards the circumference, covers
the surfaces of the vertebrae and gives attachment to the discs. Ex-
cluding from consideration the first two vertebras, between which it does not
exist, the intervertebral material forms in length about a fourth of the movable
part of the column. The dorsal part of the column has, comparatively with
the length, a much smaller proportion than the cervical or lumbar parts.
The discs in the cervical and lumbar regions are thicker in front than behind, and
it has been determined that the convexity of those portions of the column is due to
them much more than to the bodies of the vertebrae, while the arching of the dorsal
portion, on the contrary, is rather owing to the shape of the bones. (W. and E.
Weber, " Mechanik der menschl. Gehwerkzeuge," p. 90, et seq., Gottingen, 1836.)
The anterior common ligament is a strong band of fibres, which is placed
on the front of the bodies of the vertebrae, and reaches from the atlas to the
first bone of the sacrum, becoming broader as it descends. It consists of
longitudinal fibres which are dense, firm, and well marked. The superficial
fibres extend from a given vertebras to the fourth or fifth below it ; the fibres
subjacent to these pass over the bodies of several vertebrae ; whilst the
deeper ones pass only between adjacent vertebras. The band is thicker
towards the middle of the bodies of the vertebrae than at their margins, or
over the intervertebral cartilages ; by which means the transverse depressions
of the bodies are filled up, and the surface of the column rendered more
even. The fibres adhere more closely to the margins of the bones than to
the middle of their bodies, and still more closely to the in vertebral carti-
lages. Upon the sides of the bodies there are some fibres which are thin
and scattered, and reach from one bone to another.
The posterior common ligament is situated within the spinal canal, and is
attached to the posterior surface of the bodies of the vertebras ; it extends
from the occiput to the sacrum. It is smooth, shining, and broader at the
ARTICULATIONS OF THE VERTEBR2E.
123
upper than at the lower part of the spine. In the neck it extends quite
across the bodies, but in the back and loins it is broader opposite the inter-
Fig. 109. VlEW OP A PART OP THE
VERTEBRAL COLUMN, INCLUDING THE
5m, 6iH, TTH, STH, AND QTH
DORSAL VERTEBRAE, WITH A PART
OP THB 6TH, ?TH, AND 8lH RlBS,
FROM THE RIGHT SIDE AND FRONT. ^
The 5th and 9th ribs have been
removed so as to show the articular
surfaces of the vertebrae corresponding
to them ; 1 to 2, the anterior common
ligament of the bodies of the vertebrae ;
at x x , a portion of the ligament is
removed so as to expose the inter-
vertebral plate between the 8th and
9th vertebrae, in which the diagonal
fibres of the external ligamentous
plates are represented. (The further
description of this figure will be found
at p. 129.)
vertebral cartilages than at the
middle bodies, so that its mar-
gins present a series of points
or dentations with intervening
concave spaces. It adheres firmly
to the fibro-cartilages and to the
contiguous margins of the bodies
of the vertebrae, but it is sepa-
rated from the middle of the
bodies by the transverse parts of the large venous plexus, which is in con-
tact with the bones. Between the ligament and the prolongation of the dura
mater which lines the canal, some loose connective tissue is interposed.
Fig. 110.
Fig. 110. THE BODIES OP THREE LUMBAR VERTEBRA, SEEN FROM
BEHIND, WITH THE POSTERIOR COMMON LlGAMENT. ^
The arches have been removed by cutting through the pedicles.
The contraction of the posterior common ligament opposite the
middle of each body, and its greater width and attachments opposite
the intervertebral discs, are represented.
The joints of the articulating processes present each a
synovial cavity surrounded by an irregular fibrous capsule.
The fibrous bands of these capsules are longer and looser
in the cervical than in the dorsal and lumbar regions.
The liyamenta subflava are ligaments consisting of
yellow elastic tissue, which connect the laminae of the
vertebrae. Their fibres are nearly vertical, and are at-
tached superiorly to the anterior surface of the lamina, a little above the
inferior margin, and inferiorly to the upper margin and part of the posterior
surface of the lamina beneath. They are most distinctly seen when the
arches are detached from the bodies of the vertebrae, and they are viewed
from the front. Posteriorly they appear short, or in the dorsal region are
concealed, being overlaid by the prominent inferior margins of the laminae
124
ARTICULATIONS OF THE TRUNK AND HEAD.
Fig. 112.
and the roots of the spines. Their outer margins are close to the articu-
lating processes ; their inner margins lie in contact in the middle line, and
in that situation the ligaments are thickest.
Fig. 111. Fig. 111. THE ARCHES OP THREE DORSAL VER-
TEBRA, SEEN FROM BEFORE, TO SHOW TEE LlGA-
MENTA SUBFLAVA. ^
The bodies of the vertebrae have been removed by
sawing through the pedicles, showing the articular
capsules and the ligamenta subflava.
The ligamenta subflava do not exist be-
tween the occiput and the atlas, nor between
the latter and the axis ; common fibrous
membrane supplies their place in these two
spaces, constituting posterior occipito-atlautal
and atlanto-axial ligaments.
The interspinaus ligaments, thin and
rather membranous, have an attachment
extending from the root to near the
summit of each spinous process, and
connect the inferior border of one with
the superior border of that next below
it. They are best seen in the lumbar
region, and are least developed in the
neck.
The supraspinous ligaments consist of
small compressed bundles of longitudinal
fibres, which connect the summits of the
iFig. 112. ANTERO-POSTERIOR VERTICAL SEC-
TION OF THE UPPER PART OF THE VERTEBRAL
COLUMN, AND PART OF THE OCCIPITAL BONE,
SHOWING THE ARTICULATIONS (after Arnold).
1, 1, anterior common ligament of the bodies
of the vertebrae ; 1', anterior atlanto-occipital
ligament ; 2, from this figure upwards the pos-
terior common ligament of the bodies ; 2', the
continuation of the preceding and the apparatus
ligamentosus lying on the basilar process of
the occipital bone ; 3, 3, 3, these figures are
placed on the inside of the arches of the 2nd
and 7th cervical and 6th dorsal vertebrae ; the
ligamenta subflava are to be seen stretching
between the laminae ; 4, 4, placed upon two of
,the interspinous ligaments ; 4', divided edge of
the occipital bone behind the foramen magnum,
and below it, the posterior occipito-atlautal
ligament and ligaments of the arches; 5, 5,
supraspinous ligaments ; 6, ligamentum nuchae ;
x , its upper extremity at the occipital tube-
rosity ; x x , its lower extremity terminating
in the supraspinous ligaments of the upper
dorsal vertebrae.
spinous processes, and form a continuous
chain from the seventh cervical vertebra to the spine of the sacrum. The
posterior fibres pass down from a given vertebra to the third or fourth
ARTICULATIONS OF THE VERTEBRA. 125
below it ; those more deeply seated reach only from one to the next, or the
second below it.
The ligamentum nuchce is the continuation upwards of the supraspinous
ligament. It is, in the human subject, a thin intermuscular septum of
elastic and white fibrous tissue, the most superficial part of which extends
from the spine of the seventh cervical vertebra to the occipital protuberance,
while the deeper fibres, springing from the same origin, pass to the occipital
spine, and the spines of the six upper vertebrae. It derives importance as
the representative of a strong elastic structure in other animals.
The intertransverse ligaments are unimportant bands extending between
the transverse processes. In the lumbar region they are membranous, in the
dorsal region they are rounded bundles intimately connected with the
muscles of the back ; and in the neck they are usually reduced to a few-
irregular fibres, which may in some instances be wanting.
MOVEMENTS. The movement of flexion and extension of the vertebral column is
freely allowed in the cervical and lumbar regions, but in the dorsal is limited by the
small amount of intervertebral substance and the imbrication of the laminae. The
greatest bending backwards is permitted in the cervical, the greatest bending
forwards in the lumbar region, especially between the fourth and fifth lumbar
vertebrae. Movements in other directions are limited chiefly by the articulating
processes. In the dorsal region the articulating surfaces of each vertebra lie in the arc
of a circle whose centre is in front of the vertebra, and round tnis centre a consider-
able degree of rotation is permitted. In the lumbar region, the centre of the circle
in which the articular surfaces lie being placed behind, rotation would involve an
amount of motion between the bodies of the vertebrae that is impossible ; the articu-
lating processes, however, fit sufficiently loosely to permit of lateral flexion, and by
combination of this with antero-posterior flexion, some degree of circumduction is
produced. The articulating surfaces of the cervical vertebrae, being oblique and
placed in nearly the same transverse plane, allow neither pure rotation nor pure
lateral flexion. They permit, besides forward and backward motion, only one other,
which is rotatory round an oblique axis the inferior articulating process of one side
gliding upwards and forwards on the opposing surface, and that of the other side
gliding downwards and backwards, by which a combination of lateral flexion and
rotation is obtained. The reader who may wish to pursue more minutely the study
of the movements of the joints may consult the work of W. and E. Weber already
cited ; H. Meyer, "Handbuck der Physiol. Auat. ;"and Henke, "Handbuch der Anat.
und Mech. der Gelenke/' 1864.
ARTICULATIONS OF THE ATLAS, AXIS, AND OCCIPITAL BONE.
The atlas, axis, and occipital bone are connected by articular surfaces and
ligaments, without the presence of intervertebral discs.
Two pairs of synovial articulations surrounded by capsular ligaments
connect the lateral masses of the atlas with the superior articular surfaces
of the axis and with the condyles of the occipital bone. The capsule of the
atlanto-axial joint is strengthened behind by an accessory ligament, directed
downwards and inwards to the body of the axis near the base of the
odontoid process.
The transverse ligament of the atlas is a strong and thick band, which
extends across the ring of the atlas, and retains the odontoid process in its
place. It is attached on each side to the impression below the inner border
of the superior articulating process. It is arched backwards behind the
odontoid process, and is broadened out in the middle line. From the
middle of its posterior surface a short thin bundle of fibres passes down to
be attached to tho body of the axis, whilst another passes up to the basilar
126
ARTICULATIONS OF THE TRUNK AXD HEAD.
process. These form the figure of a cross with the transverse ligament,
and serve to bind the occiput to the first two vertebrae ; from this arrange-
ment is derived the term cruciform, which is sometimes applied to the
transverse ligament and its appendages together.
Fig. 113. TRANSVERSE VER-
TICAL SECTION OP THE
LOWER PART OF THE Oc-
CIPITAL BONE, AND THE
TWO UPPER VERTEBRA
BEHIND THE ARTICULA-
TIONS (after Arnold). ^
1, 1, apparatus ligaraen-
tosus and posterior common
ligament of the bodies of the
vertebrae dissected off the
back of the odontoid process,
and turned up on the occi-
pital bone; 2, 2', vertical
part, and 3, 3, transverse
or principal part of the cru-
cial ligament ; x , neck of
the odontoid process ; 4, 4, the alar, lateral, check, or occipito-odontoid ligaments ;
5, 5, the accessory ligaments of the atlanto-axial capsules, or the lower lateral ligaments
of the odontoid process ; 6, 6, part of the capsular ligaments of the condyloid articula-
tions ; 7, 7, capsular ligaments of the atlanto-axial articulations ; 8, 8, intertransverse
ligaments between the occiput and atlas.
Two synovial membranes are placed one in front and another behind the
odontoid process ; the first of these is situated between the process and the
anterior arch of the atlas, the other between the process and the transverse
ligament.
icjg 114 Fig. 114. VIEW OF THE ARTICULATION OF
THE ODONTOID PROCESS OF THE Axis WITH
THE ATLAS, THE UPPER PART OF THE AN-
TERIOR ARCH OF THE ATLAS AND THE HEAD
OF THE ODONTOID PROCESS HAVING BEEN
REMOVED BY A HORIZONTAL SECTION.
1, cut surface of the odontoid process ; 2,
cut surface of the anterior arch of the atlas ;
3, transverse ligament ; between 1 and 2, the
anterior synovial cavity ; between 1 and 3, the
posterior synovial cavity of the articulation ;
at the sides of the odontoid process, between
the anterior and posterior synovial sacs, are
seen loose ligamentous fibres ; 4, is placed on
the back part of the left superior articular process of the atlas : the anterior part of
this process, and that of the other side, have been partly removed by the section.
For the sake of distinctness, the synovial spaces are represented somewhat wider than
natural.
The odontoid or check ligaments are two thick and very strong bundles of
fibres, which extend from the sides of the summit of the odontoid process
outwards and a little upwards to be implanted into the rough depression on
the inner side of the condyles of the occipital bone, and into a small part of
the margin of the foramen magnum. Some of the fibres of the two liga-
ments are continuous across the middle line.
ARTICULATIONS OF THE ATLAS AND AXIS.
127
Fig. 115. TRANSVERSE SECTION SIMILAR TO
THAT REPRESENTED IN FlG. 113, WITH A
SMALLER PORTION OF THE OCCIPITAL BONE,
THE CRUCIAL LIGAMENTS BEING REMOVED.
4, alar or odontoid ligament ; 5, accessory
atlanto-axial ligament ; 6, 7, capsular liga-
ments of the occipito-atlantal and the atlanto-
axial articulations ; 9, placed on the head of
the odontoid process; 9, 9', superior or median
occipito-odontoid ligament.
The ligamentum suspensorium dentis
or middle odontoid ligament consists of
fibres which pass directly upwards from
the summit of the odontoid process to
the margin of the foramen magnum.
Fig. 115.
Fig. 11 6.
Fig. 116. THE LIGAMENTOUS STRUCTURES WHICH SURROUND THE ARTICULATIONS OP
THE OCCIPUT AND TWO UPPER VERTEBRAE.
A, the lower part of the skull sawn transversely through the basilar process, with the
atlas and axis, viewed from before. 1, the anterior occipito-atlantal ligament; 2, the
middle thickened part or accessory occipito-atlantal ligament ; 3, the anterior atlanto-
axial ligament.
B, the lower part of the skull, with three adjacent vertebra, viewed from behind. 1,
the posterior occipito-atlantal ligament ; 2, the posterior atlanto-axial ligament.
C, the occipital bone sawn transversely through the foramen magnum, and a part of the
arches of the atlas and axis removed posteriorly, so as to show the thickened prolonga-
tion of the posterior common ligament of the bodies of the vertebra with the apparatus
ligamentosus.
128 ARTICULATIONS OF THE TRUNK AND HEAD.
The occipito-axial ligament, sometimes called apparatus ligamentosus, is
placed beneath the upper part of the posterior common ligament, and covers
the crucial and odontoid ligaments. It is a broad band attached above in
the basilar groove, and below to the body of the axis.
The anterior occipito-atlantal ligament extends from the anterior border
of the occipital foramen, between the condyles, to the margin of the anterior
arch of the atlas. It is thin, broad, and membranous ; but in the median
line it is strengthened by an accessory ligament, thick and round, placed in
front of it, which is sometimes described as the commencement of the
anterior common ligament.
The anterior atlanto-axial ligament, likewise thin and membranous, except
in the middle, where it is thickened, extends from the border of the anterior
arch of the atlas to the body of the axis.
The posterior occipital- atlantal ligament, thin and membranous, is attached
superiorly to all that part of the margin of the occipital foramen which is
behind the condyles, and inferiorly to the adjacent border of the arch of
the atlas. It is partly blended with the- dura mater.
The posterior atlanto-axial ligament, similar to the preceding, connects the
neural arch of the atlas with that of the axis, in the absence of ligamentum
subflavum.
MOVEMENTS. The atlanto-axial articulation is so constructed that the head, toge-
ther with the atlas, is rotated on the axis ; the odontoid process serving as a pivot. The
rotation is limited by the check ligaments. The atlanto-occipital articulation takes no
part in rotation, but allows the head to be freely raised or depressed upon the vertebral
column. When the atlas is placed symmetrically over the axis, it is seen that the
opposing articular surfaces, instead of fitting one to the other, come very slightly into
contact, the surface of the axis being inclined too little outwards, and presenting an
antero-posterior convexity, to which there is no corresponding concavity presented by
the atlas ; but a slight rotation brings the bones into a stable position, in which the
anterior half of one articular surface of the axis and the posterior half of the other are
laid closely against the atlas. It will also be found that a certain amount of oblique
motion between the atlas and occipital bone is permitted, by which the anterior half
of one condyle and the posterior part of the other may be rested together on the atlas,
and that that is the position of greatest stability. This oblique position is that into
which the bones are brought when there is any lateral curving of the column, as is
the case in the most natural and easy attitudes.
ARTICULATIONS OF THE RIBS.
The articulations of the ribs may be divided into three sets, connecting
them with the bodies of the vertebrae, with the transverse processes, and
with the sternum.
The costo-mrtebral articulation unites the head of the rib, in most instances,
with the bodies of two vertebrae by two distinct synovial joints, supported
by ligaments as follows.
The anterior costo-vertebral , costo- central, or stellate ligament is divided
into three bundles, of which the middle one passes horizontally forwards
upon the corresponding intervertebral fibro-cartilage, whilst the superior
ascends to the body of the vertebra above it, and the inferior descends to
that below. In the first, eleventh, and twelfth ribs, this ligament is inserted
into only one vertebral body, and into no fibro-cartilage.
The interarticular ligament is a thin and short band of fibres, which
passes transversely from the ridge separating the two articular surfaces on
ARTICULATIONS OF THE RIBS.
129
the head of the rib to the intervertebral substance, and divides the articu-
lation into two parts, each lined by a separate synovial membrane. The
Fig. 117. VIEW OF A PART OF THE Fig. 117.
VERTEBRAL COLUMN, INCLUDING THE
5iH, GTH, 7iH, STH, AND 9iH
DORSAL VERTEBRA, WITH A PART
OF THE 6TH, 7TH, AND 8lH
RlBS, FROM THE RIGHT SIDE AND
FRONT. ^
The 5th and 9th ribs have been
removed so as to show the articular
surfaces of the vertebrae corresponding
to them ; 1 to 2, the anterior common
ligament of the bodies of the vertebrae ;
at x x , a portion of the ligament is
removed, so as to expose the inter-
vertebral plate between the 8th and
9th vertebrae, in which the diagonal
fibres of the outermost ligamentous
plates are represented ; 3 and 4, the
heads of the 6th and 7th ribs, from
which the stellate or anterior costo-
central ligaments are seen spreading
over the two adjacent vertebral bodies
and intervertebral substance ; 5, the
head of the eighth rib, from which the
stellate ligament has been removed, so
as to expose the upper and lower
synovial cavities, and between them
the intervertebral or deep costo-central
ligament ; 6, lower, and 6', upper
facet of the costo-central articulation ;
7, posterior costo-transverse ligament ;
7', the costo-transverse synovial cavity ; 7", the costo-transverse articular facet of the
5th vertebra; 8, the anterior or superior costo-transverse ligament; 9, superior articular
process of the 5th vertebra ; 9', inferior of the 9th.
ligament does not exist in the articulations of the first, eleventh, or twelfth
ribs, in consequence of those ribs being each attached to only one vertebral
body by a single synovial joint.
Fig. 118. FIVE DORSAL VERTEBRAE, WITH PORTIONS
OF THE CORRESPONDING RlBS. J
1 and 2 are placed on the laminae of the vertebrae,
close to the interspinous ligaments ; 3, one of the
ligamenta subflava, which are only in part seen, being
covered to some extent by the laminae of the vertebrae ;
4, anterior costo-transverse ligament ; 5, posterior
costo-transverse ligament.
The COSTO-TRANSVERSE ARTICULATION Unites
the tubercle and neck of the rib to the cor-
responding transverse process by a synovial
joint and ligaments, and by a longer ligament
to the transverse process above.
The posterior costo-transverse ligament is a distinct band extending out-
wards from the posterior part of the summit of the transverse process to the
rough external part of the tubercle of the rib.
130 ARTICULATIONS OF THE TRUNK AND HEAD.
The middle or interosseous costo-transverse ligament, or ligamentum colli
cost<x t consists of a series of very short parallel fibres, which unite the neck
of the rib to the anterior
Fig. 119. surface of the contiguous
Fig. 119. HORIZONTAL SECTION
OP A DORSAL VERTEBRA, WITH
THE ADJACENT PORTIONS OF TWO
RIBS.
1, the rib ; 2, transverse pro-
cess ; 3, anterior costo-central liga-
ment ; 5, posterior costo-transverse
ligament ; 6, interosseous or middle
costo-transverse ligament.
transverse process. These
fibres are seen on removing
by horizontal section a por-
tion of the rib and transverse process, and forcibly drawing the one from
the other.
The anterior, superior, or long costo-transverse ligament consists of fasciculi
of fibres, passing from the neck of the rib obliquely upwards and outwards
to the lower margin of the transverse process next above it. It does not
exist in the articulation of the first rib.
There are no- synovial joints, but only posterior costo-transverse ligaments,
between the two lowest ribs and the transverse processes.
The COSTO-STERNAL AftTicuLATiONS, situated between the anterior angular
extremities of the cartilages of the sternal ribs, and the corresponding fossae
in the margins of the sternum, consist of small synovial capsules covered
and supported by anterior, posterior, upper and lower ligaments. The
anterior ligamentous fibres are thin, scattered, and radiated, passing from
the extremity of the cartilage to the anterior surface of the sternum, where
they interlace with those of the opposite side, and are blended with the
aponeurosis of the pectoralis major muscle ; the posterior fibres are similarly
disposed, but not so thick or numerous, and connect the thoracic surfaces
of the same parts ; the upper and lower ligamentous fibres are inconsider-
able, and are placed above and below the joint. The synovial membranes are
interposed between the end of the cartilage of each true rib (excepting the
first) and the sternum, and may best be demonstrated by slicing off a little
of the anterior surface of the sternum and cartilage ; that of the seventh
is single ; the others are usually divided into an upper and lower cavity, be-
tween which interarticular fibres are attached to the end of the cartilage and to
the sternum. The cartilage of the first rib is directly united to the sternum.
A thin fasciculus of fibres connecting the cartilage of the seventh rib, and
sometimes likewise that of the sixth, with the xiphoid cartilage, is called the
costo-xiphoid ligament.
Articulation of the cartilages one with another. The contiguous edges of
the cartilages of some of the ribs, viz. , from the sixth to the ninth, have
a part of their adjacent borders smoothed into articular surfaces, which are
lined by synovial membranes, and are held in connection by ligamentous
fibres. Some of the articular surfaces are occasionally found to be wanting.
Connection of the ribs with their cartilages. The external extremities of
the cartilages are fixed into the oval depressions on the ends of the ribs,
and the union receives support from the periosteum.
ARTICULATIONS OF THE RIBS AND STERNUM.
131
Fig. 120.
Fig. 120. ARTICULATIONS OP THE
STERNUM, CLAVICLE AND RIBS,
AS SEEN FROM BEFORE (after
Arnold),
On the right of the middle line
the anterior ligaments are shown ;
on the left side, the front parts of
the clavicle, sternum and costal
cartilages have been removed so as
to display the articular cavities.
1 to 10, the anterior extremities of
the ribs from the first to the tenth
inclusive, on the right side ; 1' to
10', the costal cartilages of the left
side from the first to the tenth in-
clusive ; at 1', the direct union of
the first costal cartilage with the
sternum is shown ; at the sternal
ends of the cartilages marked 2' to
6', the small double synovial cavi-
ties are shown opened ; between
the costal cartilages on the right
side, ligamentous bands are shown
stretching over the intercostal
spaces ; and on the left side, by a
section, small synovial cavities are
shown between the adjacent edges
of the intercostal cartilages from
the 5th to the 9th ; on the front
of the right half of the sternum
the radiating anterior costo-sternal
ligaments are shown ; 11, the ensi-
form process; 12, 12', the inter-
clavicular ligament; and below 12,
the anterior sterno- clavicular liga-
ment ; below 12', the sterno-clavi-
cular articulation is opened, showing
the interarticular fibro-cartilage and
double synovial cavity ; 13,thecosto-
clavicular or rhomboid ligament.
Ligaments of the sternum. The manubrium, body, and xiphoid process
of the sternum, so long as they are not united by bone, are connected
by intervening cartilage, and by anterior and posterior ligaments ; and
the whole sternum is much strengthened by thick periosteum and by
the crossing and longitudinal bauds of the costo-sternal ligaments already
mentioned.
MOVEMENTS OF THE RIBS. Each rib is capable of a certain amount of elevation
and depression at its vertebral articulation, and of rotation on an axis passing between
its vertebral and sternal ends. The heads of the ribs are, however, bound down by
the interarticular ligaments so tightly as to prevent any gliding motion at the
attachments of those ligaments, which may therefore be regarded as the fixed points
round which the ribs are moved. When the vertebral column is bent forwards, the ribs
are depressed ; and in the same manner, when the column is rotated, the ribs of that
side towards which the upper part of the trunk is turned are raised, and those of
the other side correspondingly depressed. The movement of the tubercle of the rib
on the transverse process is of a gliding description., in the circumference of a circle
of which the head of the rib is the centre ; and as the plane in which the opposed
surfaces of the costo-transverse articulation in most instances lies looks upwards and
backwards, the ribs are moved backwards as well as upwards in inspiration, and
forwards and downwards in expiration. The combined movements of the thoracic
walls in respiration will be described along with the actions of the intercostal
K.2
132
ARTICULATIONS OF THE TRUNK AND HEAD.
muscles. It is sufficient at present to state that the elevation and rotation of the
ribs in inspiration are the main causes of the antero-posterior and transverse enlarge-
ment of the chest. The angular movement is greatest in the upper and least in the
lowest ribs.
TEMPOfcO-MAXILLARY ARTICULATION.
The lower jaw articulates by its condyle on each, side with, the smooth
surface of the temporal bone, extending over the part of the glenoid fossa
Fig. 121.
Fig. 121. A PORTION OP THE
SKULL AND LOWER JAW WITH
HALF THE HYOID BONE, SEEN
FROM THE RIGHT AND OUTER
SIDE (after Arnold). ^
1, the external lateral ligament
of the temporo-maxillary articula-
tion ; 2, a part of the capsular
ligament of the joint ; 3, styloid
process; 4, stylo-maxillary liga-
ment ; 5, stylo-hyoid ligament ;
6, the lesser cornu of the hyoid
bone with some short ligaments
attaching it to the body and great
cornu ; 7, the body ; 8, the ex-
tremity of tbe great cornu.
in front of the Glaserian
fissure and the anterior root
of the zygoma. The joint is
divided by an interarticular
nbro-cartilage into an upper
and a lower synovial cavity.
The external lateral ligament is a short fasciculus of fibres, attached
Fig. 122. A PORTION OF THE SKULL
AND LOWER JAW WITH HALF THE HYOID
BONE, SEEN FROM THE INSIDE.
The indications where marked are the
same as in Fig. 121 ; the styloid process,
3, is detached from the skull ; the body of
the hyoid bone, 7, is represented as cut
through in the middle, so tbat tbe posterior
and inner surface of the right half of the
bon is seen ; 9, the internal lateral liga-
ment of the temporo-maxillary joint ; 10,
the upper opening of the inferior maxillary
canal.
above to the external surface and the
tubercle of the zygoma ; and below,
to the external surface and poste-
rior border of the neck of the
lower jaw, its fibres being directed
downwards and backwards. Thin
and short additional ligamentous
fibres cover the synovial membrane and form an irregular capsule round
the joint.
TEMPORO-MAXILLARY ARTICULATION,
1.33
The internal lateral ligament, thin, loose, and elongated, lies at some
distance from the joint. It extends from the spinous process of the
sphenoid bone downwards and a little forwards, to be attached to the inner
border of the dental foramen in the inferior maxillary bone. Between it
and the lower jaw are placed the external pterygoid muscle, the internal
maxillary artery, and the inferior dental nerve. It has no immediate connec-
tion with the joint, and by some anatomists is not recognised as a ligament.
The interarticular fibro- cartilage is a thin plate, placed between the
articular surfaces of the bones. It is of an oval form, broadest trans-
versely, thickest posteriorly, and thinnest at its centre, where it is sometimes
perforated. The inferior surface, which is in contact with the condyle, is
concave ; the superior is concavo-convex from before backwards, conforming
with the articular surface of the temporal bone. Its circumference is
connected at the outside with the external lateral ligament, and anteriorly
with the external pterygoid muscle.
Fig. 123.
Fig. 123. ANTERO-POSTERIOR
SECTION OP THE TEMPORO-
MAXILLARY ARTICULATION
OF THE RIGHT SIDE.
1, is placed close to the
articular eminence, and points
to the superior synovial cavity
of the joint; 2, is placed
close to the articular surface
of the head of the lower jaw,
and points to the inferior
synovial cavity of the joint ;
x , is placed on the thicker
posterior portion of the inter-
articular nbro-cartilage.
Synovial Membranes.
The synovial membrane
which lies between the
interarticular nbro-carti-
lage and the glenoid
cavity is larger and looser than that which is interposed between the fibro-
cartilage and the condyle of the jaw. When the fibro- cartilage is perforated, the
upper and lower synovial cavities necessarily communicate one with the other.
The stylo-maxillary ligament is the name given to a strong or thickened
band of fibres connected with the cervical fascia extending from near the
point of the styloid process to the posterior border of the ramus of the jaw,
where it is inserted between the masseter and internal pterygoid muscles.
It separates the parotid from the submaxillary gland.
It may be proper also to mention in this place the stylo-hyoid ligament t
a thin fibrous cord, which extends from the point of the styloid process to
the lesser cornu of the hyoid bone, and serves to suspend that bone from the
styloid process. A considerable portion of the stylo-hyoid ligament is some-
times converted into bone in the human subject, and in animals it is naturally
osseous, and constitutes the epihyal bone.
MOVEMENTS. The jaw is capable of movements of elevation and depression, of
some degree of lateral displacement, and of protraction and retraction ; but it is
to be observed that when the jaw is depressed, as in opening the mouth, the condyle
advances from the glenoid cayity so as to be placed on the articular eminence in front
134 ARTICULATIONS OF THE UPPER LIMB.
of it. The movements which take place in the superior and inferior compartments
of the joint are of different kinds. In the upper the fibro-cartilage glides backwards
and forwards on the temporal bone ; in the lower compartment the condyle rotates
on a transverse axis against the fibro-cartilage. In opening the mouth the two move-
ments are combined : the jaw and fibro-cartilage together move forwards and rest on
the convex root of the zygoma, while at the same time the condyle revolves on the
fibro-cartilage. When the lower incisors are protruded beyond those of the upper
jaw, the movement is confined chiefly to the upper articulation; and when the same
movement is alternately performed in the joints of opposite sides a horizontal or
grinding motion is produced. The fibres of the external lateral ligament remain
tight both in shutting and opening the mouth, and it is owing to their direction that
in opening the mouth the condyle is driven forwards.
ARTICULATIONS OF THE UPPER LIMB.
THE SCAPULO-CLAVICULAR ARCH.
The supporting arch of the upper limb has only one point of attachment
to the trunk, namely, that at the steruo-clavicular articulation ; the scapula
being connected with the trunk only by muscles.
The clavicle articulates at its inner end with the first bone of the
sternum, and is connected by ligaments to its fellow of the opposite side
and to the first rib. At its outer end it is united to the scapula.
STERNO-CLAVICULAR ARTICULATION". The articular surface of the inner
end of the clavicle is considerably larger than the opposing surface of the
sternum. Between the two bones an interarticular fibro-cartilage is interposed.
The anterior sterno-clavicular ligament, broad and consisting of parallel
fibres, passes from the inner extremity of the clavicle in front downwards
and inwards, upon the anterior surface of the sternum.
The posterior sterno-clavicular ligament, lying on the thoracic aspect of the
joint, is of similar conformation with the anterior ligament, but is not so
broad or strongly marked.
The interarticular fibro-cartilage, nearly circular in its form, and thicker
above and at the border than at the centre, is interposed between the arti-
culating surfaces of the sternum and clavicle. Towards its upper part it is
attached to the inner and upper part of the clavicle, and at its lower edge
to the cartilage of the first rib. In the latter situation it is thin and some-
what prolonged, so that the inferior border of the clavicle rests upon it.
Synovial membranes. In this articulation, as in that of the lower jaw,
there are two cavities lined by synovial membrane, one on each side of the
interarticular fibro-cartilage.
The interclavicular ligament is a dense fasciculus of fibres, between the
contiguous extremities of the clavicles. It dips downwards in the middle,
and is connected with the upper margin of the sternum, filling up a part of
its interclavicular notch.
The costo-clavicular ligament (ligamentum rhomboides Weitbrecht) does
not properly form part of the sterno-clavicular articulation ; yet it con-
tributes materially to retain the clavicle in its situation. It is attached
iuferiorly to the cartilage of the first rib near its sternal end, and passes
obliquely backwards and upwards, to be fixed to a rough depression at the
under surface of the clavicle near the sternal end.
SCAPULO-CLAVICULAR CONNECTIONS. At its outer end the clavicle articu-
lates with the acromion, and is connected by ligamentous fibres with the
coracoid process.
The acromio- clavicular articulation is a synovial joint uniting the outer
ARTICULATIONS OF THE CLAVICLE AXD SCAPULA.
135
extremity of the clavicle with the inner edge of the acromion. It is sup-
ported above by a thick and broad superior ligament, and below by an
inferior ligament which is not so strong. An interarticular fibro-cartilage is
frequently present, but is sometimes wanting. It is usually wedge-shaped,
attached by its base to the upper part of the joint, and only partially sepa-
rating the small oval articular surfaces.
Fig. 124.
Fig. 124. VIEW FROM BEFORE OF THE ARTICULATIONS OF THE SHOULDER BONES. ^
1, acromio-clavicular articulation ; 2, conoid, and 3, trapezoid part of the coraco-
clavicular ligament ; 4, is near the suprascapular or coracoid ligament ; 5, placed on
the coracoid process, points to the coraco-acromial or deltoid ligament ; 6, is placed on
the front of the capsular ligament of the shoulder -joint ; 7, the coraco-humeral ligament
or accessory part of the capsular ; above 6, an aperture in the capsular ligament at the
place where a part of the tendon of the subscapularis muscle pierces the capsular liga-
ment, and is sometimes connected with a synovial bursa ; 8, tendon of the glenoid head
of the biceps muscle issuing between the tuberosities ; 9, right half of the interclavicular
ligament ; 10, interarticular fibro-cartilage of the sterno-clavicular articulation, shown by
removing the anterior sterno-clavicular ligament and synovial membrane ; 11, the costo-
clavicular or rhomboid ligament ; 12 and 13, the cartilage and small part of the second
and third ribs attached by their anterior costo-sternal ligaments. (See also Fig. 120.)
The coraco- clavicular ligament, which connects the clavicle with the
coracoid process of the scapula, is divisible into two parts, each known by
a particular name. The conoid ligament, which is the posterior cr internal
fasciculus, broad above, narrow below, is attached inferiorly to the inner
part of the root of the coracoid process, and superiorly to a tubercle on the
inferior surface of the clavicle below the convex margin of its outer curve :
its fibres are directed backwards and upwards. The trapezoid ligament t the
anterior or external fasciculus, slopes upwards, backwards, and outwards
from the inner border of the coracoid process to an oblique line extending
outwards from the tubercle to which the conoid ligament is attached, and is
inserted at right augles to the line of attachment of that ligament to the
136 ARTICULATIONS OF THE UPPER LIMB.
clavicle. In the angle between the conoid and trapezoid ligaments there is
frequently present a synovial bursa.
MOVEMENTS. The movements allowed at the clavicular articulations are limited,
not so much by the forms of the articular surfaces, as by the costo-clavicular and coraco-
clavicular ligaments, and the position of the thoracic wall. When the clavicle is
forcibly depressed, as in lifting a heavy weight, it presses upon the first rib,
the upper border of its inner end rises above the sternum, and the interarticular
cartilage and interclavicular ligament are put upon the stretch. When the
shoulders are drawn backwards and downwards, the angle between the clavicle and
the upper border of the scapula is increased, by the descent of the scapular arch on the
conical wall of the thorax. In raising and depressing the arm to its full extent, there
is not only vertical motion at the shoulder joint, but also motion at the sterno-clavi-
cular and acromio-clavicular articulations.
LIGAMENTS OF THE SCAPULA. There are two ligaments which stretch from
one part of the scapula to another. 1. The coracoid or suprascapular ligament
(liganienturn proprium posterius), is a thin flat band of fibres, attached by its
extremities to the opposite margins of the notch at the root of the coracoid
process, which it thus cou verts into a foramen for the transmission of the
supra- scapular nerve, the corresponding artery most commonly passing above
it. 2. The coraco-acromial ligament (ligamentum proprium anterius), broad,
firm, and triangular, is attached by its broader extremity to the outer edge
of the coracoid process, and by the narrower to the tip of the acromion. Its
inferior surface looks downwards upon the shoulder joint, the superior is
covered by the deltoid muscle.
THE SHOULDER-JOINT.
In this articulation the large and hemispherical head of the humerus ia
opposed to the much smaller surface of the glenoid cavity of the scapula.
The bones are retained ID position, not by the direct tension of strong liga-
ments, which would have restricted too much the movements of the joint,
but by surrounding muscles and atmospheric pressure.
The capsular ligament is attached to the scapula round the margin of the
glenoid cavity, and to the humerus at the place where the neck springs from
the tuberosities and shaft. It extends furthest down the humerus on the
internal or inferior aspect, and is strongest on the superior aspect. The laxity
of the capsule is such that the humerus drops away from the glenoid cavity
-__ Fig. 125. VIEW OF THE GLENOID CAVITY AND LIGA-
MENTS BETWEEN THE SCAIULA AND CLAVICLE OF 1
THE RIGHT SIDE. ^
1, glenoid fossa, its cartilaginous surface ; 2, the
glenoid ligament or fibrous border; 3, the tendon of
the biceps muscle seen in connection with the upper
part of the glenoid fossa and ligament; 4, is placed
on the upper surface of the coracoid process ; 5 and 6,
on the adjacent part of the clavicle ; 4 to 5, the conoid ;
4 to 6, the trapezoid portion of the coraco-clavicular
ligament; 7, is placed on the apex of the acromion
process ; 4 to 7, the coraco-acromial ligament ; 8, is
above the acromio-clavicular articulation, which is
represented as open anteriorly, showing a wedge-
shaped interarticular cartilage attached above to the
superior acromio-clavicular ligament; x, the inferior
acromio-clavicular ligament.
as soon as its muscular connections are detached. Superiorly and posteriorly
the capsule is strengthened by the tendons of the supraspinatus, infraspiuatus,
THE SHOULDER-JOINT.
137
and teres minor muscles, which are intimately connected with it, as they pass
over it to reach the great tuberosity of the humerus. Anteriorly the tendon
of the subscapularis muscle comes into direct contact with the synovia! mem-
braiie, which is prolonged upon it through an oval opening. The insertion
of the capsule is likewise interrupted opposite the bicipital groove, to give
passage to the long tendon of the biceps muscle.
The coraco-humeral, or accessory ligament, is a broad bundle of fibres
extending obliquely over the upper and outer part of the articulation ; it is
attached to the root of the coracoid process, and thence descends towards
the greater tuberosity of the humerus, intimately connected with the capsule.
The glenoid ligament is a firm fibrous band, about two lines deep, which
is fixed to the edge of the glenoid fossa, and, by elevating the border of the
cavity, renders it a little deeper. The upper part of it is connected with the
tendon of the long head of the biceps muscle, which is also fixed into the
upper part of the glenoid fossa, within the capsule of the joint.
The synovial membrane is reflected uninterruptedly from the glenoid
cavity on the inner surface of the fibrous capsule to the humerus, but its
form is complicated by its relation to the tendons of the biceps and sub-
scapularis muscles. The long tendon of the biceps muscle, traversing the
joint in its course from the upper border of the glenoid cavity to the bicipital
groove, is enclosed in a tubular sheath, formed by an offset or process of the
synovial membrane, which is continued down upon it beyond the fibrous
capsule into the bicipital groove, and is thence reflected upwards upon it to
Fig. 126.
Fig. 126. A, SECTION THROUGH THE SHOULDER-JOINT, PASSING FROM WITHIN OUTWARDS
THROUGH THE TENDON OF THE BlCEPS AND BlOIPITAL GROOVE, SOMEWHAT DIAGRAM-
MATIC, TO SHOW THE SYNOVIAL CAVITY OF THE JOINT, &C. ^
B, OUTLINE OP THE SAME, TO SHOW THE INFLECTION OP THE SYNOVIAL MEMBRANE
OVER THE TENDON.
1, placed above the sawn end of the outer part of the clavicle ; 2, is near the acromial
end; 3, the cavity of the shoulder-joint close to the upper part of the glenoid head,
where there are seen the section of the cartilages on the head of the humerus and in the
glenoid cavity of the scapula, the glenoid ligament, and the origin of the tendon of the
biceps muscle ; 4, is in the lower part of the cavity of the joint, indicating the section of
the glenoid ligament in that situation ; 5, the upper part of the capsular ligament and
synovial membrane ; 6, the tendon of the biceps as it passes out of the joint into the
bicipital groove ; 6', 6', the tubular prolongation of the synovial membrane round the
tendon ; 7, the reflection of the synovial membrane on the humerus within the lower part
of the capsular ligament.
138 ARTICULATIONS OF THE UPPER LIMB.
its origin, where it again becomes continuous with the synovial membrane
of the capsule in such a manner as to preserve the integrity of the mem-
brane. The bursal prolongation of the synovial membrane on the tendon of
the subscapularis muscle is of variable extent, sometimes scarcely existing,
sometimes forming a considerable pouch on the venter of the scapula.
Subacromial Bursa. Superficial to the muscles covering the top of the
joint is a considerable bursa mucosa, by means of which the contiguous sur-
faces of the coracoid and acromion processes, and of the coraco-acromial
ligament and deltoid muscle, are lubricated, so as to facilitate the movements
of the subjacent head of the humerus.
MOVEMENTS. Great freedom of movement of the humerus in every direction is
admitted at the shoulder-joint ; but superiorly and posteriorly the extent of the move-
ment is somewhat limited by the margin of the acromion. When the arm is raised,
the great tuberosity of the humerus becomes locked against the acromion as soon as the
position is reached in which the limb lies at right angles to the trunk, and all further
elevation is accomplished by movements in the sterno-clavicular and acromio-clavicular
articulations. The arch formed by the acromion, the coracoid process, and the deltoid
ligament, lined by the subacromial bursa, forms a sort of secondary socket, in which
the extremity of the humerus, covered by the tendons inserted into the great tube-
rosity, revolves, and against which it is pressed when the weight of the body is made
to rest upon the arms : in quadrupeds, the weight of the body is transmitted through
the glenoid fossa to the humerus.
ARTICULATIONS OF THE FOREARM AND ELBOW.
UNION OF THE RADIUS AND ULNA. The bones of the forearm are united
by a superior and an inferior articulation and an interosseous membrane.
Fig. 127. THE UPPER PART OP THE ULNA, WITH THE
ORBICULAR LIGAMENT OP THE RADIUS. ^
] , upper division of the sigmoid surface on the olecranon ;
2, extremity of the coronoid process ; 5, orbicular liga-
ment.
In the superior radio-ulnar articulation, the con-
nection of the head of the radius with the small sig-
moid cavity of the ulna is effected by means of the
annular or orbicular ligament, a strong baud of fibres
attached to the ulna in front and behind at the ex-
tremities of the small sigmoid cavity, and forming
four- fifths of a ring which encircles the head of the
radius and binds it firmly in its situation. The outer
surface is connected with the external lateral ligament
of the elbow, whose fibres are inserted into it ; the
deep surface is smooth, and is lined by the synovial
membrane of the elbow-joint.
The inferior radio-ulnar articulation. The connection between the semi-
lunar surface of the radius and the lower end of the ulna is effected by
means of a fibro-cartilage, a synovial membrane, and some scattered liga-
mentous fibres in front and behind. The triangular fibro-cartilage is a thick
plate attached by its base to a ridge separating the carpal from the ulnar
articulating surface of the radius ; and by its apex to a depression at the
root of the styloid process of the ulna, and to the side of that process. Its
upper surface looks towards the ulna, its lower towards the cuneiform bone,
RADIO-ULNAR ARTICULATION.
139
and it separates the inferior radio-ulnar articulation from the wrist-joint.
The synovial membrane, sometimes called from its looseness membrana sacci-
formis, extends partly upwards between the
radius and ulna, partly horizontally inwards
between the ulna and triangular fibro-carti-
lage. When the fibro-cartilage is perforated,
as is occasionally the case, this synovial mem-
brane is continuous with that of the wrist-
joint.
Fig. 128. THE LOWER PARTS OF THE RADIUS AND
ULNA, WITH THE TRIANGULAR FIBRO-CARTILAQE
CONNECTING THEM. f
1, ulna ; 2, its styloid process ; 3, radius ; 4, the
part of the articular surface for the scaphoid
bone ; 5, that for the semilunar bone ; 6, lower
surface of the triangular nbro-cartilage ; * *, a piece
of whalebone passed between the nbro-cartilage and
the ulna.
Fig. 129.
The interosseous mem-
brane or ligament of the
forearm is a thin, flat,
fibrous membrane, the
direction of whose fibres
is for the most part ob-
liquely downwards and
inwards, and which
extends between the
contiguous borders of
Fig. 129. A, FRONT, AND
B, BACK VIEW OP THE
ARTICULATIONS OP THE
FOREARM, WRIST AND
HAND.
1, the internal lateral
ligament of the elbow-joint;
2, the external lateral ; 3,
the anterior; 4, points to
the posterior ; 5, orbicular
ligament of the radius ; 6,
interosseous membrane ; 7,
oblique or round ligament ;
8, internal lateral ligament
of the wrist ; 9, external ;
10, anterior; 11, posterior;
12, palmar, and 13, dorsal
carpo - metacarpal liga-
ments ; 14, ligaments con-
necting metacarpal bones ;
15, transverse metacarpal
ligament ; 16, carpo- meta-
carpal ligament of the
thumb ; 17, lateral liga-
ments connecting the pha-
langeal with the metacarpal
bones; 18, lateral liga-
ments of the phalanges.
140
ARTICULATIONS OF THE UPPER LIMB.
the radius and ulna. Its superior border is placed about an inch below
the tubercle of the radius, leaving a space (hiatus interosseus) through
which the posterior iuterosseous vessels pass. This space is diminished in
size by the round or oblique ligament, a thin, narrow fasciculus of fibres ex-
tending obliquely downwards and outwards from the coronoid process, to be
attached to the radius about half an inch below the tubercle. Other small
bundles of fibres, having the same direction as the round ligament, are often
to be found at intervals, decussating with the fibres of the interosseous
ligament on its posterior surface.
MOVEMENT OP THE RADIUS ON THE ULNA. The disposition of the annular liga-
ment allows the head of the radius to rotate freely within it, while the lower end of
the radius, bound by the triangular fibro-cartilage to the styloid process of the ulna,
has a freedom of circumduction round that point, by which the hand is brought into
the prone or the supine position. Thus in pronation and supination the movement
of the radius describes a part of a cone, the axis of which extends from the centre of
the head of the radius to the styloid process of the ulna.
THE ELBOW- JOINT. The lower extremity of the humerus is in contact
with the ulna and radius at the elbow, and forms with them a hinge-joint.
The greater sigmoid cavity of the ulna articulates with the trochlea of the
humerus, so as to admit of flexion and extension only ; while the cup-
shaped depression on the head of the radius is fitted to turn freely on the
rounded capitulum. These bones are united principally by lateral ligaments.
Fig. 130. LIGAMENTS OP THE ELBOW-JOINT. J
A, from the outer side and behind ; B, from the front ; C, from the inner side and
behind. 1, internal lateral ligament ; 2, external lateral ; 3, the middle strongest part
of the anterior ligament ; 4, orbicular ligament ; 5, posterior, represented as wrinkled
from relaxation in extension. In these figures the round ligament and upper part of the
interosseous membrane are also represented below the elbow -joiut.
THE ELBOW-JOINT.
The internal lateral ligament, composed of diverging and radiating fibres,
is divisible into an anterior and a posterior part. The anterior part radiates
from the front of the internal condyloid eminence of the humerus, and is
inserted into the coronoid process, along the inner margin of the sigmoid
cavity. The posterior part, of the same triangular form, passes from the
under and back part of the condyloid eminence downwards to the inner
border of the olecranon ; and some fibres are connected with a small transverse
band over the notch between the olecrauon and the coronoid process.
The external lateral ligament, intimately connected with the tendinous
attachment of the extensor muscles, is shorter and much narrower than the
internal. It is attached superiorly to the external condyloid eminence of
the humerus, and inferiorly becomes blended with the annular ligament
of the radius ; some of its hinder fibres are prolonged to the external margin
of the ulna.
The anterior ligament consists of a thin sheet of fibres extending down-
wards from above the coronoid pit of the humerus, and protecting the
anterior part of the synovial membrane ; it is strongest in its middle part.
The posterior ligament is comparatively thin
and weak, and consists of loose and irregular fibres Fig. 131.
passing transversely across the olecranon fossa of the
humerus, and from the sides of that fossa to the
olecranon process, thus completing the capsule of
the joint behind.
Fig. 131. VERTICAL ANTERO-POSTERIOR SECTION OP THE
ELBOW-JOINT THROUGH THE GREATER SIGMOID CAVITY
OF THE ULNA AND CORRESPONDING TROCHLKAR SURFACE
OF THE HUMERUS. J
1, cut surface of the humerus ; 2, that of the ulna ; 3,
posterior part, and 4, anterior part of the synovial cavity of
the joint ; 5, orbicular ligament enclosing the head of the
radius ; 6, tendon of the biceps muscle at its insertion into
the tuberosity ; 7, is at the lower end of the round ligament.
The synovial membrane extends upwards on the
humerus so far as to line the fossse for the coronoid
and olecranon processes, and is loose and vascular in
the latter positions. It is prolonged round the head
and neck of the radius, which it separates from the
smaller sigmoid cavity and annular ligament.
MOVEMENTS. Flexion and extension are the only movements which can take place
between the humerus and ulna ; aud these are limited by the locking of the coro-
noid and olecranon processes in the respective fossae of the humerus which receive
them. The path of motion is in a nearly vertical plane, with a direction slightly
outwards. The inner lip of the trochlea being prominent below, forms an expansion
which corresponds to an inward projection of the coronoid part of the ulnar surface,
and is only brought into use in flexion ; and the outer lip of the trochlea, being everted
at the upper and back part, forms a surface which is only in use in complete extension,
and which then corresponds to a surface on the outer aspect of the olecranon, which
comes into contact with no other part of the humerus. In flexion and extension the
radius moves by its cup-shaped head upon the capitulum, and on the groove between
that process and the trochlea, by a ridge internal to the cup. It is most completely
in contact with the humerus in the position of semi-flexion and semi-pronation. In
full extension and supination, the anterior margin of the head of the radius is barely
in contact with the inferior surface of the capitulum. In full flexion, the margin of
the head of the radius rests against the pit above the capitulum.
142 ARTICULATIONS OF THE UPPER LIMB.
THE WRIST- JOINT AND ARTICULATIONS OF THE HAND.
THE RADIO-CARPAL ARTICULATION, or wrist-joint, is formed between the
radius and triangular fibre-cartilage above, and the scaphoid, semilunar and
cuneiform bones below. The superior surface, concave both transversely and
from before backwards, is subdivided by linear elevations into three parts cor-
responding to the three bones below, the innermost part being formed by the
fibro-cartilage. The inferior surface, convex in both directions, is prolonged
further down upon the carpal bones behind than in front.
The internal lateral ligament is a rounded cord passing directly down-
wards from the extremity of the styloid process of the ulna, to be attached
to the cuneiform bone ; it also sends some fibres to the anterior annular
ligament and the pisiform bone.
The external lateral ligament extends from the styloid process of the
radius to a rough surface on the outer side of the scaphoid bone, some of
its fibres being prolonged to the trapezium, and also to the anterior annular
ligament of the wrist.
The anterior ligament (radio-carpal), broad and membranous, consists
partly of fibres which have a nearly transverse direction, partly of others,
which diverge as they descend from the anterior border of the radius to the
scaphoid, semilunar, and cuneiform bones : some of them are continued to
the os magnum.
The posterior ligament extends obliquely downwards and inwards, from
the extremity of the radius, to the posterior surface of the first row of the
carpal bones, especially the cuneiform bone ; its fibres are prolonged some
distance on the surface of the carpal bones.
The synovial membrane is reflected from the radius and the triangular
fibro-cartilage, on the surrounding ligaments, and, after lining these, passes
to the opposed surface of the carpal bones.
THE CARPAL ARTICULATIONS. The bones of the carpus, the pisiform
excepted, are so arranged in two rows, that while only slight movement can
take place between the members of each row, a considerable amount of
movement is possible between the two rows. The surface presented by the
first row to the second is concave both transversely and from before back-
wards in the greater part of its extent, but at its outer side it is bounded by
the convex part of the scaphoid bone. The opposing surface of the second
row is concavo-convex from without inwards, the concavity being formed by
the trapezium and trapezoid, the convexity by the os magnum and unciform
bone.
The two rows of carpal bones are united by dorsal, palmar, and lateral
ligaments. The lateral ligaments are placed one at the radial, the other at
the ulnar border of the carpus ; the former connects the scaphoid bone with
the trapezium, the latter the cuneiform with the unciform. The dorsal
ligaments consist of fibres passing in various directions ; the palmar ligaments
are chiefly composed of fibres converging towards the os magnum.
The bones of the first row, the pisiform bone excepted, are united by inter-
osseous, and by dorsal and palmar ligaments. The interosseous ligaments,
placed on the sides of the semilunar bone on a level with its superior sur-
face, connect it with the scaphoid and cuneiform bones, thus completing the
inferior wall of the radio-carpal joint. The dorsal and palmar ligaments,
each two in number, extend transversely on the dorsal and palmar surfaces
from the scaphoid bone to the semilunar, and from the semilunar to the
cuneiform.
CARPAL ARTICULATIONS.
143
The bones of the second row are connected by similar means. The dorsal
and palmar ligaments, each three in number, pass transversely between the
contiguous bones. The interosseous ligaments are generally three (but
Fig. 132.
Fig. 132, A. DORSAL VIEW OP THE DEEPER LIGAMENTS OP THE WRIST-JOINT, AND OP
THE CARPAL AND CARPO-METAOARPAL ARTICULATIONS (after Arnold). \
1, lower part of the ulna ; 2, external lateral ligament of the wrist-joint ; 3, internal ;
near it, descending obliquely to 6, from the radius, the dorsal radio-carpal ligament ;
4 to 5, transverse dorsal ligaments of the first row : 4, is on the scaphoid ; 5, on the
semilunar bone ; 6, cuneiform bone, with the attachment of the dorsal radio-carpal liga-
ment; 7, trapezium ; 8, trapezoid ; 9, os magnum; 10, unciform ; 11 to 15, first to fifth
metacarpal bones; 7 to 8, 8 to 9, and 9 to 10, transverse dorsal ligaments of the second
row of carpal bones ; 4 to 8, 4 to 9, 5 to 9, and others, dorsal ligaments between the first
and second row; 8 to 12, 9 to 13, and others, dorsal ligaments from the second row to
the metacarpal bones; between the metacarpal bones, from 11 to 15, the dorsal inter-
metacarpal ligaments.
Fig. 132, B. PALMAR VIEW OP THE LIGAMENTS OP THE WRIST-JOINT, AND OF THE
CARI-AL AND CARPO-METACARPAL ARTICULATIONS. |
The anterior radio-carpal ligament has been removed : 1, anterior ligament of the lower
radio-ulnar articulation ; 2, external, and 3, internal lateral ligament of the wrist-joint ;
4, scaphoid bone ; 5, semilunar ; 6, cuneiform ; 7, pisiform, with the tendon of flexor
carpi ulnaris attached ; 4 to 5, and 5 to 6, palmar transverse ligaments of the first row ;
8, external lateral ligament between the first and second row of carpal bones ; 9, trape-
zium (the trapezoid is not numbered) ; 10, os magnum ; 11, hooked process of the unci-
form bone ; 9 to 10, 10 to 11, and others, transverse palmar ligaments of the second row ;
4 to 10, and 6 to 10, some of the palmar ligaments uniting the two rows, converging on
the os magnum ; 7 to 11, ligament from the pisiform bone to the unciform process ;
7 to 16, ligament from the pisiform to the fifth metacarpal bone; 12, external ligament
of the first carpo-metacarpal articulation, the internal of which is also shown ; 13, 14,
15, 16, the proximal ends of the second to the fifth metacarpal bones, on which the
palmar transverse, and on three of them, a set of piso-metacarpal ligaments are shown.
sometimes only two) in number, a strong ligament being placed between the
os magnum and unciform bones, another between the trapezoid and trapezium,
and a slender ligament between the os magnum and trapezoid. A small
interosseous ligament is also sometimes found between the os magnum and
the scaphoid. (Fig. 133.)
144
ARTICULATIONS OF THE UPPER LIMB.
The synovial cavity of the carpal articulations is extensive and complicated.
Passing between the two rows of carpal bones, it sends likewise two processes
between the three bones of the first row, and three between the four bones
of the second. It is further continued downwards into the four lower carpo-
metacarpal and three intermetacarpal articulations of the ulnar side. In some
rare cases there is continuity with the synovial membrane of the wrist-joint,
by deficiency of one of the interosseous ligaments between the carpal bones.
Fig. 133.
li
Fig- 133. TRANSVERSE SECTION OP THE SY-
NOVIAL CAVITIES OP THE INFERIOR RADIO-
ULNAR, RADIO-CARPAL, INTERCARPAL, AND
CARPO-METACARPAL ARTICULATIONS. |
1, points to the triangular fibre-cartilage
below the ulna ; 2, placed on the ulna, points
to the cavity of the sacciform synovial mem-
brane ; 3, external lateral, and 4, internal
lateral ligament, and between them the synovial
cavity of the wrist ; 5, scaphoid bone ; 6, semi-
lunar ; 7, cuneiform ; 8, 8, upper portion, and
8', 8', lower portion of the general synovial
cavity of the intercarpal and carpo-metacarpal
articulations ; between 5 and 6, and 6 and 7,
the interosseous ligaments are seen separating
the carpal articular cavity from the wrist-
joint ; between the four carpal bones of the
lower row, and between the magnum and
scaphoid the interosseous ligaments are also
shown ; the upper division of the synovial
cavity communicates with the lower between
10 and 11, and between 11 and 12 ; x, marks
one of the three interosseous metacarpal liga-
ments ; 9', separate synovial cavity of the first
carpo-metacarpal articulation ; 13, first, and 14, fifth, metacarpal bone.
NOTE. It is to be observed that in this figure, and in others of a like kind which
represent the joint-cavities, the white or black lines indicating the synovial membranes
are, for the sake of clearness, generally represented as passing over the surfaces of the
articular cartilages, although this is not the case in nature. These lines therefore must
be held to represent merely the whole continuity of the articular, or, as they are often
called, the synovial surfaces.
The pisiform bone is articulated by a fibrous capsule and synovial mem-
brane with the cuneiform bone. Inferiorly it is united by two strong liga-
ments with the unciform and fifth metacarpal bones, and is sometimes also
connected with other metacarpal bones ; superiorly it receives the tendon
of the flexor carpi ulnaris muscle. The synovial membrane is usually distinct,
but sometimes communicates with that of the radio-carpal articulation.
The anterior annular ligament of the wrist is a strong and thick band,
which extends from the prominences made by the trapezium and scaphoid
bone on the radial side of the carpus, directly across to the pisiform bone
and unciform process, and converts the transverse arch of the carpus into
a ring through which the flexor tendons of the digits pass into the hand.
The posterior annular liyament, placed at the back of the wrist, is only
a thickened part of the aponeurosis of the forearm. It extends from the
lower part of the radius, at its outer border, to the inner part of the cunei-
form and pisiform bones, and serves to bind down the extensor tendons.
CONNECTION OP THE METACARPAL BONES WITH THE CARPUS, AND WITH
EACH OTHER.
The four inner metacarpal bones are bound together at their distal extre-
mities by thin fibres passing between them, and constituting on their palmar
METACAKPAL AND PHALANGEAL ARTICULATIONS.
U5
aspect, the transverse ligament. At their proximal extremities they are
united to one another and to the carpal bones in articulations, the common
synovial lining of which is derived from that of the carpal joint. In these
articulations the four metacarpal bones are bound together by three dorsal,
and three palmar, and by strong interosseous ligaments. There are also
dorsal ligaments uniting these metacarpal bones with the carpus, each having
two such ligaments except the fifth. Thus to the second, or that of the fore-
finger, a thin fasciculus of fibres passes from the trapezium, and another
from the trapezoid bone ; the third receives one from the trapezoid, and
from the os magnum; the fourth from the os magnum and also from the
unciform ; but the fifth is connected with the unciform only. The palmar
ligaments are not so well defined ; there is a single band to each bone,
except that of the little finger. There is likewise an interosseous band in
one part of the carpo-metacarpal articulation, connecting the lower and
contiguous angles of the os magnum and unciform to the adjacent angle of
the third metacarpal bone. This ligament is usually surrounded by a part
of the general synovial membrane, but sometimes it separates the cavity be-
tween the unciform and two inner metacarpal bones from the rest of the joint.
The first metacarpal bone is unconnected with the others, and is articu-
lated with the trapezium by an external and an internal ligament, a capsular
investment, and a distinct synovial membrane.
ARTICULATIONS OF THE METACARPAL BONES WITH THE PHALANGES, AND OP
THE PHALANGES WITH EACH OTHER.
Fig. 134.
The rounded head of each of the last
four metacarpal bones, being received inta
the slight concavity in the extremity of
the first phalanx, is maintained in its
position by two lateral ligaments, an an-
terior ligament, and a synovial mem-
brane.
The lateral ligaments consist of dense
and thick fasciculi of fibres, placed one at
each side of the joint ; they are attached
each by one extremity to the side of the
Fig. 134. GENERAL VIEW OP THE ARTICULATIONS
OF THE WRIST AND HAND FROM BEFORE.
1, lower part of the interosseous membrane ; 2,
and from that point across the lower end of the
radius, the palmar radio-carpal ligaments ; 3, sca-
phoid bone ; 4, pisiform ; 5, trapezium ; 6, unci-
form ; 7, os magnum, with most of the deeper
ligaments uniting these bones ; I, first metacarpo-
phalangeal articulation with its external lateral
ligament; II to V, transverse metacarpal liga-
ment : in the several phalangeal articulations the
lateral ligaments are shown ; in the first the
external only is visible.
metacarpal bone, and by the other to the
anterior ligament and the contiguous ex-
tremity of the phalanx. The direction of
the fibres is downwards and forwards.
The anterior or palmar ligament, or rather fibrous plate, occupies the
interval between the lateral ligaments on the palmar aspect of each joint ; it
146
ARTICULATIONS OF THE UPPER LIMB.
Fig. 135.
is a thick and dense fibro-cartilaginous structure, which is firmly united to
the first phalangeal bone, and but loosely adherent to the metacarpal. It is
continuous at each side with the lateral ligament, so
that the three form one undivided structure which
covers the joint, except on the dorsal aspect. Its
palmar surface is grooved for the flexor tendon, whose
sheath is connected to it at each side : the other sur-
face, looking to the interior of the joint, is lined by the
synovial membrane, and supports the head of the
metacarpal bone. In the joint of the thumb there
are two sesamoid bones, one situated at each side, which
are connected with its ligaments.
Fig. 135. LONGITUDINAL ANTERO-POSTERIOR SECTION THROUGH
THE LOWER PART OP THE RADIUS, THE CARPUS, SEMILUNAR
BONE, Os MAGNUM, METACARPAL BONE, AND PHALANGES OF
THE MIDDLE FINGER, TO SHOW THE SHAPE OF THE ARTI-
CULAR SURFACES AND SYNOVIAL CAVITIES BETWEEN THESE
SEVERAL BONES. ^
1, synovial cavity of the wrist-joint ; 2, intercarpal cavity ;
3, carpo-metacarpal cavity ; 4, metacarpo-phalangeal cavity ;
5 and 6, phalangeal cavities ; 4', 5', and 6', the palmar fibro-
cartilaginous plates which are attached to the base of the several
phalanges; 7, indicates the place of the tendons of the long
flexor muscles ; 8, a transverse section of the anterior annular
ligament ; 9 and 10, transverse retinacula or vaginal ligaments
of the flexor tendons on the first and second phalanges.
A synovial membrane is present in each joint, and
invests the surface of the ligaments which connect the
bones.
The phalanges are articulated with one another t on
the same plan as that which obtains in the articulations
between the bases of the proximal phalanges with the
metacarpal bones.
MOVEMENTS OF THE WRIST AND FINGERS. In the radio-carpal and common carpal
articulations, there is allowed not only flexion and extension, but a certain amount of
lateral bending. The superior articular surfaces of both ranges of carpal bones being
prolonged further on the dorsal than on the palmar aspect, over-extension is allowed
in both joints to some degree. In over-extension the opposing surfaces are most per-
fectly adapted to each other ; in flexion, they are least so. The kind of movement
which is allowed between the carpal and metacarpal bones is best illustrated by placing
the hand in such a position that the weight of the body is rested upon the open palm.
The metacarpal range, which naturally is concave towards the palm, is flattened ; and
the metacarpal inter osseous and palmar ligaments are thus tightened, while a slight
separation of the opposed surfaces of the bones takes place ; so also the palmar carpo-
metacarpal ligaments are tightened, and both palmar and interosseous ligaments of
the second range of carpal bones. The convex part of the os magnum and unciform
bone, fitted in those circumstances into the concavity of the first range, is a little wider
than the part usually in contact with it; and thus, while the bones of the first range
are separated from the distal side, those of the second range are pressed still more
separate from the palmar aspect. The whole arrangement secures elasticity. The
fourth and fifth metacarpal bones, being more moveable at their carpal articulation
than the second and third, bend forward very distinctly in shutting the hand, thus
rendering the palm more hollow, and bringing the tips of the fingers more closely
together : the movement is one of coaptation. At the phalangeal articulations the
only movement allowed is that of flexion and extension, and over-extension is pre-
vented by the ligamentous structures in front of the joints. At the metacarpo-
SACRO-VERTEBRAL AND SACRO-ILIAC ARTICULATIONS. 14?
phalangeal articulations there is allowed, in addition, a movement of abduction and
adduction, but that chiefly in the extended position. In the articulation of the meta-
carpal bone of the thumb with the trapezium every movement is allowed except
rotation, which is prevented by the shape of the articular surfaces.
ARTICULATIONS OF THE PELVIS.
ARTICULATION OF THE PELVIS WITH THE LAST LUMBAR VERTEBRA. The
fifth lumbar is united to the first sacral vertebra by anterior and posterior
ligaments of the body, ligamenta subflava of the arch and interspinous
ligaments, and by an inter vertebral plate, all of which are similar to those
between the vertebrae above. It is also attached to the pelvis by two other
ligaments, as follows.
The sacro-vertebral ligament extends obliquely from the tip of the trans-
verse process of the last lumbar vertebra downwards to the depressed lateral
part of the base of the sacrum ; its form is triangular, and its fibres diverge
as they descend, some of them joining the anterior sacro-iliac ligament.
The ilio-lumbar ligament is extended horizontally between the summit of
the transverse process of the last lumbar vertebra and the iliac crest of the
innominate bone ; it is inserted into the latter at the back part of the iliac
fossa, where its fibres expand somewhat, so as to give it a triangular form.
ARTICULATION OF THE SACRUM AND COCCYX, AND OP THE PIECES OF THE
COCCYX. These articulations are effected by an anterior ligament, consisting
of irregular fibres placed in front of the bones, a prolongation of the
anterior common ligament of the vertebrae ; by a posterior ligament more
strongly marked, composed of fibres which descend upon the bones of the
c >ccyx from the margin of the inferior orifice of the sacral canal ; and by
inter vertebral discs between the contiguous surfaces of the bones.
A synovial membrane has been stated by Cruveilhier (" Anatomic descriptive,"
torn. i. p. 356. Paris, 1834), to be present in those cases in which the coccyx is freely
moveable. This is in conformity with the more recent observations of Luschka on
the other intervertebral discs. In the male, after middle life, the union between the
sacrum and coccyx, and between the pieces of the latter, is usually ossific. In
the female this change does not generally occur till a more advanced age; the
pieces of the coccyx uniting one to another in the first place, and the joint between
the sacrum and coccyx not ossifying till old age. The mobility seems to increase
during pregnancy.
THE SACRO-ILIAC ARTICULATION, often named the sacro-iliac synchondrosis,
is formed between the adjacent portions of the sacrum and ilium, the auri-
cular surfaces of which are coated with cartilage, and the remaining parts
are united by strong ligaments (see fig. 139).
The auricular cartilaginous plate unites the bones with great firmness.
When the ilium and sacrum are forcibly torn asunder, this plate usually
separates into two layers, one of which adheres to the surface of each bone.
In some instances a small cavity naturally exists between these two plates
of cartilage. Even when separated in part, however, these plates are very
closely applied, and admit only a limited amount of movement. They are
then sometimes slightly united by delicate tissue, and in advanced life, small
spaces containing glairy fluid are liable to be formed between them. The
cavity of this articulation becomes more apparent, and the ligaments some-
what looser before parturition.
The posterior sacro-iliac ligament, much the thicker, consists of a large
number of strong irregular fibres extending across the interval between the
posterior rough portion of the lateral surface of tho sacrum and that part of
L 2
148 ARTICULATIONS OF THE PELVIS.
the ilium which projects beyond the dorsum of the sacrum. A superficial
band extending downwards from the posterior superior iliac spine to the
third or fourth piece of the sacrum, in a direction different from the other
fibres, is distinguished as the oblique sacro-iliac ligament.
The anterior sacro- iliac ligament consists of thin irregular fibres passing
between the sacrum and os innominatum on their pelvic surfaces.
Fig. 136.
i
Fig. 136. ARTICULATIONS OF THE PELVIS AND HIP-JOINT, SEEN FROM BEFORE. THE
ANTERIOR HALF OF THE CAPSULAR LlGAMENT OF THE LEFT HlP-JoJNT HAS BEEN
REMOVED, AND THE FEMUR ROTATED OUTWARDS. \
1, 1, anterior common ligament of the bodies of the vertebrae passing down over the
two lowest lumbar vertebrae to the front of the sacrum and coccyx ; 2, ilio-lumbar liga-
ment ; 3, anterior sacro-iliac ligament ; between 2 and 3, on the right side, the sacro-
vertebral ligament is shown, but not with sufficient distinctness ; 4, placed in the great
sacro-sciatic foramen, points to the lesser sacro-sciatic ligament ; 5, a portion of the great
sciatic ligament ; 6, the anterior ligament of the symphysis pubis ; 7, the obturator
membrane or ligament ; 8, the capsular ligament of the right hip-joint : the figure is
placed on its ilio-femoral band ; 9, the upper part of the divided capsular ligament of the
left hip-joint near the place of its attachment to the border of the acetabulum ; 10, placed
on the os pubis of the left side above the transverse ligament of the acetabular notch.
The head of the femur is withdrawn partially from the socket, so as to show the round
ligament stretched from the transverse ligament.
THE SACRO-SCIATIC LIGAMENTS. The posterior, or great sacro-sciatic liga-
ment, elongated, broad, and triangular, is placed at the inferior and poste-
rior part of the pelvis, whose lower aperture it assists in closing. Its base
or broader part is attached to the postero-inferior iliac spine and to the
side of the sacrum and coccyx ; whilst its other extremity is fixed along the
inner surface of the ischial tuberosity, where it expands somewhat, and
sends upwards and forwards along the margin of the ischial ramus a falci-
form process, the border of which is continuous with the obturator fascia,
forming the inferior attachment of that structure.
The anterior, or small sacro-sciatic ligament, much shorter and thinner
than the preceding one, in front of which it lies, is attached by its base
PUBIC ARTICULATION. 149
to the side of the sacrum and coccyx, where its fibres are blended with
those of the great ligament ; and, by its apex, to the spine of the ischium.
Its form is triangular, and the direction of its fibres is forwards and outwards.
Fig. 137.
Fig. 137. LIGAMENTS OP THE PELVIS AND HIP-JOINT, AS SEEN FROM BEHIND JN THE
ERECT ATTITUDE OF THE BODY, FROM A FEMALE SUBJECT.
1, ilio-lumbar ligament : above it the last lumbar intertransverse ligament ; 2, posterior
sacro-iliac ligaments, the short and the oblique ; 3, great sacro-sciatic ligament ; 4, attach-
ment of the lesser sacro-sciatic ligament to the spinous process ; 5, obturator membrane
or ligament ; 6, posterior ligament of symphysis pubis ; 7, 7, continuation of supraspinous
ligaments from the lower lumbar vertebrae over the sacral spines ; 8, transverse process
of last lumbar vertebra, to which from above is seen descending the last intertransverse
ligament, and from below ascending the sacro-vertebral ligament ; 9, posterior surface of
the capsular ligament of the hip-joint. The posterior ligaments passing between the
sacrum and coccyx are also partially shown,
Foramina. Between the upper border of the great sacro-sciatic liga-
ment and the innominate bone, is a large space subdivided by the small
sacro-sciatic ligament. The part which lies above this ligament is a large
oval opening, named the great sacro-sciatic foramen. It transmits the pyri-
form muscle, the great sciatic nerve, and the gluteal and ischiatic vessels
and nerves. The part between the greater and lesser sacro-sciatic liga-
ments, much smaller in size, and bounded in front by the smooth surface
between the spine and tuberosity of the ischium, is the small sacro-sciatic
foramen, through which pass the obturator iuternus muscle and the internal
pudic vessels and nerve.
The PUBIC ARTICULATION, or symphysis pubis, is the connection of the pubic
bones in front, and is effected by fibro-cartilaginous plates and ligaments.
The adjacent surfaces of bone are each coated with cartilage, and to this is
attached the fibro-cartilage which unites them. The fibro- cartilage is thicker
and stronger in front than behind, and generally contains a synovial cavity
towards the back part of the joint. The ligaments are named anterior,
posterior, superior, and inferior. The anterior pubic ligament consists
of irregular fibres passing obliquely across from bone to bone in front of the
150
ARTICULATIONS OF THE PELVIS.
syrcphysis. The superior and posterior ligaments consist of only a few fibres
on the upper and back part of the articulation. The inferior or subpubic liga-
ment, thick and triangular, is attached to the rami of the pubic bones, gives
Fig. 138.
Fig. 138. RIGHT HALF OP A FEMALE
PELVIS, SEEN FROM THE INNER SIDE.
AN OPENING HAS BEEN MADE INTO
THE ACETABULUM TO SHOW THE
TIGHTENED CONDITION OF THE ROUND
LIGAMENT WITH THE FEMUR PAR-
TIALLY FLEXED AND ADDUCTED. f
1, supraspinous ligaments descend-
ing to the sacrum from 2, 2, the
lumbar spinous processes ; 3, 4, the
lumbar and sacral spinal canal, with
its periosteal lining ; 5, placed on
the ilium above the anterior sacro-
iliac ligament ; 6, placed in the great
sacro- sciatic foramen, points to the
lesser sacro-sciatic ligament ; 7, greater
sacro-sciatic ligament, with 7', its
continuation over the inner border of
the tuberosity of the ischium ; 8, a
portion of the wall of the cotyloid
cavity, removed so as to give a view
from the inside of the head of the
femur, 9, with the round ligament
put upon the stretch, the femur
being partially flexed and ad ducted ;
10, the inner pait of the capsular
ligament relaxed ; 11, the shaft of
the femur.
smoothness and roundness to the upper part of the subpubic arch, and
forms part of the outlet of the pelvis.
The obturator membrane or ligament is a fibrous septum attached to the
border of the thyroid foramen, which it closes in its entire extent, except at
the upper and outer part of its circumference, where a small oval canal is
left for the obturator vessels and nerve. The membrane is fixed accurately
to the bony margin at the upper and outer sides of the foramen, and to the
posterior surface at the inner side. The obturator muscles are attached to
its surfaces.
MOVEMENTS. In ordinary circumstances there is very little movement allowed
between the bones of the pelvis. In the erect posture the sacrum is thrown so
much backwards, that none of the advantage of the key-stone of an arch is ob-
tained by the tapering of its form from base to apex. It is only by the sinuosities
of its auricular surfaces that it directly presses on the hip-bones ; and as the width of
the bene rather diminishes at the upper or ligamentous part, the principal strain
is borne by the posterior sacro-iliac ligaments, from which the sacrum is in great
measure suspended (see fig. 139) as is well illustrated by the giving way and
bending inwards and downwards of their iliac points of attachment in rickety
deformities of the pelvis. Thus the structure of the sacro-iliac articulation gives
elasticity. The small amount of movement which is allowed between the bones of the
pelvis in the ordinary state is increased during parturition in this way, that the lower
part of the sacrum being pressed backwards, the wider part of the edge formed by
this bone is forced farther between the ossa innominata, so as to separate them to a
greater degree, and thus to increase the capacity of the pelvis. In some subjects it
would appear that in pregnant women a slight amount of separation may occasionally
occur at the symphysis from the extreme looseness of the connecting parts ; but in
general it is more probable that the only motion at the symphysis is the hinge-like
movement of the ossa innominata just described, and that the cavity of the pelvis
THE HIP-JOINT.
151
owes the principal increase of its dimensions in parturition to the same cause. (See
Wood, article " Pelvis " in " Cyclopaed. of Anat. and Physiol ; " Zaglas, in " Monthly
Journ. of Med. Science," 1851 ; J. AL Duncan, in " Dublin Quart. Journ. of Med.
Science/' 1854, and " Edin. Med. Journ.," 1855 ; Struthers, " Anat. Observ.")
ARTICULATIONS OF THE LOWER LIMB.
THE HIP- JOINT.
This is a large ball-and-socket joint, in which the globular head of the
femur is received into the acetabulum or cotyloid cavity of the innominate
Fig. 139.
Fig. 139. TRANSVERSE OBLIQUE SECTION OP THE PELVIS AND HIP-JOINT, CUTTING TIJK
FIRST SACRAL VERTEBRA AND THE SYMPHYSIS PUBIS IN THEIR MIDDLE, FROM A MALK
SUBJECT OF ABOUT NINETEEN YEARS OF AGE.
1, placed above the middle of the cut surface of the first sacral vertebra, and between
the divided superior articular processes ; 2, the divided ilium ; 3, the posterior sacro-
iliac ligaments also divided ; 4, 4, the sacro-iliac synchondrosis, with a slight separation
between the two plates of cartilage ; 5, the anterior sacro-iliac ligament; 6, the anterior
or short sacro-sciatic ligament ; 7, a portion of the posterior or long sacro-sciatic ligament ;
8, placed in front of the symphysis pubis, in the cut surface of which the small median
cavity, the adjacent fibro-cartilaginous plates and the anterior and posterior ligamentous
fibres are shown; .9, the lower part of the obturator membrane; 10, placed on the
cartilaginous surface of the cotyloid cavity of the right side, through the middle of which
the incision passes transversely and divides the round ligament and the synovial fat of
the depression; 11, the cotyloid ligament or fibrous border; 12, the round ligament of
the left side, where it is connected with the transverse part of the cotyloid ligament ;
13, placed on the cut surface of the head of the left femur near the depression where the
round ligament is attached ; 14, 14', the upper and lower parts of the capsular ligament
and synovial capsule.
152 ARTICULATIONS OF THE LOWER LIMB.
bone. The articulating surface of the acetabuluin is formed by a broad
riband-shaped cartilage occupying the upper and outer part, and folded
round a depression which, extending from the notch, is hollowed out in the
bottom of the cavity, and is occupied by delicate adipose tissue covered
with synovial membrane, the so-called synovial or Haversian gland. The
articulating surface of the femur presents a little beneath its centre a pit in
which the round ligament is attached.
The cotyloid ligament forms a thick ring round the margin of the aceta-
bulum, increasing the depth of its cavity, and bridging over the deficiency in
its border. Its external surface is in contact with the capsular ligament, the
internal closely embraces the head of the femur, and both are covered by
the synovial membrane. Its fibres do not run parallel to the circumference
of the cotyloid cavity, but pass obliquely from without inwards over its
margin, one extremity being attached to the outer, the other to the inner
surface.
At the cotyloid notch the fibres of the ligament are continued from side
to side, so as to render the circumference complete, aud deeper transverse
fibres are superadded, from which circumstance, as well as from being
stretched across from one margin of the notch to the other, this part is
called the transverse ligament. Subjacent to it an interval is left for the
admission of the articular vessels.
The interarticular or round ligament (ligamenturn teres) is a strong fasci-
culus surrounded by synovial membrane, implanted by one extremity, which
is round, into the fossa in the head of the femur ; by the other, which is
broad, flat, and bifid, into the margins of the cotyloid notch, where its
fibres become blended with those of the transverse ligament. It rests on
the fat in the depression of the acetabulum.
The capsular ligament, surrounding the joint, is attached superiorly in
the greater part of its extent to the acetabulum, within two or three lines
from the cotyloid ligament, except at the notch, where it is connected with
the transverse ligament. At its femoral border it extends in front as far
as the anterior intertrochanteric line, but behind it falls short considerably of
the posterior intertrochanteric ridge. Its strongest part is in front, and there
its fibres extend vertically from the upper part of the acetabulum to the lower
part of the intertrochanteric line, and are strengthened by a firm fasciculus,
descending from the anterior inferior spine of the ilium, called the accessory
or ilio-femoral ligament. On its superior border the capsule is strengthened
by fibres connected with the insertion of the gluteus minimus muscle. The
fibres which arise in front of the notch of the acetabulum pass down in
front of the small trochanter; those which arise behind the notch pass
towards the trochanteric fossa ; and between those two fasciculi, the capsule
is extremely weak, and its fibres pass in a circular direction, so that oppo-
site the posterior intertrochanteric ridge no fibres are inserted into the neck
of the femur, and the reflection of the synovial membrane from the bone to
the capsule can be laid bare behind the neck without cutting any part of the
capsule.
The synovial membrane lining the joint and ligament is reflected from the
neck of the femur to the inner surface of the capsule ; passing over the inner
surface of the capsule to the margin of the acetabulum, it is reflected from
that and from the synovial fat as a tubular investment of the round
ligament to the head of the femur.
MOVEMENTS. In the hip-joint movement is allowed in every direction. Extension
is limited by the capsular ligament, the anterior fibres of which become tense in that
THE KNEE-JOINT.
153
position : flexion is limited only by the contact of the neck of the femur with the
acetabulum. The round ligament is put upon the stretch when the thigh is partially
flexed and adducted; it therefore resists dislocation upwards and backwards on
the dorsum ilii, which is, notwithstanding its presence, the most frequent kind of
displacement. The round ligament is also put upon the stretch in the position of
flexion and external rotation.
THE KNEE-JOINT.
The articular surfaces of this .complicated joint are the condyles of the
femur and tibia, with fibro- cartilages interposed, the articulating surface of
the patella, and the patellar surface of the femur. The action is mainly that
of a hinge-joint. The joint is strengthened superficially by fibrous coverings
Fig. 140.
Fig. 140, A. RIGHT KNEE-JOINT, FROM THE INSIDE AND ANTERIORLY. J
1, tendon of the rectus muscle near its insertion into the patella ; 2, insertion of the
vastus internus into the rectus tendon and side of the patella ; 3, ligamentum patellae
descending to the anterior tuberosity of the tibia ; 4, capsular fibres forming a lateral
ligament of the patella prolonged in part from the insertion of the vastus internus down-
wards towards the inner tuberosity of the tibia ; 5, internal lateral ligament of the knee-
joiut seen spreading on the internal semilunar cartilage ; 6, tendon of the semimembranosus
muscle (after Arnold).
Fig. 140, B. KNEE-JOINT FROM BEHIND.
1, insertion of the tendon of adductor magnus ; 2, origin of the inner head of the
gastrocnemius muscle ; 3, outer head of the same ; 4, cord-like external lateral ligament ;
5, tendon of the popliteus muscle : a ligament descending from behind the outer condyle
of the femur is seen attached to this tendon below, and another descending from the
tendon is attached to the head of the fibula, constituting the short external lateral liga-
ment ; 6, part of internal lateral ligament ; 7, tendon of the semimembranosus muscle ;
8, posterior ligament of Winslow, spreading outwards from the tendon ; 9, expansion of
the popliteal fascia downwards from the same, represented as cut short; 10, on the head
of fibula, marks the posterior superior tibio-fibular ligament; 11, upper part of the
interosseous ligament, with the foramen above it for the anterior tibial artery.
154
ARTICULATIONS OF THE LOWER LIMB.
derived from the muscular tendons and aponeuroses. The ligaments which
have received special names are the following.
The internal lateral ligament, long and flat, connects the internal
tuberosity of the femur with the inner tuberosity and the hinder border
of the tibia, on the shaft of which it descends for some distance. Superiorly
its deep surface rests on the articular synovial membrane ; in the middle it
is attached to the internal seinilunar cartilage ; and below the head of the
tibia the anterior slip of insertion of the semimembranosus muscle passes
between the ligament and the bone.
The external lateral ligament is a rounded cord, which extends from the
external tuberosity of the femur to the head of the fibula. Its internal
surface corresponds with the tendon of the popliteus muscle and the inferior
Fig. 141.
Fig. 141, A. THE KNEE-JOINT, OPENED FROM BEFORE; THE PATELLA, CAPSULE, AVD
SYNOVIAL STRUCTURES REMOVED, TO SHOW THE CRUCIAL LIGAMENTS AND SEMILUNAR
CARTILAGES, 3
1, external, and 2, internal semilunar cartilage ; 3, on the outer condyloid surface of
the femur, points to the anterior external crucial ligament ; 4, placed on the elevated line
separating the patellar from the inner condyloid surface of the femur, points to the
posterior or internal crucial ligament ; 5, transverse ligament of the semilunar cartilages ;
6, part of the ligamentum patellae ; 7, on the head of the fibula, points to the superior
anterior tibio-fibular ligament ; 8, upper part of the interosseous membrane, showing the
perforation for the anterior tibial artery.
Fig. 141, B. THE KNEE-JOINT, OPENED FROM BEHIND, AND ITS STRUCTURES REMOVED,
SO AS TO EXPOSE THE CRUCIAL LIGAMENTS AND SEMILUNAR CARTILAGES.
1, posterior part of the internal semilunar cartilage ; 2, external semilunar cartilage ;
3, upper part of the external or anterior crucial ligament ; 4, lower part of the internal
or posterior crucial ligament : farther up is seen its accessory band joining the external
semilunar cartilage ; 8, upper part of the interosseous membrane ; 9, back part of the
internal lateral ligament; 10, placed on the head of the .fibula, points to the posterior
superior tibio-fibular ligament : between the head of the fibula and the external semilunar
cartilage (2) is seen the synovial surface of the tibia, upon which the semilunar cartilage
descends in flexion, and where a communication sometimes takes place between the
synovial cavities of the knee-joitit and the tibio-fibular articulation.
THE KXEE-JOIXT. 155
external articular vessels. The tendon of the biceps flexor cruris muscle
is frequently divided into two by this ligament, and between the ligament
and the tendon there is a synovial bursa. Further back is another baud,
the short external lateral ligament, the arrangement of which is more variable,
often connected with the tendon of the popliteus muscle, and occasionally
terminating in the capsular membrane.
The posterior ligament is a flat fasciculus of fibres passing from behind
the inner tuberosity of the tibia upwards and outwards to the external
condyle of the femur, and is in part continuous at its inner end with the
tendon of the semimembrauosus muscle.
The ligamentum patella is a strong flat band, of a tendinous nature,
attached superiorly to the lower extremity of the patella, and the
depression beneath its articular surface, and inferiorly to the anterior
tubercle of the tibia. Between the tibia and the ligament, near its insertion,
is placed a synovial bursa. If the patella be considered a sesamoid bone, this
ligament may be regarded as part of the tendon of the rectus femoris muscle.
The crucial ligaments, placed in the centre of the joint, pass from the
sides of the intercondyloid fossa to the spaces in front of and behind the spine
of the tibia. They decussate somewhat like the lines of the letter X. The
anterior or external ligament is fixed by its lower extremity to the inner
part of the pit before the spine of the tibia, and by its upper extremity it
is inserted into the inner and hinder part of the external condyle of the
femur ; hence its direction is upwards, backwards, and outwards. The
posterior or internal ligament is attached inferiorly to the back of the pit
behind the tibial spine, and superiorly to the fore part of the intercondyloid
hollow, as well as slightly to the side of the inner condyle of the femur ; its
fibres are directed upwards and a little forwards.
The semilunar cartilages are two crescent-shaped iuterarticular fibro-
cartilages, placed on the articulating surfaces of the head of the tibia, and
interposed between these and the condyles of the femur. They have each a
synovial surface above and below, and a convex border, which is thick,
while the concave border is thinned to a fine edge, and the part of the
articular surface of the tibia within the concave border of each cartilage is
left uncovered. At their extremities they are fibrous, and are firmly fixed
to the head of the tibia, whilst by the circumference they are connected
with the fibrous capsule of the joint.
Fig. 142. VIEW OP THE INTERARTICULAR FIBRO- Fig. 142.
CARTILAGES OP THE RIGHT KNEE-JOINT, PROM
ABOVE, AS THEY LIE ON THE UPPER SURFACE
OP THE TlBIA, WITH THE CRUCIAL LlGAMENTS
DIVIDED, AND THE LlGAMENTUM PATELL.E TURNED
FORWARDS. ^
1, ligamentum patellae ; 2, the inner, or semicircular
fibre -cartilage ; 3, the outer, or nearly circular one ;
4, is placed above the anterior tuberosity of the tibia
in front of the transverse ligament ; 5, the cut end
of the anterior crucial ligament directed obliquely
towards the outer side and backwards; 6, the cut
end of the posterior crucial ligament, from which fibres are seen descending to the outer
fibro-cartilage ; b'', tibial attachment of the posterior crucial ligament; 7, the head of
the fibula; 8, the synovial surface of the tibia, which extends for some way downwards
towards the tibio-fibular synovial sac, with which it is sometimes continuous.
The internal semilunar cartilage, elongated from before backwards, is
nearly of a semicircular form: its anterior cornu is small and pointed, and
is inserted into an impression at the fore and outer part of the internal
156
ARTICULATIONS OF THE LOWER LIMB.
articular surface of the tibia; its posterior end is attached to the inner
edge of the hollow behind the spine, and is in relation with the posterior
crucial ligament.
The external semilunar cartilage forms nearly a complete circle ; its two
cornua, fixed, one before, the other between the points of the spine of the
tibia, are so close at their insertion that they may be said to be interposed
between the attachments of the internal semilunar plate. Its external
border is in contact behind with the tendon of the popliteus muscle, and is
therefore separated by this from the fibrous capsule. From this fibro-
cartilage a ligamentous band ascends, to be attached to the inner condyle of
the femur in connection either in front or behind with the posterior crucial
ligament (accessory band of the posterior crucial ligament).
Transverse ligament. Towards the front of the joint the convex borders
of the interarticular fibro- cartilages are connected by a slight transverse
band, which receives this name. Its thickness varies much in different
bodies.
Capsular membrane. Under this name is described the fibrous tissue
which invests the joint in the intervals between the stronger bands which
have been named ligaments. It is incomplete, not extending underneath
the tendons of the extensor muscles. Between the sides of the patella and
the femur it consists of fibres connected with the insertion of the vasti
muscles and with the fascia lata, and thus forms the structures, uniting the
patella to the tibia, which have been called lateral patellar ligaments ;
posteriorly it covers the condyles of the
Fig- 143. femur beneath the gastrocnemius muscle.
In this last situation it is thin, and a
sesamoid bone is often found in connection
with it in the outer, less frequently in the
inner head of the muscle.
Fig. 143. VERTICAL ANTERO-POSTERIOB SECTION
OF THE LEFT KNEE-JOINT, SEEN FROM THE
OUTER OR LEFT SIDE. ^
The section is made somewhat obliquely a little
to the outside of the middle, so as to preserve entire
the crucial ligaments with their attachments : it is
from a young subject of eighteen or nineteen years.
1, 1, the upper portion of the synovial cavity of
the joint, showing in the part above the patella the
synovial pouch which extends upwards between the
extensor tendons and the femur ; 1', an aperture
made into the posterior portion of the synovial
cavity ; 2, 2', ligamentum mucosum ; 3, ligamen-
tum patellae ; 2', 3, the subpatellar synovial fatty
cushion ; 4, bursa above the insertion of the liga-
mentum patellae into the anterior tibial tuberosity ;
5, 5', the anterior crucial ligament ; 5', points also
to the internal semilunar cartilage within the joint;
6, lower part of the posterior crucial ligament, the
upper part of which is towards 2 ; 6', the accessory
band joining the external semiluuar cartilage,
which is cut short ; 7, the spine of the tibia.
The synovial membrane is the largest in
the body. Traced downwards from the
femur on either side of the joint, it may
be followed from the capsule to the upper surface of the semi-lunar
cartilages, round the free borders of those structures to their inferior surfaces
THE KNEE-JOINT.
157
and thence to the tibia. The crucial ligaments are invested in front by a
reflected portion of the membrane continued forwards from the posterior
wall of the joint. Between the tibia and patella the synovial membrane
lies upon a large pad or cushion of fat, on the surface of which it forms two
lateral folds (alar ligaments) which fit into the space between the tibia,
patella and femur, while from the middle of the pad it sends backwards a
tapering process, the ligamentum mucosum, through the joint to the front
of the intercondyloid fossa. Above the patella the synovial membrane
extends upwards some distance, forming a large pouch between the extensor
tendons and the femur.
MOVEMENTS, &c. In order to explain the nature of the movements, it is neces-
sary to state some considerations with regard to the relations of the several parts of
the knee-joint to each other. The knee-joint may be regarded as consisting of
three articulations conjoined, viz., that between the patella and femur, and two others,
one between each condyle of the femur and the tibia. In most mammals the synovial
membranes of those three joints are either completely distinct or communicate with
each other by only small openings. In the human subject the ligamentum mucosum
is an indication of the original distinctness of the synovial membranes of the inner
and outer joints, and the crucial ligaments may be looked upon as the external and
internal lateral ligaments of those two joints respectively. Each portion of the
articular surface of the femur belongs either to one or other of the three component
joints of the knee, and no part is common to any two of them-. On a well-marked
Fig. Hi.
Fig. 144. THE SUPERFICIAL PARTS OF THE KNEE-JOINT REMOVED, AND THE EXTERNAL
CONDYLE OF THE FEMUR SAWN OFF OBLIQUELY, TOGETHER WITH HALF THE PATELLA,
SO AS TO EXPOSE BOTH THE CRUCIAL LIGAMENTS TOGETHER. J
lu A, the parts are in the position of extension, in B, that of flexion, the figures being
designed to show the different state of tension of the crucial ligaments in these positions.
1, sawn surface of the femur ; 2, sawn surface of the patella; 3, ligamentum patellae;
4, anterior or external crucial ligament, tense in A, and relaxed in B ; 5, posterior or
internal crucial ligament, relaxed in A, tense in B ; 6, internal, and 7, external semilunar
cartilage ; 8, transverse ligament ; 9, articular surface of the tibia, extending behind the
external semilunar cartilage ; 10, on the head of the fibula, points to the anterior superior
tibio-peroneal ligament ; 11, upper part of the interosseous membrane.
158 ARTICULATIONS OF THE LOWER LIMB.
femur, the inferior limits of the patellar surface are quite distinguishable ; the line
which separates this surface from the outer tibial joint passing directly between it
and the condyle, and that which separates it from the inner joint being continued
backwards, so as to cut off from the rest of the inner condyle a narrow tract at the
side of the intercondyloid fossa.
The movement of the patella on the femur is one partly of gliding, partly of
coaptation. This is illustrated by a careful examination of the articular surface of
the patella, which is not uniformly curved from above downwards, as it would be,
were the movement one of gliding only, but exhibits on each side of the vertical ridge
three very slightly depressed surfaces, separated by two slight transverse elevations,
and along the inner margin a seventh area, upon which the transverse lines do not
encroach (Goodsir). When the knee is extended, and the patella drawn upwards by
the extensor muscles, the two inferior facets of the patella are in contact with the
upper margin of the femoral surface ; in semiflexion the middle facets only are in
contact with the femur; in greater flexion, the superior parts of the patella are
in contact with the lower part of the femoral surface; and in extreme flexion the
patella, which has been gradually turned outwards by the increasing prominence of
the inner condyle, rests by its innermost facet on the intercondyloid margin of that
condyle. If the condyles of the femur be examined as they rest upon the tibia in the
flexed position of the joint, it will be seen that the inner condyle is more elongated
than the outer, and that the portion of the inner condyle which lies in front of the
anterior limit of the external condyle inclines obliquely outwards, to reach the patellar
surface. In the movement of extension the condyles move parallel to one another,
until complete extension is nearly reached, and then, the anterior part of the
rolling surface of the external condyle having already come into contact with the tibia,
the inner condyle continues to glide backwards, and brings its oblique anterior part
into contact with the tibia, so that the bone is rotated inwards on the tibia, and
over-extension is prevented, not merely by the tightness of the ligaments, but by
the femur being pressed up against the tibial spine. In complete extension the lateral
ligaments and the external crucial ligament are tight, while the posterior crucial
ligament is relaxed; in flexion the external and internal lateral and the external crucial
ligaments become relaxed, and the posterior crucial ligament is tightened. In exten-
sion of the joint no rotation of the leg is possible ; in the flexed condition a consider-
able amount is allowed. When the weight of the body keeps the bones in their position
in the extended knee, the extensor muscles are relaxed, the patella drops down from
its position in contact with the femur, and the ligamentum mucosum then comes into
play, supporting the synovial membrane and fat below the patella. (See Meyer, op.
cit. ; Goodsir, in " Edin. Med. Journ.," 1855, and" Proceedings of Roy. Soc. of Edin."
1858; Langer, " Sitzungsber. d. Acad. der Wissensch. Wien,"1858; Henke, "Zeitschr.
fUr rat. Med.," v. viii., 1859.)
ARTICULATIONS OF THE LEG AND ANKLE.
PERONEO-TIBIAL ARTICULATIONS. The tibia and fibula are connected at
their tipper and lower extremities by synovial articulation, and their shafts
are united by an interosseous membrane.
The superior extremities of the bones present two flat oval articular surfaces,
retained in close contact by an anterior and a posterior superior tibio-fibular
ligament, both of which pass upwards and inwards from the head of the fibula
to the external tuberosity of the tibia. The synovial membrane which lines
this joint not unfrequently communicates posteriorly with that of the knee.
The interosseous membrane or ligament, which connects the shafts of the
tibia and fibula, passes between the external ridge of the tibia and the
ridge on the inner surface of the fibula, and is composed for the most part
of parallel fibres running outwards and downwards, only a few fibres crossing
them in a different direction. The membrane is broader above tban below,
and presents superiorly an elongated opening for the transmission of the
anterior tibial vessels, and inferiorly a small aperture for the passage of the
anterior branches of the peroneal vessels.
THE ANKLE-JOINT.
159
The inferior extremities of the tibia and fibula are in contact by surfaces
which -for the most part are rough and bound together by ligament, but near
Fig. 145. ARTICULATIONS OP THE KNEE, LEG AND ANKLE, SEEN Fi S- 145 -
FROM BEFORE. | / ,
1, superior anterior tibio-fibular ligament ; 2, interosseous mem-
brane; 3, points to the anterior inferior tibio-fibular ligament; 4,
internal lateral ligament of the ankle-joint ; 5, middle vertical part
(calcaneo-fibular) of the external lateral ligament of the ankle-joint ;
6, anterior part (talo-fibular) of the same ; 7, anterior ligament of
the ankle-joint.
their lower edges are smooth and covered by cartilage. The
tibial surface is concave, the fibular convex ; but the lower
edges of both surfaces are straight. The strong short
fibres which pass directly between the opposing surfaces
form the inferior interosseous ligament. The anterior liga-
ment is a flat band of fibres, extended obliquely over the
lower part of the bones, the direction of its fibres being
downwards from the tibia to the fibula. The posterior liga-
ment, somewhat triangular, is similarly disposed behind the
articulation ; its outer surface is covered by the peronei
muscles. The transverse ligament, longer and narrower
than the preceding, is placed immediately below it ; its
fibres are horizontal, and extend from the external
malleolus to the contiguous part and hinder border of the
articular surface of the tibia ; it closes the interval
between the bones.
The synovial cavity lying between the small articular
surfaces is an extension of that of the ankle-joint.
THE ANKLE-JOINT. In this articulation, which is a
hinge-joint, the inferior extremities of the tibia and
fibula, united so as to form a kind of arch, embrace
transversely the superior articular surface of the astragalus,
so as to render lateral movement impossible when the ligaments are tense.
Fig. 146.
Fig. 146. THE LOWER TIBIO-FIBULAR ARTICULATION AND
ANKLE-JOINT, FROM BEHIND.
1, inferior posterior tibio-fibular ligament; 2, transverse
ligament ; 3, posterior fibres of the internal lateral ligament
of the ankle-joint ; 4, middle, and 5, posterior part of the
external lateral ligament of the aukle-joint ; 6, posterior
talo-calcaneal ligament.
The internal lateral ligament is a flat fasciculus
of fibres, much broader at the lower than at the
upper part. One extremity is attached to the
inferior border of the internal malleolus; the other,
to the inner side of the astragalus, the os calcis,
and the scaphoid bone, as well as to the inferior
calcaneo-scaphoid ligament.
The external lateral ligament consists of three distinct bands, separated by
intervals and disposed in different directions. 1. The middle band descends
from the extremity of the fibula, and is inserted into the middle of the
external surface of the os calcis. 2. The anterior band passes obliquely
160 ARTICULATIONS OF THE LOWER LIMB.
forwards and inwards from the fore part of the outer malleolus to a part of
the astragalus in front of its external malleolar surface ; it is the shortest
of the three. 3. The posterior band, the strongest of the three, passes
almost horizontally inwards from the pit on the inner and back part of the
malleolus to the posterior surface of the astragalus.
Fig. 147. TRANSVERSE- VERTICAL SECTION OP THE RIGHT
Fig. 147. ANKLE-JOINT NEAR ITS MIDDLE, AND OF THE POSTERIOR
TALO-CALCANEAL ARTICULATION, so AS TO SHOW THE
SHAPE OP THE ARTICULAR SURFACES AND CAVITIES,
VIEWED FROM BEFORE. ^
1, internal, 2, external malleolus ; 3, placed on the astra-
galus at the angle between its superior and its external
raalleolar surfaces ; 4, points to the interosseous tibio-fibular
ligament ; 5, internal lateral ligament of the ankle-joint ;
6, sustentaculum tali ; 7, calcaneo-fibular or middle part of
the external lateral ligament ; 8, inner part of the inter-
osseous calcaneo-talar ligament ; 9, great tuberosity of the
calcaneum : between the tibia, fibula and astragalus, the
synovial cavity is indicated by the dark space enclosed by a
white line ; between the astragalus and os calcis a section of
the posterior calcaneo-talar synovial cavity is shown.
The anterior and posterior ligaments are merely
scattered fibres in front of and behind the joint ;
those of the posterior ligament are weak and
principally transverse.
The synovial membrane of the ankle-joint extends upwards by a small
process which lines the inferior peroneo-tibial articulation.
MOVEMENTS. The movements at the ankle-joint are mainly those of flexion and
extension of the foot, and the directions of those movements are principally determined
by the shape of the articular surfaces. The external border of the superior cartila-
ginous surface of the astragalus is curved, and longer than the internal border, and
hence extension of the ankle-joint is accompanied with a slight inward movement
of the toes. The horizontal surfaces of both the tibia and astragalus are broader in
front than behind ; hence in complete extension of the ankle the narrow part of the
astragalus is brought into the widest part of the space between the malleoli, and a
certain amount of lateral motion is allowed, whereas in complete flexion, as when the
weight of the body, with completely bended knees, is supported on the toes, the broad
part of the surface of the astragalus is pushed back into the narrowest part of the
space, and the inferior extremity of the fibula is pressed upon, so as to stretch the
ligaments between it and the tibia, and give a certain amount of spring to the joint.
There appears to be no other movement between the tibia and fibula ; these bones
being bound together at their lower ends with remarkable firmness.
ARTICULATIONS OF THE FOOT.
ARTICULATIONS OF THE CALCANEUM, ASTRAGALUS, AND SCAPHOID BONES
ONE WITH ANOTHER. The astragalus is connected with the calcaneum by two
synovial articulations, viz., by a posterior one peculiar to those two bones,
and by an anterior one common to them with the scaphoid bone. The fol-
lowing are the principal parts requiring description.
Astragalo-calcaneal ligaments. The interosseous ligament, broad and
strong, passes vertically downwards from the groove between the anterior
and posterior articular surfaces of the astragalus to the similar groove between
the corresponding articular surfaces of the calcaneum. A membranous
posterior ligament connects the posterior border of the astragalus with the
upper surface of the calcaneam ; its fibres are oblique and very short.
TARSAL ARTICULATIONS.
161
There is also an external ligament, consisting of a slight fasciculus of fibres,
which descends perpendicularly from the outer surface of the astragalus
to the external side of the calcaneum, parallel with the middle division
of the external lateral ligament of the ankle-joint. It may be farther
observed, that those portions of the lateral ligaments of the ankle-joint
which pass down over the astragalus to the os calcis assist in uniting
these two bones.
Calcaneo-scaphoid ligaments. The calcaneum and scaphoid bone are not in
contact, but they are connected by two ligaments. The inferior or plantar
ligament, much the larger of the two, is a broad baud which passes forwards
and inwards from the fore-part of the calcaneum (sustentaculum tali) to the
inferior surface of the scaphoid bone. It is in contact inferiorly with the
tendon of the tibialis posticus muscle, while superiorly it forms the floor of
the articular cavity which receives the head of the astragalus, and is lined
by synovial membrane. The external, dorsal, or interosseous ligament,
forms the external boundary of the cavity just mentioned, and lies deeply
at the anterior part of the fossa (sinus pedis), between the astragalus and
os calcis. Its fibres, very short, are directed from behind forwards between
the contiguous extremities of the bones. They are attached posteriorly
to a ridge of the os calcis that separates the articular surfaces for the
astragalus and os cuboides, and anteriorly to
the outer side of the scaphoid bone.
Fig. 148. LIGAMENTS OP THE FOOT, SEEN FROM
BELOW. g
1 and 2, portions of the internal lateral ligament
of the ankle-joint descending upon the calcaneum ;
3, calcaneo -cuboid or long plantar ligament ; 3', deep
or short part of the same ; 4, plantar calcaneo-sca-
phoid ligament ; 5, three scaphoido-cuneifonn liga-
ments of the internal, middle and external cuneiform
bones ; 6, is placed upon the external cuneiform bone,
towards which is seen coming from behind a cuboido-
cuneiform ligament ; 7, is placed upon the internal
cuneiform bone ; from 6 and 7, are seen passing down-
wards the plantar cuneo-metatarsal ligaments; x , part
of the first dorsal cuneo-metatarsal ligament; 8 and 9,
ligamentous fibres prolonged from the cuboid bone
and sheath of the peroneus longus muscle upon the
outer metatarsal bones ; 10, 10, between these figures
the posterior intermetatarsal (or transverse) ligaments ;
11, 11, anterior transverse metatarsal ligament, con-
tinued across the four metatarsal spaces ; 12, inter-
sesamoid ligament ; 13, 13, between these figures are
seen the five pairs of internal and external lateral
metatarso-digital ligaments; 14, 14, between these
figures are seen the five pairs of internal and external
lateral digital (phalangeal) ligaments of the first
series ; those of the second series have no figure placed
to mark them ; 15, inferior ligament of the phalangeal
articulation of the great toe.
u
The talo-scaplioid or astragalo-scapJioid liga-
ment, a membranous band of fibres situated
on the dorsuin of the foot, extends obliquely forwards from the anterior
extremity of the astragalus to the superior surface of the scaphoid bone,
and completes the capsule of the calcaneo-talo-scaphoid joint, formed in the
rest of its extent by the plantar and external calcaueo-scaphoid ligaments.
162
ARTICULATIONS OF THE LOWER LIMB.
One synovial membrane lines the calcaneo-talar joint, and another the
calcaneo-talo- scaphoid articulation.
CALCANEO-CTJBOID ARTICULATION. The calcaneum is united to the
cuboid bone by a synovial joint and ligaments.
The inferior ligament consists of two distinct fasciculi of fibres, differing
in form and attachments ; of which one is superficial, the other deep-seated.
The superficial part, called the long plantar ligament, is the longest of the
tarsal ligaments. Its fibres, attached behind to the inferior surface of the
calcaneum as far as the anterior tubercle, pass forwards, and are attached in
greater part to the tuberosity on the under surface of the cuboid bone ;
some of them are continued onwards, and terminate at the bases of the
third and fourth metatarsal bones, after covering the tendon of the peroneus
longus muscle. The short or deep-seated plantar calcaneo-cuboid ligament
lies close to the bones, being separated from the superficial part by some
cellular tissue. Its breadth is considerable, its length scarcely an inch.
One extremity is attached to the calcaneum in front of the long ligament,
the other (somewhat expanded) to the under surface of the cuboid bone,
internal to the tuberosity.
The dorsal or superior ligament is a flat band of fibres which connects the
anterior and upper surface of the calcaueum with the adjacent part of the
cuboid bone.
The internal or interosseous ligament is placed deeply in the hollow
between the astragalus and os calcia, and is closely connected with the
external calcaneo-scaphoid ligament.
Fig. 140.
Fig. 149. LIGAMENTS OF THE FOOT, FROM THE INNER SIDE. ^
1, internal lateral ligament of the ankle ; x , in front of the sustentaculum tali, showing
part of the internal lateral ligament descending upon it ; 2, posterior talo-calcaneal liga-
ment ; 3, posterior ligament of the ankle-joint ; 4, part of the long and short calcaneo-
cuboid ligaments seen from the inside ; 5, two superior astragalo-scaphoid or talo-scaphoid
ligaments ; 6, internal talo-scaphoid ligament ; 7, internal scaphoido-cuneiform (first) ;
8, dorsal or superior cuneiform ; 9, scaphoido-cuneiform (second) ; 10, intercuneiform, or
transverse dorsal cuneiform, between the first and second cuneiform bones; 11, internal
or first tarso-metatarsal ligament ; 12, inferior first tarso-metatarsal ; 13, internal lateral
metatarso-digital : the internal sesamoid bone is seen below; 14, internal lateral digital
ligament (of the first toe) : those of the second toe are also seen beyond.
TARSAL ARTICULATIONS. 163
A separate synovial membrane lines this joint.
ARTICULATIONS OF THE SCAPHOID, CUBOID, AND CUNEIFORM BONES, ONE
WITH ANOTHER. The scaphoid and cuboid bones are connected by a dorsal
ligament, composed of short thin fibres, extended obliquely between the
two bones ; a plantar, situated in the sole of the foot, and consisting of
transverse fibres ; and an interosseous ligament, which intervenes between
the bones, and is attached to their contiguous surfaces. When the bones
touch, which is not always the case, they present two small articulating sur-
faces, which are covered with cartilage, and have between them an offset
of the adjacent synovial membrane.
The scaphoid and the cuneiform bones are held together by dorsal liga-
ments. It will be recollected that the scaphoid bone articulates with the
three cuneiform by the smooth faces on its anterior surface. The dorsal
ligaments, three in number, pass from the upper surface of the scaphoid to
the first, second, and third cuneiform bones, into which they are inserted.
Plantar bands are similarly disposed on the under surface of the bones, but
these are continuous with, or offsets from, the tendoa of the tibialis
posticus muscle.
The cuboid and the external cuneiform bones are connected by a dorsal
Fig. 150.
21 '22.
Fig. 150. LIGAMENTS OK THE FOOT, FEOM THE OUTSIDE AND DORSAL ASPECT. 3
1, lower part of the interosseous membrane; 2, lower anterior tibio-peroneal ligament;
3, lower posterior tibio-peroneal ligament; 4, middle part of the external lateral
ligament of the ankle-joint, passing to the calcaneum ; 5, anterior part of the external
lateral ligament of the ankle-joint, passing to the astragalus ; below the last ligament
the external calcaneo-talar ligament has not been represented in this figure ; 6, posterior
part of the external lateral ligament of the ankle-joint, passing to the astragalus ;
7, is placed above the interosseous calcaneo-talar ligament ; 8, dorsal calcaneo -scaphoid ;
9, dorsal calcaneo-cuboid ; 10, part of the long plantar or calcaneo- cuboid ; 11, superior
talo-scaphoid ; 12 and 13, second and third scaphoido-cuneiform, and between them one
of the intercuneiform ligaments ; 14, superior scaphoido-cuboid ; 15, placed on the
external cuneiform bone, points to the cuneo-metatarsal ligament of the third bone ; above
and below 15, are corresponding ligaments from the external cuneiform to the second
and fourth metatarsal bones ; 16, cuneo-metatarsal ligament, from the first cuneiform to
the second metatarsal bone; between 12, and 16, are seen the cuneo-metatarsal ligaments
which converge from the three cuneiform bones on the second metatarsal; 17, cuboido-meta-
tarsal ligament passing to the fourth metatarsal bone; 18, that to the fifth ; 19 and x x ,
dorsal intermetatarsal ligaments ; 20, lateral metatarso-digital ; 21, 22, lateral digital.
164 ARTICULATIONS OF THE LOWEE LIMB.
ligament, which, is a thin fasciculus of fibres extended between them ;
a plantar ligament, whose fibres are transverse and rather indistinct ; and a
bundle of interosseous fibres attached to their neighbouring sides. Between
the two bones a distinct articulation is formed by cartilaginous surfaces ; it is
provided sometimes with a separate synovial membrane, at others with an
offset from that which belongs to the scaphoid and cuneiform bones.
The three cuneiform bones are connected by transverse dorsal ligaments
and strong interosseous fibres ; but the latter are their most efficient uniting
structures. A transverse plantar ligament exists only between the two
innermost bones. The articulations between these bones are lined by offsets
from the synovial membrane of the joint between them and the scaphoid
bone.
ARTICULATION OF THE TARSUS WITH THE METATARSUS. The four anterior
bones of the tarsus, viz., the three cuneiform and the cuboid, articulate
with the metatarsal bones ; and as the first and third cuneiform bones pro-
ject beyond the middle one, and the third cuneiform beyond the cuboid
bone, the anterior surface of the tarsus is very irregular. The first meta-
tarsal bone articulates with the internal cuneiform ; the second is wedged
in between the first and third cuneiform, and rests against the second ; the
Fig. 151.
Fig. 151. THE SYNOVIAL CAVITIES OF THE ANKLE-JOINT AND THE TARSAL AND
TARSO-METATARSAL ARTICULATIONS, IN SECTION.
The section has been carried obliquely upwards and inwards across the foot, and
vertically through the upper part of the astragalus and the tibia. 1, cut surface of tbe
tibia above the ankle-joint ; 2, placed on the astragalus above the posterior calcaneo-talar
synovial cavity ; 3, on the head of the astragalus close to the common calcaneo-talo-
scaphoid synovial cavity ; 4, interosseous calcaneo-talar ligament; 5, on the anterior edge
of the calcaneum, points to the calcaneo-cuboid synovial cavity ; 6, interosseous calcaneo-
cuboid ligament ; 7, on the scaphoid bone, marks the common scaphoido-cuneiform and
intercuneiform synovial cavity ; 8, on the cuboid bone, points to the interosseous gca-
phoido-cuboid ligament; 9, internal, 10, middle, 11, external cuneiform bones; 12,
cuboid : between these several bones the interosseous ligaments are shown ; from 13 to 17,
are the metatarsal bones, with the interosseous ligaments between them; 9 to 14, the
interosseous ligament from the internal cuneiform to the second metatarsal bone ; 11 to
16, the interosseous ligament from the external cuneiform to the fourth metatarsal bone :
there are also shown in this figure, the synovial cavity of the first tarso-metatarsal arti-
culation, that between the middle and external cuneiform bones and the second and third
metatarsal ; and that between the cuboid and the fourth and fifth metatarsal bones.
TAESO-METATARSAL ARTICULATIONS. 165
third metatarsal bone articulates with the extremity of the external cunei-
form ; and the last two with the cuboid bone. The articulations are furnished
with synovial membranes, and tha boned are held in contact by dorsal, plantar,
and iiiterosseous ligaments.
The dorsal tarso-metatarsal ligaments are flat thin bands of parallel fibres,
which pass from behind forwards, connecting the contiguous extremities of
the bones before mentioned. Thus the first metatarsal bone receives a broad
thin band from the corresponding cuneiform bone ; the second receives
three, which converge to its upper surface, one passing from each cuneiform
bone ; the third has one from the external cuneiform bone ; and, finally,
the last two are bound by a fasciculus to each from the cuboid bone, and
by fibres from the external cuneiform to the fourth metatarsal bone. The
plantar ligaments are less regular ; the bands of the first and second toes are
more strongly marked than the corresponding ligaments on the dorsal sur-
face ; and those of the fourth and fifth toes, which are merely a few-
scattered fibres passing to the cuboid, receive support from the sheath of the
peroneous longus muscle. Ligamentous bands stretch in an oblique or trans-
verse direction from the internal cuneiform to the second and third meta-
tarsal bones, and from the external cuneiform to the fifth metatarsal.
The interosseous ligaments are longitudinal in direction, and have especial
interest, because of the resistance which they oppose to the surgeon in
separating the metatarsus from the tarsus, in consequence of their deep
position between the bones, a. The internal and largest of these lies to
the outer side of the first cuneiform bone, and extends from this bone to
the neighbouring side of the second metatarsal, close to the articular sur-
face, b. The external iuterosseous ligament separates the articulation of
the fourth and fifth metatarsal bones from the rest. It connects the outer
side of the external cuneiform bone to the same side of the third, and very
strongly to the inner side of the fourth metatarsal. c. Occasionally some
fibres, of less strength and importance than the preceding, are observable on
the outer side of the second metatarsal bone, connecting it to the middle
cuneiform.
The interosseous ligaments are found to vary somewhat in their connections from
those here stated, being sometimes attached at once to the contiguous sides of two
tarsal and two metatarsal bones. Attention was first particularly directed to these
ligaments by M. Lisfranc, in connection with the amputation of the foot through the
tarso-metatarsal articulation. See "Manuel des Operations Chirurgicales, &c. Par
J. Coster." 3rd edit. Paris, 1829.
Synovial membranes. There are three synovial membranes in this
irregular series of articulations, a. One belongs to the internal cuneiform
and the first metatarsal bone : the joint formed between these two bones is
altogether separate and out of the range of the rest. b. A second sy no vial
membrane is placed between the cuboid and the fourth and fifth metatarsal
bones; this is isolated on the inner side by the external interosseous liga*
ment. c. The third or middle one is placed between the middle and external
cuneiform and the second and third metatarsal bones, and is prolonged
between the two last-named bones, as well as sometimes between the third
and fourth metatarsal bones. The disposition of this last synovial mem-
brane is subject to variation.
CONNECTION OF THE METATARSAL BONES WITH ONE ANOTHER. The .meta-
tarsal bones are bound together at their tarsal and digital ends ; very firmly
in the former, and loosely in the latter situation.
The tarsal ends or bases of the four outer bones articulate with each other,
166
ARTICULATIONS OF THE LOWER LIMB.
having lateral cartilaginous surfaces provided with synovial membrane, and
are connected by dorsal, plantar, and interosseous ligaments. The dorsal
and plantar ligaments are short transverse bands stretching across the
five metatarsal bones from one to another. The interosseous fibres, lying
deeply between the bones, occupy the rough parts of their lateral surfaces :
Fig. 152.
Fig. 152. VERTICAL ANTERO POSTERIOR SECTION OF THE ANKLE-JOINT AND ARTICU-
LATIONS OF THE FOOT, A LITTLE TO THE INSIDE OF THE MIDDLE OF THE GREAT
TOE OF THE RIGHT FOOT.
1, the synovial cavity of the ankle-joint ; 2, the posterior talo-calcaneal articulation; 3,
placed above the talo-scaphoid articulation ; 3', on the astragalus above the anterior talo-
calcaneal articulation, which is continuous with the preceding : the interosseous ligament
is seen separating 2 from 3' ; 4, the inferior calcaneo-scaphoid ligament ; 5, part of the
calcaneo-cuboid or long plantar ligament ; 6, the scaphoido-cuneifonn articulation ; 7,
the first metatarso-cuneiform articulation ; 8, the first metatarso-phalangeal articulation ;
9, section of the inner sesamoid bone ; 10, the phalangeal articulation ; 1 1, placed on the
calcaneum, indicates the bursa between the upper part of the tuberosity of that bone and
the tendo Achillis.
they are of considerable strength and firmness. The intermetatirsal arti-
cular cavities are lined with synovial membrane, which in each is continued
forwards from that lining the joints formed between the bases of these bones
and the tarsus. The first aud second metatarsal bones do not articulate
laterally with each other.
Transverse metatarsal ligament. The digital extremities or heads of the
metatarsal bones are loosely connected by a transverse band, which is
identical in its arrangement with the corresponding structure in the hand,
with this exception, that it is attached to the great toe, whereas in the hand
the transverse metatarsal ligament does not reach the thumb.
ARTICULATIONS OF THE METATARSAL BONES WITH THE DIGITAL PHALANGES,
AND OF THE LATTER ONE WITH ANOTHER. The heads of the metatarsal bone*
are connected with the small concave articular surfaces of the first phalanges by
two lateral ligaments, an inferior ligament, and a synovial membrane, which
are closely similar to those which belong to the corresponding parts of the hand.
The articulations of the phalanges with one another are also constructed
on the same plan as those of the superior extremity. In each, the bones
are held in contact by two lateral ligaments and an inferior ligament or
fibrous plate ; and each of the cavities is lined by a synovial membrane.
MOVEMENTS,' &c. In the mechanism of the foot three arches are distinguishable, two
of them longitudinal and one transverse ; all of them capable of being flattened some-
MYOLOGY. 167
what by pressure from above, and combining to secure elasticity of the parts at rest
or in motion. The inner arch is formed by the os calcis, astragalus, scaphoid, and
three cuneiform bones, together with the three inner toes ; the head of the astragalus
being the key-stone, and being supported in its position, not by immoveable piers,
as would be the case in an arch of mason-work, but by them in connection with the
inferior calcaneo-scaphoid ligament. The outer arch is formed by the os calcis,
cuboid bone, and two outer toes, and is supported by the strong inferior calcaneo-
cuboid ligaments. Thus the calcaneo-scaphoid and calcaneo-cuboid ligaments are
stretched by the whole weight of the body bearing down upon the arch, and
prevent the too great flattening of the instep ; an action in which they are assisted,
however, by the plantar aponeurosis. The transverse arching of the foot is most
marked in the line of tarso-metatarsal articulations, and is maintained by the wedge-
shape of the bones and by inferior ligaments. The weight of the body, falling upon
the balls of the toes when the heel is raised, tends to spread out the metatarsal bones
at their distal extremities, and to flatten the transverse arch, which recovers its
position when the pressure is removed. Between the astragalus and the calcaneum
only one kind of motion is possible, the centre of which is the interosseous
astragalo-calcaneal ligament, and is of such a nature, that when the posterior part of
the os calcis slides inwards and upwards beneath the astragalus, its cuboid extremity
moves downwards and outwards. A certain amount of gliding movement is also
allowed between the tarsal and metatarsal bones, and that most considerably between
the cuboid bone and outer toes. Thus it happens that if the foot is flexed against the
leg, and then is gradually extended by force applied to the toes, as by the action of
the flexores digitorum muscles, the first part of the movement is accomplished at the
ankle, and consists of extension, with only a slight inward turning of the toes;
further extension is accomplished by movement between the calcaneum and astra-
galus, and is accompanied by depression of the outer edge of the foot ; and after that
a little more extension, accompanied by more considerable depression of the outer
edge of the foot, is effected at the tarso-metatarsal articulations. The direction of the
movement of extension of the toes at the metatarsal-phalangeal articulations is
upwards and outwards, so that although the great toe is in a line with the inner edge
of the foot when resting on the ground, it is no longer so when over-extended, as, for
instance, ^Yllen supported by a shoe.
SECTION III. MYOLOQY.
UNDER the title MYOLOGY will be brought the systematic description of
the form, position, and relations of the muscles of the body with their
tendons, and in the same section it will be convenient to include that of
the fasciae and aponeuroses.
As many of the muscles consist of tendinous as well as muscular parts,
the description of the tendons and their sheaths necessarily forms a part of
that of the muscles ; and farther, as it is impossible to separate the exami-
nation of the attachmemts of a muscle, or of groups of muscles, from the
study of the motions produced by them, the statement of the action of the
muscles will accompany their anatomical description.
In the description of the muscles, it is customary to state the attach-
ments of their opposite ends under the names of origin and insertion ; the
first term being usually applied to the more fixed or proximal, and the
second to the more movable or remote attachment : but it is to be observed,
that it is sometimes difficult to lay down a rule for the correct use of these
terms, and that in almost all instances it is of importance to consider the
action of a muscle as it may affect the motions of the parts attached to
both of its extremities.
As the muscles belong to the double symmetrical parts, it will be under-
168 MYOLOGY.
stood that it is sufficient, as in the bones and joints, to describe those
occupying one side of the body.
The description of the involuntary and unstriped muscles connected with
internal organs is excluded from the present section, as is also that of
some small striped muscles situated in certain complicated organs, such as
the larynx and ear, as it is more expedient that those muscles should be
treated of under the several organs to which they belong. In the arrange-
ment to be adopted in the anatomical description of the external and volun-
tary muscles, it is almost impossible to follow a strictly systematic order
founded exclusively, either upon their position in the several regions of the
body, or upon their actions : in the following section, therefore, an arrange-
ment is adopted which is based in part on both of these considerations, and
which seems to be the most simple and advantageous to the student.
FASCLE. The term Fascia includes all the membranous dispositions of
reticulated or felted fibrous tissue. These structures have usually been
distinguished as the superficial and the deep ; the former consisting of looser
and finer substances, and passing by their slenderer kinds into the finer
varieties of connective tissue ; while the latter, denser in character, fre-
quently exhibit more or less regular arrangements of strong white fibres,
giving them a shining appearance, and are often termed aponeuroses.
The connective tissue of the body being that in which all others are em-
bedded, may be considered as forming a continuous meshwork of fasciae of
various degrees of firmness arranged so as to enclose shut spaces, within which
the other parts are contained. Thus each fasciculus of muscle is surrounded
by connective tissue ; the larger fasciculi are separated by stronger par-
titions, and the whole muscle is invested with a layer of such distinctness,
that it may appropriately be styled a fascia. So also the sheaths of vessels
are formed of this substance ; and in certain parts stronger septa, having
attachment to bone, and continuous with the periosteum, which likewise
belongs to the series of white fibrous membranes, form partitions between
dissimilar structures.
Superficial Fascia. Under this name, or as subcutaneous fascia, is described
the layer of loose tissue of varying density, which is placed immediately
below the skin, all over the body. It is the web which contains the sub-
cutaneous fat, the panniculus adiposus, and in some regions superficial
muscles, as the panniculus carnosus. From the subcutaneous tissue of
the eyelids, however, as well as from that of the penis and scrotum, adipose
matter is entirely absent. It is to be noticed also that between the muscles
and the subcutaneous fat there is always a certain amount of fascia devoid
of adipose matter, and that it is in this stratum that the trunks of the
subcutaneous vessels and nerves are found. But when the fat becomes
absorbed, the stroma in which it was deposited is still left, and its meshes
approach one another, so that in lean subjects a more fibrous condition of
the subcutaneous fascia is often found than in others.
Deep Fascice and Aponeuroses. Under the name of deep fascia is com-
prehended that stronger layer of fibrous or connective tissue which, lying
more close to the muscles, gives them a general investment or dips between
them, and forms a nearly continuous covering of the body beneath the
superficial fascia. It is chiefly to the stronger parts of this fascia that the
name of aponeuroses has been given. Those covering the muscles have
been named aponeuroses of investment (Bichat), to distinguish them from
proper tendinous expansions, or aponeuroses of insertion, of muscles. This
distinction, however, is far from being universally applicable : aponeuroses
EPICRANIAL MUSCLES. 169
of insertion are often continued into aponeuroses of investment, as in the
instance of the glutens maximus, or into mere fascia, as at the lateral parts
of the occipito-frontal aponeuroses, or the cranial origin of the trapezius
muscle. The principal aponeuroses of investment are those which incase
the muscles of the limbs, binding them down in a common sheath, and
connected in various places by septa with the bones. They are characteristic
of the limbs, there being no structure entirely C3rresponding to them in
the rest of the body.
MUSCLES OF THE HEAD AND NECK.
SUPERFICIAL MUSCLES.
EPICRANIAL MUSCLES. Under the title of occipito-frontalis muscle are
comprehended a pair of occipital and a pair of frontal muscles, together
with a thin aponeurosis extending over the cranium, and uniting the
anterior and posterior muscles together.
a. The occi2ntalis muscle, thin and subcutaneous, is attached inferiorly
by short tendinous fibres to the external two-thirds, sometimes much less,
of the superior curved line of the occipital bone, and to the mastotd portion
of the temporal bone, immediately above the attachment of the sterno-
mastoid muscle. Its fleshy fibres, from one to two inches in length, are
directed upwards, and terminate in distinct tendinous fibres, continuous
with the epicranial aponeurosis. Between the muscles of opposite sides is
an interval of variable size occupied by a part of that aponeurosis.
6. The frontalis muscle, longer and broader and of a paler colour than
the occipitalis, arises superiorly in a convex line from the epicranial
aponeurosis, while inferiorly its innermost fibres are continuous with the
pyramidalis nasi muscle, and the others are blended with the corrugator
supercilii and with the orbicularis palpebrarum, as far outwards as the
external orbital process of the frontal bone. The fibres are nearly vertical,
running slightly inwards ; the margins of the right and left muscles are
united for a short distance above the root of the nose, but are separated by
an angular interval superiorly.
c. The epicranial or occipito-frontal aponeurosis extends over the upper
surface of the cranium uniformly from side to side, without division. Pos-
teriorly it is attached to the occipitales muscles, and to the protuberance
and superior curved lines of the occipital bone, and anteriorly it terminates
in the frontales muscles, while laterally it presents no distinct margin, but
below the temporal ridge becomes thinner and less aponeurotic, and gives
attachment to the superior and anterior auricular muscles. Its fibres are
chiefly longitudinal, and are most distinctly tendinous where they give
attachment to the occipitales muscles. Its outer surface is firmly bound to
the skin by an abundant network of fibrous tissue, constituting the so-
called superficial fascia, by the meshes of which the subcutaneous fat is
divided into granules ; while its deep surface glides upon the subjacent peri-
cranium, to which it is loosely adherent through the medium of a delicate
connective tissue devoid of fat.
ACTIONS. By the contraction of the whole occipito-frontalis muscle, the scalp is
drawn backwards, and the eyebrows elevated ; by the contraction of the frontales
muscles alone, the eyebrows are elevated, the scalp pulled forwards, and the skin of
the forehead thrown into transverse wrinkles ; by the contraction of the occipitales
muscles alone, the scalp is drawn backwards ; and by the alternate action of the
occipitales and frontales muscles, the scalp is moved backwards and forwards. In
170
MUSCLES OF THE HEAD AND NECK.
many persons, however, there is only a partial control over the action of these
muscles, limited to the elevation of the eyebrows and horizontal wrinkling of the
forehead.
AURICULAR MUSCLES. Besides minute bundles of muscular fibres which
pass from one part of the pinna of the auricle to another, and which will be
Fig. 153.
Fig. 153. SUPERFICIAL VIEW OF THE MUSCLES ON THE LEFT SIDE OF THE HEAD AND
NECK (slightly altered from Bourgery).
a, cranial aponeurosis ; 6, superior curved line of the occipital bone ; c, ramus of the
lower jaw; d, lower edge of the hyoid bone; e, head of the clavicle. 1, anterior or frontal,
and 1', posterior or occipital part of the occipito-frontalis muscle; a, the aponeurotic covering
of the cranium extending between the two portions of the muscle; 2, superior auricular; 2',
anterior auricular; 3, posterior auricular in two fasciculi ; 4, is placed in front of the temple
close to the outer part of the orbicularis palpebrarum; 5, pyramidalisnasi; 6, triangularis
nasi or compressor naiium ; 7, levator labii supcrioris aloeque nasi ; 8, orbicularis oris ;
MUSCLES OF THE EYELIDS. 171
8', its attachment to the columella nasi, or depressor nasi ; 9, levator labii superioris,
and close by it zygomaticus minor ; farther back passing from the + obliquely down
towards 8, zygomaticus major ; and between the zygomatici, in shadow, is seen a portion
of the levator anguli oris ; 10, quadratus menti or depressor labii inferioris ; 11, trian-
gularis oris or depressor anguli oris ; 12, points to the situation of levator menti; 13, is
placed on the masseter, it is immediately above the risorius or upper horizontal fibres of
the platysma myoides, and a line points from it to the buccinator; 14, platysma myoides;
15, placed on the upper part of the sterno-mastoid, points by a line to the posterior belly
of the digastric muscle ; 15', the sternal tendon of the sterno-mastoid, a part of its clavicular
portion is seen near e: 16, trapezius ; 17, splenius capitis ; +, splenius colli ; 18, levator
scapulae; 19, stern o - hy oid ; 20, omo-hyoid ; 21, pectoralis major, its pectoral part ; 21',
its clavicular part ; 22, deltoid.
most conveniently described along with that structure, there are attached to
the external ear three larger, but still very slightly developed, muscles,
which serve to move it as a whole.
The auricularis superior or attollens auriculam, the largest of the three,
arises in the temporal region of the head from the epicranial aponeurosis.
Its fibres are extremely delicate, and radiated in arrangement, and are
inserted by a compressed tendon into the cartilage of the ear at the upper
and anterior part of the helix and upper part of the concha.
The auricularis anterior or attrahens auriculam, scarcely separated from
the preceding muscle, is pale and indistinct, and is attached to the thin
lateral prolongation of the epicranial aponeurosis, from which it passes back-
wards to be inserted into the fore part of the helix.
The auricularis posterior or retrahens auriculam muscle, consists of two
or three thin fasciculi, which arise from the mastoid process by short
aponeurotic fibres, and are inserted into the back part of the concha. The
fibres are much deeper in colour and more distinctly marked than in either
of the other auricular muscles.
ACTIONS. The three auriculares muscles respectively draw the pinna of the ear
upwards, backwards, and forwards. In the majority of persons their action is not
directly under voluntary control.
MUSCLES OF THE EYELIDS. These are four in number namely, the
orbicularis palpebrarum and tensor tarsi, the corrugator supercilii, and the
levator palpebrse superioris.
The orbicidaris palpebrarum is a thin elliptical muscle closely adherent to
the skin, surrounding the fissure between the eyelids and covering their
surface, and spreading for some distance outwards on the temple, upwards
on the forehead, and downwards on the cheek. The fibres forming con-
centric curves are attached by their extremities at the inner angle of the
orbit : 1st, to the edges and anterior surface of the tendon afterwards
described ; 2nd, to the surface of the nasal process of the superior-maxilla,
near the anterior margin of the lachrymal groove ; and 3rd, to the internal
angular process of the frontal bone.
The fibres situated in the eyelids are thin, pale and little curved, and
conceal the tarsal cartilages : they are sometimes distinguished by the name
" ciliaris." The peripheral fibres, "orbicularis latus," more largely deve-
loped, rest on the cheek and margin of the orbit. Superiorly this muscle
conceal the corrugator supercilii, with which and the occipito-frontaJis it
is intimately connected ; inferiorly it covers the origin of the elevators of
the upper lip, part of the common elevator of the lip and nose, and the
lachrymal sac ; and externally it lies upon a part of the temporal fascia.
The tendon of the orbicularis muscle (tendo palpebrarum). At the inner
commissure of the eyelids is a small tendon, which is often obscured by the
172
MUSCLES OF THE HEAD AND NECK.
fibres of the muscle, but is rendered apparent by drawing the lids outwards.
This tendon is about two lines in length, and less than one in breadth, and
is attached to the anterior margin of the lachrymal groove ; thence it runs
Fig. 154.
Fig. 154. SUPERFICIAL AND DEEP VIEW OP THE MUSCLES OF THE HEAD AND NECK,
FROM BEFORE (altered from Bourgery).
On the left side, the platysma alone has been removed ; on the right side, portions of
the zygomatic arch and clavicle, the superficial muscles of the cranium and face, the
ma'seter, trapezius, sterno-mastoid and pectoralis major muscles have been removed ; a,
right alar cartilage of the nose ; 6, upon the lobe of the right ear, points to the coronoid
process of the lower jaw ; c, the body of the hyoid bone ; d, symphysis of the lower jaw ;
e, upon the subclavian groove of the first rib, lying in which is the cut end of the sub-
clavian artery ; /, the glenoid cavity of the scapula; g, the right zygomatic arch separated
from the malar bone ; 7i, upon the temporal ridge of the frontal bone ; i, above the supra-
orbital ridge ; 1 , frontalis muscle ; 2, superior auricular ; 2', insertion of the anterior
MUSCLES OF THE EYELIDS AND NOSE. 173
auricular ; 3, corrugator supercilii ; 4, malar portion of the orbicularis palpebrarura ; 4',
palpebral portion ; below i, the expanded insertion of levator palpebrre superioris in the
eyelid ; 5, pyramidalis nasi ; 6, insertion of the triangulares nasi on the dorsum of the
nose ; 7, levator labii superioris alaeque nasi ; 8, orbicularis oris of the left side ; 8',
outer part of the same on the right side, the inner part being removed ; 9, levator labii
superioris; -f, zygomaticus minor; 10, zygomaticus major; 11, depressor anguli oris;
12, depressor labii inferioris ; d, points to the cut ends of the levatores menti ; 13, placed
on the left masseter, points to the buccinator ; 13', buccinator, of the right side, a
portion of the parotid duct passing through the muscle ; 14, levator anguli oris, seen
also on the left side behind the zygomaticus minor. The remaining references which
apply to the muscles of the neck will be found described at page 194.
horizontally outwards to the inner commissure of the eyelids, where it
divides into two thin fibrous lamellae, which diverge as they pass outwards
in the substance of the eyelids, and terminate in the tarsal cartilages.
One surface of the tendon is subcutaneous ; the other crosses the lachrymal
sac a little above the centre, and from it a thin but firm fascia is given off,
which spreads over the lachrymal sac, and adheres to the margins of the
groove which lodges it.
The tensor tarsi Horner, (musculus sacci lachrymalis,) consists of very
thin fibres resting on the fascia just mentioned. It is only a deep portion
of the insertion of the marginal fibres of the ciliary part of the orbicularis
muscle : two slips, one from each eyelid, passing behind the lachrymal
canals, unite on the surface of the lachrymal sac before reaching their attach-
ment on the posterior part of the lachrymal bone.
The corrugator supercilii is a small muscle narrower below than above,
placed at the inner side of the eyebrow. It arises from the inner extremity
of the superciliary ridge of the frontal bone ; thence its fibres proceed
outwards and a little upwards, and end, at the middle of the orbital arch,
by becoming blended with those of the orbicularis and occipito-frontalis
muscles, by which it is concealed.
This muscle crosses the supratrochlear branch of the ophthalmic nerve and the
accompanying artery as they emerge from the orbit.
The levator palpebrce superioris is a muscle occupying the upper part of the
orbit, but the insertion of which is seen in the dissection of the upper eyelid,
in which it forms a broad fibrous expansion which curves downwards
towards its margin, and is inserted under cover of the orbicularis muscle
into the forepart of the tarsal cartilage. It will be described along with
the muscles of the orbit.
ACTIONS. The orbicularis palpebrarum closes the eyelids. In the ordinary closure
of the eye, it is chiefly the upper lid which moves, being depressed by the superior half
of the ciliary part of the muscle ; but in forcible closure both eyelids move, and not
only come together, but are drawn towards the nose at the same time that the eyebrows
are drawn downwards and inwards, the whole fibres of the orbicularis being thus
contracted and approached towards the tendo palpebrarum. In those circumstances
the fibres which form the tensor tarsi, being contracted like the others, compress the
lachrymal sac, and prevent the introduction into it of the lachrymal secretion from
the conjunctiva. The corrugator muscles draw the skin of the forehead downwards
and inwards, raising longitudinal furrows, as in frowning. The upper eyelid is
supported by the levator palpebrse, and droops when that muscle is paralysed. On
the other hand, paralysis of the orbicularis is attended by an inability to close the
eyelids.
MUSCLES OF THE NOSE. Under this head may be conveniently grouped
not only the compressor naris and smaller muscles which act upon the nose
alone, but also the pyramidalis nasi which acts on the forehead, and the
levator labii superioris alaeque nasi whose action is common to the nose and lip.
174 MUSCLES OF THE HEAD AND NECK.
The pyramidalis nasi, continuous with the innermost fibres of the fron-
talis muscle, extends downwards from the root of the nose, over the
upper part of it, and terminates by a tendinous expansion in connection
with the compressor naris muscle. The muscles of opposite sides, united
superiorly, diverge slightly as they descend.
The compressor naris, a thin triangular muscle, arises narrow and fleshy
from the canine fossa in the superior maxillary bone, and proceeding inwards,
gradually expands into a thin aponeurosis, which is partly blended with that
of the corresponding muscle of the opposite side, and with the pyramidalis
nasi, and is partly attached to the cartilage of the nose. It is concealed at
its origin by the proper elevator of the lip, and is crossed by the common
elevator.
Fig. 155. pig 155 MUSCLES OP THE SIDE OF THE NOSE AND
UPPER LIP.
1, pyramidalis nasi ; 2, levator labii superioris aljeque
nasi ; 3, compressor naris or triangularis ; 4, levator
proprius alee nasi anterior ; 5, levator proprius alse nasi
posterior or dilatator ; 6, depressor alee nasi ; 7, orbicu-
laris oris ; 7*, naso-labialis.
The levator labii superioris alceque nasi, the
common elevator of the lip and nose, lies along
the side of the nose, extending from the inner
margin of the orbit to the upper lip. It arises
by a pointed process from the upper extremity
of the nasal process of the superior maxillary
bone, and, as it descends, separates into two
fasciculi ; one of these, much smaller than the
other, becomes attached to the wing of the nose,
whilst the other is prolonged to the upper lip,
where it is blended with the orbicularis and the
special elevator muscle. It is subcutaneous, except at its origin, where the
orbicularis palpebrarum overlaps it a little.
Anomalous Fibres. Beneath the common elevator of the lip and ala of the nose,
and connected by the lower end with the origin of the compressor naris, will be found
a longitudinal muscular slip, more than an inch in length, attached exclusively to the
superior maxillary bone. It was named " rhomboideus " by Santorini and (in con-
sequence of being attached only to one bone, and producing therefore no motion)
" anomalus " by Albinus.
The depressor alee nasi is a small flat muscle which arises from the superior
incisor fossa, and is inserted into the septum and posterior part of the ala of
the nose. The external fibres curve forwards and downwards to the ala.
Besides the muscles above described there are other irregular and often
indistinct fibres which cover the small alar cartilages of the nose. Of these
the following may be distinguished.
The levator proprius alee nasi posterior, or dilatator naris posterior, is
attached to the margin of the ascending process of the superior maxillary
bone and the smaller (sesamoid) cartilages of the ala nasi on the one hand,
and to the skin on the other. Another set of fibres, the levator proprius alee
nasi anterior, or dilatator naris anterior, is interposed between the cartilage
of the aperture of the nose and the skin, to both of which it is attached.
ACTIONS. The pyramidalis muscle, being continuous with the occipito-frontalis, is
the means of giving that muscle a more fixed attachment to the dorsum of the nose,
MUSCLES OF THE LIPS AND MOUTH. 175
and must aid it in drawing down the integument of the forehead ; but it probably
acts also as an opponent to the compressor naris muscle. The compressor naris, acting
along with its fellow of the other side, depresses the cartilaginous part of the nose,
and to some extent also compresses the alae together. The actions of the other
muscles are sufficiently indicated by their names ; the dilatation of the alae is per-
ceptible in natural inspiration, and is well marked in dyspnoea.
MUSCLES OF THE LIPS AJSD MOUTH. Around the orifice of the mouth
are situated an orbicular muscle with concentric fibres, and numerous other
muscles, whose fibres converge towards the aperture, viz., superiorly the
common elevator of the lip and nose already described, the proper elevator
of the upper lip, the elevator of the angle of the mouth and the zygomatic
muscles, laterally the risorius and buccinator muscles, and, inferiorly, the
depressor of the angle of the mouth and that of the lower lip j and lastly,
acting indirectly on the lower lip, the levator menti.
The orbicular is oris, or sphincter oris, consists of a labial or inner, and a
facial or peripheral part. The labial or marginal portion reaches outwards
from the oral aperture as far as the red part of the lip, and forms a slightly
convex fasciculus of pale fine fibres closely applied to each other. Its fibres
are free from bony attachment, and are traceable from one lip to another
round the corner of the mouth. The facial portion, thinner and wider than
the other, blends by its outer border with the several muscles that con-
verge to the mouth from the contiguous parts of the face, and is more
particularly stretched outwards by its attachment to the buccinator muscle,
the fibres of which seem almost to be continuous with the deeper part of
the orbicularis. Besides those fibres it has others that are attached to the
subjacent cartilage and bone ; viz., in the upper lip two bundles for each
half ; and in the lower lip one for each. In the upper lip one of the fleshy
slips (accessorius orbicularis superioris) is thin and weak, and is attached
opposite the incisor teeth, close to the alveolar edge of the upper jaw-bone ^
and the other, thicker and pointed, is fixed to the septum of the nose. In
the lower lip the reinforcing fasciculus (accessorius orbicularis inferioris)
arises from the surface of the lower jaw, near the root of the canine tooth,
and external to the levator labii inferioris. From these points of attach-
ment the fibres are directed outwards towards the angle of the mouth and
blend with the rest.
To the inner part of the orbicularis oris muscle the skin of the lips is closely con-
nected, whilst over the outer part fatty tissue is interposed between them. The deep
surface is in contact with the mucous membrane and the labial glands, as well as with
the coronary arterial arch in each lip.
The levator labii superioris arises immediately above the infraorbital
foramen, close to the lower border of the crbit, from the superior maxillary
and malar bones, and passes downwards and a little inwards to be blended
with the orbicularis and other muscular fibres in the upper lip.
At its origin this muscle is overlapped by the orbicularis palpebrarum, but its
lower part is subcutaneous ; it partly conceals the levator anguli oris, and the com-
pressor naris, and beneath it the infraorbital vessels and nerve emerge from the
canal of that name.
The levator anguli oris, or musculus caninus, arises in the canine fossa
immediately below the infraorbital foramen, inclines downwards and slightly
outwards, and is inserted into the angle of the mouth.
At its origin this muscle is concealed by the elevator of the upper lip ; its anterior
176 MUSCLES OF THE HEAD AND NECK.
surface supports the infraorbital nerve and artery, which separate it from the preceding
muscle; the posterior surface lies on the superior maxilla and the orbicularis and
buccinator muscles, with which and the depressor anguli oris the fibres are blended.
The zygomatici are two narrow and subcutaneous fasciculi of muscular
fibres, extending obliquely from the most prominent part of the cheek to
the angle of the mouth, one being thicker and longer than the other.
a. The zygomaticus minor, a very small muscle, arises from the anterior
and inferior part of the malar bone, and inclines downwards and forwards
to terminate by joining the outer margin of the levator labii superioris ;
sometimes near the origin of that muscle. It lies internal to the zygo-
maticus major, but distinct from it in the whole length, and is sometimes
joined by some fibres of the orbicularis palpebrarum : in some instances
it is replaced by a fleshy slip from that muscle ; in others it is altogether
wanting.
b. The zygomaticus major, placed externally to the smaller muscle of the
same name, arises from the malar bone near the zygomatic suture, from
which it descends to the angle of the mouth, where it is continued into the
orbicularis and depressor anguli oris.
The risorius or smiling muscle (Santorini), consisting of some very thin
fasciculi, commences in the fascia over the masseter, or on the parotic gland,
and, extending transversely inwards in the fat of the cheek, joins the orbicu-
laris and depressor anguli oris at the angle of the mouth. It is united with
the fibres of the platysma close to their termination, and is by many re-
garded as a part of that muscle.
The buccinator muscle consists of a flat and thin but strong set of fibres
in contact with the mucous membrane, and forming a considerable part of
the wall of the mouth. It is attached by its upper and lower margins to
the outer surface of the alveolar parts of the maxillary bones, outside the
molar teeth, and between these bones it is fixed behind to a narrow band of
tendinous fibres, the pterygo-maxillary ligament, a structure which extends
from the internal pterygoid plate to the posterior extremity of the mylo-
hyoid ridge of the lower jaw close to the last molar tooth, and separates
the buccinator muscle from the superior constrictor of the pharynx. From
these points the fibres of the muscle are directed forwards, approaching
each other, so that the muscle is narrowed and proportionally thickened
near the angle of the mouth, where it becomes incorporated with the
orbicularis. The fibres near the middle of the muscle cross each other,
those from above entering into the lower lip, and those from below into the
upper one ; but the higher and lower fibres are directed into the correspond-
ing lip without decussation.
The buccinator is covered and supported by a thin fascia, which is closely adherent
to the muscular fibres ; and is overlapped by the triangularis oris, the terminal fibres
of the platysma myoides, and by the facial artery and vein ; it is also covered by the
masseter and zygomatici, from which it is separated by a quantity of soft adipose
tissue of a peculiar character. Opposite the second molar tooth of the upper jaw, its
fibres give passage to the duct of the parotid gland.
The depressor anguli oris, or triangnlaris oris, is broad at its origin from
a line on the external surface of the lower jaw near its base ; passing up-
wards it is collected into a narrower bundle which is inserted into the
orbicularis at the angle of the mouth.
This muscle is covered by the skin, and, at its insertion, by the zygomaticus major,
under which its fibres pass ; it conceals part of the buccinator and of the depressor
of the lower lip.
MUSCLES OF THE LIPS AXD MOUTH.
Fig. 156.
177
Fig. 156. DEEP VIEW OP THE MUSCLES OP THE LEFT SIDE OP THE HEAD AND NECK
(modified from Bourgei-y). g
a, vertex of the head ; b, superior curved line of the occipital bone ; c, ramus of the
lower jaw; </, its coronoid process ; d, body of the hyoid bone ; e, sternal end of the clavicle;
e', acromial end ; /, malar bone divided to show the insertion of the temporal muscle ;
/', zygoma divided, and external lateral ligament of the jaw ; g, thyroid cartilage ; h, placed
on the lobe of the auricle, points to the styloid process ; 1, temporal muscle ; 2, corrugator
supercilii ; 3, pyramidalis nasi ; 4, lateral cartilage of the nose covered by the triangularis
nasi ; 5, levator labii superioris proprius ; 6, levator anguli oris ; 7, outer part of the
orbicularis oris, the part below the nose has been removed to show more deeply ; 8, de-
pressor alse nasi ; 9, placed on the ramus of the jaw, points to the buccinator muscle,
through which the parotid duct is seen passing ; 10, quadratus menti; 11, levator menti ;
12, 12, anterior and posterior bellies of the digastric ; 13, placed on the angle of the jaw,
points to the stylo-hyoid muscle; 14, points to the mylo-hyoid; 15, to the hyo-glossus,
between which and 13, is seen a part of the stylo-glossus ; 16, sterno-hyoid ; 17, on the
clavicle, indicates the lower, and 17', the upper belly of 'the omo-hyoid ; 18, a small part
of the sterno-thyroid ; 19, thyro-hyoid ; 20, 21, on the sterno-mastoid muscle, point, the
first to the middle, the second to the lower constrictor of the pharynx ; 22, trapezius ;
23, upper part of the coraplexus ; 24, splenius capitis ; 25, splenius colli ; 26, levator
scapulae ; 27, middle scalenus ; + , posterior scalenus ; 28, anterior scalenus.
N
178 MUSCLES OF THE HEAD AND NECK.
The depressor labii inferioris, or quadratus menti, arises from the lower
jaw by a line of attachment extending from near the symphysis to a little
beyond the mental foramen ; thence it ascends with an inward inclination,
unites with its fellow, and blending with the orbicularis oris is inserted into
the lower lip. Its fibres are intermixed with much adipose matter.
It covers the nerve and artery issuing from the mental foramen.
The levator labii inferioris or levator menti arises by a narrow head from
the incisor pit of the lower jaw, and, expanding in a nearly vertical plane, is
directed forwards, downwards, and slightly inwards, to the integument of
the chin between the depressors of the lower lip.
ACTIONS. The orbicularis oris acting alone draws the lips together in both the
vertical and transverse directions. Acting in conjunction with the buccinators it
closes the lips, while at the same time they are elongated transversely. Its facial
portion acting alone projects the lips. The labial portion, when acting in concert
with the converging muscles, tightens the lips, one or both, against the teeth. The
convergent muscles each draw their oral points of insertion in a direction corresponding
to that of their muscular fibres. The common elevator of the lip and nose and the
upper part of the orbicularis oris act on both the upper lip and the ala of the nose
together the one elevating, the other depressing them. When the cheeks are dis-
tended with air in the mouth, it is by the action of the buccinator that the rush of
the air through the narrowed oral aperture is regulated, as in whistling, or performance
on a wind instrument ; hence the name " trumpeter's muscle " sometimes given to
the buccinator. The levator menti not only draws upwards the integument of the
chin, but it also protrudes the lower lip, as in pouting. The muscles attached to the
angles of the mouth are, along with others of the face, intimately connected with
the expression of the passions : those which pass downwards not only raise the upper
lip, but also push upwards the cheek, and thus elevate the margin of the lower eyelid,
as in laughter : and those which descend from the angle of the mouth depress that
part, as in weeping. (On the action of the facial muscles may be consulted, more
especially, Sir Charles Bell, " Anatomy and Philosophy of Expression.")
THE PLATYSMA MYOIDES is a pale coloured thin sheet of muscular fibres,
superficial to the deep cervical fascia, and extending over the front and
sides of the neck and lower portions of the side part of the face. Its
fibres, which are pale and thin in their whole extent, rise by thin bands
from the clavicle and acromion, and from the fascia covering the upper part
of the deltoid, pectoral, and trapezius muscles ; thence they proceed up-
wards and inwards over the clavicle and the side of the neck, gradually
narrowing and approaching the muscle of the opposite side. At the lower
jaw the greater number of the fibres are inserted into the side of that bone
from the symphysis to the attachment of the masseter ; the inner fibres
mingle with those of the opposite platysma in front of the symphysis, and
even cross from the one side to the other below the chin, for about an inch,
those of the right side overlapping those of the left ; and the posterior
fibres are prolonged upon the side of the face as far as the angle of the
mouth, where they become blended with the muscles in that situation, or in
some instances they reach the fascia over the parotid gland, and the cheek-
bone. The uppermost fibres pass into those receiving the name of risorius.
ACTION. The platysma, being much less developed in man than in animals, has a
comparatively limited action in the human subject; it assists in drawing the angle of
the jaw downwards and outwards, and protects parts more deeply situated in the
MUSCLES OF THE ORBIT. 179
neck. It is the only representative of a subcutaneous group of muscles largely
developed in most mammals, by which very varied movements of the skin and some
superficial parts may be given, as, for example, when the horse communicates a rapid
motion to the skin to free itself from insects, or the dog shakes off the water after
swimming, or the hedgehog elevates its spines ; and which is known collectively as
the panniculus carnosus.
MUSCLES OF THE ORBIT.
In this group will be described seven muscles, namely, the elevator of
the upper eyelid already alluded to, and six muscles of the eyeball, viz,
the four straight and the two oblique muscles. Of these muscles, the inferior
oblique alone is confined to the fore part of the orbit ; all the rest take their
origin at its back part, and pass longitudinally forwards to their insertions
in front.
The levator palpebrce superioris is a slender muscle, which arises, pointed
and tendinous, above and in front of the margin of the optic foramen, and,
passing forwards over the eyeball, ends in a fibrous expansion inserted into
the anterior surface of the tarsal cartilage of the upper eyelid.
Between this muscle and the roof of the orbit are situated the fourth and frontal
nerves, and beneath it are the superior rectus muscle and the globe of the eye. In
the lid, it is placed behind the palpebral ligament, close to the membrana
conjunctiva.
The four straight muscles of the eye surround at their origin the optic
nerve, and, passing forwards from that point, are inserted into the front of
the globe of the eye at four opposite equidistant parts, by delicate expanded
tendons which become blended into one at their termination.
The superior rectus arises close in front of the foramen opticum, and
beneath the levator palpebrse ; the inferior rectus, internal rectus, and
external rectus are united in a common tendinous attachment around the
circumference of the optic foramen, except above. But the external rectus
differs from the others in having two heads of origin : the upper head unites
with that of the superior rectus, the second head arises from a bony point
on the lower margin of the sphenoidal fissure close to its wider inner end ;
and other fibres are implanted into a fibrous band between the heads of
origin. The four recti thus attached posteriorly, pass forwards, one above,
one below, and one on each side of the eyeball, becoming flattened as
they lie in contact with it, and are inserted by short membranous tendons
into the fore part of the sclerotic coat, at an average distance of four lines
from the margin of the cornea.
In length and breadth there are some differences among these muscles. The
external rectus exceeds the internal one in length. On the other hand, the internal
rectus has some advantage in width, being broader than any ; and the superior
appears rather the narrowest of all. Between the heads of the external rectus is a
narrow interval, which gives transmission to the third and sixth nerves and the nasal
branch of the fifth nerve, with the ophthalmic vein.
The superior oblique or trochlearis is a narrow elongated muscle, placed
at the upper and inner part of the orbit, internally to the levator palpebrae.
It arises about a line in front of the inner part of the optic foramen ;
thence it proceeds towards the internal angle of the orbit, and terminates in
a round tendon which passes through a fibre-cartilaginous ring or pulley
N 2
180
MUSCLES OF THE HEAD AND NECK.
(trochlea) attached to the fovea trochlearis of the frontal bone ; it is there
reflected outwards and backwards, and passes between the eye and the
superior rectus to be inserted into the sclerotic coat midway between the
superior and external recti muscles, nearly equidistant from the cornea and
the entrance of the optic nerve. A sy no vial sheath lines the contiguous
surfaces of the tendon and pulley.
This muscle is covered by the roof of the orbit, the fourth nerve entering its upper
surface ; and beneath it lie the nasal nerve and the internal rectus muscle.
Fig. 157.
r ~ I
Fig. 157. A, VIEW OF THE MUSCLES
OP THE RIGHT ORBIT, PROM THE
OUTSIDE, THE OUTER WALL HAVING
BEEN REMOVED.
B, EXPLANATORY SKETCH OP THE SAME
MUSCLES.
a, supraorbital ridge ; b, lower margin
of the orbit formed by the superior max-
illary bone ; c, anterior clinoid process ;
d, posterior part of the floor of the
orbit above the spheuo-maxillary fossa ;
e, side of the body of the sphenoid
bone below the optic foramen and sphe-
noidal fissure ; /, sinus maxillaris ;
1, anterior part of levator palpebrse
superioris, where it is inserted into
the eyelid ; 2, pulley and tendon of the
superior oblique muscle ; 3, tendon of
the superior rectus muscle at its inser-
tion upon the eyeball ; 4, in A, outer
surface of the external rectus ; 4 , in B,
the anterior or inserted tendon of the
same muscle, a part of which has been
removed ; the double origin of the muscle
is shown at the apex of the orbit ; 5,
the inferior oblique muscle crossing the
eyeball below the inferior rectus ; 6, the
inferior rectus ; 7, in B, the inside of
the internal rectus, seen in consequence
of the removal of a part of the external
rectus, and near it, the end of the optic nerve cut short close to the place of its entrance
into the eyeball.
The inferior oblique is the only muscle of the eye which does not take
origin at the apex of the orbit. It arises from a minute depression in
the orbital plate of the superior maxillary bone, just within the anterior
margin of the orbit, and close to the external border of the lachrymal
groove. The muscle inclines outwards and backwards between the inferior
rectus and the floor of the orbit, and ends in a tendinous expansion, which
passes between the external rectus and the eyeball, to be inserted on the
external and posterior aspect of the globe.
ACTIONS. The recti muscles turn the eye upwards, downwards, and from side to
side, thus placing the axis of the eye in these or any intermediate directions. Evidence
is against the supposition that the recti muscles are capable of altering the position of
the eyeball in an antero-posterior direction, nor is it probable that they can in any
perceptible degree change its form. (Jacob, " On Paralytic, Neuralgic, and other
Nervous Diseases of the Eye," in "Dublin Med. Press," 1841 ; G. Johnson, the article
"Orbit," in "Todd's Cyclopaedia of Anatomy and Physiology.") For the action of the
oblique muscles, see the note on page 501*.
MUSCLES OF THE JAW. 181
MUSCLES OF THE JAW.
The masseter, temporal, and two pterygoid muscles form a group of
muscles of mastication, which may be properly considered together.
The masseter is a thick quadrate muscle, whose fibres are arranged so as to
form two portions differing in size and direction. The superficial part arises
from the anterior two-thirds of the lower border of the zygomatic arch, chiefly
by thick tendons projecting down between the muscular fasciculi, to which
they afford an extensive surface of origin : its fibres proceed downwards and
a little backwards to be inserted into the lower half of the ramus of the jaw,
extending as far as the angle. The fibres of the deep part of the muscle,
much shorter than those of the superficial part, and directed downwards
and forwards, arise from the posterior third of the lower border and from
all the deep surface of the arch, and, becoming united with the superficial
part, are inserted into the upper half of the ramus of the jaw, including the
coronoid process : only the upper and back part of this portion of the muscle
is left uncovered by the superficial portion.
The external surface of the masseter muscle is covered for the most part only by
the skin and fascia ; it is, however, overlapped behind by the parotid gland, and
crossed by its duct ; the branches of the facial nerve and the transverse facial artery
also rest upon it. Its inner surface is towards the buccinator, from which it is separated
by some soft adipose tissue ; it is in intimate contact with the ramus of the jaw, and
covers a nerve and vessels which enter it over the sigmoid notch of that bone.
The temporal muscle (crotaphite Winslow) is fan-shaped, occupies the
temporal fossa, and arises from the whole surface of that fossa, with the
exception of the anterior or malar wall ; it likewise takes origin from the
deep surface of the temporal fascia, which passes down over it to the zygoma,
and some of its posterior fibres arising from this fascia are blended with the
deep fibres of the masseter muscle. The direction of the anterior fibres is
nearly vertical, that of the middle fibres oblique, and that of the posterior
fibres at first horizontal. The fasciculi from this extensive origin converge
as they descend, and all terminate in a tendon, which, emerging from the
interior of the muscle, is implanted into all the inner surface as well as the
anterior border of the coronoid process of the lower jaw-bone, as far down
as the union of the body and ramus of the jaw, where they are blended with
the origin of the buccinator muscle.
The upper part of the muscle is in contact with the temporal fascia; the lower and
anterior part is imbedded in fat continuous with that which lies between the masseter
and buccinator muscles; the insertion of the tendon is mainly concealed by the lower
jaw. Between the muscle and the temporal fossa are the deep temporal arteries and
the temporal nerves, which penetrate its substance. In contact with the deep surface
of the muscle near its insertion the buccal nerve descends, and at the posterior border
of the insertion the masseteric nerve and artery emerge.
The internal pterygoid muscle is related to the inner surface of the ramus
of the jaw, somewhat in the same manner as the masseter is to the outer.
It arises from the pterygoid fossa ; its fibres, tendinous and fleshy, being
attached mostly to the inner surface of the external pterygoid plate, and
that portion of the tuberosity of the palate-bone which is situated between
the pterygoid plates. Thence it is inclined downwards, with a direction
182
MUSCLES OF THE HEAD AND NECK.
backwards and outwards, and is inserted into the angle and the inner
surface of the ramus of the jaw as high as the dental foramen.
Between the external surface of the muscle and the ramus of the maxilla are the
internal lateral ligament and the internal maxillary vessels, with the dental artery
and nerve ; and at its upper part the muscle is crossed by the external pterygoid
muscle. Its inner surface, whilst in the pterygoid groove, is in contact with the
tensor palati muscle ; and lower down it corresponds with the superior constrictor of
the pharynx.
Fig. 158.
Fig. 158. VIEWS OP THE PTERYGOID MUSCLES A, FROM THE OUTER SIDE ; B, FROM
THE INNER SIDE.
1, external pterygoid, placed on the upper head in A, on the lower head in B ; 2,
internal pterygoid the outer surface in A, the inner surface in B.
Fig. 159. VIEW OP A DISSECTION OF THE
LOWER PART OF THE SKULL AND FACE,
FROM BEHIND, DESIGNED TO SHOW THK
ATTACHMENTS OF THE PTERYGOID AND
SOME OTHER MUSCLES (modified from
Bourgery).
a, placed above the transverse section
of the basilar part of the occipital bone,
below which are seen the posterior nares
and palate ; 6, transverse section through
the temporal bone ; c, roof of the mouth ;
d, back of the head and neck of the
lower jaw, above which are seen the
syuovial cavities of the joint divided by
the interarticular fibro-cartilage ; e,
placed below the symphysis menti ; 1, ou
the left side the internal pterygoid muscle
entire ; 1', on the right side the lower part
of the same muscle, of which the middle portion has been removed to show the external
pterygoid ; 2, the lower thick portion of the external pterygoid ; 2', on the right side
points to the upper smaller portion of the muscle, attached in part to the interarticular
plate ; 3, is placed at the side of small portions of the genio-hyoid and genio-hyo-
glossus muscles cut short at their attachment to the lower and upper genial tubercles ; 4,
the attachment of the mylo-hyoid muscle cut short ; 5, indicates the attachment at the
side of the symphysis of the anterior belly of the digastric muscle ; 6, the masseter
muscle descending to the angle of the jaw.
The external pterygoid muscle, occupying the zygomatic fossa, arises by
two fleshy heads placed close together, the superior of which is attached to
SUBMAXILLARY MUSCLES. 183
that part of the external surface of the great wing of the sphenoid bone
which looks downwards, and to the ridge which separates that surface from
the temporal fossa ; while the inferior, which is larger, is attached to the
outer surface of the external pterygoid plate, and to the tuberosities of the
palate and upper maxillary bones. The fibres from both heads pass back-
wards, and being mixed with tendon, converge to be inserted into the fore
part of the neck of the condyle of the lower jaw, and into the inter-articular
fibro-cartilage of the temporo-maxillary articulation.
The internal maxillary artery is placed on the outer surface of this muscle, passing
thence between the heads of origin ; while the buccal nerve issues from between those
heads. The deep surface rests against the upper part of the internal pterygoid muscle,
whose direction it crosses, also the internal lateral ligament of the lower jaw, the
inferior maxillary nerve, and the middle meningeal artery. The upper border is in
contact with the great wing of the sphenoid bone, and is crossed by the deep
temporal nerve and arteries.
ACTIONS. The masseter, temporal, and internal pterygoid muscles are elevators of
the lower jaw, and generally act in concert, bringing the lower into contact with
the upper teeth. The opposite movement of depressing the jaw, not being opposed
by any resisting obstacle, requires less force, and is effected by muscles of much
smaller size, the principal of which is the digastric muscle hereafter described.
The external pterygoid muscle, having the great body of its fibres nearly horizontal,
draws forwards the condyle of the jaw, and, when the muscles of both sides act
together, the lower jaw is protracted so as to make the inferior incisor teeth
project beyond the upper incisors ; but their more usual mode of action is alternately
on the two sides, as in the grinding movement of the molar teeth, in which a variety
of muscular actions are combined. The external pterygoid muscles also, though
chiefly horizontal movers of the jaw, likewise contract in opening the mouth, the
condyles of the jaw being drawn forward in that movement. The masseter and
internal pterygoid muscles assist in protracting the jaw; the temporal alone is a
retractor. The two pterygoid muscles of one side, in advancing one condyle of
the jaw, necessarily throw the teeth towards the opposite side.
SUBMAXILLARY MUSCLES.
A. MUSCLES CONNECTING THE HYOID BONE WITH THE SKULL.
The digastric muscle, extending from the temporal bone to the lower jaw,
consists of two elongated muscular bellies united by an intervening rounded
tendon, which is connected with the hyoid bone. The posterior belly,
which is longer than the anterior, arises from the digastric groove of the
temporal bone, and tapers downwards, forwards, and inwards : the anterior
is attached to a rough depression situated on the lower border of the
jaw-bone, close to the symphysis ; it is less tapering than the posterior
belly, and is directed downwards and backwards. The intervening tendon
is connected with the body and great cornu of the os hyoides by aponeurotic
fibres at right angles to its own, and by the fleshy fibres of the stylo-hyoid
muscle, through which the tendon passes.
The anterior belly, placed immediately beneath the deep cervical fascia, rests on
the mylo-hyoid muscle ; it is connected with its fellow of the opposite side by dense
fascia, and occasionally is united by muscular fibres to it or to the mylo-hyoid muscle.
The posterior belly is covered by the mastoid process and the muscles arising from
that bone, and crosses both carotid arteries and the jugular vein.
184
MUSCLES OF THE HEAD AND NECK.
The stylo-hyoid muscle lies close to the posterior belly of the digastric
muscle, being a little behind and beneath it. It arises from the base of the
styloid process of the temporal bone at the external surface ; and from this
place it inclines downwards and forwards, to be inserted into the os hyoides
at the union of the great cornu with the body. Its fibres are usually
divided into two fasciculi near its insertion, for the transmission of the
tendon of the digastric muscle.
The upper part of the stylo-hyoid muscle lies deeply, being covered by the sterno-
mastoid and digastric muscles, and by part of the parotid gland ; the middle crosses
the carotid arteries ; the insertion is comparatively superficial.
This muscle is sometimes wanting ; occasionally a second is present (stylo-hyoideus
alter, Alb). The position too may be varied it has been found to the inner side
of the external carotoid artery instead of over that vessel. (" The Anatomy and
Operative Surgery of the Arteries," by R. Quain, plate 12, fig. 5.)
Fig. 160. VIEW OF THE SUB-
MAXILLARY MUSCLES AND
THE DEPRESSORS OP THE
HYOID BONE AND LARYNX,
FROM BEFORE. ^
On the right side, the platys-
ma alone has been removed ;
on the left side both the
bellies of the digastric, the
stylo-hyoid, the mylo-hyoid,
the sterno-hyoid, and omo-
hyoid muscles have been re-
moved : a, symphysis ; b,
angle of the lower jaw ; c,
middle of the body of the
hyoid bone ; d, mastoid pro-
cess; e, placed on the front of
the thyroid cartilage, points
to the thyro-hyoid muscle ; f,
upper part of the sternum ;
{/, lateral lobe, and +, isth-
mus of the thyroid gland ;
above +, the front of the
cricoid cartilage covered by
the crico-thyroid muscle ; 1,
posterior belly, 1', anterior
belly, of right digastric muscle ;
2, right mylo-hyoid ; 3, left
genio-hyoid ; 4, hyo-glossus ;
5, stylo-glossus ; 5', a portion of it seen on right side ; 6, stylo-hyoid of the right side ;
7, stylo-pharyngeus of the left side ; 8, placed on the levator scapulae, points to the left
middle constrictor of the pharynx ; 9, placed on the middle scalenus, points to the left
inferior constrictor ; 10, right sterno-hyoid ; 11, placed on the left sterno-thyroid, points
also to the lower part of the right muscle ; 12, placed on the right sterno-mastoid, points
to the upper and lower bellies of the right omo-hyoid.
The mylo-hyoid muscle arises from the mylo-hyoid ridge along the inner
surface of the lower jaw, extending from the last molar tooth to the sym-
pliysis. The posterior fibres are inserted into the body of the os hyoides ;
the rest, proceeding parallel to the fibres behind, join at an angle with those
of the corresponding muscle, forming with them a sort of raphe' along the
middle line, from the symphysis of the jaw to the os hyoides. Thus
the two muscles together form a floor below the anterior part of the mouth
(diaphragma oris of Meyer).
MUSCLES OF THE TONGUE.
185
The lower surface of the mylo-hyoid muscle is covered by the digastric muscle, the
submaxillary gland, and the submental vessels and nerve. The deep surface which
looks upwards and inwards to the mouth, is in contact with the genio-hyoideus and
part of the hyo-glossus and stylo-
glossus muscles, the ninth and gusta-
tory nerves, the sublingual gland, and pj a ^Q^
the duct of the submaxillary gland
The posterior border alone is free and
unattached, and behind it the duct
of the submaxillary gland turns in
passing to the mouth.
Fig 161. A, THE LOWER JAW AND
HYOID BONE, FROM BELOW, WITH
THE MYLO-HYOID MPSCLES AT-
TACHED.
B, THE SAME, FROM BEHIND, WITH THE
MYLO-HYOID AND GENIO-HYOID MUS-
CLES ATTACHED. |
a, the symphysis ; b, the angle of
the lower jaw ; c, the lower border of
the body of the hyoid bone ; d, in B,
the inferior dental foramen and upper
end of the mylo-hyoid ridge : in A,
1, the left, 1', the right mylo-hyoid
muscle from below : in B, 1, the right,
1', the left mylo-hyoid muscle from
above ; 2, the right, 2', the left genio-
hyoid muscle from above; 3, the cut
ends of the attachment of the genio-
glossi muscles to the superior genial
spines.
The genio-hyoid muscle, a narrow muscle resting on the mylo-hyoid, and
in contact with its fellow in the middle line, arises from the inferior of the
two genial tubercles behind the symphysis of the jaw, and is inserted into
the body of the hyoid bone.
It is in contact above with the lower border of the genio-glossus muscle.
ACTIONS. The genio-hyoid and mylo-hyoid muscles draw the hyoid bone upwards
and forwards, as happens in the first stage of deglutition. The stylo-hyoid muscle
draws it upwards and backwards, and comes into action in raising the pitch of the
voice. The anterior belly of the digastric muscle acts by itself like the genio-
hyoid, and the posterior half like the stylo-hyoid ; but when both bellies act
together they are capable of producing two movements, in one of which, when the
lower jaw is fixed, the hyoid bone is elevated, and in the other, when the hyoid
bone is held downwards by the depressing muscles, the digastric muscle opens the
mouth by depressing the lower jaw.
B. MUSCLES OF THE TONGUE.
The tongue is a muscular organ attached posteriorly to the hyoid bone,
and inferiorly to the lower jaw. It is composed partly of fibres peculiar to
itself the intrinsic muscles, which will be noticed in another place ; partly
of muscles arising from neighbouring parts ths extrinsic muscles about to
be described.
The fjenio-glossus or genio-hyo-glossus muscle is fan-shaped, and is placed
vertically in contact with its fellow close to the mesial plane. It arises by
186
MUSCLES OF THE HEAD AND NECK.
a short tendon from the superior genial tubercle behind the symphysis of
the jaw : from this its fibres diverge and are inserted in an extensive range,
viz., those which are most inferior into the body of the hyoid bone, and a
few into the side of the pharynx ; those which are most superior into the
tip of the tongue ; and the intermediate fibres into its whole length,
diverging transversely in its substance.
The external surface is in contact with the lingualis inferior, hyo-glossus and stylo-
glossus muscles, the sublingual gland, the ranine vessels, and the nerves of the tongue.
Fig. 162.
Fig. 162. SKETCH OP A PART
OF THF LEFT SIDE OF THE
SKULL, THE RIGHT SIDE OF
THE BODY OF THE LOWER JAW,
AND THE TONGUE, HYOID
BONE, LARYNX, AND TRACHEA,
SHOWING THE EXTRINSIC
MUSCLES OF THE TONGUE,
&o. 4
a, external pterygoid pro-
cess ; b, styloid process ; c,
section of the symphysis of the
lower jaw; d, front of the
body of the hyoid bone ; c,
hyoid cartilage ; /, front of the
cricoid cartilage ; between d
and e, the thyro-hyoid mem-
brane and ligament ; g, isthmus
of the thyroid gland in front
of the trachea; 1, left stylo-
glossus muscle ; 2, stylo-hyoid ;
3, stylo-pharyngeus ; 4, cut
edge of the mylo-hyoid ; 5,
genio-hyoid ; 6, genio-hyo-glos-
sus; 7, hyo-glossus; 8, lingua-
lis inferior ; 9, part of the supe-
rior constrictor of the pharynx ;
10, back part of the middle
constrictor; 11, inferior con-
strictor ; 12, upper part of the
oesophagus; 13, crico-thyroid
muscle.
The hyo-glossus is a flat
quadrate muscle, arising
from the whole length of
the great cornu of the hyoid bone, from the lateral part of the body of that
bone, and from the small cornu ; the fibres arising from those three sources
(formerly distinguished as cerato-glossus, basio-glossus, and chondro-glossus
respectively Albums) pass upwards to be inserted into the side of the
tongue, blended with the stylo-glossus and palato-glossus muscles.
The hyo-glossus is concealed by the digastric and mylo-hyoid muscles, except at its
posterior inferior angle : the deep part of the submaxillary gland rests on its surface,
and it is crossed from below upwards by the hypoglossal nerve, the Whartonian duct,
and the gustatory nerve, It covers the genio-gloseus and the origin of the middle
constrictor of the pharynx, together with the lingual artery and glosso-pharyngeal
The stylo- glossus, the shortest of the three muscles which spring from the
styloid process, arises from that process not far from its point, and from the
MUSCLES OF THE PHARYXX.
187
the greater number of
passing forwards slightly
Fig. 163.
stylo-maxillary ligament, to which in some
its fibres are attached by a thin aponeurosis
downwards, it is inserted
along the side and under part
of the tongue as far as the tip,
its fibres decussating, and be-
coming blended with those of
the hyo-glossus and palato-
glossus muscles.
This muscle lies deeply beneath
the parotid gland, and is crossed
by the gustatory nerve. It arises
occasionally from the inner side of
the angle of the lower jaw ; and
cases have been observed in which
it was altogether absent.
Fig. 163. VIEW OB- PART OE THR
LEFT SIDE OF THE HEAD AND
THROAT, TO SHOW THE DEEP MUS-
CLES OF THE CHEEK, PHARYNX,
&0. (modified from Cloquet). ^
The pharynx has been distended
by stuffing, a, external pterygoid
process ; 6, styloid process, with
short portions of the three styloid
muscles attached ; c, body of the
lower jaw, which has been divided
at the place where the pterygo-
maxillary ligament + is attached ;
d, body of the hyoid bone; e,
thyroid cartilage ; /, cricoid carti-
lage ; g, interval between the first
and second ring of the trachea ; 1,
outer part of the orbicularis oris muscle ; 2, buccinator ; 3, superior constrictor of the
pharynx ; 4, middle constrictor ; 5, inferior constrictor ; 6, oesophagus ; 7, points by
three lines to the lower parts of the stylo-glossus, stylo-hyoid, and stylo-pharyngeus
muscles respectively ; 8, mylo-hyoid ; 9, hyo-glossus, of which a small part is removed
posteriorly to show the attachment of the middle constrictor ; 10, thyro-byoid.
ACTIONS. The genio-glossus muscle has a complicated action, one part protruding
and another retracting the tongue, while a third depresses the middle portion of the
organ. Protrusion is effected by contraction chiefly of its posterior, and retraction
by contraction of its anterior fibres, and the middle part, or nearly the whole muscle,
acts as the depressor. In deglutition the stylo-glossus muscle raises the sides of the
tongue spasmodically backwards and upwards, while the hyo-glossus opposes that
action. In other circumstances the first muscle assists in forming a hollow, while
the second tends to producing a convexity in the dorsum of the tongue.
MUSCLES OF THE PHARYNX AND SOFT PALATE.
THE PHARYNX, the dilated superior part of the alimentary tube, extending
from the base of the skull to the oesophagus, presents at the sides and pos-
teriorly a continuous wall, in great part formed and supported by distinct
muscles resting in front of the vertebral column, and is open in front
towards the nasal cavity, the mouth, and the larynx,
The constrictors of the pharynx are three thin expanded muscles which
invest the pharyngeal wall, overlapping one another upwards, so that the
lowest is most superficial.
188
MUSCLES OF THE HEAD AND NECK.
The inferior constrictor arises from the side of the cricoid cartilage, and
from the oblique lateral ridge and upper and lower borders of the thyroid
cartilage, and curves backwards, expanding as it proceeds, and unites with
its fellow in the middle line behind the pharynx. The direction of the
inferior fibres is horizontal, concealing and overlapping the commencement
of the oesophagus ; the rest ascend with increasing degrees of obliquity, and
cover the lower part of the middle constrictor.
The outer surface of the muscle is in contact at the side of the larynx with the
thyroid body, the carotid artery, and the sterno-thyroid muscle ; and from this last,
where the two muscles meet on the thyroid cartilage, some fibres are continued into the
constrictor. The two laryngeal nerves pass inwards to the larynx, close respectively
to the upper and lower margins of this constrictor the upper being interposed between
it and the middle constrictor, the lower between it and the oesophagus.
The inferior constrictor was described by the older anatomists as two muscles which
received various names, the most appropriate of these being thyro-pharyngeus and
crico-pharyngeus. In some animals they are found quite distinct from one another.
F5g 164. Fig. 164. VIEW OP
THE MUSCLES OF
THE PHARYNX, &o.
FROM BEHIND (after
Bourgery.)
The back part of
the skull, the ver-
tebral column and
back parts of the
ribs are removed, a,
cut surface of the
basilar process ; &,
the clavicle ; c, the
first rib ; d, the
ramus of the lower
jaw ; e, posterior ex-
tremity of the great
cornu of the byoid
bone ; /, posterior
surface of the manu-
brium of the ster-
num ; 1, superior
constrictor muscle of
the pharynx ; above
it, the fibrous mem-
brane which closes
the pharynx; 2, mid-
dle constrictor ; 2',
a dotted line, indi-
cating the direction
of the lower part of
the muscle ; 3, the
inferior constrictor ;
4, oesophagus ; 5, in-
ternal pterygoid ; 6,
stylo-glossus ; 7, pos-
terior belly of the
digastric ; 8, a portion of the stylo-hyoid surrounding the tendon of the digastric ; 9,
sterno-mastoid ; 10, upper belly of the omo-hyoid ; 11, sterno-thyroid muscle.
The middle constrictor arises from the upper part of the great cornu of
the os hyoides, from the smaller cornu, and from the stylo-hyoid ligament :
its fibres, diverging greatly, pass back to the middle line of the pharynx behind,
MUSCLES OF THE PHARYNX AND PALATE. 189
the lower fibres ID dining downwards beneath the inferior constrictor, the
highest ascending and overlapping the superior constrictor, and the interme-
diate fibres running transversely.
This muscle is separated from the superior constrictor by the stylo-pharyngeus
muscle and the glosso-pharyngeal nerve, while between its origin and that of the
inferior constrictor the superior laryngeal nerve pierces the thyro-hyoid membrane.
Fibres of the middle constrictor have been observed to arise from the body of the
os hyoides, and the thyro-hyoid ligament (syndesmo-pharyngeus of Douglas), and a
few are frequently continued into it from the genio-hyo-glossus muscle. The two
middle constrictors have been found connected behind to the base of the skull by a
fibrous band (Albiiius).
The superior constrictor arises by fibres attached in series from below
upwards, a few to the side of the tongue, and others to the mucous mem-
brane of the mouth, to the extremity of the mylo-hyoid ridge of the jaw, to
the ptery go- maxillary ligament which separates this muscle from the bucci-
nator, and to the lower third of the internal pterygoid plate. From these
different points the fibres of the muscle curve backwards, and are mostly
blended with those of the corresponding muscle aloug the middle line, a
few ending posteriorly in the aponeurosis which fixes the pharynx to the
base of the skull. The upper margin curves round the levator palati inollis
and the Eustachian tube ; and the space intervening between this concave
margin of the constrictor and the base of the skull is closed by fibrous
membrane.
In contact with the outer surface of this muscle are the internal carotid artery, with
the eighth and other larger nerves ; the middle constrictor, which overlaps a consider-
able portion ; and the stylo-pharyngeus, which descends to the pharynx between the
two constrictors. It conceals the palato-pharyngeus and the tonsil, and is lined by
mucous membrane.
The stylo-pharyngeus, larger and longer than the other styloid muscles,
arises from the inner surface of the styloid process, near the root, and pro-
ceeding downwards and inwards to the side of the pharynx, passes under
cover of the middle constrictor muscle, where it detaches some fibres to the
constrictors, and, gradually expanding, is connected with the palato-pharyn-
geus muscle, and ends in the superior and posterior borders of the thyroid
cartilage.
The external surface of this muscle is, in the upper part of its extent, in contact
with the styloid process, the stylo-hyoideus muscle, and the external carotid artery ;
in the lower, with the middle constrictor of the pharynx. Internally it rests on the
internal carotid artery and jugular vein; but more inferiorly it is in contact with the
mucous membrane of the pharynx. The glosso-pharyngeal nerve is close to the
muscle, and crosses over it in turning forwards to the tongue.
The salpingo-pharyngeus (Santorini) is a small muscle, which, arising from
the Eustachian tube, descends in the interior of the pharynx towards its
back part, and, after joining with the palato-pharyngeus, is lost in the
muscular structure of the cavity. It is often indistinct, and is frequently
absent.
THE SOFT PALATE (velum pendulum palati) is a movable cuitain, continued
backwards from the hard palate. It presents posteriorly a free pendulous
margin, prolonged in the middle into a conical process, the uvula, and at
each side into two prominent curved lines, the anterior of which, the anterior
pillar of the fauces, descends to the side of the tongue, while the posterior
line, the posterior pillar of the fauces, extends into the pharynx : between the
190
MUSCLES OF THE HEAD AND NECK.
two is lodged the tonsil. The constricted passage between the anterior pillars,
leading from the mouth to the pharynx, is called the isthmus of the fauces.
The soft palate is acted on by five pairs of elongated muscles, two superior,
one in the middle, and two inferior. Of the two inferior pairs of muscles,
one is common to the palate and tongue, the other to the palate and
pharynx.
The palato-glossus or constrictor isthmi faucium occupies the anterior
pillar of the fauces. Superiorly it is anterior to all the other muscles of the
velum, and its fibres are continuous with those of its fellow of the opposite
side ; inferiorly, it is lost on the side of the tongue.
Fig. 165. Fig- 165. DIAGRAMMATIC VIEW OP THE
MUSCLES IN THE ANTERIOR WALL AND
SJDESOF THE PHARYNX, FROM BEHIND. J
The posterior wall of the pharynx has
been divided by a vertical incision in
the middle line, and the cut edges drawn
to the side so as to expose the nasal,
buccal, and laryngeal openings into the
pharynx, a, is above the cut surface of
the basilar part of the occipital bone,
and below that are the posterior nares ;
b, upon the cut petrous bone, points by
a line to the cartilage of the Eustachian
tube of the right side ; c, the back of
the ramus of the lower jaw ; d, the
posterior border of the thyroid cartilage ;
e, middle of the upper part of the cricoid
cartilage; /, base of the tongue in the
buccal aperture above the epiglottis ; g,
lower end of the cavity of the pharynx
leading down into the gullet ; 1 , supe-
rior constrictor of the pharynx seen from
within, and part of the middle con-
strictor ; 2, palato-pharyngeus descend-
ing to its insertion in the pharynx and
thyroid cartilage ; 2', the lower part
of the same muscle, on the right side,
the upper having been removed ; 3,
placed on the internal pterygoid muscle,
points to the levator palati ; 4, the circumflexus palati muscle on the right side descend-
ing from the navicular fossa, and winding round the pulley-like groove of the hamular
process into the palate; 5, the retractor or azygos uvulae muscles; above e, the transverse
arytenoid muscle, and below it on each side the posterior crico-arytenoid muscle.
The palato-pharyngeus, occpyuing the posterior pillar of the pharynx,
arises in the soft palate by fibres connected with those of the opposite side,
and passing partly above and partly below the levator palati and azygos
muscles. As the muscle descends it becomes greatly expanded, and its
fibres are found extended from the posterior cornu of the thyroid cartilage,
back to the middle line of the pharynx posteriorly.
The azygos uvula (Morgagni) so called from having been supposed to be
a single muscle, consists of two slips arising, one on each side of the middle
line, from the tendinous structure of the soft palate, and, sometimes, from
ihe spine of the palate-plate, and descending into the uvula. The two slips
are separated by a slight interval above, and unite as they descend.
The levator palati arises from the extremity of the petrous portion of the
temporal bone, in front of the orifice of the carotid canal, and from the
cartilaginous part of the Eustachian tube. Approaching the middle line as it
MUSCLES DEPRESSING THE HYOID BONE. 191
passes downwards and forwards, it is inserted aponeurotically into the pos-
terior part of the soft palate, and meets its neighbour of the opposite side.
In its upper part it is placed above the concave margin of the superior
constrictor.
The circumflexus or tensor palati arises from the navicular fossa at the
root of the internal pterygoid plate, from the outer side of the Eustachian
tube, from the spine of the sphenoid, and the edge of the tympanic plate of
the temporal bone. It descends perpendicularly, resting on the internal
pterygoid plate, between it and the internal pterygoid muscle, and ends in
a tendon which, winding round the hamular process, lubricated by a bursa,
extends horizontally inwards, and terminates in the forepart of the aponeu-
rosis of the soft palate and the posterior border of the palate bone.
ACTIONS. The muscles of the pharynx and soft palate are so arranged as to
accomplish, in conjunction with those of the tongue and hyoid bone, the action of
deglutition that is to say, the propulsion of food into the oesophagus without any
portion being permitted to pass into the nasal cavity or larynx. While the tongue
near the fauces is thrown upwards and backwards by the stylo-glossi muscles, and the
larynx is drawn upwards and forwards under it by muscles attached to the hyoid-bone,
and by the stylo-pharyngeus muscle, so as to be both closed by the epiglottis and
overlapped by the tongue, the palato-glossi muscles constrict the fauces and shut off
the bolus from the mouth. The soft palate is raised and made tense by its superior
muscles ; the palato-phary ngei, being approximated, nearly touch one another (the uvula
lying in the small interval between them), and prevent the passage of the food towards
the upper part of the pharynx or the posterior nares, while at the same time they form
an inclined surface for its guidance into the lower part of the pharynx. The food
being thus thrown into the grasp of the constrictors of the pharynx, those muscles
contract from above downwards and force it into the tube of the gullet below.
MUSCLES DEPRESSING THE HYOID BONE.
The sterno-hyoid muscle, a flat band of longitudinal fibres, arises variously,
from the sternum and the posterior sterno-clavicular ligament, from the
clavicle and that ligament, or from the clavicle only, and occasionally, to a
small extent, from the cartilage of the first rib. It is inserted into the lower
border of the body of the hyoid bone.
The muscle is concealed below by the sternum and the sterno-mastoid, higher
up by the skin and fascia only ; it lies on the sterno-thyroid and thyro-hyoid
muscles, which it partly covers. The inner border approaches that of the corre-
sponding muscle towards the middle of its extent, but is separated from it by a
slight interval superiorly, and by a larger interval near the sternum ; the outer
margin is in contact with the omo-hyoid near the os hyoides. The muscular fibres
are, in many cases, interrupted by a transverse tendinous intersection.
The sterno-thyroid, broader and shorter than the preceding muscle, behind
which it lies, arises from the thoracic surface of the first bone of the sternum,
lower down and more internally than the sterno-hyoid muscle, and ascends,
diverging a little from its fellow, to be inserted into the oblique line on
the ala of the thyroid cartilage.
The greater part of its anterior surface is concealed by the sternum and the sterno-
hyoid muscle, as well as by the sterno-mastoid. By its deep surface it rests on
the innominate vein, the lower part of the common carotid artery, the trachea, and
the thyroid body. The inner margin is contiguous to the muscle of the other side in
the lower part of the neck. The median incision in the operation of tracheotomy is
made between the two muscles.
This muscle is often partly crossed by transverse or oblique tendinous lines. At
192
MUSCLES OF THE HEAD AND NECK.
the upper extremity a few fibres are often found to blend with the thyro-hyoid muscle
and the inferior constrictor of the pharynx.
Fig. 166. Fig. 166. VIEW OP THE
StTBMAXILLARf MUSCLES
AND THE DEPRESSORS OP
THE HyoiD BONE AND
LARYNX, FROM BEFORE.
The explanation of the
references to the upper
parts of the figure is given
at p. 184. c, middle of
the body of the hyoid bone ;
d, mastoid process; e, placed
on the front of the thyroid
cartilage, points to the thy-
ro-hyoid muscle ; /, upper
part of the sternum ; g,
lateral lobe of the thyroid
gland ; +, its isthmus,
above which is the cricoid
cartilage covered by the
crico-thyroid muscle ; 8,
placed on the levator sca-
pulae, points to the left
middle constrictor of the
pharynx ; 9, placed on the
middle scalenus, points to
the left inferior constrictor ;
10, right sterno-hyoid ; 11,
placed on the left sterno-
thyroid, points also to the
lower part of the right muscle ; 12, placed on the right sterno-mastoid, points to the
upper and lower bellies of the right omo-hyoid.
The thyro-Tiyoid muscle is continued upwards from the preceding ; it
arises from the oblique line on the ala of the thyroid cartilage, and is
inserted into the lower border of the body and great cornu of the hyoid
bone, near the place where these unite.
This muscle is concealed by the sterno-hyoid and omo-hyoid, and rests on the ala
of the thyroid cartilage, and on the thyro-hyoid membrane. Between that membrane
and the muscle, the superior laryngeal nerve and artery are placed before entering the
larynx.
The omo-hyoid is a long ribbon-shaped muscle, consisting of two bellies
united by an intervening tendon. It arises from the upper border of the
scapula, near the suprascapular notch, and occasionally from the ligament
which crosses the notch. Thence it extends forwards and only slightly
upwards, across the root of the neck, till it enters beneath the sterno-mas-
toid muscle, and then, curving rapidly, it ascends nearly vertically, to be
inserted into the lower border of the body of the hyoid bone. The ten-
don which divides the muscle is placed beneath the sterno-mastoid muscle,
and varies much in length and form in different bodies. The tendon is
enclosed within the deep cervical fascia, which, after forming a sort of
sheath for it, is prolonged downwards and becomes attached to the sternum
and the cartilage of the first rib ; and by this means, as also by fascia
investing the posterior belly and descending to the clavicle, the muscle is
maintained in its curved position.
FLEXOR MUSCLES OF THE XECK. 193
At its scapular origin the muscle is covered by the trapezius, in the middle of its
course by the sterno-mastoid, and at its upper part by the platysma ; it crosses the
scaleni muscles, the cervical nerves, the sheath of the common carotid artery and
jugular vein, and the sterno-thyroid and thyro-hyoid muscles.
The muscle occasionally is attached to the clavicle instead of the scapula, arising
from the former bone about its middle, and in such a case the posterior belly is
absent. One instance has been recorded (R. Quain) in which the posterior belly alone
was present, and was connected to the hyoid bone by a band of fascia. The muscle
has likewise been observed double, one slip being attached to the clavicle and the
other to the normal place of origin on the scapula.
ACTIONS. While the sterno-hyoid and omo-hyoid muscles act only as depressors of
the hyoid bone, and the sterno-thyroid as a depressor of the larynx, the sterno-thyroid
muscle, being a direct depressor of the thyroid cartilage, may draw down the hyoid
bone when it acts in conjunction with the thyro-hyoid : the latter muscle elevates the
larynx when the hyoid bone is fixed. In the act of swallowing, the hyoid bone and
thyroid cartilage pass suddenly upwards and forwards, and their natural position is
restored by the action of the muscles under consideration, the bone moving in the
direction of the omo-h}'oid muscles. In the utterance of low notes the larynx and
hyoid bone descend below the natural level, in the direction in which the sternal
muscles pull ; while in the utterance of high notes there is little elevation of the hyoid
bone, but the larynx is raised by the action of the thyro-hyoid muscles.
FLEXOR MUSCLES OF THE NECK.
The sterno-cleido-mastoid or sterno-mastoid muscle is attached inferiorly
in two parts to the anterior surface of the sternum and the inner third of
the clavicle. The sternal attachment is thick and rounded, tendinous in
front and fleshy behind. The clavicular portion, separated from the sternal
by a narrow interval, is flat, and is composed of fleshy and tendinous fibres.
Those two portions become blended together about the middle of the neck
into a thick and prominent muscle, which, extending upwards and back-
wards, is attached superiorly to the anterior border and external surface of
the mastoid process, and from thence backwards into a rough ridge of the
temporal, and by a thin aponeurosis into the outer part of the superior
curved line of the occipital bone.
This muscle is covered for more than the middle three-fifths of its extent by
the platysma. It is also crossed by the external jugular vein, and by the ascending
superficial branches of the cervical plexus of nerves. It rests on part of the sterno-
hyoid and sterno-thyroid muscles, and crosses the omo-hyoid muscle ; in the middle
part of the neck it covers the cervical plexus and the great cervical vessels, and in the
upper part, the digastric and stylo-hyoid muscles : it is pierced by the spinal accessory
nerve.
The sterno-cleido-mastoid is occasionally described as two muscles, under the names
sterno-mastoid and cleido-mastoid. Normally the fibres of the clavicular part run
upwards for some distance internally to those of the sternal part before finally
blending with them. The muscle varies much in breadth at the lower end, the
variation being due altogether to the clavicular part, which is sometimes as
narrow as the sternal tendon, while in other instances it extends for three
inches along the clavicle. This part of the muscle may likewise, when broader than
usual, be divided into several slips separated by intervals near the clavicle. A band
of muscular fibres has, in a few instances, been found reaching from the trapezius to
this muscle over the subclavian artery ; and the margins of the two muscles have
been observed in contact. In animals without a clavicle the cleido-mastoid muscle is
continued into the clavicular part of the great pectoral muscle, thus forming a
mastoido-humeral muscle.
The scalenus anticus muscle is attached superiorly to the anterior
o
194
MUSCLES OF THE HEAD AND NECK.
tubercles of the transverse processes of the third, fourth, fifth, and sixth
cervical vertebra, and inferiorly by a thick flattened tendon to a rough part
of the inner border and upper surface of the first rib.
F.?g. 167.
Fig. 167. SUPERFICIAL AM> DEEP VIEW OF THE MUSCLES OP THE HEAD AND NECK, FROM
BEFORE. ^
The explanation of the references to the cranium and face will be found at page 172 :
C, body of the hyoid bone ; e, subclavian groove of the first rib, above which the cut end
of the subclavian artery is shown; /, glenoid head of the scapula ; 15, sterno-mastoid
muscle ; 15', its clavicular portion ; 16, sterno-hyoid ; 17, posterior, and 17', anterior
belly of the omo-hyoid ; 17", portion of the deep fascia, which forms a loop holding down
the muscle by its central tendon ; 18, on the sternum at the interclavicular notch, points
by lines upwards to the lower part of the sterno-thyroid muscles ; 19, thyro-hyoid ; 20,
part of the constrictors of the pharynx ; 22, clavicular part of the trapezius ; 25, levator
scapulae; 26, scalenus posticus ; 27, scalenus medius; 28, scalenus antieus ; 29,
clavicular, and 29', pectoral portion of the pectoralis major ; 30, pectoralis minor.
FLEXOS MUSCLES OF THE NECK.
195
This muscle is placed deeply : in its lower part it is crossed by the posterior belly
of the omo-hyoid muscle, and in its whole length it is traversed by the phrenic nerve
passing obliquely from above downwards and inwards. The subclavian vein and
artery pass respectively in front and behind its inferior attachment. The nerves
of the brachial plexus emerge from behind its outer border above the subclavian
artery. The rectus capitis anticus major arises on its inner side, the ascending
cervical branch of the inferior thyroid artery lies in the groove between that muscle
and the scalenus, and in front is the internal jugular vein.
The scalenus medius is attached superiorly to the posterior tubercles of
the transverse processes of the last six cervical vertebrae ; and inferiorly
to a rough elevation on the first rib, extending for an inch and a half
forwards from the tubercle.
In front of this muscle, between it and the anterior scalenus, are the cervical
nerves and the subclavian artery ; behind it are the posterior scalenus and levator
anguli scapulae muscles. It is sometimes attached to the transverse process of the
atlas.
The scalenus posticus, smaller than the other scaleni muscles, is attached
above by two or three small tendons to the transverse processes of
as many of the lowest cervical vertebrae, and inferiorly by an aponeu-
rotic tendon to the second rib, in front of the attachment of the
levator costae.
Fig. 168. VIEW OP THE DEEP
MUSCLES COKNECTED WITH
THE UPPER PART OP THE
VERTEBRAL COLUMN IN
FRONT.
l * '
The skull has been removed
in front of the basilar and
mastoid processes, together
with the sternum and anterior
parts of the first and second
ribs, a, cut surface of the
basilar process ; 6, transverse
process of the atlas ; e, trans-
verse process of the seventh
cervical vertebra ; d, body of
the first, d', of the fourth dor-
sal vertebra ; e, first, and e',
second rib ; 1, rectus capitis
anticus major muscle ; 2, rec-
tus capitis anticus minor ; 3,
middle part, 3', upper part, and
3", lower part of the longus colli ;
4, rectus lateralis; 4', first
pair, and 4", second pair of
intertransversales ; 5, scalenus
anticus of the right side ; 5',
the tendon of attachment to
the first rib on the left side,
the rest of the muscle having
been removed ; 6, scalenus
medius of the right side ; 6',
lower portion of the correspond -
ing muscle of the left side ; 7,
scalenus posticus, its superior
attachments shown upon the left side ; 8, upper part of the levator scapulae drawn out
from its vertebral attachments ; 9, spleuius colli, shown in the same manner.
o 2
196 MUSCLES OF THE HEAD AND NECK.
The scaleni muscles are subject to some amount of variation, both in the number of
their points of attachment, and in the arrangement of their fibres. A slip from the
scalenus anticus sometimes passes behind the subclavian artery.
The rectus colitis anticus major arises from the tubercles of the trans-
verse processes of the third, fourth, fifth, and sixth cervical vertebrse by
tendinous slips, its origin corresponding in extent to the superior attachment
of the anterior scalenus muscle : it is inserted into the basilar process of
the occipital bone, a little in front of the foramen magnum. The muscles of
opposite sides converge as they ascend, and their mesial fibres are longest.
The anterior surface of the rectus eapitis anticus major supports the pharynx,
the sympathetic and vagus nerves, and the great cervical vessels. The posterior
surface rests upon part of the longus colli and the rectus anticus minor.
The rectus eapitis anticus minor, under cover of the preceding, arises
from the anterior arch of the atlas, and slightly from the root of its
transverse process ; it is inserted into the basilar process, between the
margin of the foramen magnum and the preceding muscle, half an inch from
its fellow.
The rectus eapitis lateralis is a short thick muscle arising from the upper
surface of the anterior division of the transverse process of the atlas, and
inserted into the rough surface beneath the jugular eminence of the occi-
pital bone. It completes the series of intertransversales muscles.
The anterior surface of this muscle is in contact with the internal jugular vein, the
posterior with the vertebral artery.
The longus colli muscle rests on the front of the vertebral column from
the atlas to the third dorsal vertebra : it consists of three sets of fibres, of
which two are oblique, and one vertical, a. The superior oblique portion
arises, by a narrow tendinous process, from the anterior tubercle of th&
body of the atlas, and is inserted into the fore part of the transverse
processes of the third, fourth, and fifth cervical vertebrae, b. The inferior
oblique, the smallest part of the muscle, extends obliquely inwards from
the transverse processes of the fifth and sixth cervical to the bodies of the
first two or three dorsal vertebrse. c. The vertical part, connected by its
extremities with the other divisions, is attached superiorly to the bodies of
the second, third, and fourth cervical vertebrse, and inferiorly to the bodies
of the three lower cervical and two or three upper dorsal vertebrse.
ACTIONS. The sterno-cleido-mastoid muscles, and in a less degree the scaleni
muscles, bend forwards the head and neck towards the sternum. The sterno-mastoid
muscles, when acting in concert with the extensor muscles of the head, assist in the
extension, and project the chin. When the sterno-mastoid muscle of one side only
is in action, the head, while it is slightly flexed, is inclined laterally to the side on
which the muscle contracts, and rotation is produced, by which the face, and especially
the chin, is directed towards the opposite side. This is the position which occurs in
wry-neck, depending upon an unequal action of the opposite sterno-mastoid muscles.
The scalene muscles, when the vertebral column is iixed, act as elevators of the ribs,
and by many are considered as constant aids in the movement of inspiration. It
seems certain that when the head is fixed the sterno-mastoid muscles also assist in
forcible inspiration by the elevation of the sternum and clavicles.
FASCIJE OF THE HEAD AND NECK.
The SUPERFICIAL FASCIA is little developed on the head and neck, and is
in gretit measure blended with structures described under other names. A
DEEP CERVICAL FASCIA. 197
layer of considerable firmness intervenes between the aponeurosis of the
occipito-frontalis muscle and the skin, uniting them together : from the
surface of the occipital part of the muscle it becomes continuous with a
superficial covering of the posterior muscles of the neck, and on each side
of the epicranial aponeurosis it descends over the temporal fascia, and contains
between its laminae the external muscles of the ear, with the superficial
temporal vessels and nerves.
In the face, the fibres of the superficial muscles are frequently so much
incorporated with the skin, that in many parts there is no distinct intervening
layer of superficial fascia ; and over most of the face the subcutaneous fat
breaks up the fascia to a great extent. On the side of the neck, where a
representative of the superficial fascia is found in the tissue containing the
platysma myoides muscle, it is thin, and has embedded in it the external
jugular vein and some superficial nerves.
The DEEP FASCIAE of the head and neck deserve special attention, as they
give investments of considerable strength, and serve to mark the separation
between several important organs.
The temporal fascia is a structure of an aponeurotic nature, which covers
the temporal muscle above the zygoma, and gives extensive attachment to
its fibres of origin. It springs infeiiorly from the upper border of the
zygomatic arch, and is attached in the rest of its circumference to the
posterior border of the malar bone and to the temporal ridge on the
frontal, parietal, and temporal bones. It is divided below into two layers,
one of which is attached to the outer and the other to the inner surface of
the zygoma ; and in this situation there is deposited between its layers a
quantity of fat, the absorption of which is one cause of the hollowness of
the temples in emaciated persons. This dense fascia is separated from the
integuments by the layer of thin membrane descending from the epicranial
aponeurosis, and by the auiicular muscles; and from the temporal muscle
below, by a deeper layer of fat.
The cervical fascia (named also proper or deep cervical) passes forwards
from the anterior border of the trapezius muscle over the sides and front
of the neck beneath the platysma myoides. Posteriorly it is continuous with
the layers of connective tissue with which the trapezius and deeper muscles
are invested ; it extends over the posterior triangle of the neck, viz., the
space bounded by the trapezius and sterno-mastoid muscles and the clavicle :
at the posterior border of the sterno-mastoid it divides into two layers,
which form an investment for that muscle ; these unite again at the anterior
border into a membrane which passes forwards across the middle line, and
covers the area bounded by the middle line, the border of the jaw, and the
sterno-mastoid muscle, and called the anterior triangle, In the posterior
triangle the fascia is attached iiiferiorly to the clavicle, and near that bone
is perforated by the external jugular vein, which in the previous part of
its course lies superficial to the membrane. In the anterior triangle
it is bound superiorly to the border of the jaw in front, and further back is
continued over the masseter muscle (masseteric fascia), and the parotid gland,
which it closely invests (parotid fascia) ; it likewise sends upwards a pro-
cess on the posterior and deep surfaces of the parotid gland ; and a strong
band of this process, known under the name of the stylo-maxillary ligament,
extends from the styloid process to the angle of the jaw, so as to keep tha
parotid and submaxillary glands distinct, even although one or both of them
may be greatly enlarged.
In the front of the neck the fascia is attached to the hyoid bone, arid, becom-
198 MUSCLES OF THE UPPER LIMB.
ing stronger as it descends, it splits, a little below the level of the thyroid
body into two distinct layers. Of these the more superficial and weaker,
guided by the sterno-mastoid muscles, is fixed to the sternum and the
interclavicular ligament ; whilst the stronger layer, lying under the former,
and closely covering the sterno-hyoid and sterno-thyroid muscles, is
attached to the deeper surface of that bone. These layers materially
assist in closing the cavity of the chest, above the sternum : between them
there exists a quantity of loose connective tissue and fat, and sometimes
a small lymphatic gland.
Continuous with the deeper of those two layers, a deep layer is found
likewise in the posterior triangle, investing the posterior belly of the omo-
hyoid muscle, and binding it down to the clavicle and first rib. Still deeper
than the processes now described is a layer which lies behind the depressor
muscles of the larynx, investing the thyroid body, and extending thence on
the trachea and large vessels at the root of the neck down to the fibrous
layer of the pericardium .
Continuous with the deep processes of the cervical fascia is the common
sheath of the large cervical blood-vessels, an envelope of fascia enclosing the
carotid artery and jugular vein with the pneumogastric nerve. A thin
fibrous septum intervenes between the artery and vein, thus completing a
separate sheath for each.
The layer of fascia descending on the prevertebral muscles, and inter-
vening between them and the pharynx and oesophagus, is called the pre-
vertebral fascia.
MUSCLES OF THE UPPER LIMB.
Between different parts of the head and trunk on the one hand, and the
shoulder and humerus on the other, certain muscles pass which attach the
upper limb to the body, and which, though situated mainly on the trunk,
and often described along with its muscles, have so intimate a connection,
both in their structure and uses, with the limb, that they may with greater
propriety be treated of along with the muscles of that part. The muscles
referred to are, posteriorly, the trapezius, latissimus dorsi, levator anguli
scapulae, and the rhomboidei ; and, anteriorly, the two pectoral muscles, the
subclavius, and the serratus magnus. Along with these might also be
mentioned the clavicular part of the sterno-cleido-mastoid muscle and the omo-
hyoid ; but as these last have important relations with parts situated in the
neck, they are more conveniently described among the muscles of that region.
Fig. 169. SUPERFICIAL MUSCLES OP THE TRUNK, SHOULDER AND HIP, VIEWED FROM
BEHIND.
a, external occipital protuberance ; b, acromion of the scapula ; e, crest of the ilium ;
1, trapezius ; 1', oval tendon of the two muscles in the upper dorsal and lower cervical
region ; 1", triangular tendon of insertion ; 2, latissimus dorsi ; 2', 2', its costal origins
and its direct origin from the crest of the ilium ; 1, 2', c, the superficial layer of the
lumbar aponeurosis ; 3, sterno-mastoid ; 4, deltoid ; 5, infraspinatus ; 6, teres minor ;
7, teres major ; 8, rhomboideus major ; below this on the left side is seen a triangular
space bounded by the rhomboid, trapezius, and latissimus dorsi muscles, in which, when
the arm is depressed, as on the right side, a part of the seventh rib is usually felt; on the
left side, the arm and shoulder being elevated, the space is enlarged so as to show a part
of the sixth and seventh ribs ; 9, back part of the external oblique muscle of the
abdomen; between 9 and 2', a small part of the internal oblique ; 10, part of the gluteus
medius covered by the fascia lata ; 11, gluteus maximus ; 12, gracilis ; 13, small part of
the adductor magnus ; 14, semitendinosus ; 15, biceps ; 16, fascia lata covering the
vastus externus.
MUSCLES OF THE UPPER LIMB.
199
Fig. 169.
200 MUSCLES OF THE UPPER LIMB.
MUSCLES ATTACHING THE UPPER LIMB TO THE TRUNK POSTERIORLY.
The trapezius muscle (cucullaris) arises by a thin aponeurosis from tho
protuberance of the occipital bone, and the inner third of its superior
curved line, from the ligamentum nuchse, and from the spines of the last
cervical and all the dorsal vertebrae, as well as from the supraspinous
ligaments. From this extended line of oiigin the fibres converge to their
insertion : the superior fibres, descending and turning forwards in the neck,
are inserted into the external third of the clavicle at its posterior border ;
the succeeding fibres pass transversely to the inner border of the acromiou
process and upper border of the spine of the scapula, while the inferior
fibres ascending terminate in a flat tendon which glides over the triangular
area at the base of the spine of the scapula, and is inserted into the rough
mark at the root of the spine. The greater part of the origin becomes
immediately muscular, but opposite the seventh cervical spine, and for the
distance of several vertebrae above and below that point, a flat tendon
extends outwards, widest at the middle of the space, and narrowing towards
the upper and lower ends, so that the aponeuroses of the two muscles taken
together have an elliptical form. The fibres of origin from the occipital
bone have no tendinous lustre, and resemble rather a strong fascia. The
muscles of the two sides, regarded together, have the form of a four- sided
figure, or shawl, pointing downwards : hence the names which have been
given to it.
The trapezius is superficial in its whole extent : it covers the splenius, the greater
part of the complexus above the splenius, the levator anguli scapulae, the rhomboidei,
the supraspinatus, and small portions of the infraspinatus, latissimus dom, and
lumbar aponeurosis. The spinal accessory nerve, and the superficial cervical artery,
pass into it from its deep surface.
The trapezius is not unfrequently shorter than above described, and the number of
dorsal vertebras with which it is connected is sometimes diminished even to six or
The latissimus dorsi arises by tendinous fibres from the spiuous processes
of the six or seven lowest dorsal vertebrae, and from the posterior layer of
the lumbar apoueurosis, through the medium of which it is attached to
the lumbar and upper sacral spines and back part of the iliac crest ; it also
arises by fleshy fibres for an inch or more from the iliac crest in front of the
outer margin of the lumbar aponeurosis, and from the last three or four
ribs by fleshy slips which iuterdigitate with the attachments of the external
oblique muscle. The fibres at the upper part are the shortest, and pass
almost horizontally outwards over the lower angle of the scapula, from which
they frequently receive a fasciculus of fleshy fibres ; those lower down
become longer and incline from below upwards, gradually increasing in the
degree of their obliquity ; finally, those which are attached to the ribs
ascend almost vertically. By this convergence the fibres of the muscle
eoine to form a narrow band of some thickness, which, accompanying the
teres major towards the axilla, winds round the lower and outer border of
that muscle so as finally to be placed in front of it. At this place it
terminates in a flat tendon of about two inches in length, which generally
becomes adherent to that of the teres major, but is again detached from it
at the insertion. The tendon is inserted in the floor of the bicipital groove
of the humerus, a little higher than the insertion of the teres major. From
this twisting of the muscle upon itself, the anterior surface of the tendon
is continuous with the posterior surface of the rest of the muscle.
LATISSIMUS DORSI.
201
Fig. 170. SUPERFICIAL VIEW OP
THE MUSCLES OP THE TRUNK,
SHOULDER AND HIP (after Bour-
gery). i-
o, occipital protuberance; C,
transverse process of the atlas ; D,
first dorsal vertebra ; L, first lum-
bar vertebra ; S, upper piece of the
sacrum ; Co, first piece of the
coccyx ; a, acromion ; 6, base of
the scapula ; i, crest of the ilium ;
1, upper and back part of the sterno-
mastoid muscle, spreading from the
mastoid process to the superior
curved line of the occipital bone ;
2, splenius, levator anguli scapulae,
and other deep muscles ; 3, 3', upper
and lower ends of the trapezius
muscle; 3', triangular tendon at-
tached to the base of the spine of
the scapula ; +., half of the oval
tendon belonging to the two trape-
zius muscles in the lower cer-
vical and upper dorsal region ;
4, 4, latissimus dorsi ; 4', 4",
line along which the latissimus
dorsi takes origin from the lumbar
fascia ; 5, infraspiuatus ; 6, teres
minor ; 7, teres major ; 8, middle
or acromial part of the deltoid ;
9, hinder part of the external
oblique muscle of the abdomen ; 10,
glutens medius, covered by the
aponeurosis of the fascia lata; 11,
11, line of origin of the gluteus
maximus from the posterior part of
the ilium to the coccyx ; 11' its inser-
tion into the fascia lata over the
trochanter major ; 11 ", a part of its
insertion into the femur ; 12,
biceps ; 13, semitendinosus ; 14,
adductor magrius ; 15, gracilis.
The latissimus dorsi is super-
ficial, except at its origin from the
dorsal vertebrae, where it is covered
by the trapezius, and at its inser-
tion, where it dips into the axilla.
It rests on part of the rhomboideus
major and infraspinatus, on the
teres major, serratus posticus in-
ferior, vertebral aponeurosis, ex-
ternal intercostal muscles, and the
posterior borders of the external
and internal oblique muscles.
Between the adjacent borders of
the latissimus dorsi, trapezius, and
rhomboideus major, there is left,
when, the scapula is drawn for-
ward, a triangular area, in which
a portion of one or two ribs and
an intercostal space becomes super-
ficial ; this is taken advantage of
for the purpose of auscultation.
Fig. 170.
202
MUSCLES OF THE UPPER LIMB.
The number of dorsal vertebra to which the latissimus dorsi is attached varies from
four to seven or eight, and the number of the costal attachments is also inconstant. A
muscular band is sometimes seen
to stretch from this muscle across
Fig. 171. the axilla to its anterior part,
where it terminates variously, in
the tendon of the greater pectoral,
in the coraco-brachialis muscle, or
in the fascia.
Fig. 171. DEEPER VIEW OF THE
MUSCLES OF THE TRUNK,
SHOULDER AND HIP (after Bour-
The trapezius, latissimus dorsi,
deltoid, gluteus maximus and ex-
ternal oblique muscles have been
removed. The bones are lettered
as in the preceding figure.
1, splenius capitis and splenius
colli ; ]', its lower end; 2, upper
part of the com plexus near its in-
sertion ; 3, levator anguli scapulse ;
4, rhomboideus minor ; above it + ,
a part of the serratus posticus supe-
rior ; 5, rhomboideus major ; 6,
part of the longissimus dorsi ; 6',
part of the tendons of insertion of the
sacro-lumbalis ; 7, part of the spi-
nalis dorsi ; 8, upper, and 8', lower
part of the serratus posticus infe-
rior ; 9, obliquus abdominis inter-
nus ; 10, supraspinatus ; 11, infra-
spinatus ; 12, placed upon the long
head of the triceps, points to the
teres minor; 13, teres major; 14,
serratus magnus ; 15, gluteus
medius ; 16, pyriformis; 17, portion
of the obturator internus; +and+,
superior and inferior gemelli ; 17',
the pelvic portion of obturator in-
ternus ; 1 8, the tendon of the obtu-
rator externus passing to its inser-
tion; 19, quadratus femoris ; 20,
upper part of the adductor magnus.
The rhomboidei muscles are
placed parallel to one another,
and are separated only by a
slight interval. They are ex-
tended obliquely from the
Bpinous processes of the lowest
cervical and some of the upper
dorsal vertebrae to the base of
the scapula.
The rhomboideus minor, a
comparatively narrow muscle,
arises from the spinous pro-
cesses of the seventh cervical
and first dorsal vertebrae and from the ligamentum nuchae. It inclines
PECTORALIS MAJOR. 203
downwards and outwards, and is inserted into the base of the scapula
opposite the triangular surface at the commencement of the spine.
The rhomboideus major, three or four times broader than the pre-
ceding muscle, arises from the spinous processes of the four or five
upper dorsal vertebrae, and their interspinous ligaments, and is inserted
into that part of the base of the scapula which is included between
the spine and inferior angle. Some of the fibres, instead of being fixed
to the bone, end in a tendon which is connected to the scapula above
the lower angle ; and, in consequence of this arrangement, the muscle
may, in part, be separated from the bone without division of its muscular
or tendinous fibres.
The greater part of the rhomboidei muscles is covered by the trapezius, a small
angular portion of the rhomboideus major only lying superficially in the interval
between the trapezius and latissimus dorsi ; the extent of this portion varies with the
position of the scapula, being increased when the arm and shoulder are raised from
the side. The rhomboidei cover the greater part of the serratus posticua superior,
and the posterior scapular artery descends on their deep surface.
The levator anguli scapulas, arises by slightly tendinous slips from the
posterior tubercles of the transverse processes of the first four or five
cervical vertebrae, between the splenius and scaleni muscles, and forms an
elongated fleshy mass which is inserted into the portion of the base of the
scapula intervening between the spine and superior angle.
The number of vertebral attachments of the levator anguli scapulae is subject to
some variation. A slip has been observed to extend to it from the mastoid process of
the temporal bone (Theile), and from the second rib (Meckel). It often appears as a
divided muscle, the parts connected with the several vertebrae remaining separate,
even to the place of insertion. In quadrupeds it is united with the serratus magnus,
so as to form a single muscle.
MUSCLES ATTACHING THE UPPER LIMB TO THE TRUNK ANTERIORLY.
The pectoralis major muscle arises from the sternal half, or a little more,
of the clavicle ; from the anterior surface of the sternum, extending as far
down as the insertion of the cartilage of the sixth rib ; from the cartilages
of the first six ribs, and also the bony part of the sixth rib ;. and from the
aponeurosis of the external oblique muscle of the abdomen. Springing
from this extensive origin its fibres form a thick mass, and, converging to
some extent, are inserted by a tendon of considerable breadth into the ridge
which forms the outer margin of the bicipital groove of the humerus, and
thence downwards as far as the deltoid impression. The muscular fasciculi
converge towards the axilla, and the muscle with its tendon is folded at
the axillary border, so that the clavicular part remains in front, while the
pectoral part passes behind. The arrangement is such that at last the
folded tendon of the muscle is inserted into the humerus in two nearly
parallel lines which are connected below. The fibres of the clavicular part,
in the order of their origin from without inwards, are prolonged into the
anterior or outer line of insertion in order from above downwards. The
pectoral part of the muscle is inserted into the inner or posterior line ;
the fibres which have the highest origin being the lowest at their
insertion, and those which arise lower in succession from the chest
passing higher and higher to their insertion on the humerus. Further,
204
MUSCLES OF THE UPPER LIMB.
Fig. 172.
'Fig. 172. SUPERFICIAL VIEW OF THE MUSCLES OF THE T-RUKK, FROM BEFORE.
1, sterno-mastoid of the left side ; 1', 1", platysma myoides of the right side ; 2, sterno-
PECTORALIS MAJOR.
205
hyoid ; 3, upper, 3', lower belly of the orao-hyoid ; 4, levator anguli scapulae ; 4', 4", scalene
muscles ; 5, anterior part of the trapezius ; 6, deltoid ; 7, upper part of the triceps brachii
in the left arm; 8, teres minor; 9, teres major; 10, latissi>nus dorsi ; 11, pectoralis
major ; 11', on the right side its clavicular portion ; 12, part of the pectoralis minor ; 13,
serratus raagnus ; 14, external oblique muscle of the abdomen ; 15, placed on the
xiphoid cartilage at the upper end of the linea alba ; 15 7 ", is placed on the umbilicus; 16,
is placed over the symphysis pubis, and at the lower end of the linea alba, above 16, the
pyramidal muscles are seen shining through the abdominal aponeurosis ; 15 to 17, the
linea seinilunaris at the outside of the rectus muscle, the transverse tendinous lines of
which are seen through the abdominal aponeurosis ; 18, part of the gluteus medius ; 19,
tensor vaginje femoris ; 20, rectus femoris; 21, sartorius ; 22, femoral part of the iliacus
and psoas ; 23, pectineus ; 24, adductor longus; 25, gracilis. On each side of 16, the
external abdominal ring is indicated.
it is to be observed that the tendon of insertion of the pectoral part
of the muscle passes higher than that of the clavicular part, extending as
far as the base of the great tuberosity, where it sends a thin prolongation
across the bicipital groove, and an offset to the head of the huinerus. The
lowest inserted portion of the muscle is closely united with the insertion of
the deltoid. From its inferior margin an offset is prolonged to the fascia of
the arm.
The folded inferior border of the pectoralis major forms the anterior margin of the
axilla ; the superior runs parallel with that of the deltoid muscle, from which it is sepa-
rated only by a slight interval which becomes wider towards the clavicle, and in which
Fig 173. VIEW OP SOME OP
THE DEEPER MtJSOLES OP
THE SHOULDER AND TRUNK,
FROM BEFORE.
Fig. 173.
On the right side the pec-
toralis major and external
oblique muscles have been re-
moved, a, coracoid process of
scapula ; b, manubrium of
sternum ; e, c, cartilage of
the fifth ribs ; d, ensiform
portion of the sternum ; 1,
upper part of the levator anguli
scapulae muscle ; 2, on the
middle of the clavide, points
to the subclavius muscle; 3,
pectoralis minor ; 4, subscapu.-
laris; 4 r , its insertion into the
lesser tuberosity of the tume-
rus ; 5, coraco-brachialis cut
fhort; 6, coracoid, and6',glenoid
head of the biceps brachii, both
cut short near the place where
they unite into one muscle ; 7,
on the tendon of the lat'ssimus
dorsi, points by a line to the ten-
don of the teres major, ooth cut
short and passing to their inser-
tion inside the bicipital groove ;
8, folded tendon of the pectoralis
major, cut short ; 9, inserted por-
tion of the deltoid ; 10, upper
part of the bracbiatis anticus at
its origin, embracing the insertion of the deltoid ; 11, part of the inner head of the triceps,
the middle head of which is seen passing behind the tendons of the latissimus and teres ;
12, on the fifth and eighth ribs, points to the insertion of the serratus magnus ; 13, 13',
recti abdominis.
206
MUSCLES OF THE UPPER LIMB.
run the cephalic vein and the humeral branch of the acromio-thoracic artery. The
anterior surface is subcutaneous in the greater part of its extent, being covered only
by some of the fibres of the platysma myoides and by the mamma. The posterior
surface rests chiefly on the pectoralis minor, and externally and internally to that
muscle forms the anterior wall of the axilla.
The tendinous fibres of origin of opposite sides sometimes decussate in front of the
sternum, and occasionally the fleshy fibres also of opposite sides come into contact.
In some instances additional muscular slips take origin from the aponeurosis of the
external oblique muscle, and in others the lower part of the muscle presents consider-
able deficiency.
The pectoralis minor arises from the upper margins and external surfaces
of three ribs near their cartilages usually the third, fourth and fifth and
from the neighbouring parts of the intercostal aponeurosis. Its fibres
converge to a narrow tendon, which is inserted into the anterior half of the
inner border and upper surface of the coracoid process, in contact with the
conjoined origin of the coraco-brachialis and biceps muscles.
This muscle is covered by the pectoralis major, and forms a part of the anterior
wall of the axilla. When the arm is much raised a portion of the muscle is seen
below the outer margin of the pectoralis major.
The subclavius muscle arises by a short thick tendon from the first costal
arch at the junction of the rib and cartilage, close to the costo-clavicular
ligament. From this tendon its fibres pass outwards and upwards, forming
Fig. 174.
Fig. 174. LATERAL VIEW
OP THE TRUNK, snow-
INO IN A DEEP DIS-
SECTION A VIEW OF
THE SERRATUS MAGNUS
MUSCLE.
a, coracoid process of
the scapula ; 6, glenoid
cavity; c, lower angle;
d, first dorsal vertebra ; 1,
VI, XII, the first, sixth,
and twelfth ribs ; 1, upper
portion of the serratus
magnus attached to the
first and second ribs ; 2,
second or middle portion
attached chiefly to the
third rib ; 3, lower or fan-
shaped portion attached to
the ribs from the fourth
to the ninth ; 4, external
intercostal muscles marked
in the third and ninth
spaces ; 5, upper costal
origins of the transver-
salis abdominis ; x , sca-
pular extremities of the
levator scapulae and omo-
hyoid muscles.
a rounded belly, which is inserted into the groove along the inferior surface
of the clavicle, extending as far as the recess between the conoid and
SERRATUS MAGNUS. ACTIONS. 207
trapezoid parts of the coraco-clavicular ligament. It is covered in front by
the costo-coracoid membrane or fascia.
' The serratus magnus muscle, placed upon the upper and lateral part of
the thorax, between the ribs and the scapula, is attached anteriorly by nine
fleshy angular slips to the first eight or sometimes nine ribs, two of these
being connected with the second rib ; it also derives some fibres from the
aponeurosis covering the upper intercostal spaces. Posteriorly, the muscle,
considerably narrowed, is attached to the line in fro at of the base of the
scapula, and at the upper and lower angles of the bone into the flat surfaces
which are excluded from the fossa of the subscapular muscle. The fibres
are arranged in three sets, thus a. Those from the first and second digita-
tions form a thick bundle which terminates on the flat area in front of the
upper angle of the scapula ; 6. those of the third and fourth digitations, but
especially the first of these, which is the inferior digitation of the second rib,
spread out into a triangular layer, the thinnest part of the muscle, and are
attached along the line in front of the base of the scapula, extending from
the place of insertion of the preceding part nearly to the lower angle of the
bone ; c. the remaining five or six digitations converge in the form of a fan,
and terminate in a thick mass, which is attached posteriorly to the flat sur-
face in front of the lower angle of the scapula.
By its deep surface, the serratus magnus rests on the upper ribs, the intercostal
muscles, and part of the serratus posticus superior. Its outer surface'is in contact
posteriorly with the subscapular muscle, and forms anteriorly the internal wall of the
axilla, being subcutaneous in the lower part of its extent.
Not unfrequently the number of digitations, and the number of the ribs with
which the muscle is connected, are greater than above described. Occasionally the
attachment to the first rib is wanting ; and examples are recorded of the absence of
the middle part of the muscle.
ACTIONS. Considered with reference to the movements of the limb upon the trunk,
the upper part of the trapezius, the levator scapulae, and the rhomboid muscles are
elevators of the shoulder ; the lower part of the trapezius, the pectoralis minor and
the subclavius are depressors ; the serratus magnus as a whole carries forward the
base of the scapula, and the rhomboidei draw it back ; the latissimus dorsi and
pectoralis major depress the humerus and carry it towards the middle line, behind or
in front, according as the one or other muscle is in action.
More particularly, the superior fibres of the trapezius elevates the clavicle ; the
succeeding fibres acting on the acromion have also some elevating action, but tend
rather to carry back the scapula towards the spine ; the inferior part of the muscle
acting upon the spine of the scapula would of itself depress that bone while it carried
it inwards towards the dorsal spines, but acting in concert with the upper two-thirds
of the muscle, a rotation is produced in the scapula round a central point in such a
manner that while the whole bone, and more especially the acromion, is raised and
carried towards the dorsal spines, the upper angle of the scapula is somewhat
depressed and carried inwards, while the lower angle is carried outwards and elevated.
The levator anguli scapulce, in elevating the superior angle of the scapula, counter-
acts in some degree the rotating action of the trapezius ; and this is further effected by
the rhomboid muscles, more especially the greater, which, as its main attachment is
near the inferior angle of the scapula, necessarily tends to raise that part and bring it
nearer to the dorsal spines. In this manner, when the trapezius, levator, and rhomboid
muscles act together, the scapula is raised without rotation, and its base is carried at
the same time inwards towards the dorsal spines.
The sukclavuis, by depressing the clavicle, diminishes the space between that bone
and the first rib, and may probably act principally as a support to the sterno-clavicular
articulation.
The pectoralis minor, in bringing the coracoid process downwards and forwards,
tends to throw the lower angle of the scapula backwards.
208 MUSCLES OF THE UPPER LIMB.
The serratns magnus muscle, by withdrawing the scapula from the spinal column,
enables the arm when raised from the shoulder to be still farther outstretched, as in
the movement termed extension in fencing. It comes powerfully into action in all
movements of pushing; it likewise combines with the trapezius in rotating the
scapula.
The latissimm dorsi carries the elevated arm downwards and backwards, rotating
it at the same time inwards, so as to make the palm look backwards, thus accomplish-
ing such a movement as is made by the arm in swimming. By passing over the
angle of the scapula it binds that process to the trunk, preventing its projection
backwards ; and by being folded round the outer border of the scapula, it limits the
projection outwards of the same angle when the arm is raised.
The pectoralis major muscle, while it combines with the latissimus dorsi in
depressing the humerus from the raised position, opposes that muscle by drawing the
limb forwards. It is placed upon the stretch when the arms are thrown backwards,
and is most shortened when they are folded across the chest.
Considered as acting on the trunk from the upper limb in a fixed condition, these
muscles have chiefly the following effect. They all tend to draw the trunk of the
body towards the limb, as in climbing, or other like efforts. The latissimus dorsi, if
acting on both sides, carries the body upwards and forwards, as in the use of crutches,
or in throwing a somersault from the hands backwards. The pectoral and latissimus
dorsi muscles are also muscles of forced inspiration, tending to raise and dilate the
ribs, more especially when the arms are elevated. The upper parts of both trapezii
muscles acting on the occipital bone aid the sterno-mastoid muscle in throwing for-
ward the chin ; and if one muscle only acts, it aids in rotating the head.
MUSCLES OF THE SHOULDER.
The deltoid is a coarsely fasciculated muscle, extending from the most
prominent part of the shoulder down a third of the upper arm. It arises
by a broad margin in three portions, an anterior from the external third of
the clavicle, a middle from the outer edge of the acromion, and a posterior
from the lower border of the spine of the scapula as far back as the tri-
angular surface at the inner end of that portion of the bone, and the fasciculi
from the extended origin, converging as they descend, are inserted by a
comparatively narrow but thick extremity into the triangular rough surface
above the middle of the humerus, on its outer side. This rough surface
receives the name of the deltoid impression.
At its posterior part the origin of the deltoid is thin and tendinous, and in the rest
of its extent fibrous septa dip down between the coarse muscular fasciculi. At the
insertion it is tendinous on the deep surface, and fibrous septa also project upwards
from thence into the substance of the muscle. The muscular fibres are arranged
pennately round those septa with such regularity as to have suggested to Albinus the
subdivision of the muscles into seven parts, four of- them broad above and narrow
below, and three intercalated between those parts, which are broad below and narrow
above. (Albinus, Histor. Muscul. Horn., p. 423.)
At the posterior border of the deltoid, the aponeurosis covering the infraspinatus
muscle divides into two thin layers, of which one covers the muscle superficially,
and the other lines its deep surface. At its anterior border this muscle is in
contact with the pectoralis major, the cephalic vein lying between them. In
immediate contact with the deep surface is the large bursa, which separates this
muscle and the acromion from the shoulder joint and the muscles supporting it.
The deltoid muscle covers the origins of the biceps, coraco-brachialis, and long head of
the triceps, and the insertions of the subscapularis, supraspinatus, infraspinatus and
teres minor muscles, as also the circumflex vessels and nerve.
The subscapularis muscle arises from all the venter of the scapula, with
the exception of the neck of the bone and the spaces occupied by the serratus
SCAPULAR MUSCLES.
209
magnus ; it is inserted ten-
din ously into the small tuber-
osity of the humerus, and by
fleshy fibres into the bone for
a short distance lower down.
Tendinous septa, attached to
the ridges of the subscapular
fossa, pass outwards in the
origin of the muscle, and
others are prolonged inwards
from the tendon of insertion.
Fig. 175. SUPERFICIAL MUSCLES
OP THE SHOULDER AND UPPER
LlMB, SEEN FROM BEHIND. %
a, acromion ; b, base of the sca-
pula ; c, tendon of the trapezius
muscle over the triangular surface
of the spine of the scapula ; d,
olecranon of the ulna ; e, external
condyloid eminence ; /, lower end
of the ulna ; 1, trapezius ; 2, acro-
mial part of deltoid ; 2', the part of
the same muscle rising from the
spine of the scapula ; 3, rhom-
boideus major ; 4, infraspinatus ;
5, teres minor ; 6, teres major ; 7,
latissimus dorsi ; +, triangular
space between the trapezius, rhom-
boid and latissimus ; 8, triceps ex-
tensor cubiti ; 8', its outer head ;
8", part of its inner head ; 9, an-
coneus ; 10, part of the brachialis
anticus ; 11, supinator longus ; 12,
extensor carpi radialis longior. The
explanation of the remaining refer-
ences will be found in the descrip-
tion of fig. 182.
The tendon of this muscle is in-
corporated with the capsule of the
shoulder-joint, and between its
upper margin and the coracoid
process is a bursa usually commu-
nicating with that joint. Ante-
riorly it is in contact at ^its origin
with the serratus magnus, and is
covered at its insertion by the
coraco-brachialis and biceps, while,
in the interval between, it forms
part of the posterior wall of the
axilla.
The supraspinatus muscle
arises from the whole surface
of the supraspinous fossa of
the scapula as far forward as
the outer extremity of the
spine, and from an aponeurosis,
by which it is covered. It
Fig. 175.
210
MUSCLES OF THE UPPEK LIMB.
Fig. 176.
completely fills the
and its fibres converge be-
neath the acromion to a
tendon, which adheres to the
capsule of the shoulder- joint,
and is inserted into the
upper of the three facets on
the great tuberosity of the
humerus.
Fig. 176. SUPERFICIAL MUS-
CLES OF THE SHOULDER AND
UPPER LIMB, FROM BEFORE. %
1, pectoralis major; 1', its
clavicular portion ; 2, deltoid ;
3, biceps brachii ; 3', its tendon
of insertion ; 3", its aponeu-
rotic slip ; 4, brachialis anticus ;
4', its inner and lower portion ;
5, inner head of the triceps ; 5',
lower part of the same, seen
rising from behind the inter-
muscular septum. The expla-
nation of the remaining references
will be found in the description of
fig. 179.
The infraspinatus muscle,
occupying the greater part
of the infraspinal fossa,
arises from the under surface
of the spine and from the
whole surface of the blade
of the scapula below the
spine, except those parts at
the lower angle and along
the external border, to which
the teres muscles are at-
tached. The fibres converge
to a tendon, which is con-
cealed at first within the sub-
stance of the muscle, and is
inserted into the middle
facet of the great tuberosity
of the humerus.
The supraspinatus muscle is
covered by the trapezius and the
acromion process.
The infraspinatus muscle is
bound down by an aponeurosis,
which superiorly and externally
divides so as to enclose the
deltoid muscle. It is covered
by the deltoid at its upper and
outer part, and by the trapezius
at its upper and inner part, by
SCAPULAR MUSCLES.
211
the latissimus dorsi at its lower angle, and in the intermediate portion it remains
superficial.
The teres minor muscle is placed along the outer border of the infraspinatus,
and is intimately connected with that muscle. It arises by a series of fibres
from a narrow obliquely grooved surface on the dorsum of the scapula close
to the axillary border, aud from aponeurotic septa between it and the infra-
spiuatus and teres major muscles, and is inserted by tendon into the greater
tuberosity of the humerus, immediately below the infraspinatus, and by fleshy
fibres into the bone for a short distance lower down.
Fig. 177.
Fig. 177. MUSCLES OF THE RIGHT
SHOULDER AND ARM, SEEN FROM
BEHIND.
The acromion process and a part
of the spine of the scapula, with
the deltoid muscle, have been re-
moved, a, coracoid process ; 6,
triangular surface at the commence-
ment of the spine ; c, is close to
the cut portion of the spine ; d,
greater tuberosity ; e, olecranon of
the ulna ; /, is close to the external
condyloid eminence and head of the
radius ; 1, supraspinatus muscle ;
2, infraspinatus ; 3, teres minor,
placed over the triangular interval ;
4, teres major ; 5, part of latissi-
mus dorsi ; + , slip from the in-
ferior angle of the scapula ; t, on
the edge of the humerus, points to
the tendon of the latissimus dorsi
and the quadrangular interval ; 6,
scapular head of the triceps, passing
above between the teres major and
miiior ; 6', outer head ; 6", lower
part of the same, below the spiral
groove, continued from the inner
head ; 6'", part of the inner head ;
7, anconeus.
The teres major muscle
arises from the flat oval sur-
face on the dorsum of the
scapula near its inferior angle,
slightly from the axillary bor-
der of the bone, and from the
septa interposed between it
and the teres minor and infra-
spinatus. It is inserted by a
flat tendon about two inches
wide, into the inner or posterior
border of the bicipital groove
of the humerus, behind and in
contact with the tendon of the
latissimus dorsi, to which it is adherent for a short space. Close to the
insertion, however, the tendons of these muscles are separated by a small
bursa. The fibres of the muscle are longitudinal.
p2
212 MUSCLES OF THE UPPER LIMB.
Posteriorly this muscle is covered at its lower part by the latissimus dorsi, and at
its upper part it is crossed by the long head of the triceps. The outer side is sur-
rounded by the latissimus dorsi ; and the anterior surface is concealed in the upper
part of its extent by the tendon of that muscle. The inner border of the muscle
forms the other margin of a triangular space, of which the other sides are the upper
part of the humerus, and the axillary border of the scapula covered before and
behind by the subscapular and teres minor muscles; this triangle is divided by
the long head of the triceps into a superior or external quadrilateral, and an inferior
or internal triangular compartment. Through the quadrilateral space pass back-
wards the posterior circumflex vessels and the circumflex nerve ; and in the trian-
gular subdivision the dorsal branch of the subscapular artery passes round the margin
of the scapula into the infraspinous fossa. The scapular slip of the latissimus dorsi
arises in connection with the teres major.
ACTIONS. The deltoid muscle raises the arm from the side as far as the structure
of the shoulder-joint permits : that is, till it is at right angles with the trunk.
Further elevation of the upper limb is effected chiefly by the trapezius ; and it
may be remarked, that the insertion of that muscle corresponds exactly in extent
to the origin of the deltoid, so that the two muscles may be considered continuous
in structure and in action. The anterior fibres of the deltoid combine with the pecto-
ralis major to draw the humerus forwards ; the posterior assist in drawing it back-
wards. The supraspinatus, infraspinatus, and subscapularis muscles being placed
more closely round the joint, when acting in concert with the deltoid probably
give steadiness and precision, while the deltoid gives the main elevating force to
the movement. The supraspinatus simply elevates : the infraspinatus and sub-
scapularis carry the arm backwards or forwards when it is raised, and rotate it
outwards or inwards when hanging by the side. The teres major rotates the
raised humerus inwards, the teres minor outwards : acting together, they assist in
depressing the arm.
MUSCLES OF THE ARM.
The coraco-brachialis muscle, elongated in form, arises from the tip of the
coracoid process of the scapula, between the pectoralis minor and the short
head of the biceps, with which latter it is for a short distance conjoined.
It is inserted into the inner border of the humerus near its middle, in a
linear impression of from two to three inches in length, between the origin
of the triceps and the brachialis anticus. From its insertion a tendinous
offset is prolonged upwards to the head of the humerus.
This muscle is usually pierced by the musculo-cutaneous nerve ; its outer border is
in contact with the biceps muscle, and its inner with the brachial artery, by which it
is crossed obliquely near its insertion. It lies in front of the tendons of the subscapu-
laris, latissimus dorsi and teres major, and is covered by the deltoid and pectoralis
major muscles.
The Uceps flexor cubiti muscle has two heads of origin of unequal length :
one of these, the internal or short head, arises conjointly with the coraco-
brachialis from the coracoid process of the scapula by a tendon which is
soon continued into muscle; the other, the long head, arises by a cylindrical
tendon from the upper border of the glenoid ligament, within the capsule
of the shoulder- joint, and this tendon, passing over the head of the humerus,
leaves the joint by the bicipital groove, and gradually enlarges into the fleshy
head as it descends. The muscular fibres from those two heads, lying side
by side, unite to form an elongated and thick belly, occupying the middle
and lower part of the arm : the muscle then suddenly becoming narrower
a little above the bend of the elbow, is continued into the flat rounded
MUSCLES OF THE AHM.
213
tendon of* insertion. This tendon, slightly twisted upon itself as it descends,
is inserted into the rough posterior margin of the tuberosity of the radius,
and glides on the anterior smooth surface of that process by the inter-
vention of a synovial bursa. From the front of the lower part of the muscle,
arid from the tendon at its inner side, there proceeds a fibrous expansion of
an aponeurotic nature, which passing downwards and inwards becomes
blended with the fascia of the forearm over the pronator radii teres.
Fig. 178. DEEP VIEW OF THE
MUSCLES OF THE RIGHT SHOULDER
AND ARM, FROM BEFORE.
Fig. 178.
The clavicle is divided near its
middle ; the pectoralis minor is
entirely removed, and portions of
the biceps, pectoralis major, del-
toid, and latissimus dorsi, are left
near their attachments, a, acro-
mion ; 6, cut part of the clavicle ;
c, coracoid process ; d, upper, and
e, lower triangular space left at
the upper and lower angles of the
scapula on its anterior surface when
the serratus magnus is removed ;
/, great tuberosity of the humerus ;
<7, surface of the humerus below
the bicipital groove, near the ridge
of attachment of the pectoralis
major and deltoid muscles ; h,
outer, and i, inner condyloid emi-
nence of the humerus ; 1, cut
coracoid head, and 1', cut glenoid
tendon, of the biceps muscle ; 2,
folded tendon of insertion of the
pectoralis major, of which one por-
tion is seen running up to the bici-
pital groove ; 3, lower cut end of
the deltoid ; 4, coraco-brachialis
muscle ; 5, subscapularis ; 5', its
insertion into the lesser tuberosity ;
6, teres major ; 6', its insertion
behind and below the latissimus
dorsi ; 7, part of the latissimus
dorsi ; + , slip proceeding from the
inferior angle of the scapula ; 7',
insertion of the tendon, after wind-
ing round the teres major, in front
of and higher than that muscle ;
8, 8', brachialis anticus ; 9, long or
scapular head of the triceps, at the
upper part seen between the teres
major and subscapularis muscles,
the teres minor not represented ; 9',
inner humeral head of the triceps ;
10, flexor communis digitorum pro-
fundus, taking origin round the in-
sertion of brachialis anticus ; 11, tendon of insertion of the biceps.
Concealed above by the deltoid and pectoralis major muscles, the bleeps forms in
the rest of its extent the prominence of the front of the arm. It rests in its upper
half on the humerus, and in its lower on the brachialis anticus, and by its inner
margin is in contact in its upper half with the coraco-brachialis, in its lower with the
214 MUSCLES OF THE UPPER LIMB.
brachial artery. Its inferior tendon is in contact with the supinator brevis, and the
fibrous expansion is stretched across the brachial artery and median nerve.
Occasionally a third head, arising from the humerus in more or less close connection
with the brachialis anticus and the insertion of the coraco-brachiali*, is added to the
biceps muscle : this head lies generally on the outer side of the brachial artery, and
has sometimes been found covering it. A muscular band has also been observed
extending downwards from the biceps to the intermuscular septum over the inner
condyle of the humerus, and passing over the brachial artery. (R. Quain, "The
Anatomy of the Arteries," &c., p. 270, pi. 57.)
The brachialis anticus muscle (brachiaeus interims) arises from the lower
half of the anterior surface of the humerus. At the upper part of its
origin it embraces the insertion of the deltoid by two angular fleshy pro-
cesses; it extends downwards to the capsule of the elbow-joint, and
inwards to the internal supracondyloid ridge and intermuscular septum
in its whole extent; on its outer side it is separated from the external
ridge and septum in the greater part of its length by the supinator longus,
and only arises from it for a short distance at its upper end. It is closely
adherent to the ligament in front of the elbow-joint, and terminates below
in a thick mass which is inserted into the rough triangular surface on
the front of the coronoid process of the ulna.
This muscle projects at each side of the biceps, and supports the brachial artery
and median nerve. Fibres have been found to pass inwards from it, over the brachial
artery, to the internal intermuscular septum.
The triceps extensor cubiti, occupying the whole space behind the humerus
and intermuscular septa, consists superiorly of three portions or heads which
are united lower down in a common mass, the tendon of which is inserted
into the posterior and upper part of the olecranon, a bursa intervening
between that tendon and the most prominent part of this process. The
middle or long head (musculus anconeus longus) arises from the lower
part of the glenoid cavity and an adjoining rough portion of the inferior
border of the scapula, by a tendon which spreads over the sides of the
muscular structure proceeding from it. The muscular fibres from this
source descend and form the middle and superficial part of the common
mass, presenting a flat vertical tendon on their surface inferiorly. The
external head (m. anconeus brevis) takes origin by tendinous and fleshy
fibres from the humerus along a line extending from the insertion of the
teres minor, downwards on the outer border of the humerus as low as
the musculo-spiral groove; from this line of origin its fibres, which are
comparatively short, descend obliquely to be inserted into the tendon of
the middle part. The lowest fibres of this head are bound down by a slight
aponeurotic arch over the extremity of the musculo-spiral groove, and below
their inferior margin other fibres are found arising from the external inter-
muscular septum and the surface of the humerus behind ; but these last
pass to be inserted more deeply than into the tendon of the middle part of
the muscle, and are rather to be considered as belonging to the muscular
mass which forms the internal head. The internal or deep head (m. an-
coneus internus), the shortest of the three, commences in a narrow pointed
part behind and below the tendon of insertion of the teres major, and
arises from the whole posterior surface of the bumerus below the musculo-
spiral groove, from the internal intermuscular septum in all its length,
and from the inferior portion of the external septum ; some of its lower
FLEXOR AND PROXATOR MUSCLES. 215
fibres are inserted immediately into the olecranon, and the greater part of
them join the deep surface of the common tendon. No muscular fibres
arise from the musculo-spiral groove itself.
The method of description above followed, in which all the fibres arising below the
musculo-spiral groove are assigned to the internal head, originated with Theile.
(Miiller's "Archiv," &c. 1839, p. 420, and "Soemmerring v. Baue," &c.) The long
head of the triceps lies between the two teres muscles above, and is in contact with the
capsule of the shoulder-joint. The musculo-spiral nerve, and the superior profunda
artery, pass between the inner and outer heads as they lie in the musculo-spiral
groove.
Subanconeu$.0n removing the triceps from the lower part of the humerus, some
muscular fibres will be found passing from that part of the bone to the capsule of the
elbow-joint. These fibres, which are analogous to the subcrureus in the lower limb,
have been described as distinct from the triceps under the name subanconeus.
The anwneus muscle (anconeus quartus) although placed below the elbow
and in that respect belonging to the forearm, is in its structure, function
and nervous supply, so intimately connected with the triceps, that it is most
appropriately associated in description with that muscle. It arises by a
narrow tendon from the extremity of the outer condyloid eminence of the
humerus, at the posterior aspect. From this the fibres diverge from one
another, the upper being horizontal, the rest passing downwards with in-
creasing degrees of obliquity, and are inserted into the olecranon on its
radial aspect, and into the adjacent impression on the upper third of the
shaft of the ulna. Its superior fibres are parallel to the lowest fibres of the
internal head of the triceps, and are generally in contact with them.
ACTIONS. The biceps muscle raises the arm at the shoulder and flexes the elbow-
joint ; the long head of the triceps depresses the arm at the shoulder, and extends the
elbow-joint. The short head of the biceps draws the arm inwards as well as upwards,
as does also the coraco-brachialis. If the biceps be called into action when the hand
is in pronation, its first effect, in virtue of its insertion into the back part of the
tuberosity of the radius, is to produce supination of the forearm. The brachialis
anticus is a simple flexor of the elbow; the external and internal heads of the triceps,
and the anconeus muscle, are simple extensors of that joint.
MUSCLES OF THE FOREARM.
a. Anterior and Inner Regions (Flexors and Pronator s).
The muscles on the front and inner part of the forearm are disposed
in two sets, one being superficial, the other more deeply seated.
The superficial layer of muscles comprehends the pronator radii teres,
flexor carpi radialis, palmaris longus, flexor carpi ulnaris and flexor digito-
rum sublimis. These five muscles are intimately united at their origin from
the inner condyle, to which they are attached by a common tendon which
gives fibres to each, and also sends septa between them.
The pronator radii teres, the most external of the group, arises by two
distinct heads; one, large and superficial, is derived from the upper part of
the inner condyloid eminence of the humerus, and from the common tendon
above mentioned ; also from the fascia and the intermuscular septum of the
forearm. The second head, a thin fasciculus deeply placed, conies from
the inner margin of the coronoid process, and joins the other at an
acute angle. The fleshy belly thus formed proceeds outwards and down-
216
MUSCLES OF THE UPPER LIMB.
wards, and ends in a flat tendon which turns over the radius, and is inserted
into a rough surface at the middle of the outer side of that bone.
Fig. 179.
Fig. 179. SUPERFICIAL MUSCLES OF THE FOREARM
AND HAND, SEEN PROM THE FRONT.
3, biceps flexor cubiti ; 3', its tendon of insertion ;
3", its aponeurotic slip ; 4, brachialis anticus ; 4',
its inner and lower portion ; 5', lower part of the
triceps, seen rising from behind the intermuscular
septum ; 6, pronator radii teres ; 7, flexor carpi
radialis ; 8, palmaris longus, passing at 8' into the
palmar aponeurosis ; 9, flexor carpi ulnaris ; 10,
supinator longus ; between 10 and 3, f marks a
part of the supinator brevis ; 11, extensor ossis
nietacarpi pollicis ; 12, extensor primi internodii ;
13, lower part of the flexor digitorum sublimis ; 14,
flexor longus pollicis ; 15, small part of the flexor digi-
torum profundus ; 16, palmaris brevis, lying on the
muscles of the little finger ; 17, abductor pollicis.
The pronator teres is placed superficially in the
greater part of its extent; but towards its inser-
tion it is crossed by the radial artery and nerve,
and the supinator longus muscle. The ulnar bor-
der is in contact with the flexor carpi radialis
and palmaris longus : the radial border forms the
inner boundary of the angular space at the bend of
the arm, in which are placed the brachial artery,
the median nerve, and the tendon of the biceps
muscle. The pronator teres covers the flexor sub-
limis digitorum ; the ulnar artery passes behind
the whole muscle, and the median nerve between
its two heads.
Additional fibres frequently arise from the inter-
muscular septum above the inner condyloid emi-
nence of the humerus, or from the supracondy-
loid process when that'is present. This peculiarity
is sometimes associated with a change in the
direction of the brachial artery.
The flexor carpi radialis arises from the
inner condyle by the common tendon, from
the fascia of the forearm, and from the inter-
muscular septa placed between it and the
pronator teres on one side, the palmaris longus
on the other, and the flexor sublimis pos-
teriorly. The fleshy fibres end in a flat
tendon, a little below the middle of the
forearm. Arrived at the carpus, the tendon
occupies a special fibrous compartment situated in the outer part of the
anterior annular ligament of the wrist, and runs through a groove in the
os trapezium, to which it is bound by a thin fibrous sheath lined by a
synovial membrane, and is inserted into the extremity of the second
metacarpal bone.
A fasciculus from the inserted tendon sometimes passes to the third and even to
the fourth metacarpal bone.
In the lower half of the forearm the radial artery is placed to the outer side of the
tendon.
SUPERFICIAL FLEXOR OF THE FINGERS. 217
The palmar is longus, the smallest muscle of this group, is placed between
the flexores carpi radialis and ulnaris, resting on the flexor sublimis: it
arises from the inner condyle and the intermuscular septa ; forming a small
muscular belly, which soon ends in a long slender tendon, inserted into
the palmar fascia near the middle of the wrist, and sometimes sending a
slip to the short muscles of the thumb.
The palmaris longus is frequently wanting. It is subject to many variations of
form ; e. g. the muscular fibres may occupy the middle of the muscle, which then
commences and ends by an elongated tendon; or the muscular structure may be
placed towards the lower end, the upper part being tendinous. Occasionally there
are two long palmar muscles, one having the ordinary shape, while the other has one
of the forms above referred to. The most remarkable peculiarity is that in which a
small muscle, a second palmaris longus, placed nearer to the inner border of the fore-
arm than the usual muscle, covers the ulnar artery for some space above the carpus,
and terminates partly in the annular ligament or in the fascia, and partly in the
short muscles of the little finger.
The flexor carpi ulnaris, the innermost muscle of the superficial group,
arises by two heads, one of which is attached tendinously to the inner
condyloid eminence of the humerus, the other to the inner side of the
olecrauon, and to the posterior border of the ulna for three-fourths of its
length, by an aponeurosis which is inseparably connected with the investing
aponeurosis of the limb. The fibres from the humeral head descend
vertically, those from the ulna pass obliquely forwards, and terminate in a
tendon, which, emerging from the first head, descends along the anterior
margin of the muscle, and is ultimately inserted into the pisiform bone :
this tendon is prolonged, by means of ligamentous structures, to the fifth
metacarpal and unciform bones, as well as to the annular ligament and
muscles of the little finger.
This muscle rests on the flexor profundus digitorum. The ulnar nerve passes down
into the forearm in the interval between the two heads, and is then covered by the
muscle : for the middle part of its course the ulnar artery is also covered by it, and
in the lower part of the forearm, the nerve and artery, emerging from behind the
muscle, lie on its radial side.
The flexor digitorum sublimis vel perforatus, the superficial flexor of the
fingers, is a broad flat muscle placed behind the preceding muscles, along
with which it takes its principal origin. It is divided inferiorly into four
tendons, which pass to be inserted into the second phalanx of each of the
four inner digits. More particularly, it arises from the inner condyle by
the common tendon, and the fibrous septa common to it and the other
muscles; from the internal lateral ligament; from the anterior surface of
the coronoid process at the inner side; and by a thin flat portion from
the oblique line and part of the anterior border of the radius. The
fleshy belly enlarges towards the middle of the forearm, and again
diminishes somewhat before its division. The four tendons pass under the
annular ligament of the wrist in pairs, one in front of the other; the
anterior pair consisting of those for the middle and ring fingers, the poste-
rior of those for the index and little fingers. That for the little finger is
smaller than the others.
In the palm of the hand the tendons diverge, and each, accompanied by
a tendon of the flexor profundus, enters a fibrous sheath which binds both
tendons down to the palmar surface of the phalanges. Opposite the first
phalanx the tendon of the flexor sublimis divides into two parts, which fold
218
MUSCLES OF THE UPPER LIMB.
closely round the tendon of the deep flexor, and are reunited by their
margins behind it : the two portions of the tendon thereafter separating,
pass to be inserted one on each side into a ridge at the middle of the lateral
border of the second phalanx. A large synovial bursa loosely invests the
tendons of both the superficial and deep flexors of the fingers behind the
annular ligament, extending downwards into the palm of the hand. In the
little finger it approaches the synovial lining of the sheath, and in the
thumb it usually communicates with it.
Fig. 180.
Fig. 180. METACARPAL AND PHALANGEAL BONES OF Two FINGERS, WITH THE TENDONS
AND THEIR ACCESSORY STRUCTURES. ^
In A, the tendons of the flexor muscles are bound to the finger by the fibrous bands
or retinaeula. In B, these bands have been removed, as well as the synovial capsules and
vincula accessoria : 1, raetacarpal bone ; 2, tendon of the flexor sublimis ; 3, tendon of
the flexor profundus ; *, perforation of the sublimis by the profundus tendon ; 4, tendon
of the extensor digitorum communis ; 5, one of the lumbricales muscles ; 6, one of the
interosseous muscles.
The sheaths of the flexor tendons, by which they are bound down to the
fingers, are formed opposite the first and second phalanges by strong ten-
dinous bands of transverse fibres (ligamenta vagiualia) attached to the
rough margins of the palmar surfaces of the phalanges. Opposite the joints,
flexion is secured by the substitution for those bands of a thin membrane,
strengthened by oblique decussating fibres. The tendinous sheath has a
synovial lining, which is simple in front, but posteriorly dips between the
tendons. A few slender and loose bands (viucula accessoria tendinum,
vincula vasculosa) extend from the floor of the sheath to the deep surface
of both tendons. Behind each tendon, near its insertion, is a short mem-
branous structure (ligamentum breve), which fixes the tendon to the front
of the phalanx situated above that into which it is inserted.
Superiorly, the flexor sublimis is concealed by the other muscles of the superficial
get, and is crossed near the radius by the radial artery ; it rests on the flexor pollicis
longus and flexor profundus, separated from the latter by the median nerve and the
ulnar artery. In the palm of the hand, its tendons are covered by the palmar fascia,
the superficial palmar arterial arch, and the branches of the median nerve ; and they
lie in front of the accompanying tendons of the flexor profundus.
A muscular slip is frequently given from this muscle to the flexor profundus, or to
the flexor longus pollicis. The tendon for the little finger is sometimes wanting.
The deep-seated muscles, on the anterior surface of the forearm, are the
flexor profundus, flexor pollicis longup, and pronator qnadratus.
DEEP FLEXOR OF THE FINGERS.
219
Fig. 181.
The flexor profimdus digitorum, or flexor perforans, a large and thick
muscle, arises from the hollow at the inner side of the olecranon ; from the
inner and anterior surfaces of the ulna for three-fourths of its length ;
from the ulnar half of the interosseous liga-
ment for the same distance ; and from the
aponeurosis attaching the flexor carpi ulnaris
to the ulna. It divides inferiorly into four
tendons, only one of which, that for the index
finger, is distinct from the others above the
wrist the rest being connected together as
far as the palm. In the palm the tendons,
as they diverge, give origin to the lumbricales
muscles. Opposite the first phalanx, the
tendon of each finger passes through the
opening formed for its transmission in the
tendon of the flexor sublimis, and is inserted
into the base of the last phalanx.
Fig. 181. DEEP ANTERIOR MUSCLES OF THE
FOREARM.
The humeral muscles and the superficial muscles
of the forearm and hand, together with the lumbri-
cales, have been removed, and the place of the
anterior annular ligament of the carpus is marked
by two dotted lines, a, surface of the huraerus
above the coronoid fossa ; b, rough surface of the
ulna, into which the brachialis anticus is inserted ;
c, head of the radius covered by the orbicular liga-
ment, and between this and a, the anterior ligament
of the elbow-joint; +, the internal lateral ligament;
d, the lower end of the radius ; e, that of the ulna;
/, the scaphoid and trapezium bones ; g, the pisiform
l>one ; 1, supinator radii brevis ; 2, flexor longus
pollicis ; 3, flexor digitorum profundus ; 3', its four
tendons, where they are about to pass into the band
under the annular ligament ; 4, pronator quadratus
on the lower part of the radius ; 5, deep head of
flexor brevis pollicis ; 6, adductor pollicis ; 7, first
dorsal interosseous muscle ; 8, in the second space,
is placed between the first palmar and the second
dorsal interosseous muscles ; in the third space,
between the third dorsal and the second palmar ;
in the fourth space, between the fourth dorsal and
the third palmar. (For the lumbricales muscles, see
Figs. 180 and 186.)
The upper extremity of this muscle embraces the
insertion of the brachialis anticus. On its surface
lie the median nerve and the ulnar artery and
nerve. The external border is parallel with the
flexor longus pollicis, from which it is separated, on the interosseous membrane, by
the anterior interosseous vessels and nerve. The tendons are covered by the synovial
sacs, which have been mentioned in connection with the flexor sublimis.
The lumbricales are four tapering fleshy fasciculi, passing from the
tendons of the flexor profundus to the first digital phalanges. They arise
by fleshy fibres from the outer or radial borders of the deep flexor tendons,
and proceed forwards to the radial sides of the fingers, where each ia
220 MUSCLES OF THE UPPER LIMB.
inserted into an expansion of the extensor tendon on the dorsal aspect
of the metacarpal phalanx of the finger. The two inner lumbricales
muscles take origin likewise from the ulnar margins of the second and third
tendons.
The number of these muscles is not imfrequently diminished to three, and in rare
instances is increased to five or six. The destination of one or two of them is often
changed, and one finger (most frequently the third or fourth) has sometimes two
inserted into it. Lastly, one muscle may be inserted into two fingers.
The flexor longus pollicis, placed side by side with the flexor profundus,
arises from the grooved surface, on the fore part of the radius from the
oblique line to the edge of the pronator quadratus ; it arises also from
the adjacent part of the interosseous ligament, and by a rounded fleshy
and tendinous slip distinct from the rest of the muscle, from the inner part
of the coronoid process. The muscle ends in a tendon which passes behind
the annular ligament of the wrist close to the trapezium, turns outwards
between the two heads of the flexor brevis and between the sesamoid bones,
and, entering a canal similar to those of the other flexor tendons, is finally
inserted into the base of the second phalanx of the thumb.
Inferiorly, a part of this muscle is placed superficially between the flexor carpi
radialis and the supinator longus, where it supports the radial vessels.
The pronator quadratus, placed close to the bones behind the last two
muscles, arises from the anterior and inner surfaces of the ulna for about
two inches above its carpal extremity ; its fibres cross the lower part of
the forearm, some transversely and others obliquely, and they are inserted
for an equal distance into the fore part of the radius.
6. Posterior and Outer Regions (Extensors and Supinators).
The muscles of this group are, like those of the front of the forearm,
divided into a superficial and a deep layer.
The superficial muscles are six in number, viz., the supinator longus, the
extensores carpi radiales longior and brevier, the extensor communis
digitorum, extensor minimi digiti, and extensor carpi ulnaris.
The supinator radii longus arises from the upper two-thirds of the
external condyloid ridge of the humerus, and is interposed between the
brachialis anticus and the external intermuscular septum, to which its fibres
are attached. The thin fleshy mass proceeding from this elongated origin
descends upon the anterior and outer border of the forearm, and ends
about the middle in a flat tendon, which is inserted into the external border
of the radius, near the base of the styloid process.
This muscle is covered only by skin and fascia, except at its insertion, where two
of the extensor tendons of the thumb lie superficial to it.
The extensor carpi radialis longior, partly covered by the supinator longus,
arises from the lower part of the external condyloid ridge of the humerus,
and from the intermuscular septum. Its muscular belly ends at the
meeting of the upper and middle thirds of the forearm in a flat tendon,
which passes conjointly with that of the following muscle over the lower
end of the radius in the outermost of the two broad grooves on the posterior
surface of that bone, and is inserted into the base of the second metacarpal
bone. A small bursa lies beneath the tendon at its insertion.
COMMON EXTENSOR OF THE FINGERS.
221
Fig. 182.
The extensor carpi radialis brevior arises from the outer condyloid
eminence of the humerus by a tendon common to it and the other extensor
muscles, from the intervening fibrous septa, from a superficial tendinous
expansion, and from the external lateral liga-
ment of the elbow- joint. Its muscular belly
ends in a flat tendon, which descends with
that of the extensor longior, passes through
the same groove of the radius with it, and
is inserted into the base of the metacarpal
bone of the middle finger. A bursa is placed
between this muscle and the supinator brevis,
an:l a smaller one between the tendon and the
metacarpal bone.
Fig. 182. SUPERFICIAL MUSCLES OF THE FOREARM
AND HAND, SEEN FROM BEHIND.
d, olecranon ; e, external condyloid eminence ;
/, lower end of the ulna ; 8, main tendon of the triceps
extensor cubiti ; 8", its inner head ; 9, anconeus ; 10,
part of brachialis anticus ; 11, supinator longus; 12,
extensor carpi radialis longior; 13, brevior;
14, extensor communis digitorum ; 15, extensor carpi
ulnaris ; 15', its insertion into the fifth metacarpal
bone; +, between 14 and 15, extensor minimi
digiti ; 16, origin of the flexor carpi ulnaris by an
aponeurosis from the back of the ulna; 17, extensor
ossis metacarpi pollicis ; 17', its insertion into the
first metacarpal bone ; 18, extensor primi internodii
pollicis; 18', its insertion into the first phalanx ; +
and +, posterior annular ligament of the carpus or
retinaculum of the extensor tendons ; at +, the ten-
dons of the long and short radial extensors ; at +,
the tendon of the extensor minimi digiti ; 19, tendon
of the extensor secundi internodii ; 20, is placed on the
proximal end of the second metacarpal bone, close to
the insertion of the radial extensors of the carpus :
in the hand, the dorsal interossei muscles are shown,
and on the middle finger the insertion of the ex-
tensor tendons.
This muscle is covered by the supinator longus
and extensor carpi radialis longior, and conceals the
supinator brevis and the insertion of the pronator
radii teres. The tendon of this muscle and that
of the extensor carpi radialis longior are crossed
obliquely by the extensors of the metacarpal bone
and first phalanx of the thumb.
The extensor communis diyitorum, placed
between the extensor carpi radialis brevior
and the extensor minimi digiti, arises by a
tendon common to it and the other super-
ficial extensor muscles, also from the fascia of the forearm, and the
septa between it and the adjoining muscles. Somewhat below the middle
of the forearm the muscular part ends in four tendons, which pass
between the posterior annular ligament of the wrist and the innermost
broad groove on the back of the radius, and diverge as they proceed along
the carpus and metacarpus to reach the fingers. Here each is increased by
tendinous fibres derived from the lumbricales and interosseoua muscles,
222
MUSCLES OF THE UPPER LIMB.
forming a fibrous expansion, which covers the back of the first and second
digital phalanges, and terminates upon the third phalanx. It is attached to
the second and third phalanges in the following manner. Opposite the first
bone the tendon divides into three fasciculi ; the central one is much thinner
than the others, and is inserted into the base of the second phalanx ; the
two lateral parts, continuing onwards, are joined together towards the
middle or fore part of the second phalanx,
and, having passed beyond this, are inserted
into the last phalanx. On the index and
little fingers the tendons are joined before
their division, by the special extensor tendons
of those digits.
Fig. 183. DEEP POSTERIOR MUSCLES OF THE
FOREARM.
a, posterior surface of the humerus above tlie
olecranon fossa; 6, upper and back part of the
olecranon ; c, outer and back part of the middle
of the radius ; d, lower part of the ulna, grooved for
the tendon of the extensor carpi ulnaris ; e, base of
the second metacarpal bone ; 1, anconeus muscle ; 2,
surface of the flexor digitorum profundus, exposed
by the removal of the aponeurotic tendon of 3, the
flexor carpi ulnaris ; 4, extensor carpi radialis
brevior, and 5, the cut tendon of the extensor carpi
radialis longior, both descending to their insertion at
e, into the second and third metacarpal bones ; 6,
extensor ossis metacarpi pollicis; 6', its insertion
into the first metacarpal bone ; 7, extensor primi
interned ii pollicis ; 7', its insertion into the base of
the first phalanx ; 8, extensor secundi internodii
pollicis ; 8', its insertion into the base of the last
phalanx ; 9, extensor indicis ; 9', its junction with
the tendon of the common extensor, which is cut
short : in the metacarpal spaces the four dorsal
interossei muscles are represented, the tendons of
the common extensor having been removed ; and at
10, the insertion of the second and third dorsal
iuterossei, by a triangular expansion, into the tendon
of the extensor communis, as well as the mode of
insertion of that tendon into the middle and last
phalanges, are shown.
On the back of the hand the tendon of the
ring-finger gives off two processes, one on
each side, which pass obliquely downwards
to join the tendons of the middle and little
fingers : in consequence of this arrange-
ment it follows that, if those two fingers be
flexed, the tendon to the ring-finger is held
downwards, and it becomes impossible to
extend that finger by the action of the muscle.
The tendon of the index-finger is only united
to that of the middle finger by a loose, transverse, semitransparent band of
fibres, and is free in its action. A synovial membrane invests the tendons
of this muscle as they pass under the annular ligament.
The extensor minimi digiti is a slender muscle which is placed between the
extensor communis digitorum and the extensor carpi ulnaris, and arises 1 y
DEEP EXTENSORS OF THE FINGEHS. 223
means of a thin tendon in common with the extensor cornmunis. The
tendon in which it ends occupies a groove between the radius and ulna,
passing through a ring in the annular ligament appropriated to itself, and
joins the fourth digital tendon of the common extensor.
The extensor carpi ulnaris, the most internal of the muscles descending on
the back of the forearm, arises from the external condyloid eminence of the
humerus by the common tendon and from a prolongation of that structure ;
from the posterior border of the ulna, below the anconeus, for about the
middle third ; and from the fascia of the forearm. The muscular fibres
derived from these sources incline somewhat inwards, and end in a tendon,
which runs through a special groove in the carpal end of the ulna and a
separate sheath in the annular ligament, and is inserted into the base of the
metacarpal bone of the little finger on its posterior aspect.
The deep- seated muscles on the back of the forearm are five in number,
the supiuator brevis, the three extensors of the thumb and the extensor of
the index finger.
The supinator radii brevis arises from the external lateral ligament of the
elbow-joint, and from the annular ligament of the radius; also from a rough
depression below the sigmoid cavity of the ulna, and from the outer border
of that bone for two inches. The fibres of the muscle, derived from these
points of attachment, as well as from a tendinous expansion on the surface,
pass obliquely round the upper part of the radius, covering it closely except
at the inner bide, and are inserted into that bone for rather more than a
third of its length, passing down to the upper margin of the insertion of
the pronator teres.
The posterior interosseous nerve passes through the fibres of this muscle.
The extensor ossis metacarpi pollicis (abductor longus pollicis, Alb.)
arises from an elongated depression on the radial side of the posterior
surface of the ulna below the origin of the supinator brevis, from a similar
extent of surface of the radius below the insertion of the same muscle, and
from the interosseous membrane between. Thence descending obliquely
outwards it ends in a tendon, which passes in company with the extensor
primi internodii pollicis through the groove on the outer border of the
lower extremity of the radius, and is inserted into the base of the meta-
carpal bone of the thumb.
The upper part of this muscle is concealed by the common extensor, but it becomes
superficial beneath, and together with the next muscle crosses the tendons of the
radial extensors of the carpus, conceals the insertion of the supinator longus, and,
beneath the extremity of the radius, crosses the radial artery.
The extensor primi internodii pollicis (extensor minor pollicis, Alb.)
lies close to the lower border of the extensor ossis metacarpi, and is much
smaller than that muscle ; it arises from the interosseous ligament and the
radius near the middle of the forearm ; its tendon accompanies that of the
extensor ossis metacarpi through the same compartment of the annular
ligament, and passes on to be inserted into the proximal end of the first
phalanx.
The extensor secundi internodii pollicis (extensor major pollicis, Alb.),
much larger than the extensor primi internodii, which it overlaps, arises
immediately below that muscle from the lower half of the shaft of the ulna,
and from the interosseous ligament at its lower end for about an inch. Its
224
MUSCLES OF THE UPPER LIMB.
fibres end in a tendon, which occupies the narrow oblique groove in the
middle of the posterior surface of the carpal end of the radius, and is bound
down in a separate compartment of the annular ligament ; it is inserted
into the base of the terminal phalanx of the thumb.
The groove which lodges the radial extensors of the carpus intervenes between
those which lodge the tendon of this muscle and the tendons of the other extensors
of the thumb.
A part of the tendon of the extensor ossis metacarpi is often found to terminate in
the upper end of the abductor pollicis. The extensor primi internodii is not unfre-
quently united with the extensor of the metacarpal bone, only a slender tendinous
filament reaching the first phalanx. A portion of the extensor secundi internodii has
been found attached to the first phalanx.
Fig. 184. Fig. 184. SUPERFICIAL MUS-
CLES AND TENDONS ON THE
BACK OF THE WRIST AND
HAND (After Bourgery). i
The posterior annular liga-
ment of the wrist is represented.
1, lower part of the extensor ossis
metacarpi pollicis ; 1', its inser-
tion ; 2, extensor primi inter-
nodii pollicis ; 2', its insertion ;
3, 3', tendon of the extensor se-
cundi internodii pollicis ; 4,
lower part of the extensor corn-
munis digitorum, before passing
below the posterior annular
ligament; 4', slip of this tendon
descending on the dorsum of
the middle finger, where it re-
ceives the insertion of the se-
cond and third dorsal inter-
ossei ; 4", division of the tendon
into three portions, of which the
median is inserted into the
second phalanx, the two lateral
passing on to be inserted into
the terminal phalanx ; the
union of the tendons of the
third, fourth, and fifth fingers is
shown ; the slighter union which
frequently exists between the
tendons of the second and third
fingers is not represented in
the figure j 5, extensor minimi
digiti ; 5', its junction with the
slip of the common extensor ;
6, placed on the lower end of the ulna, points to the extensor carpi ulnaris ; 6', insertion
of this muscle into the base of the fifth metacarpal bone ; 7, part of the flexor carpi ulnaris ;
8, placed on the os magnum, points to the insertion of the extensor carpi radialis brevior ;
8', placed on the base of the second metacarpal bone, points to the insertion of the
extensor carpi radialis longior ; 9, tendon of the extensor indicis, emerging from below the
annular ligament, to pass towards the index finger; 10, small part of the adductor
pollicis, and deep head of the flexor brevis pollicis ; 11, first dorsal interosseous or abductor
indicis : in the other three interosseous spaces are seen in succession from the radial side
inwards the insertion of the first palmar, second dorsal, third dorsal, second palmar,
fourth dorsal, and third palmar interossei muscles ; 12, abductor minimi digiti.
The extensor indicis (indicator) arises from the posterior surface of the
ulna for three or four inches below the middle. The tendon passes with
MUSCLES OF THE HAXD. 225
the common extensor through a compartment of the annular ligament,
comes into contact with the tendon from that muscle destined for the index
finger, and unites with it to form the expansion already described.
Fig. 185. TRANSVERSE SECTION OF THE RIGHT
HAND BETWEEN THE CARPUS AND META-
CARPUS, SHOWING THE ANTERIOR ANNULAR
LIGAMENT OP THE CARPUS, AND THE PLACES
OP THE VARIOUS EXTENSOR AND FLEXOR
TENDONS, SEEN FROM THE DISTAL SIDE. 4
This figure is also designed to show the
transverse arch formed by the second row of
carpal bones, a, metacarpal articular surface
of the trapezium for the metacarpal bone of
the thumb; a', palmar ridge of the trapezium ;
b, articular surface of the trapezoid bone for
the second metacarpal bone ; c, the surface
of the os magnum for the middle metacarpal ;
d, the surface of the unciform for the fourth, and e, that for the fifth metacarpal
bone ; e', unciform process ; between a' and e', the cut edge of the annular ligament
is represented, the ends attached to the projecting parts of these bones, and sending
another process towards the trapezium at 11, by which the tendon, of the flexor carpi
radialis is enclosed in the groove of the trapezium ; 1, tendon of extensor ossis metacarpi
pollicis ; 2, extensor primi internodii ; 3, extensor secundi internodii ; 4, extensor
indicia; 5 and 6, long and short radial extensors of the carpus; 7, the four divi-
sions of the tendon of the common extensor of the fingers, the middle two belong to
the third aud fourth fingers ; 8, extensor minimi digiti ; 9, extensor carpi ulnaris ;
10, flexor carpi radialis; 11, flexor longus pollicis; 12, the first on the ulnar side of
the tendons of the flexor superficial digitorum ; 13, the same of the flexor profundus ;
14, the median nerve; 15, points to the middle of the cut margin of the palmar
aponeurosis stretched across the annular ligament ; 16, the fibres of the palmaris brevis
muscle ; 17, cut surface of the muscles of the ball of the thumb ; 18, muscles of the
little finger.
MUSCLES OF THE HAND.
Besides the tendons of the long muscles and the lumbricales already
described, there are placed in the hand one superficial muscle called
palmaris brevis, the short muscles of the thumb and little finger, and the
interossei muscles.
The palmaris brevis is a thin flat subcutaneous muscle, which arises from
the inner margin of the palmar fascia and annular ligament ; its fibres pro-
ceed transversely inwards, and are inserted into the skin along the inner
border of the palm.
The palmaris brevis crosses the muscles of the little finger and covers the ulnar
artery and nerve. It is -subject to considerable variation in its breadth and thickness,
consisting sometimes of only a few scattered fibres.
MUSCLES OF THE THUMB The fleshy mass which forms the thenar pro-
minence, or ball of the thumb, consists of four muscles.
The abductor pollicis (abductor brevis pollicis, Alb.), superficial and flat,
arises from the annular ligament and from the ridge of the os trapezium,
and, proceeding outwards and forwards, is inserted by a tendon into the
radial border of the first phalanx of the thumb at its base.
The opponens pollicis, placed behind the abductor, arises from the
annular ligament and from the os trapezium and its ridge, and is inserted
into the whole length of the metacarpal bone of the thumb at the radial
border.
Q
226
MUSCLES OF THE UPPER LIMB.
The flexor brevis pollicis arises by two heads, a superficial and a deep.
The superficial head is attached to the outer two-thirds of the annular
Fig. 186.
Fig. 187.
Fig. 186. MUSCLES AND TENDONS OF THE
PALMAR ASPECT OF THE HAND. ^
A portion of the tendons of the superficial
flexor has been cut away to show those of the
deep flexor and the lu rubricates. 1, tendon of
the flexor carpi radialis, cut short near the
place where it enters the canal in the outer
attachment of the annular ligament of the
carpus ; 2, tendon of the flexor carpi uluaris,
inserted into the pisiform bone ; 3, anterior
annular ligament of the carpus ; 4, abductor
pollicis ; 5, opponens pollicis ; 6, 6, flexor
brevis ; 7, adductor pollicis ; 8, abductor
minimi digiti ; 9, flexor brevis minimi digiti ;
10, lumbricales, passing to their insertion on
the radial side of the four fingers.
ligament and to the os magnum : the
deep head is attached to the os trape-
zoides and os magnum, to the sheath
of the flexor carpi radialis, and to the
bases of the second and third meta-
carpal bones. From the superficial and
deep heads of origin two strong masses
of fibres proceed which, becoming tendi-
nous, are attached to the outer and inner
sesamoid bones respectively, and are
inserted into the sides of the base of
the first phalanx of the thumb ; the
outer head is also joined by a con-
siderable fasciculus from the deeper
origin ; the inner head is inserted con-
jointly with the adductor pollicis. The
two tendons of insertion, with the sesa-
Fig. 187. DEEP MUSCLES OF THE PALM OF
THE HAND. ^
The abductor pollicis and abductor minimi
digiti, together with the anterior annular
ligament and the long flexor tendons in the
palm, have been removed ; in the fore-finger
the tendons of both the superficial and deep
flexors remain ; in the other fingers the ten-
dons of the superficial flexor have been
removed. 1, pronator quad rat us muscle ;
2, opponens pollicis ; 3, flexor brevis pollicis;
4, adductor pollicis ; 5, opponens minimi
digiti ; 6, unciforra bone ; 7, 8, interosseous
muscles.
moid bones, play over the grooved surfaces of the first metacarpal bone.
The tendon of the long flexor lies between the heads of origin, and grooves
the surface of the muscle as it passes between the tendons of insertion.
The adductor pollicis arises from the anterior two thirds of the palmar
surface of the metacarpal bone of the middle finger, and is inserted into the
MUSCLES OF THE LITTLE FIXGER.
227
base of the first phalanx of the thumb along with the inner tendon of the
short flexor.
MUSCLES OF THE LITTLE FINGER. The fleshy mass at the inner border of
the hand (hypothe)iar prominence) consists of three muscles passing to the
little finger.
The abductor minimi digiti arises by tendinous fibres from the pisiform
bone and the inserted tendon of the flexor carpi ulnaris, and is inserted
into the base of the first phalanx of the little finger on the ulnar border.
The flexor brevis minimi diyiti, separated at its origin from the abductor
muscle by a small interval through which pass the deep palmar branch of the
ulnar nerve and the communicating branch of the ulnar artery, arises from
the front of the annular ligament, and from a tip of the hooked process
of the unciform bone, and is inserted into the base of the first phalanx of
the little finger, in connection with the preceding muscle. This muscle is
sometimes absent, or becomes incorporated with the abductor.
The opponens minimi digiti (adductor ossis metacarpi digiti minimi, Alb.)
arises from the annular ligament and the unciform process, and is inserted
into the ulnar border of the fifth metacarpal bone in all its length.
Fig. 188.
Fig. 188. THE RIGHT HAND FROM BEHIND, SHOWING THE DORSAL INTEROSSEOUS
MUSCLES, f
The tendons of the extensor muscles have been removed as far as the distal ends
of the metacarpal bones. 1, 2, 3, and 4, the interossei muscles, in order from the radial
side inwards ; their expanded insertion in connection with the extensor tendons, is shown
upon the first phalanges.
Fig. 189. THE RIGHT HAND FROM BEFORE, SHOWING THE PALMAR INTEROSSEI
MUSCLES, f
1, 2, and 3, refer to the first, second, and third palmar interosseous muscles.
The INTEROSSEOUS MUSCLES occupy the intervals between the metacarpal
bones. They are seven in number, all of them more or less visible from the
palmar aspect, and they are divided into two sets, viz., those which are best
seen on the dorsal aspect of the metacarpus, and those which are seen only
in the palm. Their disposition is most easily understood by reference to
their action.
Q2
228 MUSCLES OF THE UTTER LIMB.
The dorsal interossei muscles separate the fingers from the middle line of
the hand ; they are four in number, each occupying one of the spaces between
the metacarpal bones. They are named numerically from without inwards.
Each muscle arises from both the metacarpal bones between which it is
placed, but most extensively from that supporting the finger upon which it
acts, and the fibres converge pennately to a common tendon in the middle.
Each terminates in a tendon, which is inserted partly into the base of the
first phalanx, and partly into the tendon of the common extensor muscle
on the dorsum of the same part of the finger. Two dorsal interossei are
inserted into the middle finger and draw it to either side ; of the remaining
muscles one passes to the radial side of the index-finger, and the other
to the ulnar side of the ring-finger ; they withdraw those fingers from the
middle line of the hand.
The first dorsal interosseous muscle or abductor indicis is larger than the
others ; its outer and larger head of origin arises from the proximal half of
the ulnar border of the first metacarpal bone, the inner is attached to the
whole length of the second metacarpal bone, and between these heads there is
left superiorly an interval wider than in the other dorsal interosseous muscles.
Between the heads of the abductor indicis the radial artery passes forwards to the
palm of the hand ; between those of the other dorsal interossei small perforating
arterial branches are transmitted.
The three palmar interossei are adductors, drawing the index, ring, and
little fingers towards the middle line of the hand. They are visible only
from the palmar aspect of the hand, each one being attached to the metacarpal
bone of the finger on which it acts : they terminate, like the dorsal muscles,
in small tendons inserted partly into the base of the first phalanx at the
side, and partly into the extensor tendon. The first palmar interosseous
muscle bolongs to the ulnar side of the index-finger ; the others are placed
on the radial sides of the ring and little fingers.
The interosseous muscles are subject to some variation in their number and form.
An additional palmar interosseous muscle, going to the dorsal aponeurosis of the
thumb, is described as frequent by Henle and Wood. (See J. Wood, " On some
varieties in Human Myology," in the Proc. of the Roy. Soc. for 1864, p. 302.)
ACTIONS OF THE MUSCLES OF THE FOREARM AND HAND.
The muscles of the forearm may be distinguished according to their actions as
pronators and supinators, flexors and extensors of the wrist, and long flexors and
extensors of the fingers : those of the hand are flexors, adductors, abductors,
opposers, and partially also extensors of the fingers.
Pronation is effected by the pronator quadratus and pronator teres : the flexor
carpi radialis also contributes slightly to this movement. The pronator teres is fitted
to flex the elbow when pronation has been completed, or when it is prevented by
antagonistic muscles.
Supination is effected principally by the supinator brevis. The supinator longus
is not so advantageously situated to accomplish this action ; it is principally & flexor
of the elbow, acting, however, only after that movement has been begun by the
instrumentality of other muscles : in the extended and supinated condition of the
forearm it assists in binding the radius more firmly to the humerus.
Flexion of the wrist is produced by the radial and ulnar flexors of the carpus, and
is aided by the flexors of the fingers when the action of those muscles on the fingers
is either completed, or is opposed by any resistance, as when the over-extended hand
is pressed against a surface in pushing, or in the support of the body.
Extension of the wrist, in a similar manner, is accomplished not only by the three
muscles specially devoted to that function, but also by the extensors of the fingers.
FASCLF OF THE UPPER LIMB. 229
The flexors arising from the inner condyloid eminence of the humerus, and the
extensors arising from the outer condyloid eminence, are most advantageously situated
for acting on the other joints over which they pass, when the position of the elbow-
joint is such as to keep them most on the stretch ; but when flexion of those other
joints is either completed or opposed, they have also some effect, though not great,
upon the elbow-joint itself.
Thejlexores sublimis and mofundus and the lumbricales muscles are the flexors
respectively of the second, third, and first phalanges. The lumbricales, while they
flex the first phalanx, at the same time, by virtue of their connection with the extensor
tendons, extend the other phalanges, thus causing the fingers to pass through the
movement which they undergo in making the hair-stroke in writing. They are
assisted in this action by the interossei.
When the thumb is opposed to the other fingers, the metacarpal bone is drawn
forwards, not only by the opponens muscle, but also by the abductor, and by the flexor
brevis, acting when the first phalanx is flexed, or when it is fixed by the extensor
primi internodii. The precise action of the abductor is to draw the thumb forwards
and outwards. The extensor ossis metacarpi is entirely an abductor, as indicated by
the name given to it by Albinus. The extensor primi internodii likewise is an
abductor as well as an extensor of the first phalanx. The extensor secundi internodii
extends both phalanges and draws the metacarpal bone directly backwards. The
adductor and the inner fibres of the flexor brevis adduct the thumb. A combination
of the actions of the different muscles in succession produces circumduction.
The little finger is withdrawn from the others by its abductor, as the ring-finger is
withdrawn from the middle finger by the fourth dorsal interosseous muscle ; and the
abductor, acting with the long flexors, likewise assists the flexor brevis in keeping the
first phalanx firmly down in grasping.
The palmaris longus has but little action, and that is exerted in tightening the
palmar fascia. The palmar is brevis increases the hollow of the hand by pulling on
the integument on the inner side, so as to increase the hypothenar prominence.
FASCIAE OF THE UPPER LIMB.
The superficial fascia covering the muscles which pass from the trunk to
the shoulder and upper limb, forms a complete investment of the upper part
of the trunk, being continuous with that of the neck superiorly, and with
those of the abdomen and hip inferiorly, and extending from the shoulder
and over the arm, forearm and hand, so as to cover the whole limb. In the
subcutaneous tissue of the upper limb bursse are usually found placed over
the acromion, the olecranon, and the knuckles.
The superficial fascia of the pectoral region encloses the mammary
gland, covering it both in front and behind, and sending strong septa iu
between its lobes. Processes likewise extend from the investment of the
gland between the masses of fat forwards to the skin and nipple, and these,
from the support which they afford to the gland, have been named by Sir
Astley Cooper ligamenta suspensoria. (" On the Anatomy of the Breast,"
London, 1840.)
The superficial fascia of the arm is most distinct opposite the bend of the
elbow, where the superficial veins contained within its laminae are numerous
and large. In the palm of the hand, on the contrary, the subcutaneous
tissue forms a firm connecting medium between the skin and a strong
aponeurosis named the palmar fascia : it consists of a network of fibres pass-
ing between those two structures, dividing the subcutaneous fat into small
granules, so as to prevent the skin from shifting to any considerable extent.
Of the deep fascice the following parts require special notice. The costo-
coracoid membrane is a distinct layer of firm fascia whose strongest fibres,
distinguished sometimes as the costo-coracoid ligament, extend from the
coracoid process to the first rib at the origin of the subclavius muscle, and
230 FASCIAE OF THE UPPER LIMB.
which conceals that muscle from view. Superiorly it is attached to the
clavicle ; inferiorly it is narrowed like a funnel, and becomes thinner as it
descends upon the surface of the axillary vessels, forming the anterior part
of the sheath of those vessels, while the posterior part is formed by a deep
process of the cervical fascia.
The axillary fascia is a strong membrane stretched across the axilla, and
so disposed as to maintain the skin in position across that hollow. Beneath
the pectoralis major muscle is a layer of fascia attached to the chest in front
of the costo-coracoid membrane : it divides into two layers to enclose the
pectoralis minor, and, these reuniting, it continues to pass outwards, forming
a strong membrane in the angle between the pectoralis minor and short head
of the biceps muscle; lower down it is joined by the superficial investment
of the pectoralis major, which is folded round the margin of that muscle, and,
thus strengthened, it slopes outwards and backwards to the inferior border
of the scapula, where it is joined by the sheaths of the latissimus dorsi
and teres major muscles. The deepest hollow of the axillary fascia is formed
where the layer from the surface of the pectoralis major joins that from the
pectoralis minor ; and in that part especially it is perforated by numerous
lymphatics. At the angle occupied by the large vessels and nerves of the
limb, it is continuous with the sheath of the vessels and with the aponeu-
rosis of the arm. The density of this fascia offers a considerable obstacle to
the progress outwards of axillary abscesses.
The aponeurosis of the upper limb is a strong sheath which binds together
all the muscles of the arm and forearm. A strong and somewhat isolated
portion, bound down to the vertebral and axillary margins and to the lower
border of the spine of the scapula, covers the infraspinatus and teres minor
muscles as far as they are left uncovered by the deltoid muscle. On reaching
the posterior border of the deltoid muscle, this aponeurosis divides into two
layers, of which the deeper is continued beneath the deltoid to the shoulder-
joint, and the more superficial forms a thin aponeurotic covering of that
muscle, becoming more and more slender as it passes forwards.
The aponeurosis of the arm is composed chiefly of transverse fibres, held
together by others having an oblique or longitudinal direction ; it is thin over
the biceps muscle, stronger where it covers the triceps, and particularly
dense as it approaches the outer and inner condyloid eminences of the
humerus. It is pierced on the inner side of the limb by the basilic vein,
at some distance below the axilla. It is attached to the shaft and condyloid
eminences of the humerus by the two processes next to be described.
The external and internal intermuscular septa are two fibrous partitions
which bind the aponeurosis of the arm to the humerus, and with which the
neighbouring muscles of the arm are intimately connected. The external inter-
muscular septum extends upwards from the outer condyloid eminence along
the outer lateral ridge to the insertion of the deltoid, from which it receives
tendinous fibres. It is pierced from behind forwards by the musculo-spiral
nerve and superior profunda artery. The internal septum, much stronger,
extends along the ridge from the inner condyloid eminence to the insertion
of the coraco-brachialis muscle. It is traversed from before backwards by the
ulnar nerve and by the inferior profunda and anastomotic arteries.
At the bend of the elbow the aponeurosis is closely connected with the
periosteum covering the condyloid eminences of the humerus and the ole-
cranon process of the ulna ; arid it is strengthened by tendinous fibres sent
from the triceps and biceps muscles.
The apcneurosis of the forearm, like that of the arm, is composed principally
FASCLE OF THE FOREARM AND HAXI). 231
of circular fibres, strengthened, however, by longitudinal and oblique fibres
descending from the condyloid eminences of the humerus, from the ole-
cranon, and from the superficial insertion of the biceps muscle. It is
attached along the subcutaneous margin of the ulna, and may be conveniently
divided into an anterior and a posterior part.
The anterior part of the aponeurosis of the forearm is much weaker than
the membrane on the posterior aspect of the limb. It is continued below
into the anterior annular ligament. In the hollow immediately below the
bend of the elbow, it presents a small oval aperture for the transmission of
a short communicating branch between the superficial and the deep veins of
the forearm. It increases in density towards the band ; and a little above
the wrist affords a sheath to the tendon of the long palmar muscle, which
passes over the annular ligament to be inserted into the narrow end of the
palmar fascia. Several white lines seen on the surface of the fascia mark
the positions of the septa between the 'origins of the muscles descending
from the inner condyloid eminence, which are continuous with it. Between
the superficial and the deep flexor muscles, another layer of fascia is stretched
from side to side; it is stronger below than above, where it generally
consists of little more than thin connective tissue.
The anterior annular ligament of the carpus, previously described at
p. 144, is continuous at its upper margin with the fascia of the forearm,
and receives some fibres from the tendon of the flexor carpi ulnaris : the
lower margin is connected with a deep part of the palmar fascia, and gives
origin in part to most of the short muscles of the thumb and little finger.
This structure may be considered in some measure as a developed portion of
the fascia of the wrist, and also as a ligament.
The posterior portion of the aponeurosis of the forearm, much thicker than
the anterior, is intimately connected with the strong septa between the
several superficial muscles, and sends off transversely a thin membrane to
separate the superficial from the deeper group of muscles. Approaching the
back of the wrist, the transverse fibres increase in number and strength, and
these, being stretched from the outer margin of the radius on one side to
the cuneiform and pisiform bones and the palmar fascia on the other,
constitute the posterior annular ligament of the carpus (see p. 144). This
structure is attached not only to the points now indicated, but is likewise
connected to the several longitudinal ridges on the posterior surface of the
radius, and thus converts the intermediate grooves into fibro-osseous canals
to lodge the tendons of the extensor muscles. There are six separate spaces
so enclosed, and each is lined by a distinct synovial sac. The outermost space
corresponds with the groove on the outer side of the radius, and gives
passage to the extensores ossis metacarpi and primi internodii pollicis, the
next three, placed on the back of the radius, give passage respectively to
the two radial carpal extensors, the extensor secundi internodii pollicis, and
the common extensor of the fingers, with the extensor indicis accompanying
it ; between the radius and ulna is the compartment for the extensor minimi
digiti ; and resting in the groove on the back of the ulna is that for the
extensor carpi uluaris.
On the back of the hand there is only a thin layer of fascia prolonged from
the posterior annular ligament over the extensor tendons, and separating
them from the superficial veins and nerves. Beneath this ure special fibrous
membranes stretched over the interossei muscles.
On the palm of the hand is the palmar fascia, a strong aponourosis,
consisting of a central and two lateral portions. The lateral parts are very
232 DORSAL MUSCLES OF THE TRUNK.
tliin ; they afford a delicate but firm covering to the muscles of the thumb
and little finger respectively. The central portion is one of the strongest
fascise of the body. Occupying the interval between the thenar and
hypothenar eminences and expanding towards the fingers, it has a somewhat
triangular or fan-like form. The narrow end of the fascia, thicker than any
other part, and composed of close parallel fibres, is connected by its deep
surface with the anterior annular ligament, and is continuous superiorly
with the tendon of the palrnaris longus, when that muscle is present ; the
broader portion, becoming thinner and flatter as it advances towards the
fingers, has a much more irregular and interlaced texture, and adheres
more closely to the skin of the palm. Near the lower part of the palm it
separates into four processes, each of which again subdivides iuto two slips
next the root of a corresponding finger; and the bundles of fibres thus
separated, dipping one on each side of the flexor tendons belonging to the
finger, are attached to the margins of the metacarpal bone and to the trans-
verse ligament which binds the metacarpal bones to each other. From the
centre of each process longitudinal fibres are continued to the skin as far
forward as the root of the finger. These digital processes of the palmar
fascia are held together by irregular transverse fibres, which lie immediately
under the skin, and serve to give great additional strength at the points of
divergence.
MUSCLES OF THE TRUNK.
The muscles passing between the trunk and the upper limb having been
already described, those which belong exclusively to the trunk itself will now
be treated of under the three divisions of, 1. Dorsal muscles, extending
throughout the whole length ; 2. Thoracic muscles, including the
diaphragm ; and 3. Abdominal and Perineal muscles.
DORSAL MUSCLES OF THE TRUNK (MUSCLES OF THE BACK).
The muscles to be described under the above head, taken as a whole,
occupy more or less deeply the hollow between the entire middle line of the
vertebral spines and the prominences formed towards the sides by the
mastoid processes, the transverse cervical processes, the most projecting
parts of the ribs, and the crest of the ilium, and they extend from the superior
curved line of the occipital bone to the lower part of the sacrum. Some
consist of comparatively limited portions of muscular substance, and occupy
only certain parts of the extensive region now referred to ; others extend
either continuously or by the serial repetition of similar fasciculi, through-
out the greater part of it. These muscles, together with those in the same
region which belong more properly to the upper limb, have been frequently
described as constituting six successive layers ; but the limits of several of
these layers do not present very marked natural planes of separation, and
it will be sufficient for the purpose of description to arrange those which
fall properly within the present section, according to the main characteristics
of their form and position, into the following groups: viz., a, the posterior
serrati muscles ; 6, the splenius and long erectors of the spine ; c, the
complex us and transverse spinales ; d, the iuterspiuales and intertrans-
versales ; e, the short cranio-vertebral muscles. Of these muscles those
included in the first two groups may be considered as having their fibres
passing outwards from the middle ; those in the third group as having
their fibres passing inwards ; those of the fourth group as having their fibres
POSTERIOR SERRATI MUSCLES.
233
passing in a nearly vertical direction ; and those of the fifth group, confined
to the upper part of the vertebral column and to the head, may be looked
upon as combining some examples of the others.
SERRATI MUSCLES. The serratus posticus superior is a thin flat muscle,
which arises from the lower part of the ligamentum nuchse and from the
spines of the last cervical and two or three upper dorsal vertebrae by a flat
tendon inclining downwards and outwards, and forming about a third of the
length of the muscle ; it is inserted by four fleshy digitations into the
second, third, fourth, and fifth ribs, a little beyond their angles. It \A
directed obliquely downwards and outwards, resting on the deep muscles
and the angles of the ribs. The muscle is covered, excepting at its superior
border, by the rhomboid and levator anguli scapulae muscles.
The serratus posticus inferior, broader and stronger than the preceding
muscle, passes outwards and upwards to the four lowest ribs ; it arises,
by a thin aponeurotic membrane, which forms part of the posterior layer of
the lumbar aponeurosin, from the spinous processes and interspinous liga-
ments of the two last dorsal and two or three upper lumbar vertebrae.
The outer part of the muscle forms a fleshy lamella inserted by four digita-
tions into the lower burder of the last four ribs. The uppermost of those
digitations is very broad, and covers in part the second ; the last, varying
in size with the length of the twelfth rib, is entirely concealed by the rest
of the muscle (see fig. 171, p. 202). The serratus inferior is covered by
the latissimus dorsi, and its aponeurotic part is firmly united for some
distance with the tendon of that muscle.
Fig. 190. DORSAL MUS-
CLES OF THE UPPER
PART OF THE TRUNK.
I, first ; VI, sixth dor-
sal vertebra ; 1 , upper part
of the complexus major
muscle ; 2, splenius capi-
tis ; 3, 3', splenius colli ;
4, serratus posticus supe-
rior ; 5, upper part of the
longissimus dorsi ; 5', the
same continued up on the
left side into the transver-
saliscervicis ; 5", 5", on the
right side the transversa-
lis cervicis spread out
from its attachments ; 6,
upper insertions of the
sacro-lumbalis and acces-
sorius ; 6', the same con-
tinued up on the left side
into the asceudens cer-
vicis; 5", upper, 6", lower
end of the ascendens cer-
vicis of the right side
spread out from its attach-
ments ; 7, small part of
the spinalis dorsi ; 8,
right levator anguli sca-
pulae, dissected out from
its attachments ; 8', on
the left side, the upper
part of the levator sea-
pulse, shown in its relation to the splenius colli ;
on the right side.
Fig. 190.
three of the levatores costarurn shown
234 DORSAL MUSCLES OF THE TRUNK.
ACTIONS. The serratus posticus superior elevates the upper ribs, and is therefore to
be regarded as a muscle of inspiration. The serratus inferior acts directly as a
depressor of the lower ribs, and may aid either in expiration or inspiration; in
expiration by acting in concert with the muscles which depress the higher ribs ; in
inspiration by fixing the lower ribs and giving firmness to the origin of the
diaphragm.
SPLENITJS. The splenius muscle is so named from its having the form of
a strap, which binds down the parts lying under it. It is attached superiorly
in part to the cervical vertebrae, in part to the skull, and is described
accordingly under two names.
a. The splenius colli is attached inferiorly to the spinous processes of the
third, fourth, fifth, and sixth dorsal vertebrae, and superiorly along with the
slips of the levator anguli scapulae to the transverse processes of the first two
or three cervical vertebrae.
6. The splenius capitis, broader and thicker than the preceding, arises
from the spines of the seventh cervical and two upper dorsal vertebrae, and
from the ligamentum nuchae as high as the third cervical vertebrae. It is
inserted into the lower and back part of the mastoid process, and into the
outer part of the superior curved line of the occipital bone.
The splenius is covered by the trapezius, the rhomboid, and the serratus posticus
superior ; and on the cranium by the sterno-mastoid. It conceals, in part, the
complexus and trachelo-mastoid.
ERECTOR SPINJE. The erector spince may either Ve regarded as one large
composite muscle, or as consisting of seven distinct muscles. Viewed as
one muscle it may be conveniently considered as formed of three columns,
of which the inner, or that next the spine, is comparatively slender ; the
outer and inner columns of the remaining thicker mass consist each of a
large lower muscle and of two successive slender continuations in an upward
direction ; and to all these seven portions, or muscles, distinct names have
been given.
The erector spinae takes origin inferiorly as a common mass, tlie outer
part of which is muscular, while the inner and larger part is tendinous.
The muscular portion arises from the posterior fifth of the crest of the ilium ;
the tendinous portion arises from the back part of the ilium, the lower and
back part of the sacrum, and the sacral and lumbar spines ; it is inseparably
united below with the lumbar aponeurosis, and is prolonged upwards on the
surface of the muscular part, concealing the multifidus spinae. The division
of the larger part into an external and internal column takes place below the
level of the last rib.
a. The ilio-costalis (Theile) or sacro~lumbalis > the main muscle of the outer
column, is fleshy inferiorly, springing from that part of the common origin
which proceeds from the crest of the ilium ; it ends in a series of tendons
which incline slightly outwards, and are inserted one into each of the six or
seven lowest ribs at their angles.
b. The musculus accessories ad ilio-costalem (ad sacro-lumbalem) is a con-
tinuation of the preceding muscle. It arises by flat tendons from the upper
margins of the lower six or eight ribs, internal to the tendons of the ilio-
costalis, and ends superiorly by continuing the series of those tendons to the
upper ribs.
c. The cervicalis ascendens consists of slips in serial continuation with
those of the musculus accessorius, takiog origin from four or five of the
ERECTOR SPIX.E MUSCLE. 235
highest ribs, and inserted into the transverse processes of three cervical
vertebrae, usually the fourth, fifth, and sixth. Its insertions are intimately
connected with those of the transversalis cervicis.
d. The longissimus dorsi, the main muscle of the inner column of the
erector spinse, is both larger and longer than the ilio-costalis, its original
fibres passing as high as the first dorsal vertebra. Internally it is closely
connected on the surface with the spinalis dorsi, from the lower part of
which it generally receives one or more tendinous slips. When those slips
and the tendons of origin from the lumbar spines are cut through, the inner
surface of the muscle can be brought into view. The longissimus dorsi
presents two series of insertions. The inner row of insertions is a series of
rounded tendons attached to the inferior tubercles of all the transverse pro-
cesses of the dorsal, and the accessory processes of the lumbar vertebras.
The outer insertions form in the dorsal region a series of thin processes
attached to the nine or ten lowest ribs, sometimes more or fewer, and in
the lumbar region are attached by fleshy slips to the whole length of the
transverse processes, and beyond these to the lumbar fascia arising from
them.
e. The transversalis cervicis prolongs upwards the column of fibres of the
longissimus dorsi. It arises from the internal tubercles of the transverse
processes of the four or five highest dorsal vertebrae, and occasionally the
last cervical, and is inserted into the posterior tubercles of the transverse
processes of five cervical vertebrae from the second to the sixth inclusive.
It always receives a slip of the original fibres of the longissimus dorsi.
/. The trachelo-mastoid muscle, which may be regarded as the con-
tinuation of the longissimus dorsi to the head, arises in close connection
with the trans versalis cervicis from the upper dorsal transverse processes,
and also from behind the articular processes of the three or four lowest
cervical vertebrae, and, forming a tbiu flat muscle, passes to be inserted into
the posterior margin of the mastoid process, under cover of the splenius and
sterno-mastoid muscles. It is the only muscle which lies between the
splenius and complexus, and the only portion of the erector spinse concealed
by the former.
g. The spinalia dorsi is a long narrow muscle placed at the inner side of
the longissimus dorsi, and closely connected with it. It arises by several
tendons from the spines of the first two lumbar, and the two lowest dorsal
vertebrae, and is inserted into from four to eight of the higher dorsal spines.
It adheres closely to the semispinalis muscle upon which it lies.
ACTIONS. The gplenii and trachelo-mastoid muscles of both sides acting together
draw backwards the head and upper cervical vertebrae : when the muscles of one side
only act the extension is accompanied by lateral flexion and rotation, especially of the
head on the axis.
The greater part of the erector muscles of the spine, when those of both sides are in
action, bends backwards the vertebral column and trunk ; and these muscles co-
operate powerfully in almost every great muscular effort of the body or limbs. It is
the power of these muscles to straighten the back from the bent condition, of which a
measure is obtained by the muscular dynamometer; the amount of this varies in
adults of medium strength from SOOlbs. to 400lbs. By the action of the erector
muscles of one side a certain amount of lateral flexion and of rotation, which is
greatest in the chest, accompanies the extension. These muscles also, by their costal
attachments, if the spine be fixed, depress the ribs, and thus assist in expiration ; but
it is likewise conceivable that the cervicalis ascendens and musculus accessorius, in
acting from fixed points above, may have the effect of elevating the ribs.
236
DORSAL MUSCLES OF THE TRUXK.
Fig. 191.
Fig. 191. VIEW OP THE
DEEP MUSCLES OP THE
BACK, DESIGNED TO
SHOW SOMEWHAT DIA-
GRAMMATICAL!^ THEIR
ATTACHMENTS TO THE
VERTEBRAL COLUMN AND
RIBS. |
On the left side the seve-
ral parts of the erector spinse
are nearly in their natural
position, with the excep-
tion of the spinalis dorsi,
which is drawn out laterally
from the spines of the ver-
tebrae ; on the right side
the spinalis dorsi has been
entirely removed, the ilio-
costalis drawn to the outer
side so as to expose its
accessory muscle, and the
longissimus removed except-
ing small portions at its
insertions. Superiorly on
the left side, the trachelo-
mastoid and complexus
major are left neai'ly in
their natural positions ;
while, on the right side, the
trachelo-inastoid has been
entirely removed, and the
com plexus major, separated
from its occipital attach-
ment, has been spread out
to the side so as to stretch
its vertebral attachments.
a, occipital protuberance ;
b, mastoid process; c, bifid
spinous process of the axis
vertebra ; I, spinous pro-
cess of the first dorsal ver-
tebra and first rib ; VI,
sixth dorsal spine and trans-
verse process and sixth rib ;
XII, twelfth dorsal spine
and twelfth rib. On the left
side of the figure, 1, com-
plexus major muscle ; 2,
trachelo- mastoid ; 3, serra-
tus posticus superior, de-
tached from the vertebral
column and drawn upwards
from the ribs ; 4, 4, the
slips of attachment of the
serratus posticus inferior to
the four lower ribs; 5, three
blips of origin of the latis-
simus dorsi from the lower
ribs ; 5*, iliac origin of the
same muscle; +, common
origin of the longissimus
dorsi and ilio-costalis
from the ilium and sac-
rum, &c. ; 6, upper part of
the lon^issimus dorsi ; 0',
COMPLEXUS AND SEMISPINALES MUSCLES. 237
transversalis cervicis continued up from the longissirnus ; 7, ilio-costalis (sacro-
lumbalis), drawn slightly inwards to show the slips of insertion into the lumbar
fascia and the various ribs ; inside the costal insertions are seen the origins of the
accessorius; 7', the ascendens cervicis continued upwards from the accessorius ; 8, spinalis
dorsi. On the right side, 6 marks, in the lumbar region, the insertions of the longis-
simus dorsi into the upper four transverse processes (the insertion into the accessory pro-
cesses not being shown), in the dorsal region the narrower tendons of insertion into the
lower part of the dorsal transverse processes (the six lower only are represented); 6', the
series of insertions into nine ribs; 7, the ilio-costalis drawn outwards; 7', placed between
the lowest costal insertion of the ilio-costalis and the lowest origin of the accessorius ;
7", extension of the ascendens cervicis from the fifth rrb towards the neck ; 9, 9, semi-
spinalis colli; 10, 10, semispinalis dorsi; 11, 11, lower dorsal and lumbar parts of
the multifidus spinse, which appears again above the semispinalis colli, above the upper
9 ; 12, placed upon the eighth rib, levatores costarum, long and short ; 13, in the upper
part of the figure points by four lines to the rectus capitis posticus minor, rectus major,
obliquus superior, and oWiquus inferior muscles.
COMPLEXUS AND TRANSVERSO-SPINALES. The muscles of the complicated
group comprising the complexus semispinalis, and multifidus spince, present
the feature in common of ascending with an inward inclination, and are
thus distinguished from those last described. The most superficial, the
complexus, not usually included in this group, but obviously resembling the
others, has the longest and most vertical fibres, but is the shortest as a
whole, being limited to the upper dorsal and the cervical region ; the muscle
beneath it, the semispinalis, occupies the greater part of both these regions ;
while the multifidus spinse, extending from the sacrum to the axis, has the
shortest and most oblique fibres.
The complexus (complexus major} arises by tendinous points from the
transverse processes of the seven highest dorsal and the seventh cervical verte-
brae, and from the articular processes of four and sometimes five other cer-
vical vertebrae, together with the capsular ligament uniting them ; and it is
inserted into the large internal impression between the two curved lines of
the occipital bone. It is narrower above than below, and its inner margin
in the neck is in contact with the ligamentum nuchse. Above the middle
the muscle is partly crossed by a tendinous intersection. One interrupting
tendon in particular, on the inner side, is so constant that the fibres con-
nected with it, viz. , those ascending from the three or four lowest points of
origin, are often described separately, under the name of biventer cervicis :
this portion of the muscle is also frequently connected by a tendinous slip
with one or two of the spinous processes belonging to the last cervical or
first dorsal vertebra.
The complexus muscle is covered by the splenius, except at its lowest origins from
the dorsal vertebrae and at the internal portion of its upper extremity ; the trachelo-
mastoid and transversalis cervicis rest upon its series of origins, and the semispinalis
colli, the posterior recti, and the obliqui capitis, together with the deep cervical artery,
are concealed by it.
The semispinalis muscle consists of fibres exkn ling from transverse pro-
cesses to spines, each bundle crossing over about five vertebrae. It arises
from the internal tubercles of the transverse processes of numerous dorsal
vertebrae, usually the ten highest, and is inserted into spines from the axis
to the fourth dorsal vertebra inclusive. It is described in two parts.
a. The semispinalis colli is the part under cover of the complexus. It arises
from, the upper four or five dorsal transverse processes, and is inserted into
the spines of the cervical vertebrae from the second to the fifth inclusive, being
thickest at its insertion into the second vertebra.
238 DORSAL MUSCLES OF THE TRUNK.
b. The semispinalis dorsi, not covered by the complexus, consists of small
muscular bundles interposed between tendons of considerable length, and
forms an elongated thin stratum, especially towards its lower border. It
arises from the transverse processes of the dorsal vertebrae from the tenth to
the fifth inclusive, and is inserted into the spines of the last two cervical
and first four dorsal vertebrae.
The multifidus spince reaches from the sacrum to the axis vertebra, passing
up under cover of the semispinalis, and is much more largely developed
towards the lower than the -upper end of the column. In the sacral region
the fibres arise from the deep surface of the tendinous origin of the erector
spinae, from the groove on the back of the sacrum as low as the fourth fora-
men, from the inner part of the posterior extremity of the iliac crest, and
from the ligaments between that bone and the sacrum ; in the lumbar
region they take origin from the mammillary processes ; in the dorsal
region from the transverse processes ; and in the neck from the articular
processes of the four lower cervical veitebrse. From these several points
the muscular bundles ascend obliquely, to be inserted into the laminae of the
vertebrae, and into the spines from their bases nearly to their extremities.
The fibres from each point of origin are fixed to several vertebrae, some
being inserted into the side of the spinous process next above, and others
ascending more and more vertically as high as the fourth from the place of
origin ; the longer fibres from one origin overlapping those from the origin
next above.
The rotatores spince are eleven pairs of small muscles, which may be
regarded as the deepest fibres of the multifidus spinse in the dorsal region,
and are distinguished by being more nearly horizontal than the rest. Each
arises from the upper and back part of the transverse process, and is inserted
into the vertebra next above, at the inferior margin and on part of the
surface of the lamina, as far as the root of the spinous process.
INTERTRANSVERSALES. The intertransversales are short muscles passing
nearly vertically from vertebra to vertebra between the transverse processes.
They are most developed in the cervical, and least in the dorsal region.
Beneath each cervical transverse process there are two such muscles, one
descending from the anterior, and another from the posterior part of the
process. In the lumbar region there are likewise two sets : one set, the
intertransversales laterales, lie between the transverse processes, and are in
series with the levatores costarum ; the other set, intertransversales mediates
or interaccessorii, pass from the accessory process of one vertebra to the
mammillary process of the next, and are in series with the intertransversales
of the dorsal region.
INTERSPINALES. The interspinales are short vertical fasciculi of fleshy
fibres, placed in pairs between the spinous processes of the contiguous verte-
brae. They are best marked in the neck, where they are connected one to
each of the two parts into which the spinous process is divided. In the dorsal
part of the column only a few are met with, and these are not constant.
The spinalis cervicis consists of a few irregular bundles of fibres, of greater length
than the preceding muscles, placed close to the ligamentum nuchee : they arise by
two or more heads from the spines of the fifth and sixth cervical and sometimes other
neighbouring vertebrae, and are inserted into the spine of the axis, and occasionally
into the two vertebrae next below it. This muscle is sometimes wanting. (See
Henle and Heilenbeck, in " MUller's Archiv," 1837.)
The name sacro-coccygcus posticus, or extensor coccygis, has been given to slender
fibres occasionally found extending from the lower end of the sacrum to the coccyx,
SHORT POSTERIOR CRAXIO-VERTEBRAL MUSCLES.
239
and representing the extensor of the caudal vertebrae of other animals. (Giinther and
Milde, " Chirurglsche Muskellehre," quoted in Theile; " Sommerring von Baue,"
&3.)
SHORT POSTERIOR CRANIO- VERTEBRAL MUSCLES. The rectus capitis posticus
major arises by a narrow tendon from the spinous process of the axis, and
expanding as it passes upwards and outwards, is inserted into and beneath, the
outer part of the inferior curved line of the occipital bone. Its insertion is
inside and below that of the superior oblique muscle.
Fig. 192.
Fig. 192. VIEW OP THE DEEP POS-
TERIOR MUSCLES OP THE UPPER PART
OP THE VERTEBRAL COLUMN. ^
a, posterior occipital protuberance ; 6,
surface between the superior and in-
ferior curved lines on which the corn-
plexus is inserted ; c, spinous process of
the axis vertebra; d, transverse pro-
cess of the atlas ; e, transverse process
of the first dorsal vertebra; /, lamina of
the sixth dorsal vertebra ; 1, rectus
capitis posticus minor muscle; 2, rectus
posticus major ; 3, obliquus superior ;
4, obliquus inferior ; 5, rectus capitis
lateralis ; 6, trachelo-raastoid, the mus-
cle of the right side turned inwards and
its slips of attachment to the dorsal and
cervical transverse processes separated
from each other ; 7, transversalis cer-
vieis, the figures are placed near the
extreme ends of the muscle on the right
side ; 7', on the left side, upper part
of the longissimus dorsi continued into
the transversalis cervicis; 8, ascendens
cervicis, the muscle of the right side is
spread out ; 8', on the left side, the
seven upper tendinous insertions of the
ilio-costalis and accessorius muscles ; 9,
upper part of the semispinalis colli of the
left side ; 10, placed on the seventh rib
of the right side, close to the insertion of
its levator costa3 muscle ; 11, 11, three
rotatores vertebrarum between the third
and sixth dorsal vertebrae.
The rectus capitis posticus minor
arises from the posterior arch of
the atlas by the side of the
tubercle, and expands as it passes
to be inserted into the inferior
curved line of the occipital bone,
and the rough surface between
that and the foramen magnum.
The obliquus capitis inferior, the strongest of the muscles now under
consideration, arises from the spinous process of the axis, between the origin
of the rectus posticus major and the insertion of the semispinalis colli, and
is inserted into the extremity of the transverse process of the atlas.
The obliquus capitis superior, smaller than the preceding muscle, arises
from the upper surface of the transverse process of the atlas, inclines from
240 DORSAL MUSCLES OF THE TEUNK.
thence obliquely upwards and backwards, increasing somewhat as it ascends,
and is inserted into a groove situated externally to the inferior curved line
of the occipital bone.
The two oblique muscles, with the rectus major, form the sides of a small triangular
space, in the area of which the posterior primary branch of the sub-occipital nerve
and the vertebral artery will be found.
ACTIONS. The transverso-spinales muscles, including the complexus, are essentially
extensors of the head and vertebral column ; and the movements produced by them
vary according as the muscles of one side or both are in action, in a manner similar
to that already pointed out in regard to the erector muscles.
The interspinales and intertransversales muscles approximate the vertebras between
which they pass, and thus may act as extensors and lateral flexors respectively of the
portion of the vertebral column in which they are situated.
Of the four muscles last described, two the rectus minor and superior oblique
act principally by drawing the head backwards, that being the chief movement
allowed between the atlas and occipital bone ; while the principal action of the rectus
posticus major and the inferior oblique, when acting on one side, is to rotate the atla.s
and skull upon the axis.
DORSAL AND LUMBAR FASCIA. Under the name of lumbar fascia or
aponeurosis it has been customary to describe three layers of strong fibrous
substance sheathing the erector spinse and quadratus lumboruni muscles.
The deeper parts of this structure, to which by some the name of lumbar
fascia is restricted, will be described along with the abdominal muscles, with
which they are chiefly connected. The superficial or posterior layer is that
through which the latissimus dorsi and serratus posticus inferior are attached
to the spines of the dorsal, lumbar and sacral vertebrae and to the crest of
the ilium. This layer, which is of considerable strength, extends outwards
beyond the origin of the latissimus and serratus inferior, and being closely
united with the middle layer, binds down firmly the erectores spinse
muscles : it is by some described as the lower part of the vertebral aponeu-
rosis, with which it is continuous, by others it has been named the
aponeurosis of the latissimus dorsi.
The vertebral aponeurosis, strictly so called, is situated on the same plane
as the serratus posticus inferior, and consists of a thin lamella which sepa-
rates the muscles belonging to the shoulder and arm from those which
support the spine and head. Its fibres are for the most part transverse ;
some however are longitudinal. Above, it passes beneath the superior
serratus ; below, it is connected with the tendons of the latissimus and
inferior serratus muscles, and in being stretched from the spinous processes
outwards across the vertebral groove, it helps to enclose the angular canal in
which are lodged the long extensor muscles.
MUSCLES OP THE THORAX.
The muscles of the thoracic wall are the intercostales, levatores costarum,
subcostales and triangularis sterni, and along with these the diaphragm inter-
vening between the thorax and abdomen may conveniently be grouped.
The intercostal muscles consist of two thin layers of oblique short muscular
fibres filling up the inter-costal spaces : these layers are named respectively
the external and internal muscles.
The external intercostal muscles are formed of muscular fibres, with some
tendinous fibres intermixed, directed obliquely downwards and forwards
from one rib to another. Their extent for the most part is from the
INTERCOSTAL MUSCLES.
241
tubercles of the rib, nearly to the outer end of the cartilages ; but
in the two lowest ' intervals they reach forwards to the ends of the spaces.
Thin tendinous fibres, having the same direction as the external intercostal
muscles, are continued forwards between the costal cartilages from the points
where the muscles cease to the sternum, and there cover the internal
intercostals.
Fig. 193.
Fig. 193. VlEW OF SEVERAL OF THE MlRDLE DORSAL VERTEBRA AND RlBS, TO SHOW
THE INTERCOSTAL MUSCLES (after Cloquet). ^
A, from the side ; B, from behind.
IV, the fourth dorsal vertebra ; V, V, the fifth rib and its cartilage ; 1, 1, the levatorea
costarum muscles, short and long ; 2, the external intercostal muscles in the upper of the
two intercostal spaces represented ; 3, the internal intercostal layer shown in the lower
of the two spaces represented by the removal of the external layer, and seen in A in the
upper space, where the external layer terminates in front : the deficiency of the internal
layer towards the vertebral column is shown in B.
The internal intercostal muscles, placed deeper than the preceding,
are attached to the inner margins of the ribs and their cartilages. Com-
mencing at the anterior extremities of the cartilages of the ribs, they extend
as far back as a point within the angles of those bones. The fibres incline
downwards and backwards, crossing those of the external intercostals ;
they are, however, somewhat shorter and less oblique in their direction.
The internal are separated from the external intercostal muscles at the back of the
spaces by the intercostal vessels and nerves ; they are lined internally by the pleura.
The levatores costarum y twelve on each side, arise from the tips of the
transverse processes of the seventh cervical and eleven highest dorsal ver-
tebrae. Corresponding in direction with the external intercostal muscles, on
which they lie, they pass downwards and outwards, spreading as they
242
MUSCLES OF THE THORAX.
descend, and each is inserted into the outer surface of the rib belonging
to the vertebra below that from which it springs. The levator muscles
belonging to the lower ribs present some longer additional fibres which,
passing over one rib, are inserted into the next one below ; these fibres are
sometimes distinguished as levatores loj^giores costarum.
The levatores costarum lie in. series superiorly with the scaleni medius and pos-
ticus, and inferiorly with the external range of lumbar intertransverse muscles.
Fig. 194.
Fig. 194. VIEW OF THE DEEP MUSCLES OP THE ANTERIOR WALL OP THE THORAX, SEEN
FROM BEHIND (modified from Luschka). j
a, back of the manubrium of the sternum ; &, clavicles ; I to XI, the anterior parts
of eleven ribs and costal cartilages ; 1, 1', sterno- thyroid muscle, that of the right side
being cut short to show more fully the next mnscle ; 2, 2', the sterno-hyoid ; 3, trian-
gularis sterni ; 4, upper part of transversalis abdominis united in 4', 4', the back of the
linea alba ; 5, attachments of the diaphragm to the lower ribs (the twelfth not represented
in the figure), indigitating with those of the transversalis ; 5', the two slips to the ensi-
form process ; 6, internal layer of intercostal muscles extending to the sternum, shown
in all the spaces on the right side, but only in the two uppermost of the left side ; 7, in
the lower spaces of the left side, indicates the external layer of intercostal muscles
exposed by removing the internal layer.
TRIANGULARIS STERNI. DIAPHRAGM. 243
The subcostal or infracostal muscles are small bundles lying on the inner
aspect of the thoracic wall, close to the surface of the internal iuter-
costals, and chiefly in the neighbourhood of the angles of the ribs. They
follow the same direction as the internal iutercostal muscles, but their fibres
extend over two or three iutercostal spaces. They are most constant on
the lower ribs (see fig. 195.)
The it iauyularis sternly a thin stratum of muscular and tendinous fibres
placed within the thorax, behind the costal cartilages, arises from the deep
surface of the ensiform process of the lower part of the body of the
sternum, and of the cartilages of one or two of the lower true ribs. Its
fibres pass outward and upwards in a diverging manner, the lowest being
horizontal, the middle oblique, and the upper becoming more and more
nearly vertical ; and are inserted by separate slips into the cartilages of the
true ribs from the sixth to the second inclusive, on the lower border and
inner surface of each, at the junction with the bony part. At the lower
margin the fibres are in the same plane with those of the transversalis
abdoininis, of which this muscle is a continuation upwards.
The triangularis sterni is subject to much variation as to its extent and points of
attachment in different bodies, and even on the opposite sides of the same body.
The internal mammary artery and veins pass between its anterior surface and the
costal cartilages.
Occasional Muscle. The rectus sternalis, or sternalis brutorwm, is an elongated
muscle, of nearly the same length as the sternum, frequently seen lying in front and
parallel to the outer margin of that bone, and over the inner part of the pectoral muscle.
It is fleshy in the middle and tendinous at both ends it is attached superiorly to the
sternum in connection with the tendon of the sterno-mastoid, and inferiorly it is
connected with the rectus abdominis muscle. It is rarely present on both sides. It
represents a muscle which is constant in some animals.
THE DIAPHRAGM.
The diaphragm, phren, septum transversum, or midriff, forms a musculo-
tendinous partition between the abdominal and thoracic cavities. It
consists of muscular fibres which arch upwards as they converge from the
circumference of the visceral cavity to a tendinous structure in the centre,
and it is perforated by the various structures which pass from the thorax to
the abdomen.
The fibres arise from the bodies of several of the upper lumbar vertebrae
by two thick crura ; from two arches on each side external to the bodies of
the vertebras, called ligarnenta arcuata ; and from the ensiform cartilage
and the cartilages of the six lower ribs.
a. The crura arise by tendinous fibres more or less distinctly aggregated
into two bundles which are attached over a varying extent of surface. On
the right side they are connected with the first, second, and third lumbar
vertebrae, and the interposed fibro- cartilages, or sometimes with the second,
third, and fourth ; on the left side, the attachment is shorter by the breadth
of one vertebra. The tendons of both crura curve forwards and upwards
so as to enclose the aorta in an arch between them and the bodies of the
vertebras ; their inner margins are united behind, so that they form a
nearly complete fibrous ring round that vessel. The muscular fibres of the
crura, springing from those tendons in thick bundles, on each side of
the aorta, diverge as they pass upwards to the central aponeurosis. The
innermost fibres on each side decussate with those of the side opposite, those
244
MUSCLES OF THE THORAX.
of the right usually lying anterior to those of the left, and, curving upwards,
limit an opening for the transmission of the oesophagus, before ending in
the central aponeurosis.
-g- Fig. 195. THE LOWER HALF OF
=>' THE THORAX, WITH FOUR LUM-
BAR VERTEBRAE, OPENED so AS
TO SHOW THE DIAPHRAGM
FROM BEFORE (modified from
Luschka).
a, sixth dorsal vertebra ; b,
fourth lumbar vertebra ; c, ensi-
form process of the sternum ; d,
the aorta descending in front of
the lower dorsal vertebras ; d', the
aorta emerging in the abdomen
below the arch formed by the
meeting of the pillars of the dia-
phragm ; e, the oesophagus de-
scending through its aperture in
the diaphragm ; /, opening in the
tendon of the diaphragm for the
inferior vena cava ; 1, central, 2,
right, and 3, left division of the
trefoil tendon of the diaphragm ;
4, right, and 5, left muscular part,
descending from the margins of the
tendon to be attached to the ribs ;
6, the right, and 7, the left crus
or pillar of the muscle ; 8, to 8',
in the three upper intercostal spaces
of the right side the internal
layer of intercostal muscles inter-
rupted towards the vertebral co-
lumn, where in the two upper
spaces the external layer, 9, 9, is
seen ; in the lowest space shown
the external layer is not represented ; 10, 10, on the left side, indicate the form and
position of a part of the subcostal or innermost layer of intercostal muscles.
6. The lie/amentum arcuatum internum is a fibrous band which extends
from the body to the transverse process of the first lumbar vertebra, and
sometimes also to that of the second, and arches over the upper part of
the psoas muscle. The ligamentum arcuatum externum extends outwards
from the transverse process of the first lumbar vertebra to the last rib,
arching over the front of the quadratus lumborum : it is the upper part of
the fascia covering that muscle, somewhat increased in thickness. From
both ligamenta arcnata diaphragmatic muscular fibres take their origin, and
are directed upwards to the posterior part of the tendinous centre.
c. The fibres arising from the cartilages of the six lower ribs form a series
of serrated slips interdigitating with the attachments of the transversalis
abdomiuis muscle. They sometimes arise also in part from the osseous
ribs. The fibres proceeding from the eusiform cartilage form a narrow slip,
sometimes divided, on each side of which there occurs an interval, in
which the lining membranes of the thorax and abdomen are separated
only by a small quantity of loose connective tissue. The anterior fibres of
the diaphragm are much the shortest. The fibres of the sternal and costal
slips, after being united into the general plane of the muscle, rise in an
THE DIAPHRAGM.
245
Fig. 196.
arched and converging manner to be inserted into the anterior and external
margins of the central tendon.
d. The central tendon trefoil or cordiform tendon, or phrenic centre,
is a strong aponeurosis, forming the central and highest part of the
diaphragm. It is elongated from side to side, and consists of three lobes or
alee, partly separated by indentations. The right lobe is the largest ; and
the left, which is elongated and narrow, is the smallest of the three. The
central tendon is surrounded on every side by the muscular portion of the
diaphragm, the fibres of which are directly continuous with those of the
tendon. The tendinous fibres cross one another, and are interwoven in
various directions.
Fig. 196. VIEW OP THE
DIAPHRAGM, FKOM BE-
LOW. I
In the preparation from
which this figure is drawn,
the lower ribs and sternum
are thrown upwards so as
to expose and stretch the
lower surface of the dia-
phragm, and the four
tipper lumbar vertebrae
have been exposed by the
removal of all the muscles
on the right side, and the
dissection of the psoas mag-
nus and quadratus lumbo-
rum on the left side, a,
the aorta emerging in the
abdomen below the ten-
dinous arch formed by the
union of the pillars of the
diaphragm on the first
lumbar vertebra ; b, the
oesophagus seen entering
the abdomen through the
aperture in the united
muscular crura (this aper-
ture should have been
represented a little to the
left of the middle line) ;
c, the aperture for the
vena cava inferior situated
at the place of union of
the middle and right divi-
sions of the trefoil tendon ; d, the body of the fourth lumbar vertebra ; e, e, the twelfth
ribs near their extremities ; /, /, the ends of the eleventh ribs ; 1, the tendinous part
of the right crus ; 2, the left ; 3, the tendinous arch formed by their union over the
aorta, above which the decussation of muscular fibres is seen ; 4, second decussation of
muscular fibres in front of the cesophageal opening ; 5, on the right side, placed near the
end of the transverse process of the first lumbar vertebra, towards which, arching from
above and from within, over the + , is seen the ligamentum arcuatum internum ; and
from which, passing towards e, is seen the ligamentum arcuatum externum ; 5', on the
left side, is in a similar position, but here the quadratus lumborum muscle is seen
descending from the twelfth rib behind the ligamentum arcuatum externum, and the
tipper part of the psoas muscle is within the ligamentum arcuatum internum ; 6, the middle
division of the trefoil tendon, from which in front pass the slips of attachment of the
diaphragm to the ensiform process ; 7, the left, and 8, the right divisions of the trefoil
tendon ; from the outer and anterior margins of these the costal slips of the muscle are
seen diverging, and from the posterior border of the tendon the slips of origin proceeding
from the ligarnenta arcnata and the tendinous arch of the crura ; 9, part of the quadratus
lumborum ; 10, part of the psoas magnus.
246 MUSCLES OF THE THORAX.
Foramina. There are in the diaphragm three large perforations for the
passage respectively of the aorta, the oesophagus, and the vena cava, besides
some smaller holes or fissures which are less regular. a. The foramen
for the aorta (hiatus aorticus), placed in front of the vertebrae, is bounded
by tendinous fibres of the crura as already described. Besides the aorta,
this opening transmits the thoracic duct, and generally also the vena
azygos. b. The foramen for the oesophagus, higher and farther forward
than the preceding, as well as a little to its left, is separated from that
opening by the decussating fibres of the crura. It is oval in form, and is
generally entirely surrounded by muscular fibres ; in some rare cases,
however, a small part, the anterior margin, is found to be tendinous, being
formed by the margin of the central tendon. c. The opening for the vena
cava (foramen quadratam) is placed in the highest part of the diaphragm,
in the tendinous centre at the junction of the right and middle alee,
posteriorly. Its form is somewhat quadrangular ; and it is bounded by
fasciculi of tendinous fibres running parallel with its sides.
Besides the foregoing large foramina, there are small perforations through the crura
for the sympathetic and splanchnic nerves on both sides, and for the vena azygos minor
on the left side. Moreover, the larger azygos vein often takes its course through the
right crus.
The upper or thoracic surface of the diaphragm is highly arched. Its posterior and
lateral fibres, ascending from their connection with the lower margin of the thorax,
are for a considerable extent placed close to the ribs, the lungs not descending so far
as their attachments. The vault of the diaphragm rises higher on the right than on
the left side. On the right side in the dead body it rises to the level of the fifth rib
at the sternum, and on the left side only as high as the sixth. This difference has
relation to the great size and firmness of the liver on the right side. It is covered
superiorly by the pleura and the pericardium ; the fibrous layer of the latter mem-
brane blending with the tendinous centre, as well as with the fascia covering its
muscular substance. The lower surface, of a deeply concave form, is lined by the
peritoneum, and has in apposition with it the liver, the stomach, the pancreas and
spleen, and the kidneys.
ACTIONS MOVEMENTS OP RESPIRATION. The mechanical act of respiration consists
of two sets of movements, viz., those of inspiration and of expiration, in which air
is successively drawn into the lungs and expelled from them by the alternate
increase and diminution of the thoracic cavity. The changes in the capacity of the
thorax are effected by the expansion and contraction of its lateral walls, called costal
respiration, and by the depression and elevation of the floor of the cavity, through
contraction and relaxation of the diaphragm, called abdominal respiration. These
two methods of respiration are normally combined, but in different circumstances
one method is resorted to more than another. Thus, abdominal respiration is most
employed in the male, costal respiration most in the female.
Inspiration. The study of the movements of the thoracic walls in respiration
presents the difficulty that those movements cannot be perfectly imitated on the pre-
pared skeleton, because the force cannot on it be applied between one rib and another
as during life, and because the resistance to expansion is no longer of the same
description. On the prepared skeleton, by raising and depressing the sternum the
ribs may be moved upwards and downwards, parallel to one another ; the first rib
moving as freely as the others. But during life several causes combine to make the
first rib more fixed than those which follow : as for example, the weight of the upper
extremity, and the strain of the intercostal muscles and ribs beneath. The move-
ments of the thoracic walls in respiration are these. 1st. The antero-posterior dia-
meter is increased by a forward movement of the sternum ; the lower end of that
bone is raised and advanced, while the upper end, which in easy respiration is at rest,
or nearly so, is only raised in full inspiration. 2nd. The lateral diameter of the
thorax is increased, both by the elevation and the rotation of the ribs ; the first of
these movements bringing larger costal arches to a level occupied in expiration by
MECHANISM OF THE RESPIRATORY MOVEMENTS. 247
smaller arches above them ; and the second, by the movement or rotation of the ribs
round an axis extending from their heads to the sternum, which everts the lower edge
of the ribs, and increases the width of their arch outwards. 3rd. The capacity of the
thorax, transversely and posteriorly, is increased by the elastic bending of the ribs, as
well as the opening of the angle between the ribs and their cartilages, produced by the
resistance of the sternum and weight of the limbs to the forward and upward motion
of the extremities of the cartilages, and by the inclination backwards given to the
middle ribs in their upward movement by the oblique direction of the plane of the
costo-transverse articular surfaces. It is further to be noticed, that any considerable
elevation of the lowest ribs, instead of increasing, would diminish the capacity of the
thorax by raising the diaphragm, and accordingly in inspiration those ribs are drawn
backwards and outwards rather than raised. Lastly, it may be remarked, that
extension of the vertebral column is an important agent in respiration, for when the
column is bent forwards, the ribs are pressed together in the concavity of the curve,
and, conversely, when the column is extended the ribs are separated.
The Intercostal Muscles. The manner in which these muscles act has been a sub-
ject of controversy from an early time, and cannot be said to be yet thoroughly
understood. Among those who look upon the intercostal muscles as active in
respiration, all are agreed that the external muscles are elevators of the ribs, and
therefore muscles of inspiration. According to one view, defended by Haller, the
external and internal layers have a common action, the decussating fibres acting in
the direction of the diagonal between them ; while according to another view, that of
Hamberger, while the external intercostal muscles are admitted to be elevators, the
internal are held to be depressors of the ribs. A more recent modification of these
views, which is at present most generally adopted, is that maintained by Hutchinson,
viz., that the external intercostal muscles, and the parts of the internal intercostals
placed between the costal cartilages, elevate the ribs, and that the lateral portions of
the internal intercostals act as depressors. This view is founded upon a mathematical
demonstration, and may be illustrated mechanically by an apparatus showing that if
two parallel bars, free at one end and attached by joints to a fixed perpendicular at
the other, be united by oblique elastic bands, one set of which is directed downwards
and away from the fixed upright, while another is directed downwards and towards
the upright, the first set of bands will be shortened by the elevation of the bars
from an oblique to a horizontal position, and the second set lengthened ; whereas
the first set will be lengthened and the second shortened by depression of the bars
below the horizontal position. It may be objected, however, to this vieT, that
the ribs differ from the supposed bars in respect that they are not rigid, and are not
free at either end, but have the greatest extent of motion, at least in some instances,
in the middle of their arch, and in the living subject, the ribs, in their elevation, both
rotate upon their axis and bend upon themselves, instead of describing a simple
upward and downward movement like the bars. The deficiency of the external inter-
costal muscles in front and of the internal behind, in which situations they would
have acted as depressors, seems to point to some sort of combined action of the
muscles as elevators of the ribs.
Among the more recent anatomical writers, Henle inclines to Haller's view;
Luschka refers to Budge's experiments on the muscles of living animals, as proving
that the internal intercostal muscles elevate the ribs (Budge, "Lehrbuch der Phy-
siologic des Menschen," Weimar, 1860, p. 79) ; and Cruveilhier, founding on the
experiments of Beau and Massiat, supports the very different but scarcely tenable
view, that the intercostal muscles are not essential agents either in elevating or
depressing the ribs, but only act as tensors of the intercostal spaces (op. cit. p. 575).
The levatores costarum have a similar action with the posterior fibres of the
external intercostal muscles, and ought therefore to be ranked among the agents of
inspiration. The scalene muscles also are usually believed to contribute, even in
normal and quiet inspiration, to the support and elevation of the first and second
ribs ; and it is obvious that the serratus posticus superior must have a similar effect
on those upper ribs to which it is attached.
The action of the diaphragm is more easily understood than that of the intercostal
muscles. By its contraction and descent its convexity is diminished, the abdominal
viscera are pressed downwards, and the thorax expanded vertically. The fibres
248 MUSCLES OF THE ABDOMEN.
arising from the lowest ribs, being directed nearly vertically upwards from their costal
attachments, must tend to pull those ribs upwards. The serratus posticus inferior
and quadratus lumborum muscles, by opposing the diaphragm, and thus giving it a
fixed point on which to descend, become assistant muscles of inspiration. The ante-
rior fibres of the diaphragm being directed more horizontally towards the central
tendon, oppose the forward motion of the sternum : hence the sternum becomes
arched in patients long subject to asthma. (Hutchinson, Article " Thorax," in Todd's
" Cyclopaedia of Anatomy and Physiology ; " Meyer, " Physiologische Anatomic.")
In more forcible inspiration, and more especially in severe attacks of dyspnoea,
there are called into play other powerful muscles, to secure the inspiratory action of
which a fixed attachment must be provided by the support and elevation of the
shoulder and arm ; among these may be enumerated the serratus magnus and pec-
toralis minor, acting from the shoulder, and the pectoralis major and latissimus dorsi,
acting from the raised arm, which together produce expansion and elevation of the
ribs.
Expiration. In normal and quiet expiration the diminution of the capacity of the
chest is mainly, if not wholly, due to the return of the walls of the chest to the condi-
tion of rest, in consequence of their own elastic re-action, and of the elasticity and weight
of the viscera and other parts displaced by inspiration ; the lungs themselves, after
distension by air, exert considerable elastic force, and no doubt the ribs and their
cartilages re-act strongly by their elastic return from the elevated and bent condition
into which they had been thrown by the inspiratory forces. In more forcible acts of
expiration, in muscular efforts of the limbs and trunk, and in efforts of expulsion
from the thoracic and abdominal cavities, all the muscles which tend to depress the
ribs, and those which compress the abdominal cavity, concur in powerful action to
empty the lungs, to fix the trunk, and to expel the contents of the abdominal viscera.
(See further " Action of the Abdominal Muscles.")
MUSCLES OF THE ABDOMEN.
The muscular wall of the abdomen is formed, in great part of its extent
on each side, of three layers of muscle, the fibres of which run in different
directions ; those of the two most superficial layers lying obliquely, and
those of the innermost layer being transverse. In front those three layers
of muscle are absent, and are replaced by tendinous expansions, which meet
in the middle line, and on either side of that line the fibres of the recti
muscles extend in a vertical direction between the tendinous layers, sup-
ported usually at the lower end by the pyramidales muscles. Posteriorly
the wall is formed in part by aponeurosia, and in part by muscles of which
the fibres are chiefly vertical, viz., the muscles of the back, and in front of
them the quadratus lumborum.
The superficial or external oblique muscle (descending or gieat oblique)
arises from the outer surface of the eight inferior ribs, by slips arranged in
a serrated series, four or five of them meeting with origins of the serratus
magnus, and three or four with origins of the latissimus dorsi. The slips of
these two sets of muscles alternate with each other, as the tips of the fingers
of one hand may be made to fit in between those of the other, and hence
they are said to interdigitate, and are termed digitations. The lower and
the upper digitations of the external oblique are connected with the ribs near
their cartilages, the others are attached to the ribs at some distance from
their extremities ; the lowest digitation generally embraces the point of the
twelfth rib. The fleshy fibres from the last ribs pass down in nearly a
vertical direction to be inserted into the external margin of the crest of the
ilium for about the anterior half of its length ; all the rest incline down-
wards and forwards, and terminate in tendinous fibres, which form the
broad aponeurosis by which the muscle is inserted.
EXTERNAL OBLIQUE MUSCLE.
249
The aponeurosis of the external oblique, wider at the lower than at the
11 nper part, and larger than that of either of the subj acent abdominal muscles,
extends inwards towards the middle line in front ; at some distance from
this, but farther out above than below, it becomes inseparably united with
the aponeurosis beneath, and forms a part of the sheath of the rectus
muscle in the whole extent of the space from the ensiform cartilage to the
symphysis pubis. The upper part of the aponeurosis is connected externally
with the larger pectoral muscle. Its lower fibres are closely aggregated
together, and extend across from the anterior superior iliac spine to the
spine of the pubes, in the form of a broad band, which is called the liga-
ment of Jfallopius, or more commonly of Poupart. This band is curved at
the middle and outer parts, the convexity of the curve being directed towards
Fig. 197.
Fig. 197. SUPERFICIAL VIEW OF THE MUSCLES OF THE ABDOMEN, PROM BEFORE.
14, external oblique muscle ; 15, is placed on the ensiform cartilage at the upper end
of the linea alba ; 15', umbilicus ; 16, syraphysis pubis at the lower end of the linea
alba ; above 16, the pyramidales muscles are seen shining through the abdominal
aponeurosis ; from 14 to 17, the linea semilunaris ; between this line and the linea alba
are seen the transverse lines of the rectus muscle ; above 22, the curved margin of
Poupart's ligament; on either side of 16, the external abdominal ring is indicated.
250 MUSCLES OF THE ABDOMEN.
the thigh, a form which is given to it by its connection with the fascia lata
of the limb.
Above the crest of the pubes the fibres of the aponeurosis, separating from
the inner part of Poupart's ligament, leave between them an oblique open-
ing, the superficial or external abdominal ring, through which passes the
spermatic cord in the male, and the round ligament in the female. The
direction of this opening is upwards and outwards, its base being formed by
the pubic crest, and its sides by the two sets of diverging fibres called the
pillars. The upper or internal pillar is attached to the anterior surface of
the symphysis pubis, interlacing with the corresponding fibres of the opposite
side ; the lower or external pillar is formed by Poupart's ligament, near its
attachment to the spine of the pubic bone.
A portion of the aponeurosis, which is reflected backwards and outwards
along the pectineal line from the attachment of Poupart's ligament to the
spine of the pubes, constitutes a small triangular process with a curved
external border, not far distant from the femoral ring. This receives the
name of Gimbernafs ligament. Some curved fibres, directed across the
diverging pillars and uniting them together, are named intercolumnar. A
few of these, descending upon the spermatic cord from the margin of the
opening, are prolonged upon that structure as a delicate fascia, named
intercolumnar fascia. The intercolumnar fibres may be regarded as the
lowest of a series of tendinous fibres, which cross the aponeurosis of the
external oblique muscle somewhat obliquely over a considerable extent of its
surface, and the strongest of which proceed from near the superior spine of
the ilium and upper part of Poupart's ligament.
The deep or internal oblique muscle (ascending or small oblique), placed
under cover of the external oblique, arises by fleshy fibres from the external
half or two-thirds of the deep surface of Poupart's ligament, from the iliac
crest for two-thirds of its length, and by some fibres from the posterior
aponeurosis of the transversalis muscle, in the angle between the crest of
the ilium and the outer margin of the erector spinae muscle. From those
attachments the fibres, spreading somewhat, pass to be inserted as follows :
the most posterior fibres pass upwards and forwards to the lower margins of
the cartilages of the last four ribs, where they are inserted in the same plane
with the internal intercostal muscles ; those arising further forwards from
the crest of the ilium pass, the upper more obliquely, and the rest more
horizontally, forwards to end in an aponeurosis in front of the abdomen ;
those from the front part of the crest extend horizontally inwards to the
same aponeurosis ; while the fibres from Poupart's ligament, usually paler
than the rest, arch downwards and inwards over the spermatic cord, or the
round ligament of the uterus, and end in tendinous fibres common to them
and the lower part of the transversalis muscle, and hence known as the
conjoined tendon of these muscles ; through the medium of this tendon they
are attached to the front of the pubes, and for some distance along the
pectineal line, behind and to the outside of Gimbernat's ligament. The
spermatic cord and round ligament pass under the arched lower border of
the internal oblique and transversalis muscles through the internal or deep
abdominal ring.
The aponeurosis may be regarded as the expanded tendon of the muscle
continued inwards in front ; it extends from the margin of the thorax to
the pubes, and is wider at the upper than at the lower end. At the outer
border of the rectus muscle this structure divides into two layers, one
passing before, the other behind, that muscle ; and the two reunite at its
INTERNAL OBLIQUE MUSCLE.
251
inner border, so as to enclose it in a sheath. The anterior layer, as already
mentioned, becomes inseparably united with the aponeurosis of the external
oblique muscle, and the posterior layer is similarly incorporated with that
of the transversalis. The upper border of the posterior lamina is attached
to the margins of the seventh and eighth ribs, as well as to the ensiform
cartilage. This division, however, of the aponeurosis into layers stops
short a little above the middle distance between the umbilicus and the
pubes, the aponeurosis below that level remaining undivided, and along with
Fig. 198.
Fig. 198. LATERAL VIEW OF THE
MUSCLES OP THE ABDOMEN AND
TRUNK, THE INTERNAL OBLIQUE
MUSCLE HAVING BEEN EXPOSED
BY THE REMOVAL OP THE EXTERNAL
OBLIQUE (modified from Henle).
a, anterior superior spinous process
of the ilium ; 6, trochanter major ;
c, spine of pubes ; d, lumbar fascia ;
VI to XII, the sixth to tbe twelfth
ribs ; 1, lower part of the great pec-
toral muscle, where it is attached to
the external oblique muscle ; 2, 2,
lower digitations of the serratus mag-
nus from the fourth to the eighth ribs ;
3, lower costal attachments of the
latissimus dorsi ; 3', its iliac attach-
ment ; 4, trapezius ; 5, divided attach-
ments of the external oblique, left in
connection with the ribs ; 5', aponeu-
rosis of tbe external oblique divided in
front of the rectus, where it joins the
sheath ; 6, internal oblique at its
middle ; 6', 6', line where it divides
to form the sheath of the rectos ;
+ + + XII, its attachments to the
four lowest ribs ; 6", the conjoined
tendon, and above, and to the out-
side, the internal inguinal aperture ;
7, sartorius ; 8, rectus femoris ; 9,
tensor vaginae femoris ; 10, gluteus
medius ; 11, gluteus maximus.
that of the transversalis muscle to
which it is united, passing wholly
in front of the rectus muscle. The
deficiency thus resulting in the
posterior wall of the sheath of
the rectus muscle is marked
superiorly by a well-defined lu-
nated edge, whose concavity
looks downwards towards the
pubes the semilunar fold of
Douglas.
The internal oblique muscle is
almost entirely covered by the ex-
ternal oblique. A small angular portion only near the place where its posterior fibres
take their origin, under cover of the latissimus dorsi, is exposed between that muscle
and the external oblique, and even this is not constantly found.
The cremaster, a muscle peculiar to the male, consists of fibres lying in
252
MUSCLES OF THE ABDOMEN.
series with those of the lower border of the internal oblique muscle. It
presents an external and an internal attachment. The external attachment
is to Poupart's ligament near its lower part, and there its fibres are continuous
with those of the internal oblique muscle ; the internal attachment, smaller
Fig, 199, Fig. 199. LATERAL VIEW
OP THE TRUNK, GIVING
A DEEP VIEW OF THE
SERRATUS MAGNUS AND
TRANSVERSALIS ABDO-
JJINIS MUSCLES. ^
The serratus magnus is
stretched out by the sca-
pula being drawn away
from the ribs, a, coracoid
process of the scapula ; b,
glenoid cavity ; c, lower
angle ; d, first dorsal ver-
tebra ; e, placed on the os
pubis, points to the inser-
tion of Gimbernat's liga-
ment ; I, VI, XII, the first,
sixth, and twelfth ribs ;
L', first lumbar vertebra ;
1, upper portion of the
serratus magnus attached
to the first and second
ribs ; 2, second or middle
portion attached to the
second and third ribs ; 3,
lower or fan- shaped portion
attached to the ribs from
the fourth to the ninth ;
4, the external intercostal
muscles ; 5, upper costal
origins of the transver-
salis abdominis ; 6, origins
of the muscle from the
transverse processes of the
lumbar vertebrae by the
lumbar aponeurosis ; 6',
part rising from the crest
of the ilium ; 7, lower
portion rising from the
upper half of Poupart's
ligament, and passing over
the internal inguinal aper-
ture ; 8, posterior layer of
the sheath of the rectus
muscle opened in its upper
part by removing the apon-
euroses of the oblique mus-
cles ; 9, the same in its
lower part left entire at the
place where the tendons
pass entirely in front of the
rectus muscle ; 10, the interspinales muscles of the lumbar vertebras ; 11, gluteus minimus;
12, pyriformis.
and less constant, is by means of a tendinous band to the spine and crest of
the pubes, close to the insertion of the internal oblique muscle. The
superior fibres of the muscle extend between those attachments in a series
TEAXSVERSALIS ABDOMIN1S MUSCLE. 253
of successively longer loops, descending in front of the spermatic cord, a
few of them reaching as low as the level of the testicle : the remaining
fibres, the greatest number of which descend from the outer attachment,
and a few from the inner, spread out inferiorly and are embedded in the
substance of a fascia, termed cremasteric, which adheres to the fascia propria
of the testicle. Sometimes the only fibres developed are a bundle descend-
ing from the outer attachment.
In the female there may be almost constantly detected a small bundle of fibres
descending on the round ligament of the uterus, which correspond with the last-
mentioned fibres of the cremaster muscle of the male.
The transversalis abdominis muscle, subjacent to the internal oblique,
arises from the inner surface of the cartilages of the six lower ribs j from a
strong aponeurosis attached to the lumbar vertebrse ; from the inner margin
of the crest of the ilium in the anterior two- thirds of its extent, and from
the iliac third of Poupart's ligament. The greater part of the fibres have
a horizontal direction, and extend forwards to a broad aponeurosis in front ;
the lowest fibres curve downwards like those of the internal oblique, and are
inserted into the front of the pubes and into the pectineal line, through the
medium of the conjoined tendon already described as common to this muscle
and the internal oblique.
The anterior aponeurosis of the transversalis muscle commences in the
greater part of its extent at the distance of about an inch from the outer
border of the rectus muscle ; but at its upper extremity this aponeurosis is
much narrower, and there the muscular fibres of opposite sides approach
nearly to the middle line behind the recti muscles. In the greater part of
its extent it becomes united with the posterior layer of the aponeurosis of
the internal oblique forming the rectus sheath, and inferiorly, where that
aponeurosis passes entirely in front of the rectus muscle, it remains blended
with it, and passes likewise in front of that muscle.
The posterior aponeurosis of the transversalis muscle extends backwards
between the last rib and the iliac crest, and opposite the outer border of
the erector spinse muscle, is continuous with the apoueurotic structure which
passes to the vertebral column in three layers, commonly named the pos-
terior, middle, and anterior layers of the lumbar aponeurosis. The posterior,
or most superficial, of these layers is that previously referred to as being
connected with the tendons of the latissimus dorsi and serratus inferior
muscles, and which is attached to the spinous processes of the vertebrae. The
middle layer, which is the strongest, is attached to the tips and margins of the
lumbar transverse processes, and lies between the erector spinse and quadratus
luxnborum muscles. The remaining deepest layer, comparatively thin, passes
in front of the quadratus lumborum muscle to the roots of the lumbar
transverse processes, and at its upper part, where it increases in thickness
and is connected with the last rib, it forms, as already mentioned, the
ligamentum arcuatum externuni of the diaphragm.
The triangularis sterni, when viewed from behind, along with the transversalis
abdominis, has the appearance of being a continuation of that muscle upon the
wall of the chest, above the diaphragm : hence the name of transversalis thoracis t
which has sometimes been given to it.
The rectus abdominis is a long Eat muscle, consisting of vertical fibres,
situated at the forepart of the abdomen, within a tendinous sheath formed
in the manner already described in the account of the aponeurosis of the
254
MUSCLES OF THE ABDOMEN.
internal oblique muscle ; it is separated from the muscle of the other side
by a narrow interval, which is occupied by a dense fibrous structure, the
linea alba afterwards described. It arises from the upper margin of the
pubes by a flat tendon consisting of two parts, of which the internal is much
Fig. 200.
Fig. 200. DEEP MUSCLES
OP THE FOREPART OF
THE TRUNK AND SHOUL-
DER.
The explanation of the
references from 1 to 11 has
already been given, in the
description of fig. 173.
, coracoid process ; &,
sternum ; c, c, cartilages
of the fifth ribs ; d, ensi-
form portion of the ster-
num ; e, symphysis pubis ;
/, anterior superior iliac
spine ; 12, on the fifth and
eighth ribs, near the in-
sertion of the serratus
magnus ; 13, on the right
side, the rectus abdominis
completely exposed ; on
the left side 13', 13', the
divided ends of the same
muscle, a portion being re-
moved ; 14, points to the
pyramidalis muscle exposed
on the left side ; 15, on
the right side, the internal
oblique muscle; 15', origin
of its lower fibres from the
deep surface of Poupart's
ligament ; 15", conjoined
tendon of the internal ob-
lique and transversalis, de-
scending to the pectineal
line ; between 15' and 15",
the internal or deep in-
guinal aperture.arched over
by the muscular fibres ; 15,
on the left side, cut edge
of the internal oblique,
shown diagrammatically,
to indicate the manner in
which its tendon splits to
form the sheath of the
rectus muscle ; 16, the
tendon or aponeurosis of
the external oblique muscle,
uniting in front with the
sheath of the rectus.
the smaller, and is con-
nected with the liga-
ments covering the
pubic symphysis, while the external one is fixed to the pubic crest.
Expanding and becoming thinner at the upper end, the muscle is inserted
into the cartilages of three ribs, the fifth, sixth, ani seventh, usually by
RECTUS MUSCLE. ABDOMINAL LINES. 255
three distinct parts of unequal size. Some fibres also are generally found
attached to the ensiform cartilage.
The fibres of the rectus muscle are interrupted by three or more irregular
tendinous intersections, named lince. trans versce. The three which are most
constant are placed, one opposite the umbilicus, another on a level with the
ensiform cartilage, and the third intermediately between them : and these
generally run across the whole muscle. When one or two additional trans-
verse lines occur, they are usually incomplete ; one of them is very gene-
rally placed below the umbilicus, the position of the other is variable. The
intersections do not usually penetrate the whole thickness of the muscle, but
are confined chiefly to its anterior fibres, and are firmly united to the anterior
wall of the sheath of the muscle, while the posterior surface of the muscle has
no attachment to the sheath.
The lineae transversse may be regarded as indications of the abdominal ribs of some
of the lower animals ; they sometimes extend outwards from the rectus, and penetrate
partially into the internal oblique.
The pyramidalis is a small muscle resting on the lower part of the rectus.
It arises from the front of the pubes and the ligaments of the symphysis
and becoming narrow as it ascends over the lower third of the interval
between the umbilicus and pubes, is inserted into the linea alba.
The pyramidalis is covered in front by the aponeurosis of the other muscles, and
rests posteriorly on the rectus, the size of the lower part of which is augmented when
the pyramidalis is wanting.
This muscle is often absent on one or both sides : in some instances it has been
found to be double. It occasionally exceeds the length above stated.
The linea alba is a white fibrous structure, extended perpendicularly
downwards in the middle line from the ensiform cartilage to the pubes. This
tendinous band is formed by the union of the aponeuroses of the two
oblique and the transverse muscles, the tendinous fibres being continued in
a decussating manner from one side to the other. Some longitudinal
fibres are distinguishable towards its lower end. It is broader superiorly
than inferiorly, and a little below the middle is widened out into a
circular flat space, in the centre of which is situated the cicatrix of the
umbilicus.
The linece semilunares are the two curved linear spaces on the surface of
the abdomen, placed externally to the outer margins of the recti muscles.
They are produced by the absence of muscular fibres behind that part of
the aponeurotic tendons ; they correspond on their inner side to the outer
margin of the sheath of the rectus, and on their outer side mainly to the
line of termination of the fibres of the oblique muscles in their aponeuroses.
The quadratus lumborum is an irregularly quadrilateral muscle, slightly
broader below than above, placed between the last rib and the crest of the
ilium, close to the vertebral column. It is divisible into two parts. One
of these, arising by fleshy and tendinous fibres from the ilio-lumbar ligament,
and from the iliac crest for several inches near the place where that ligament
is attached, is inserted into the inferior border of the last rib for about half
its length, and by four tendinous slips into the transverse processes of the
four superior lumbar vertebrae. Another series of fibres, arising by two or
three tendinous slips from as many of the inferior transverse processes at
their upper margins, passes in front of those inserted into the same processes,
and joins with the part of the muscle attached to the rib.
256
MUSCLES OF THE ABDOMEN.
The number of the points of insertion of this muscle to the vertebrae, and the
extent of its connection with the last rib, vary in different instances. It is sometimes
attached to the body or transverse process of the last dorsal vertebra.
This muscle is placed between the middle and deepest layer of the lumbar aponeu-
rosis, and its inner part is covered in front by the psoas muscle.
Fig. 201.
10*
Fig. 201. DIAGRAM OP A TRANSVERSE SECTION OP THE WALL OP THE ABDOMEN, TO
SHOW THE CONNECTIONS OP THE LUMBAR AND ABDOMINAL APONEUROSES, AND TIJE
SHEATH OF THE RECTUS MUSCLE.
A, at the level of the third lumbar vertebra ; B, the fore part, at a few inches above
the pubes.
a, spinous process of the third lumbar vertebra ; 5, body ; 1, section of the external
oblique muscle ; 2, internal oblique ; 3, transversalis ; 4, a dotted line to mark the
position of the fascia lining the abdomen ; 5, 5, in A, the anterior and posterior parts of
the sheath of the rectus, formed by the aponeurosis of the internal oblique splitting at its
outer edge 2' ; 6, points by two lines to the section of the rectus muscle in A and B ;
7, innermost layer of the lumbar aponeurosis, covering in front the quadratus lumber um,
and passing to the root of the transverse process ; 8, points to the section of the psoas
magnus and parvus muscles ; 9, the section of the erectores spinse muscles ; 9 + , the
middle layer of the lumbar aponeurosis passing to the extremity of the transverse process ;
10, 10 + , the posterior layer of the lumbar aponeurosis, connected with the latissimus
and serratus inferior : in A, at the sheath of the rectus, the aponeurosis of the external
oblique is seen to unite in front with the sheath, while that of the transversalis is seen
uniting with it behind : in B, the section is taken below the semilunar fold of Douglas,
where all the tendons pass in front of the rectus as at 5' ; the + near this, and in a
similar place in A, marks the middle line and the place of the union of the several
aponeuroses in the linea alba.
ACTIONS. The abdominal muscles not only form a great part of the wall to enclose
and support the abdominal viscera, but by their contractions are capable of acting
successively on those viscera, on the thorax, and on the pelvis. When the pelvis and
thorax are fixed, the abdominal muscles constrict the cavity and compress the viscera,
particularly if the diaphragm be fixed or be made to descend at the same time, as
occurs in vomiting and in the expulsion of the foetus, the faeces, and the urine.
FASCLE OF THE ABDOMEX. 257
If the vertebral column be fixed, these muscles press up the diaphragm, draw-
down the ribs, and contract the lower border of the thorax, and so contribute
to expiration ; but if the vertebral column be not fixed, the thorax will be bent
directly forwards, when the muscles of both sides act, or rotated to either side,
should they act alternately. Thus, if the external oblique of the right side be
made to act on the thorax, the first effect appears to be that of drawing its
margin down towards the pelvis; but, if the effort be continued, the trunk
will be rotated towards the opposite side. The left internal oblique may co-
operate in this action, for the direction of its fibres coincides with that of the right
external oblique.
If the thorax be fixed, the abdominal muscles may be made to act on the pelvis ;
thus, in the action of climbing, the trunk and arms being elevated and fixed, the
pelvis is drawn upwards, either directly or to one side, as a preparatory step to the
elevation of the lower limbs.
The attachment of the tendinous intersections of the rectus muscle to the anterior
wall of its sheath, causes the formation of corresponding transverse folds during its
contraction, and may enable the separate parts of the muscle to act on different
portions of the abdominal wall. By the same arrangement, when the oblique and
transverse muscles contract, the breadth of the recti will be maintained and even
increased ; and these muscles will thus be enabled, both in the straight and in the
incurved position of the abdominal wall, more effectually to compress the abdominal
viscera. The pyramidalis muscle assists the inferior part of the rectus.
FASCLE OF THE ABDOMEN.
The superficial fascia of the abdomen is usually described as consisting of
two layers. One of these, the subcutaneous layer, corresponds in its general
features with the areolar subcutaneous tissue of other parts of the body,
and contains embedded in it a very variable and often large quantity of fat.
The other, or deeper layer, is of a denser and more membranous structure,
contains a considerable amount of yellow elastic tissue in its substance, and
is united by intervening fibres, in some places very closely, to the aponeurosis
of the external oblique muscle. These two layers are both continuous with
the superficial fascia on other parts of the trunk : they can be dissected as
distinct layers only on the fore part of the abdomen, and are separated in a
more marked manner in the lower part of its wall, where subcutaneous ves-
sels, such as the superficial epigastric and circumflex iliac, lie between them.
The deep or elastic layer of the superficial fascia is bound down by a thin
but dense intervening layer of fibrous tissue to the aponeurosis of the
external oblique muscle in two places more particularly, viz., along the linea
alba from the umbilicus to the pubes, and in the whole length of Poupart's
ligament. At the lower part of the linea alba it sends fibrous and elastic
processes towards the dor.su rn of the penis, which form its so-called sus-
pensory ligaments. By its close union to Poupart's ligament, it comes into
relation with the fascia lata of the thigh, which is also united to that struc-
ture : but in the neighbourhood of the external inguinal aperture it remains
free, and is prolonged downwards over the spermatic cord to the scrotum.
The subcutaneous layer, losing its fat, is combined with the deeper layer as
they both pass to the scrotum ; and here the layer which they form acquires
a reddish brown colour, and undergoes a modification in structure by being
mingled largely with involuntary muscular fibres, and thus forms the dartos
tunic of the scrotum. Some involuntary muscular fibres also exist in the
altered superficial fascia which covers the penis. This covering, on leaving
the scrotum posteriorly, becomes continuous with the superficial fascia of
the perinseuni.
258 MUSCLES AND FASCIA OF THE ABDOMEN.
The parts of the superficial fascia here described have received minute attention
from surgical anatomists, because of their close relation to the seat of hernial
tumours : the adhesion of the fascia to Poupart's ligament, and its disposition over
the inguinal aperture, spermatic cord, and scrotum, while they prevent the descent
upon the thigh of matter which has been effused beneath the fascia, cause it rather to
spread upwards upon the abdomen or to take its course downwards upon the scrotum.
The deep layer of the abdominal fascia is also interesting, as corresponding with
the tunica abdominalis, a strong membrane consisting almost entirely of yellow
elastic tissue, which exists in animals, as may be well seen in the horse or ox, and
which contributes to the support of the viscera.
Lining fascia of the abdomen. On the inner surface of the wall of
the abdomen is a membranous structure which lines the visceral aspect of
the deepest stratum of muscles ; it. is divisible into two principal parts,
the fascia transversalis and fascia iliaca.
The fascia transversalis is named from its position on the deep surface of
the transversalis muscle. It is strongest and most clearly demonstrable in
the lower part, where the muscular and tendinous support is somewhat
weaker ; and here also it is of particular interest, on account of its forming
one of the coverings for inguinal hernia. Followed upwards from this
situation, the transversalis fascia becomes gradually less strong, and beyond the
margin of the ribs it degenerates into a thin covering for the under surface
of the diaphragm. Along the inner surface of the iliac crest, between the
iliacus and transversalis muscles, the fascia is attached to the periosteum.
For about two inches inwards from the anterior superior iliac spine, it is
closely connected with the posterior surface of Poupart's ligament, and is
there directly continuous with the fascia iliaca, a white line sometimes mark-
ing the place of continuity. At this place also, and to the same extent, the
fascia lata is closely united with both the fascia transversalis and Poupart's
ligament, which thuj serves as a line of union of several layers of fascia.
About midway between the iliac spine and the pubes, the external iliac
artery and vein, as they pass out into the thigh, intervene between the fascia
transversalis and the fascia iliaca, and from this point to the edge of Giin-
bernat's ligament the fascia transversalis is prolonged downwards under the
crural arch, and over the artery and vein, forming the anterior portion of
the funnel-shaped femoral sheath. This prolongation of the fascia trans-
versalis passes under Poupart's ligament, and is not very closely united
with it : it is strengthened by a dense band of fibres which arches over
the vessels, and is inserted into the pubic crest and pectineal line behind
the conjoined tendon of the transversalis and internal oblique. This
band is sometimes called the deep crural arch. It includes beneath it,
internal to the vessels, a space between Gimbernat's ligament and the
vein, sufficiently large to admit the point of the little finger ; this is
called the crural ring, and is the space through which femoral hernia
descends. About half way between the anterior superior iliac spine and
the symphysis pubis, and about half an inch above Poupart's liga-
ment, the spermatic cord in the male, or the round ligament in the female,
pierces the fascia transversalis. The opening thus made is called the internal
or deep abdominal ring, to distinguish it from the external or superficial
ring in the aponeurosis of the external oblique muscle ; the fascia above and
internal to it is thin, but below and external to it is firm and thick, and
forms a distinct crescentic margin, over which the cord or round ligament
passes ; from the borders of the opening a delicate funnel-shaped covering,
the infundibuliform fascia, is prolonged downwards on the emerging struc-
FASCLE OF THE PEEINJEUM. 259
tare, and forms in cases of oblique hernia one of the coverings of the
tumour.
The fascia iliaca, more limited in extent, but stronger than the fascia
transversalis, lines the back part of the abdominal cavity, and covers not
only the muscle from which it derives its name, but also the psoas. The
densest portion of its fibres is stretched transversely from the iliac crest,
over the margin of the psoas muscle to the brim of the pelvis, where it is
intimately blended with the periosteum. Superiorly, this membrane, be-
coming much weaker, is connected internally with the sacrum, and by
small and distinct processes with the intervertebral substances and the
neighbouring margins of the lumbar vertebrae ; and finally it becomes
blended with the fascia which covers the diaphragm and forms the liga-
inentum arcuatum externum. The external iliac vessels lie in front
of this part of the iliac fascia. To the outer side of those vessels, the
fascia turns forwards to be connected with Poupart's ligament and the
fascia trausversalis, as already described ; to the inner side of the femoral
vein it is attached to the ilio-pectineal line, where also the fascia lata, being
traced upwards, is found to terminate ; and between these two points,
namely, behind the femoral vessels, it continues downwards over the margin
of the pelvis, forming the back part of the sheath of those vessels, in the
same manner as its fore part is formed by the fascia transversalis.
The psoas parvus is closely connected with the iliac fascia, by means of
an expansion of its tendon.
At the back part of the abdomen is the aponeurosis of the quadratus
lumborum muscle, forming the anterior layer of the lumbar aponeurosis ;
this, together with the posterior and middle layers, has been already
described along with the transversalis muscle, with the aponeurotic origin of
which they are all connected.
FASCLE OF THE PERINEUM.
As a knowledge of the disposition of the fasciae of the perinssum and
pelvis assists the comprehension of the attachments and relations of the
muscles of those regions, the fasciae will here be first described.
Superficial Fascia. In the posterior half of the perinseum the sub-
cutaneous fat is continued deeply into the ischio-rectal fossa, the pyramidal
space intervening between the obturator fascia and the levator ani muscle,
lu the anterior half of the perinseum, beneath the subcutaneous fat, is placed
a special layer of fascia, continuous with the dartos, the proper superficial
perinceal fascia, sometimes called fascia of Colles. This fascia is bound down
on each side to the margin of the pubic arch as far back as the ischial tuber-
osity ; posteriorly, along a Hue from the ischial tuberosity to the central
point of the perinseum, it turns round the posterior margin of the trans-
versus perinsei muscle to join the subpubic fascia, to be presently described.
From its deep surface likewise, an incomplete septum in the middle line
dips down to the urethra and passes forwards into the scrotum. It thus
happens that air blown in beneath the proper perinseal fascia on one side
passes forwards and distends the scrotum to a certain extent on that side ; it
may then penetrate to the other also, and if injected with sufficient force
may reach the front of the abdomen and travel upwards beneath the super-
ficial fascia ; but it neither passes backwards to the posterior half of the
perinseum nor down upon the thighs. The same course is followed by urine
or matter extravasated beneath the proper peiinseal fascia.
8 9
260 FASCIA OF THE PERIK/EUM AND PELVIS.
The deep perinc&al or subpubic fascia is stretched across the pubic arch
on the deep surface of the crura of the penis and the bulb of the urethra.
It consists of two distinct layers of strong fibrous membrane, separated by
intervening structures. The anterior layer, or triangular ligament of the
urethra, attached to the inferior margin of the syinphysis pubis and to the
rami of the pubic and ischial bones, and extending in the middle line back
to the central point of the periuseum, is perforated about an inch from the
symphysis by the urethra, immediately before its expansion into the bulb,
and above and in front of this by the dorsal vein of the penis in the
middle line, and by the pudic arteries and nerves on each side. At its
posterior and inferior extremity it is connected with the deep layer,
and with the recurved margin of the perineeal fascia. Between the two
layers of the subpubic fascia are placed the membranous portion of the
urethra, the deep transverse and constrictor muscles of the urethra, and
Cowper's glands, together with the pudic arteries and nerves and the arteries
of the bulb. The posterior or deep layer consists of a right and left lateral
half, which are separated in the middle line by the urethra close to the neck
of the prostate, and are continued into the capsule of that gland. This
layer of fascia is superficial to the anterior fibres of the levator ani muscle,
which lie between it and the pelvic fascia, and is connected, not only with
the superficial layer, but likewise with a thin web of areolar tissue which
lies on the surface of the levator ani muscle, and is distinguished as the
anal fascia.
In the female the subpubic fascia is divided in the middle by the vagina.
EASCTJE OF THE PELVIS.
The fascia lining the pelvis is described in three parts, viz., the upper
part, or undivided pelvic fascia, and the two lower the recto-vesical fascia,
and the obturator fascia. The first of these is divided into the other two
at the level of a white band of fibres, stretched from the lower part of the
symphysis pubis to the spine of the ischium. The space between those two
fasciae is occupied by the levator ani and the fat and other contents of the
ischio-rectal fossa.
a. The pelvic fascia is attached at the side superiorly for a short space to
the brim of the pelvis, but in front of the line of its osseous attachment it
inclines downwards towards the lower part of the symphysis pubis, following
the margin of the obturator internus muscle. Anterior to the spine of the
ischium, it lies between the obturator internus and the peritoneum, and at
the back part of the pelvis is continued as a thin membrane over the
pyriformis muscle and the sacral nerves, and is perforated by branches of
the internal iliac artery and vein.
b. The recto-vesical fascia is the direct continuation of the pelvic fascia
downwards and inwards to the viscera, below the level of the white line
previously mentioned ; it descends, immediately in contact with the inner
surface of the levator ani muscle, to the prostate gland, the urinary bladder,
and the rectum. On reaching those organs it spreads over them, and
to some extent encases them. Close to the symphysis pubis, a short band
is directed backwards above the prostate gland, to the bladder, with which
it is intimately connected. A similar baud exists at the opposite side of
the symphysis pubis, and the two are separated by a narrow depression, in
which the dorsal veins of the penis lie, after entering the pelvis. The
bands in question are named the anterior true ligaments of the urinary
MUSCLES OF THE PERINEUM. 261
bladder. At the place where it is reflected inwards to the side of the
bladder, it forms the lateral true vesical ligament. At the side of the
bladder and prostate, the recto-vesical fascia gives a prolongation forwards
on the veins (prostatic) which cover the prostate, and is firmly adherent to
the capsule of that organ, except at its ba*e, where an angular furrow,
occupied by large veins, exists between the prostate and bladder, into this
furrow the incision for lithotomy ought not to extend, on account of the
danger from wounding the veins and from the infiltration of urine. A
portion of the recto-vesical fascia invests the vesiculse seminales, and is
extended across between the bladder and the rectum ; continuing into
the membrane of the opposite side, it supports the bladder, and separates
that organ from the intestine. On the rectum the fascia is also reflected
upwards and downwards, gradually degenerating into a thin membrane over
the surface of the bowel, as it likewise does on the bladder.
c. The obturator fascia is a membrane stretched over the lower part of
the surface of the obturator internus muscle within the pelvis. It is
connected superiorly with the white band before referred to, which consists
indeed of its superior fibres, and it is attached in the rest of its circumference
to the rami of the pubis and ischium, the ischial tuberosity, and the greater
and lesser sacro-sciatic ligaments. It lies between the obturator internus
muscle and the ischio-rectal fossa, and presents in its substance towards
the muscle a canal, which contains the internal pudic artery and nerve in
their course to the perinseum.
The obturator fascia is sometimes included in the description of the pelvic fascia,
while the recto-vesical is considered as an offset from it. It will be found, however,
on dissection, that the recto-vesical fascia is always most directly continuous with the
pelvic fascia, and that the obturator fascia is only loosely connected with it. Indeed,
the fibres of the levator ani muscle in most cases pass upwards to some extent beyond
the white line, and thus separate the obturator from the pelvic fascia.
The ischio-rectal fossa is a pyramidal space occupied by subcutaneous fat.
It is bounded externally by the obturator fascia, posteriorly by the gluteus
maximus muscle and great sacro-sciatic ligament, and internally by the
recto-vesical fascia ; anteriorly, its base is limited by the margin of the
perinseal and the subpubic fasciae.
In the female, the pelvic fascia is connected with the vagina in the same
manner as with the other pelvic organs.
MUSCLES OF THE PERINEUM.
The muscles of the perinseum differ somewhat in the two sexes, and must
therefore be separately described in each. In both sexes they may be
divided into two groups, according as they are more immediately connected
with the lower orifice of the alimentary canal or with the genito-urinary
outlet. In both groups superficial and deep muscles are to be distin-
guished.
A. IN THE MALE.
a. ANAL GROUP. The internal or circular sphincter is a thick ring of
uustriped muscle connected with the lowest circular fibres of the rectum,
which will fall more naturally to be considered along with the anatomy of
that organ.
262
MUSCLES OF THE PERIX^EUM.
The superficial or external sphincter is a thin lay'er of fibres placed
Immediately beneath the skin surrounding the margin of the anus. It
is elliptical in form, about half an inch in breadth on each side of the
anus, and is attached posteriorly by slight tendon to the tip and back of
the coccyx ; passing forwards on each side of the anus, it becomes blended
anteriorly with the transverse and the bulbo-cavernosus muscles at the
central point of the perinceum, a name given to the depressed spot situated
in the male between the anus and the bulb of the urethra, and in the female
between the anus and vulva.
Fig. 202. SUPERFICIAL VIEW OP
THE MUSCLES OF THE PERINEUM
IN THE MALE (modified from
Bourgery). \
a, crest of the pxabis ; the penis
cut short at this place ; &, coccyx ;
c, placed on the tuberosity of the
ischium, points by the line to the
greater sacro-sciatic ligament ; x ,
placed within the anus ; 1, placed
on the spongy body of the urethra,
in front of the bulbo-cavernosus
muscles ; 2, placed on the central
point or tendon of the perinseum,
marks the posterior extremity of the
same muscles ; 3, ischio-cavernosus ;
4, transversus perinaei ; 5, levator
ani ; from 2 to 6, elliptical sphincter
of the anus ; surrounding x , the
circular sphincter is indicated ; 6,
coccygeus muscle ; 7, adductor lon-
gus ; 8, gracilis ; 9, adductor mag-
nus ; 10, semitendinosus and biceps ;
11, on the left side, the gluteus raaxi-
mus entire ; 11', the same cut on the
right side, so as to expose a part of the coccygeus muscle.
The levatores ani and coccygei are two expanded muscles continuous one
with the other, which together form a floor of support for the pelvic viscera,
and close in a great measure the lower orifice of the pelvis.
The levator ani arises in front from the posterior surface of the pubes,
near the symphysis and midway between its upper and lower borders ;
behind from the spine of the ischium, and between those points from the
pelvic fascia along the line of attachment of the obturator fascia. Some of
its fibres are also traceable upwards in the substance of the pelvic fascia
above the level of the obturator.
From this extensive origin the fibres of the levator proceed downwards
and inwards towards the middle line of the floor of the pelvis. Its posterior
fasciculi are inserted upon the side of the lower end of the coccyx ; the
bundles immediately in front of the coccyx unite in a median raphe with
those of the opposite sides as far forward as the margin of the anus ; the
middle and larger portion of the muscle is prolonged upon the lower part of
the rectum, where it is connected with the fibres of the external sphincter,
and slightly with those of the internal ; and lastly, the anterior muscular
bundles pass between the rectum and the genito-urinary passages, and,
descending upon the side of the prostate, unite beneath the neck of the
COCCTGEUS TRANSVERSUS PERIN^EI.
263
bladder, the prostate, and the neighbouring part of the urethra, with cor-
responding fibres from the muscle of the opposite side, and blend also with
those of the external sphincter and deep transverse perinseal muscles.
The anterior portion of the levator ani, which arises from the ramus of
the pubes, close to the symphysis and above the pubic arch, and also from
the adjacent fasciae, is sometimes separated at its origin by areolar tissue
from the rest of the muscle. From this circumstance, and from its connec-
tion with the prostate gland, it was described by Santorini, and since by
AJbinus and Scemmerring, as a distinct muscle, under the name of the
levator prostatce. Its fibres pass backwards parallel with the middle line.
The upper or pelvic surface of the levator ani is in contact with the recto-vesical
fascia, the capsule of the prostate, and the lower end of the rectum. The under or
perinseal surface, invested by the thin anal fascia, is covered by the fat which occupies
the ischio-rectal fossa. The posterior border is continuous with the coccygeus.
Fig. 203. LEFT HALF OF THE MALE
PELVIS, TO SHOW THE LEVATOR ANI AND
COCCYGEUS MUSCLES (after Cloquet).
o, the promontory of the sacrum ; &,
the crest of the pubis ; c, the last bone of
the coccyx ; d, the spine of the ischium ;
e, the symphysis pubis ; /, a small portion
of the anal part of the rectum ; g, half
the prostate gland ; A, half the bulb and
a portion of the penis with the urethra,
&c. ; 1, upper part of the obturator in-
temus muscle exposed by removing from
within it the pelvic fascia ; 2, coccygeus
muscle, and above it and between it and d,
the sacro-sciatic ligaments ; 3, inner surface
of the levator ani ; the white line extending
between d and e, shows the place of its
origin from the fascia of the pelvis ; below
is shown the descent of its fibres to the anus
and to the portions of the periiiaeum before
and behind it.
Fig. 203.
The coccygeus muscle is composed of fleshy and tendinous fibres, forming
a thin, flat, and triangular sheet, which arises by its apex from the spine of
the ischium and the lesser sciatic ligament, and is attached along its base to
the border of the coccyx and the lower part of the sacrum. The fibres of
this muscle diverge as they approach the middle line, while those of the
levator ani rather converge as they descend.
The internal or pelvic surface of this muscle assists in supporting the rectum ; its
external or under surface rests on the front of the sacro-sciatic ligaments, and on the
gluteus maximus muscle.
The levatores ani and coccygei muscles together have been named somewhat appro-
priately by Meyer, the pelvic diaphragm.
6. GENITOURINARY GROUP. Covered by the special fascia of the perinseum
are three muscles, placed superficially the transverse (superficial transverse),
the ischio-cavernosus, and the bulbo-cavernosus ; while, situated more deeply
between the superficial and deep layers of the subpubic fascia, are the deep
transverse musclo and the constrictor of the urethra, sometimes described as
one muscle under the name of compressor of the urethra.
264 MUSCLES OF THE PERINJEUM.
The transversus perinwi muscle arises from the inner surface of the pubic
arch, near the ischial tuberosity, and is directed obliquely forwards and
inwards to unite with the muscle of the opposite side, as well as with the
sphincter ani and bulbo-cavernosus at the central point of the perinseum.
It lies immediately in front of the line where the perinseal dips back to join
the subpubic fascia. It is sometimes absent, and at other times one or
more small muscular slips are found lying on the same plane with it, in
front or behind.
The ischio-cavernosus, or erector penis muscle, embracing the crus penis,
arises from the inner part of the tuber ischii, behind the extremity of the
crus penis, and from the pubic arch along the inner and outer sides of
the crus. From this origin the fleshy fibres are directed forwards to a
tendinous expansion which is spread over the lower surface of the crus penis,
and is inserted into the under and outer surfaces of that body towards the
fore part.
This muscle serves to compress the crus penis, with which its tendinous fibres are
blended, and thus it contributes to produce, or at least to maintain, the erection of
the penis.
The muscles of the two sides have been described by Krause as in some cases con-
nected by a thin tendinous expansion, which, according to that anatomist, extends
along the outer side of the penis over the dorsal surface of the organ, and at the same
time over the vessels lying upon it (Mtiller's Archiv, 1832) : but this connection
between the muscles has been in vain sought for by Theile and by Kobelt (Die m'ann-
lichen und weiblichen Wollust-Organe, 1844). By Houston there have also been
described (Dublin Hosp. Reports, vol. v.), under the name of compressors venae,
dorsalis penis, two slips of muscle, separated from the erectores penis on each side
by an interval, though apparently belonging to them. They are said to arise from
the pubic arch, above the origin of the erector muscles and the crura of the penis,
and, passing upwards and forwards, are inserted above the dorsal vein, by joining each
other in the middle line. These muscles, which are well developed in the dog and
several other animals, are by no means constant in the human subject.
The bulbo-cavernosus, accelerator urinse, or ejaculator seminis, may be con-
sidered as a single muscle, consisting of two symmetrical parts.
The fleshy fibres of the muscle take origin behind from the central tendon
of the perinseum, and from a median tendinous raphe' interposed between
the two halves of the muscle. The larger number of the fibres are directed
round the bulb and the adjoining part of the corpus spongiosum urethrre,
and join above that body with those from the opposite side by a strong
aponeurosis. At the fore part, a portion of the muscle passes over the
sides of the corpus cavernosum, and is attached to that body in front of the
erector penis : from its insertion a tendinous offset is said to be prolonged
over the dorsal vessels of the penis (Kobelt). The posterior fibres, shorter
than the anterior, are inserted into the front of the triangular ligament.
The fibres which invest the most prominent part of the bulb are more or less dis-
tinct from those contiguous to them, and have been described by Kobelt as forming a
separate muscle, to which he has given the name compressor hemisphcerium bulbi.
The fibres of this muscular slip are connected by a small tendon, above the urethra,
with the corresponding part of the opposite side.
This muscle compresses the bulb and the adjoining part of the corpus spongiosum
of the urethra, so as to evacuate fluid lodged in the canal, as well as to increase the
turgescence of the glans during erection.
The deep transversus perincei muscle is a thin rather inconstant fasciculus,
which, arising from the margin of the pubic arch, is directed inwards and
CONSTRICTOR URETHRA MUSCLE.
265
meets with its fellow of the opposite side behind the bulb, at the central
point of the perinseum. Its fibres conceal Cowper's gland.
The constrictor urethrcc muscle consists of a number of transverse fibres
extending across the arch of the pubis, some of them above and others
below the membranous portion of the urethra, and closely embracing it. In
some bodies a tendinous raphe, placed over the middle of the urinary canal,
separates each stratum into lateral halves.
This muscle rests in contact with the deep layer of the triangular ligament, which
separates it from the anterior fibres of the levator ani.
The transverse constrictor of the urethra was known to Santorini. One of the
representations of it, contained in his posthumous work, has been copied for the
woodcut (Fig. 204). Indistinctly or partially noticed by other anatomists, the
muscle was first fully described by Guthrie ; and the whole of the muscular structure
connected with the membranous part of the urethra was examined about the same
time by Mliller, but the results were not published till a later period. (Guthrie,
"Anatomy and Disease of the Neck of the Bladder," &c., 1834; Johannes Miiller,
" Ueber die organischen N erven der erectilen mannlichen Geschlechts-Organe/' &c.
1836.)
Fig. 204.
Fig. 204. POSTERIOR VIEW OP THE PUBES,
WITH PART OP THE BLADDER AND
URETHRA ATTACHED (from Sautorini).
1, body ; 2, rami of the pubes ; 3,
obturator interims muscle ; 5, poi'tion of
the fundus and neck of the bladder laid
open ; 6, the prostate gland ; 7, trans-
verse fibres of the compressor urethrse
muscle, passing above the urethra; 8,
similar fibres passing beneath that canal.
Circular fibres of Santorini (stra-
tum internum circulare, Miiller).
Beneath the transverse muscle just
described is a series of circular in-
voluntary muscular fibres, entirely
surrounding the membranous part
of the urethra : these are continuous
behind with the circular fibres of
the prostate, and are referred to in
the description of that body. (See Structure of the Prostate. )
A pubo-urethral muscle was described by James Wilson (Medico-Chirurgical Trans.,
London, vol. i. p. 176), and is sometimes referred to as Wilson's muscle, but has not
been recognised as a separate muscle by succeeding anatomists who have given
special attention to the subject of the muscular structures round the urethra. An
unstriped pubo-vesical band has been described, descending from the back of the sym-
physis to the neck of the bladder (Luschka).
B. IN THE FEMALE.
In the female the anterior fibres of the levator ani embrace the vagina as
they do the prostate in the male.
The transversus perincei and the sphincter ani are arranged nearly in the
same manner as in the male.
266
MUSCLES OF THE LOWER LIMB.
The erector ditoridis differs from the erector penis of the male by its
smaller size alone.
The sphincter vaginas is attached behind to the central point of the
perinaeum, in common with the sphincter ani and transversus perinsei
muscles ; its fibres open out to surround the vaginal orifice and vestibule,
closely embracing on the outer side the two bulbs of the vestibule ; again
Fig. 205. Fig. 205. MUSCLES OP THE PERINEUM IN
THE FEMALE. j
a, clitoris ; 6, cms clitoridis ; c, is placed
in the vestibule above the orifice of the
urethra ; d, vagina ; x , anus ; e, coccyx ;
1 , external sphincter ani muscle ; 2,
sphincter vaginae; 2', a few of its fibres
prolonged to the clitoris ; 3, levator ani ;
4, on the left ischial tuberosity, points to
the transversus perinei (the inner fibres of
this muscle are represented too far forwards
in the figure) ; 5, 6, ischio-cavernosus ;
7, gracilis ; 8, adductor magnus and semi-
tendinosus, &c. ; 9, gluteus maximus.
approaching each other in front, they
become narrow, and are inserted
upon the corpora cavernosa of the
clitoris, a fasciculus crossing over
these and including the vena dorsalis.
The two halves of this elliptical mus-
cle appear to correspond strictly to those of the bulbo-cavernosus muscle in
the male.
A deep transverse muscle, corresponding to part of the constrictor urethrse
of the male, has been described as resting on the pubic surface of the female
urethra.
MUSCLES OF THE LOWER LIMB.
The muscles which pass between the trunk and the lower limb, viz., the
psoas, pyriformis and coccygeus, are so few in number and so intimately
connected with others, that it is inexpedient to describe them as a distinct
group, as has been done in the case of the more numerous and considerable
muscles which attach the upper limb to the trunk.
MUSCLES OF THE HIP AND THIGH.
GLUTEAL REGION. The muscles of this region are the three glutei, the
pyriformis, the obturator externus, the obturator internus with the gemelli,
and the quadratus femoris.
The gluteus maximus is a very large and coarsely fasciculated muscle,
somewhat quadrilateral in shape, which forms the greatest prominence of the
gluteal region posteriorly. It arises from the posterior fifth of the iliac
crest, and the irregular rough surface of the ilium subjacent to that part ;
from the posterior surface of the last piece of the sacrum ; from the great
sacro-sciatic ligament and the side of the coccyx ; and between the sacrum
and the ilium, from the aponeurosis of the muscles of the back. Thence
it passes downwards and outwards ; the fibres of its lower third are inserted
GLUTEI MUSCLES.
267
into an elongated rough impression, extending between the base of the great
trochanter and the linea aspera ; and those of the upper two-thirds into a thick
tendinous structure, which covers the great trochanter, and joins the fascia
lata of the thi^h : a few of the lowest fibres terminate also iu the fascia.
Fig. 206.
Fig. 206. SUPERFICIAL MUSCLES OP THE HIP
AND THIGH, SEEN PROM BEHIND.
1, gluteus medius, covered by the strong fascia
lata ; 2, middle of the gluteus maximus ; 2',
placed on the fascia lata below the place where the
gluteus maximus is inserted into it, and above
the insertion of the muscle into the femur ; 3,
vast us externus ; 4, biceps flexor cruris ; 4',
tendon of the biceps, receiving en its outer side
the oblique fibres of the short part ; 5, semi-
tendinosus ; 5', its tendon near the insertion ;
6, semimembranosus, its tendon of insertion is
seen between 5' and 7"; 7, gracilis; 7', tendon of
the gracilis near its insertion ; 8, small part of
the sartorius ; 9, small portion of the adductor
magnus ; 10, outer, and 11, inner head of the
gastrocnemius ; 12, placed in the popliteal
space, points to the origin of the plantaris.
At the upper and lower borders of this
muscle, the fascia lata, or aponeurosis of the
limb, splits into two thin layers, which are
continued, one on the deep, and the other on
the outer surface, so as to enclose the muscle.
A few fibres on the upper border of the muscle
arise from the deeper of those two layers :
the lower border, longer and looser, lies in the
fold of the nates. The deep surface rests on
the gluteus medius and pyriformis muscles,
the tendon of the obturator internus, with
the two gemelli, the quadratus femoris, a
small portion of the adductor magnus, the
great trochanter, the ischial tuberosity, and
the origins of the hamstring muscles ; it
covers also the sciatic artery and nerves as
they emerge from the pelvis below the pyri-
formis, the superficial branch of the gluteal
artery passing out above that muscle, and
the pudic artery and nerve lying behind the
spine of the ischium.
Between the tendon of the muscle and
the great trochanter of the femur, are placed
two or three synovial bursae, or a single
multil ocular bursa of large size. A bursa is
also situated between the muscle and the
tendon of the vastus externus, and another
separates it from the tuber ischii.
The great size of the gluteus maximus
and the consequent prominence of the
buttock, is a characteristic of man as com-
pared with those animals which most nearly
approach him in general structure.
The gluteus medius, covered paitly by the gluteus maximus, partly by the
fascia lata, arises from the surface of the dorsum ilii above the superior
2G8
MUSCLES OF THE LOWER LIMB.
curved line, and in front of the gluteus maximum, from the strong fibres of
the fascia lata covering its outer surface. The muscular fibres converge
as they descend, the anterior fibres passing obliquely backwards, the poste-
rior fibres obliquely forwards, and terminate in a fan-shaped tendon, which,
becoming narrowed and thick, is inserted into the oblique line directed
downwards and forwards on the outer surface of the great trochanter. The
tendon is separated by a small bursa from the upper part of the trochanter,
Anteriorly there is no separation between this muscle and the gluteus
minimus on w r hich it lies, the two muscles running into one another at
their common anterior border, and separating only at their tendons of
insertion.
Between this muscle and the gluteus minimus are the gluteal nerve and deep
branches of the gluteal artery.
Fig. 207.
Fig. 207. DEEP MUSCLES OP THE HIP
AND PELVIS ON THE LEFT SIDE, FROM
BEHIND. \
The gluteus raaximus and the muscles of
the thigh have been removed. 1, gluteus
raedius ; 2, pyriformis ; 3, gemellus su-
perior ; 4, gemellus inferior ; 5, obturator
internus, seen partially within the pelvis,
and, after issuing by the lesser sciatic notch,
between the gemelli muscles ; 6, quadratus
femoris ; 7, tendon of the obturator ex-
ternus between the gemellus inferior and
quadratus.
The gluteus minimus, covered by
the preceding muscle, arises from the
whole space on the dorsum ilii be-
tween the superior and inferior curved
lines. The fibres, converging as they
descend, terminate in an aponeurotic
expansion, superficial to the muscle,
and become narrowed into a tendon
which is inserted into an impression
on the anterior border of the great
trochanter. The tendon is bound
down to the prominence of the trochauter by a strong fibrous band which
joins it from the upper margin of the capsule of the hip-joint. A synovial
bursa is interposed between the tendon and the trochanter.
The pyriformis muscle arises within the pelvis by three fleshy digitation^
from the second, third, and fourth divisions of the sacrum, between the
anterior sacral foramina, slightly from the deep surface of the iliac bone,
near the sacro-sciatic notch, and from the sacro-sciatic ligament. The
muscle passes out of the pelvis by the great sacro-sciatic notch, and is
inserted by a rounded tendon into the upper border of the great trochanter,
being bound down for some distance from the point of its final insertion to
the subjacent tendon of the obturator internus and gemelli muscles.
The pyriformis muscle, after escaping from the pelvis, is in contact by its upper
border with the gluteus medius and minimus, the gluteal vessels and nerve inter-
vening ; and by its lower border with the superior gemellus muscle, the sciatic vessels
and nerves, which emerge beneath it, lying between. The muscle is frequently
pierced by part of the great sciatic nerve, and is thus divided more or less completely
into two parts.
OBTURATOR MUSCLES QUADRATUS. 269
The obturator internus muscle, in great part lodged within the pelvis,
arises from the deep surface of the obturator membrane ; from the fibrous
arch which completes the canal for the obturator vessels and nerves ; from
a naiTow strip of the bone internal to the obturator foramen ; from the
posterior surface of the membrane occupying that aperture, extending on the
bone downwards to the outlet, backwards as far as the sciatic notch, and
upwards to the brim of the pelvis ; it also arises to some extent from the
obturator fascia, which is in contact with the deep surface of the muscle. Its
fibres converging as they proceed backwards from this origin, the muscle
emerges from the pelvis by the small sacro-sciatic foramen, turns over on
the trochlear surface of the ischium, and is directed outwards, to be inserted,
in connection with the gemelli, into the upper part of the digital fossa of
the great trochanter. The tendon of the muscle is formed by the union of
four or five bands, occupying the surface of the muscle which is towards
the bone, and lying side by side as they turn over the trochlear groove :
their motion in that groove is facilitated by a synovial bursa, which sends
in processes between them, and by a thin coating of cartilage on the trochlear
surface of the bone. Another bursa, of much smaller size, elongated and
narrow, is placed between the tendon and the fibrous capsule of the hip-
joint. These bursse are sometimes continuous with one another.
The gemelli (gemini) are two small narrow muscles, consisting chiefly of
fleshy fibres extended horizontally at each side of the tendon of the obturator
internus ; and they are named from their position above and below that tendon.
The gemellus superior, which is usually the smaller muscle, arises from the
ischial spine ; the gemellus inferior takes origin from the upper and back
part of the tuberosity of the ischium. Passing outwards, they join the
tendon of the internal obturator muscle, which is placed between them,
covering and concealing it more or less, and along with it are inserted into
the digital fossa of the trochanter. Some of their fibres, especially from
the superior gemellus, run obliquely into the tendon of the obturator.
The superior gemellus is placed immediately below the pyriformis ; the inferior
gemellus is above the quadratus femoris, and at its insertion is close to the tendon of
the obturator externus muscle. These muscles may be regarded as portions of the
obturator internus arising externally to the pelvis. The gemellus superior is often
very small, and in some cases is altogether absent.
The quadratus femoris, of an oblong figure, arises from the external border
of the tuber ischii, and, proceeding horizontally outwards, is inserted into
the greater part of the linea quadrati on the posterior surface of the great
trochanter of the femur.
Superiorly this muscle is close to the inferior gemellus. Its inferior border is in
contact, at its origin, with the descending fibres of the adductor magnus, and at its
insertion with the superior or horizontal fibres. It conceals the outer part of the
obturator externus, and also the lesser trochanter, which is separated from it by a
small bursa.
The obturator externus, arising from the anterior two- thirds of the surface
of the obturator membrane, and from the outer surface of the rami of the
pubes and ischium as far as the margin of the thyroid foramen, encroaching
also a little upon the body of the pubes, and spreading towards the tuberosity
of the ischium, extends horizontally outwards and backwards, converging to
a tendon which is directed along the under and hinder surface of the neck
270
MUSCLES OF THE LOWER LIMB.
of the femur to bo inserted into the trochauteric fossa below the obturator
interims and geinelli.
POSTERIOR FEMORAL REGION.
(The Hamstring Muscles).
At the back of the thigh are three
long flexor muscles of the knee-joint,
viz., the biceps, semitendinosus, and
semimembranosus.
The biceps flexor cruris consists of two
parts, arising one from the hip-bone,
the other from the femur, and uniting
inferiorly to terminate an the fibula.
The long head arises by a tendon com-
mon to it and the semitendinosus from
the most prominent part of the ischial
tuberosity, and the muscular fibres ter-
minate below the middle of the thigh in
an aponeurosis which is continued down
into the tendon of insertion. The short
head arises from the rough surface of the
linea aspera in its whole extent, from a
part of the line leading from thence to
Fig. 208. DEEP MUSCLES OP THE RIGHT HIP
AND THIGH, FROM BEHIND.
a, anterior, a', posterior superior spine of
the ilium ; b\ posterior inferior spine ; c, c,
great and small trochanter; d, symphysispubis;
c, tuberosity of the ischium ; /, flat or popli-
teal surface of the femur ; g, head of the
fibula ; 1, gluteus minimus ; 2, obturator in-
ternus passing out of the pelvis by the lesser
sciatic notch to the digital fossa of the tro-
chanter : the gemelli muscles have been re-
moved ; 3, obturator externus ; 4, small part
of the back of the pectineus and adductor
brevis ; 5, origin of the adductor magnus
from the lower part of the ischial tuberosity ;
5', 5', line of insertion of this muscle on the
linea aspera, in which are seen three arched
tendinous intervals for the passage of the per-
forating vessels ; 5", tendon of insertion into
the inner tuberosity of the femur ; between the
lower 5' and 5", the interval through which
the femoral vessels pass into the popliteal space ;
the upper 5' is placed upon the cut end of
quadratus femoris ; 6, vastus externus ; 7,
vastus internus ; 8, femoral head of the biceps
femoris : the lower part is represented as pass-
ing too far inwards ; 8', its ischial head, cut
short ; 9, plantaris muscle : at its upper end
the outer head of the gastrocnemius ; the
figure 5" is upon the cut inner head ; 10, pop-
liteus, cut short below ; 11, tendon of the semi-
membranosus; 12, upper part of the soleus.
the outer condyle, and from a part of the adjacent flat surface of the femur ;
HAMSTRING MUSCLES ILIO-PSO AS. 271
also from the external intermuscular septum between it and the vastus
extermis muscle, and terminates on the same aponeurosis as the long head.
The inferior tendon is inserted into the head of the fibula by two portions,
between which is attached the external lateral ligament of the knee-joiDt,
being separated from them by a synovial bursa. Some of the fibres of the
tendon, passing forwards and downwards, are inserted into the front of the
tibia, and others passing backwards strengthen the fascia of the leg.
The semitendinosus muscle, arising from the tuberosity of the ischium by
the tendon common to it and the biceps, for a distance of about three
inches, descends on the back of the thigh, and terminates below the middle
in a long, rounded, and slender tendon, which passes along the inner side of
the popliteal space, resting on the semimembrauosus, and curves forwards to
be inserted in an expanded form into the upper part of the tibia at its
inner side. There the tendon is on the same plane, but below that of the
gracilis, both being under cover of the sartorius. A narrow oblique tendi-
nous intersection traverses the muscle about the middle.
The semimembrauosus muscle arises from the tuberosity of the ischium,
above and to the outside of the origin of the biceps and semitendinosus, by a
strong flattened tendon, two or three inches long, which as it descends in
front of the common tendon of those two muscles, passes to their inner side.
It terminates inferiorly in a thick tendon, which is inserted in three parts :
the principal part turns forwards and is inserted into a well marked groove
on the inner tuberosity of the tibia, beneath the internal lateral ligament of
the knee-joint, some of its fibres joining that ligament ; a second part, passing
downwards and outwards, expands in the aponeurosis over the popliteus
muscle ; and the remaining fibres are directed upwards and outwards, and
blend with the posterior ligament of the knee-joint, of which they may be
said to form a considerable portion. The muscle consists of numerous short
fibres extending obliquely between two aponeurotic expansions, which are
continued upwards and downwards on the opposite sides of the muscle for
three fourths of its length from the superior and inferior tendons.
The inferior tendon of the semimembranosus muscle is separated from the tendon
of the inner head of the gastrocnemius by a large bursa. The muscle rests on the
adductor magnus.
The hamstring muscles descend in contact with one another, being bound down by
the fascia lata ; but inferiorly they diverge, the biceps passing to the outside, and the
semimembranosus and semitendinosus to the inner side of the knee, forming the supe-
rior borders of a diamond-shaped hollow at the back of the knee the popliteal space.
The great sciatic nerve is concealed by them while they are in contact, and its
principal division, the internal popliteal, lies in contact with the semimembranosus
muscle in the popliteal space, while the smaller or external popliteal division runs
along the edge of the biceps muscle.
ILIAC REGION.
The ilio-psoas muscle, the great flexor of the hip-joint, is divisible into two
parts, a broad outer part, the iliacus, and an elongated inner part, the psoas
magnus, which are inserted together into the small trochanter.
The iliacus muscle arises from the iliac fossa of the innominate bone, and
from the anterior border of the same, likewise from the base of the sacrum,
the ilio-lumbar ligament, and the capsule of the hip-joint. Its fibres con-
verging, as they pass downwards and inwards, are inserted for the most part
into a tendon continuous with the psoas muscle ; while some are prolonged
to a special triangular impression on the upper part of the femur, in front of
and below the small trochanter.
272
MUSCLES OF THE LOWER LIMB.
The psoas magnus arises from the upper and lower lateral parts of the
bodies of the last dorsal and of all the lumbar vertebrae, from the interposed
fibro- cartilages, and from the anterior surface and lower margin of the
transverse processes of the lumbar vertebrae near their bases. It forms a
thick elongated muscle, and is inserted into the small trochanter of the
femur by means of a tendon, which is placed at first within the substance of
the muscle, and afterwards at its outer side, receiving in this manner the
fibres of the iliacus as well as those of the psoas.
Fig. 209.
Fig. 209. DEEP DISSECTION OP THE MUSCLES OF THE ABDOMEN AND PELVIS.
a, twelfth dorsal vertebra ; b, fifth lumbar vertebra ; c, transverse process of the first
lumbar vertebra ; 1, quadratus lumborum muscle ; on the left side, its fibres of origin
from the transverse processes of the lumbar vertebrae are shown by the removal of the
psoas muscles ; 2, placed upon one of the intertransversales muscles of the left side ; 3,
marks the upper part of the psoas parvus, drawn somewhat to the outer side ; 3', the
insertion of its tendon into the brim of the pelvis ; 4, points to the upper part of the
paoas magnus ; 4", one of the origins of the muscle ; 4', the insertion of the muscle into
the lesser trochanter of the femur ; 5, iliacus internus, shown fully on the left side by
the removal of the psoas muscles ; 5', insertion of the iliacus muscle into a Hue below
the trochanter minor ; 6, pyriformis muscle of the left side rising within the pelvis from
the sacrum ; 6', insertion of its tendon into the summit of the great trochanter; 7, the
obturator externus seen from before on the left side ; + +, the right and left tendinous
pillars of the diaphragm on the front of the upper lumbar vertebrae.
MUSCLES IN FRONT OF THE THIGH. 273
The connection of the psoas with the bodies of the bones is effected by means of
five distinct parts, each of which is attached to the upper and lower margins of two
vertebrae and the interposed fibro-cartilage ; the highest to the neighbouring margins
of the last dorsal vertebra and the first lumbar, and the lowest to the edges of the
fourth and fifth lumbar vertebrae with the intervertebral substance. These attach-
ments are connected by thin tendinous arches, extending over the middle of each
vertebra, covering the lumbar vessels and communicating branches of the sympathetic
nerve, and giving origin to other muscular fibres. The psoas muscle, at its superior
extremity, passes behind the diaphragm, below the arch of the ligamentum arcuatum
internum. Resting on its inner border, along the margin of the pelvis, is the external
iliac artery, and deeply in the substance of the muscle is the lumbar plexus of nerves.
The ilio-inguinal and external cutaneous nerves cross the iliacus muscle, and the
anterior crural nerve descends on the tendon of the psoas. The iliac fascia extends
over the surface of the whole ilio-psoas muscle in the abdomen. The muscle emerges
from the abdomen beneath Poupart's ligament, and turning over the brim of the
pelvis rests on the capsule of the hip-joint, on which it glides by means of a large
synovial bursa, which occasionally communicates with the interior of the joint ; its
outer margin is in contact with the rectus muscle, and its inner margin is separated
from the pectineus by the internal circumflex artery.
The psoas parvus, an occasional muscle, placed on the surface of the
ppoas magnus, arises from the bodies of the last dorsal and first lumbar
vertebrae, and from the fibro-cartilage between them, and soon ends in a
flat tendon, which passes along the front and the inner side of the psoas
magnus, to be inserted into the ilio-pectineal line and eminence.
This muscle, although it is well developed and constant in animals, is most fre-
quently absent in the human subject. It was found in only one of twenty bodies
examined by Theile with special reference to its existence. When present, it is
liable to many changes in the place of origin ; thus, it may be connected only with
the first lumbar vertebra, or with the second and the intervertebral substance above
it, and it has been observed to commence by two parts or heads separated by an
interval.
ANTERIOR FEMORAL REGION.
The tensor vagina femoris, or ilio-aponeurotic muscle of the thigh, arises
by muscular and tendinous fibres from the external surface of the iliac crest
close to its fore-part, and from part of the notch between the two anterior
iliac spines, external to the attachment of the sartorius ; and passing down-
wards and a little outwards it is inserted between two laminse of the fascia
lata, about three inches below the great trochanter of the femur. The
outer of these laniinsB is continued upwards on the muscle in its whole
extent, being part of the general investment of the limb, the deeper is
connected above with the origin of the rectus muscle, and with the fibres
attaching the gluteus minimus to the hip-joint. The part of the fascia,
made tense by the action of the muscle, forms a strong tendinous band,
which descends to the outer and back part of the knee-joint.
The sartorius is very long, narrow, and ribbon -shaped, and presents the
longest fibres of all the muscles in the body : it arises by a short tendon
from the anterior superior spiuous process of the ilium, and from a small
part of the anterior margin of that bone immediately below, and, passing
downwards and inwards across the front of the thigh, is inserted by an
expanded aponeurosis into the upper and inner side of the tibia, near to the
tubercle, and for about an iuch below it.
In this long course the muscle is directed over the anterior part of the thigh,
obliquely inwards in the upper third, and vertically at the inner aspect of the limb
T
274
MUSCLES OF THE LOWER LIMB.
as far as the knee ; below this it turns obliquely forwards to its place of attachment.
The tendon of insertion, broad and expanded, covers the tendons of the gracilis
and semitendinosus (a synovial bursa being interposed), and gives off one expansion
which strengthens the capsule of the knee-joint by becoming incorporated with it,
and another which blends with the fascia of the leg.
Fig. 210.
Fig. 210. SUPERFICIAL MUSCLES OF THE
FRONT OP THE THIGH.
a, anterior part of the crest of the ilium ;
b, symphysis pubis ; c, patella ; d, is below
the anterior tuberosity of the tibia ; 1, points
to the insertion of the external oblique muscle
into the iliac crest ; 2, its aponeurosis at the
linea semilunaris ; 3, the external abdominal
ring ; 4, part of the gluteus medius ; 5, tensor
vaginae femoris at the place of its insertion
into a portion of the fascia lata, which has
been removed between 5 and 5', which latter
part is seen descending to be attached to the
tibia and fibula ; 6, the sartorius ; 6', the
insertion of the sartorius ; 7, psoas and iliacus
conjoined ; 8, pectineus ; 9, adductor longus ;
10, gracilis ; 11, part of the adductor magnus ;
12, vastus externus ; 13, rectus femoris ; 14,
vastus internus ; 15, small part of the biceps
flexor cruris.
The sartorius is covered only by the fascia
lata and the integument. It passes over
the iliacus and rectus femoris muscles, the
femoral vessels, the pectineus, the adductor
longus, adductor magnus, vastus internus,
gracilis, and semitendinosus muscles. The
inner border of this muscle and the most
projecting part of the adductor longus form
the sides, and Poupart's ligament forms the
base, of a triangular space in the upper third
of the thigh, through the middle of which
the femoral artery passes. This frequently
receives the name of Scarpa's triangle.
"The quadriceps extensor cruris, the
extensor muscle of the knee, is divisible
into four parts, one of which, the rectus
femoris, descends from the hip-bone and
remains distinct, w r hile the other three,
distinguished one from the other only
by the arrangement of their fibres, cover
the whole of the anterior and lateral
surfaces of the thigh-bone, from which
they arise.
a. The rectus femoris, extended in
a straight line from the pelvis to the
patella, arises by two tendons, one of
which is attached to the anterior inferior
spinous process of the ilium, and the other, united to the first within an inch
of that point, is attached horizontally in the groove above the upper part of
the brim of the acetabulum. From the prolongation of the tendon so
formed the muscular fibres arise pemiately, and, turning outwards and
QUADRICEPS EXTENSOR CRURIS.
275
backwards as they descend, are inserted in a similar manner into the tendon
below, the superior tendon being prolonged on the anterior, the inferior
tendon on the posterior surface of the muscle. The inferior tendon forms
a broad band inserted into the upper surface of the patella.
Fig. 211.
Fig. 211. DEEP MUSCLES OF THE RIGHT
THIGH IN FRONT.
a, anterior superior, and b, anterior inferior
spinous process of the ilium ; c, outer and
upper part of the great trochanter ; d, sym-
physis pubis ; e, patella ; /, inner side of the
knee-joint and internal lateral ligament ; g, head
of the fibula and outer side of the knee-joint ;
1, front of the gluteus medius ; 2, front of the
gluteus minimus, separate in this case from
the medius ; 3, tendon of the rectus, dividing
above into its two portions, one proceeding
from the inferior spine of the ilium, the other
passing back over the upper border of the ace-
tabulum ; 4, on the lower part of the anterior
intertrochanteric line and at the lower end of
the ilio-femoral part of the capsular ligament,
points by a line to the cut tendon of insertion
of the ilio-psoas muscle ; 5, part of the
obturator externus and quadratus femoris ;
0, pectineus ; 7, part of the adductor brevis ;
8, adductor magnus ; 9, vastus internus ; 10,
crureus ; 11, vastus externus ; 12, tendon of
the rectus ; 13, lower part of the slip of the
fascia lata by which the tensor vaginas femoris
is inserted into the tibia and fibula.
Superiorly this muscle is overlaid by the
tensor vaginae femoris, iliacus, and sartorius
muscles ; further down it is covered only by
fiscia. The acetabutar tendon lies beneath
the gluteus minimus.
6. The vastus externus arises by an
extensive aponeurosis attached to the
base of the great trochanter in front,
and to a ridge on its outer s-l'Ie,
also to the line extending from that
process to the linea aspera, and to the
outer border of the linea aspera itself ;
the aponeurosis is prolonged on the
surface of the muscle and gives origin to
numerous muscular fibres : further it
arises along the line which passes from
the linea aspera to the external condyle
in its upper two-thirds, by means of
muscular fibres attached to the inter-
muscular septum lying between it and
the short head of the biceps. The supe-
rior fibres descend perpendicularly, the
lowest are nearly horizontal, and the
muscle, forming an expanded sheet applied to the surface of the crureus,
is inserted by a broad flat tendon into the tendon of the rectus muscle, the
patella, and the fascia lata on the front and side of the knee-joint.
T 2
276 MUSCLES OF THE LOWER LIMB.
c, d. The vastus internus and crureus consist of different sets of fibres,
which are very closely united. The vastus internus arises from a line which
descends upon the femur at some distance in front of the small trochanter,
and which unites the anterior intertrochanteric line to the inner line
diverging from the linea aspera ; from the lower half of that inner line, and
from the inner lip of the linea aspera ; as well as from the fibrous partition
attached to the line extended between the linea aspera and the inner con-
dyle in connection with the tendon of the adductor magnus. From this
extensive origin, and likewise from the inner surface of the bone, the fibres
proceed downwards and forwards, and terminate on the inner surface of the
patella and knee-joint in a manner similar to those of the vastus externus.
The crureus arises on the anterior and outer surfaces of the femur, reaching
from the line between the trochanters to within a few inches of the patella,
and outwards to the vastus externus. Its fibres are vertical, and are over-
laid inferiorly by an aponeurosis ; and the muscle is inserted by tendon and
fleshy fibres into the upper border and sides of the patella, being in-
separably blended with the insertions of the other parts of the quadriceps
extensor.
The subcrureus is a small band of muscular fibres, which extends from the
lower part of the anterior surface of the femur to the upper part of the
synovial membrane of the knee-joint, on which it ends in scattered fibres.
This little muscle is placed beneath the crureus muscle, and in some cases it is
united with that muscular mass. It is not unfrequently double, or consists of two
separate bundles.
INTERNAL FEMORAL REGION.
(Adductor Muscles.}
The gracilis or adductor gracilis muscle, long and slender, arises by a
thin aponeurosis from the inner margin of the pubic bone, along the lower
half of the symphysis and the upper part of the pubic arch. The lower
tendon, which is at first round, is inserted by a flattened and expanded
portion into the inner side of the tibia, on the same plane with, but
higher than the semitendinosus, and under the expanded tendon of the
sartorius.
This slender muscle is covered by the fascia lata, except in a small part inferiorly,
where it is overlapped by the sartorius ; the deep surface rests against the adductor
brevis, adductor magnus, semimembranosus, and the knee-joint with the internal
lateral ligament. A bursa separates it from that ligament.
The pectineus muscle, flat and nearly quadrangular, arises from the pec-
tineal line, and from the surface of bone in front of it, between the ilio-
pectiueal eminence and the pubic spine. Inclining outwards and backwards
as it descends, it is inserted by a flat tendon into the femur behind the
small trochanter, and into the upper part of the line which connects the
linea aspera of the femur with that prominence.
The pectineus is in contact, by its anterior surface, with the fascia lata and the
femoral vessels ; by the posterior surface, with the obturator vessels and nerve, and
the external obturator and adductor brevis muscles. By the outer border it touches
the psoas magnus ; by the inner border, the adductor longus.
The adductor longus, a flat triangular muscle, internal to the pectinetie,
and lying in the same plane, arises by a short tendon from the body of the
pubes below the crest and near the angle, and is inserted into the inner
ADDUCTOR MUSCLES.
277
margin of the linea aspera in its whole length, between the vastus iu-
teruus and the adductor magnus.
Fig. 212.
Fig. 212. SUPERFICIAL MUSCLES OP
THE INNER SIDE OF THE THIGH,
AND MUSCLES ON THE INNER WALL
OP THE PELVIS.
1, iliacus muscle; 2, part of the
psoas magnus muscle ; 3, obturator
internus, with its fibres converging to-
wards the lesser sciatic foramen ; 4,
pyriformis, with three heads of origin,
and its fibres converging towards the
great sciatic foramen ; 5, a part of the
lumbar aponeurosis covering the erector
spinse muscle ; 6, gluteus maximus ;
7, sartorius, 7', its tendon inserted
below the tuberosity of the tibia ; 8, a
part of the adductor longus ; 9, gracilis,
9', its insertion passing below that of
the sartorius ; 10, part of the adductor
magnus ; 11, semimembranosus ; 12,
semitendinosus, 12', its insertion, and
between 9' and 12' the tendon of the
semimembranosus passing to its in-
sertion in the inner tuberosity of the
tibia.
This muscle is covered by the fascia
lata, the sartorius, and the femoral
vessels; the posterior surface rests
superiorly on the adductor brevis,
and inferiorly on the adductor mag-
nus. Externally it is separated by a
small interval from the pectineus,
and internally it is in apposition with
the gracilis.
The adductor Irevis, thick
above and broad below, arises
by a narrow origin, about two
inches deep, in contact with that
of the gracilis, from the anterior
surface of the body, and the
descending ramus of the pubes ;
directed obliquely backwards and
outwards it is inserted by a
flat tendon into the whole of the
oblique line leading from the
small trochanter of the femur to
the linea aspera, immediately
behind the insertion of the pec-
tineus.
The adductor brevis is concealed at its origin by the adductor longus and at its
insertion in part by the pectineus ; it rests on the adductor magnus, and by its deep
surface is in contact superiorly with the obturator externus.
The adductor magnus muscle arises from a part of the body of the pubes
278 MUSCLES OF THE LOWER LIMB.
external to the lower part of the origin of the adductor brevis, from the
rainl of the pubes and ischium, and from the tuberosity of the ischiura near
the pubic arch. The muscular fibres diverge from their origin, somewhat
like the ribs of a fan from their central pivot ; those from the pubes, shorter
than the resb, pass transversely outwards, and are inserted below the linea
quadrati into the line prolonged from the linea aspera to the great trochanter ;
others pass with increasing degrees of obliquity downwards and outwards, to
be inserted into the whole length of the linea aspera, and into a part of
its internal bifurcation below ; finally, some of the fibres descend almost
vertically, forming the inner border of the muscle, and terminate in a
narrow tendon, which ia inserted into the tuberosity of the inner condyle of
the femur.
Below the level of the inferior bifurcation of the linea aspera, between
the tendinous and fleshy portions of the insertion of the muscle, an interval
is left for the transmission of the femoral vessels backwards into the popliteal
space, and along the femoral attachment the insertion is interrupted by three
or more tendinous arches through which pass the perforating arteries.
This muscle is in contact with the long and short adductors and the vastus internus
in front, with the hamstring muscles and gluteus maxiinus behind, with the gracilis
muscle internally, and with the obturator externus and quadratus femoris muscles
superiorly.
ACTIONS OP THE MUSCLES OF THE HIP AND THIGH.
The gluteus maximus muscle is the chief extensor of the hip-joint. By means of it
the bent thigh is brought into aline with the body; but its most important action, and
that in connection with which it is so largely developed in the human subject, is to
extend the trunk upon the thigh when supported on the ground by the limbs, and in
so doing the muscles of both sides act in combination. The upper part of the muscle
has an abducting, and the lower part an adducting power upon the limb. Although
the full contraction of the glutei maximi is required to bring the body into the erect
posture, it is not necessary for its maintenance, that being effected chiefly by the ten-
sion of certain ligaments and fasciae passing over the joints, and the body in that pos-
ture being so poised that the centre of gravity of the trunk is placed slightly behind
the vertical plane passing through the middle of the hip-joints. The gluteus medius
and minimus are powerful abductors of the thigh, and along with the tensor vaginae
femoris, come principally into action in supporting the body on one limb, which is
done to a certain extent in each step in walking. Their anterior fibres draw forwards
the great trochanter, and rotate the limb inwards, and the more the thigh is flexed
the greater the number of fibres which will exercise this action.
The tensor vagince femoris is generally held to assist the action of the other muscles
by making tense the fascia lata. It likewise aids the preceding muscles in rotating
the limb inwards : its action in this respect is exactly opposed by the upper fibres of
the gluteus maximus, which fibres, together with the tensor vaginae femoris, being con-
tinued into a band of the fascia lata descending to the outer tuberosity of the tibia,
must act as supporters of the thigh at the knee-joint, and are considered by Meyer
(op. cit. p. 222) to act as extensors of the knee.
The pyriformis, obturator internus, and gemelli muscles support the hip-joint poste-
riorly, and rotate the limb outwards. Their greatest contraction is admitted when
the thigh is extended and the toes are directed outwards ; they may be supposed there-
fore to give stability to the erect posture.
The quadratus femoris is partly an adductor and partly a rotator outwards. This
muscle, as well as the pyriformis, obturator internus and gemelli, and obturator
externus, come to be extensors when the thigh is strongly flexed.
The obturator externus has its origin and insertion most approximated when the
thigh is flexed, adducted, and rotated outwards, as is the case in the uppermost of the
two limbs when we cross the knees in sitting. It supports the hip-joint posteriorly
and inferiorly, and is a rotator outwards.
ANTERIOR MUSCLES OF THE LEG. 279
The ilio-psoas muscle, the flexor of the hip-joint, flexes the thigh on the body, or
the body on the thigh, according as either of these is the most fixed.
The pectineus is partly a flexor and partly an adductor.
The adductores magnus, longus, and brevis adduct the thigh, and, along with their
opponents the gluteus medius and minimus, and with the gluteus maximus, balance
the body on the femur in walking.
The adductor muscles and the ilio-psoas t together with t.he pectineus, being all in-
serted at the back part of the femur, tend to rotate the thigh outwards at the same time
that they produce their adducting and flexing actions. The advantage of this prepon-
derance of rotators outwards over rotators inwards becomes apparent by reference to
the movements which take place in walking. When a step is taken, the pelvis is
drawn forwards on that side on which the foot has been advanced, which involves
a considerable rotation of the pelvis outwards at the other hip-joint, by the action of
the muscles of the opposite limb.
The quadriceps extensor femoris extends the knee-joint ; but, as already mentioned
with regard to the gluteus maximus, its action is not requisite for the maintenance of
the erect attitude, the knee-joint remaining in complete extension without muscular
aid while the foot is firmly planted on the ground. This may be tested by the fact
that the patella of a person standing with the knee extended will be found to lie
quite loosely, but will become at once fixed when it is attempted to lift the foot.
The rectus femoris, sartorius, gracilis, semitendinosus, semimembranosus, and
long head of the biceps act on both the hip and knee-joints.
The sartorius produces the flexion of the hip and knee-joints, accompanied by
abduction, which occurs in the posture assumed by the tailor in sitting, and the
muscle derives its name from this circumstance.
The rectus femoris flexes the hip and extends the knee ; it acts wholly from its
anterior head of origin when the thigh is fully extended, and the posterior head is
alone tense when the thigh is bent.
The hamstring muscles extend the hip and flex the knee. It is to be observed,
however, that in the ordinary movements of the body, the hip and knee-joints are
flexed and extended together, and that therefore the joint on which those long muscles
act must be determined by the other muscles which pass over either of those joints
separately.
The gracilis acts as an adductor on the hip-joint. The gracilis, semitendinosus,
and sartorius muscles form the group of rotators inwards at the knee-joint ; they act
along with the popliteus in this respect to greatest advantage in the flexed state of
the knee ; but they likewise favour the commencement of flexion by undoing that
rotation inwards of the femoral condyles on the tibia by which extension of the knee
is completed.
The short head of the biceps is the only flexor of the knee, which passes over that
joint alone. The whole of thia muscle produces external rotation of the leg.
The sulicrureus in extension of the knee-joint probably raises the upper part of the
synovial membrane, and prevents it from being pressed between the patella and
femur.
MUSCLES OF THE LEG AND FOOT.
ANTERIOR REGION.
Between the tibia and fibula, on the front of the leg, are placed four
muscles the tibialis anticus, extensor proprius pollicis, extensor longus
digitorum, and peroneus tertius ; and on the dorsum of the foot one muscle
only arises, the extensor brevis digitorum.
The tibialis anticus arises from the external tuberosity of the tibia, and
about two-thirds of the outer surface of that bone ; from a small portion of
the adjoining interosseous ligament ; from the strong fascia of the leg ; and
from an aponeurotic septum placed between it and the extensor longus
digitorum. The tendon in which all the muscular fibres terminate before
280
MUSCLES OF THE LOWER LIMB.
it reaches the bend of the ankle, glides in a synovial sheath beneath the
anterior annular ligament, and is inserted into the inner and lower part of
the internal cuneiform and the contiguous extremity of the first metatarsal
bone, dividing slightly into two slips as it descends.
Fig. 213. Fi S- 213 - MUSCLES OF THE LOWER LEG AND FOOT
FROM BEFORE.
1 , tendon of the rectus femoris ; 1', ligamentum pa-
tellae ; 2, the lower part of the vastus internus ; 3,
f-M lower part of the vastus externus ; 4, lower part of the
sartorius ; 5, small portion of the fascia lata cut near the
place of its insertion at the knee ; 6, inner head of the
gastrocnemius ; 7, inner part of the soleus ; 8, tibialis
anticus ; 8', its tendon near the insertion ; 9, part of
the extensor longus pollicis; 9', its tendon; 10, ex-
tensor communis digitorum longus ; 10', placed on the
anterior annular ligament over the place of passage of
the four tendons of the extensor communis; 11, pero-
neus longus ; 12, peroneus brevis ; 13, peroneus tertius ;
13', tendon of the peroneus tertius at its insertion ; 14,
origin of the extensor communis digitorum brevis, the
first head of which is seen passing to the great toe near
the line from 9'.
The extensor proprius pollicis placed be-
tween the tibialis anticus and the extensor
longus digitorum, arises from the middle three-
fifths of the anterior narrow part of the inner
surface of the fibula, and from the contiguous
portion of the interosseous ligament for the
same extent. The fleshy fibres run obliquely
forwards into a tendon placed at the anterior
border of the muscle ; and the tendon, after
passing beneath the upper, and through the
lower portion of the annular ligament in a dis-
tinct compartment, and along the dorsum of
the foot, is inserted into the base of the ter-
minal phalanx of the great toe. A delicate
expansion given off from the tendon on each
side spreads over the joint between the meta-
tarsal bone and the first phalanx.
This muscle is partly concealed by those between
which it is placed. It lies external to the anterior
tibial artery in the leg, but crosses in front of that
vessel at the bend of the ankle, and is internal to it
on the foot.
14
13-
The extensor longus digitonvm, pedis, is
situated in contact with the tibialis anticus
above, and between the extensor proprius
pollicis and peroneus tertius below ; it arises
from the external tuberosity of the tibia ;
from the head and the anterior narrowed part of the inner surface of the
fibula in front of the interosseous membrane, for about three fourths of its
length ; from a small part of the iuterosseous ligament at its upper part ;
also from the aponeurotie septa intervening between it and the muscles on
EXTENSOB MUSCLES OF THE TOES.
281
each side, and from the fascia of the leg. The fleshy fibres from this exten-
sive origin pass obliquely into a tendon placed on the anterior part of the
muscle. This subsequently divides into four slips, which descend through
the lower part of the annular ligament, in the same sheath as the peroneus
tertius, and on the dorsum of the foot pass respectively to the four outer
toes. Not ^infrequently the slip belonging to the fifth toe is separated
with that of the peroneus tertius from the rest considerably higher up. The
three inner tendons are each joined at the outer side, on the first phalanx,
by a tendon from the extensor brevis digitorum : all the four tendons
are continued into expansions, which are joined on the first phalanx by
tendinous processes from the luinbricales and interossei muscles, and have
their middle fibres inserted into the second phalanx ; while their lateral
parts unite together and are inserted on the third, in a manner exactly
similar to the arrangement of the extensor tendons on the fingers.
Fig. 214.
Fig. 214. SUPERFICIAL MUSCLES AND TENDONS ON
THE DORSUM OP THE FOOT AND LOWER PART OF
THE LEG ANTERIORLY (after Bourgery). J
a, lower part of the tibia ; &, lower part of the
fibula above the raalleolus extern us ; c, inner side of
the scaphoid bone ; d, internal cuneiform bone ; 1,
lower part of the tibialis anticus muscle ; 1', its tendon
descending in the groove of the internal cuneiform
bone ; 2, extensor longus pollicis ; 2', its expansion
on the dorsum of the great toe ; 3, extensor communis
digitorum dividing into its four tendons for the toes ;
3', the expansion, and 3", the final insertion of the
same upon the second toe ; 4, peroneus tertius ; 4',
its expanded insertion on the base of the fifth meta-
tarsal bone ; 5, small part of the fibres of the soleus
on the inner side of the tibia ; 6, small part of the
peroueus brevis ; 7, extensor brevis digitorum, seen
below the tendons of the extensor longus and peroneus
tertius; 7', 7", on a band of aponeurosis crossing the
toes, the first and fourth tendons of the extensor
brevis muscle passing to join those of the long ex-
tensor ; 8, 9, anterior annular ligament, chiefly in its
luwer part, or ligamentum cruciatum ; between 8 and
c, the inner and lower band enclosing the extensor
loiigus pollicis and tibialis anticus ; below 9, the
outer part of the same enclosing the tendons of the ex-
tensor communis and peroneus tertius ; 10, 11, dorsal
transverse band of the aponeurosis of the foot, uniting
the heads of the metatarsal bones.
The peroneus tertius arises, in continuity
with the lower part of the extensor longus
digitorum, from the lower fourth of the inner
surface of the fibula, from the lower part of
the interosseous membrane, and from an
aponeurosis which connects it on the outer
side with the peroueus brevis. The muscular fibres end in a tendon, which,
after passing through the annular ligament with the long extensor of the
toes, is inserted into the upper surface of the base of the fifth metatarsal
bone, and likewise in some instances into the fourth.
There is often scarcely any line of demarcation between the two preceding muscles.
The peroneus tertius is sometimes as large as the extensor longus digitorum, some-
times its tendon is as large as those of that muscle combined ; it has been observed
to terminate on the fourth metatarsal bone ; and it is sometimes altogether wanting.
282 MUSCLES OF THE LOWER LIMB.
Five tendons are ascribed to the extensor longus digitorum by Cowper (Myot.
Eeform., c. 36, p. Ill), the peroneus tertius having been considered by him as part of
that muscle, a view which is in some degree warranted by the form which it usually
presents.
The extensor brevis digitorum pedis arises from the outer surface of the os
calcis in front of the groove for the peroneus brevis muscle, and from the
lower band of the anterior annular ligament. It divides into four tapering-
slips each of which terminates in a tendon ; the first or most internal of
these, sometimes reckoned as a distinct muscle, is inserted separately into
the dorsal surface of the first phalanx of the great toe near its tarsal
extremity ; and the other three become severally united to the outer border
of the extensor tendons proceeding to the three next toes.
EXTERNAL REGION.
The peroneus longus arises from the head of the fibula, and from more than
the two upper thirds of the external surface of that bone ; from the fascia
of the leg ; and from aponeuroses interposed between it and the contiguous
muscles, viz., the extensor communis digitorum on one side, and the soleus
and flexor longus pollicis on the other. It ends above the ankle in a
tendon, which passes downwards behind that of the peroneus brevis in the
hollow behind the external malleolus, and inclining forwards, turns over the
outer margin of the foot, and enters the excavation on the lower surface of
the cuboid bone, and changing its direction, proceeds inwards and forwards
to be inserted into the lower part of the internal cuneiform and the tarsal
end of the first metatarsal bone : an offset is continued from it to the base
of the second metatarsal bone. In this course the tendon of the peroneus
longus muscle, lying parallel with that of the peroneus brevis, is invested
along with it by a synovial membrane, and bound down by a fibrous band
extended from the end of the fibula to the calcaneum ; on the outer side of
the foot it separates from the peroneus brevis, and in the sole of the foot
the peroneus longus lies in a synovial sheath formed by fibres of the liga-
mentum longum plantte.
The peroneus brevis arises from the two lower thirds of the external
surface of the fibula, internal to the peroneus longus, and from the inter-
muscular septa which dip down in front between it and the extensor longus
digitorum and peroneus tertins, and behind between it and the flexor longus
pollicis. The fibres are directed to a tendon on their outer surface, which
becoming free at the level of the external malleolus, passes behind that
process, sheathed in the same synovial membrane as the tendon of the
peroneus longus, and inclining forwards is inserted into the projection at the
base of the fifth metatarsal bone, having traversed a separate sheath on the
calcaneum, above that for the tendon of the peroueus longus, but lined by
an offset of the same synovial membrane.
POSTERIOR REGION.
The muscles at the back of the leg consist of a superficial group inserted
into the extremity of the calcaneum, and a deeper group covered in by a
deep fascia and descending to the sole.
The superficial group consists of three muscles ; two of them, placed one
on the surface of the other, are of large size, the gastrocnemius and soleus
(extensor tarsi suralis vel extensor magnus, Douglas ; musculus surse,
GASTROCXEMIUS MUSCLE.
283
Soemmerring), form the bulk of the calf of the leg, and are inserted into
the heel by a common tendon the tendo Achillis ; the third, a small muscle,
the plantariSj descends between the other two.
The gastrocnemius muscle arises by two thick tendinous heads from
the condyles of the femur, and ends below in the tendo Achillis. The
Fig. 215. SUPERFICIAL MUSCLES OP THE LEG, SEEN
PROM BEHIND (after Bourgery).
1, lower part of the vastus externus ; 2, tendon of
the biceps flexor cruris, passing to its insertion in the
fibula ; 3, lower part and tendon of the semitendinosus ;
4, lower part of the semimembranosus : its tendon is
seen between 3 and 5 passing to its insertion in the
tibia ; 5, gracilis ; 6, small part of the sartorius ; 7,
outer, and 8, inner head of the gastrocnernius on the
tendinous .part of the calf of the leg ; 9, placed in the
popliteal space, points to the muscular part of the
plantaris ; 9', its thin tendon inside the tendo
Achillis ; 10, the fibres of the soleus descending to
the flat tendon, which, joining with that of the gastro-
cnemius, forms + + the tendo Achillis ; 11, lower part
and tendon of the peroneus longus ; 12, lower fibres
of the peroneus brevis, both passing behind the mal-
leolus externus below ; 13, lower part of the flexor
longus digitorum ; 14, small part of the tendon of
the tibialis posticus, which, alotig with 13, descends
behind the malleolus internus ; 15, is placed near the
lower part of the fibula, and points to the lower
fibres of the flexor longus pollicis, the tendon of
which is seen descending over the tibia at 15'.
outer tendon of origin is attached in an
oblique line to a depression on the outer side
of the external condyle, above the groove for
the popliteus muscle. The inner tendon is
attached in a horizontal line to an impression
above the back part of the internal condyle,
and along with it are fleshy fibres connected
for a short distance with the ridge running
to the linea aspera. The muscular fibres
descending from the two heads remain
separated by a vertical groove on the surface,
but those next the middle meet at an angle
on a tendinous structure below. The fibres
of the superior tendons spread out upon the
surface of the muscle ; the inferior tendon
lies on the deep surface of the muscular mass,
and is continued upwards in a thin aponeu-
rosis with parallel fibres, which glide against
the soleus : between the superficial tendon of
each head and the deep common tendon, the
greater number of the muscular fibres run
obliquely downwards and forwards. The
lower edge of each muscular part presents a convexity downwards; the inner
descending furthest. A synovial membrane, usually communicating with
the knee-joint, lies beneath the inner head of origin, and separates it from
284
MUSCLES OF THE LOWER LIMB.
the tendon of the semimembranosus muscle. A sesamoid fibro-cartilage
is sometimes met with over the outer condyle of the femur, and occasionally
over the inner : it is rarely ossified.
The heads of the gastrocnemius muscle form the inferior boundaries of the
popliteal space, and are placed between the hamstring muscles : the peroneal nerve is
lodged between the external head and the biceps. The gastrocnemius conceals the
popliteus muscle, with the popliteal
p- 216 vessels and internal popliteal nerve
lying on its surface; the plantaris
and soleus are also covered by it.
The short saphenous vein is placed
on its surface, in the interval be-
tween its two parts.
Fig. 216. SUPERFICIAL MUSCLES OP
THE LKQ, SEEN FROM THE INNER
SIDE (after Bourgery). %
1, part of the vastus internus ; 2,
sartorius ; 2', its flat tendon, spread-
ing on the inner upper part of the
tibia; 3, gracilis ; 4, semitendinosus ;
4', its insertion ; and between 2' and
4', that of the gracilis ; 5, semimem-
branosus ; 6, inner head of the gastro-
cnemius ; 7, soleus ; 8, 8', placed
upon the tendo Achillis, point to the
small tendon of the plautaris descend-
ing on the inner side ; 9, small part
of the tendon of the tibialis posticus ;
10, flexor communis digitorum ; 11,
points to a portion of the flexor longus
pollicis, sunk in shadow; 12, a nar-
row part of the tibialis anticus ; 12',
on the internal cuneiform bone, above
the divided tendon of insertion of the
tibialis anticus ; 13, abductor pollicis ;
there are also shown in this part of the
figure the connection of the abductor
posteriorly with the internal annular
ligament and os calcis, and the manner
in which the internal annular liga-
ment forms a retinaculum for the
tendons of the muscles of the leg as
they descend.
The soleus muscle arises ex-
ternally from the posterior part
of the head of the fibula, and
from the surface beneath it for
a third of the length of the
bone; internally from the ob-
lique line which gives insertion
to the popliteus, and from the
posterior edge of the tibia about
three inches below that line;
also in the space intermediate between the tibia and fibula, from a ten-
dinous band extended from one bone to the other over the posterior tibial
vessels and nerve. Inferiorly, the muscular fibres descend upon the tendo
TEXDO ACHILLIS. PLANTARIS. 28-5
Achillis considerably further than those of the gastrocnemius. The posterior
surface presents a thin covering of longitudinal aponeurotic fibres continued
up from the tendon below, and gliding on the similar tendinous surface of
the gastrocnemius muscle. On the deep surface the edges of two mem-
branous tendons, the other edges of which look towards the middle line of
the muscle, imbedded in its substance, are seen descending from the tibial
and fibular origins : the fibres from the deep aspects of those tendons are
directed obliquely inwards to a tendinous septum which divides the muscle
into lateral halves ; while those from their superficial aspects pass with
similar obliquity to the flat tendon on the surface of the muscle, the fibres
placed at the sides forming the lateral borders and part of the deep surface
of the muscle. Thus the soleus is composed entirely of short oblique fibres
of from one to two inches in length.
The soleus rests upon the flexor longus pollicis, flexor longus digitorum, and tibialis
posticus muscles, together with the posterior tibial vessels and nerve, from which,
however, it is separated by the deep aponeurosis.
The Undo Achillis, the thickest and strongest tendon in the body, is
formed by the union of the flat tendon of the gastrocnemius with the
thicker and more rounded tendon of the soleus. It is from three to four
inches long below the point where the muscular fibres of the soleus cease to
be attached to it. It is inserted inferiorly into the back part of the
tuberosity of the os calcis. Between the upper part of the tuberosity of the
os calcis and the tendon a synovial bursa is interposed.
The gastrocnemius is, in some cases, joined by a bundle of muscular fibres, which
arises separately from the femur above one of the condyles. This bundle has been
observed passing between the popliteal artery and vein (R. Quain, op. cit. plate 80,
figs. 4 and 5). To the soleus an accessory portion is occasionally added at its lower
and inner part; this usually ends on the inner side of the tendo Achillis, but it
sometimes forms a tendon, attached separately to the os calcia.
The plantaris arises from the femur immediately above the external con-
dyle, and from the posterior ligament of the knee-joint, where this is covered
by the corresponding head of the gastrocnemius ; its muscular part is from
three to four inches in length, and terminates in a long delicate tendon,
which inclines inwards between the gastrocnemius and soleus, and, running
along the inner border of the tendo Achillis, is inserted conjointly with it
into the posterior part of the calcaneum.
The designation by which this little muscle is known was assigned to it when the
tendon was believed to terminate in the plantar fascia, as the palmaris longus does in
the fascia of the hand. It was so described by Galen ; and, though the real manner
of termination was correctly pointed out by Vesalius (Oper. 1, 2, p. 419), the error
was continued through many succeeding works, and is to be found even in Cowper's
"Myotomia Reformata" (p. 105).
The plantaris varies in its mode of termination ; it is sometimes enclosed in the
lower part of the tendo Achillis ; and, in other cases, it ends in the internal annular
ligament, which binds down the tendons and vessels behind the inner malleolus.
The deep group of posterior muscles of the leg is in close contact with
the bones ; it consists of the popliteus, flexor longus digitorum, flexor longus
pollicis, and tibialis posticus.
The popliteus, an oblique muscle placed below the knee, arises by a thick
tendon, about an inch in length, from the fore part of the popliteal groove
on the outer side of the external coudyle of the femur, within the external
286
MUSCLES OF THE LOWER LIMB.
lateral ligament and capsule of the knee-joint ; it is in contact with the
external semilunar cartilage, and receives additional fibres from the posterior
ligament of the joint. The muscular fibres diverge as they pass downwards,
Pig 217 Fig- 217. DEEP POSTERIOR MUSCLES OP THE
LEG. i
a, popliteal surface of the femur ; 6, bare surface
of the upper fourth of the fibula, from which the
soleus muscle has been removed ; c, malleolus in-
ternus; d, malleolus externus; e, tuberosity of the os
calcis, with the tendo Achillis inserted into it, and the
plantaris on its inner side; 1, inner head of the gastro-
cnemius cut short at its origin ; 2, outer head ; 3,
plantaris; 4, tendon of the semimembrauosus muscle
near its insertion, seen spreading in three portions,
viz., to the inside of the tibia, towards the popliteal
fascia, and towards the ligamentum posticum ; 5,
tendon of the biceps inserted into the head of the
fibula ; 6, popliteus muscle ; 7, upper part of the
origin of the soleus from the fibula, cut short ; 7', line
of its tibial origin ; between these figures is seen the
perforation in the upper part of the interosseous
membrane; 8, tibialis posticus; 8', its tendon, pass-
ing between the flexor digitorum coinmunis and the
tibia ; 9, flexor digitorum communis ; 9', its tendon,
with that of the tibialis posticus, passing behind the
malleolus internus ; 10, flexor longus pollicis ; 10',
placed beside its tendon, where it passes over the
tibia and astragalus ; 11, peroneus longus ; 11', its
tendon behind that of the peroneus brevis, passing
down behind the malleolus externus ; 12, peroneus
brevis.
and are inserted into all that triangular sur-
face of the tibia which is above the posterior
oblique line.
The tendon of the popliteus muscle
occupies the groove on the femur in flexion
only.
The popliteus is bound down by an aponeurosis,
principally derived from the tendon of the semi-
membranosus muscle. The popliteal vessels and
internal popliteal nerve lie upon its posterior
surface, and it is covered by the gastrocnemius
muscle.
L
The three remaining muscles of this group
are bound down together by a deep fascia,
which extends between the tibia and fibula,
and separates them from the soleus.
The flexor longus digitorum pedis, or flexor
perforans, arises from the posterior surface
of the tibia, in the space below the oblique
line, and as far down as within three inches of
the inner ankle ; it likewise arises by aponeu-
rotic fibres connected with the flexor longus
pollicis, which pass over the surface of the
tibialis posticus. The fleshy fibres pass obliquely backwards into a tendon
FLEXOR ACCESSORIUS. LUMBRICALES.
287
at the posterior aspect of the muscle. The tendon descends in the groove
behind the internal malleolus, superficial to the tibialis posticus, and invested
by a distinct fibrous and synovial sheath ; it is then directed under the
arch of the os calcis, obliquely forwards and outwards, into the sole of
the foot, where it crosses below the tendon of the flexor longus pollicis,
and is connected with it by a tendiuous slip ; it then divides into four
parts, which pass forwards to be inserted into the terminal phalanges
of the four smaller toes. Each digital tendon enters a fibrous sheath on
the toe for which it is destined, perforates the corresponding tendon of the
flexor brevis digitorum, and is invested with synovial membrane, and con-
nected by vincula accessoria to the phalanges ; the whole arrangement being
exactly similar to that which has been already described as occurring in the
fingers.
The posterior tibial vessels lie upon the surface of the flexor longus digitorum.
Intimately connected with the tendon of the flexor longus digitorum are
the flexor accessorius and the lumbricales muscles, which, although they
occupy the foot, may be most conveniently described in this place.
The flexor accessorius (moles carnea Sylvius) arises by two heads, the
internal and larger of which is fleshy, and is attached to the inner surface
of the calcaneum, while the external, flat, narrow, and tendinous, is attached
to the plantar surface of the calcaneum a little in front of the external
tubercle, and to the ligamentum longum plantse. Those origins united form
a muscular mass which is inserted into the external border and upper and
lower surfaces of the tendon of the flexor longus digitorum.
Fig. 218. MIDDLE LATER OP THE PLANTAR MUSCLES OP THE
FOOT, TOGETHER WITH THE TENDONS OP THE LoNQ FLEXOUS
AND THE ACCESSORIUS AND LUMBRICALES MUSCLES.
1, tendon of the flexor longus pollicis muscle, emerging
behind from its sheath below the sustentaculuin tali, and
passing deeper than, 2, the tendons of the deep common flexor ;
3, two heads of the flexor accessorius ; 4, the four lumbricales ;
5, tendon of the flexor brevis cut short and left on the second
toe, seen splitting to allow the passage through it of the tendon
of the long flexor ; 6, flexor brevis pollicis ; 7, flexor brevis
minimi digiti ; there is also represented on the outer side of
the foot the tendon of the peroueus longus winding round the
cuboid bone, to pass across the foot in its groove, where it is
concealed by the accessorius and other muscles. 7
The lumbricales muscles, four in number, arise from
the tendons of the flexor longus digitorum at their
point of division, each being, with the exception of
the most internal, attached to two tendons, and pass
forward to the inner sides of the four outer toes ; each
muscle ends in a tendon, which is united with the ba c e
of the first phalanx, and is inserted into the expansion
of the extensor tendon on the dorsum of the toe.
Fig. 218.
They
The lumbricales of the foot are less fully developed than those of the hand,
are liable to the same variations.
In the sole of the foot the tendon of the flexor longus digitorum, together with the
flexor accessorius and lumbricales, is covered below by the flexor brevis digitorum ;
the plantar nerves and hinder part of the external plantar artery being placed
288
MUSCLES OF THE LOWER LIMB.
between them. This divided tendon, with its additional muscles, conceals the
adductor pollicis, the tendon of the flexor longus pollicis, the transversus pedis, the
interossei muscles, and the plantar arterial arch.
The flexor longus pollicis pedis arises from the two in ferior thirds of the
posterior surface of the fibula, except for an inch at ! ts lowest part ; from
the intermuscular septum interposed between it and the peronei ; and from
the aponeurosis common to it and the flexor longus digitorum, and which
covers the tibialis posticus.
The muscular fibres, passing obliquely backwards and downwards, end
in a tendon on their posterior surface. This tendon traverses a groove
behind the tibia, and another at the back of the astragalus, being bound
down to those bones by fibrous and synovial sheaths. Thence passing
forwards below the sustentaculum tali, it is connected, in the sole of the
foot, by a tendinous slip, with the tendon of the flexor lougus digitorum,
by which it is crossed, and proceeds in a fibrous sheath over the first
phalanx of the great toe to be inserted into the base of the terminal
phalanx.
Below the ankle the tendon of this muscle is separated from those of the tibialis
posticus and flexor longus digitorum by an interval of more than half an inch, in
which are placed the posterior tibial vessels and nerves.
The tibialis posticus muscle, placed between the two long flexor muscles,
arises from the whole interossecus membrane except for two inches at the
lower end, and from the adjacent surfaces of the tibia and fibula, the tibial
attachment extending from the superior tibio-fibular articulation to a point
at a lower level than that of the flexor longus digitorum, and the attach-
ment to the fibula extending along the three middle fifths of that bone ; it
also arises from the aponeurosis derived from the adjacent muscles, which
covers it. The muscular fibres end in a strong flat tendon, which, passing
between the tibia and the long flexor of the toes, turns forwards in a groove
beneath the internal malleolus, and is inserted into the tuberosity of the
scaphoid bone.
Fig. 219. Fig. 219. TRANSVERSE SECTION OF THE EIGHT
FOOT BETWEEN THE TARSDS AND METATARSUS,
SHOWING THE TENDINOUS AND APONEUROTIO
STRUCTURES FROM THE FRONT, i
This figure is also designed to show the trans-
verse arch formed by the three cuneiform and the
cuboid bones, a, articular surface of the internal
cuneiform bone for the first metatarsal ; 6, the
middle cuneiform ; c, the external cuneiform ; d and
e, the surfaces of the cuboid bone for the fourth and
fifth metatarsal bones ; between these bones are
seen the strong interosseous and plantar ligaments
which bind them together ; 1, slip of the tendon of
the tibialis anticus, which passes on to its insertion
in the first metatarsal bone ; 2, tendon of the
extensor longus pollicis ; 3, slip of the extensor brevis digitorura to the great toe ;
3', remainder of the extensor brevis digitorum ; 4, four slips of the extensor communis
digitorum longus ; 5, peroneus tertius ; 6, peroneus brevis ; 7, peroneus longus cut
obliquely where it is emerging from the sheath below the cuboid bone ; beside 7, the
space between the cuneiform bones and the subjacent fasciae and tendons is occupied by
loose fatty tissue ; 8, tendon of the flexor longus pollicis ; 9, tendon of the flexor com-
munis digitorum longus, with the slip of union from the flexor pollicis; 10, flexor
accessorius ; 11, fleshy part of the abductor pollicis ; 12, flexor brevis digitorum ;
13, abductor minimi digiti.
SUPERFICIAL PLANTAR MUSCLES.
289
From the insertion, offsets of the tendon are prolonged forwards to all
the cuneiform bones, to the os cuboides, and to the bases of the second,
third, and fourth metatarsal bones ; and one thin process is directed back
to the sustentaculum tali. The tendon is covered by a synovial membrane
behind the malleolus. Close to its insertion, where it lies against the astra-
galus, it contains a sesamoid nbro-cartilage, which is occasionally converted
into bone.
The tibialis posticus is concealed in great part by the aponeurosis prolonged over
it from the muscles on either side. Superiorly it is not covered by these muscles,
and supports the posterior tibial and peroneal vessels.
SHORT PLANTAR MUSCLES.
COMMON FLEXOR OF THE TOES. The flexor brevis digitorum, or flexor
perforatusj arises by a small pointed and tendinous attachment from the
inner part of the greater tuberosity of the calcaneum, from the deep sur-
face of the plantar fascia for about two inches forwards, and from the
intermuscular septum on each side. The muscle terminates in four slender
tendons, inserted into the second phalanx of each of the four outer toes.
Each tendon prior to its insertion divides and gives passage between its
parts to the tendon of the long flexor, in a manner precisely similar to the
arrangement of the tendons of the flexor sublimis and flexor profundus
muscles of the hand.
This muscle lies between the abductor pollicis and abductor minimi digiti, and is
covered by the plantar fascia, which adheres very closely to the posterior part of its
surface, and gives origin there to some of its fibres ; it conceals the flexor accessorius,
with the tendons of the flexor longus digitorum, the lumbricales, and the plantar
vessels and nerves.
Fig. 220. SUPERFICIAL PLANTAR MUSCLES, AS SEEN ON THE Fi g< 220.
REMOVAL OF THE PLANTAR FASCIA. ~
1, abductor pollicis; 2, flexor brevis digitorum dividing into
four slips for the lesser toes : in the second, the sheath is
opened so as to show the tendon of the flexor brevis perforated
hy that of the flexor longus ; in the other three toes the trans-
verse and oblique crossing fibres of the sheath are shown ; 3,
strongest portion of the plantar aponeurosis left upon the
surface of the flexor brevis, near the os calcis ; 4, abductor
minimi digiti : the lumbricales muscles are also in part
shown.
MUSCLES OF THE GREAT TOE. The abductor
pollicis pedis arises from the inner part of the larger
protuberance of the calcaneum, from the internal
annular ligament and the tendinous and fibrous struc-
tures on the inner border of the foot as far forwards
as the internal cuneiform bone, from the septum
between it and the flexor brevis digitorum, and from
the plantar fascia covering it. The fleshy fibres end
in a tendon, which, after uniting with the internal
head of the flexor brevis pollicis, is inserted into the
inner border of the base of the first phalanx of the
great toe.
The flexor brevis pollicis pedis, single and pointed behind, but divided into
u
290
MUSCLES OF THE LOWER LIMB.
two parts or heads in front, arises by a flat tendinous process, which extends
along a great part of its upper surface, from the inner border of the cuboid
bone, and from the tendinous band sent to the cuneiform bones from the
tendon of the tibialis posticus. The heads into which the muscular mass
divides are intimately connected each with one of the sesamoid bones of the
first metatarso-phalangeal articulation, and are inserted, one into the inner
border of the base of the first phalanx in union with the abductor pollicis,
the other into the outer border in union with the adductor.
The tendon of the flexor longus pollicis runs in the interval between the heads of
the short flexor.
The adductor pollicis pedis, placed obliquely in the sole of the foot, and
forming a thick fleshy mass, arises from the tarsal extremities of the third
and fourth metatarsal bones, and from the sheath of the peroneus longus
muscle ; narrowing as it passes forwards, it is inserted, conjointly with the
external head of the flexor brevis pollicis, into the base of the first phalanx
of the great toe.
The transversus pedis consists of a series of narrow fasciculi of fleshy
fibres, placed transversely under cover of the flexor tendons, and arising,
beneath the heads of the second, third, and fourth metatarsal bones, from
the ligaments connecting those bones with the phalanges. Its outer ex-
tremity is attached usually to the lateral ligament connecting the fifth
metatarsal bone with the first phalanx of the little toe ; but it often
commences only at the fourth. The fibres of the muscle pass transversely
inwards, and are inserted in union with the adductor pollicis into the first
phalanx of the great toe.
Fig. 221.
Fig. 221. DEEPER PLANTAR MUSCLES, AS SEEN AFTER THE
REMOVAL OP THE LONG FLEXOR TENDONS AND THE ACCES-
SORY AND LUMBRICALES MUSCLES.
1, flexor brevis pollicis ; 2, adductor pollicis ; 3, transversus
pedis ; 4, flexor brevis minimi digiti ; 5, 5, part of the third
and fourth dorsal interossei ; 6, 6, the second and third plantar
interossei ; 7, tendon of the peroneus longus passing round
the cuboid bone to enter its groove ; 8, long plantar ligament
passing forwards to the ridge of the cuboid bones and spreading
over the groove of the peroneus tendon : in the upper part of
the figure, on the inner side, the opened sheaths of the flexor
longus pollicis and flexor longus digitorum are shown.
MUSCLES OF THE LITTLE TOE. The abductor
minimi digiti has a wide origin behind, from the
front of both tubercles on the under surface of the
os calcis, from the external intermuscular septum,
and from the upper surface of the process of the
plantar fascia which extends from the external
tubercle to the base of the fifth metatarsal bone.
The fleshy fibres end in a tendon, which, after sliding
along a smooth impression on the inferior surface
of the base of the fifth metatarsal bone, is inserted
into the external surface of the base of the first
phalanx of the little toe.
This muscle is covered by the plantar fascia. Its deep surface is in contact with
INTEBOSSEI MUSCLES.
291
the external head of the flexor accessorius, the ligamentum longum plantse, the
peroneus longus, and the flexor brevis minimi digiti.
The flexor brevis minimi digiti arises by tendinous fibres from the base of
the fifth metatarsal bone, and from the sheath of the peroneus longus, and
terminates in a tendon which is inserted into the base and external border
of the first phalanx of the little toe. It is covered partly by the abductor
minimi digiti, partly by the plantar fascia.
THE INTEROSSEOUS MUSCLES of the foot, like those of the hand, are seven
in number, three plantar and four dorsal ; the plantar iuterossei, visible
only from the under side, arise each from only one metatarsal bone, and
their action is to approximate the toes ; the dorsal muscles, visible both from
above and below, arise each from two metatarsal bones, and in their action
separate the toes. The arrangement of the second dorsal and first plantar
interosseous muscles of the foot, in relation to the toes, is somewhat different
from that of the corresponding muscles of the hand.
Fig. 222, A. DEEP DISSECTION OP THE Fig. 222.
DORSUM OF THE FOOT, TO SHOW THE A g
DORSAL INTEROSSEOUS MUSCLES. \
1, 2, 3, 4, the several dorsal inter-
osseous muscles : the final insertion of
the extensor tendons into the phalanges of
the toes is also shown in this figure, more
particularly in the great toe, and the sepa-
rate insertion of the tendons of the short
and the long extensor.
B. DEEP DISSECTION OF THE SOLE OF
I'HE FOOT, TO SHOW THB PLANTAR
INTEROSSEOUS MUSCLES. .
1, 2, 3, the three plantar interossu ;
this figure also shows the long and short
plantar ligaments, and the insertion of the
tendon of the peroneus longus muscle into
the first metatarsal Lone.
The dorsal interossei are arranged
so as to separate the toes from the
line in which the second toe rests ;
they lie one in each interspace, their
fibres radiating pennately from a
central tendon ; and they terminate
partly in the first phalanx and partly
in the extensor aponeurosis of the toe to which each belongs. The first
two are inserted one on each side of the second toe ; the third and fourth
are inserted on the outer sides of the third and fourth toes.
The plantar interossei, arranged so as to approximate the three outer toes
to the second, arise from the inner and under surfaces of the third, fourth,
and fifth metatarsal bones, and are inserted in a manner similar to the dorsal
interossei into the inner sides of the first phalanges of the third, fourth,
and fifth toes.
ACTIONS OF THE MUSCLES OF THE LEG AND FOOT. There is only one muscle of the
leg, viz., the popliteus, which acts on the knee-joint alone. Its principal action is
that of a rotator inwards of the lower leg ; and it is interesting to observe that while
rotation of the leg at the knee-joint occurs only in flexion, it is in that position only
that the tendon of the popliteus lies in its groove on the femur.
292 MUSCLES AND FASCIAE OF THE LOWER LIMB.
The gastrocnemius muscle acts both as a flexor of the knee and as an extensor of
the foot. When the anterior muscles of the leg fix the ankle-joint, it is fitted to act
as a flexor of the knee ; when the knee is fixed either by being placed in complete
extension or by the sustained action of the extensor muscles, the gastrocnemius acts
entirely on the foot, and combines with the soleus in extending the ankle and astragalo-
calcaneal joints. By the complete contraction of these muscles the heel is lifted from
the ground and the body is raised on the toes. In leaping, as the limb is suddenly
straightened by extension both at the knee and ankle joints, the gastrocnemius acts in
the most advantageous manner possible on the foot, seeing that by the movement of
the knee its fibres are kept stretched.
The tibialis anticus muscle flexes the foot upon the leg and raises its inner side :
the peroneus tertius flexes the foot and raises its outer side : the tibialis posticus
extends the foot and gives it an inward direction : the peroneus longus and brevis
extend the foot and give it an outward direction. The peroneus longus, in crossing
the foot inferiorly, strengthens the transverse arch formed by the metatarsal bones and
anterior range of tarsal bones ; especially when that arch is pressed upon by the
weight of the body falling on the balls of the toes, as in stooping with bended knees.
The/exor and extensor muscles of the toes, including the lumbricales, act like the
corresponding muscles in the hand. The direction of the flexor longus digitorum is,
however, modified by the flexor accessorius, so as to bring its line of action into the
direction of the middle of the foot and of the short flexor. The flexor accessorius and
tendon of the foot and of the long flexor likewise assist the short flexor and the plantar
aponeurosis in maintaining the arch of the foot.
FASCIAE OF THE LOWER LIMB.
The superficial fascia of the lower limb is similar to that of other parts of
the body. The subcutaneous layer is continuous with that of the lower
part of the abdomen. The disposition of the deeper and more membranous
part on the front of the thigh deserves attention in respect that it is so firmly
attached to Poupart's ligament as to prevent the passage of fluids under it,
from the thigh to the abdomen.
The aponeurosis of the lower limb, or fascia lata, is similar to the aponeu-
rosis of the upper limb, but in some parts much stronger.
In the gluteal region it is attached to the crest of the ilium, and descends
as a strong membrane on the surface of the gluteus medius, as far as the
upper margin of the gluteus maximus muscle ; it there divides into two
layers, one superficial to the gluteus maximus, a continuous sheet, attached
at its inner end to the sacrum, the other on the deep surface of that muscle.
These two layers incase the muscle, and again unite at its inferior margin.
On the thigh the fascia lata forms a continuous sheath, varying in thick-
ness in different parts. It is strongest on the outer aspect of the limb,
where its dense and glistening parallel fibres give it much the appearance of
a tendinous aponeurosis, and where it serves the purpose of a tendon to the
tensor vaginse femori?, and to a large part of the gluteus maximus. It is
thinnest in the upper and inner part of the thigh, where it covers the
adductor muscles. Near the knee it is considerably strengthened by ten-
dinous expansions given off from the lower termination of the extensor and
flexor muscles of the knee-joint.
In front of the thigh, a little below and external to the inner end of
Poupart's ligament, is placed the saphenous opening, an aperture in the
fascia lata through which the internal saphenous vein passes to join the
femoral vein, and which receives special attention from its being the place
of exit of femoral hernia. The outer part of this opening extends to the
femoral artery, and is bounded externally by a crcscentic margin, the fal-
FASCIA LATA. FEMORAL SHEATH. 293
ciform process, which crosses the surface of the infundibuliform sheath of the
femoral vessels. This margin in the middle of its extent is continued into
looser tissue, but superiorly and inferiorly it ends in two more distinct
incurved extremities, the superior and inferior cornua. The inferior cornu,
the most completely defined part of the margin, lies in the angle between
the internal saphenous and the femoral vein, below their junction; while
the superior cornu forms a larger curve, and is bound down to the fascia of
the thigh a little below and in front of Gimbernat's ligament.
It is customary to call the parts of the fascia lata which are placed
external and internal to the saphenous opening the iliac and pubic portions.
The iliac portion is intimately connected above with Poupart's ligament,
as well as with the fascia transversalis and deep layer of the superficial
fascia of the abdomen, and internally forms the falciform margin of the
saphenous opening; the pubic portion, attached superiorly to the pectineal
line, passes on its outer side deeply behind the sheath of the vessels, with
which it is connected, and is continued into the fasciae between the muscles.
In the natural state, the saphenous opening is filled up by the cribriform
fascia, a thin and somewhat irregular membrane which is continuous exter-
nally with the falciform margin of the opening, and is attached internally
to the surface of the pubic portion of the fascia lata : it receives its name
from being perforated by numerous small blood-vessels and by the superficial
lymphatics of the thigh as they pass in to join the deep group.
The fascia lata of the thigh has various deep processes. One of these,
leaving the main fascia at the insertion of the tensor vaginae femoris muscle,
passes upwards within that muscle as a strong flat band on the surface of
the vastus externus, and is attached superiorly round the origin of the rectus
femoris, and to the tendinous arch at the insertion of the gluteus minimus
muscle. Two processes, the external and internal intermuscular septa, bind
the fascia to the femur in the lower part of the thigh : the external septum,
situated between the vastus externus muscle and the short head of the biceps,
is inserted into the liuea aspera from the lower border of the tendon of the
gluteus maximus to the outer condyle of the bone : the internal septum,
much thinner, is inserted into the femur between the vastus internus and
the adductor muscles.
Sheaths of the Femoral Vessels. The femoral vessels are surrounded by an
investment of fascia, which in its upper part is particularly distinct, and
receives the name of the crural sheath. This sheath, commencing at the
deep crural arch, is continuous with the fascia transversalis and fascia iliaca.
Its outer border descends in contact with the artery, while its inner border
is inclined outwards from the margin of Gimbernat's ligament, and comes in
contact with the vein at the distance of less than an inch lower down :
the sheath is therefore funnel-shaped. It is divided into three compart-
ments, separated by thin septa : the outermost contains the artery, the
middle one the vein, and the innermost forms a space the upper end of
which corresponds to the crural ring, and which is occupied by a lymphatic
gland and some fat ; this compartment is interesting to the surgeon as being
the passage by which femoral hernia descends, and on this account has been
named the crural canal.
Extending upwards from the opening for the femoral vessels in the
adductor magnus muscle, is an aponeurotic membrane which consists of trans-
verse fibres passing from the surface of the vastus internus to the adductor
magnus and adductor longus muscles. It becomes thinner as it ascends,
and it encloses between the muscles named a passage sometimes called
29 i
FASCIAE OF THE LOWER LIMB.
Hunter's canal, which contains the femoral artery and vein, together with
the internal saphenous nerve.
The aponeurosis of the leg is particularly dense in the upper and fore
part, and is strengthened by fibres from the tendons of the biceps externally,
and the sartorius, gracilis, and semimembranosus internally. Behind, over
the popliteal space, it consists of strong transverse fibres, which bind
togethtr the muscles of the outer and inner sides, and is perforated at the
lower part of the space by the external saphenous vein ; lower down it becomes
much thinner over the gastrocnemius muscle. This fascia is adherent to
the periosteum covering the head, the spine and the posterior margin of the
tibia, the head of the fibula, and the outer and inner malleoli ; and it invests
the leg completely except at the inner surface of the tibia. From its
deep surface intermuscular septa are prolonged inwards. The situation of
these septa is marked on the surface of the fascia by several white lines in
front and on the outer side of the leg. One, parallel to the spine of the
tibia, runs between the tibialis anticus and the extensor longus digitorum,
and is attached deeply to the interosseous membrane ; and another extending
Fig. 223.
-5
Fig. 223. SUPERFICIAL MUSCLES AND TENDONS ON
THE DORSUM OP THE FcOT AND LOWER PART OF
THE LEO ANTERIORLY (after Bourgery).
a, lower part of the tibia ; b, lower part of the
fibula above the malleolus externus ; c, inner side of
the scaphoid bone ; d, internal cuneifurm bone ; 1,
lower part of the tibialis anticus muscle ; 1', its
tendon descending in the groove of the internal cunei-
form bone ; 2, extensor longus pollicis ; 2', its expan-
sion on the dorsum of the great toe ; 3, extensor
communis digitorum dividing into its four tendons for
the toes ; 3', the expansion, and 3", the final inser-
tion of the same upon the second toe ; 4, peroneus
tertius ; 4', its expanded insertion on the base of the
filth metatarsal bone ; 5, small part of the fibres of
the soleus on the inner side of the tibia ; 6, small
part of the peroneus brevis ; 7, extensor brevis digi-
torum, seen below the tendons of the extensor longua
and peroneus tertius ; 7'-, 7", on a band of aponeu-
rosis crossing the toes, the first and fourth tendons of
the extensor brevis muscle passing to join those of the
long extensor ; 8, 9, anterior annular ligament,
chiefly in its lower part or ligamentum cruciatum ;
between 8 and c, the inner and lower band enclosing
the extensor longus pollicis and tibialis anticus ;
below 9, the outer part of the same enclosing the
tendons of the extensor communis and peroneus
tertius ; 10, 11, dorsal transverse band of the aponeu-
rosis of the foot, uniting the heads of the inetatarsal
bones.
between the long extensor and peroneus
tertius in front, and the peroneus longua
and brevis behind, is inserted along the
anterior margin of the shaft of the fibula.
These septa, as well as the upper and anterior portion of the fascia itself,
afford attachment to the muscular fibres, and thus increase greatly the
extent of the surfaces from which the muscles derive their origin.
Between the superficial and the deep muscles on the back of the leg, a
ANNULAR LIGAMENTS OF THE ANKLE. 295
layer of fascia is stretched from side to side across the limb known as the
deep fascia of the leg. Where covered by the solens and gastrocnemius,
this fascia is weak, but it becomes stronger as it escapes from under cover
of those muscles and approaches the malleoli.
Below the ankle the fascia of the leg becomes continuous with that of
the foot. In front, and on the sides of that joint, it is strengthened by
broad bands of fibres, which are called annular ligaments. These bands
being merely stronger portions of the ordinary fascia, it is often difficult
in dissection to mark satisfactorily the exact line of their upper and lower
margins. They serve as retinacula, confining the tendons in their natural
positions.
The anterior annular ligament includes two structures, one placed on the
lower part of the leg, the other opposite the bend of the ankle. The upper
band, ligamentum transversum cruris (Henle), of considerable breadth,
stretches from the lower end of the fibula to the lower end of the tibia, and
binds down the vertical portion of the extensor tendons as they turn forwards
to the foot : the sheath for the tendon of the tibialis anticus is distinct from
the others. The lower band., ligamentum cruciatum cruris (Henle), presents
superficially the appearance of the letter Y placed upon its side, being single
in its outer half, and usually divided into two branches internally. The
outer portion consists of a strong loop of fibres arising from the fore part of
the os calcis, completely surrounding the peroneus tertius and extensor
longus digitorum muscles, and inserted into the fore part of the os calcis,
deep in the hollow between that bone and the astragalus. Less regular is
the arrangement of the bands which pass from the extremity of the loop to
the inside of the foot : the strongest and most constant band passes super-
ficial to the extensor pollicis and on the deep surface of the tibialis anticus
muscle, only a few fibres passing superficial to the latter ; while another
band, lower down, is inserted into the inner side of the foot, in front of the
ankle, after crossing both those tendons.
The loop formed by the outer part of this ligament derives additional interest from
being present in the lower animals, as may be well seen in the dog or cat, and in the
horse.
The internal annular ligament crosses the space between the inner ankle
and the heel, through which the tendons of the flexor muscles run. Its
upper border, continuous with the fascia of the leg (more especially the
deep layer), is very imperfectly defined ; and its lower border, giving
origin to many fibres of the abductor pollicis, is but little more distinct.
Its anterior extremity is attached to the inner malleolus, and its posterior
termination is inserted into the inner margin of the calcaneum ; but between
these two points it arches over several osseous grooves so as to form canals
for the passage of tendons. The first canal (next the malleolus) contains
the tendon of the tibialis posticus, and the second that of the flexor longus
digitorum, each being provided with a synovial lining. Then follows a
wider space for the passage of the posterior tibial vessels and nerve. Lastly,
a fourth canal upon the astragalus, lined like the first two by a synovial
bursa, transmits the tendon of the flexor longus pollicis.
The external annular ligament extends from the point of the outer mal-
leolus to the outer surface of the calcaneum, and keeps in place the tendons
of the long and short peronei muscles. The tendons are close together,
and are surrounded by one synovial sac.
296 FASCIA OF THE LOWER LIMB.
The fascia on the dorsum of the foot is reduced to a thin membrane pro-
longed from the anterior annular ligament over the extensor tendons.
Beneath it, deep fasciae are placed over the short extensor of the toes and
the interossei muscles.
The plantar fascia is stronger and thicker than any other of the fibrous
membranes. It is composed of dense, white, glistening fibres, the greater
number of which are ranged in a longitudinal direction, and extend
from the under surface of the os calcis forwards to the heads of the meta-
tarsal bones. It presents a central and two lateral portions, clearly
marked off from each other by two strong internmscular septa, indicated
on the surface by grooves. The inner portion, very thin and unlike the
others, invests the abductor pollicis, and is often partly removed with the
skin in dissection. It is continuous round the inner border of the foot
with the dorsal fascia and with the internal annular ligament. The outer
part covers the abductor minimi digiti, and is much stronger, particularly
between the outer tubercle of the calcaneum and the base of the fifth
metatarsal bone, between which points it forms a strong ligament. It is
continuous round the outer border of the foot with the dorsal fascia, and
sends a thin prolongation forwards over the insertion of the abductor and
the short flexor of the little toe. The central portion, like the corre-
sponding part of the palmar fascia, is narrow behind, and becomes wider
and thinner towards the toes. At the back, where it is thickest, the fascia
is attached to the inner tubercle on the under surface of the calcaneum
immediately behind the origin of the flexor brevis digitorum, with which
muscle it is closely connected. Nearly opposite the middle of the meta-
tarsal bones, this fascia, becoming broader and thinner as it advances,
begins to divide into five processes, one for each of the toes ; and from this
point forwards to the base of the toes, numerous strong transverse fibres
are superadded, which bind the processes together, and connect them
closely with the skin. Near the articulation of the toes with the metatarsal
bones, each of the five processes divides, to permit the passage of the flexor
tendons ; and the two bundles of fibres resulting from the division of each
process, after strengthening the sheath of the tendons over which they pass,
are attached to the sides of the metatarsal bone, and are blended with the
transverse ligament uniting those bones. From the point of splitting of
each process, as in the hand, fibrous bands are continued forwards to the
skin in the division between the toe?.
The two intermuscular septa which lie between the middle and lateral
portions of the plantar fascia are prolonged deeply upwards into the sole
of the foot ; they separate the flexor brevis digitorum from the abductor
pollicis on the inner side, and from the abductor minimi digiti on the outer
side, and give partial origin to each of these muscles.
In both the foot and the hand there is a band of transverse fibres across
the roots of the digits, placed immediately beneath the skin, and connected
with the subjacent sheaths of the tendons. The digital nerves and vessels
are covered by this structure, which receives the name of transverse liga-
ment of the toes or fingers. In the foot a somewhat similar baud, but con-
sisting merely of a stronger part of the dorsal aponeurosis, crosses the place
of the metatarso-phalangeal articulations.
ANGEIOLOGY. THE HEART. 297
SECTION IV. ANGEIOLOGY.
UNDER the name of Angeiology is included the descriptive anatomy of the
vascular system, consisting of the heart, blood-vessels, and absorbents. The
Jteart is the central organ of the circulation, and, although presenting a com-
plex structure and mechanism, may be regarded, when viewed with reference
to its development, as a curved and greatly altered blood-vessel. The
blood-vessels are of three kinds viz., the arteries, or ramifying vessels which
distribute the blood from the heart ; the capillaries, or network of simple
walled microscopic vessels, in which the blood is diffused through the
tissues ; and the veins, or vessels by which the blood is returned to the
heart. The absorbents are the small and delicate vessels which convey into
the circulation fluid material capable of being converted into blood, whether
derived directly from the food digested in the alimentary canal, or returned
from the tissues in which it has already played some part in the nutritive
processes.
The double circulation. In the systemic circulation the blood is conveyed
from the left ventricle of the heart by the arteries to every part of the body,
and, having parted in the capillaries with a portion of its ingredients, and
undergone changes which render its purification necessary, it is returned by
the veins to the right side of the heart, which is distinct from that from
which it set out. The dark-coloured blood thus brought back to the right
side of the heart is conducted through the pulmonary circulation, being
propelled through the pulmonary artery by the right ventricle, undergoing
in the lungs a process of purification, in which it receives oxygen from the
air and parts with carbonic acid, and returning thence to the heart by the
pulmonary veins, again to enter the systemic circulation.
THE HEART.
RELATION TO SURROUNDING PARTS.
The heart is situated in the thorax, between the two lungs, and, together
with the adjacent parts of the great vessels which convey blood to and from
it, is enclosed by a membranous covering, the pericardium. It is placed
behind the sternum and the costal cartilages, occupying a region of about
four inches in width, extending from the second intercostal space on the
right side to the fifth space on the left, and reaching considerably farther on
the left than on the right of the middle line.
THE MEDIASTINUM.
The greater part of the thorax is occupied by the lungs, each of which is
invested with a serous membrane, the pleura, which presents a parietal and
a visceral portion, and is continued "from the one portion to the other by
passing on the surface of the pericardium from the anterior and posterior
parts of the walls of the chest to the root of the lung. Thus the heart,
enclosed in the pericardium, is situated between the right and left pleural
sacs, and between the layers of an antero-posterior septum formed by the
united portions of the right and left pleurse, and known as the mediastinum.
208
THE HEART.
Fig. 224.
THE MEDIASTINUM.
290
FROM THE EIGHT llDE IN A MALE ADULT.
A, Right auricle ; B, left auricular appendix ; C, right ventricle ; D, small part of the
left ventricle ; I, placed on the first part of the aortic arch ; and on the descending aorta ;
II, trunk of the pulmonary artery dividing into its right and left branches, and connected
to the aorta by the cord of the ductus arteriosus ; III, vena cava superior ; IV, vena cava
inferior.
1, innominate artery and right carotid ; 1', left carotid ; 2, right and left subclavian
arteries ; 3, intercostal vessels marked only in three spaces ; 4, above this figure the
inferior diaphragmatic arteries ; below it the creliac axis and superior mesenteric artery ;
5, renal arteries ; 6, above this figure the spermatic arteries, and below it the inferior
meseuteric ; 6', the farther course of the spermatic vessels, on the right side they are
seen to pass through the outer abdominal ring before descending to the testis ; 7, 7', right
and left common iliac arteries ; 8, 8', external iliac arteries ; 9, epigastric and circumflex
iliac arteries of the left side ; 10, 10', internal iliac arteries ; and between these two
figures the middle sacral artery ; 11, femoral arteries ; 12, some branches of the profunda
femoris artery of the left side.
a, right innominate or brachio-cephalic vein ; a', the left ; 6, b', right and left sub-
clavian veins ; V, the cephalic vein of the right arm ; c, d , internal jugular veins ; c",
right facial vein joining the internal jugular; d, external jugular veins formed by the
posterior auricular and temporal veins ; df, anterior jugular veins with the transverse
joining the external jugular; e, azygos vein passing over the root of the right lung ; /,
one of the hepatic veins ; g, placed on the vena cava inferior at the origin of the renal
veins ; to the sides are seen the kidneys and the suprarenal bodies ; g', right, g' 1 , left
ureter ; A, right spermatic vein ; h', the left, joining the left renal vein ; i, i, common
iliac veins ; i', i', external iliac veins ; k, femoral veins ; I, saphenous vein of the right
side.
The part of this septum behind the pericardium is distinguished as the
posterior mediastinum ; it is in front of the bodies of the vertebrae, and
within its cavity are the trachea, the oesophagus, the thoracic duct, the
descending aorta, the vena azygos, and the pneumogastric nerves, with lym-
phatic vessels and areolar tissue. The middle, mediastinum is the name
given to the larger space, which is occupied by the pericardium and its
contents. The anterior mediastinum, in front of the pericardium, is narrow
and of little depth ; but a knowledge of its situation is important to the phy-
Fig. 225. A DIAGRAMMATIC
REPRESENTATION OF THE
HEART AND GREAT VES-
SELS IN CONNECTION WITH
Fig. 225.
The pericardium has been
removed, and the lungs are
turned aside. 1, right au-
ricle ; 2, vena cava superior ;
3, vena cava inferior ; 4, right
ventricle; 5, stem of the pul-
monary artery ; a, a, its right
and left branches; 6, left
auricular appendage ; 7, left
ventricle ; 8, aorta ; 9, 10,
two lobes of the left lung ;
11, 12, 13, three lobes of the
right lung ; b, b, right and
left bronchi ; v, v, right and
left upper pulmonary veins.
sician, as it is connected
with the position of the
anterior margins of the
luns relatively to the heart : at its superior part a small interval is left
x 2
300 THE HEAET.
between the two layers of pleura which .bound it, and in this are contained
the vestiges of the thyinus gland ; behind the second piece of the sternum
the pleurae of opposite sides come into contact, and the anterior mediastinum
is reduced to a thin septum ; while lower down it is inclined to the left, and
widened out into an angular space of some breadth, by the margin of the
left pleura receding from the sternum : opposite the lower part of this space
the apex of the heart is situated, and in front of it is placed the triangularis
sterni muscle.
THE PERICARDIUM.
This membranous bag, in which the heart is contained, is of a somewhat
conical shape, its base being attached below to the upper surface of the
diaphragm, whilst the apex, or narrower part, surrounds the great vessels
which spring from the cavities of the heart, as far as their first subdivisions.
It consists of two layers, one external and fibrous, the other internal and
serous.
The fibrous layer is a dense, thick and unyielding membrane, consisting
of fibres which interlace in every direction. At the base of the pericardium
these fibres are firmly attached to those of the central aponeurosis of the
diaphragm ; and above, where the pericardium embraces the large blood-
vessels, the fibrous layer is continued on their surface in the form of tubular
prolongations, which become gradually lost upon their external coats. The
superior vena cava, the four pulmonary veins, the aorta, and the right and
left divisions of the pulmonary artery, in all eight vessels, receive pro-
longations of this kind.
The serous layer not only lines the fibrous layer of the pericardium and
the part of the diaphragm to which that layer is attached, but, like other
serous membranes, is reflected on the surface of the viscus which it invests.
It has, therefore, a visceral and a parietal portion. The parietal portion
adheres firmly by its outer surface to the fibrous membrane, and becomes
continuous with the visceral portion upon the arch of the aorta and other
great vessels, about two or two and a half inches from the base of the heart.
In passing round the aorta and pulmonary artery, it encloses both those
vessels in a single short tubular sheath. It is reflected also upon the
superior vena cava and on the four pulmonary veins, and forms a deep
recess or prolonged cavity between the entrance of the right and left veins
into the left auricle. The inferior vena cava receives only a very scanty
covering of this membrane, inasmuch as that vessel enters the right auricle
almost immediately after passing through the diaphragm, and is only
partially surrounded by a reflection of the pericardium in the narrow
interval between these parts. None of the vessels, indeed, joining the
heart, with the exception of the aorta and pulmonary artery where they are
united together, receive a complete covering from the pericardium, or can
be said to pass entirely through the sac : portions only of the membrane are
inflected round them more or less fully.
On separating- the left pulmonary artery and subjacent pulmonary vein, a fold of
the pericardium will be seen between them, which has been termed by Marshall the
"vestigial fold of the pericardium." It is formed by a duplicature of the serous
membrane, including areolar and fatty tissue, together with some fibrous bands,
blood-vessels, and nerves. It is from half to three-quarters of an inch in length, and
from a half to one inch deep. Above the pulmonary artery it blends with the peri-
cardium, and passes onwards to the left superior intercostal vein. Below, it is lost,
on the side of the left auricle, in a narrow streak which crosses round the lower left
THE PERICARDIUM.
Fig. 226.
301
Fig. 226. SEMI-DIAGRAHMAIIO VIEW OP THE PERICARDIUM FROM BEHIND, DESIGNED
TO SHOW THE PRINCIPAL INFLECTIONS OF THE SEROUS SAC ROUND THE GREAT
VESSELS, f
The drawing is taken from preparations in which the heart and vessels had been
partially filled by injection, the pericardium inflated and dried in the distended state, and
the fibrous continuation on the vessels removed. By the removal of a portion of the
pericardium from behind the right and left cavities of the heart, the position of that
organ is made apparent. A bent probe is passed within the pericardium from behind
the right auricle in front of the vena cava inferior to the back of the left ventricle, which
may indicate the place where the large undivided sac of the pericardium is folded round
that vein. A, posterior surface of the right auricle ; A', the same of the left ; V, right
ventricle ; V, left ventricle ; Ao, the upper and back part of the aortic arch ; b, innomi-
nate artery ; C, vena cava superior ; az, azygos vein ; C', vena cava inferior between the
diaphragm and its union with the right auricle ; c" , great coronary vein ; +, cord of the
ductus arteriosus ; P, the right, P', the left pulmonary artery ; p, the right, p', the left
pulmonary veins ; D, the back of the central tendon of the diaphragm ; 1, the great
undivided sac of the pericardium proceeding from before backwards towards its inflections
round the vessels; 2, portion of this on the right side which partially surrounds the vena
cava superior, the upper and lower right pulmonary veins, and the vena cava inferior ; 3,
the portion of the left side which partially surrounds the vena cava inferior ; 4, the
portion which is extended upwards behind the left auricle, and partially folds over the
pulmonary arteries and veins, and which meets between these different vessels the
extensions of the main sac from the right and left ; 5, tubular portion of the pericardium
which completely surrounds the aortic and pulmonary arterial trunks.
pulmonary vein. This is shown, by Marshall, to be a vestige of the cardiac termi-
nation of the great left anterior vein existing in early embryonic life. (Marshall,
" On the development of the great anterior Veins in Man and Mammalia," PMlosoph
Trans. 1850. Parti. See hereafter the figures of the coronary vein.)
302
THE HEART.
EXTERNAL FORM OF THE HEART.
The heart is a hollow muscular organ, divided by a longitudinal septum
into a right and a left half, each of which is again subdivided by a transverse
constriction into two compartments, communicating with, each other, and
named auricle and ventricle. Its general form is that of a blunt cone, flattened
on its under surface. The broader end, or base, by which it is attached, is
directed upwards, backwards, and to the right, and extends from the level
of the fourth to that of the eighth dorsal vertebra. The apex is turned
downwards, forwards, and to the left, and corresponds in the dead body with
the cartilage of the sixth rib. In the living subject its stroke against the
walls of the chest is felt in the space between the cartilages of the fifth and
sixth ribs, a little below and within the left mammilla. The heart, there-
fore, has an oblique position in the chest, and besides this is n on symmetrically
placed, as it projects farther into the left than into the right half of the
thoracic cavity, passing on an average about an inch or an inch and a half
beyond the middle line in the one direction, and upwards of three inches
in the other. Its position is affected more or less by that of the body ;
thus it comes more extensively into contact with the anterior walls of the
Fig. 227.
Fig. 227. VIEW OP THE HEART AND
GREAT VESSELS FROM BEFORE (from R.
Quain).
The pulmonary artery has been cut short
close to its origin in order to show the first
part of the aorta. 1, anterior part of the
right ventricle ; 2, left ventricle ; 3, root of
the pulmonary artery ; 4, ascending part of
the arch of the aorta ; 4', the posterior or
descending part of the arch ; between these
is seen the transverse or middle part from
which the brachio-cephalic arteries take their
origin ; 4", the descending thoracic aorta ;
5, the appendix and anterior part of the
right auricle ; 6, those of the left auricle ;
7, the right, and 7', left innominate or
bracbio-cephalic veins joining to form the
vena cava superior ; 8, the inferior vena
cava below the diaphragm ; 9 one of the
large hepatic veins ; +, placed in the right
auriculo-ventricular groove, points to the
right or posterior coronary artery ; + + ,
placed in the anterior interventricular
groove, points to the left or anterior coronary
artery.
chest when the body is in the prone
posture or lying on the left side.
In inspiration, on the other hand,
when the diaphragm sinks and the
lungs expand, its apex is withdrawn
from the thoracic parietes.
At its base the heart is directly attached to the great blood-vessels, and
it is also connected with them by the serous layer of the pericardium,
which passes from tho one to the other. In the remainder of its extent the
heart is entirely free, and movable within the sac of the pericardium. The
EXTERNAL FORM OF THE HEART.
303
anterior surface is convex in its general form ; it is turned upwards as well
as forwards, and is directed towards the sternum and costal cartilages :
from these, however, it is partly separated by the lungs, the forepart of
these organs advancing over it to some extent, and encroaching still farther
during inspiration, so as in that condition to leave usually not more than
two inches square uncovered. The posterior, which is also the under surface,
is flattened, and rests on the diaphragm. Of the two borders or margins
formed by the meeting of the anterior and posterior surfaces, the right or
lower border, called maryo acutus, is comparatively thin, and is longer than
the upper or left border, which is more rounded and is named margo
obtusus.
A deep transverse groove, the auriculo-ventricular furrow, interrupted in
front by the root of the pulmonary artery, divides the heart into the
auricular and the ventricular portions ; and on the ventricular portion two
longitudinal furrows indicate the position of the anterior and posterior
borders of the septum which divides one chamber from the other.
Fig. 228. VIEW OF THE HEART
AND GREAT VESSELS FROM
BEHIND (fromR.Quain). ^
1, posterior surface of the
right ventricle ; 2, the same of
the left ; 3, placed on the back
of the right pulmonary artery
near the division of the primary
trunk ; 3', branches of the
right pulmonary artery passing
into the root of the right lung ;
3", the same of the left; 4',
back part of the arch of the
aorta ; 4", descending thoracic
aorta ; 5, part of the right
auricle ; 6, is placed on the
division between the right and
left auricles ; 7, superior vena
cava ; 7', left vena inuominata ;
8, trunk of the inferior vena
cava ; 9, right large hepatic
vein; 10, 11, 12, right pul-
monary veins ; 13, 14, lef c
pulmonary veins; +, +, pos-
terior branches of the right and
left coronary arteries.
The auricular portion, situated above and behind the transverse furrow, is
thin and flaccid, and is immediately connected with the great veins ; it is
divided by an internal septum into two distinct cavities, which have received
the names of the right and left auricles, from the circumstance that each is
provided with an appendage somewhat resembling the ear of a dog. The
ventricular portion, placed below and in front of the transverse groove, is
somewhat conical, flattened on its posterior or under surface, has very thick
walls, and is connected with the great arterial trunks. The two longitudinal
furrows, which mark its division into a right and left chamber, situated one
on the anterior, the other on the posterior surface, extend from the base of
the ventricular portion, in a direct course, and are continuous one with the
other a little to the right of the apex, which is thus formed entirely by the
wall of the left ventricle. The anterior longitudinal furrow is nearer to
304 THE HEART.
the left border, whilst the posterior furrow approaches nearer to the right
border of the heart, the right ventricle forming more of the anterior, and
the left more of the posterior surface of the organ. Within the transverse
and longitudinal furrows are placed the proper nutrient vessels of the heart,
the coronary or cardiac arteries and veins, with the lymphatic vessels and
nerves imbedded in fatty and connective tissue.
INTERIOR OF THE HEART.
GENERAL DESCRIPTION. Considered in respect of function, the heart is a
double organ, composed of a right and a left part, each consisting of an
auricle and a ventricle. The right portion receives into its auricle from
the two vense cavse and coronary veins the dark venous blood returning
from the various parts of the body and from the heart itself, and, by means
of its ventricle, propels that blood through the pulmonary artery into the
lungs. The red blood returning from the lungs by the pulmonary veins,
reaches the left auricle of the heart, and is forced onwards by the left
ventricle, through the aorta and its branches, into every part of the body.
The right and left divisions of the heart present in various respects a
similar anatomical structure, and the features which are common to both
may here be shortly referred to before passing to those which are peculiar to
one auricle or ventricle.
Endocardium. The interior of the whole heart is invested with a lining
membrane, similar in general appearance to the visceral layer of peri-
cardium which covers the exterior, but belonging to the class of vascular
lining membranes, and continuous with that of the blood-vessels. This
internal lining, or endocardium, is a thin transparent membrane, differ-
ing slightly on the two sides of the heart. On the left side of the heart
it is continuous with the lining membrane of the pulmonary veins and
aorta, and is usually found more opaque than on the right side, whence
it is prolonged into the veins of the body and into the pulmonary
artery.
According to Theile, the endocardium is very thin on the musculi pectinati of the
auricles and on the columnse carneae of the ventricles. It is thicker, however, on the
smooth walls of the auricular and ventricular cavities, and on the musculi papillares,
especially near their tips. It is, on the whole, thicker in the auricles than in the
ventricles, and attains its greatest strength in the left auricle. In both auricles the
endocardium consists of three layers. On the free surface is an epithelial stratum of
polygonal cells. Beneath the epithelium is a network of elastic fibres, often con-
taining portions of fenestrated membrane ; and connecting the latter to the muscular
substance of the heart, is a layer of areolar tissue.; Purkinje and Eaeuschel (De
Arteriarum et Venarum Structure. Breslau, 1836.) found elastic fibres beneath
the endocardium in both auricles, and in the corpora Arantii, but not in the
ventricles. (
The auricles are each of them divisible into a large cavity, called the
atrium, or sinus venosus, and a much smaller part in front, the auricular
appendage, auricula, or auricle propei. The anterior of the atrium pre-
sents smooth walls in the greater part of its extent, but the walls of the
auricular appendages are thrown into closely set reticulated bands, which
in the right extend also into the sinus, and are named musculi pectinati.
The auricle, both on the right and the left side, receives the blood from
the veins, and transmits it into the corresponding ventricle by the auriculo-
ventricular opening.
INTERNAL STRUCTURE OF THE HEART.
305
The ventricles, on a great part of their inner surfaces, are covered with a
number of irregular rounded muscular bands, named columns carnece, which
form quite a net-work in some parts of the ventricle, and may be classified
into three kinds. The first kind form merely slightly prominent ridges on
the walls of the ventricle, being attached by one of their sides as well as by
the two extremities ; the second are adherent by their two ends only, and
are free in the rest of their extent ; whilst the third kind form a few
bundles, named musculi papillares, which are directed in general from the
apex towards the base of the ventricle, in which they are attached to the
muscular wall by their broader basis, and tapering more or less at their
free extremities give rise to small tendinous cords, chordce tendinece, through
which they are connected with the segments of the auriculo-ventricular
valve. Each ventricle has two orifices, an auriculo-ventricular and an
arterial opening.
Fig. 22
Fig. 229. VIEW OP THE BASE
OF THE VENTRICULAR PART
OP THE HEART, SHOWING
THE RELATIVE POSITION OP
THE ARTERIAL AND AU-
RICULO-VENTRICULAR ORIFI-
CES. |
The muscular fibres of the
ventricles are exposed by the
removal of the pericardium,
fat, bloodvessels, &c. ; the pul-
monary artery and aorta have
been removed by a section
made immediately beyond the
attachment of the semilunar
valves, and the auricles have
been removed immediately
above the auriculo-ventricular
orifices. The semilunar and
auriculo-ventricular valves are
in the closed condition. 1, 1,
the w base of the right ventricle ; 1', the conus arteriosus ; 2, 2, the base of the left
ventricle ; 3, 3, the divided wall of the right auricle ; 4, that of the left ; 5, the anterior,
5', the posterior, and 5", the left or septal segment of the tricuspid valve ; 6, the anterior
or aortic, and 6", the left and posterior segment of the mitral valve. In the angles
between these segments are seen the smaller fringes frequently observed ; 7, the anterior
part of the pulmonary artery ; 8, placed upon the posterior part of the root of the aorta ;
9, the right, 9', the left coronary artery.
Valves. In order to give to the blood propelled by the contraction of
the ventricles its due direction through the arteries, two sets of valves are
provided, one of which prevents the regurgitation of blood through the
auriculo-ventricular openings into the auricles during the contraction of the
ventricles, while the other prevents regurgitation from the arteries back into
the ventricles when the contraction has ceased. These valves are mainly
formed of folds of the endocardium with some fibrous tissue contained
within them.
The auriculo-ventricular valves are composed of membranous flaps or
segments, which are three in number in the valve of the right side, and
two in that of the left. At their bases, the several segments are con-
tinuous with one another, so as to form an annular membrane attached
round the margin of the auricular opening : they are directed downwards,
306
THE HEART.
and are retained in position within the ventricle by the chordae tendinese,
which are attached to their ventricular aui faces and free margins.
Fig. 230. VIEWS OP PARTS OP
THE SEMILUNAR AND MITRAL
VALVES, AS SEEN FROM WITHIN
THE VENTRICLE.
A, portion of the pulmonary
artery and wall of the right ven-
tricle with one entire segment and
two half segments of the semi-
lunar valves ; a, half the sinus of
Valsalva of the anterior segment ;
6, the same of the left posterior seg-
ment ; c, the entire right posterior
segment (See Fig. 231, A, in which
the lettering is the same as in the
present figure); d, d', inner sur-
face of the ventricle ; 1, the
attachment of the extremities of
the segments to the inner wall of
the artery ; 2, the middle of the
attached border of the segments ;
3, the middle of the free border
marked in two of the segments ;
upon the middle segment especially
the direction of the bands of fibres
strengthening the valve, as repre-
sented by Pettigrew, is shown.
B, portion of the aorta and wall
of the left ventricle with one entire
segment and two half segments of
the semiluuar valve, and the right
or anterior segment of the mitral
valve ; a, half the right anterior
sinus of Valsalva and segment
(marked b in B, fig. 231); b,
the same of the left side ; c, the
posterior sinus of Valsalva and
segment entire ; in a, and b, the
apertures of the coronary arteries
are seen ; d, d', the inner surface
of the wall of the ventricle to the
right of the auriculo-ventricular
orifice ; 1, 1, the attachments of
the extremities of the segments ; 2,
the middle of the attached borders ;
3, the middle of the free border
with the corpus Arantii shown in
the middle segment ; e, e', the
base of the right or anterior seg-
ment of the mitral valve ; /, its
apex ; between e, and e', and /,
the attachment of the branched chordae tendineas to the margin and outer surface of the
valve segment ; g, the posterior principal musculus papillaris ; h t the anterior principal
musculus papillaris : the cut chorJae tendinese are those which belong to the left or pos-
terior segment and the small or intermediate segments.
During the contraction of the ventricles, the segments of the valves are
applied to the openings leading from the auricles, and prevent the blood from
rushing back into those cavities. Being retained by the chordae tendinese,
the expanded flaps of the valve resist the pressure of the blood, which
THE VALVES.
307
would otherwise force them back through the auricular orifice ; the papillary
muscles, shortening as the cavity of the ventricle itself is contracted during
its systole, are supposed thus to prevent the valves from yielding too much
towards the auricle, which might have been the case had the chordae ten-
dineee been longer, or fixed directly into the wall of the ventricle. The
middle part of each segment is thicker than the rest, whilst the marginal
part is thinner, more transparent, and jagged at the edges. In the angles
between each pair of the principal segments of the atiriculo- ventricular valves
there may be found, but not constantly, as many small intermediate lobes.
The musculi papillares are arranged in groups as many as there are seg-
ments of the valve, and the chordae tendineae from each are distributed
to the adjacent sides of two different valves, so as to draw their margins
together,
According to Kurschner (Wagner's Handwb'rterbuch, art. " Herzthatigkeit "\ three
kinds of cords belong to each segment : a, the first set, generally two to four in number
and proceeding from two different sets of papillae, or from one of these and the
wall of the ventricle, run to the base or attached margin of the segment, and are
there connected also with the tendinous ring round the auriculo-ventricular opening ;
b, the second set, more numerous, and smaller than the first, proceed also from two
adjacent papillary muscular groups, and are attached to the back or ventricular surface
of each segment at intervals along two or more lines extending from the points of
attachment of the tendons of the first order at the base of the valve to near its free
extremity ; c, the third set, which are still more numerous and much finer, branch
off from the preceding ones, and are attached to the back and edges of the thinner
marginal portions of the valves. A few muscular fibres prolonged from the
neighbouring walls penetrate into the segments of the auriculo-ventricular
valves.
Fig. 231.
Fig. 231. THE SEMILUNAR VALVES OF
THE AORTA. AND PULMONARY ARTERY,
SEEN FROM THEIR DlSTAL SlDE.
A, transverse section of the pulmonary
artery immediately above the attach-
ment of the semilunar valves : a, the
anterior segment ; &, the left, and c, the
right posterior segments : in each the
sinus of Valsalva is seen, and between
them the attachment of the ends of the
valve- segments to the inner wall of the
artery.
B, a similar section of the aorta,
showing the semilunar valves from their
distal side : a, the left, &, the right
anterior segments, with the sinuses of
Valsalva, from which the corresponding
coronary arteries are seen to take their
origin ; c, the posterior segment ; d,
the right, or posterior ; 0, the left, or
anterior coronary arteries.
The semilunar or sigmoid valves,
placed at the mouths of the aorta
and pulmonary artery, consist of three semicircular folds, each of which is
attached by its convex border to the side of the artery at the place where
it joins with the ventricle, whilst its other border, nearly straight, is free,
and projects into the interior of the vessel. They are composed of dupli-
308 THE HEART.
catures of the endocardium, and of enclosed fibrous structure, which varies
in thickness at different parts. A tendinous band strengthens the free
margin of the valve, and is attached at the middle of that margin to a slight
fibro-cartilaginous thickening, the nodulus or corpus Arantii. Other ten-
dinous fibres, spreading out from the attached border of the valve, run
into the valve and towards the nodule, occupying its whole extent, except
two narrow lunated portions, one on each side, adjoining the free margin of
the valve. These parts, which are named lunulce, are therefore thinner than
the rest. There is also a strengthening fibrous cord surrounding the
attached border of each valve. (For further information regarding the
structure of the valves, consult Pettigrew, in Trans. Roy. Soc. Edin.
1864.)
During the contraction of the ventricle the valves lie against the sides of
the artery, and allow the blood to flow freely past them ; but during the
ventricular diastole, when the column of fluid in the artery is partially
thrown back by the elasticity of the coats of that vessel, the sigmoid valves
are distended by the regurgitating blood, and completely close the arterial
orifice. When the valves are thus closed, the whole free border and the
thin lunated parts are closely applied to each other, and are held together
as well as exempted from strain by the opposite and equal pressure of the
blood on either side, so that the greater the pressure the more accurate
must be the closure. The force of the reflux is sustained by the stouter
and more tendinous part of the valve. (Retzius, in Miiller's Archiv., 1843,
p. 14.)
Opposite the pouches formed by the sigmoid valves, the commencing
aorta and pulmonary artery present dilatations or recesses in their walls,
called sinuses of Valsalva, which give to the transverse section of the vessel
a trilobate form ; and, as one of these is placed behind each segment of the
valve, it thus forms along with it a cup-shaped cavity.
SPECIAL DESCRIPTION. The detailed anatomy of the four cavities of the
heart may be conveniently considered in the order of the course of the
blood in its double circulation through them from the vense cavse to the
aorta.
1. The RIGHT AURICLE forms the right anterior and lower part of the
base of the heart, and is in contact below with the pericardium where it
lies upon the diaphragm : it receives blood in two large streams, from
the superior and the inferior vense cavse, besides the smaller quantity from
the coronary vein. At its fore part its auricular appendage projects for-
wards and to the left, in front of the aorta, as far as the pulmonary artery.
This part is triangular in form, compressed and slightly dentated at its
border, and has more strongly muscular walls than the sinus venosus.
The auricular appendage and anterior wall of the sinus venosus are
closely ridged in a vertical direction with musculi pectinati ; the remaining
parts of the walls are comparatively smooth. The superior vena cava is
directed downwards and forwards into the upper part of the auricle, while
the inferior vena cava terminates in the lower and back part by a consider-
ably larger opening, which is directed upwards and inwards. In the floor
of the auricle, in front of the inferior vena cava, is the auriculo-ven-
tricular opening, leading into the right ventricle ; it is oval in form, and
about an inch and a quarter in diameter, admitting three fingers easily.
The other foramina opening into the right auricle are, the orifice of the large
coronary vein of the heart, situated between the opening of the inferior
vena cava and the auriculo- ventricular opening, and a number of small pits,
THE RIGHT AURICLE.
309
foramina Thebesii, some of which are recesses closed at the bottom, whilst
others are the mouths of minute veins (vence minimse cordis).
The left and posterior side of the auricle is formed by the septum auricu-
Fig. 232. THE RIGHT Fig. 232.
AURICLE AND VEN-
TRICLE OPENED AND A
PART OF THEIR RlGHT
AND ANTERIOR WALLS
REMOVED SO AS TO SHOW
THEIR INTERIOR. |
1, the superior vena
cava ; 2, the inferior vena
cava at the place where it
passes through the dia-
phragm, and below the
hepatic veins ; 2', the
hepatic veins cut short ; 3,
placed upon the tubercle
of Lower within the cavity
of the right auricle ; 3',
placed in the fossa oval is,
below which is the Eusta-
chian valve ; 3", is placed
close to the aperture of
the great coronary vein
and the valve of Thebe-
sius ; +, +, placed in
the auriculo - ventricular
groove, where a narrow
portion of the adjacent
walls of the auricle and
ventricle has been pre-
served ; 4, 4, the cavity
of the right ventricle on
the right side of the sep-
tum, the upper figure is
immediately below the
semilunar valves ; 4',
large right columna car-
nea ; 5, the anterior ; 5',
the posterior, and 5", the left or septal segment of the tricuspid valve ; 6, placed in the
interior of the pulmonary artery, a part of the interior wall of that vessel having been
removed, and a narrow portion of it preserved at its commencement where the semilunar
valves are attached. The valves are represented as in a half-closed position ; two of the
segments are seen foreshortened, the third sideways ; 7, concavity of the aortic arch close
to the cord of the ductus arteriosus ; 8, ascending part or sinus of the arch covered at
its commencement by the auricular appendix and pulmonary artery ; 9, placed between
the innominate and left common carotid arteries; 10, appendix of the left auricle;
11, 11, the outside of the left ventricle, the lower figure near the apex.
laruvi, a partition which separates it from the left auricle, At the lower
part of this septum, and just above the orifice of the inferior vena cava,
is situated an oval depression named fossa or fovea ovalis, which is the
vestige of the foramen ovale of the foetal heart (vestigium for aminis ovalis),
and indicates the original place of communication between the two auricles.
It is bounded above and at the sides by a prominent border, which is
deficient below, the annulus ovalis or isthmus Vieussenii. Continuous
with the anterior inferior extremity of the annulus ovalis is a crescentic
fold of endocardium, the Eustachian valve, springing from the anterior
310 THE HEAET.
margin of the inferior vena cava. This valve, which in the foetus is pro-
portionally large, and serves, in conjunction with the ammlus ovalis, to
direct the blood from the inferior vena cava through the foramen ovale, is in
the adult comparatively small, and very variably developed, being often cribri-
form or perforated by numerous foramina, and sometimes reduced to a few-
slender filaments, or even altogether wanting. The mouth of the coronary
vein is likewise protected by a semicircular valve, which is sometimes
double, and which, though previously figured by Eustachius, is often named
the valve of Thebesius. The coronary vein is considerably dilated before it
enters the auricle, and this dilated portion, which has muscular parietes,
is commonly termed the 4< coronary sinus." At the junction of the coronary
vein with this dilated portion, there is a valve consisting of one or two
segments. Other small veins likewise enter the coronary sinus, each of
them protected by a valve.
The superior and inferior venae cavse being both directed somewhat
towards the left side at their terminations, the wall of the auricle presents
internally a convexity between them, which has received the somewhat
misleading name of tubercle, of Lower. In the human subject this elevation
is slight, but in certain quadrupeds it is more strongly marked.
Kunning upwards from the fossa ovalis, under cover of the annulus, there some-
times exists a small slit, which leads beneath the annulus into the left auricle,
forming thus an oblique and valved aperture between the two cavities. More rarely
the foramen ovale of the foetus remains so patent after birth as to interfere with the
proper course of the circulation, and produce the pathological condition known as
cyanosis by the mixture of some dark or venous blood with the bright red or
arterial blood of the left auricle.
2. The RIGHT or ANTERIOR VENTRICLE extends from the right auricle
towards the apex, and from the upper and anterior part of its base sends
upwards, in front and to the left of the auriculo-ventricular opening, a
smooth conical prolongation, free from columiiae carnese, and named infundi-
bulum or conus arteriosus : from the extremity of this prolongation of the
ventricular cavity the pulmonary artery arises. The superficial wall of this
ventricle, which is much thicker than that of the auricle, but thinner than
that of the left ventricle, is formed by the part of the heart situated to
the right of the anterior longitudinal groove, viz., the right border, the
larger part of the anterior surface, and a part of the posterior. The internal
or left wall is formed by the septum ventriculorum, and is convex, bulging
to the right into the ventricle, so that a transverse section of the cavity
presents a crescentic figure.
The valve guarding the right auriculo-ventricular opening is named the
tricuspid valve, from the number of its segments. One of the segments,
the smallest, is placed towards the left and rests upon the septum of the
ventricles ; the other two are placed more to the right, one posteriorly
against the right wall of the cavity, while the other, the largest of all, lying
anteriorly, is interposed between the auricular and arterial openings, and
has its ventricular surface directed forwards and upwards. The chordae
teiidiiiese arise chiefly from the musculi papillares, but some also from the
walls of the ventricle and especially from the septum. Those arising from
one papillary muscle or group of muscles run up in the angular interval
between two adjacent segments of the valve, and, diverging from each other,
are attached to both segments.
The semilunar valves at the root of the pulmonary artery are more
THE LEFT AURICLE.
311
delicate than those which guard the aorta ; and the sinuses of Valsalva are
less strongly marked.
3. The LEFT AURICLE occupies the left and posterior part of the base of
the hearfc. When distended, the atrium presents from behind, where it is
best seen, a quadrilateral appearance. In front it rests against the aorta
and pulmonary artery ; behind, on each side, it receives two pulmonary
veins, those from the left lung entering very clo-e together ; and on the
right it is in contact with the other auricle. The auricular appendage is
Fig. 233. THE LEFT AURTCLE Fig. 233.
AND VENTRICLE OPENED AND
A PART OP THEIR ANTERIOR
AND LEFT WALLS RKMOVKD
SO AS TO SHOW THEIR IN-
TERIOR. |
The pulmonary artery Las
been divided at its commence-
ineut so as to show the aorta :
the opening into the left ven-
tricle has been carried a short
distance into the aorta between
two of the segments of the
semilunar valves ; the left
part of the auricle with its
appendix has been removed.
The right auricle lias been
thrown out of view. 1, the
two right pulmonary veins cut
short : their openings are seen
within the auricle; 1', placed
within the cavity of the auricle
on the left side of the septum
and on the part which forms
the remains of the valve of the
foramen ovale, of which the
crescentic fold is seen towards
the left hand of 1 ; 2', a narrow
portion of the wall of the auricle
and ventricle preserved round
the auriculo-ventricular orifice;
3, the left part, 3', the right
part towards the septum of the
cut surface of the wall of the
ventricle, seen to become very
much thinner towards 3", at
the apex ; 4, a small part of
the anterior wall of the left
ventricle which has beeu pre-
served with the principal an-
terior columna carnea attached to it ; 5, 5, the large posterior columnse Caracas ; 5', the
left side of the septum within the cavity of the left ventricle ; 6, the right or aortic seg-
ment, and 6', the left or parietal segment of the mitral valve; 7, placed in the interior of
the aorta near its commencement and above the three segments of its semilunar valve which
are hanging loosely together ; 7', the exterior of the great aortic sinus ; 8, the upper part
of the conus arteriosus with the root of the pulmonary artery and its semilunar valves ;
8', the separated portion of th e pulmonary artery remaining attached to the aorta by 9,
the cord of the ductus arteriosus ; 10, the arteries rising from the summit of the aortic
arch.
the only part of the left auricle seen from the front : it extends forwards
from the left side of the atrium, and curves towards the right side, resting
312
THE HEART.
on the pulmonary artery. It is more curved than that of the right auricle,
and its margins are more deeply indented,
The interior of the appendix presents musculi pectinati somewhat similar
to those in the right side of the heart, but the walls of the sinus venosus
are altogether smooth, and are also thicker than those of the right auricle.
Posteriorly are the openings of the pulmonary veins, usually two on each
side, and entirely without valves. The two veins of either or both sides
sometimes unite into one before entering the auricle, whilst in other cases
there is found an additional opening, most frequently on the right side. In
the lower and fore part of the auricle is situated the left auricula-ventricular
orifice. It is of an oval form, and is rather smaller than the corresponding
opening between the right auricle and ventricle. On the septum between
the auricles, a slight lunated mark or depression may be observed, which is
the vestige of the foramen ovale, as it appears on the left side. The
depression is limited by a slight crescentic ridge, the concavity of which is
turned upwards, and which is in fact the now adherent border of a mem-
branous valve, which during foetal life is applied to the left side of the then
open foramen ovale.
4. The LEFT or POSTERIOR VENTRICLE occupies the left border of the heart,
but only about a third of its extent appears on the anterior surface of the
organ, the rest being seen behind. It is longer and narrower than the right
ventricle, forming by itself the apex of the heart, as the right ventricle does
not reach into that part. The cross section of its cavity is oval, not crescentic,
the septum on this side being concave. Its walla, which, excepting near the
Fig. 23 i. Fig. 234. CKOSS SECTION OF
THE VENTRICULAR PAKT OF
THE HEART AT TWO-THIRDS
FROM THE APEX, LOOKING
INTO THE CAVITIES TOWARDS
THE APEX. I
1, 1', cut surface of the wall of
the right ventricle; 2, 2', the
same of the left ; 3, 3', the same
of the septum ; 4, the principal
columna carnea of the right ven-
tricle on its right border ; 4',
some of those on the septum near
the front ; 4", some of those on
the posterior wall near the sep-
tum ; 5, the principal anterior
columna carnea of the left ven-
tricle ; 5', the largest of those
situated posteriorly in the left
ventricle ; 6, the deepest part of the cavity of the right ventricle ; 7, that of the left
ventricle at the apex of the heart.
apex, are three times as thick as those of the right ventricle, are thickest at
the part where the ventricle is widest, about one fourth of its length from the
base ; from this point they become thinner towards the auricular opening,
but they are still thinner towards the apex which is the weakest part. The
lining membrane, which is continuous with that of the left auricle and the
aorta, is usually less transparent than that of the right ventricle, especially
in later life. In the interior of the cavity are noticed column se carneze,
musculi papillares with chordae tendineae, and two orifices guarded with
valves. The columnce carnece are, on the whole, smaller than those of the
right ventricle, but are more numerous and more densely reticulated.
THE LEFT VENTRICLE. 313
Their intersections are very numerous near the apex of the cavity, and also
along its posterior wall, but the upper part of the anterior wall and septum
is comparatively smooth. The musculi papillarcs are collected into two
bundles, which are larger than those of the right ventricle, and are formed
one from the anterior, the other from the posterior surface of the ventricle.
The two orifices of this ventricle are situated very close together, with one
of the segments of the auriculo-ventricular valve between ; the auriculo-
ventricular opening being placed at the left and posterior part of the base of
the ventricle, behind and to the left of that which leads into the aorta.
The bicuspid or mitral valve, which guards the auriculo-ventricular open-
ing, resembles in structure the tricuspid valve of the right ventricle, but it
is much thicker and stronger in all its parts, and consists of only two
pointed divisions or segments, continuous at their attached bases. The
larger of the two segments is suspended obliquely to the right and in front
of the other, between the auricular and the aortic orifices : the smaller is
situated to the left and posteriorly, and close to the wall of the ventricle.
There is usually a smaller lobe at each angle of junction of the two principal
segments, more apparent than those of the tricuspid valve.
One portion of the chordae tendinese from each musculus papillaris is
distributed to half of one segment, and the other portion to the neighbour-
ing side of the other segment, so that, when the musculi papillares contract,
and make the segments tense, they also cause their margins to approach each
other. The chordae tendineas are stronger and less numerous than in the
right ventricle.
The arterial or aortic orifice, circular in form, and smaller than the
auriculo-ventricular, is placed in front and to the right of that opening,
and very close to it, being separated from it only by the attachment of
the anterior segment of the mitral valve. The semilunar valves which
guard it are thicker and stronger than those of the right side of the heart,
the lunulse are more strongly marked off, and the central nodules, or corpora
Arantii, are larger. The sinuses of Valsalva are more strongly marked at
the mouth of the aorta than at the commencement of the pulmonary artery,
and from the two anterior of them arise the right and left coronary
arteries for the supply of blood to the substance of the heart.
POSITION OF THE PARTS OF THE HEART WITH RELATION TO THE WALL
OF THE THORAX.
The exact position of the various parts of the heart is important in
reference to auscultation. This subject has of late been carefully investigated
by several anatomists ; but there is still some discordance in their state-
ments on some points, caused probably by the difficulty of marking with
precision the situation of non-symmetrical viscera in artificially opened
bodies, and in part perhaps by differences naturally existing among indi-
viduals. The following statement derived from Luschka is in general accor-
dance with the results of others, with the exception, as remarked by Walshe,
that most of the positions are fixed a little too high. Nearly two-thirds of
the bulk of the heart lie to the left of the middle line. The upper edge
of the auricles corresponds with a line extending across the sternum from
the second right into the first left intercostal space. The auriculo-ventricular
sulcus corresponds with a line which unites the sternal end of the fifth right
costal cartilage with the second left intercostal space beneath the middle of
the second costal cartilage. The rounded margin formed by the wall of the
Y
314
THE HEART.
left ventricle extends from the second left intercostal space to a point in the
fifth space placed two inches vertically below the nipple. The sharp margin
formed by the right ventricle passes from the sternal end of the fifth right
costal cartilage, and crosses behind the end of the body of the sternum and
the sixth left costal cartilage, to meet the other margin at the apex.
Fig. 235.
Fig, 235. SEMI-DIAGRAMMATIC REPRESEKTATION OF THE CHEST, WITH THE INTERCOSTAL
SPACES DISSECTED IN FRONT TO SHOW THE POSITION OF THE HEART AND GREAT
VESSELS, AS SEEN BEHIND THE STERNUM AND COSTAL CARTILAGES (from Luschka and
A. Thomson).
a, right clavicle ; b, scalenus anticus muscle ; c, sterno-mastoid muscle divided ; c7, pec-
toral muscles divided ; + , axillary nerves above the subclavian artery ; e, trachea below the
isthmus of the thyroid body; /, /, upper surface of the diaphragm ; g, g, surface of the
lungs ; </, on the left side, apex of the lung or pleura appearing in the neck ; h, right, h' ',
left lobe of the liver ; i } stomach ; &, k, transverse colon ; I, to X, first to tenth ribs near
POSITION IX THE THORAX. 315
their cartilages ; 1, placed on the lower part of the manubrium of the sternum, and on the
place of the arch of the aorta indicated by dotted lines ; 2, placed in the second left in-
tercostal space, on the stem of the pulmonary artery ; 3, apex of the right auricle ; 3',
its most prominent part, behind the third space ; 3", its lower part at the junction of the
sixth and seventh right costal cartilages with the sternum ; 4, left auricular appendix ;
5, 5, right ventricle ; 6, left ventricle ; 6', apex of the heart : the white line outside the
heart is intended to indicate the external pericardium, as if the anterior half were re-
moved by a transverse incision; 7, 7, vena cava superior; 8, 8, internal jugular veins ;
9, 9, subclavian veins, joining the jugular ; 9, 7, 9, innominate veins ; the right rising
behind the sterno-clavicular articulation, the left crossing obliquely behind the upper
half of the manubrium. The position of the first parts of the innominate artery, left
carotid and left subclavian arteries, is indicated behind and below this vein ; 9', 9', outer
part of the subclavian arteries. It is to be observed that in this figure the attachment
of the sixth costal cartilage to the sternum is represented a little too high.
The auriculo-ventricular openings lie in the line of the auriculo-ventri-
cular sulcus. The middle of that of the right side lies behind the sternum,
between the fourth costal cartilages, and extends to the fifth left costal
cartilage. The middle of the left auriculo-ventricular opening is in the
second intercostal space, less than an inch to the left of the sternum ; but
as it is placed deeply, and overlaid by the arterial openings, the part imme-
diately over it is unfavourable for auscultation, which is therefore best
conducted at the point of impulse. The orifice of the pulmonary artery,
according to Luschka, is placed immediately to the left of the sternum,
opposite the second intercostal space, the free margin of the anterior valve
reaching up to the lower border of the second rib. The aortic orifice,
behind the insertion of the third left costal cartilage and the sternum, is on
a slightly lower level than the orifice of the pulmonary artery, and is
covered by it in two-thirds of its breadth. The aortic orifice being thus
concealed, the sounds produced within it are best heard at the spot where
the aorta approaches nearest to the surface, viz., opposite to the first and
second intercostal spaces at the right margin of the sternum. (Luschka,
Die Brustorgane, 1857 ; and Anatomie des Menschen, &c., 1863 ; Walshe,
Diseases of the Heart and Great Vessels ; Sibson, On the Normal and
Abnormal Situation and Structure of the Viscera of the Chest, in Trans, of
the Proviuc. Med. and Surg. Assoc. , vol. xii., year 1842, and in his Work
on Medical Anatomy ; Allen Thomson, Notice of the case of E. Groux, &c.,
with Observations on the Position and Actions of the Heart, in Glasgow
Med. Journ. April, 1858.)
The following additional particulars are taken from the observations of Allen
Thomson. The summit of the aortic arch is on a level with the middle of the
manubrium sterni ; and the left border of the innominate artery at its origin from the
arch is slightly to the left side of the middle line. The middle of the commencement
of the aorta, where it springs from the left ventricle, is behind the left border of the
sternum, on a level with the lower edge of the third costal cartilage. The ascending
part of the aorta bulges beyond the right border of the sternum to the extent of at
least a quarter of an inch ; and the vena cava superior extends about half an inch
farther in the same direction. The trunk of the pulmonary artery is wholly to the
left of the middle line, and its left border is about three-quarters of an inch beyond
the left border of the sternum. The concavity of the aortic arch is on a level with the
junction of the manubrium with the body of the sternum.
The right auricular appendage covers the lower part of the ascending aorta to the
right of the pulmonary semilunar valves, and its point is exactly behind the middle
line on a level with the upper border of the third costal cartilages.
The most projecting part of the right ventricle with the conus arteriosus lies
behind the sternum, between the lower end of the body and the inner part of the
left third intercostal space.
The right auricle extends to fully an inch beyond the right border of the sternum.
Y 2
316 THE HEAET.
The apex of the heart is situated about three and a-half inches to the left of the
middle line, and in the fifth intercostal space. The apex of the left auricular appen-
dage is in the lower part of the second intercostal space or behind the third costal
cartilage, about an inch and a quarter from the left of the sternum.
FIBROUS AND MUSCULAR, STRUCTURE OF THE HEART.
The heart consists chiefly of muscular tissue ; but besides this and the
thin membranes investing its surface and lining its cavities, there enter
into the formation of its wall, numerous blood-vessels, absorbents, and
nerves, together with more or less fat and some areolar tissue.
THE FIBROUS TISSUE belonging to the heart, besides what enters into the
structure of the different valves and the chordae tendinese, is found princi-
pally surrounding the auriculo- ventricular and great arterial orifices. When
we view the base of the heart so placed that the two auriculo-ventricular
orifices, which are separated only by the upper edge of the septum ventri-
culorum, are side by eide, instead of the right being somewhat in front of
the left, as is the case dm ing life, the aortic opening is seen to occupy a
position between and in front of them, and to have the opening of the
pulmonary artery immediately in front of it. The wall of the aortic opening
is firmly blended opposite one of the semilunar valves with the forepart of
the right margin of the left auriculo-ventricular opening ; and opposite the
angle between the other two valves it is in close contact with the margin of
the right auriculo-ventricular openings. In the angle between the aortic and
two auriculo-ventricular openings there is found a small fibro-cartilaginous
mass, which in some large animals, as the ox and elephant, is replaced by a
piece of bone. From this nodule a thick process extends backwards
between the two auriculo-ventricular orifices beneath the septum auricu-
larum, and others pass forwards forming bands, one on each side of the
aortic opening. These processes form the bases of what have been elabo-
rately described by authors as the fibrous or tendinous rings of the auriculo-
ventricular openings. These rings, and others which are described as
bounding the arterial orifices, have had a great importance imputed to them
as being the tendons of origin of the ventricular muscular fibres, a view
which, however, from recent investigations to be presently noticed, appears
to be incorrect. The rings around the auriculo- ventricular orifices consist of
only a small quantity of loose, white, fibrous tissue, continuous with that
which is found in the segments of the valves, strengthened on the sides
next the septum by the processes from the fibro-cartilaginous nodule. The
rings of the arterial orifices have been described by authors, and also in the
previous editions of this work, as each formed by a fibrous band or zone,
one edge of which is even, and gives attachment to the muscular fasciculi
of the ventricle, whilst the other is scalloped into three deep semilunar
notches, and is firmly fixed to the middle coat of the large artery. This
scalloped margin is simply the line of junction of the endocardium with the
festooned line of attachment of the semilunar valves and termination of the
artery, strengthened however by areolar tissue. The fibres of the middle
coat of the artery also, opposite the sinuses of Valsalva, are not arranged
annularly as in other parts of the vessel, but diverge from between the
sinuses, and spread upwards and laterally on the walls of the vessel ; and
the attachment of the artery to the ventricle is principally effected by
fibrous tissue continuous with the middle coat of the artery and with the
fibrous tissue in the valves, which spreads out between the small fasciculi of
the muscular substance, and is firmly connected with it.
MUSCULAR STRUCTURE AUEICLES.
317
THE MUSCULAR FIBRES of the heart in their mode of action belong to the
involuntary class, but are of a deep red colour, and possess the transversely
striated structure. They are smaller than the ordinary voluntary muscular
fibres : their striation is frequently as distinct in a longitudinal as in a
transverse direction : and not only is there an exceedingly intricate inter-
lacement of both fasciculi and fibres, but the latter appear to divide and
unite frequently with each other so as to produce a finely reticulated structure.
Fig. 236. HEART OP A YOUNQ Fig. 236.
SUBJECT DISSECTED AFTER
BOILING TO SHOW THE SUPER-
FICIAL MUSCULAR FIBRES,
SEEN ANTERIORLY.
This figure is planned after one
of Luschka's, but its details have
been hiefly taken from an original
preparation. The aorta and pul-
monary arteries have been cut
short close to the semilunar valves,
so as to show the anterior fibres
of the auricles. a, superficial
layer of the fibres of the right;
ventricle ; b, that of the left ;
c, c, anterior interrentricular
groove, from which the coronary
vessels have been removed, show-
ing at the upper and lower part
most of the fibres passing across
from the right to the left ven-
tricle, while in the middle part
some dip into the septum ; a',
pulmonary artery ; &', aorta ; d,
right auricle ; d', its appendix,
both showing chiefly perpen-
dicular fibres; e, upper part of
the left auricle ; between e, and 6',
the transverse fibres which behind
the aorta pass across both auricles ; g', appendix of the left auricle ; /, superior vena
cava, round which, near the auricle, circular fibres are seen ; g, </, right and left pul-
monary veins with circular bands of fibres surrounding them.
The fibres of the auricles are not continuous with those of the ventricles,
the two sets being connected together only by the intervention of the thin
fibrous rings round the auriculo- ventricular orifices ; so that when these
rings are destroyed by boiling a heart for some hours, the auricles may be
easily separated from the ventricles.
Fibres of the auricles. These consist of a superficial set, common to
both cavities, and of deeper fibres proper to each. 1. The superficial common
or transverse fibres run transversely over both sinuses, near the base, and
are most numerous on the anterior surface : some of them pass into the
interauricular septum. The deeper fibres, which are proper to each auricle,
consist of two sets, viz. the looped and the annular fibres. 2. The looped
fibres pass over the auricle, and seem to be attached by both extremities to
the corresponding auriculo- ventricular rings. 3. The annular fibres encircle
the auricular appendages from end to end, some longitudinal fibres running
within them. These annular fibres also surround the entrances of the venae
cavse on the right, and of the coronary vein and the pulmonary veins on the
left side of the heart, the muscular fibres extending for some distance
318
THE HEART.
from the auricle upon the veins, especially upon the superior vena cava and
the pulmonary veins.
Fibres of the ventricles. The muscular fibres of the ventricles have a
very intricate disposition, which has received great attention from various
anatomists, such as Wolff, Gerdy, Reid, Searle, and most recently Pettigrew,
the last of whom has done much to elucidate the nature of the arrangement
in animals, although perhaps the whole subject cannot yet be considered as
fully understood.
Fig. 237. Fig. 237. POSTERIOR VIEW OP
THE SAME PREPARATION AS
IS REPRESENTED IN THE PRE-
CEDING FIGURE. |
a, posterior surface of the
right ventricle with its super-
ficial muscular fibres dissected ;
b, the same of the left ventricle ;
c, posterior interventricular
groove, from which the coronary
vessels have been removed ; d,
right auricle ; e, the left,
showing some transverse fibres
common to both auricles, and
some belonging to each one ; /,
superior vena cava ; g, g f , pul-
monary veins cut short; h,
sinus of the great coronary
vein covered by muscular fibres ;
h', posterior coronary vein join-
ing the principal one ; i, inferior
vena cava ; i', Eustochian valve
as seen from behind.
It is chiefly the reticu-
lated structure or continual
union of the greater part
of the muscular fibres with
each other which renders
difficult the investigation
of the course and disposition of these fibres. In order to unravel them
with any degree of success, it is best to boil the slightly distended
heart for five or six hours, so as to destroy the connective tissue, and then
carefully to dissect the heart in part by cutting and in part by tearing
asunder the fibres with blunt instruments.
According to Pettigrew's observation?, made principally upon the hearts of rumi-
nating animals, as many as seven layers of fibres may be distinguished in the walls of
both ventricles ; * three of these being external, three internal, and one situated inter-
mediately between them : but it may be remarked that, although some of these
layers, such as the external, may be readily separated from the next, others of them
run so much into those with which they are in contact, that we must regard the dis-
tinction of layers as applying more strictly to the difference of the direction of the
majority of the fibres at different depths, than to a real and constant separation of
determinate layers, in each of which the fibres are alike in direction. At the same
time, for the convenience of description, it may be well to recognise provisionally the
seven layers of Pettigrew.
One of the most important facts which have been established by Pettigrew's
Wolff conceived that five or six layers might be made out.
MUSCULAR STRUCTURE VENTRICLES.
319
researches, is that of the continuity of the fibres of certain external layers with those
of corresponding internal layers. This continuity takes place at the base of the heart
round the auriculo-ventricular orifices and upon the septum, and at the apex of the
left ventricle in that peculiar spiral concentration of the fibres known to previous
observers as the vortex or whorl. Thus the fibres of the first or external layer are
continuous with those of the deepest or innermost, in part by folding over the margin
of the auriculo-ventricular orifice, and in part by penetration through the apex. In
the same manner the fibres of a second or deeper external layer are continuous with
those of a layer named the sixth by Pettigrew, and the fibres of the third external
layer with those of the fifth ; while the fibres of the middle or fourth layer of Petti-
grew may be considered to return upon those of the same set. In this manner the
first and seventh layers enclose all the others, the second and sixth enclose those
within them, and the third and fifth enclose the fourth.
The fibres of the ventricles, therefore, do not take their origin, as was in general
previously held, from the fibrous rings surrounding the auriculo-ventricular orifices
Fig. 238.
Fig. 238. VIE\V OP A PARTIAL DISSEC-
TION OP THE LAYERS OP FIBRES OP
THE VENTRICLES IN A SHEEP'S HEART
IN FRONT (after the manner of Pet-
tigrew). |
At the base and apex the pericardium
and connective tissue and fat alone have
been removed, and the superficial layer
of fibres is displayed on these parts of
both ventricles. In the intervening
space, layer after layer of the fibres has
been removed from above downwards,
reaching to a greater depth on the left
than on the right side, a 1 , a 1 , the
superficial layer of the right ven-
tricle ; b\ ft 1 , the same of the left
ventricle ; 2, the second layer of both
ventricles ; 3, the third ; 4, the fourth or
central, with fibres nearly transverse; 5
and 6, two of the deeper layers coming
next ; and 7, a small part of the fibres
of the deepest layer on the front of the
left ventricle, passing into one of the
larger papillary muscles, and derived
from the posterior superficial fibres, which
have entered the whorl of the apex ante-
riorly ; the different degree of obliquity
and other changes of direction of the
fibres is shown in these several layers ; c, c, between these letters and numbers is the
anterior coronary or interventricular groove, in which superiorly the greater part of the
fibres of the superficial layer is seen to cross from right to left ; in the remaining part of
the groove, which is dissected, part of the fibres from both ventricles is seen to turn
backwards towards the septum ; d t the pulmonary artery cut short ; e, the first part of
the aorta.
and the roots of the great arteries. The only fibres which come in contact with
those structures are the fibres of the superficial layer, where they dip in to be con-
tinuous with those of the deepest layer ; and even these for the most part exhibit, on
careful dissection, no breach of continuity of muscular fibres, but are merely bound
down by white tissue penetrating between the fasciculi ; a small portion, however, of
the muscular fibres which surround the auriculo-ventricular orifices become continuous
with the segments of the valves and with chordae tendineae, and through them with
the musculi papillares, the fibres of which belong chiefly to the innermost layer.
Some fibres, especially those belonging to the superficial layers, and more especially
upon the posterior surface of the heart, pass round and enclose both ventricles ; others,
especially in front, may be considered to belong to one ventricle only. Thus the
anterior superficial fibres of the right ventricle, in descending from the right to the
320
THE HEART.
left of the heart, pass in part across the anterior longitudinal groove, covering partially
the coronary vessels, and in part dip into the groove and ascend obliquely upon the
right side of the septum. The anterior fibres of the left ventricle are derived in part
from those arising from the roots of the great vessels, in part from those crossing the
coronary groove from the right, and in part they come out from the left surface of the
septum, into which they dip in front like those of the right ventricle ; those of the
anterior fibres of the left ventricle which are near the apex pass spirally round this
part to enter the whorl posteriorly, while the posterior set of superficial fibres, turning
round the apex with a similar spiral, arrive in front and there enter the vortex.
These fibres thus carried into the interior ascend upon the posterior and anterior
Fig. 239.
Fig. 239. VIEW OF THE FIBRES OF
THE SHEEP'S HEART, DISSECTED AT
THE APEX TO SHOW THE " VoilTEX "
IN WHICH THE FIBRES ENTER THE
APEX IN TWO SETS FROM THE Ex-
TERNAL LAYER (from Pettigrew).
a, a, anterior fibres entering the
apex of the left ventricle posteriorly
at Z; c, c, posterior fibres entering
the apex anteriorly at d.
internal surfaces of the left ven-
tricle, forming the almost longi-
tudinal innermost layer of fibres,
and contribute to form the columnse carnece and musculi papillares. Their direction,
as they ascend internally, is nearly the opposite of that in which they made their
descent externally.
The direction of the fibres in the successive layers gradually changes as we proceed
from without inwards ; for example, on the front of the right or left ventricle it is
at first very oblique from right to left of the heart, or indeed in some parts almost
longitudinal from base to apex,* it then becomes less and less oblique, until in the
middle layer, which is also the thickest, it is transverse ; the obliquity being now
resumed and gradually increasing, the direction is changed to that from right to left
of the heart and from apex to base upwards, until at last in the interior it is extremely
oblique, or nearly longitudinal.
Fig. 240.
Fig. 240. DISSECTION OF THE VEN-
TRICLES OF THE SHEEP'S HEART,
VIEWED FROM BEHIND, A PART OF THE
POSTERIOR WALL BEING REMOVED TO
snow A DISSECTION OF THE FIBRES OF
THE SEPTUM AT A SIMILAR DEPTH
(from Pettigrew). |
a, the superficial layer of fibres of the
right ventricle ; b, the same of the left
ventricle at the base arid apex pos-
teriorly ; a 4 , the fourth or middle layer
of fibres of the right ventricle exposed ;
Z> 4 , the same layer of the left ventricle ;
c 4 , the same of the septum, showing the
fibres of that layer continued forward
from those of the left ventricle.
It is only the three outer layers and part of the fourth layer which are distributed
round both ventricles ; the three internal layers belong solely to each ventricle.
The septum consists of three sets of fibres, viz., 1, those belonging to the right
ventricle : 2, those belonging to the left ; and 3, those common to both ventricles.
The difference of thickness of the walls of the right and left ventricles, which is so
The direction is less longitudinal in the human heart than in that of the sheep.
VESSELS AND NERVES SIZE AND WEIGHT. 321
remarkable in the adult, does not exist at an early period in the foetus. An examina-
tion of the foetal heart, therefore, shows a much greater similarity in the mode of
arrangement of the layers of fibres in the walls of the two ventricles than might be
supposed from the examination of the adult.
It is to be observed, in conclusion, that Pettigrew's observations were made almost
exclusively upon the hearts of animals. No doubt many circumstances are nearly
similar in the human heart, but it is still desirable that a fuller examination of the
structure of the human heart should be made, and more especially that this subject
should be investigated in connection with its development.
(C. F. Wolff, De ordine fibrarum Muscularium Cordis ; Act. Acad. Petropol. 1780
1792. Gerdy, Rech. &c. d' Anatomic, Paris, 1823. J. Reid, Art. "Heart/' in
Cyclop, of Anat. and Physiol. Searle, Art. " Fibres of the Heart," in the same.
J. Pettigrew, in Philos. Trans. 1864.)
VESSELS AND NERVES.
The blood-vessels and nerves of the heart will only be shortly noticed in this place,
as a fuller description of them will be given along with those parts of the vascular
and nervous systems from which they respectively take their origin.
Vessels. The substance of the heart receives its blood through the two coronary
arteries, which arise respectively from the two anterior aortic sinuses of Valsalva.
The coronary veins terminate in the right auricle. Besides the great cardiac or
coronary vein, and another principal branch, there are two smaller orders of veins
opening separately into the right auricle. The stems and larger divisions of these
vessels run principally in the great transverse and longitudinal grooves of the heart ;
from these grooves and other parts of the external surface the smaller branches
penetrate into every part of the muscular substance.
Nerves. The nerves given off by the cardiac plexuses, appear rather small in com-
parison with the bulk of the heart ; they are derived partly from the cerebro-spinal
and partly from the sympathetic system, more especially from the pneumogastric nerve,
ancl from the cervical and superior dorsal ganglia of the sympathetic nerve. Besides
the larger ganglia in the cardiac plexuses at the base of the heart, the nerves present
minute ganglia at different points along their course in its substance, which have been
figured and described by Remak. The nerves course obliquely downwards on the
ventricles of the heart, decussating with the superficial fibres, between which and the
pericardium are situated their main branches and the ganglia of Remak. (Remak ;
Froriep's Notizen, 1838, p. 137; and Muller's Archiv. 1844, p. 463, taf. xii.)
WEIGHT AND DIMENSIONS OF THE HEART.
The size and weight of the heart, the thickness of its walls, the capacity of its
several cavities, and the width of its great orifices, have been made the subject of
extensive observation, more especially with the view to determine some standard
dimensions with which to compare the deviations occurring in disease.
Size. It was stated by Laennec, as the result of his experience, that the heart in
its natural condition was about equal in size to the closed hand of the individual.
It is about five inches long, three and a half in its greatest width, and two and a
half in its extreme thickness from the anterior to the posterior surface ; but linear
measurements of a flaccid organ like the heart must be subject to so many accidental
variations as to render them of little value.
Weight. The average weight of the heart in the adult is also subject to consider-
able variation, ranging between rather wide limits, which depend on the general
weight of the body and on the sex.
Its mean weight has been variously stated by different authors, as from 7 oz. up
to 10 oz. ; but, according to tables published by Reid, the average weight in the
adult male is as high as 11 oz., and in the female as 9 oz. ; while according to Peacock
the average of the male is 9| oz., and that of the female 9 oz.
The weight of the heart maintains some general proportion to that of the body.
According to Tiedemann this is about 1 to 160; by Clendinning it was found to be
1 to 158 in males, and 1 to 149 in females ; and by Reid to be 1 to 169 in a series of
thirty-seven males, and 1 to 176 in twelve females ; but in the healthy males dying
suddenly the ratio was as 1 to 173.
322 THE HEART.
It was shown by Clendinning that the heart continued to increase in weight up to
an advanced period of life, but at a comparatively slower rate subsequently to the
age of twenty-nine years. Subjoined is a tabular statement of some of the average
results derived from the observations of these authors.
CLENDINNING. REID. PEACOCK.
Weight in oz. Weight in oz. and drachms.
Age in years. Males. Females. Age in years. Males. Females. Males. Females.
15 to 29 ... 8| ... 81 16 to 20 ... 8 10 ... 6 13 8 2 ... 8 1|
30 50 ... 91 ... 81 20 30 ... 10 4 ... 8 9 01 ... 8 10}
50 60 ... 101 ... 8 30 40 ... 10 8 ... 9 3 97 ... 8 13|
60+ ... 101 ... 8 40 50 ... 11 7 ... 9 8 8 11 ... 9 3
50 60 ... 11 10 ... 9 14 9 12 ... 9 71
60 70 ... 12 6 ... 9 5 10 13| ... 7
70 (- ... 12 6 ... 9 6
Entirely in accordance with these observations upon the increase of the heart's
weight according to age, it has been found by Bizot that this organ continues to enlarge
in all its dimensions as life advances, viz., in the length, breadth, and thickness
of its walls. The greatest increase was detected in the substance of the left ventricle,
and the ventricular septum. (Reid, in the Lond. and Edin. Monthly Journal of Med.
Science, April, 1843; T. B. Peacock, in the same journal, in 1846, and reprinted
separately, with additional observations, in 1854 ; Clendinning, in the Medic. Chir.
Transact., 1838 ; Bizot, M6m. de la Soc. M6dic. d'Observation de Paris, torn. i.
p. 262. 1836.)
Capacity of the auricles and ventricles. To determine with precision the absolute
and relative capacities of the four cavities of the heart, as they exist during life, is
impossible ; and their capacity is so much influenced by their different states of
distension, and also by the different degrees of contraction of their muscular walls at
the moment of death, that no constant numerical relation in this respect can be
looked for between them. Hence the most opposite statements prevail, especially
with regard to the size of the ventricular cavities.
The auricles are generally admitted to be rather less capacious than the ventricles.
The right auricle is also said to be larger than the left, in the proportion of 5 to 4.
(Cruveilhier.)
The capacity of the left ventricle has been stated by different anatomists as
variously as at 1| fluid ounces and 4 oz. ; it probably does not exceed 2 oz.
The right ventricle is asserted by some to be larger than the left ; by others (Lower,
Sabatier, Andral) the two are stated to have an equal capacity ; Cruveilhier, j udging from
the effect of injections, has found the left to be the larger of the two. In the ordinary
modes of death, the right ventricle is always found more capacious than the left,
which is probably owing to its being distended with blood, in consequence of the
cessation of the circulation through the lungs : the left ventricle, on the other hand,
is found nearly empty, and thus becomes more fully contracted. There are reasons
for believing, however, that during life scarcely any difference of capacity exists
between the two cavities.
Size of the ventricular openings. The right auriculo-ventricular opening, and the
orifice of the pulmonary artery, are both found to be somewhat larger after death
than the corresponding openings on the left side of the heart. Their circumference
is thus stated by Bouillaud. (Traite des Malad. du Coeur, torn. i. p. 52. Paris, 1835.)
Inches and Lines.
Max. Med. Min.
Auriculo-ventricular orificesj^ ; J ^ * J
Arterial orifices j Right (Pulmonary) 210 27 26
' | Left (Aortic) 28 28 24
According to Peacock's most recent observations, the following (omitting the
DEVELOPMENT OF THE HEART.
323
fractions of lines) are the average dimensions of these orifices in adult males and
females, between the ages of 20 and 60 years :
Auriculo-ventricular orifices
Right
Arterial orifices .
( Right (Pulmonary)...
' (Left (Aortic) .........
Males. Females.
Inches and Lanes.
46 40
37 3 10
34 33
30 2 10
DEVELOPMENT OF THE HEART AND GBEAT BLOOD-VESSELS.
The Heart. The heart first appears as an elongated sac or dilated tube lying at
the fore part of the embryo, having two veins connected with it behind, and a
large arterial trunk proceeding from it in front. This tube exhibits rhythmic con-
tractions of its walls from a very early period. Its form is at first symmetrical, but
soon it becomes curved or bent upon itself like a horse-shoe, and projects on the
ventral aspect of the body towards the right side.
Fig. 241.
Fig. 241. VIEWS OF THE ANTERIOR OR
CEPHALIC HALF OF THE EMBRYO-CHICK
FROM THE ABDOMINAL SURFACE, SHOW-
ING THE HEART IN THE EARLIEST
STAGES OF ITS FORMATION (after Re-
mak). Magnified about twenty times.
A, embryo after about twenty-eight
or thirty hours of incubation ; B,
after about thirty-six hours of incuba-
tion ; a, placed on the anterior cerebral
vesicle; b, the primitive cervical ver-
tebrae ; c, c, the cephalic fold of the ger-
minal membrane ; 1, 1, primitive veins
entering the auricle ; 2, 3, in A, the
primitive and simple sac or short tube of
the heart ; in B, 2, the auricular part ;
3, the ventricular part beginning to bulge
or be bent to the side and dilate ; 4,
the anterior part of the tube which be-
comes the aortic bulb.
As this bending increases the venous end approaches the arterial, and at the same
time the tube, which progressively increases in size and in the thickness of its walls,
becomes divided by two slight constrictions into three compartments, opening suc-
cessively into each other. The first, next to the veins, is the auricular portion, the
middle one is the ventricular, and the last, which is the primitive arterial trunk,
is named the bulbus arteriosus.
The auricular portion becomes placed behind the ventricular compartment, and
relatively to that cavity considerably enlarged. Moreover, two little pouches appear
upon it, one at each side, which form the future auricular appendages. The walls of
the ventricular portion are already thicker than the rest.
The next series of changes consists in the gradual subdivision of the single auricle,
ventricle, and arterial bulb, each into two compartments, to form the right and left
auricles, the right and left ventricles, and the pulmonary artery and aorta; and these
changes are accompanied by an alteration in the position of the parts with relation to
the body, the ventricular portion now lying transversely, so as to bring that portion
which is afterwards to form the apex towards the left side.
This subdivision commences first in the single ventricular portion of the heart.
A small notch appears externally to the right of the apex, which goes on increasing
in depth for some weeks, and then is again gradually obliterated. In the meantime,
about the fourth or fifth week, a septum begins to rise up internally from the right side
of the heart, at a little distance from the apex 'and from the anterior wall of the cavity,
and proceeds in the direction of the base, towards the arterial bulb, and about the
eighth week is complete. Traces of the subdivision of the auricular portion com-
324
THE HEART.
Fig. 242. DIAGRAMMATIC OUTLINES OF THE HEART AND FIRST ARTERIAL VESSELS
OF THE EMBRYO, AS SEEN FROM THE ABDOMINAL SURFACE.
A, at a period corresponding to the 36th or 38th hour of incubation in the chick ;
B, and C, at the 48th hour of incubation ; 1, 1, primitive veins ; 2, auricular part of the
heart ; 3, ventricular part ; 4, aortic bulb ; 5, 5, the primitive aortic arches, and their
continuation as descending aorta ; these vessels are still separate in their whole extent in
A, but at a later period, as shown more fully in C, have coalesced into one tube in a part
of the dorsal region ; in B, below the upper 5, the second aortic arch is formed, and
farther down the dotted lines indicate the position of the succeeding arches to the number
of five in all ; 5', 5', the continuation of the main vessels in the body of the embryo ;
6, 6, the omphalo-mesenteric arteries passing out of the body of the embryo into the
vascular area of the germinal membrane.
mence early in the form of a slight constriction on the outer surface, which marks
off the future auricles, the left being at first the smaller of the two; but the
auricular septum is not begun until after that of the ventricles is completed. About
Fig. 243. Fig. 243. HUMAN EMBRYOES
AT DIFFERENT EARLY STAGES
OF DEVELOPMENT, SHOWING
THE HEART IN ITS TUBULAR
CONDITION.
A, upper half of the body of
a human embryo of three weeks,
viewed from the abdominal
side (from Costo) ; a, frontal
plate ; 6, vertebrae, on which
the primitive aortse are lying ;
3, the middle of the tube of the
heart, below it the place of en-
trance of the great veins, above
it the aortic bulb.
B, lateral view of a human
embryo more advanced than that
last referred to, and somewhat imperfectly developed (from A. Thomson) ; a, the frontal
part of the head ; &, the vertebral column ; v, the wide communication of the umbilical
vesicle or yolk-sac with the intestine ; u, communication with the allantois or urachus ; 2,
auricular part of the heart connected with the veins posteriorly ; 3, ventricular part of
the bent tube ; 4, the aortic bulb ; near the extremities of the tube the divided peri-
cardium is seen.
DEVELOPMENT OF THE HEART AND VESSELS.
325
the ninth week it appears, growing from above and behind downwards and forwards,
and at length comes to meet and coalesce below with the rising edge of the inter-
Fig. 244. SHOWS THE POSITION AND Fig. 224.
FORM OF TDE HEART IN THE HCMAN
EMBKTO FROM THE FOURTH TO THE SIXTH
WEEK.
A, upper half of the body of a human
embryo said to be four weeks old (from
Kolliker after Coste) ; B and C, anterior
and posterior views of the heart of a human
embryo of six weeks (from Kolliker after
Ecker) ; a, frontal lappet ; 6, mouth ; c,
below the lower jaw and in front of the
second and third branchial arches ; d,
upper limb; e, liver; /, intestine cut
short ; 1 , superia vena cava ; 1', left
superior cava or brachio-cephalic connected
with the coronary vein ; 1 ", opening of the
inferior vena cava; 2, 2', right and left
auricles ; 3, 3', right and left ventricles;
4, aortic bulb.
ventricular septum. The interauricular sep-
tum, however, remains incomplete during
intrauterine life, and leaves an opening in the middle, which forms the foramen ovale.
The farther steps in the separation of the auricles are connected with the changes
which take place at the entrances of the great veins. There are now three large vessels
terminating in the auricular extremity of the heart ; of these two correspond with
the superior and the inferior vena cava, and the third is the great coronary vein.
At first, after the interauricular septum is partly formed above, the inferior cava
opens directly into the left auricle, which is the smaller of the two ; but about the
twelfth week a septum, the valve of the foramen ovale, which afterwards forms the
floor of the fossa ovalis, rises up on the left side of the entrance of the vein, which
thus comes to open into the right auricle ; whilst at the same time the separation of
the two auricles is also rendered more complete by the gradual advance of the valve
over the foramen ovale, leaving, however, the passage open until after birth.
Another valvular fold is developed at an early period on the right and anterior
border of the orifice of the inferior cava, between it and the auriculo-ventricular
orifice ; this is the Eustachian valve. It appears to continue the opening of the
inferior cava towards the upper margin of the foramen ovale, and directs the blood
of the vein through that passage.
The left auricle has at first no connection with the pulmonary veins. The manner
in which this connection is afterwards established has not yet been ascertained.
Originally the heart is composed of a mass of nucleated cells, similar in character
to those which primarily constitute the other organs of the body. Muscular tissue is
subsequently formed from these cells ; but the rhythmic contractions commence and
proceed for some time, whilst the heart is yet composed of cells, and before the mus-
cular fibres have been developed.
The great vessels. At first the bulbus arteriosus is divided into two arches, which
pass upwards and outwards one on each side, then turn downwards and form a right
and left root of the aorta, which are at first separate, but afterwards unite behind
the heart and in front of the vertebral column to form the single stem of the descend-
ing aorta. The distance soon elongates between those arches and the arterial bulb,
and four other pairs of arches appear in series from above downwards, passing
outwards from the vessel which ascends to the first arch, and opening into that
which descends from it. Thus there are on each side five arches, an internal or
anterior trunk uniting the origins of the arches, and an external or posterior trunk
uniting their terminations, and continued into one of the roots of the aorta. These
vascular arches are placed each in one of the branchial processes of the dorsal plates
(p. 64), but it is to be noted that the whole five arches do not co-exist; for the highest
326
THE HEART.
disappear before the last are developed. This arrangement of blood-vessels, together
with the originally single condition of the heart, corresponds to a certain extent with
the permanent condition of the heart and branchial arteries in fishes ; with this
difference as regards the vascular arches in the human foetus and that of mammals,
birds, and scaly reptiles, that they never present any farther branchial subdivision.
As the interventricular septum is approaching the base of the heart, that is, about
the seventh or eighth week, the arterial bulb becomes also divided by an internal
partition, meeting from opposite sides, into two vessels, which are slightly twisted on
each other, and are so adjusted as to become connected, the anterior with the right
and the posterior with the left ventricle : these vessels afterwards constitute the com-
mencement of the pulmonary artery and of the aorta. A furrow subsequently, begin-
ning on the outside, completes the separation into two vessels.
Whilst the arterial bulb is thus converted into the commencement of the pulmonary
artery and. aorta, the five vascular arches arising from it undergo a metamorphosis,
by which the permanent aorta with the brachio-cephalic vessels and the pulmonary
arteries are formed. The general results of this change have been observed by
several ernbryologists, but it has not yet been made out with certainty in all its
details.
It is generally admitted, however, that the fourth arch on the left side (counting
from above), which receives blood from the aortic division of the bulb, is persistent,
and, continuing to enlarge, eventually becomes the arch of the aorta. The fourth
arch on the right side, as well as the first, second, and third arches on both sides,
are obliterated to a greater or less extent, while certain portions of them, remaining
pervious and connected with the aortic arch, appear to form the commencement of the
great vessels rising from it.
Both the arches of the fifth pair were held by Baer to be connected with the
Fig. 245. Fig. 245. DIAGRAM OP THE AORTIC OR
BRANCHIAL VASCULAR ARCHES OF THE
MAMMAL WITH THEIR TRANSFORMATIONS
GIVING RISE TO THE PERMANENT ARTERIAL
VESSELS (according to Eathke).
A, P, primitive arterial stem or aortic
bulb, now divided into A the ascending
part of the aortic arch, and P the pul-
monary ; a, the right ; a', the left aortic
root ; A', the descending aorta. On the
right side 1, 2, 3, 4, 5, indicate the five
branchial primitive arterial arches ; on the
left side, I, II, III, IV, the four branchial
clefts, which, for the sake of clearness, have
been omitted on the right side. It will be
observed, that while the fourth and fifth
pairs of arches rise from the part of the
aortic bulb or stem, which is at first un-
divided, the first, second, and third pairs
are branches above c, of a secondary stem
on each side. The permanent systemic
vessels are represented in deep shade, the
pulmonary arteries lighter ; the parts of
the primitive arches, which have only a
temporary existence, are drawn in outline
only, c, placed between the permanent common carotid arteries ; ce t the external
carotid arteries ; ci, ci' the right and left internal carotid arteries ; s, the right sub-
clavian rising from the right aortic root beyond the fifth arch ; v, the right vertebral
from the same opposite the fourth arch ; v', s', the left vertebral and subclavian arteries
rising together from the left or permanent aortic root opposite the fourth arch ; P, the
pulmonary arteries rising together from the left fifth arch ; d, the outer or back part of
the left fifth arch, forming the ductus arteriosus j pn, pn', the right and left pneumo-
gastric nerves, descending in front of the aortic arches, with their recurrent branches
represented diagrammatically as passing behind, with a view to illustrate the relations of
these nerves respectively to the right subclavian artery and the arch of the aorta and
ductus arteriosus.
p-n
THE FCETAL HEART.
327
pulmonary division of the bulb, and to send ramifications into the lungs, so as to form
the right and left branches of the pulmonary artery respectively : the farther or distal
portion of the right arch being obliterated, while the corresponding part of the left
side continued open, as the ductus arteriosus, until birth. According to this view,
the third arch on each side is persistent as the subclavian artery, and the external trunk
above this remains as the vertebral artery, and the internal as the carotid ; while the
internal trunk between the third and fourth arches of the right side becomes the
innominate artery. In so far as it applies to birds and some reptiles, this view may be
correct. But a different view of the metamorphosis, as it occurs in mammalia and
man, has more recently been presented by Rathke, which has been adopted by
Kolliker and others, and probably is more consistent with truth. According to
Rathke, in man and mammalia one arch only, viz. the left fifth, is concerned in the
formation of the pulmonary arteries; and the fifth arch of the right side is entirely
obliterated. From the fifth left arch a branch is given off, which, together with
the proximal part of the arch, forms the pulmonary artery, and which divides
into the primary branches for the right and left lung, the distal part of the arch being
converted, as according to Baer's theory, into the ductus arteriosus. The fourth arch
of the right side, according to Rathke, forms the commencement of the right subclavian
artery ; a branch is given off opposite the external extremity of the fourth arch on
both sides, which forms on the right side the remainder of the right subclavian,
and on the left the whole of that artery ; the vertebral arteries are derived from
the subclavians externally to the system of arterial arches ; the internal trunks in
their extent between the third and fourth arches remain as the common carotids, and
-in the remainder of their extent form the external carotids, while the third arches
and the external trunks above them are converted into the internal carotid arteries.
(Baer, Entwicklungsgeschichte, 1839 ; Rathke, Untersuchungen uber die Aortenwurzeln,
&c., Vienna, 1857, and Muller's Archiv. 1843, p. 276; A. Thomson, Edin. New
Philos. Journal, 1830-31, and Edin. Med. and Surg. Journ., No. 140 ; Ecker, Icones
Physiologicae ; Bischoff's works ; Kolliker, Entwicklungsgeschichte. 1861.)
Fig. 246.
PECULIARITIES OF THE F(ETAL HEART AND G REAT VESSELS. F<ETAL
CIRCULATION.
Position. The foetal heart, even after all its parts are formed, continues to be
placed vertically in the thorax until about the fourth month, when the apex begins
Fig 246. VIEW OP THE FRONT AND RIGHT
SIDE OP THE FOETAL HEART, AT FOUR
MONTHS, THE RIGHT AURICLE BEING LAID
OPEN (from Kilian).
a, the right auriculo-ventricular opening ;
&, a probe passed up the vena cava inferior
and through the foramen ovale into the left
auricle ; c, vena cava inferior ; e, Eustachian
valve ; v, valve of the foramen ovale ; s, s',
vena cava superior.
to turn towards the left side, so as to give
it an oblique position.
Size. As compared with the body, the
heart is very much larger in the early
foetus than at later periods or subsequently
to birth. At one time, indeed, it occupies
nearly the whole thoracic cavity. At the
second month the proportion of its weight to
that of the body is said by Meckel to be 1
to 50 ; but the ratio becomes gradually re-
duced to that of 1 to 120 at birth. In the
adult the average is about 1 to 160.
For a long period the auricular portion is larger than the ventricular, and the right
auricle is more capacious than the left; but towards birth these peculiarities disappear,
328
THE HEAET.
and the ventricular portion becomes the larger part of the heart. As to the ventricles
themselves, the right is at first the smaller ; afterwards it becomes the larger of the
two, and at birth their size is about equal. In the right ventricle the infundibulum
is at first less marked than afterwards.
Structure. For a time the walls of the ventricles are, comparatively speaking,
very thick, and the thickness of both is nearly the same. In approaching the full
period, however, the left begins to be the thicker of the two. But the two chief
differences in the internal structure of the foetal heart from that of the adult are the
communication which exists between the two auricles by the foramen ovale, and the
large size of the Eustachian valve.
The large oval orifice named the foramen ovale is placed at the lower and back
part of the auricular septum, and is said to attain its greatest size at the sixth month.
It becomes gradually occluded by a valvular fold already alluded to, which ascends
from below and behind, and rises up on the left side of the rim of the foramen ovale.
This rim becomes continuous at the sides with the valve, but above its free margin,
which is concave and turned upwards, the foramen is left open. At length the valve
passes for some distance beyond the upper part of the foramen; and still, owing to its
position on the left side of the opening, it permits the passage of blood from the right
to the left auricle. In the reverse direction, however, it closes the opening, and no
blood can pass.
Fig. 247.
Fig. 247. VIEW OF THE POSTERIOR AND LEFT
SURFACE OF THE HEART OF A FffiTUS OF FOUR
MONTHS, THE LEFT AURICLE BEING OPENED
(from Kilian).
a, left auriculo-ventricular orifice ; c, inferior
vena cava, through which a probe b, is passed
from below, and thence by the foramen ovale
into the left auricle ; e, left auricular appendage
laid open ; o, valve of the foramen ovale seen
to be attached to the left side of the annulus
ovalis of the septum.
The pulmonary artery of the foetus, in
leaving the right ventricle, first gives off
the branch to the right lung, and then
appears to divide into its left branch and
the short but wide tube named ductus
arteriosus. This vessel, which is nearly as
wide as the pulmonary artery itself, is of the
thickness of a goose-quill at the time of birth,
and about half an inch long. It conducts the
chief part of the blood of the right ventricle
into the aorta, which it joins obliquely within
the termination of the arch, a little beyond
the origin of the left subclavian artery.
Besides the usual branches of the descending aorta intended to supply the abdominal
viscera and the lower limbs, two large vessels, named hypogastric or umbilical arteries,
are prolonged from the common iliacs, and, passing out of the abdomen, proceed along
the umbilical cord, coiling round the umbilical vein, to reach the placenta. The com-
mencement of each of these vessels afterwards forms the trunk of the corresponding
internal iliac artery, and, from their size, they might be regarded in the foetus as the
continuations of the common iliac arteries into which the aorta divides. From the
placenta the blood is returned by the umbilical vein, which, after entering the
abdomen, communicates by one branch with the portal vein of the liver, and sends
another, named ductus venosus, to join the vena cava inferior, as will be more fully
described in the account of the vessels of the liver.
Course of the blood in the foetus. The right auricle of the foetal heart receives its
blood from the two vense cavee and the coronary vein. The blood brought by the
superior cava is simply the venous blood returned from the head and upper half of
THE FCETAL CIRCULATION. 329
the body; whilst the inferior cava, which is considerably larger than the superior,
conveys not only the blood from the lower half of the body, but also that which is
sent back in a purified state from the placenta through the umbilical vein. This
latter stream of blood reaches the vena cava inferior, partly by a direct passage the
duetus venosus, and partly by the hepatic veins after circulating through the liver in
the venae portse.
The blood of the superior vena cava, descending in front of the Eustachian valve,
and mixed with a small portion of that from the inferior cava, passes on into the
right ventricle, and is thence propelled into the trunk of the pulmonary artery. A
small part of it is then distributed through the branches of that vessel to the lungs,
and returns by the pulmonary veins to the left auricle ; but by far the larger part
passes through the duetus arteriosus into the aorta, entering that vessel beyond the
place of origin of the arteries of the head and upper limbs, and, mixed probably
with a small quantity of the blood flowing along the aorta from the left ventricle,
descends partly to supply the lower half of the body and the viscera, but principally
to be conveyed along the umbilical arteries to the placenta. From all these parts it
is returned by the vena cava inferior, the venae portae, and the umbilical vein ; and,
as already noticed, reaches the right auricle through the trunk of the inferior cava.
The blood of the inferior vena cava is only in small part distributed with that of
the superior cava ; by far the larger portion, directed by the Eustachian valve through
the foramen ovale, flows from the right into the left auricle, and thence, together with
the small quantity of blood returned from the lungs by the pulmonary veins, passes
into the left ventricle, whence it is sent into the arch of the aorta, to be distri-
buted almost entirely to the head and upper limbs. A small portion of it, how-
ever, probably flows on into the descending aorta and joins the large stream of blood
from the duetus arteriosus. From the upper half of the body the blood is returned
by the branches of the superior cava to the right auricle, from which its course has
been already traced.
Sabatier was of opinion that no mixture of the two streams of blood from the two
venae cavae took place in the right auricle, but that all the blood of the inferior cava
passed into the left auricle and ventricle, whilst that of the superior cava reached the
right ventricle. He thought, however, that the two kinds of blood were intermixed at
the junction of the duetus arteriosus with the aorta. The entire separation of the two
streams of blood of the venae cavaa, as supposed by Sabatier, is not generally admitted
in the mature foetus ; but there is reason to believe that it does take place in earlier
stages. In fact, the inferior cava, as already mentioned, at first opens into the left
auricle, and must therefore convey its blood immediately into that cavity. As the
foetus approaches maturity, more and more of the blood of the inferior cava joins the
stream from the superior cava ; and, indeed, the course of the blood, and the relative
position of the veins, as well as other original peculiarities of the foetal heart, become
gradually altered, to prepare the way as it were for the more important changes
which take place at birth. It seems also probable that very little of the blood pro-
pelled from the left ventricle passes into the descending aorta beyond the duetus
arteriosus.
From the preceding account of the course of the blood in the foetus, it will be seen
that, whilst the renovated blood from the placenta is principally conveyed to the
upper or cephalic half of the foetus, the lower half of the body is chiefly supplied with
the blood which has already circulated through the head and upper limbs, exhibiting
in this a certain analogy with the mode of circulation in the turtle and various other
reptiles. The larger portion of this latter stream of blood, however, is again sent out
of the body to be changed in the placenta. This duty is principally performed by
the right ventricle, which after birth is charged with an office somewhat analogous, in
having to propel the blood through the lungs. But the passage of the placental blood
is longer than that of the pulmonary, and the right ventricle of the foetus, although
probably aided by the left in the placental circulation, also takes a large share in the
systemic circulation through the lower half of the body ; and this, perhaps, may be
the reason why the right differs less in thickness from the left ventricle in the foetus
than in the adult.
Changes after birth. The immediate changes which take place at birth consist of
the sudden stoppage of the placental circulation and the simultaneous commence-
330
THE HEART.
PULMONARY VESSELS. 331
Fig. 248. SEMI-DIAGRAMMATIC VIEW OF THE ORGANS OP CIRCULATION IN THE Forrus
FROM BEFORE, (modified from Luschka and from Nature), f
a, front of the thyroid cartilage ; 5, right side of the thyroid body ; c, trachea ; d t
surface of the right lung turned outwards from the heart ; e, diaphragm below the apex
of the heart ; /, right lobe of the liver, dissected to show ramifications of the portal and
hepatic veins ; /', the middle part and left lobe of the liver in the same manner, showing
branches of the umbilical veins and ductus venosus ; g, right, c/, left kidney ; g", supra-
renal bodies ; h, right, h', left ureter ; r, portion of the small intestine turned towards
the side, to show the veins from it going to the portal vein ; k, urinary bladder ; Z, is
placed below the umbilicus, which is turned towards the left of the fetus, and points
by a line to the urachus ; m, rectum, divided and tied at its upper part.
A, A, right auricle of the heart opened to show the foramen ovale : a probe, intro-
duced through the large divided right hepatic vein and vena cava inferior, is seen passing
through the fossa ovalis into the left auricle : at the lower part of the fossa ovalis is seen
the Eustachian valve, to the right and inferiorly the auriculo-ventricular orifice ; B, the
left auricular appendix ; (7, the surface of the right ventricle ; D, placed on the inner
surface of the left lung, points to the left ventricle.
1, ascending part of the arch of the aorta; I 7 , back part beyond the ductus arteriosus ;
1", abdominal aorta ; 2, stem of the pulmonary artery; 2', the place of division into
right and left pulmonary arteries and root of the ductus arteriosus : the left pneumo-
gastric nerve is seen descending over the arch of the aorta ; 3, superior vena cava ; 3',
right, 3", left innominate vein ; 4, stem of the inferior vena cava, between the junction
of the hepatic vein and the right auricle ; 4', continuation of the vena cava inferior below ;
5, umbilical vein within the body of the foetus ; 5 x , without the body, in the umbilical
cord ; 5', 5', ductus venosus ; between 5 and 5', the direct branches of the umbilical vein
to the liver ; 5", 5'', hepatic veins, through one of which a probe is passed into the fossa
ovalis and through the foramen ovale ; 6, vena portae ; 6', its left branch joining the
umbilical vein ; 6", its right branch ; 7, placed on the right iliac vein, points to the right
common iliac artery ; 7', left common iliac artery ; 8, right, 8', left umbilical arteries
coming from the internal iliac arteries ; 8 x , umbilical arteries without the body, in the
umbilical cord; 9, 9', external iliac arteries; 10, placed below the right renal vessels ;
11, inferior mesenteric artery, above the root of which are seen the two spermatic arteries.
ment of an increased flow of blood through the lungs, which then perform their office
as respiratory organs. The foramen ovale, the ductus arteriosus, the ductus venosus,
and the umbilical vessels, all parts peculiar to the foetus, are gradually closed, and the
right and left cavities of the heart thenceforth cease to communicate directly with
each other. According to Bernt, the ductus arteriosus begins to contract imme-
diately after several inspirations have taken place : in three or four days he some-
times found it closed; on the eighth day it was obliterated in one half the cases
examined, and on the tenth day in all. The foramen ovale appears to continue open
a little longer, and it sometimes remains more or less so throughout life, as already
stated. The umbilical arteries, the umbilical vein, and the ductus venosus, shrink and
begin to be obliterated from the second to the fourth day after birth, and are gene-
rally completely closed by the fourth or fifth day.
PULMONARY VESSELS.
PULMONARY ARTERY AND VEINS.
The pulmonary artery is a short wide vessel, which carries the dark blood
from the right side of the heart to the lungs. Tt arises from the infundi-
bulum or conus arteriosus of the right ventricle, and passes for the space of
nearly two inches upwards, and at the same time backwards and to the left
side, to reach the concavity of the aortic arch, where it divides into its
right and left branches. The mode of attachment of the pulmonary artery
to the base of the ventricle has already been fully noticed. At each side
of its commencement is the corresponding coronary artery springing from
the aorta, and close to its sides are the two auricular appendages. It
is at first in front of the aorta, and conceals the origin of that vessel ;
but higher up, where it lies in front of the left auricle, it crosses to the
left side of the ascending aorta, and is finally placed beneath the transverse
z 2
332 THE ARTERIES.-AORTA.
part of the arch. The pulmonary artery and the aorta are united together
by connective tissue and by the serous layer of the pericardium, which for
the space of about two inches forms a single tube around both vessels.
Rather to the left of its point of bifurcation it is connected to the under
side of the aortic arch by means of a short fibrous cord, which passes
obliquely upward?, backwards, and to the left. This is the remains of the
ductus arteriosus, a large vessel peculiar to the foetus, which has been
already described.
The two branches of the pulmonary artery. The right branch, longer and
somewhat larger than the left, runs almost transversely outwards behind
the ascending aorta and the superior vena cava into the root of the right
lung, where it immediately begins to divide in the usual manner of arteries.
The left branch, shorter than the right, passes horizontally in front of the
descending aorta and left bronchus into the root of the left lung, to undergo
its ramification.
The right and left pulmonary arteries, at the root of the lung, both lie
in front of the bronchus and behind the veins. On the right side the
bronchus is highest and the veins lowest, while on the left side the bronchus
sinks to a level between the artery and veins.
Pulmonary Veins. The pulmonary veins, which convey the red blood
back from the lungs to the left side of the heart, ultimately converge into
four short venous trunks, which are found, two on each side, in the root of
the corresponding lung. The two veins of the right side, which are longer
than those of the left, pass below the right pulmonary artery, and behind
the superior vena cava, the right auricle, and the aorta, to enter the left
auricle. Not unfrequently a third smaller vein exists on the right side.
The two left pulmonary veins run a shorter course to reach the auricle,
passing in front of the descending aorta.
SYSTEMIC VESSELS.
ARTERIES.
THE AORTA.
The aorta, the large main trunk of the systemic arteries, is situated partly
within the thorax and partly in the abdomen. It commences at the left
ventricle of the heart, and, after arching over the root of the left lung,
descends in front of the vertebral column, and, passing through the diaphragm
into the abdominal cavity, ends opposite the fourth lumbar vertebra, by
dividing into the right and left common iliac arteries. In this course the
aorta forms a continuous undivided trunk, which gradually diminishes in
size from its commencement to its termination, and gives off larger or
smaller branches at various points. Different parts of the vessel have
received particular names, derived from their position or direction : the
following are generally recognised, viz., the arch of the aorta, the thoracic
aorta, and the abdominal aorta. The short curved part, which reaches
from the ventricle of the heart to the side of the third dorsal vertebra, is
named the arch ; the straight part, which extends from that vertebra to the
diaphragm, is called the thoracic aorta ; and the remainder of the vessel,
down to its bifurcation, is designated the abdominal aorta.
Arch of the Aorta.
The arch of the aorta commences at the upper part or base of the left
ventricle of the heart, behind the pulmonary artery. At first it passes
upwards and to the right side, somewhat in the direction of the heart
THE AORTIC ARCH.
333
itself, and crosses obliquely behind the sternum, approaching at the same
time more nearly to that bone. Having gained the level of the upper
Fig. 249. VIEWOFTHE
AORTA FROM BEFORE,
WITH THE FIRST PART
OF ITS PRINCIPAL
BRANCHES DISSECTED
OUT OF THE BODY
(from R. Quain). \
1, commencement of
the aorta at the place
where it has been sepa-
rated from the left ven-
tricle, showing below the
semilunar valves closed,
in front and at the sides
the dilatations corre-
sponding to these valves,
or sinuses of Valsalva,
and above these the
origin of the right and
left coronary arteries ;
2, the ascending part of
the arch, with the dilata-
tion termed sinus of the
arch ; 3, the back of the
arch, or termination of
its descending portion ;
4, innominate artery ;
5, left carotid ; 6, left
subclavian ; 7, hollow
of the arch ; and, far-
ther down the aorta,
7, 7, indicate two out
of the series of inter-
costal arteries : the ceso-
phageal arteries are also
seen rising from the
front of the thoracic
aorta; 8, 8, right and
left renal arteries ; 9,
9, right and left com-
mon iliac arteries ; 10,
middle sacral artery ;
H, marks one of the
inferior diaphragmatic
arteries ; + , the coeliac
axis ; 12, the gastric
artery ; 13, the hepatic;
14, the splenic; 15,
superior mesenteric ;
16, inferior mesenteric ;
17, 17, right and left
spermatic arteries.
Fig. 250. VIEW OF THE
AORTA FROM BEHIND,
WITH ITS PRINCIPAL
BRANCHES (from R.
Quain).
The numbers have the same signification as in Fig. 249. The origin of the right and
left intercostal arteries close to each other and near the middle of the aorta posteriorly is
shown.
334
THE AOETIC ARCH.
border of the second costal cartilage of the right side, the vessel alters its
course, and is directed upwards, backwards, and to the left side, then
directly backwards, in contact with the trachea, to the left side of the body
Fig. 251. VIEW OP THE
THORACIC AND UPPER
PART OP THE ABDOMINAL
AORTA, SHOWING THEIR
RELATIONS AND PRINCIPAL
BRANCHES J TOGETHER
WITH A SKETCH OP THE
FIRST PARTS OP THE CA-
ROTID AND SUBCLAVIAN
ARTERIES.
The first ribs have been
divided in front of the
attachment of the scalenus
anticus muscles, and are
supposed to be drawn some-
what apart ; the rest of the
ribs down to the eleventh
are divided, along with the
intercostal muscles, at some
distance outside their angles ;
the internal intercostal mus-
cles are left in all the spaces
excepting the seventh and
eighth, in which they are
removed so as to expose the
extei-nal layer. The dia-
phragm has been cut trans-
versely near its crura, and
the part left behind is sup-
posed to be stretched up-
wards and to the sides.
a, the front of the hyoid
bone ; b, placed on the
anterior scalene muscles,
points to the upper part of
the pneumogastric nerves ;
c, the trachea below the
isthmus of the thyroid
gland, and lower down the
same letter is on the left bron -
chus ; c', one of the divisions
of the right bronchus emerg-
ing from behind the aorta ;
in the hollow of the aortic
arch, above 5, are seen the
cord of the ductus arteriosus
cut short, and the left re-
current nerve passing below
the arch ; + , is placed on the
right side between the re-
current nerve and the ver-
tebral artery as they pass
upwards ; d, the oesophagus ;
e, upon the right crus of the
diaphragm, and farther
down e', mark the recepta-
culum chyli of the thoracic
duct, and its commencement
by the lumbar plexus of lymphatic vessels and efferent mesenteric lacteal vessels; /, on
the third, seventh, and eleventh ribs, points to the vena azygos and superior intercostal
FORM OF THE AORTIC ARCH. 335
veins of the right side ; g, kidney, g f suprarenal body ; h, body of the fourth lumbar
vertebra.
/, sinus of the aortic arch, or ascending part of the arch : below this the semilunar
valves are seen closed and distended by injection ; /', posterior part of the arch, upon
which the left pneumogastric nerve is seen descending ; 1", descending thoracic part of
the aorta ; II, abdominal aorta emerging from between the crura of the diaphragm and
descending to near its termination.
Branches of the arch and thoracic aorta ; 1, right and left coronary arteries ; 2, inno-
minate ; 3, left carotid ; 4, left subclavian ; 5, bronchial arteries ; 6, 6, cesophageal
arteries : the lower figure points by a line to the thoracic duct ; 7, intercostal arteries,
marked in the sixth and seventh intercostal spaces.
Branches of the abdominal aorta ; 8, inferior diaphragmatic arteries cut short ; 9,
cceliac axis with the gastric, splenic, and hepatic arteries cut short ; 10, placed on the
aorta below the superior mesenteric artery (cut short) and the origin of the renal arteries ;
a little below this the origin of the spermatic arteries ; below //, the inferior mesenteric
artery, 11, 11, two of the lumbar arteries.
Branches of the carotid arteries ; the greater part of the right carotid artery has been
removed to show the ascent of the vertebral artery in the canal of the transverse pro-
cesses ; + is placed between the vertebral artery and the recurrent laryngeal nerve ; 3',
internal carotid artery ; 4, commencement of the external carotid artery ; close to this
the superior thyroid artery is given off, which is seen descending to the larynx and
thyroid body ; 5, the lingual and facial arteries ; 6, continuation of the external
carotid, &c.
Branches of the subclavian arteries ; on the right side the middle part of the scalenus
anticus muscle is removed ; on the left the figure 4 is placed close to the origin of the
four following vessels ; 5, vertebral ; 6, internal mammary ; 7, thyroid axis ; 7', its
suprascapular branch ; 7", its transverse cervical branch ; 8, superior intercostal artery,
supplying two spaces on the right side and one on the left, rising in common with the
deep cervical which turns upwards behind the subclavian artery ; 9, a posterior scapular
artery rising from the third part of the subclavian.
of the second dorsal vertebra. Arrived at that point, it bends downwards,
iu dining, at the same time, a little towards the middle line ; and at the
lower border of the body of the third dorsal vertebra, on its left side, the
arch terminates in the descending portion of the vessel. At its origin, the
arch of the aorta is larger than elsewhere, and presents externally three
small bulgings of nearly equal size, corresponding with the dilatations
which form the sinuses of Valsalva or of the aortic valves, already described
with the heart. Two of these sinuses are placed anteriorly and one
posteriorly, and in the two anterior sinuses are seen the orifices of the two
coronary arteries of the heart, the first branches given off by the aorta.
From the difference in the direction and connections of different portions
of the arch it is described as consisting of an ascending, a transverse, and a
descending portion.
The ascending portion of the arch of the aorta is placed at its commence-
ment behind the sternum, on a level with the lower border of the third
costal cartilage of the left side ; and it rises as high as the upper border of
the second costal cartilage of the right side. Its length is about two inches
or two inches and a quarter ; and its direction is curved.
In most cases there exists along the right side a dilatation, named the
great sinus of the aorta. This dilatation varies in size in different bodies,
and occasionally is not to be detected.
This portion of the aortic arch is enclosed in the pericardium, and,
together with the pulmonary artery, is invested by a fold of the serous
layer of that bag, in such a manner that both vessels are covered by the
serous membrane, except where they are in contact with each other.
At its commencement the ascending part of the arch is concealed by the
pulmonary artery, and by the right auricular appendage which overlaps it ;
but, further up, the aorta passes to the right side and the pulmonary artery
336 THE AORTIC ARCH.
to the left, and thus the aorta comes into view. It approaches very near to
the sternum, from which it is separated only by the pericardium, by some
connective tissue, and by the remains of the thymus gland lodged in the
mediastinal space : higher up, the descending vena cava lies on the right
side, and the pulmonary artery passes backwards on the left ; while behind
are placed the right branches of the pulmonary vessels.
The second or transverse part of the arch is covered on the left side by
the left pleura and lung, and is placed immediately in front and to the
left of the trachea, before its bifurcation into the bronchi : it touches like-
wise the oesophagus posteriorly. The upper border of the transverse part
of the arch has in contact with it the left innominate vein ; and from
it are given off the large arteries (innominate, left carotid, and left sub-
clavian), which are furnished to the head and the upper limbs. The lower
or concave border overhangs the bifurcation of the pulmonary artery, and
is connected with the left branch of that artery by the remains of the
ductus arteriosus. At or near its end this part of the arch is crossed in
front by the left vagus and phrenic nerves, with some offsets of the sympa-
thetic ; and the recurrent laryngeal branch of the vagus turns upwards
beneath and behind it.
The descending portion of the arch rests against the left side of the body
of the third dorsal vertebra, and is covered by the left pleura. To the
right side of this part of the arch is the oesophagus with the thoracic duct.
BRANCHES. The branches given off from the arch of the aorta are five in
number. Two of these, named the coronary or cardiac arteries, com-
paratively small, arise from two of the sinuses of Valsalva, and are distri-
buted to the walls of the heart. The other three are large primitive trunks,
which supply the head and neck, the upper limbs, and, in part, the thorax,
and usually arise from the middle or highest part of the arch, in the follow-
ing order : first, the innominate or brachio-cephalic artery, which soon sub-
divides into the right subclavian and the right carotid arteries ; second, the
left carotid ; and, third, the left subclavian artery. The origin of the left
carotid artery is usually somewhat nearer to the innominate artery than it is
to the subclavian artery of its own side.
PECULIAKITIES. (For more extended information on the peculiarities of the aorta
and of the blood-vessels in general, the student is referred to " The Anatomy of the
Arteries/' by Richard Quain, London, 1844.)
I. Peculiarities of the Arch itself.
Variations in height The arch sometimes reaches very nearly as high as the top
of the sternum. Occasionally it has been found an inch and a half below that level,
and in rare instances as much as three inches below it.
Double arch. This very rare variety has been known to occur in two forms. In
both of these the trachea and oesophagus passed through the circle formed by the two
divisions of the arch, which united behind them. In one form the arch retained its
inclination to the left side ; the pulmonary artery, placed in its proper position, was
united to the left division of the aorta by the obliterated ductus arteriosus ; and
from each division of the arch two branches arose, the carotid and subclavian. In
the other form a symmetrical ring was completed by the two divisions, each giving
rise to three vessels subclavian, and external and internal carotid ; while the pul-
monary artery dipped into the circle from above, and sent out its branches beneath it.
Right arch. Arching of the aorta to the right side has been observed to occur in
three different forms. 1st. Accompanying total transposition of the heart and
viscera. 2nd. Occurring without transposition of other parts, and with the left in-
nominate artery, right carotid, and right subclavian given off in succession. 3rd.
Occurring, in like manner, without transposition of other parts, its first branch being
PECULIARITIES OF THE AORTIC ARCH. 337
the left common carotid, the second the right common carotid, the third the right
subclavian, and the fourth the left subclavian, passing behind the oesophagus to
reach its destination.
II. Peculiarities affecting the Primary Branches.
Tti.e situation of the brandies. Instead of springing from the highest part of the
arch, the branches are frequently moved altogether to the right, and take origin from
the commencement of the transverse portion, or even from the end of the ascending
portion of the arch. In the ordinary arrangement the origin of the left carotid is
nearer to the innominate than to the left subclavian ; but the branches sometimes
arise at equal distances from each other, or are unusually widely apart. A very
frequent change consists in the approximation of the left carotid towards the in-
nominate artery.
TJie number and arrangement of the branches. These are extremely various. The
most frequent change met with is their reduction to two, from the left carotid being
united in a common trunk with the innominate artery. In cases of rare occurrence,
the carotid and subclavian arteries of the left side, as well as those of the right,
are conjoined in an innominate artery.
On the other hand, the number of the primary branches has been found to be
augmented to four, by the separation, as it were, of the innominate artery into the
right carotid and subclavian arteries, both arising directly from the aorta. In those
cases, the right subclavian artery is most frequently the last branch given off, pro-
ceeding from the back part of the arch, and passing behind the oesophagus to reach
its destination ; but sometimes it is given off in its proper order, as the first branch,
and in rare instances, it has been the second or third branch given off, in which
case it has passed behind those which preceded it, to reach the limb.
In those instances in which the right subclavian is the last vessel given off, and in
some other abnormal arrangements, a small pouch-like dilatation is sometimes found
on the arch, which is a vestige of the right aortic root, and is accounted for by the
changes in development which have led to the unusual disposition of the branches.
A remarkable variety is on record, in which the aorta divided at once into two
vessels, as is the usual arrangement in some quadrupeds, all the arteries for the head,
neck, and upper limbs, taking origin by a single trunk. In those cases the single
trunk referred to passed vertically upwards and divided into three branches, in the
form of a cross.
An abnormal arrangement of three branches springing from a normally arranged
arch has been observed, in which the two carotids have arisen by a common trunk,
and the two subclavians separately the right subclavian, in most instances, being
transferred beyond the other branches to the left end of the arch.
III. Peculiarities in which one or more Secondary Branches, usually given from
the Subclavian, are derived directly from the Aorta.
In nearly all instances belonging to this section, there is only one secondary branch
taking origin from the aorta ; and the occurrence may either accompany the ordinary
arrangement of the primary branches, or co-exist with a diminution or with an
increase in their number. The additional branch, when it is a normal artery trans-
posed, is almost invariably the left vertebral, which in nearly all those cases arises
between the left carotid and left subclavian arteries ; but it has also been observed
to proceed from the aorta beyond the last-named trunk. Very rarely the additional
branch is the right vertebral.
The thyroidea ima, a small supernumerary artery occasionally found ascending to
the thyroid body, sometimes arises from the arch of the aorta.
Development of variations in the aortic arch and its branches. Many of the most
frequent variations in the arrangement of the arch of the aorta and its branches may
be explained on referring to the development 'of those vessels, by supposing that one
of the usual branches has become obstructed in early foetal life, and that the circula-
tion has been carried on by the persistence of one of the original vessels which
otherwise would have been obliterated.
Thus in the case of double aortic arch, both the fourth branchial vascular arches
338
THE AORTIC ARCH BRANCHES.
remain pervious : in a case of right aortic arch, the fourth arch of the right side,
instead of that of the left, has remained pervious and has taken on permanent deve-
lopment, while at the same time adjusting deviations from the usual process of
development have occurred in parts of the other arches, which lead to a left in-
nominate being the first great vessel rising from the arch, and to the right carotid
and right subclavian arteries rising later in succession. Thus, too, transference of
the right subclavian artery from its usual connection with the innominate of a natural
left aortic arch to the fourth place of origin, and its remarkable passage behind the
trachea and gullet, may probably proceed from the obstruction of the part of the
fourth right arch which unites the aortic bulb with the aortic root, and is accompanied
by persistence of the aortic root itself extending from the main aorta below upwards
Fig. 252.
Fig. 252. DIAGRAMS TO ILLUSTRATE THE
RELATION OF SOME ABNORMAL DISPOSI-
TIONS OF THE AORTIC ARCH AND ITS
BRANCHES TO THE NORMAL CONDITION.
(I). The normal disposition as illus-
trated by Fig. 245, p. 326 ; (II), an
abnormal right aortic arch ; (III), a left
aortic arch with the right subclavian artery
displaced to the right aortic root ; (IV),
an abnormal right aortic arch with the
left subclavian displaced to the left aortic
root. Upper A, ascending part of the
aortic arch ; lower A, descending thoracic
aorta ; P, pulmonary trunk ; d, ductus
arteriosus ; a, right aortic root or its re-
mains ; a', left aortic root ; c, common
carotid arteries ; i, innominate artery ;
s, right, and s', left subclavian arte-
ries ; v, right, and v' t left vertebral
arteries.
to the subclavian artery. The similar
transference of a left subclavian artery,
in combination with the anomaly of
a right aortic arch, may be due to similar
abnormal states of development occur-
ring on a different side. So, also, many
of the other less marked variations in
the number and position of the perma-
nent branches proceeding from the aortic arch probably owe their origin to cognate
departures from the usual process of change in those parts of the original vascular
arches with which their roots are connected.
By reference to development we are likewise enabled to understand how the right
aortic arch of the bird, and the double aortic arch of reptiles, arise by obliteration
or permanence of different members of a series of branchial arches comparable with
those of fishes.
(Full reference to the history of cases of aortic varieties is given by Turner, " On
Varieties of the Arch of the Aorta," Brit. & For. Med. Cher. Review, 1863 ; and an
account of the origin of the varieties as explained by the observation of the develop-
ment of the vessels is given in the same paper, and in that of A. Thomson,
" Description of a Case of Right Aortic Arch," &c., Glasgow Med. Journ. 1862.)
BRANCHES OF THE ARCH OF THE AORTA.
THE CORONARY ARTERIES.
The coronary or cardiac arteries are two small vessels, named right and
left, which arise from the root of the aorta in the upper parts of the two
TEE CORONARY ARTERIES.
339
anterior of the three sinuses of Valsalva, on a level with the margins of
the semilunar valves.
The right coronary artery, about the size of a crow's quill, runs obliquely
towards the right side of the heart, lodged in the groove which separates
the auricle from the ventricle. It continues its course in the same groove,
along the posterior aspect of the organ, until it reaches the line of separation
between the two ventricles, where it divides into two branches. The smaller
Fig. 253.
Fig. 253. VIEW OF THE HEART AND
CORONARY ARTERIES FROM BEFORE (from
R. Quain).
The pulmonary artery has been cut short
close to its origin in order to show the first
part of the aorta. 1, anterior part of the
right ventricle ; 2, left ventricle ; 3, root of
the pulmonary artery ; 4, ascending part of
the arch of the aorta ; 4', the posterior or
descending part of the arch ; between these
is seen the transverse or middle part from
which the brachio-cephalic arteries take their
origin ; 4", the descending thoracic aorta ;
5, the appendix and anterior part of the
right auricle ; 6, those of the left auricle ;
7, the right, and 7', the left innominate or
brachio-cephalic veins joining to form the
vena cava superior ; 8, the inferior vena
cava below the diaphragm ; 9, one of the
large hepatic veins ; +, placed in the right,
auriculo-ventricular groove, points to the
right or posterior coronary artery ; + + ,
placed in the anterior interventricular
groove, points to the left or anterior coronary
artery.
of these continues transversely in the
groove between the left auricle and
ventricle, approaching the termina-
tion of the transverse branch of the
left coronary artery ; while the other
branch runs longitudinally downwards
along the posterior wall of the septum between the ventricles, giving
branches to each ventricle and to the septum between them.
In its course the right coronary artery gives, besides the offsets already
noticed, small branches to the right auricle and ventricle, and also to the
first part of the pulmonary artery. Along the right border of the ventricle
a rather large branch usually descends towards the apex of the heart, and
gives offsets, in its progress, to the anterior and posterior surfaces of the
ventricle.
The left coronary artery is rather smaller than the preceding, and arises
from the left anterior sinus of Valsalva. It passes behind and then to the
left side of the pulmonary artery, appearing between that vessel and the
left auricular appendage. At first it descends obliquely towards the anterior
interventricular sulcus, where it divides into two branches. Of these, one
pursues a transverse direction, turning outwards and to the left side in the
groove between the left ventricle and auricle, and approaching at the
posterior aspect of the heart the transverse branch of the right coronary
artery ; the other branch, much the larger, descends on the anterior
340 THE INNOMINATE ARTERY.
surface of the heart along the line of the interventricular groove, to
the right of the apex.
The left coronary artery supplies some small branches at its commence-
ment to the pulmonary artery, to the coats of the aorta, and to the left
auricular appendage ; its two branches also furnish throughout their course
smaller offsets, which supply the left auricle, both ventricles, and the
inter ventricular septum.
It has been customary to describe the transverse branches of the coronary arteries
as anastomosing in the left auriculo-ventricular sulcus, and the descending branches
as anastomosing near the apex of the heart ; and this description was never doubted
till it was found by Hyrtl, as the result of separate injection of these vessels, that
the branches of one coronary artery cannot be injected with material introduced into
the other. (Nat. Hist. Review, 1861, p. 321.)
PECULIARITIES. The coronary arteries have been observed in a few instances to
commence by a common trunk, from which they diverged and proceeded to their
usual destination. The existence of three coronary arteries is not a very rare occur-
rence, the third being small, and arising close by one of the others. Meckel, in one
instance, observed four, the supplementary vessels appearing like branches of one
of the coronary arteries transferred to the aorta.
THE INNOMINATE ARTERY.
The innominate, or brachio-cephalic, artery, the largest of the vessels
which proceed from the arch of the aorta, arises from the commencement of
the transverse portion of the arch, before the left carotid artery. From this
point the vessel ascends obliquely towards the right, until it arrives opposite
the sterno-clavicular articulation of that side, nearly on a level with the
upper margin of the clavicle, where it divides into the right subclavian and
the right carotid arteries. The place of bifurcation would, in most cases, be
reached by a probe passed backwards through the cellular interval between
the sternal and clavicular portions of the sterno-mastoid muscle. The
length of the innominate artery is very variable, but usually ranges from an
inch and a-half to two inches.
This artery, lying for the most part within the thorax, is placed behind
the first bone of the sternum, from which it is separated by the sterno-
hyoid and sterno-thyroid muscles, and a little lower down by the left
innominate vein, which crosses the artery at its root. The lower part of
the innominate artery lies in front of the trachea, which it crosses obliquely :
on - its left side is the left carotid artery, with the thymus gland or its
remains ; and to the right is the corresponding innominate vein and the
pleura.
No branches usually arise from this vessel.
PECULIARITIES. The length of the innominate artery sometimes exceeds two
inches, and occasionally it measures only one inch or less. Its place of division is a
point of surgical interest, inasmuch as upon it in a great measure depends the acces-
sibility of the innominate in the neck, and the length of the right subclavian artery.
It has sometimes been found dividing at a considerable distance above the clavicle,
and sometimes, but less frequently, below it. Though usually destitute of branches,
this vessel has been observed to supply a thyroid branch, the thyroidea ima, and
sometimes a thymic branch, or a bronchial, which descends in front of the trachea.
The thyroidea ima is an occasional artery. When present, it usually arises (as
already stated) from the innominate trunk, but in rare instances it has been observed
to come from the right common carotid artery, or from the aorta itself. It is of very
different size in different bodies, and compensates in various degrees for deficiencies
COMMON CAROTID ARTERIES. 341
or absence of the other thyroid arteries. It ascends to its destination in front of the
trachea, and its presence might therefore complicate the operation of tracheotomy.
COMMON CAROTID ARTERIES.
The common or primitive carotid arteries of the right and left sides of
the body are nearly similar in their course and position whilst they are in
the neck ; but they differ materially in their place of origin, and conse-
quently in their length and position, at their commencement. On the
right side the carotid artery commences at the root of the neck behind
the upper part of the sterno-clavicular articulation, at the bifurcation of the
innominate artery ; but on the left side the carotid arises within the thorax,
from the highest part of the arch of the aorta, very near the origin of the
innominate artery. The left carotid is therefore longer than the right, and
is at first placed at some depth within the thorax.
In consequence of this difference, it is convenient to describe, at first,
the thoracic portion of the left carotid, or that part which intervenes
between the arch of the aorta and the sterno-clavicular articulation ; after
which, the same description will suffice for both vessels.
Within the thorax, the left carotid ascends obliquely behind and at
some distance from the upper piece of the sternum and the muscles
(sterno-hyoid and sterno-thyroid) connected with that part of the bone ; it
is covered in front by the remains of the thymus gland, and is crossed by
the left innominate vein. This part of the artery lies in front of the
trachea, and of the oesophagus, which, at the root of the neck, deviates a
little to the left side ; the thoracic duct is also behind it. The left carotid
artery here lies between the innominate and the left subclavian arteries, and
the vagus nerve is to its outer side.
In the neck the common carotid artery of each side reaches from behind
the sterno-clavicular articulation to the level of the upper border of the
thyroid cartilage, where it divides into two great branches, of which one is
distributed to the cranium and face, and the other to the brain and eye.
These divisions have, from their destination, been named respectively the
external and internal carotid arteries.
The oblique course taken by the common carotid artery along the side of
the neck is indicated by a line drawn from the sterno-clavicular articulation
to a point midway between the angle of the jaw and the mastoid process of
the temporal bone. At the root of the neck, the arteries of opposite sides
are separated from each other only by a narrow interval, corresponding
with the width of the trachea ; but, as they ascend, they are separated by
a much larger interval, corresponding with the breadth of the pharynx and
larynx. The carotid arteries have the appearance of being placed farther
back at the upper than at the lower part of the neck, owing to the forward
projection of the larynx above.
The common carotid artery is enclosed, together with the internal jugular
vein and the vagus nerve, in a common membranous investment, continuous
with the deep cervical fascia. Separated by means of this sheath from all
the surrounding parts, except the vein and nerve just mentioned, the
carotid artery is deeply placed at the lower part of the neck, but is com-
paratively superficial towards its upper end. It is covered below by the
sterno-mastoid, sterno-hyoid, and sterno-thyroid muscles, in addition to the
platysma and the layers of fascia between and beneath the muscles ; and it
is crossed opposite or near the lower margin of the cricoid cartilage by
342
COMMON CAROTID ARTERIES.
the omo-hyoid muscle. From this point upwards to its bifurcation, the
vessel is covered by the sterno-mastoid, by the platysma and fascia, and
by the common integument ; and lies in a triangular space bounded by the
sterno-mastoid, the omo-hyoid, and the digastric muscles.
Fig. 254. VIEW OP THE RIGHT COMMON CAROTID AND SUBCLAVIAN ARTERIES, WITH
THE ORIGIN OP THEIR BRANCHES AND THEIR RELATIONS (from R. Quain). ^
The sterno-mastoid, sterno-thyroid, sterno-hyoid, and omo-hyoid muscles have been
removed, the trapezius has been detached from the outer part of the clavicle and turned
backwards, and the inner pai't of the clavicle has been removed : a, parotid gland near
the place where the duct of Stenson leaves it ; b, angle of the jaw and masseter muscle ; c,
submaxillary gland, enclosed between the digastric and stylo-hyoid muscles ; rf, divided
upper part of the sterno-mastoid muscle ; e, front of the hyoid bone ; /, thyroid cartilage ;
g, isthmus of the thyroid gland ; h, the trachea above the inter-clavicular notch of the
sternum ; i, i' } the sawn ends of the clavicle, the portion between them having been
removed ; k, the first rib, below which is seen the divided edge of the great pectoral
muscle, and beside it the subclavius ; /, front of the sternum ; TO, scalenus medius ; w,
levator anguli scapulas ; o, deep surface of the trapezius, which is turned aside; p, on the
RELATIONS OF THE COMMON CAROTIDS. 343
longus colli muscle, pointing to the pneuraogastric nerve ; IV, the uppermost of the nerves
of the axillary plexus ; A, the innominate artery ; 1, right common carotid artery ;
1', placed on the left sterno-thyroid muscle, points to a part of the left common carotid ;
2, internal carotid ; 2', upper part of the internal jugular vein, which has been removed
between i, and 2'; 3, and 4, external carotid ; 3, is placed at the origin of the superior
thyroid artery ; 4, at that of the lingual ; farther up the vessel may be seen the separa-
tion of the sterno-mastoid twig and the facial and occipital branches from the main vessel ;
5, is placed on the thyro-hyoid muscle between the hyoid and laryngeal branches of
the superior thyroid artery ; 5', the thyroid or glandular ; 6, the facial artery passing
over the base of the jaw ; 7, the superficial temporal artery ; 8, the first part, 8', the
third part of the arch of the subclavian artery ; 8", the subclavian vein separated from
the artery by the scalenus anticus muscle, shown by the removal of a portion of the
clavicle ; 9, is placed on the scalenus anticus muscle in the angle between the trans-
versalis colli and suprascapular branches of the thyroid axis ; 10, outer part of the supra-
scapular artery ; 10', transverse cervical branches passing into the deep surface of the
trapezius ; 10", the posterior scapular artery, represented as rising directly from the
third part of the subclavian artery, and passing through the axillary plexus of nerves
and under the levator auguli scapulae ; 11, on the scalenus anticus muscle, points to the
inferior thyroid artery near the place where the ascending muscular artery of the neck is
piven off; the phrenic nerve lies on the muscle to the outside ; at i, the suprasterual
twig of the suprascapular artery is shown.
Posteriorly, the artery is supported by the cervical vertebrae, the longus
colli and rectus capitis anticus muscles intervening. Hence the flow of
blood through it may be commanded by pressure directed backwards against
the vertebral column. The inferior thyroid artery crosses behind the
carotid sheath.
On the inner side the vessel is in juxtaposition with the trachea below,
and with the thyroid body (which often overlaps the artery), the larynx,
and the pharynx higher up. Along its outer side are placed the internal
jugular vein and the vagus nerve.
Relation to Veins. The internal jugular vein is close to the artery at the
upper part of the neck, but, in approaching the thorax, the veins of both
sides incline to the right, and hence that of the right side is separated from
the artery by an angular interval, while that of the left side approaches the
artery, and even lies in front of it at the lower part of the neck.
Crossing over the upper part of the common carotid artery to join with
the jugular vein, are two or more superior thyroid veins, which occasionally
form a sort of plexus over the artery. A middle thyroid vein not unfrequently
crosses the artery about half way up the neck.
The anterior jugular vein, where it turns outwards under the sterno-
mastoid muscle to join the subclavian, crosses the lower part of the artery.
This vein is generally of small size, but occasionally is rather large, and is
placed nearly over the carotid artery along the neck.
Relation to Nerves. The descending branch of the hypoglossal nerve,
descendens noni, usually rests, together with the branches of cervical nerves
which join it, on the fore part of the sheath of the carotid artery, and
crosses it from the outer to the inner side : in some instances this branch
descends within the sheath between the carotid artery and jugular vein.
The vagus nerve lies within the sheath of the vessels between the artery and
vein posteriorly : it was in one case observed to descend over the artery.
The sympathetic nerve is placed along the back of the sheath, between it and
the vertebral muscles, and the recurrent laryngeal nerve crosses inwards
behind the upper part of the sheath.
The common carotid artery usually gives off no branch, and therefore
continues of equal size in its whole length, except at its bifurcation, where
a slight enlargement is observable.
344
COMMON CAROTID ARTERIES.
Fig. 255.
Fig. 255. DISSECTION OF THE RIGHT SIDE OP THE NECK TO SHOW THE MUSCULAR
TRIANGLES, THE CAROTID AND SUBCLAVIAN ARTERIES, &o. (from R. Quaiu).
a, angle of the jaw and masseter muscle ; 6, parotid gland ; + , the posterior belly of
the digastric muscle ; c, submaxillary gland ; d, upon the mylohyoid muscle below the
anterior belly of the digastric muscle, and above the front of the hyoid bone ; e, upper
belly of the omohyoid muscle; e', lower belly; /, sterno-hyoid muscle; g, sterno-
thyroid ; 1, upon the sterno-mastoid muscle, points by a line to tbe upper part of the
common carotid artery ; 2, upon the scalenus anticus muscle, points to the third part of
subclavian artery ; 3, upon the scalenus medius, points to the superficial transverse cervical
artery crossing the axillary nerves ; 4, points to the posterior scapular artery, passing
under the levator scapulse muscle ; 5, placed upon the clavicle, points to the supra-
scapular artery ; 6, external carotid artery; 6', internal carotid artery ; 7, upon the thyro-
hyoid muscle, points to the superior thyroid artery giving superiorly its hyoid branch;
8, is placed upon the byo-glossus muscle within the arch of the lingual artery ; 9, placed
on the stylo-hyoid muscle, indicates the facial artery ; 10, origin of the occipital artery,
from the root of which the small sterno-mastoid artery is given off; between the occipital
and the facial arteries, +, upon the posterior belly of the digastric muscle, points to tbe
continuation of the external carotid artery before entering the parotid gland.
The absence of branches from the trunk of the common carotid is connected with
EXTERNAL CAROTID ARTERY. 345
the original absence of the neck in the foetus, and the comparatively late period at
which, when the neck is formed, the carotid artery becomes elongated with it.
PECULIARITIES. Origin. The right carotid artery occasionally arises directly from
the aorta, or in conjunction with the left carotid. When it arises from the aorta, it is
usually the first vessel from the arch, the subclavian being displaced ; but it has been
found to occupy the second place, the right subclavian, or, very rarely, the left carotid
being the first.
The place at which the right carotid artery commences, varies with the point of
bifurcation of the innominate artery. A change from the usual position on a level
with the upper border of the clavicle was found by R. Quain in the proportion of
about one case in eight and a half of those observed by him ; and it was found to
occur more frequently above than below that point.
The left carotid artery varies in its origin much more frequently than the right.
In the greater number of its deviations from the ordinary place of origin, this artery
arises from, or in conjunction with the innominate artery ; and in those cases in
which the right subclavian is a separate branch of the aorta, the two carotids most
frequently arise by a common trunk.
In cases of transposition, or of right aortic arch without other abnormality, the
left common carotid springs from a left innominate artery, which is the first vessel
to rise from the arch, and the right carotid is the second vessel.
Piace of division. This often deviates somewhat from its usual position ; it does
so more frequently in an upward than in a downward direction. It is often as high
as the os hyoides, and occasionally much higher. It is found from time to time oppo-
site the middle of the larynx, and, in rare instances, opposite the lower margin of the
cricoid cartilage, or even lower.
One case was observed by Morgagni, in which the carotid artery, measuring one
inch and a half in length, divided at the root of the neck. (" De Sedibus et Causis
Morbonim," &c. Epist. 29, Art. 20.)
The common carotid artery has been found, as a very rare occurrence, to ascend in
the neck without dividing into its two usual terminal branches ; the internal carotid
artery being altogether wanting.
In two recorded cases the common carotid artery was absent ; the external and
internal carotids arising directly from the arch of the aorta.
Occasional branches. The common carotid artery sometimes gives origin at its
upper part to the superior thyroid artery, and, in some rare cases, to a laryngeal or an
inferior thyroid branch ; also, in a few instances, to the vertebral artery.
EXTERNAL CAROTID ARTERY.
The external carotid artery, distributed mainly to the face and to the
walla of the cranium, is smaller than the internal carotid in young per-
sons ; but the two are nearly of equal size in adults. It reaches from
the point of division of the common carotid, opposite the upper margin of
the thyroid cartilage, to the neck of the condyle of the lower jaw-bone, or a
little lower, and there divides into its two terminal branches, the temporal
and the internal maxillary. It diminishes rapidly as it ascends, owing to
the number and size of the branches which spring from it.
At first the external carotid lies nearer to the middle line of the body
than the internal carotid ; but it soon becomes superficial to that artery, at
the same time curving slightly forwards as it ascends to its place of division.
At its origin this artery is concealed by the steruo-mastoid muscle, emerging
from beneath which, it is covered only by the platysma myoides and the
fascia, and traverses the upper part of a triangular intermuscular space
bounded by the sterno-mastoid, omo-hyoid, and digastric muscles ; it then
becomes deeply placed, passing beneath the stylo-hyoid and digastric
muscles, and finally becoming embedded in the substance of the parotid
gland. In the lower part of its course it is in contact with the pharynx
346 EXTERNAL CAROTID ARTERY.
and hyoid bone ; further up it is separated by a portion of the parotid gland
from the back of the ranms of the lower jaw, and rests upon the styloid pro-
cess and the stylo-pharyngeus muscle, which, with the glosso-pharyngeal
nerve, are interposed between it and the internal carotid artery.
Relation to Veins. This artery has usually no companion vein, though
it may be crossed superficially by small branches of the contiguous veins ;
but, when the internal maxillary vein joins the deep instead of the superficial
jugular, it accompanies the external carotid.
Relation to Nerves. Close to the digastric muscle the external carotid
artery is crossed by the hypoylossal nerve, and at a short distance from its
upper end, in the substance of the parotid gland, by the facial nerve. The
glosso-pharyngeal nerve lies between it and the internal carotid ; and the
superior laryngeal nerve is under both vessels.
BKANCHES. The branches of the external carotid artery are 'eight in
number, viz. three directed forwards, the superior thyroid, the lingual, and
the facial ; two directed backwards, the occipital and posterior auricular ;
and three extending upwards, the ascending pharyngeal branch, together with
the temporal and internal maxillary, the two terminal branches into which
the artery divides.
In addition to the principal branches here enumerated, the external
carotid gives off small offsets to the parotid gland.
PECULIARITIES. The peculiarities in the origin of this vessel have been noticed
along with those of the common carotid artery.
The branches are not unfrequently crowded together on the main stem, near tho
commencement, or at a higher point. Occasionally they take origin at regular
distances in the whole length of the vessel.
The usual number of branches may be diminished by the association with another
artery of one of the ordinary branches, or by the union into a single trunk of two or
three branches which are usually derived separately from the main artery : so also the
number may be augmented by the transfer to this vessel of some branch not ordinarily
derived from it, or by the addition of some unusual branch.
There is frequently present a small distinct branch for the sterno-mastoid muscle,
which bends outwards over the hypoglossal nerve.
BRANCHES OF THE EXTERNAL CAROTID ARTERY.
I. SUPERIOR THYROID ARTERY.
The superior thyroid artery, the first of the anterior set of branches, is
given off close to the commencement of the external carotid, immediately
below the great cornu of the hyoid bone. From this point the artery curves
forwards and downwards to the upper margin of the thyroid cartilage ; it
then descends a short distance beneath the omo-hyoid, sterno-hyoid, and
sterno-thyroid muscles, furnishing offsets to those muscles ; and, reaching the
anterior surface of the thyroid body, distributes branches to its substance,
and communicates freely with the branches of the inferior thyroid artery.
BRANCHES.
Besides the branches furnished to the muscles which cover it, and to the thyroid
body, together with some to the lowest constrictor of the pharynx, the superior
thyroid furnishes the following offsets, which have received distinctive names :
(a) The hyoid, a small branch, running transversely inwards immediately below
SUPERIOR THYROID ARTERY.
Fig. 256. '
317
Fig. 256. SUPERFICIAL VIEW OP THE ARTERIES OP THE HEAD AND NECK (from
Tiedemaun). J
a, placed upon the orbicularis oris near the place where it is joined by the levator labii
superiors, the zygomatici minor and major, and triangularis oris ; 6, upper part of the
steruo-inastoid muscle ; c, parotid gland near its duct ; d, body of the hyoid bone near
the place of meeting of the digastric, stylo-hyoid, sterno-hyoid, and omo-hyoid muscles ; e,
is placed on the clavicle at the place where, superiorly, the omo-hyoid dips behind it and
the trapezius muscle, and iuferiorly the interval exists between the pectoral and deltoid
muscles ; 1, trunk of the common carotid artery near its division into the external and
internal carotid arteries; 1', the internal carotid; 2, placed on the upper belly of the
omo-hyoid muscle, points to the superior thyroid artery ; 3, lingual artery and its hyoid
branch ; 4, placed on the submaxillary gland at the place where the facial artery is
sunk in the gland, and again where the artery turns over the lower jaw ; 4', termination
of the facial artery by division into the angular and lateral nasal branches ; 5, sub-
mental branch ; 6, inferior labial branches ; 7, transverse facial branch of the superficial
temporal ; 8, superficial temporal, passing over the zygoma and distributed by 8', 8', its
anterior and posterior divisions on the surface of the cranium ; 9, occipital artery rising
upon the cranium ; 9', its distribution and anastomosis with the temporal and posterior
auricular arteries ; 10, outer part of the snbclaviau artery ; 11, superficial cervical, and
12, posterior scapular arteries; 13, suprascapular artery ; 14, acromio-thoracic branches
of the axillary artery.
A A 2
348 EXTERNAL CAROTID ARTERY.
the os hyoides, and assisting to supply the soft parts connected with that bone.
This little artery sometimes unites, across the middle line, with its fellow from the
opposite side.
(b) A superficial descending branch, which passes downwards a short distance over
the sheath of the large cervical vessels, and ramifies in the sterno-mastoid and the
muscles attached to the thyroid cartilage, as well as in the platysma and neighbour-
ing integuments. The position of this branch with respect to the sheath of the
carotid artery is the only circumstance which gives it interest.
(c) The laryngeal branch, or superior laryngeal artery, proceeding inwards in
company with the superior laryngeal nerve, and piercing the thyro-hyoid membrane.
Before entering the larynx this branch is covered by the thyro-hyoid muscle. On
reaching the interior of the larynx, it ramifies in the small muscles, the glands, and
the mucous membrane of that organ.
(d) The crico-ihyroid, a small branch, to be noticed on account of its position
rather than its size. It crosses the membrane connecting the thyroid and cricoid
cartilages, and communicates with a similar branch from the other side : hence it
may be a source of hsemorrhage in the operation of laryngotomy.
PECULIARITIES. Size. The superior thyroid artery is frequently much larger, and,
on the other hand, it may be smaller than usual. In either case, the deviation from
the accustomed size is accompanied by an opposite alteration in other thyroid arteries.
It has been seen extremely small, ending in branches to the sterno-mastoid muscle
and the larynx. (See the observations on the inferior thyroid artery.)
Origin. The superior thyroid is often transferred to the upper part of the common
carotid artery ; and it has been seen conjoined with the lingual branch, or with that
and the facial branch of the external carotid.
There are sometimes two superior thyroid arteries.
Branches. The hyoid branch is frequently very small, or absent. The laryngeal
branch arises not unfrequently from the external carotid artery, and likewise, but rarely,
from the common carotid. Examples have occurred of this branch being of very
large size, and terminating in the thyroid body. The laryngeal artery occasionally
enters the larynx through a foramen in the thyroid cartilage ; and it has likewise
been observed to pass inwards below the cartilage.
II. LINGUAL ARTERY.
The lingual artery arises from the inner side of the external carotid,
between the origins of the superior thyroid and facial arteries. Curving
upwards and inwards, it reaches the upper margin of the hyoid bone,
behind the tip of its great cornu ; it then passes forwards under cover
of the hyo-glossus muscle, resting at first on the middle constrictor of
the pharynx, and afterwards on the genio-hyo-glossus muscle, in contact
with which it ascends almost perpendicularly to reach the under surface
of the tongue, and there makes its final turn forwards to the tip of that
organ, receiving the name of ranine artery.
At the posterior border of the hyo-glossus muscle, the hypoglossal nerve
crosses the artery, and passes forwards on a lower level, superficial to tlie
muscle.
BRANCHES. The branches of the lingual artery are as follows :
(a) The hyoid branch, running along the upper border of the hyoid bone/ and
supplying the contiguous muscles and skin.
(6) The dorsal artery of the tongue, which is often replaced by several smaller
branches. It arises from the deep portion of the lingual artery beneath the hyo-
glossus muscle, and ascends to supply the upper part, or dorsum, and the substance
of the tongue, ramifying as far back as the epiglottis.
(c) The sublinguat branch. Taking origin at the anterior margin of the hyo-
glossus, this branch turns slightly outwards, under cover of the mylo-hyoid muscle,
and between this and the sublingual gland. It supplies the substance of the gland,
and gives branches to the mylo-hyoid and other muscles connected with the maxillary
FACIAL ARTERY. 349
bone. Small branches are also distributed to the mucous membrane of the mouth,
and the inside of the gums.
(d) The ranine artery, which may be considered from its size and direction the
continuation of the lingual artery. It runs forwards beneath the tongue, giving
numerous branches as it proceeds, covered by the mucous membrane, and resting on
the genio-hyo-glossus muscle. Having reached the tip of the tongue, it has been
said to anastomose with the corresponding artery of the other side ; but this is denied
by Hyrtl. In the last part of its course it lies quite superficially at the side of the
frsenum.
PECULIARITIES. The origin of the lingual artery sometimes takes place from a
trunk common to it and the fiicial artery. It is occasionally joined with the superior
thyroid.
Branches. The liyoid branch is often deficient; and it appears that this branch
varies in size inversely with the hyoid branch of the superior thyroid.
The sublingual branch varies in size. It is sometimes derived from the facial
artery, and then perforates the mylo-hyoid muscle.
The lingual artery has been seen to give off as unusual branches, the submental
and ascending palatine.
III. FACIAL ARTERY.
The facial artery (art. maxillaris externa), taking origin a little above
the lingual artery, is first directed obliquely forwards and upwards beneatli
the base of the maxillary bone ; then changing its direction, it passes
upwards over the base of the lower maxilla, in front of the masseter muscle.
Commencing here its course upon the face, it is directed forwards near to
the angle of the mouth, and ascends to the inner canthus of the eye, where
it ends by anastomosing with the ophthalmic artery. In its whole course
the artery is tortuous, a circumstance connected with the great mobility of
the parts on which it rests.
In the neck, the facial artery, immediately after its origin, which is com-
paratively superficial, being covered only by the platysma and fascia, is
crossed by the digastric and stylo-hyoid muscles, and is then concealed
in the substance of the submaxillary gland. Emerging from the gland, it
turns over the border of the jaw, covered by the platysma : here the pulsation
of the artery is easily felt, and the circulation through it may be readily
controlled by pressure against the bone. In its progress over the face, it
is covered successively by the platysma and the zygomatic muscles, and
rests upon the buccinator, the levator anguli oris, and the levator labii
superioris.
The facial vein is separated by a considerable interval from the artery
on the face. It takes nearly a straight course upwards, instead of in-
clining forwards near the angle of the mouth, and it is not so tortuous as
the artery.
Branches of the portio dura nerve cross the vessel ; and the infraorbital
nerve is beneath it, separated by the fibres of the elevator of the upper lip.
BRANCHES. A. Cervical branches. The following branches are derived
from the facial artery below the lower jaw :
(a) The inferior or ascending palatine artery, a branch which ascends between the
stylo-glossus and stylo-pharyngeus muscles, and reaches the pharynx close to the
border of the internal pterygoid muscle. After having given small branches to the
tonsil, the styloid muscles, and the Eustachian tube, this artery divides near the
levator palati muscle into two branches, one of which follows the course of the cir-
cumflexus palati muscle, and is distributed to the soft palate and its glands, while the
other penetrates to the tonsil, and ramifies upon it with the branch to be next
described. The place of this artery upon the palate is often taken by the ascending
pharyngeal.
350 EXTERNAL CAROTID ARTERY.
(6) The tonsillar branch, which ascends along the side of the pharynx, and pene-
trating the superior constrictor of the pharynx, terminates in small vessels upon the
tonsil and the side of the tongue near its root.
(c) The glandular branches, a numerous series which enter the substance of the
submaxillary gland, whilst the facial artery is in contact with it ; and some of which
are prolonged upon the side of the tongue.
(d) The submental branch, the largest arising from the facial in the neck. Leaving
the artery near the point at which it turns upwards to the face, it runs forwards
below the base of the maxillary bone on the surface of the mylo-hyoid muscle and
subjacent to the digastric. Giving branches in its course to the submaxillary gland
and the muscles attached to the jaw, it approaches the symphysis of the chin and
divides into two branches ; one of these, running more superficially than the other,
passes between the depressor muscle of the lower lip and the skin, supplying both ;
while the other dips between that muscle and the bone, and ramifies in the substance
of the lip, communicating with the inferior labial branch.
B. Facial branches. Of the branches derived from the facial artery upon
the side of the face, some are directed outwards to the muscles, as to the
masseter and buccinator, and require only to be indicated. Larger branches
described with some detail are directed inwards, and are as follows :
(a) The inferior labial branch. This arises soon after the facial artery has turned
over the lower border of the maxilla, and running forwards beneath the depressor
anguli oris, distributes branches to the skin and the muscles of the lower lip, anasto-
mosing with the inferior coronary and submental branches, and with the inferior
dental branch of the internal maxillary artery.
(l>) The coronary artery of the lower lip. Arising near the angle of the mouth,
as often in conjunction with the superior coronary as from the facial separately, this
branch penetrates the muscular fibres surrounding the orifice of the moutb, takes a
transverse and tortuous course between those fibres and the mucous membrane of the
lip, and inosculates with the corresponding artery of the opposite side. Small twigs
from it ascend to supply the orbicular and depressor muscles, the glands, and other
structures of the lower lip; whilst others descend towards the chin, and communicate
there with other branches.
(c) The coronary artery of the upper lip. Larger and more tortuous than the
preceding branch, with which it often arises, this vessel runs across between the
muscles and mucous membrane of the upper lip, and inosculates with its fellow of
the opposite side. In addition to supplying the whole thickness of the upper lip, it
gives two or three small branches to the nose. One of these, named the artery of Ihe
septum, runs along the lower border of the septum nasi, on Avhich it ramifies as far as
the point of the nose ; another reaches the ala of the nose.
(d) The lateral nasal artery. This branch turns inwards to the side of the nose
beneath the common elevator of the nose and lip, and sends branches to the ala and
the dorsum of the nose. It anastomoses with the nasal branch of the ophthalmic, with
the artery of the septum nasi, and with the infiaorbital artery.
(e) Angular artery. Under this name is recognised the terminal part of the
facial artery, which inosculates at the inner side of the orbit wil/h a terminal branch
of the ophthalmic artery.
Communication between the superficial and deep branches of the external carotid
is established by the anastomoses of the facial artery with the infraorbital, buccal,
inferior dental, and nasal branches of the internal maxillary ; and between the
external and the internal carotids by the anastomosis of the facial with the ophthalmic
arteries.
PECULIARITIES. Origin. The facial artery not unfrequently arises by a common
trunk with the lingual. Occasionally it arises above its usual position, and then
descends beneath the angle of the jaw to assume its ordinary course.
Size. This artery varies much in size, and the extent to which it is distributed.
It has been observed, very rarely however, to end as the submental, not reaching the
side of the face ; in some cases it supplies the face only as high as the lower lip.
The deficiency of the facial artery is most frequently compensated for by an enlarge-
OCCIPITAL ARTERY. 351
ment of the nasal branches of the ophthalmic at the inner side of the orbit ; occa-
sionally by branches from the transverse facial or internal maxillary arteries.
Branches. The ascending palatine artery is in some instances transferred to the
external carotid. This branch varies in size and the extent to which it reaches. Not
unfrequently it is expended without furnishing any branch to the soft palate. When
it is thus reduced in size, the pharyngeal artery takes its place on the soft palate.
The tonsillar branch is not unfrequently altogether wanting.
The submental branch has been observed to take its rise from the lingual artery.
On the other hand, the facial artery, instead of the lingual, has been found to furnish
the branch which supplies the sublingual gland.
IV. OCCIPITAL ARTERY.
The occipital artery, arising from the posterior part of the external carotid,
usually opposite the facial or a little higher up, is directed upwards and
backwards, beneath the posterior belly of the digastric muscle, to the
interval between the transverse process of the atlas and the mastoid process
of the temporal bone. From that point it turns horizontally backwards
along the skull in the occipital groove of the temporal bone, internal to the
mastoid process and the sterno-mastoid, splenius, digastric, and trachelo-
mastoid muscles, and resting on the superior oblique and complexus muscles.
Lastly, changing its direction a second time, and piercing the cranial attach-
ment of the trapezius, it ascends beneath the integument on the back of the
head accompanied by the great occipital nerve, and divides into numerous
branches upon the upper and back part of the cranium. While in the neck,
the occipital artery crosses over the internal carotid artery, the vagus and
spinal accessory nerves, and the internal jugular vein ; and the hypoglossal
nerve turns from behind over it at its origin.
BRANCHES. The following branches are given from the occipital artery :
(a) Small muscular offsets to the digastric and stylo-hyoid muscles, and one of
larger size to the sterno-mastoid. This last is so regular a branch that it is known as
the sterno-mastoid branch.
(b) An auricular branch to the back part of the concha of the ear, and two or three
other muscular branches to the splenius and trachelo-mastoid.
(c) The meninneal branch. This runs up with the internal jugular vein, enters the
skull through the foramen jugulare, and ramifies in the dura mater of the posterior
fossa of the base of the skull.
(d) The cervical branch (rainus cervicalis princeps}. To the upper and back part of
the neck the occipital artery furnishes a branch thus designated. Descending a
short way, this vessel divides into a superficial and a deep branch. The former
ramifies beneath the splenius, sending offsets through that muscle to the trapezius ;
while the deep branch passes beneath the complexus, and anastomoses with branches
of the vertebral artery, and with the deep cervical artery. The size of this branch
varies very much.
(e) The superficial or cranial branches. These pursue a tortuous course between
the integument and the occipito-frontalis muscle ; and in proceeding upwards on the
skull they separate into diverging branches, which communicate with the branches
of the opposite artery, as well as with those of the posterior auricular artery, and of
the temporal artery at the vertex and side of the skull.
A small twig, the mastoid branch, enters the skull through the mastoid foramen,
and ramifies in the dura mater.
PECULIARITIES. Origin. The occipital artery is occasionally derived from the
internal carotid, and from the ascending cervical branch of the inferior thyroid an
offset of the subclavian artery.
Course. The occipital artery sometimes passes outside the trachelo-mastoid muscle,
instead of internally to it. The chief portion of the vessel was found, in one instance, to
pass over the sterno-mastoid muscle, only a small artery being placed in the usual
EXTERNAL CAROTID ARTERY.
Fig. 257.
Fig. 257. DEEP VIEW OP THE CAROTID, SUBCLA.VIAN, AND AXILLARY ARTERIES (from
Tiedemann).
The great pectoral, the sterno-mastoid, and the sterno-hyoid and sterno-thyroid muscles
have been removed ; the front part of the deltoid has been divided near the clavicle ; the
greater part of the digastric muscle has been removed, and the upper part of the splenius
capitis and trachelo-mastoid divided near the mastoid process. Subclavian Artery arid-
its Branches. 1, first or inner part of the subclavian artery, giving rise to the thyroid
axis and internal mammary, and also to x , the vertebral artery ; 2, third part of the
POSTERIOR AURICULAR. TEMPORAL. 253
subclavian artery outside the scalenus anticus muscle ; 3, first part of the axillary artery
giving rise to theacromial thoracic, short thoracic, &c. ; 4, third part of the axillary artery,
giving rise to the subscapular, circumflex, &c. ; 5, commencement of the brachial artery ;
6, superficial transverse cervical artery ; 6', placed on the scalenus anticus muscle marks
the superficial ascending cervical branch ; 7, posterior scapular artery, arising from the
subclavian artery behind the scalenus anticus muscle, and separate from the thyroid axis ;
8, acromial branches of the acromial thoracic ; 9, pectoral branches of the same; 10, long
thoracic artery outside the pectoralis minor muscle ; +, posterior circumflex branch
of the axillary artery (the anterior circumflex is seen rising from the opposite side of the
same part of the axillary trunk) ; 11, subscapular artery, passing between the subscapularis
and teres minor muscles to proceed to the lower angle and dorsum of the scapula ; 12,
thoracic descending branch of the subscapular artery. Carotid Artery and its Branches.
13, lower part, and 14, upper part of the right common carotid artery; 15, trunk of the
external carotid artery, brought fully into view by the removal of the digastric muscle ;
16, trunk of the internal carotid artery ; 17, 17, inside the thyroid axis of the subclavian
artery, and on the inferior thyroid artery where it is distributed in the gland ; 18, superior
thyroid artery, anastomosing in the gland with the inferior thyroid ; 1 9, lingual
artery, brought into view by the removal of the lower part of the hyo-glossus muscle ; 20,
facial artery, giving off the palatine, tonsillitic and submental ; 21, inferior labial ; 22,
coronary artery ; 23, occipital artery ; 24, posterior auricular artery ; 25, superficial
temporal artery ; 26, internal maxillary artery ; 27, transverse facial, given off in this
instance directly by the external carotid artery.
position. The artery has, in a few instances, been seen to turn backwards below the
transverse process of the atlas.
Branches. The posterior auricular and the pharyngeal arteries sometimes take
origin from the occipital.
V. POSTERIOR AURICULAR ARTERY.
The posterior auricular artery, a small vessel, arises from the external
carotid a little higher up than the occipital. It ascends, under cover of
the parotid gland, and resting on the styloid process of the temporal bone,
reaches the angle formed by the cartilage of the ear with the mastoid pro-
cess. It is crossed by the portio dura of the seventh nerve. Somewhat
above the mastoid portion of the temporal bone it divides into two sets of
branches, of which one set inclines forwards to anastomose with the posterior
branch of the temporal artery, and the other backwards towards the occiput,
on which it communicates with the occipital artery.
BRANCHES. The following are the branches given off by the posterior
auricular artery :
(a) Small branches to the parotid gland and the digastric muscle.
(b) The stylo-mastoid branch. This twig enters the foramen of the same name in
the temporal bone ; on reaching the tympanum, it divides into delicate vessels,
which pass, some to the mastoid cells, others to the labyrinth. One branch is con-
stantly found in young bodies to form, with the tympanic branch of the internal
maxillary artery which enters the fissure of Glaser, a vascular circle around the
auditory meatus, from which delicate offsets ramify upon the membrana tympani.
This small tympanic branch sometimes arises from the occipital artery.
(c) Auricular branches. As it passes the back of the ear, the auricular artery
gives one or two branches which supply the posterior surface of the concha, and turn
over the margin, or perforate the substance of the auricle to gain the anterior
surface.
PECULIARITIES. The posterior auricular artery is frequently very small, and has
been seen to end in the stylo-mastoid branch. It is often a branch of the occipital.
VI. TEMPORAL ARTERY.
The temporal artery, one of the two branches into which the external
carotid artery finally divides a little below the condyle of the lower jaw,
354 EXTERNAL CAHOTID ARTERY.
continues upwards in the direction of the parent vessel, whilst the other
branch (the internal maxillary) curves forwards under cover of the jaw.
The temporal aitery is at first imbedded in the substance of the parotid
gland, in the interval between the meatus of the ear and the condyle of the
lower jaw. Thence it ascends over the root of the zygoma, against which it
may readily be compressed. From this point onwards, it lies close beneath
the skin, supported by the temporal muscle and fascia ; and, about two
inches above the zygoma, divides into two branches, which again sub-
divide and ramify beneath the integument on the side and upper part of
the head.
BRANCHES. Besides several small offsets to the parotid g^nd, some
branches to the articulation of the lower jaw, and one or two to the masseter
muscle, i he temporal artery gives off the following branches :
() The transverse artery of the face. This branch arises whilst the temporal
artery is deeply seated in the parotid gland, through the substance of which it
runs nearly horizontally forwards; getting between the parotid duct and the zygoma,
it rests on the masseter muscle, and is accompanied by one or two transverse
branches of the facial nerve. It gives small vessels to the parotid gland, the masseter
muscle, and the neighbouring integument ; and divides into three or four branches,
which are distributed to the side of the face, anastomosing with the infraorbital and
facial arteries.
(6) The middle temporal branch. This arises close above the zygoma, and imme-
diately perforating the temporal fascia, sends branches to the temporal muscle,
which communicate with the deep temporal branches of the internal maxillary
artery. An offset from this artery runs to the outer angle of the orbit, where it
gives branches to the orbicularis palpebrarum muscle.
(c) The anterior auricular branches, two or more in number, superior and infe-
rior. These branches arise above the middle temporal. They are distributed to the
fore part of the pinna, the lobe of the ear, and a part of the external meatus, anasto-
mosing with the ramifications of the posterior auricular artery.
(d) The anterior temporal branch, one of the two terminal branches of the
temporal artery. This vessel inclines forwards as it ascends over the temporal fascia,
and ramifies extensively upon the forehead, supplying the orbicular and occipito-
frontal muscles, the pericranium, and the skin, and communicating with the supra-
orbital and frontal branches of the ophthalmic artery. On the upper part of the
cranium the branches of this artery are directed from before backwards. When it is
desired to take blood from the temporal artery, the anterior temporal branch is
selected for the operation.
(e) The posterior temporal branch. This is usually larger than the anterior,
passes back on the side of the head, above the ear, and over the temporal fascia :
its branches ramify freely in the coverings of the cranium, both upwards to the
vertex, where they communicate with the corresponding vessel of the opposite side,
and backwards to join with the occipital and posterior auricular arteries.
PECULIARITIES. The temporal artery is frequently tortuous, especially in aged
persons. Occasionally a large unusual branch runs forward above the zygoma to the
upper part of the orbit. The temporal artery sometimes joins with the ophthalmic
and furnishes large frontal arteries.
The anterior temporal branch is sometimes larger than the posterior, and passing
backwards over the vertex of the head, communicates with the occipital.
The transverse artery of the face varies in size; occasionally it is much larger than
usual, and takes the place of a defective facial artery. In some instances the trans-
verse artery arises directly from the external carotid.
VII. INTERNAL MAXILLARY ARTERY.
The internal maxillary or deep facial artery, the larger of the two
terminal branches of the external carotid, is concealed by the parotid gland
at its origin below the condyle of the jaw ; it curves horizontally forwards
INTERNAL MAXILLARY ARTERY. 355
between the jaw and the internal lateral ligament of the temporo-maxillary
joint, then passes obliquely forwards and upwards on the outer surface of
the external pterygoid muscle (not unfrequeutly beneath and within it),
aad opposite the interval between the two heads of that muscle, bends
inwards to the spheno- maxillary fossa, where it ends by division into a
number of branches.
To facilitate the arrangement of its numerous branches, this artery may
be considered in three parts, viz. : 1, the part between the jaw and internal
lateral ligament ; 2, the part in contact with the external pterygoid muscle ;
and, 3, the part in the spheno-maxillary fossa.
Fig. 258. -
Fig. 258. DEEP DISSECTION OP THE HEAD AND FACE, TO snow THE INTERNAL
MA.XILLARY ARTERY AND ITS BRANCHES (from Tiedemann). ^
The right half of the calvarium, the zygomatic arch, and the upper part of the lower
jaw have been removed : the external pterygoid muscle and some of the superficial muscles
of the face have been divided, and the internal pterygoid and buccinator muscles are
exposed : 1, facial artery, rising over the edge of the lower jaw ; 2, inferior labial
branches ; 2 , deep mental branch of the inferior maxillary artery ; 3, facial artery con-
tinued ; 4, superior coronary of the facial ; 5, lateral nasal branch ; 6, frontal branch of
the ophthalmic artery, giving descending twigs to communicate with the angular branch
of the facial and with the dorsal nasal ; 7, internal carotid artery ; 8, external carotid
artery at the place where it passes through the parotid gland, which has been removed ; 9,
division of the external carotid artery into superficial, temporal and internal maxillary
arteries ; 10, superfical temporal ; 11, masseteric branch of the external carotid artery ;
12, superiorly the trunk of the internal maxillary or deep facial artery, and inferiorly
its inferior maxillary branch ; 13, placed on the zygoma, points to the middle meningeal
branch, and above on the dura mater to its distribution ; 14, placed on the lower part of
the temporal muscle separated from the coronoid process of the jaw, indicates the
deep temporal branches of the artery; 15, pterygoid branches; 16, buccal artery; 17,
posterior superior dental, and deepest part of the internal maxillary artery where it enters
the spheno-maxillary fossa ; 18, branches of the infraorbital artery issuing upon the face.
356 EXTERNAL CAROTID ARTERY.
BRANCHES. A. Branches of the first part. The branches of the first
part of the artery all pass through osseous foramina.
(a) The tympanic branch, of small size and variable in origin, passes deeply behind
the articulation of the lower jaw, and enters the fissure of Glaser, supplying the
laxator tympani muscle, and the tympanic cavity, where it ramifies upon the
membrana tympani. It anastomoses in the tympanum with the stylo-mastoid and
Vidian arteries.
(b) The middle or great meningeal artery, by far the largest of the arteries which
supply the dura mater, passes directly upwards under cover of the external ptery-
goid muscle, and enters the skull by the spinous foramen of the sphenoid bone.
Within the cranium, it ascends to the anterior inferior angle of the parietal bone, and
divides into numerous branches, which ramify in deep arborescent grooves on the
inner surface of the bones, some passing upwards over the parietal bone as high as the
vertex, and others backwards even to the occipital bone.
Immediately on entering the cranium, the meningeal artery gives minute branches
to the ganglion of the fifth nerve and to the dura mater near the sella turcica, and a
small twig which enters the hiatus Fallopii, and anastomoses with the stylo-mastoid
branch of the posterior auricular artery. It also inosculates with branches of the
ophthalmic artery.
The middle meningeal artery is accompanied by two veins.
(c) The small meningeal artery, usually arising faom the preceding branch,
enters the skull through the foramen ovale, to supply the dura mater in the middle
fossa.
(d) The inferior dented artery, passing downwards, enters the dental canal along
with the inferior dental nerve, and subsequently escapes on the face by the mental
foramen. As it enters the canal, it gives off the mylo-hyoid branch, which, with the
nerve bearing the same name, runs in a groove on the inner surface of the jaw,
below the dental foramen, and ramifies on the under surface of the mylo-hyoid
muscle. In its course through the bone, the inferior dental artery gives off small
offsets, which ascend to enter the minute apertures in the extremities of the fangs of
the teeth, and supply the pulp of each ; and, before emerging at the mental foramen,
it sends forwards a branch which supplies the incisor teeth and inosculates with its
fellow of the opposite side. The terminal or facial branches anastomose with the
inferior coronary and submental arteries.
B. Brandies of the second part. The branches of this part are chiefly
distributed to muscles, and are named muscular.
(a) The deep temporal branches, two in number (anterior and posterior), ascending
between the temporal muscle and the cranium, supply that muscle, and anastomose
with the branches of the other temporal arteries, and with minute branches of the
lachrymal artery, through small foramina in the malar bone.
(b) The pterygoid branches, small short offsets, irregular in number and origin,
are distributed to the pterygoid muscles.
(c) The masseteric is a small but regular branch which passes from within out-
wards, above the sigmoid notch of the lower maxillary bone, to the deep surface of
1 he masseter muscle. It is often joined at its origin with the posterior temporal
branch.
(d) The buccal branch runs obliquely forwards upon the buccinator muscle with
the buccal nerve ; it is distributed to that and other muscles of the cheek, and anas-
tomoses with the branches of the facial artery.
C. Branches of the third part. These branches, like those of the first
series, enter bony foramina or canals.
(a) The alveolar or superior maxillary branch, arising near the tuberosity of the
maxillary bone, frequently in common with the infraorbital branch, runs tortuously
forwards upon the surface of the upper jaw, and gives off the superior dental and
other branches which enter the foramina of the tuberosity, and supply the pulps of
INTERNAL MAXILLARY. PHARYNGEAL. 357
the upper molar and bicuspid teeth, besides ramifying in the lining membrane of
the maxillary sinus. Other small branches supply the gums.
(6) The infraorbital artery runs horizontally forwards into the infraorbital canal,
and having traversed that canal along with the superior maxillary nerve, emerges
upon the face at the infraorbital foramen.
Whilst still in the canal, it sends upwards into the orbit small branches, which
enter the inferior rectus and the inferior oblique muscle of the eye and the lachrymal
gland, and others downwards to supply the front teeth. On the face it gives branches
upwards, to the lachrymal sac and inner angle of the orbit, anastomosing with the
nasal branches of the ophthalmic and facial arteries, and sends other branches down-
wards, beneath the levator labii superioris, which join the ramifications of the trans-
verse facial, buccal, and superior coronary arteries.
(c) The descending or superior palatine artery descends perpendicularly through
the posterior palatine canal, with the palatine nerve, and runs along the hard palate.
In front it ends in a small vessel which ascends through the incisor foramen, and
anastomoses with the artery of the septum. While descending in the canal, this
artery sends off twigs through the bone, which communicate on the soft palate with
the ascending palatine artery.
(d) The Yidian branch traverses the Vidian canal with the nerve of the same
name ; it is distributed to the Eustachian tube and the top of the pharynx, and sends
a small vessel into the tympanum.
(e) The pterygo-palatine, a very small branch, passes backwards through the
pterygo-palatine canal to reach the top of the pharynx, to which, and to the Eusta-
chian tube and sphenoidal cells, it is distributed.
(/) The nasal or spheno-palatine artery enters the spheno-palatine foramen, and
divides into two or three branches, some of which ramify extensively over the
spongy bones, while others supply the posterior ethmoidal cells and the antrum.
One long branch, the artery of the septum, runs forwards along the septum nasi, ends
in a small vessel which enters the incisor foramen, and inosculates with the descending
palatine artery.
PECULIARITIES. Origin. The internal maxillary artery is very constant in its place
of origin. It has, however, been seen to arise from the facial.
Course. The artery often passes under cover of the external pterygoid muscle,
crossing the inferior maxillary division of the fifth nerve. It has likewise been
observed to issue from under cover of the external pterygoid by piercing the middle
of that muscle. When the artery is placed beneath the muscle, it has been found
lodged in a notch in the posterior margin of the external pterygoid plate, and bound
down by fibrous structure.
Branches. The middle meningeal artery occasionally furnishes the lachrymal
artery (usually an offset of the ophthalmic), a peculiarity which may be looked on
as resulting from the enlargement of an ordinary anastomosing branch.
In a case in which the internal carotid artery was wanting, two tortuous branches
from the internal maxillary entered the skull by the foramen rotundum and foramen
ovale, to supply its place. (Quain " On the Arteries," pi. 13, fig. 8.)
VIII. ASCENDING PHARYNGEAL ARTERY.
The pharyngeal artery, long and slender, the smallest branch of the
external carotid which has received a distinctive designation, arises most
commonly from half an inch to an inch above the origin of the external
carotid ; and in its straight course upwards rests on the rectus capitis
anticus, close to the surface of the pharynx, between it and the internal
carotid artery, and is thus directed up towards the base of the skull.
BRAJSCHES. These are very small, and may be divided into three sets,
viz., those to the pharynx ; a set directed outwards ; and meningeal branches.
(a) The pharyngeal branches pass inwards, for the most part, to the pharynx. One
or two small and variable branches ramify in the middle and inferior constrictor
muscles. Higher up than these is a larger and more regular branch, which runs
358 EXTERNAL CAROTID ARTERY.
upon the upper constrictor, and sends small ramifications to the Eustachian tube,
and to the soft palate and tonsil.
The last mentioned, or palatine branch, is sometimes of considerable size, and
supplies the soft palate, taking the place of the inferior palatine branch of the facial
artery, which in such cases is small. It divides into an anterior and a posterior
twig, both of which anastomose with their fellows of the opposite side in the middle
line.
Fig. 259.
Fig. 259. DEEP VIEW OF THE LINGUAL AND PHARYNGEAL ARTERIES (from R. Quain). |
In the preparation from which this drawing has been taken half the lower jaw has been
removed, and the tongue has been drawn forwards between the teeth ; the external
pterygoid muscle has been removed, and the temporal muscle has been turned up from
within the zygoma ; a, the root of the zygoma, above the glenoid cavity ; 6, placed on the
lobe of the ear, points by a line to the styloid process, from which the stylo-glossus and
stylo-pharyngeus are seen passing downwards and forwards, and the stylo-hyoid detached
from the hyoid bone is thrown backwards with the digastric muscle ; c, transverse pro-
cess of the atlas ; d, upper surface of the tongue ; e t sawn surface of the symphysis of the
lower jaw ; /, the angle of the hyoid bone ; 1, left common carotid artery ; 2, internal
carotid artery ; 3, external carotid artery ; 3', placed on the stylo-pharyngeus muscle,
points by a line to the upper part of the external carotid artery divided where it enters
the parotid gland ; 4, superior thyroid artery, its laryngeal branch passing upon the thyro-
hyoid membrane ; 5, lingual artery about to pass within the hyo-glossus muscle ; 5', placed
on the genio-hyo-glossus, points to the continuation of the lingual artery in the ranine ;
6, the trunk of the facial artery cut short ; 6', its tonsillar and pharyngeal branches ;
7, occipital artery cut short ; 8, ascending pharyngeal artery ; 8', its upper part turning
down upon the pharynx ; 9, internal maxillary artery as it passes into the spheno-max-
illary fossa, and .gives the posterior dental and the infraorbital arteries ; 9', middle
meningeal artery; 10, placed on the deep surface of the temporal muscle, which is
turned up and shows some cut branches of the deep temporal arteries.
INTERNAL CAROTID ARTERY. 359
(b) The external branches, small and irregular, are distributed to the rectus anticu-
muscle, the first cervical ganglion of the sympathetic nerve, some of the cerebra-
nerves as they issue from the skull, and to lymphatic glands. Some of them anasto-
mose with the ascending cervical branch of the subclavian artery,
(c) The menintjeal branches are terminal twigs, which pass through the foramen
lacerum posticum to end in the dura mater.
PECULIARITIES. This artery varies greatly in its place of origin from the carotid.
It occasionally springs from another source, as from the occipital or internal carotid,
and, in a few instances, it has been seen double.
INTERNAL CAROTID ARTERY.
The internal carotid artery is distributed to the brain, to the eye
with its appendages, and in part to the forehead. It extends directly
upwards from the termination of the common carotid artery, opposite the
upper border of the thyroid cartilage, to the carotid foramen of the temporal
bone. Entering the cranial cavity through the carotid canal, it crosses the
foramen lacerum medium, and, turning upwards on the side of the sphenoid
bone, it passes forwards on the carotid groove of that bone. Thence it
turns abruptly upwards on the inner side of the anterior clinoid process,
and divides opposite the inner end of the Sylviaii fissure of the brain, into
the anterior and middle cerebral arteries.
In the neck, the internal carotid artery varies in length according to the
height of the division of the common carotid. It rests on the rectus anticus
major muscle, and has the pharynx and tonsil on its inner side. The
internal jugular vein is in contact with it as far as the base of the skull,
lying on its superficial and posterior aspect : and placed more deeply behind
it are the vagus nerve and main trunk of the sympathetic. At its com-
mencement the artery is covered only by the sterno-mastoid muscle, by the
plcitysina myoides, and by fascia, and lies to the outer side of the external
carotid. It soon, however, becomes concealed by the parotid gland, and.
lies internal and posterior to the external carotid trunk, and is crossed first
by the occipital artery, and by the hypoglossal nerve and the digastric and
stylo-hyoid muscles, three structures which lie superficial to both carotid
arteries : and higher up, by the styloid process, the stylo-pharyngeus
muscle and the glos?o-pharyngeal nerve, which, together with, in some
cases, the pharyngeal branch of the vagus nerve, pass forwards between the
external and internal carotid arteries.
Within the cranium, the internal carotid artery has a very tortuous
course, curving forwards and inwards within the carotid canal, then turning
upwards to reach the sphenoid bone, on which it is at first directed hori-
zontally forwards, and afterwards resumes the vertical position on the inner
side of the anterior clinoid process. In this part of its course the artery is
accompanied by the carotid and cavernous plexuses of the sympathetic
n-jrve. After leaving the carotid canal, it lies iu the floor of the cavernous
sinus, and in contact with it externally are the nerves which pass through the
sphenoidal fissure. Opposite the anterior clinoid process it pierces the layer
of dura mater which forms the roof of the sinns, and becomes invested with
arachnoid membrane.
By the winding course of the internal carotid artery in the skull, the brain is
probably in some degree protected from the force of the pulsations with which the
blood is propelled from the heart. Occasionally the artery presents considerable
tortuosity before entering the carotid canal, especially in apoplectic subjects, the
trunk having probably been elongated by the force of the pulsations.
360 INTERNAL CAROTID ARTERY.
The vertebral artery is similarly tortuous before entering the cranium.
BRANCHES. In the neck the internal carotid artery gives usually no
branch. While within the carotid canal it sends a small offset to the tym-
panum, which anastomoses with the tympanic and stylo-mastoid arteries.
Within the cavernous sinus some small branches proceed from it to supply
the walls of the sinus and the adjacent dura mater.
Opposite the anterior clinoid process, the internal carotid gives off the
ophthalmic artery ; and at the Sylvian fissure of the brain, before dividing
into the anterior and middle cerebral arteries, it gives off or is joined by the
posterior communicating artery, a slender anastomotic branch which lies
parallel to its fellow of the opposite side and unites the internal carotid
with the posterior cerebral artery.
PECULIARITIES. In very rare cases of abnormal arrangement of the arch of the
aorta, the internal carotid artery has arisen as a primary trunk. A few examples of
its entire absence are recorded.
The posterior communicating artery has been occasionally seen replaced by two
very small vessels.
BRANCHES OF THE INTERNAL CAROTID ARTERY.
1. OPHTHALMIC ARTERY.
The ophthalmic artery, arising from the internal carotid artery by the
side of the anterior clinoid process, enters the orbit by the foramen opticum,
below and to the outer side of the optic nerve. It soon changes its direction,
passing over the nerve to reach the inner wall of the orbit, along which it
runs forwards, and terminates in branches which ramify on the forehead
and side of the nose.
BRANCHES :
(a) The lachrymal artery, arising on the outer side of the optic nerve, passes
forwards along the upper border of the external rectus muscle to the lachrymal
gland, in which the greater number of its branches are distributed. Some of the
branches pass onwards to the eyelids and conjunctiva, joining with other palpebral
branches ; and one or two delicate malar branches pierce the malar bone and reach
the temporal fossa, where they join branches from the deep temporal arteries. The
lachrymal artery has also branches of communication through the sphenoidal fissure
with small offsets from the middle meningeal artery.
(6) The central artery of the retina, a very small vessel, pierces the sheath and
substance of the optic nerve about a quarter of an inch behind its junction with the
eyeball, and runs imbedded within it to the retina, in which it ramifies in minute
branches. A very delicate vessel, demonstrable in the feetus, passes forwards through
the vitreous humour, to reach the posterior surface of the capsule of the crystal-
line lens.
(c) The supraorbital branch ascends above the muscles, and coursing forwards to
the supraorbital notch, in company with the frontal nerve, terminates on the
forehead. It distributes branches to the eyelids, and communicates with the temporal
artery.
(d) The ciliary arteries are divisible into three sets, viz., short, long, and anterior
ciliary. The short ciliary arteries, varying from twelve to fifteen in number, enclose
the optic nerve as they pass forwards to reach the posterior aspect of the sclerotic
coat, which they pierce, and enter the eyeball about a line or two from the entrance
of the optic nerve. The long ciliary arteries, two in number, also enter the back of
the eyeball, and then pass forwards, one on each side, between the choroid mem-
brane and the sclerotic, as far as the ciliary ligament, where they divide into
branches. The anterior ciliary arteries are derived from some of the muscular
branches ; they form a vascular circle around the fore part of the eyeball, and then
OPHTHALMIC ARTERY.
Fig. 260. ,
361
Fig. 260. SEMIDIAGRAMMATIC VIEW OP THE ARTERIES OP THE ORBIT AND NEIGHBOUR-
ING PARTS, WITH THEIR BRANCHES AND ANASTOMOSES (founded on Hirschfeld and
Leveille, with additions).
The outer wall of the orbit has been removed, the sinus maxillaris is laid open, the
eyelids are turned forwards, and the external and superior recti, and the superior oblique
muscles have been partially removed, a, optic nerve ; b, hook, holding up the posterior
part of the superior rectus muscle, the anterior part of which is left attached to the eye-
ball ; c, lachrymal gland, thrown up on the frontal bone ; d, insertion of the inferior
oblique muscle ; e, inferior rectus ; /, /, anterior and posterior portions of the divided
external rectus ; g, maxillary sinus ; h, hook, holding up the eyelids, of which the deep
surface is exhibited.
I, internal carotid artery below the inferior aperture of the carotid canal of the temporal
bone, which is indicated higher up by a ring surrounding the artery ; I', the part of the
artery situated within the temporal bone, a second ring indicating the place of the upper
aperture of the temporal canal ; I", the part of the artery situated on the sphenoid bone ;
upon this artery, 1, twig to the mastoid cells and tympanum ; 2, twigs in the cavernous
sinus ; 3, communicating to the posterior cerebral ; 4, middle cerebral ; 5, anterior
cerebral.
II, basilar artery ; upon this artery, 6, posterior cerebral ; 7, superior cerebellar : the
accented numbers, 3', 4', 5', 6', 7', indicate, on the left side, the arteries already named
under the same numbers on the right side, and with these and the anterior communicating
branch marked by +, complete the Circle of Willis.
III, upper part of the external carotid artery dividing into III x , the superficial temporal,
and III', III", the internal maxillary artery ; upon the latter artery, 1, inferior dental
branch ; 2, middle meningeal ; 3, 3, masseteric and pterygoid branches; 4, buccal ; 5, 5,
anterior and posterior deep temporal ; 6, posterior superior dental ; 7, infraorbital ; 7',
branches of the same issuing upon the face ; 8, part of the internal maxillary, which
turns into the spheno-maxillary fossa.
IV, facial artery, terminating at 11, in the angular, and giving off, at 12, the lateral
nasal branches, and others which communicate with the infraorbital.
In the orbit the following numbers indicate the ophthalmic artery and its branches : 1,
the ophthalmic artery at its origin from the internal carotid ; 1', the same artery con-
tinued on the upper and inner side of the orbit ; 2, lachrymal branch ; 3, central artery of
the retina ; 4, some of the ciliary arteries ; 5, 5, upper and lower muscular branches ;
6, supraorbital ; 7, 7', posterior and anterior ethmoidal arteries ; 8, palpebral ; 8', 8",
its superior and inferior divisions ; 9, frontal; 10, nasal communicating with the angular
of the facial.
B B
362
INTERNAL CAROTID ARTERY.
pierce the sclerotic within a line or two of the margin of the cornea. All these
ciliary arteries anastomose together within the eyeball, their distribution in which
will be particularly described with the anatomy of the eyeball.
(e) The muscular branches, subject to much variety, usually arranged in an upper
and lower set, supply the muscles of the orbit.
(/) The ethmoidal branches are two in number, a posterior and an anterior. They
pass through the posterior and anterior internal orbital foramina, the latter in
company with the nasal branch of the ophthalmic nerve ; and both arteries, having
furnished branches to the ethmoidal cells, enter the skull, supply the adjacent dura
mater, and send branches through the cribriform lamella to the nose.
(a) The two palpebral branches, superior and inferior, arise near the front of the
orbit, usually together, but soon diverge, one lying above, the other below the
tendon of the orbicularis muscle at the inner angle of the eye ; they form arches,
one in each lid, and send branches to the caruncula lachrymalis and the lachrymal
sac.
(Ji) The nasal branch courses forwards above the tendon of the orbicularis muscle
to the root of the nose, where it ramifies, maintaining a free communication with the
nasal and the angular branches of the facial artery.
(i) The frontal branch runs close to the preceding, but on reaching the margin of
the orbit turns upwards on the forehead, where it anastomoses with the supraorbital
artery.
Fig. 261. Fig. 201. VIEW OP THE
DISTRIBUTION OF THE
BRANCHES OF THE IN-
TERNAL CAROTID AND
VERTEBRAL ARTERIES TO
THE LOWER PARTS OF
THE BRAIN (altered
from Hirschfeld and
Leveille). g
On the left side of the
brain a portion of the
middle lobe of the cere-
brum has been removed so
as to open up the fissure of
Sylvius and expose the
convolutions of the island
of Reil ; and the left half
of the cerebellum has been
removed to show the lower
surface of the posterior
cerebral lobe. 1, placed
on the optic commissure,
points to the divided stem
of the left internal carotid
artery where its cerebral
distribution begins ; 2,
anterior cerebral branch,
exposed fully by the re-
moval of a portion of the
left optic nerve ; 2', placed
on the knee or anterior
bend of the corpus callo-
sum between its two arteries ; x , placed on the lamina cinerea in front of the optic
commissure, marks the anterior communicating artery ; 3, middle cerebral artery,
passing into the fissure of Sylvius and distributing its branches over the convolutions of
the island of Reil and others beyond; 4, placed between the infundibulum and the
corpora albicantia, points by a line to the left posterior communicating artery ; 5, basilar
artery ; 6, posterior cerebral artery, its distribution exposed on the left side by the
removal of half the cerebellum ; 7, placed on the pons Varolii, points to the right
superior cerebellar artery ; 8, anterior inferior cerebellar artery ; between 7, and 8, one of
the largest of the transverse branches of the basilar artery ; 9, 9, right and left vertebral
arteries ; 10, posterior inferior cerebellar arteries ; 11, anterior spinal arteries.
CEREBRAL ARTERIES. 363
II. ANTERIOR AND MIDDLE CEREBRAL ARTERIES.
The terminal branches of the internal carotid artery supply the anterior
and greater part of the pia mater and brain.
The anterior cerebral, commencing at the subdivision of the internal
carotid at the inner end of the fissure of Sylvius, turns forwards towards
the middle line to reach the longitudinal fissure between the anterior lobes
of the cerebral hemispheres, and is connected with the vessel of the opposite
side by the anterior communicating artery t a branch not more than two
lines in length. The two anterior cerebral arteries, lying close together, in
the next place turn round the anterior border of the corpus callosum, run
backwards on its upper surface, concealed by the cerebral hemispheres, and
end by anastomosing with the posterior cerebral arteries. In their course
they give numerous branches to the brain.
The middle cerebral artery, larger than the anterior, inclines obliquely
outwards, taking the course of the fissure of Sylvius ; within this it divides
into several branches, which ramify in the pia mater investing the surfaces
of the anterior and middle lobes of the brain, and join with the branches of
both the anterior and posterior cerebral arteries. Numerous small branches,
without ramifying in the pia mater, turn upwards at once, and enter the
brain at the anterior perforated spot, through which they reach the corpus
striatum.
One or two choroid arteries, which sometimes arise directly from the
internal carotid, passing backwards, enter the fissure between the middle
lobe and the crus cerebri, to reach the descending cornu of the lateral
ventricle, in which they are distributed to the choroid plexus.
PECULIARITIES. In rare instances, the anterior cerebral arteries have united into a
single trunk, like the basilar artery behind, and have again divided into a right and
left artery. The anterior communicating artery is frequently double.
. CIRCLE OF WILLIS.
A remarkable anastomosis exists between the branches of the vertebral
and internal carotid arteries within the cranium, by which the circulation in
the brain may be equalised, and any irregularity which might arise from the
obliteration of one, or even two of the vessels, may speedily be remedied by
a corresponding enlargement of the others. This anastomosis, known as the
circle of Willis, results from a series of communications between the follow-
ing branches. The anterior cerebral arteries are connected together, as
already mentioned, in the longitudinal fissure by the anterior communicating
artery. The right and left internal carotids, the trunks from which the
anterior cerebral arteries arise, are united by the posterior communicating
arteries to the posterior cerebral arteries, which arise behind from a single
trunk the basilar artery. Within or opposite to the area of this vascular
circle are the following parts of the encephalon, viz., the commissure of
the optic nerves, lamina cinerea, infundibulum and tuber cinereum, corpora
albicantia, posterior perforated spot with part of the crura cerebri, and the
origin of the third pair of nerves.
Frequently the posterior cerebral artery of one side arises by an enlarged posterior
communicating artery from the internal carotid, and is connected only by a slender
vessel with the basilar.
B r, 2
SUBCLAVIAN ARTERIES.
SUBCIAVIAN ARTERIES.
The subclavian artery is only the commencing portion of a long trunk
which forms the main artery of the upper limb, and which is artificially
divided for purposes of description into three parts the subclavian,
axillary, and brachial arteries.
The subclavian artery, arising on the right side from the extremity of the
innominate stem, and on the left from the arch of the aorta, passes a short
way up into the neck, arches outwards over the pleura, and rests between
the scalenus anticus and scalenus medius muscles on the first rib. At the
outer border of the first rib it ceases to be called subclavian, and is con-
tinued into the axillary artery.
Each subclavian artery is conveniently divided into three parts, the
first part extending from the origin of the vessel to the inner border of the
anterior scalenus muscle ; the second consisting of the portion of the vessel
situated behind that muscle ; and the third reaching outwards to the external
border of the first rib. In examining each of these portions in detail, it
will be necessary in the first part to give separate descriptions for the right
and the left sides, as there is a material difference in the anatomy of the two
vessels.
THE FIRST PART OF THE RIGHT SVJBCLAVIAN ARTERY Commences close to
the trachea, at the division of the innominate artery, behind the upper part
of the sterno-clavicular articulation, and ends at the inner margin of the
anterior scalenus muscle. Separating from the carotid artery, it arches up-
wards and outwards, and ascends above the level of the clavicle to an extent
which varies in different cases. It is deeply placed, being covered by the
platysma, the stern o-mastoid, the sterno-hyoid, and sterno- thyroid muscles,
and the deep cervical fascia. It is in contact with the pleura iuferiorly, and
is separated by an interval from the longus colli muscle behind.
Relation to Veins. The subclavian vein lies lower than the first part of
the right subclavian artery, close under the clavicle. In its course to join
this vein, the internal jugular passes in front of the artery near the scalenus
muscle, as do also, near the middle line, the anterior jugular and a vertebral
vein.
Relation to Nerves. The vagus nerve passes in front of the artery on
the inner side of the internal jugular vein, and its recurrent laryngeal
branch, turning round below the artery, ascends behind. Some cardiac
branches of the sympathetic nerve pass down over the artery.
THE FIRST PART OF THE LEFT SUBCLAVIAN ARTERY arises from the upper
surface of the arch of the aorta, at the left end of its transverse portion,
and ascends to the margin of the first rib, behind the insertion of the anterior
scalenus muscle. It is, therefore, longer than the first part of the right sub-
clavian, and ascends at first almost vertically out of the chest, instead of
arching, like that vessel, outwards across the neck. It is at first overlapped
by the left lung, and is covered in front and on the left side by the pleura ;
it rests on the longus colli muscle, and lies, for a short space, in front of
the oesophagus (here deviating to the left side), and the thoracic duct. To
the inner or right side of the vessel are situated the left carotid and trachea,
and further up the oesophagus and the thoracic duct.
Relation to Veins. The internal jugular vein is immediately before the
artery, where it turns outwards from the thorax, close to the scalenus
muscle ; and the left innominate vein is likewise anterior to it.
RELATIONS OF THE SUBCLAVIAN ARTERIES.
365
Relation to Nerves. The pneumogastric nerve is anterior to the first part
of the left subclavian artery, and parallel with it, the recurrent branch on
tbis side turning round below the arch of the aorta. The phrenic nerve
Fig. 262.
Fig. 262. VIEW OP THE EIGHT COMMON CAROTID AND SUBCLAVIAN ARTERIES, WITH
THE ORIGIN OF THEIR BRANCHES AND THKIR RELATIONS (from 11. Quaill).
For the description of the upper part of this figure, see p. 342. The following expla-
nation relates to the subclavian artery and its branches : 8, the first part, 8', the third
part, of the arch of the subclavian artery ; 8", the subclavian vein, shown by the re-
moval of a portion of the clavicle ; 9, is placed on the scalenus anticus muscle in the
angle between the transverse cervical and suprascapular branches of the thyroid axis ;
30, outer part of the suprascapular artery; 10', transverse cervical branches passing
into the deep surface of the trapezius ; 10", the posterior scapular artery, represented as
rising directly from the tbird part of the subclavian artery, and passing through the
axillary pi ex us of nerves and under the levator anguli scapulae ; 11, on the scaleiius anticus
muscle, points to the inferior thyroid artery, near the place where the ascending muscular
artery of the neck is given off; the phrenic nerve lies on the muscle to the outside ; ?',
the suprasternal twig of the suprascapular artery.
366 SUBCLAVIAN ARTERIES.
descends over the artery along the inner margin of the scalenus muscle, im-
mediately outside the thyroid axis. The cardiac nerves of the left side,
descending from the neck, are close to the artery.
THE SECOND PAIIT OF THE SUBCLAVIAN ARTERY, the'short portion concealed
by the anterior scalenus muscle, forms the highest part of the arch described
by the vessel across the neck. Somewhat less deeply placed than the first
part, it is covered by the platysma and the stern o-mastoid muscle, with
layers of the cervical fascia. Behind, it rests against the middle scalenus
muscle ; and below, it lies on the pleura.
Relation to Veins and Nerves. The subclavian vein is lower than the
artery, and is separated from it by the anterior scalenus muscle. The
phrenic nerve, which descends obliquely inwards over that muscle, usually
crosses the first part of the subclavian artery of the left side close to the
muscle, while on the right side, not having quite reached the margin of the
muscle at the level of the artery, it is usually separated by the muscle from
the second part of the artery.
THE THIRD PART OF THE SUBCLAVIAN ARTERY lies in a small triangular
space, the sides of which are formed by the omo-hyoid muscle and clavicle,
and the base by the anterior scalenus muscle ; the omo-hyoid is in some
instances immediately over the artery. The subclaviau artery is nearer to
the surface here than elsewhere, being covered only by the platysma and
layers of the cervical fascia, but towards its termination it becomes deeper,
sinking under the clavicle and the subclavius muscle.
Relation to Veins. The subclavian vein continues to be anterior to, and
lower than the artery. The external jugular vein lies over the artery, and
receives on the outer side from the shoulder the two veins which accompany
the suprascapular and transverse cervical arteries. The veins in some cases
form a sort of plexus over the artery.
Relation to Nerves. Above the vessel are placed the large brachial
nerves, the lowest cord formed by the union of the last cervical and the first
dorsal nerve behind and in contact with it. The small nerve of the
subclamus muscle passes down over the artery, and the space which lodges
the artery is crossed in front by the superficial descending (clavicular)
branches from the cervical plexus of nerves.
BRANCHES. Four branches are usually described as arising from each
subclavian artery. Of these, three, namely, the vertebral, the internal
mammary, and the thyroid axis, generally spring close together from the
first part of the artery, near the inner side of the anterior scalenus muscle ;
while the fourth branch, the superior intercostal, is usually found internal to
that muscle on the left side, but arising under cover of it from the second
part of the artery on the right.
The vetebral artery springs from the upper and back part of the sub-
clavian, and ascends in the neck to reach the interior of the skull ; the
internal mammary proceeds from the lower side of the vessel, and descends
into the fore part of the chest and abdomen ; the thyroid axis arises from
the front of the artery, and divides into three branches, one of which, the
inferior thyroid, is distributed in the fore part of the neck, whilst the other
two, the suprascapular and the transverse cervical, pass outwards across the
neck to the shoulder ; lastly, the superior intercostal and deep cervical
arise by a common stem from the back part of the artery, and pass into the
upper part of the thoracic wall and the posterior muscles of the neck. The
deep cervical is reckoned by some writers as a fifth branch of the subclavian
artery, but it usually rises in common with the superior intercostal artery.
BRANCHES OF THE SUBCLAVIAN. VERTEBRAL. 367
Another branch, in the great majority of instances, arises from the third
part of the artery. This is most frequently the posterior scapular artery, a
branch which otherwise is derived from the transverse cervical, one of the
divisions of the thyroid axis. This circumstance is of surgical interest, as
the third part of the subclavian artery is the portion of the vessel usually
tied for axillary aneurism. As the right subclavian artery is likewise
accessible to the surgeon in its first part, it is proper to mention that the
distance between the origin of the vessel and its first branch is usually
between half an inch and an inch, and that it very rarely is less than half
an inch or more than an inch and a half.
PECULIARITIES. The variations in origin of the subclavian arteries have been con-
sidered along with the peculiarities of the arch of the aorta.
Course. The height to which these vessels reach in the neck is liable to some
variation. Most commonly the artery crosses the neck a little higher than the
clavicle, but it is sometimes placed as high as an inch or even an inch and a half
above the level of that bone. The greater extent of elevation above the clavicle, how-
ever, is especially seen in the artery of the right side. Occasionally the subclavian
artery perforates the anterior scalenus muscle, and in a few rare cases it has been seen
altogether in front of the muscle, and close to the subclavian vein. That vein has
been also seen to pass with the artery behind the scalenus muscle.
Branches. Besides the variation in amount of the branches already referred to,
it may be noticed that, in a few cases, one or more of the three first branches have
been found moved inwards from tlieir usual position, or outwards to another division
of the subclavian. Sometimes two, and much more rarely three branches arise from
the third part of the vessel.
BRANCHES OF THE SUBCLAVIAN ARTERY.
I. VERTEBRAL ARTERY.
The vertebral artery, which is usually the first and largest branch of the
subclavian, arising from the upper and back part of that vessel, passes
upwards and a little backwards, and enters the transverse foramen of the
sixth cervical vertebra not unfrequently that of some higher vertebra.
The vessel then ascends in a vertical direction through the series of foramina
of the transverse processes, as far as to the upper border of the axis ; there
it inclines outwards to reach the corresponding foramen of the atlas, and
after passing through that aperture winds backwards and inwards in the
groove on the neural arch of that vertebra, and, piercing the dura mater,
enters the skull through the foramen magnum. Finally, it proceeds
upwards and forwards, and turning round from the sile to the front of the
medulla oblongata on the ba^ilar process of the occipital bone, unites with
the vessel of the opposite side, at the lower border of the pons Varolii, to
form the basilar artery.
At its commencement, the vertebral artery lies behind the internal jugular
vein, and on approaching the vertebrse passes between the longus colli and
the scalenus anticus muscle. On the left side, the thoracic duct in ascending
crosses in front of the vessel from within outwards.
While within the foramina of the cervical vertebrae, the artery is accom-
panied by a plexus of the sympathetic nerves and by the vertebral vein,
which, as the vessels issue from the foramen of the sixth vertebra, is in
front of the artery : the cervical nerves as they emerge from the inter-
vertebral foramina lie behind it. The suboccipital nerve passes out beneath
368
SUBCLAVIAN ARTERIES.
it, where it lies on the groove of the atlas, and at that point the artery is
covered by the superior oblique muscle.
Within, the skull it turns round the side of the medulla oblongata, be-
tween the origin of the hypoglossal nerve and the anterior root of the
suboccipital, and then lies between the anterior surface of the medulla and
the basilar process of the occipital bone.
Fig. 263.
Fig 263. DEEP DIS-
SECTION OF THE SUB-
CLAVIAN ARTERY ON THE
RIGHT SIDE, SHOWING
THE ORIGIN AND COURSE
OP THE VERTEBRAL
ARTERY (from Tiede-
mann). ^
a, Upper pai-t of the
sterno-mastoid muscle, its
clavicular part divided
below ; 6, spinous process
of the axis ; c, superior
oblique muscle ; d, placed
on the inferior oblique
muscle, points by a line
to the posterior arch of the
atlas vertebra ; e, semi-
Bpinalis colli ; /, placed
on the longus colli, points
to the transverse process
of the sixth cervical ver-
tebra ; </, on the first rib,
points to the scalenus
anticus muscle cut near
its attachment ; 1, inno-
minate artery ; 2, right
common carotid ; 3, right
subclavian ; below it, the
origiu of the internal
mammary artery ; above
it, 4, the thyroid axis,
its branches cut short ;
5, vertebral artery, pass-
ing up through the canal
of the transverse pro-
cesses and giving branches
to the muscles ; 5', placed
on the rectus major, points
to its horizontal part on
the arch of the atlas ; 6, placed on the lower part of the divided scalenus medius, points
to the trunk of the deep ceivical and first intercostal arteries ; 6', placed on the sealenus
medius, points to the deep cervical artery ; 7, occipital arteiy emerging from below the
sterno-mastoid and other muscles attached to the mastoid process.
BRANCHES. A. Cervical branches :
(a) In the neck, the vertebral artery sends off at different points of its course
several small branches named spinal arteries. Each of these, entering the spinal
canal through an intervertebral foramen, divides into two branches; one of these
passes along the roots of the spinal nerves, supplying the spinal cord and its mem-
branes, and anastomoses with the other spinal arteries ; the other branch ramifies
on the back part of the bodies of the vertebrae,- in the same manner as similar branches
derived from the intercostal and lumbar arteries.
CEREBRO-SPINAL BRANCHES OF THE VERTEBRAL. 369
(a) Muscular branches of variable size are distributed to the deep-seated cervical
muscles.
B. Cranial branches :
(a) The posterior meningeal artery is a small branch which arises opposite the
foramen magnum, and ramifies between the dura mater and the bone in the occipital
fossa, and upon the falx cerebelli. There are sometimes two of these small vessels.
(b) The posterior spinal artery, arising at an obtuse angle from the vertebral,
inclines backwards round the medulla oblongata to reach the back part of the spinal
cord ; aided by reinforcements from small arteries which ascend upon the cervical
and dorsal nerves through the intervertebral foramina, it may be traced along the
cord, lying behind the roots of the nerves, as a minute tortuous vessel, or rather a
series of little inosculating vessels, as far as the second lumbar vertebra, where it
terminates in ramifications on the cauda equina.
(c) The anterior spinal artery, somewhat larger than the preceding, arises near
the end of the vertebral artery, and descends obliquely in front of the medulla
oblongata. Immediately below the foramen magnum, it unites with the correspond-
ing vessel of the opposite side, so as to form a single trunk, which descends a short
distance only along the middle line in front of the spinal cord, forming the upper
part or commencement of the anterior median artery of the cord. This anterior
spinal branch of the vertebral artery supplies therefore only the upper part of the
cord ; the remainder being provided with a series of small arteries, which are derived
in the neck from the vertebral and inferior thyroid arteries, in the back from the
intercostal, and below this from the lumbar, ilio-lumbar, and lateral sacral arteries.
These small vessels enter the spinal canal at irregular intervals through the inter-
vertebral foramina, and, passing along the roots of the nerves, communicate with
each other along the middle line by means of ascending and descending branches ;
so that, by a succession of anastomoses, a very slender single vessel, of varying thick-
ness, named the anterior median artery, appears to extend from the one end to the
other of the cord. This vessel, or chain of inosculating vessels, supplies the pia mater
and the substance of the cord some entering the anterior median fissure. At the
lower end of the spinal cord it sends branches downwards on the cauda equina.
On a part of the spinal cord near the lower end, and in front of the posterior roots
of the nerves, may be found another small artery, about equal in size to the anterior
spinal.
(d) The posterior inferior cerebellar artery, the largest of the branches, arises from
the vertebral near the pons, and sometimes from the basilar artery : it turns back-
wards and outwards, between the hypoglossal and pneumogastric nerves, over the
restiform body and near the side of the opening of the fourth ventricle, to reach the
under surface of the cerebellum. Here, running backwards between the inferior
vermiform process and the hemisphere, it divides into two branches : one of which
continues backwards in the sulcus between the hemispheres ; while the other, turning
outwards, ramifies on the under surface of the cerebellum as far as its outer border,
over which the ultimate divisions of each branch anastomose with those of the
superior cerebellar arteries. This artery partly supplies the hemisphere and the
vermiform process, and gives branches to the choroid plexus of the fourth ventricle.
PEGULIAKITIES. Origin. The right vertebral artery has been seen to arise from
the common carotid of the same side, in some of those cases in which the right sub-
clavian has been given as a separate vessel from the posterior part of the aorta. In
very rare instances, the right vertebral artery arises from the aorta.
The left vertebral artery is not unfrequently derived from the aorta, in which case
it generally arises between the left carotid and subclavian arteries, but sometimes it
is the last of the branches from the arch.
The left vertebral artery in a few instances, and the right vertebral in one, have been
found to arise by more than a single root ; and an example of three roots to a ver-
tebral artery has been placed on record. (R. Quain, plate 24, fig. 2.) Two roots may
proceed from the subclavian artery, or one from the subclavian and one from the
aorta.
Course. Instead of entering the foramen of the sixth vertebra, the vertebral artery
of one side not unfrequently enters higher up, through the foramen of the fifth, or
370 SUBCLAVIAN ARTERIES.
fourth, or more rarely of the third vertebra, or even, according to several anatomists,
of the second. On the other hand, the vertebral artery has been seen to enter the
foramen of the seventh vertebra.
Branches. In. the neck, the vertebral artery has been found, though very rarely,
to give branches which are usually derived from the subclavian, such as the superior
intercostal and the inferior thyroid.
BASILAR AND POSTERIOR CEREBRAL ARTERIES.
The basilar artery, the single trunk formed by the junction of the right
and left vertebral in the middle line, extends from the posterior to the
anterior border of the pons Varolii, along the median groove of which it lies
under cover of the arachnoid. The length of this artery is therefore about
equal to that of the pons, at the anterior border of which it divides into
two terminal branches, the posterior arteries of the cerebrum.
BRANCHES. Besides numerous small branches to the substance of the
pons, the basilar artery gives off the following :
(a) The transverse arteries, several on each side, pass directly outwards. One, the
artery of the acoustic nerve, accompanies that nerve into the internal auditory
meatus and labyrinth of the ear.
(6) The anterior inferior cerebellar arteries pass backwards, one on each side, to
the anterior part of the under surface of the cerebellum, anastomosing with the
inferior cerebellar branches of the vertebral arteries.
(c) The superior cerebellar arteries arise so close to the bifurcation of the basilar,
that this artery is described by several anatomists as dividing into four branches.
Each one turns backwards and outwards immediately behind the third nerve, and,
entering the groove between the pons Yarolii and the crus cerebri, turns round the
latter, close to the fourth nerve, to reach the upper surface of the cerebellum, where
it divides into branches. Of these some extend outwards, and one or more back-
wards along the superior vermiform process, to reach the circumference of the cere-
bellum, where they anastomose with the branches of the inferior cerebellar arteries ;
while others run inwards to supply the vermiform process and the valve of Vieussens,
and in part the velum interpositum.
The posterior cerebral artery on each side, resulting from trie division of
the basilar, passes outwards, parallel to the superior cerebellar artery, and
separated from it at its origin by the third nerve, which comes forwards be-
tween the two vessels. It turns backwards round the crus cerebri, and then
runs outwards and upwards on the under surface of the posterior lobe of the
cerebrum, passing near the posterior extremity of the corpus callosum. It
divides beneath the posterior lobe into many branches, which, ramify upon
the under, median, and outer surfaces, and anastomose with tlie other
cerebral arteries.
BRANCHES. Immediately after its origin the posterior cerebral artery gives off
numerous small parallel branches, which perforate the substance of the brain between
the crura, at the point which is called from this circumstance the posterior perforated
spot. As it turns backwards, a short distance from its origin, this artery is joined
by the posterior communicating artery, and in this way contributes as already
described (p. 363) to form the circle of Willis. Lastly, the posterior cerebral gives
origin to a small branch, the posterior choroid, which, arising external to the junction
of the communicating artery, turns backwards over the crus cerebri and the tubcr-
cula quadrigemina, supplying these with branches, and ending in the velum inter-
positum and choroid plexus in the interior of the brain.
PECULIARITIES. Traces of a septum are sometimes found in the interior of the
basilar artery. (Davy, " Researches," &c., vol. i. p. 301.) This trunk has also been
found perforated by a small foramen, owing to a partial fissuring of the vessel along
the median line.
THYROID AXIS. 371
The posterior cerebral artery is occasionally given off on one side from the internal
carotid artery.
II. THYROID AXIS.
The thyroid axis springs from the fore part of the subclavian artery,
close to the inner side of the anterior scalenus muscle. It is a short thick
trunk, and receives the name of " axis," because, at a line or two from its
origin, it divides into branches, which diverge in different directions, viz.,
the inferior or ascending thyroid, the suprascapular, and a third branch,
which is either the transverse cervical, or one of the branches into which
that artery, when present, divides, viz., the superficial cervical.
PECULIARITIES. The thyroid axis has been known to arise beyond the scalenus
anticus muscle. It may be associated at its origin with another branch ; thus, it
sometimes gives origin to the internal mammary, and has been known to give origin
to the vertebral, superior intercostal, or deep cervical arteries.
1. THE INFERIOR THYROID ARTERY passes directly upwards, resting on
the longus colli muscle, and after a short course bends inwards and down-
wards behind the sheath of the large cervical vessels, and also behind the
sympathetic nerve (the middle cervical ganglion of which, when present,
often rests upon this vessel). The artery then makes another carve in the
opposite direction, and is distributed to the under part of the thyroid
body. Its branches communicate freely with those of the superior thyroid
artery, and with the corresponding artery of the other side.
BRANCHES. (a) The ascending cervical branch arises at the point where the
inferior thyroid turns inwards behind the carotid artery ; it proceeds upwards, close
to the phrenic nerve, on the line of separation between the scalenus anticus and
rectus anticus major, giving muscular branches to both, and a few which pass trans-
versely outwards across the neck. These muscular branches communicate with others
sent outwards from the vertebral artery. To the spinal canal the ascending cervical
artery sends one or two branches (spinal branches), which enter the inter vertebral
foramina along the cervical nerves, and assist in supplying the bodies of the vertebrae,
and the spinal cord and its membranes.
(b) A laryngeal branch of irregular size is usually supplied by the inferior thyroid
artery ; it ascends on the trachea and the back of the larynx, and is distributed to
the muscles and mucous membrane in that situation.
(c) Traclieal branches ramify over the trachea, and anastomose below with the
bronchial arteries.
(d) (Esophageal branches are given off, and one or more descend upon the trachea
into the chest.
PECULIARITIES. Origin. The inferior thyroid artery occasionally arises as an
independent branch from the subclavian artery, and rarely from the common carotid
or the vertebral. Instances have occurred very rarely, however of the presence of
two inferior thyroid arteries, one passing over the common carotid artery.
The ascending cervical artery is occasionally derived from the subclavian or from
one of the branches of that vessel, as from the transverse cervical or the suprascapular,
or from a trunk common to those two arteries. It is sometimes much larger than
usual, and takes the place of the occipital artery. A branch from it not unfrequently
compensates for the small size of the deep cervical artery.
2. THE SUPRASCAPULAR ARTERY (transverse scapular, or transverse
humeral), a smaller vessel than the transverse cervical, arises almost
constantly from the thyroid axis, and runs from within outwards deeply at
the root of the neck. At first it descends obliquely towards the clavicle,
resting upon the scalenus anticus, and covered by the sterno-mastoid
372
SUBCLAVIAN ABTERIES.
muscle ; it then crosses the subclavian artery, and continues transversely
outwards behind and parallel with the clavicle and subclavius muscle,
and below the posterior belly of the omo-hyoid muscle. Approaching the
upper margin of the scapula, under cover of the trapezius muscle, it inclines
Fig. 264. VIEW OP
THE ANASTOMOSES
OP ARTERIES ON
THE SHOULDER
AND DORSUM OP
THE SCAPULA (from
Tiedemann).
a, sterno-mastoid
muscle ; b, trapezius
turned towards the
left side; c, splenius
capitis, and below it
splenius colli ; d,
levator anguli sca-
pulaa ; e, serratus
posticus superior ; /,
rliomboideus minor,
and g, rhomboideus
major, divided from
the base of the sca-
pula; h, teres major,
i, teres minor ; A',
scapular head of the
triceps brachii ; I,
serratus magnus; n,
deep surface of the
deltoid muscle turned
down ; o, portion of
the iufraspiuatus
muscle attached to
the great tuberosity
of the humerus, the
rest having been re-
moved from the in-
fraspinal fossa ; 1,
occipital artery ap-
pearing between the
trapezius and sterno-
mastoid muscles ; 2,
superficial cervical
branch of the trans-
verse cervical artery ;
2', 2', posterior sca-
pular artery ; 2+,
its supraspinous
branch ; 3, supra-
scapular artery ; 3',
the same after pass-
ing tli rough the sca-
pular notch into the
infraspinons fossa,
Avhere it anastomoses
with 4, the dorsal
branch of the subscapular artery ; 4', inferior scapular branch of the snbscapular ; 4",
some of the descending thoracic branches of the subscapular artery ; 5, posterior circumflex
artery emerging from the quadrangular space, and sending branches upwards on the
shoulder-joint, round the humerus, and downwards into the deltoid muscle ; 6, anasto-
mosis of the acromial branches of the suprascapular with the acromio-thoracic artery.
SUPRA-SCAPULAR. TRANSVERSE CERVICAL. 373
downwards with the suprascapular nerve towards the suprascapular notch.
At this point the nerve usually passes beneath the ligament stretched across
the notch, while the artery more frequently turns over it to enter the supra-
spinous fossa, where, lying close to the bone, it gives off branches which
ramify in the fossa beneath the supraspinatus muscle, and sends a small
communicating branch into the subscapular fossa, and is itself continued
down iuto the infraspinous fossa.
BRANCHES. Muscular branches are given by the suprascapular artery to the
sterno-mastoid and other neighbouring muscles.
(b) The supra-acromial branch passes obliquely forwards through the attachment
of the trapezius to reach the cutaneous surface of the acromion, on which it ramifies,
anastomosing with offsets from the acromial thoracic artery.
(c) A small subscapular branch, given off as the artery passes over the notch,
anastomoses with the posterior scapular and subscapular arteries in the subscapular
fossa and substance of the subscapularis muscle..
(d) An infraspinous branch is continued from the suprascapular artery, and
descending close upon the neck of the scapula, between the glenoid cavity and the
spine of that bone, joins with the dorsal branch of the subscapular artery.
(e) Branches enter the bone and shoulder joint.
PECULIARITIES. The suprascapular artery has in some cases been observed to
spring directly from the subclavian, or to arise from that vessel by a common trunk
with the transverse cervical, or more rarely with the internal mammary. It has
also been found to proceed from the axillary artery, and from the subscapular branch
of that vessel.
3. THE TRANSVERSE CERVICAL ARTERY, the third branch of the thyroid
axis, passes outwards a short distance above the clavicle, and therefore
higher than the suprascapular artery. It crosses over the scaleni muscles
aud the brachial plexus, sometimes passing between the nerves of the latter,
and is crossed by the omo-hyoid muscle. Beneath the anterior margin of
the trapezius, and near the outer edge of the levator anguli scapulae, it
divides into two branches, the superficial cervical and the posterior
scapular.
The superficial cervical artery ascends beneath the anterior border of the
trapezius, and distributes branches to that muscle, the levator auguli scapulae,
and sterno-mastoid muscles, as well as to the cervical glands and the
integuments in the intervals between those muscles, When the posterior
scapular arises separately from the subclavian, the name superficial cervical
may be given to the whole remaining part of the transverse cervical artery.
The posterior scapular artery, whether arising from the transverse cervical
artery or directly from the subclavian, passes backwards to the upper angle
of the scapula, under cover of the levator anguli scapulas, and then changing
its direction, runs downwards beneath the rhomboid ei muscles, as far as the
inferior angle of that bone. It anastomoses freely on both surfaces of the
scapula with the divisions of the suprascapular and subscapular arteries;
and supplies branches to the rhomboidei, serratus magnus, and latissimus
dorsi muscles, communicating at the same time with the posterior muscular
branches of some of the intercostal arteries.
PECULIARITIES. Not only does the transverse cervical branch of the thyroid axis
present the variation of being nearly as often the superficial cervical alone as of com-
prising also the posterior scapular artery, but it occasionally happens that the vessel
derived from the thyroid axis is very small, and represents only in part the superficial
cervical artery ; whilst a large vessel arising | from the third part of the subclavian
divides near the levator anguli scapulae into two branches, of which one ascends and
374 SUBCLAVIAX ARTERIES.
represents tlie remaining and larger portion of the superficial cervical artery, while
the other forms the posterior scapular.
The transverse cervical artery is sometimes derived directly from the subclavian,
beneath or even beyond the scalenus anticus muscle. The transverse cervical some-
times gives off the ascending cervical artery.
When the superficial cervical is separated from the posterior scapular, it sometimes
arises from other sources than the thyroid axis, as from the suprascapular or the
subclavian artery.
III. INTERNAL MAMMARY ARTERY.
The internal mammary artery, remarkable for its length and the number
of its branches, arises from the under side of the subclavian, opposite the
thyroid axis. It runs forwards and downwards behind the clavicle to the
inner surface of the cartilage of the first rib, lying between this and the sac
of the pleura : from this point it inclines a little inwards, and then descends
vertically behind the costal cartilages, a short distance from the border of
the sternum, as far as to the interval between the sixth and seventh
cartilages, where it ends by dividing into two branches. One of the
branches into which the artery divides, musculo-phrenic, inclines outwards
along the margin of the thorax; while the other, under the names of
abdominal or superior epigastric, continues onwards to the abdomen in the
original direction of the trunk.
Covered at its origin by the internal jugular vein, like the other large
branches of the subclavian artery, the internal mammary soon passes behind
the subclavian vein, and is crossed in front by the phrenic nerve which lies
between the vein and the artery. In the chest it has the costal cartilages
and the internal intercostal muscles in front, and lies at first upon the
pleura; but lower down it is separated from the pleura by the triangularis
sterni muscle. This artery has two companion veins, which are united into
a single trunk at the upper part of the chest.
BRANCHES. The branches of this artery are numerous, and are distributed chiefly
to the walls of the chest and abdomen.
(a) The superior phrenic or comes nervi plirenici, a very slender but long branch,
arises high in the chest, and descends with the phrenic nerve, between the pleura and
the pericardium, to the diaphragm, in which it is distributed, anastomosing with
offsets from the musculo-phrenic and with the inferior phrenic arteries from the ab-
dominal aorta.
(/>) The mediastinal or tliymic branches, of very small size, ramify in the loose con-
nective tissue of the mediastinal space, and supply the remains of the thymus body,
which, when in full development, receives its principal branches from the internal
mammary artery. Pericardiac branches are given off directly to the upper part of
the pericardium, the lower part of which receives some from the musculo-phrenic
division. Branches named sternal are also supplied to the triangularis sterni muscle,
and to both surfaces of the sternum.
(c) The anterior intercostal arteries, two in each space, arise from the internal
mammary, either separately, or by a trunk common to the two, which soon divides.
The arteries pass outwards, at first between the pleura and the internal intercostal
muscles, and afterwards between the two layers of intercostals ; they lie, one near
the upper and one near the lower rib, in each of the upper five or six intercostal
spaces, and inosculate with the corresponding intercostal branches derived from the
aortic intercostals. These branches supply the intercostal and pectoral muscles, and
give some offsets to the mamma and integument.
(d) The anterior or perforating branches pass forwards from the internal mammary
artery through from four to six intercostal spaces, and turning outwards ramify
partly in the pectoralis major, and partly in the integument on the front of the chest.
INTERNAL MAMMARY ARTERY.
375
Those placed nearest to the mammary gland supply that organ, and in the female
they are of comparatively large size, especially during lactation. Some offsets ramify
on the sternum.
Fig. 265.
Fig. 265. DISSECTION OF THE RIGHT SIDE
OF THE ANTERIOR THORACIC AND AB-
DOMINAL WALL, TO SHOW THE ANASTO-
MOSES OF THE INTERNAL MAMMARY,
INTERCOSTAL, AND EPIGASTRIC VESSELS
(slightly altered from Tiedemann).
The pectoral part of the serratus mag-
nus, the external aud internal ob-
lique, and the rectus abdoninis muscles,
have been removed ; 1, upon the subclavius
muscle, points to the first part of the
axillary artery above the pectoralis minor
muscle, giving rise to the acromio-thoracic
artery, which is cut short ; 2, upon the
pectoralis minor, points to the lower part
of the axillary artery and vein ; 3, the
long thoracic artery ; 4, on the cartilage of
the first rib, marks the upper part of the
internal mammary artery ; 4', the lower
part of the same artery giving its abdominal
branch behind the cartilage of the seventh
rib ; 5, in the fourth intercostal space,
marks the anastomosis of the internal
mammary and intercostal arteries ; 6,
anterior branches of the internal mam-
mary artery ramifying over the front of the
sternum ; 7, on the trans versalis muscle
immediately above the internal inguinal
aperture, points to the last part of the ex-
ternal iliac artery, from which are seen
rising, 8, the deep epigastric artery, and
9, the deep circumflex iliac ; 10, the anas-
tomosis of the epigastric with the abdomi-
nal branch of the internal mammary
artery ; 11, the spermatic cord and sper-
matic twig of the epigastric artery ; 12,
the femoral artery giving small twigs to
the groin and the superficial pudic vessels ;
13, the femoral vein; 14, a lymphatic
gland closing the femoral ring.
(e) The musculo-plirenic artery, the
outer of the two branches into which the
internal mammary artery divides, in-
clines downwards and outwards behind
the cartilages of the false ribs, perforating
the attachment of the diaphragm at the
eighth or ninth rib, and becoming gra-
dually reduced in size as it reaches the
last intercostal space. It gives branches
backwards into the diaphragm; others,
which pass outwards to form the anterior
intercostals of each space, and are dis-
posed precisely like those which are derived higher up from the main internal mam
mary ; and some which descend into the abdominal muscles.
(/) The abdominal branch or superior epigastric artery of the internal mammary,
descending into the wall of the abdomen, lies behind the rectus, between the muscle
and its sheath ; and afterwards, entering the muscle, terminates in its substance, at
376 SUBCLAVIAN ARTERIES.
the same time anastomosing with the epigastric artery. It also supplies twigs to the
broad muscles of the belly, to the skin, and to the diaphragm ; and one runs forwards
upon the side and front of the xiphoid cartilage, where it anastomoses with that of
the opposite side.
PECULIARITIES. The internal mammary is occasionally found connected at its
origin with the thyroid axis, or with the scapular arteries these being detached
from the thyroid. It occasionally springs from the second or third part of the sub-
clavian artery (the latter being the more frequent position of the two). In very rare
instances it has been found arising from the axillary, the innominate, or the aorta.
An unusual branch, of considerable size, occasionally comes off from it, and passes
downwards and outwards, crossing several of the ribs, on their inner surface, in
contact with the pleura. The internal mammary artery may likewise furnish a
bronchial branch.
IV. SUPERIOR INTERCOSTAL AND DEEP CERVICAL ARTERIES.
THE SUPERIOR INTERCOSTAL artery generally arises from the upper and
back part of the subclavian, behind the anterior scalenus muscle on the right
side, and immediately at the inner side of the muscle on the left side.
Taking its course backwards, it speedily gives off the deep cervical branch
(profunda cervicis), and bending backwards and downwards in front of the
iieck of the first rib, ends in one or two intercostal spaces : on the right
side it more frequently descends into the second space than on the left side.
On the neck of the first rib, the artery is situated on the outer side of the
first dorsal ganglion of the sympathetic nerve.
BRANCHES. Besides giving off the deep cervical artery, the superior intercostal
gives branches to the first and second intercostal spaces. The branch to the first
space is similar in course and distribution to the aortic intercostals : that to the
second space usually joins with one from the first aortic intercostal. A small offset is
likewise sent backwards, through the first space, to the posterior spinal muscles, and
also a small one through the corresponding intervertebral foramen to the spinal cord
and its membranes.
PECULIARITIES. Origin. The superior intercostal artery has been found, in a few
instances, to proceed from the vertebral artery or from the thyroid axis.
Course. It has been observed to pass between the necks of one or two ribs and the
corresponding transverse processes of the dorsal vertebrae ; and a case has been
recorded in which, after arising from the vertebral artery, it descended through the
intertransverse foramen of the last cervical vertebra, and then continued, as in the
instances just mentioned, between the necks of the ribs and the contiguous trans-
verse processes of the vertebrae of the back. (Quain on the Arteries, plate 22, fig. 5.)
The intercostal artery is sometimes, though very rarely, wanting.
THE DEEP CERVICAL artery, often described as a separate branch of the
subclavian artery, arises in most cases from the superior intercostal. Re-
sembling the posterior branch of an aortic intercostal artery, it generally
passes backwards in the interval between the transverse process of the last
cervical vertebra and the first rib, to reach the posterior aspect of the neck.
Here it ascends in the interval between the transverse and spinous processes,
as high as the second vertebra, under cover of the complexus muscle,
between this and the semi-spinalis colli. Some of the branches communi-
cate with those given outwards by the vertebral artery, whilst others
ascend to anastomose with the cervical branch of the occipital artery.
PECULIARITIES. Origin. The deep cervical artery sometimes arises from the sub-
clavian, and more rarely from the posterior scapular. It is not unfrequently supple-
mented by a branch turning backwards from the ascending cervical artery beneath
the transverse process of the third cervical vertebra, or by another branch from the
superior intercostal, or, in some instances, by a twig from the posterior scapular or
inferior thyroid arteries.
AXILLARY ARTERY. 377
Course. This artery occasionally passes back between the sixth and seventh
cervical vertebrae, and sometimes between the first and second dorsal, or even below
the second. It has been seen to pass between the first rib and the transverse process
which supports it.
AXILLARY ARTERY.
The axillary artery, that part of the artery of the upper limb which
intervenes between the subclavian aiid the brachial portions, extends from
the outer border of the first rib to the lower margin of the tendons of the
latissimus dorsi and teres major muscles. In this course it passes through
the axilla, and its direction varies with the position of the limb, being
curved downwards or upwards, or being straight, according as the arm
hangs by the side, or is elevated, or extended.
In front, the axillary artery is covered by the pectoralis major muscle,
behind which it is crossed by the pectoralis minor. It may be conveniently
divided into three parts : the first part lying internal to the pectoralia
minor muscle, and resting on the thoracic wall; the second part behind
that muscle, and passing from the thorax towards the shoulder ; the third
part beyond the muscle, and resting on the humerus.
In the first part of its course the vessel is in contact with the serratus
magnus muscle on its inner side, and is covered by the costo-coracoid mem-
brane, which, attached above to the clavicle, is continued below into a
common sheath investing the artery and vein, and completed behind by a
prolongation of the deep cervical fascia. In this part of its course the
artery is placed with the trunks of the brachial plexus above and behind it,
and the axillary vein in front of it and somewhat nearer the thorax : it is
also crossed by the cephalic and acromio-thoracic veins as they dip down to
terminate in the axillary vein.
In the second part of its course, behind the pectoralis minor, the axillary
artery is completely surrounded by the trunks of the brachial plexus, and
it is crossed in front by one of the roots of the median nerve : the vein is on
the thoracic side of the artery, separated from it by nerves.
In the third part of its course, beyond the pectoralis minor, the axillary
artery rests on the subscapular muscle and the insertions of the latissimus
dorsi and teres major, while to the outer side is the coraco-brachialis muscle.
The axillary vein is still on the thoracic side, but sometimes the venae
comites, by whose union it is formed, are continued up to this level, one on
each side of the artery. The main branches resulting from the division of
the brachial plexus of nerves are disposed behind and on each side of this
part of the artery, as follows, viz., behind it, the circumflex and musculo-
spiral ; to its inner side, the ulnar and the two internal cutaneous ; to the
outer side, the external cutaneous and median. The external cutaneous
and the circumflex nerves leave the artery in the axilla, and at the lower
part of the axilla the median nerve is often before the vessel; in an opera-
tion, that nerve might serve as a guide to the position of the artery, for it
could be distinguished from the other large nerves (ulnar and musculo-
spiral) by the circumstance of its being the nearest to the pectoral muscle.
Beyond the border of the pectoralis major, the artery is covered only by
the skin and fascia on the inner side ; and here the flow of blood may be
controlled by pressure of the finger directed outwards against the humerus.
BRANCHES. The branches of the axillary artery consist of the external
thoracic branches furnished to the muscles of the chest, the subscapular
378
AXILLARY ARTERY.
Fig. 266.
Fig. 266. DEEP VIEW OF THE CAROTID, SUBCLAVIAN, AND AXILLARY ARTERIES (from
Tiedemann). ^
The great pectoral, the sterno-mastoid, and the sterno-hyoid and sterno-thyroid muscles
have been removed ; the front part of the deltoid has been divided near the clavicle : the
greater part of the digastric muscle has been removed, and the upper part of the splenhis
capitis and trachelo-mastoid divided near the mastoid process. Subdavian Artery and
its Branches. 1, First or inner part of the subclavian artery giving rise to the thyroid
axis and internal mammary, and also to +, the vertebral artery; 2, third part of the
EXTERNAL THORACIC BRANCHES. 379
subclavian artery outside the sealenus anticus muscle ; 3, first part of the axillary artery
giving rise to the acromial thoracic, short thoracic, &c. ; 4, third part of the axillary artery
giving rise to the subscapular, circumflex, &c. ; 5, commencement of the brachial artery ;
6, transverse superficial cervical artery ; 6', placed on the sealenus anticus muscle, marks
the ascending superficial cervical branch ; 7, posterior scapular artery arising from the sub-
clavian artery behind the sealenus anticus muscle and separate from the thyroid axis ; 8,
acromial branches of the acromial thoracic ; 9, pectoral branches of the same; 10, long
thoracic artery outside the pectoralis minor muscle; +, posterior circumflex branch
of the axillary artery (the anterior circumflex is seen rising from the opposite side of the
same part of the axillary trunk) ; 11, subscapular artery passing between the subscapularis
and teres minor muscles to proceed to the lower angle and dorsum of the scapula ; 12,
thoracic descending branch of the subscapular artery. Carotid Artery and its Brandies.
13, lower part, and 14, upper part of the right common carotid artery ; 15, trunk of the
external carotid artery brought fully into view by the removal of the digastric muscle ;
16, trunk of the internal carotid artery; 17, 17, the thyroid axis of the subclavian
artery, and the inferior thyroid artery where it is distributed in the gland ; 18, superior
thyroid artery anastomosing in the gland with the inferior thyroid ; 19, lingual artery
brought into view by the removal of the lower part of the hyoglossus muscle ; 20, facial
artery giving off the palatine, tonsillar, and submental ; 21, inferior labial ; 22, coronary
artery ; 23, occipital artery ; 24, posterior auricular artery ; 25, superficial temporal
artery ; 26, internal maxillary artery ; 27, transverse facial, given off in this instance
directly by the external carotid artery.
branch to the shoulder, and the anterior and posterior circumflex branches
to the upper part of the arm. The branches are not constant in their
number, size, or mode of origin.
EXTERNAL THORACIC BRANCHES. These branches vary much in number;
but, after the method of Haller, four are usually described.
1. The superior thoracic artery (thoracica suprema), a branch of incon-
siderable size, arises at a point internal to the pectoralis minor muscle, and
inclines dowriwards and inwards across the first two intercostal spaces,
anastomosing with the internal mammary and intercostal branches contained
in them, and terminates between the pectoral muscles.
2. The acromial thoracic artery (art. thoracica humeraria), of considerable
size, and by far the most constant of the thoracic branches of the axillary,
arises from its forepart at the inner border of the pectoralis minor muscle,
and soon divides into branches which take different directions.
(a) The acromial branches pass partly to the deltoid muscle and partly to the
upper surface of the acromion, and anastomose with the suprascapular and posterior
circumflex arteries.
(b) The humeral branch passes down in the interval between the pectoralis major
and deltoid muscles, accompanying the cephalic vein.
(c) The thoracic branches are distributed to the serratus magnus and pectoral
muscles, and anastomose with the other thoracic arteries.
(d) The clavicular branch, very small, passes inwards to the feubclavius muscle.
3. The long thoracic or external mammary artery is directed downwards and
inwards, along the lower border of the pectoralis minor, and is distributed
to the mamma, and to the serratus and pectoral muscles, and anastomoses
with the external branches of the intercostal arteries.
4. The alar thoracic branch is a very small vessel and not constant,
being frequently wanting, and having its place supplied by branches from the
thoracic and subscapular arteries. It is distributed to the lymphatic glands
and the fatty tissue in the axilla.
SUBSCAPULAR ARTERY. This branch, the largest given off by the axillary
artery, arises close to the lower border of the subscapular muscle, along
which it proceeds downwards and backwards, towards the inferior angle of
the scapula, accompanied by the subscapular nerve ; and it terminates in
c c 2
380
AXILLARY ARTERY.
branches to the subscapularis, serratus magnus, teres major, and latissimus
dorsi muscles. It soon becomes considerably diminished in size, owing to
its giving off a large branch to the dorsuin of the scapula. Its final ramifi-
cations anastomose with one another and with the branches of the posterior
scapular artery.
The dorsal branch (dorsalis scapulae) turns back from the subscapular
artery, about an inch and a half from its origin, and is sometimes larger
than the continuation of the vessel. Descending along the lower border of
the scapula, it passes through the interval bounded internally by the sub-
scapularis and teres minor, externally by the latissimus dorsi and teres
major, and superiorly by the long head of the triceps muscle ; and, turning
closely round the border of the scapula, which is frequently grooved to
receive it, passes between the teres minor and the bone, and ramifies in
the iufraspinous fossa, where it anastomoses with the suprascapular and
posterior scapular arteries.
Fig. 267.
V,
Fig. 267. VIEW
OF THE ARTERIES
WHICH RAMIFY AND
ANASTOMOSE ON THE
VENTRAL SURFACE
OF THE SCAPULA,
AND OF THE AN-
TERIOR CIRCUM-
FLEX ARTERY (from
B. Quain).
a, coracoid process ;
J, tendon of the long
head of the biceps
muscle emerging from
the bicipital groove ;
c, the front- of the
capsular ligament of
the shoulder -joint ; d,
tendon of the latissi-
mus dorsi muscle ; e,
teres major; 1, supra-
scapular artery de-
scending to the supra-
scapular notch, over
the ligament of which the larger part of the artery passes into the supraspinous fossa ;
A, A' the axillary and brachial artery ; 1', its subscapular branch passing through the
notch and ramifying in the subscapular fossa ; 2, 2, posterior scapular artery descending
parallel to the base of the scapula ; 2', its subscapular branches ; 3, main stem of the
subscapular artery at its origin from the axillary and continuation towards the dorsum of
the scapula ; 3' the branch to the ventral surface of the scapula proceeding to anasto-
mose with the subscapular branches of the suprascapular and posterior scapular arteries ;
4, descending or thoracic branch of the subscapular artery ; 5, anterior circumflex artery ;
6, posterior circumflex passing back through the quadrilateral muscular space.
The dorsalis scapulae gives off, (a) ventral branches, slender vessels which
ramify in the tmbscapular fossa between the subscapular muscle and the bone, and
anastomose with twigs from the suprascapular and posterior scapular arteries;
(6) branches to the teres muscles, and particularly a twig which descends between
their origins ; (c) terminal branches in the iufraspinous fossa.
CIRCUMFLEX ARTERIES. The posterior circumflex artery, a considerable
vessel but smaller than the subscapular, arises opposite the lower border of
the subscapular muscle, below the subscapular artery, and is directed back-
CIRCUMFLEX ARTERIES. BRACHIAL ARTERY. 381
wards in company with the circumflex nerve, passing through the space
between the teres muscles, the humerus, and the long head of the triceps
muscle, and therefore separated by the long head of the triceps from the
subscapular artery. It winds round the humerus, and terminates by rami-
fying in the deltoid muscle and on the shoulder-joint, and by anastomosing
with the anterior circumflex and suprascapular arteries, as well as with the
acromial thoracic.
The anterior circumflex, much smaller than the posterior circumflex,
arises nearly opposite to it or lower down, and from the outer side of the
axillary artery. It passes from within outwards and forwards, under the
inner head of the biceps and the coraco-brachialis muscle, resting on the fore
park of the humerus, until it reaches the bicipital groove. There it divides
into two branches, one of which ascends in the groove with the long head
of the biceps, to the head of the bone and the capsule of the joint ; the
other continues outwards, and anastomoses with the posterior circumflex
branch.
PECULIARITIES. The most important peculiarity in the trunk of the axillary artery
consists in its giving off a much larger branch than usual, an arrangement which
has been observed in the proportion of one out of every ten cases. In one set of
cases, this large branch forms one of the arteries of the fore-arm ; most frequently
the radial (about 1 in 33), sometimes the ulnar (1 in 72), and, rarely, the interosseous
artery (1 in 506 : R. Quain). In another set of cases, the large branch gives origin to
the subscapular, the two circumflex, and the two profunda arteries of the arm ; but
sometimes only one of the circumflex, or only one of the deep humeral arteries, arises
from it. In the second class of cases the divisions of the brachial plexus of nerves
surround the common trunk of the branches instead of the main vessel. This dis-
position may with probability be explained by supposing that the trunk of the branches
is the true brachial artery, but that in early life it has become obstructed below, and
that there has become developed in its place, as an apparent brachial artery for the
supply of the lower portions of the limb, a vas aberrans, such as is sometimes seen
arising from the brachial artery, and uniting with one of its branches.
The superior thoracic artery is so frequently given off by the acromio-thoracic, that
some anatomists have described that as the normal arrangement, giving the com-
mon trunk the name of thoracic axis. The long thoracic artery often arises from the
acromial thoracic, or is replaced by enlargement of the normal branches of that
artery, and not unfrequently is given off by the subscapular.
The dorsalis scapulae sometimes springs directly from the axillary artery.
The posterior circumflex artery is sometimes removed from the axillary to the
superior profunda branch of the brachial, in which case it ascends behind the tendons
of the latissimus dorsi and teres major. In another class of cases not quite so
numerous, the posterior circumflex gives off one or more branches usually derived
from other sources : as for example (placing them in the order of frequency), the
anterior circumflex, the superior profunda, the dorsal scapular, the anterior circum-
flex and superior profunda together, or some other rarer combination of those
vessels. The posterior circumflex is sometimes double ; and so is the anterior, but
more seldom.
BRACHIAL ARTERY.
The brachial or humeral artery, the continuation of the axillary, extends
from the lower border of the posterior fold of the axilla, to about a finger's
breadth below the bend of the elbow, or to a point opposite the neck of the
radius, where it divides into the radial and ulnar arteries. The vessel
gradually inclines from the inner side to the fore part of the limb, lying in
the depression along the inner border of the coraco-brachialis and biceps
muscles ; and its direction may be marked out by a line drawn from
382
BRACHIAL ARTERY.
midway between the folds of the axilla to the middle point between the
condyles of the humerus. To command the flow of blood through the
artery at its upper part, pressure should be directed outwards, while over
the lower end of the vessel the pressure should be made from before
backwards.
The brachial artery lies beneath the integument and fascia of the arm as
far as the bend of the elbow, where it sinks deeply in the interval between
the pronafcor teres and supiuator longus muscles, and is covered by the
fibrous expansion given from the tendon of the biceps to the fascia of the
fore-arm. It rests at first on the long head of the triceps muscle, the
musculo-ppiral nerve and the superior profunda artery intervening ; it then
inclines forwards over the insertion of the coraco-brachialis muscle, and lies
thence to its termination on the brachialis anticus. At its outer side it is
in apposition first with the coraco-brachialis, and afterwards and for the
Fig. 268.
Fig. 268. DISSECTION OP THE AXILLA AND INSIDE OP THE ARM TO SHOW THE
AXILLARY AND BRACHIAL VESSELS (from R. Quain).
The greater and lesser pectoral muscles have been divided so as to expose the axillary
vessels : a, the inserted portion of the pectoralis major; 6, the pectoral portion ; 1, ],
axillary artery ; + , + , the median nerve formed by the two portions of the plexus which
surround the artery ; 1', placed on a part of the sheath of the brachial vessels, and 1", on
the lower part of the biceps muscle, point to the brachial artery surrounded by its venpe
comites ; 2, 2, axillary vein ; 3, 3, the basilic vein ; the upper figure is placed on the
triceps muscle, the lower on the fascia near the junction of the ulnar vein : on the basilic
vein are seen the ramifications of the internal cutaneous nerve ; 4, on the deltoid, and 4',
on the clavicular part of the great pectoral muscle, mark the cephalic vein joining the
acromio-thoracic and through it the axillary vein ; 5, 5, placed on the divided portions of
the pectoralis minor, point to the origin and branches of the acromio-thoracic artery ; 6,
placed on a group of axillary glands, indicates the alar thoracic and subscapular vessels ;
7, placed on the trunk of the axillary vein, points by a line to one of the venae comites of
the brachial vein, which being joined by the other higher up passes into the axillary vein :
the ulnar nerve is seen passing from below the basilic vein towards the inner condyle ;
near 1 , placed on the coraco-brachialis muscle is seen the musculo-cutaneous nerve before
it passes through that muscle ; near 2, placed on the tendon of the latissimus dorsi
muscle, a portion of the nerve of Wrisberg.
BRACHIAL ARTERY. BRANCHES.
383
greater part of its length with the biceps, the inner border of one or both
muscles sometimes slightly overlapping it.
Relation to Veins. Venae comites are in close contact with the brachial
artery, short transverse branches of communication passing from one to
another, so as at many points to encircle it. Superficial to the aponeurosis,
the basilic vein is placed over or to the inner side of the artery in the lower
half or more, or in the whole length of its course, according to the level at
which the vein dips down to join the venae comites ; and at the bend of the
elbow the median basilic vein crosses over the artery, the aponeurotic inser-
tion of the biceps lying between them.
Relation to Nerves. The median nerve descends in contact with the
artery, lying on its outer side at the axilla, directly in front of it below the
middle of the arm, and on the inner side at the elbow. Of the large
branches of the brachial plexus which are closely connected with the axillary
artery, none continue in the immediate neighbourhood of the brachial
artery along the arm, except the median. The external cutaneous and
circumflex separate at once from the vessel in the axilla, the musculo-spiral
soon turns backwards in the musculo-spiral groove, and the internal
cutaneous and ulnar nerves descend vertically on the iuner side of the
limb.
Fig. 269.
Fig. 269. SUPERFICIAL DISSECTION OP THE
BLOOD-VESSELS AT THE BEND OP THE ARM
(from R. Quain). ^
a, two branches of the internal cutaneous
nerve ; a', a', the descending twigs of the same
nerve ; 6, placed over the biceps near its inser-
tion and close to the external cutaneous nerve ;
&', anterior twigs of the same nerve accompany-
ing the median vein ; 1, placed on the fascia of
the arm near the bend of the arm, above the
place where it has been opened to show the lower
part of the brachial artery with its vena? comites,
of which one is entire, marked 2, and the other
has been divided ; + , is placed between this and
the median nerve ; 3, basilic vein ; 3', 3', ulnar
veins ; 4, cephalic vein ; 4', radial vein ; 5, 5,
median vein ; 3', 5, median basilic vein ; 4', 5,
median cephalic vein.
BRANCHES. The brachial artery gives
some unnamed branches, which are di-
rected outwards and backwards to the
muscles in its immediate neighbour-
hood, viz. , to the coraco-brachialis, biceps,
,-md brachialis anticus. The following
branches, which incline inwards, have
received names, and require descrip-
tion.
(a) The superior profunda artery
(collateralis magna) arises from the inner
and back part of the brachial, just below tha border of the teres major,
and inclines backwards, to reach the interval between the second and
third heads of the triceps muscle. Accompanied by the musculo-spiral
nerve, it winds round the back of the huinerus, in the spiral groove, under
BEACHIAL AETEEY.
Fig. 270.
cover of the triceps, and perforating the
external intermuscular septum, reaches
the external and anterior aspect of the
bone. There the artery lies deeply in the
interval between the brachialis anticus
and supinator longus muscles, considerably
diminished in size by having given off
several branches, and descends to the
elbow, where it anastomoses with the
recurrent branch of the radial artery.
Fig. 270. SUPERFICIAL VIEW OF THE ARTERIES
OF THE ARM, FORE-ARM, AND HAND IN FRONT
(from Tiedemann).
, deltoid muscle ; &, biceps ; I', the aponeu-
rotic insertion ; c, scapular head of the triceps ;
e', its internal head ; d, pronator radii teres ; e,
flexor carpi radialis ; /, palmaris longus ; f, its
tendon spreading in the upper part of the palmar
fascia, from which, on the inner side, the pal-
maris brevis muscle is seen rising ; g, flexor
carpi ulnaris ; 7i, supinator radii longus ; i,
extensor carpi radialis longior ; I, extensor ossis
metacarpi pollicis ; m, flexor digitorum com-
munis sublimis ; 1, placed on the tendon of the
latissimus dorsi, the lower part of the axillary
aitery, continued into the brachial ; 2, superior
profunda ; 3, inferior profunda; 4, ulnar ana-
stomotic ; 5, near the division of the brachial
artery into ulnar and radial, and recurrent radial
artery ; 5', lower part of the radial artery, where
it gives off the superficialis vola?, and turns
round the wrist ; 6', the lower part of the ulnar
artery, near the place where it passes down to
form the superficial palmar arch ; 7, the super-
ficialis volae, which joins it ; 8, 8, 8, 8, first,
second, third, and fourth digital branches of the
superficial arch to the inside of the little finger,
adjacent sides of the 4th and 5th, 3rd and 4th,
and 2nd and 3rd fingers; 9, radialis indicis ;
on the thumb are seen the two branches of the
princeps pollicis artery.
The superior profunda gives off branches in
its first part to the deltoid, coraco-brachialis,
and triceps ; and many to the last-named mus-
cle, whilst it is between it and the bone. In.
this position it also gives one long branch,
which descends perpendicularly between the
muscle and the bone to the back part of the
elbow-joint on the outer side, where it anasto-
moses with the interosseous recurrent branch ;
and another which anastomoses on the inner
side with the ulnar recurrent and the anasto-
motic or the inferior profunda.
(6) The inferior profunda artery (col-
lateralis uluaris prim a), of small size,
arises from the brachial artery a little
below the middle of the arm, and is
BRANCHES OF THE BRACHIAL. PECULIARITIES. 386
directed to the back part of the iuner condyle of the humerus. Descending
in company with the uluar nerve, it pierces the intermuscular septum, theu
lies on the inuer surface of the triceps muscle, to which it gives branches,
and entering the interval between the olecranon and inner coudyle, it
terminates by inosculating with the posterior recurrent branch of the uluar
artery, and with the anastomotic branch of the brachial.
(c) The nutrient artery of the shaft of the humerus is a small branch
giveu off by the brachial about the middle of the arm, or by one of its
collateral branches. It inclines downwards, enters the oblique canal in the
humerus near the insertion of the coraco-brachialis muscle, and is distributed
in the interior of the bone.
(d) Ttie anastomotic artery (collateralis nlnaris secunda) is a very con-
stant branch of moderate size. Arising from the brachial artery about two
inches above the bend of the arm, it is directed transversely inwards on the
brachialis anticus muscle, above the inner condyle of the humerus, and, after
perforating the intermuscular septum, turns outwards behind the humerus,
between the bone and the triceps muscle, and forms with the superior pro-
funda an arch across the humerus, immediately above the olecranou fossa
(arcus dorsalis humeri posticus, Haller). In front of the humerus the
anastomotic artery furnishes a branch which ramifies in the pronator teres,
and anastomoses with the anterior ulnar recurrent branch. Behind the
inner condyle another offset joins with the posterior ulnar recurrent, and
behind the humerus several branches are given to the joint and the muscle.
PECULIARITIES. From their comparative frequency, and surgical interest, the
peculiarities of the brachial artery, especially those which affect its trunk, deserve
particular attention.
Course. The brachial artery sometimes lies in front of the median nerve, instead
of behind it.
The brachial artery has been seen, though rarely, to descend, accompanied by the
median nerve, towards the inner condyle of the humerus, and regain its usual position
at the bend of the elbow by passing forwards underneath a fibrous arch, from which
the pronator teres in those cases arises, and which descends to the inner condyle from
the occasional prominence called the supracondyloid process, as has been previously
described (p. 80). Sometimes this disposition occurs without the development of any
bony prominence.
As an extremely rare condition, the artery has been found divided into two vessels
near its commencement, the artery being single above and below, as also occurs with
the femoral trunk.
In a very few cases the three arteries of the fore-arm, radial, ulnar, and inter-
osseous, have arisen together from the end of the brachial trunk, at the usual distance
below the elbow.
High division. The most frequent change from the ordinary arrangement of the
brachial artery is connected with its division into terminal branches.
Out of 481 examples recorded by Richard Quain from observations made, some on
the right and some on the left side of the body, the vessel was found in 386 to divide
at its usual position, a little below the elbow-joint. In one case only (and that com-
plicated by another peculiarity, viz., the existence of a vas aberrans proceeding from
the axillary to the radial), was the place of division lower than usual, being between two
and three inches lower than the elbow-joint. In 64 cases the brachial artery divided
above the usual point, at various heights upwards to the lower border of the axilla.
The branch prematurely separated from the rest of the trunk in an early division, is,
in the proportion of nearly three cases out of four, the radial artery ; sometimes the
ulnar is the branch given off; that is to say, a branch corresponding to the ulnar in
its distribution below the middle of the fore-arm separates from a trunk which after-
wards divides into the normal radial artery and the interosseous of the fore-arm,
which last is normally derived from the ulnar artery. Rarely the interosseous of the
fore-arm, or a vas aberrans } is the branch given off.
386
BRACHIAL ARTERY.
Fig. 271.
In all cases of the high origin of one or other of the arteries of the fore-arm, the
extent in which the two vessels thus formed run separately must vary according to the
height at which the main artery divides. The point
of division in the entire number of cases, without
reference to the particular branch given off, is
most frequently in the upper, less so in the lower,
and least so in the middle third of the arm. But
the early division of the main artery of the upper
limb may, as mentioned in connection with the
varieties of the axillary artery, take place within
the axilla, in which case it follows that the brachial
portion of the vessel is replaced, throughout its
whole extent, by two separate trunks. In 94 cases
out of 481 observed by R. Quain, or about one in five
and one-ninth, there were two arteries instead of one
in some part or in the whole of the arm.
TJie position of the two arteries, in these cases,
is of much surgical interest. We shall here con-
sider only their position in the arm, and subse-
quently trace them in their irregular course in the
fore-arm. Usually they are close together, and
occupy the ordinary position of the brachial artery ;
but there are some peculiarities in their position
which require to be particularly noticed.
The radial artery, when thus given off in the
arm, often arises from the inner side of the brachial,
then runs parallel with the larger vessel (the bra-
chial or ulnar interosseous), and crosses over it,
sometimes suddenly, opposite the bend of the
elbow, still covered by the fascia. It has been
found, but in a very few instances only, to perforate
the fascia, and run immediately under the skin,
near the bend of the elbow.
Fig. 271. DISSECTION OP THE RIGHT ARM, SHOWING
AN EXAMPLE OF HIGH SEPARATION OP THE RADIAL
ARTERY FROM THE BRACHIAL, AND AN ENLARGED
MEDIAN ARTERY IN THE FORE- ARM (from Tiede-
mann). \
1, on the tendon of the latissimus dorsi, points to
the upper part of the brachial artery ; 2, the brachial
artery after giving off the radial ; 3, the radial rising
in the upper third of the arm and descending in its
usual situation in the fore-arm ; 3', its superficial
volar branch ; 4, the ulnar artery in its usual course,
forming at 5, the superficial palmar arch, from which
three of the palmar digital arteries and the princeps
pollicis take origin ; the radial supplying the branches
to the index finger and one side of the middle finger ;
6, the superior profuuda branch of the brachial artery ;
7, muscular branches ; 8, ulnar anastomotic ; 9, re-
current radial ; 10, anterior iuterosseous giving an
unusually large median branch which descends over
the wrist to unite with the superficial palmar arch.
When the ulnar is the branch given off high
from the brachial, it often inclines from the posi-
tion of the brachial, at the lower part of the arm,
towards the inner condyle of the humerus. This
vessel generally lies beneath the fascia as it
descends, and superficially to the flexor muscles
PECULIARITIES OF THE BEACHIAL AETERY.
387
It is occasionally placed between the integuments and the fascia ; and in a single
instance was found beneath the muscles. In one instance occurring in the dissect-
ing-room of the Glasgow University, the ulnar artery, given off from the humeral
at the middle of the arm, was observed to descend superficially behind the inner
condyle.
The interosseous, after arising from the axillary or brachial artery, is commonly
situated behind the main artery, and, on reaching the bend of the elbow, passes
deeply between the muscles, to assume its usual position in the fore-arm.
Lastly, when the radial has arisen high in the arm, the residuary portion of the
brachial (ulnar interosseous) has occasionally been observed descending, accompanied
by the median nerve, along the intermuscular septum towards the inner condyle of
the huinerus, as far as the origin of the pronator teres (which in the cases recorded
was found broader than usual), whence it turned outwards under cover of the muscle,
to gain the usual position at the^iniddle of the bend of the elbow.
Fig. 272. ABERRANT ARTERY, SEPARATING FROM THE Fig. 272.
BRACHIAL AT THE MIDDLE OF THE ARM, PASSING WITH
THE MEDIAN NERVE THROUGH THE INTERNAL INTER-
MUSCULAR SEPTUM, AND JOINING FARTHER DOWN
THE REGULAR ULNAR (from R. Quain).
a, biceps muscle ; b, triceps ; c, c, divided pronator
teres ; d, d, d', median nerve, diverted from its usual
course, and passing with the aberrant artery through
the internal intermuscular septum ; e, e, e, ulnar
nerve in its usual course; 1, brachial artery, giving
off an aberrant artery at the middle of the arm ;
2, the usual radial artery ; 3, aberrant artery, with
the median nerve twining round it, passing at 3'
through the internal intermuscular septum ; 3", the
same farther down, and communicating at 4' with the
first part of the normal ulnar artery, 4, given off
from the brachial.
The two arteries taking the place of the brachial
are in some instances connected near the bend of
the arm by an intervening trunk, which proceeds
from the larger (or ulnar interosseous) artery to the
radial or the radial recurrent, and varies somewhat
in its size, form, and course. More rarely the two
unusual arteries are actually re-united.
The aberrant arteries, " vas aberrantia," alluded
to in the preceding statement, are long slender ves-
sels, which arise either from the brachial or the
axillary artery, and end by joining one of the
arteries of the fore-arm, or one of their branches.
In eight cases out of nine, observed by Quain, this
unusual vessel joined the radial; in the remaining
case it joined the radial recurrent, which arose
irregularly from the ulnar artery. Monro and
Meek el have each seen one case in which the
aberrant vessel joined the ulnar. This peculiarity
may be regarded, perhaps, as an approach to that
condition in which there is division of the brachial
artery and subsequent connection of its two parts
by an intervening branch.
State of the arteries in both limbs. Inmost cases of the high division of the brachial
arteries the condition of the vessels is not the same in the right and left arms. In
61 bodies in which the high division existed, it occurred only on one side in 43 ; on
both sides, in different positions, in 13 ; and on both sides, in the same position, in
the remaining 5.
Branches. It has been already mentioned (p. 381) that the superior profunda
388
Fig. 273.
ULNAE ARTERY.
may give origin to the posterior circumflex
artery, and that its own origin is sometimes
transferred to a branch arising from the axillary
artery.
The inferior profunda is likewise occasionally
absent, and on that account has not been recog-
nised by some anatomists as a regular branch of
the brachial artery.
The anastomotic artery is sometimes much
reduced in size, and in that case the inferior
profunda takes its place behind the humerus.
Fig. 273. DEEP ANTERIOR VIEW OP THE AR-
TERIES OP THE ARM, FORE-ARM, AND HAND
(from Tiedemaun).
The biceps brachii, the pronator teres and mus-
cles rising from the inner condyle, the supinator
longus, the lower part of the flexor longus pollicis
and flexor profundus digitorura, the anterior an-
nular ligament of the carpus and the muscles of
the ball of the thumb, have been removed ; n, pro-
nator quadratus muscle ; 1, lower part of the
axillary artery continued into the brachial ; 2,
superior profunda branch ; 3, inferior profunda ;
4, ulnar anastomotic ; 5, upper part of the radial
artery and radial recurrent ; 5', lower part of the
radial artery giving off the superficialis volse
branch ; 5", the radial artery emerging from be-
tween the heads of the abductor indicis muscle ;
6, 6, the upper part of the ulnar artery with the
anterior aud posterior ulnar recurrent branches ;
6', the ulnar artery approaching the wrist and
descending into the superficial palmar arch which
has been cut short ; 6", the deep branch of the
ulnar artery uniting with the deep palmar arch ;
7 (marked only on one), three interosseous branches
from the deep palmar arch joining the palmar digital
arteries 8, 8, 8, which have been cut away from
their origin from the superficial arch to near their
division into the collateral digital arteries ; the
ulnar collateral of the little finger is represented
as rising in this instance from the deep ulnar
artery; 9, placed between the princeps pollicis and
radialis indicis branches of the radial artery ; 10,
lower part of the anterior interosseous artery
passing behind the pronator quadratus muscle ; 11,
anastomosis of the anterior carpal branches of the
radial and ulnar arteries with recurrent branches
from the deep palmar arch.
ULNAE, ARTERY.
The ulnar artery, the larger of the two
vessels into which the brachial divides, ex-
tends along the inner side of the fore-arm
into the palm of the hand, where, joining
a branch of the radial, opposite the mus-
cles of the thumb, it forms the superficial
palmar arch. In this course it inclines
at first downwards aud inwards, describing
a slight curve, the convexity of which is
directed inwards, and passes under cover of
ULNAE ARTERY. RECURRENT BRANCHES. 389
the superficial muscles arising from the inner condyle of the humerus,
viz., the pronator teres, flexor carpi radialis, palmaris longus, and flexor
sublhnis, until it reaches the flexor carpi ulnaris near the junction of the
upper with the middle third of the fore-arm ; at this point the artery comes
into contact with the ulnar nerve, which was previously separated from it by
a considerable interval, and changing its direction, descends vertically with
the nerve towards the inner border of the palm of the hand. Descending
along the radial border of the tendon of the flexor ulnaris muscle, the
ulnar artery reaches the outer or radial side of the pisiform bone, where,
still accompanied by the nerve, it passes over the cutaneous surface of the
anterior annular ligament of the wrist into the palm of the hand. Its
disposition in the hand will be separately described.
In the first half of its course through the fore-arm, the artery is deep-
seated, being covered by the muscles arising from the inner condyle of the
humerus which have been already enumerated. About the middle of the
fore- arm it is overlapped by the fleshy part of the flexor carpi uluaris ; but
below that, it becomes more superficial, being overlaid by the tendon of the
muscle, and covered by the skin, the fascia of the fore-arm, and a thin layer
of membrane by which the vessel is bound down to the muscle beneath. At
first the ulnar artery lies on the insertion of the brachialis anticus into the
coronoid process of the ulna; then on the flexor profuudus in the rest of
the fore-arm, and lastly, on the annular ligament of the carpus. Below the
point at which it emerges from under the flexor carpi ulnaris (or a little
below the middle of the fore-arm), the tendon of that muscle is on its inner
or uluar side.
Relation to Nerves. The median nerve lies immediately on the inner side
of the ulnar artery at its origin, but being directed down the middle of the
fore-arm it soon passes over the vessel, separated from it at the point of
crossing by the deep head of the pronator teres muscle. As the ulnar
nerve descends behind the inner condyle of the humerus, it is removed from
the ulnar artery by a considerable interval at the upper part of the fore- arm ;
but as the vessel inclines inwards, it approaches the nerve, and is accom-
panied by it in the lower half of its course the nerve lying close to its
inner side. A small branch of the uluar nerve descends upon the lower
part of the vessel.
Relation to Veins. Two veins (venae comites) accompany the uluar
artery, and are frequently united by branches crossing it.
BRANCHES. The ulnar artery gives off" in the fore-arm the anterior and
posterior recurrent, the iuterosseous, and several muscular branches. At
the wrist it gives off the anterior and posterior carpal branches.
RECURRENT BRANCHES. The anterior ulnar recurrent artery, a small
branch, arches inwards and upwards from the upper part of the ulnar artery,
running on the brachialis anticus muscle, and covered by the pronator teres,
both which muscles it partly supplies. On reaching the front of the inner
condyle, it anastomoses with the inferior profunda and anastomotic arteries,
derived from the brachial.
The posterior ulnar recurrent, larger than the preceding, comes off lower
down ; but not unfrequently the two vessels arise by a short common trunk.
The posterior recurrent runs inwards and backwards beneath the flexor sub-
limis, and then ascends behind the inner condyle. In the interval between
that process and the olecranon it lies beneath the flexor carpi ulnaris, and
passing between the heads of that muscle along the ulnar nerve, supplies
branches to the muscles, to the elbow-joint, and to the nerve itself. This
390
ULNAR ARTERY.
branch communicates with the inferior profunda, the anastomotic, and, over
the olecranon, likewise with the interosseous recurrent.
Fig. 274. Fig. 274. VIEW OF THE ANAS-
TOMOSKS OP ARTERIES NEAR
THE ELBOW-JOINT : A, FROM
BEFORE ; B, FROM BEHIND
(from 11. Quain). \
A. a, brachialis anticus mus-
cle^; b. external eondyloid
eminence covered by the supi-
nator radii brevis and the anas-
tomoses of the superior profunda
and radial recurrent arteries ;
c, ulnar nerve ; d, median
nerve ; e, musculo-spiral nerve ;
e\ its posterior interosseous
branch : its radial branch is
cut; /, oblique line of the
radius ; 1, brachial artery ; 2,
radial artery ; 3, ulnar artery ;
4, inferior profunda; 5, anas-
tomotic ; 6, anterior ulnar re-
current anastomosing with the
anterior descending branches of
the anastomotic ; 7, posterior
ulnar recurrent passing up be-
hind the inner eondyloid emi-
nence to anastomose with the
inferior profunda and posterior
branch of the anastomotic ; 8,
spiral branch of the superior
profunda ; 9, placed on the
tendon of the biceps muscle,
points to the radial recurrent
artery; 10, 10, iuterosseous
artery and its anterior branch.
B. a, a part of the brachialis anticus muscle : 6, external lateral ligament of the
elbow-joint; c, ulnar nerve; d, a small part of the musculo-spiral nerve; 1, superior
profunda artery ; 2, its branch to the triceps muscle ; 3, its spiral branch to the outer
condyle ; 4, its anastomosis with the recurrent radial artery ; 5, recurrent of the posterior
interosseous artery, passing up to anastomose with the preceding and with the anasto-
motic behind the joint ; 6, inferior profunda ; 7, posterior branch of the anastomotic
artery ; 8, anastomosis of the anastomotic and inferior profunda with the superior pro-
funda and the posterior interosseous recurrent ; 9, posterior ulnar recurrent artery pass-
ing up in the groove of the ulnar nerve to anastomose with the inferior profunda and
anastomotic.
INTEROSSEOUS ARTERY. The interosseous or common interosseous artery,
the next, and the largest branch of the uluar, is a trunk of considerable size,
about an inch in length, which arises below the bicipital tuberosity of the
radius, beneath the flexor sublimis, and passes backwards to reach the upper
border of the interosseous ligament, where it divides into the anterior and
posterior interosseous arteries.
The anterior interosseous descends upon the anterior surface of the inter-
osseous ligament, accompanied by the interosseous branch of the median
nerve and vense comites, and overlapped by the contiguous borders of the
flexor profundus digitorum and flexor longus pollicis muscles. It continues
its course directly downwards as far as the upper border of the pronator
quadratus muscle, then pierces the interoseeous ligament, and descends to
the back of the carpus.
BRANCHES OF THE IXTEROSSEOUS ARTERY. 391
The anterior interosseous artery gives off the folloAving branches :
(a) The artery of the median nerve, or the median artery, a long slender branch,
which accompanies the median nerve and sends offsets into its substance. This
artery is sometimes much enlarged, and in that case it presents several peculiarities
to be hereafter noticed.
(b) Muscular branches to the flexor profundus, flexor longus pollicis, and pronator
quadratus muscles.
(e) The nutrient arteries of the shafts of the radius and ulna, which, diverging from
one another, enter the oblique foramina in those bones to be distributed to the
medullary membrane in their interior.
(d) An anterior inosculating branch, given off before the artery pierces the inter-
osseous membrane, and descending beneath the pronator quadratus muscle to anas-
tomose with the anterior carpal arteries.
(e) Terminal twigs inosculating with the posterior carpal arteries.
The posterior interosseous artery passes backwards through the interval
left between the oblique ligament and the upper border of the interosseous
ligament, and continuing its course downwards along the fore-arm, covered by
the superficial layer of extensor muscles, gives branches to them and the
deep-seated muscles, and reaches the carpus considerably diminished
in size.
In addition to muscular branches, it gives off the following :
(a) The posterior interosseous recurrent, which passes directly upwards, covered by
the anconeus, to reach the interval between the olecranon and external condyle ; at
which place it divides into several offsets which anastomose with the superior profunda
and the posterior ulnar recurrent.
(6) Terminal branches, which anastomose with the posterior or terminal branch
of the anterior interosseous artery, and with the carpal branches of the radial and
ulnar arteries.
MUSCULAR BRANCHES of the ulnar artery are distributed to the muscles
in the course of the vessel along the fore-arm : some of these perforate the
interosseous ligament to reach the extensor muscles.
CARPAL BRANCHES. The posterior ulnar carpal branch, of variable size,
arises a little above the pisiform bone, and, winding back under the tendon of
the flexor carpi ulnaris, reaches the dorsal surface of the carpus beneath the
extensor tendons.
Its branches are the following.
(a) A branch anastomoses with the posterior carpal artery derived from the
radial, so as to form the posterior carpal arch; from this arch are derived the
second and third dorsal interosseous arteries, which descend on the spaces between
the third and fourth and the fourth and fifth metacarpal bones, and are reinforced
at the upper ends of those spaces by anastomoses with the posterior perforating
branches of the deep palmar arch.
(I) A branch runs along the metacarpal bone of the little finger. Sometimes this
metacarpal branch arises as a separate vessel, the posterior carpal being then very
small.
The anterior ulnar carpal branch is a very small artery, which runs on the
anterior surface of the carpus beneath the flexor profundus, anastomoses
with a similar offset from the radial artery, and supplies the carpal bones
and articulations.
PECULIARITIES. Origin. In the whole number of cases observed by Richard
Quain, the ulnar artery was found to deviate from its usual mode of origin, nearly in
the proportion of one in thirteen. The brachial artery was, more frequently than the
xillary, the source from which it sprang; indeed, the examples of its origin from the
main trunk at different pirts appeared to decrease in number in proportion as the
392
ULNAR ARTERY.
place of origin was higher up the artery. See on this subject the description of the
peculiarities of the axillary and brachial arteries, pp. 381 and 385.
Fig. 275. Fig- 275. ABNORMAL SUPERFICIAL ULNAR ARTERY
RISING HIGHER THAN USUAL FROM THE BRAOHIAL.
This figure has been taken from a pi-eparation in A.
Thomson's collection ; the drawing being planned after
that of a similar case represented by R. Quain. Tab.
xxxvi. Fig 1.
a, biceps muscle covered by the deep brachial fascia ;
6, the same fascia in the fore-arm, which has been
opened in a considerable extent to show the radial artery
subjacent to it ; c, median nerve ; d, ulnar nerve ; 1,
on the biceps muscle, points to the brachial artery after
having given off an uluar artery higher up, and dividing
at 1', into the radial artery and a deep vessel correspond-
ing to the interosseous and a part of the usual ulnar ;
2, on the supinator longus muscle, points to the
radial artery ; 3, 3, artery which is given off by the
brachial in the arm, and which descending upon the fascia
takes the place of the ulna at the wrist ; 3', the same
continued into the superficial palmar arch, giving off
digital branches nearly in the usual manner, and joined
by a branch from the radial, 4, the superficial volar ;
5, digital branches ; towai'ds the thumb a commu-
nication of the superficial arch with the princeps pollicis
exists.
Course. The position of the ulnar artery in the
fore-arm is more frequently altered than that of the
radial. When it arises in the usual way, the course
of this artery is not often changed ; but it has been
seen to descend apart from the tendon of the flexor
carpi ulnaris, instead of being close to its radial
border.
In cases of high origin, it almost invariably descends
over the muscles arising from the inner condyle of the
humerus, only one exception to this rule having been
met with. CR. Quain, plate 36, fig. 2.)
Most commonly it is covered by the fascia of the
fore-arm ; but cases also occur in which the vessel rests
on the fascia, and either continues in that position or
becomes subaponeurotic lower down, while the vessel
thus disposed is distributed after the manner of the
normal ulnar artery. The vessel from which the high
ulnar separates is afterwards divided into the radial
artery and the interosseous, the last of which is usually
derived from the ulnar ; it appears therefore probable
that the abnormal arrangement results from early
obstruction of the ulnar artery below the origin of the
interosseous, and the development of a superficial
vas aberrans, which unites the portion of vessel below
the obstruction with the axillary or brachial trunk. The
interosseous artery in such cases of abnormality thus
comprises not only the ordinary interosseous branch,
but likewise the portion of ulnar artery above the
obstruction ; and, in accordance with this view, we
find that the recurrent branches are derived from it.
As to size, the ulnar artery presents some peculiarities which, being accompanied
by deviations of an opposite and compensating character in the radial artery, will be
noticed with that vessel.
SUPERFICIAL PALMAR ARCH. 393
Branches. The anterior and posterior ulnar recurrent branches frequently arise
by a common trunk. One or both have been seen to arise from the brachial artery.
The anterior and posterior interosseous arteries are occasionally given separately
from the ulnar. The common interosseous trunk has been found to arise above its
ordinary situation, taking origin from the brachial, and even (but more rarely) from
the axillary artery. The anterior interosseous presents some striking varieties of
excess in its branches, usually connected with a deficiency in the radial or ulnar
arteries : the most important of these is enlargement of the median branch.
Median artery. The branch accompanying the median nerve is sometimes much
enlarged, and in such cases may be regarded as a reinforcing vessel. It is generally
a branch of the anterior interosseous, but sometimes of the ulnar ; and more rarely
a median branch has been met with descending from the brachial artery. Accom-
panying the median nerve beneath the annular ligament into the palm of the hand,
the median artery ends most frequently by joining the superficial palmar arch, some-
times by forming digital branches, in other cases by joining digital branches given
from other sources.
SUPERFICIAL PALMAR ARCH.
The superficial palmar arch or artery (arcus superficialis volse, Ha Her) is
the continuation of the ulnar artery into the hand. Changing its course near
the lower border of the annular ligament, this artery turns obliquely out-
wards across the palm of the hand towards the middle of the muscles of the
thumb, where it terminates by inosculating with a small branch of the
radial artery the superficial volar, generally passing through among the
muscles of the thumb. In its course across the hand, the palmar artery
describes a curve, having its convexity directed towards the fingers, and
extending downwards somewhat lower than a line on a level with the pha-
langeal articulation of the thumb.
The superficial palmar artery rests at its commencement on the annular
ligament of the wrist, and slightly on the short muscles of the little finger ;
then on the tendons of the superficial flexor of the fingers, and the divisions
of the median and ulnar nerves, the latter nerve accompanying the vessel
for a short distance. It is covered towards the ulnar border of the hand
by the palinaris brevis, and afterwards by the palmar fascia and the
integument.
BRANCHES. The branches given off by the superficial palmar arch, which
are generally numerous, are as follow.
(a) The deep or communicating branch arises from the ulnar artery at the
commencement of the palmar arch a little beyond the pisiform bone, sinks
deeply between the flexor brevis and the abductor of the little finger, and
inosculates with the palmar termination of the radial artery, thereby com-
pleting the deep palmar arch.
(6) Small branches, some following a retrograde course towards the annular
ligament, are given off to the parts in the palm of the hand from the upper
or concave side of the palmar arch.
(c) The digital branches, usually four in number, proceed downwards
from the convexity of the palmar arch to supply both sides of the three
inner fingers, and the ulnar side of the fore finger. The first digital branch
inclines inwards to the ulnar border of the hand, and, after giving minute
offsets to the muscles of the little finger, runs along the inner margin of its
phalanges. The second runs along the fourth metacarpal space, and at the
root of the fingers divides into two branches, which proceed along the con-
tiguous borders of the ring finger and little finger. The third is similarly
distributed to the ring finger and middle finger ; and the fourth to the
D D
394
ULNAR AND RADIAL ARTERIES.
latter and the index finger. The thumb and the radial side of the index
finger are supplied from the radial arttry.
Fig. 276.
Fig. 276. SUPERFICIAL DISSECTION OF THE LOWER
PART OF THE FOREARM AND THE HANI>, SHOWING
THE RADIAL AND ULNAR ARTERIES, THE SUPER-
FICIAL PALMAR ARCH, AND THE ACCOMPANYING
NERVES (from R. Quaiu);
a, placed on the deep fascia of the forearm, between
the tendons of the palniaris longus and flexor carpi
rudialis muscles ; b, points by a line crossing the
pisiform bone to the ulnar nerve ; c, points to the
styloid process of the radius and twigs of the radial
nerve ; 1, radial artery lying on the flexor longus
pollicis ; 1', the radial artery passing behind the
tendons of the extensor ossis metacarpi pollicis
and extensor prirai internodii pollicis ; 2, superh'cialis
voice branch piercing the short muscles of the thumb
and emerging below to join the superficial palmar
arch ; 3, external branch of the princeps pollicis ; 4,
radialis indicis ; a branch from the superficial arch is
set-n joining the internal branch of the princeps
pollicis ; 5, ulnar artery lying upon the flexor digi-
torum profundus ; 5', the same descending on the
anterior annular ligament to form the superficial
palmar arch ; 6, deep branch of the ulnar artery
passing between the abductor and flexor minimi
digit! to join the deep arch, accompanied by the deep
branch of the ulnar nerve ; 7, branch of the super-
ficial arch to the ulnar side of the little finger ; 8,
division of the common branch to the 4th and 5th
fingers ; 9, the same to the 3rd and 4th fingers ; 10,
the same to the 2nd aud 3rd fingers ; 7 and 8, are
accompanied by the digital branches of the ulnar
nerve, and 3, 4, 9, aud 10, by the branches of the
median nerve.
The digital arteries are placed at first super-
ficially to the tendon?, and then lie between
them, accompanied by the digital nerves as far as the clefts of the fingers,
where they are joined by the anterior iuterosseous arteries, branches of the
deep arch. On the sides of the fingers, each artery lies beneath the corre-
sponding nerve, and gives branches which supply the sheaths of the tendons
and the joints, some of them anastomosing across the front of the bones
with similar branches from the opposite side. At about the middle of the
last phalanx, the two branches for each finger converge and form an arch,
from which proceed numerous small offsets to supply the matrix of the nail
and all the structures at the tip of the finger.
[The peculiarities observed in the branches of the superficial palmar arch will be
noticed after the description of the deep arteries of the hand.]
RADIAL ARTERY.
The radial artery appears by its direction to be the continuation of the
brachial, although it does not equal the ulnar in size. It extends along the
front of the forearm as far as the lower end of the radius, below which it
RADIAL ARTERY.
turns round the outer border of the wrist, Fig. 277.
and descends to the back of the space be-
tween the metacarpal bones of the thumb
and fore finger : there it passes forwards
into the palm of the hand, and crosses to-
wards the inner side, so as to form the
deeper palmar arch. In consequence of the
changes in its course, the direction and
connections of the radial artery may be
separately described in the forearm, on the
wrist, and in the hand.
Fig. 277. DEEP ANTERIOR VIEW ofl THE AR-
TERIES OP THE ARM, FOREARM, AND HAND
(from Tiedemann). \
The biceps brachii, the pronator teres and mus-
cles rising from the inner condyle, the supinator
longus, the lower part of the flexor longus pol-
licis and flexor profundus digitorum, the anterior
annular ligament of the carpus and the muscles
of the ball of the thumb, have been removed ; n,
pronator quadratus muscle ; 1, lower part of
the axillary artery continued into the brachial ;
2, superior profunda branch ; 3, inferior pro-
fund a ; 4, anastomotic ; 5, upper part of the radial
artery and radial recurrent ; 5', lower part of the
radial artery, giving oif the superficialis voice
branch; 5", the radial artery emerging from be-
tween the heads of the abductor indicis muscle ;
6, 6, the upper part of the ulnar artery with the
anterior and posterior ulnar recurrent branches ;
6', the ulnar artery approaching the wrist and
descending into the superficial palmar arch which
has been cut short ; 6", the deep branch of the
ulnar artery uniting with the deep palmar arch ;
7 (marked only on one), three interosseous branches
from the deep palmar arch joining the palmar
digital arteries 8, 8, 8, which have been cut away
from their origin from the superficial arch to near
their division into the collateral digital arteries ;
the ulnar collateral of the little finger is represented
as rising in this instance from the deep ulnar ar-
tery ; 9, placed between the princeps pollicis and
radialis indicis branches of the radial artery ; 10,
lower part of the anterior interosseous artery f
passing behind the pronator quadratus muscle ; 11, 5~j
anastomosis of the anterior carpal branches of the
radial and ulnar arteries with recurrent branches
from the deep palmar arch.
395
In the forearm the radial artery, com-
mencing at the point of bifurcation of the
brachial opposite the neck of the radius,
descends at first somewhat obliquely out
wards in a line with the brachial artery,
and then nearly vertically along the outer
part of the front of the forearm to the
fctyloid process of the radius. Its course
may be indicated by a line drawn from
D D 2
RADIAL ARTERY.
Fig, 278. the middle of the bend of the elbow to the
narrow interval between the trapezium bone
and the tendons of the extensors of the
thumb, which can be readily felt on the
outer border of the wrist.
-TV
Fig. 278. ARTERIES OF THE OUTER AND BACK
PART OF IHE ARM AND HAND, SUPERFICIAL
VIEW (from Tiedemann).
a, deltoid muscle ; &, external humeral head of
triceps ; c, biceps brachii ; d, brachialis anticus ;
e, supinator longus ; /, extensor carpi radialis
longior ; g, brevior ; A, extensor communis digi-
torum and extensor minimi digiti ; i, extensor
carpi ulnaris ; Jc, anconeus ; Z, flexor carpi ulnaris ;
m, extensor ossis metacarpi pollicis ; , extensor
primi iuternodii pollicis ; 0, tendon of the extensor
secundi internodii pollicis ; 1,1, branches of
superior profunda artery appearing between the
triceps and brachialis anticus, and descending 011
the outer supracondyloid eminence to anastomose
with the branches of the recurrent radial artery ;
2, above the posterior annular ligament points to
the posterior carpal branch of the interosseous
artery ; 3, posterior carpal branch of the ulnar
artery ; 4, radial artery taking its course between
the outer lateral ligament of the wrist-joint and
the tendons of the extensor muscles before passing
near 5, between the two heads of the abductor
indicia : beneath the extensor tendons is seen the
posterior carpal arch, giving the third and fourth
dorsal interosseous arteries ; 6, the inner dorsal
artery of the thumb ; 7, the outer dorsal artery
of the index finger, and between 7, and 7', the
remaining dorsal digital vessels in the spaces
between the heads of the metacarpal bones, near
their communications with the palmar digital
vessels.
The radial artery is nearer to the surface
than the ulnar, and is covered only by
the common integument and fascia, except
where it is overlapped by the fleshy part of
the supinator lougus, which must be drawn
aside in order to bring the vessel into view.
At first it is in contact with the tendon of
the biceps, and is supported by the fatty
tissue contained in the hollow in the front
of the elbow, which separates it from the
short supinator muscle. It then rests in
succession on the insertion of the pronator
teres, the thin radial origin of the flexor
sublimis, the flexor pollicis longus, the
pronator quadratus, and the lower end of
the radius. It is at this last point that
the pulse is usually felt during life. To
the inner side of this vessel lie the pronator
teres in the upper part of its course, and
BRANCHES OF THE RADIAL ARTERY. 397
the flexor carpi radialis in the remainder ; and on the outer side, in its whole
course along the forearm, is the supinator longus muscle.
Relation to Veins. The artery is accompanied by venae comites, which
have the usual arrangement of those veins.
Relation to Nerves. The radial branch of the musculo- spiral nerve is
placed on the outer side of the artery in the middle third of its course. At
the elbow that nerve is separated from the artery by a considerable interval ;
and towards the lower end of the forearm it turns backwards beneath the
tendon of the supinator longus, to reach the dorsal aspect of the limb, and
thus loses all connection with the artery. Some filaments of the external
cutaneous nerve pierce the fascia to reach the lower part of the artery,
which they accompany to the back of the carpus.
At the wrist the radial artery turns outwards between the styloid process
of the radius and the carpus, beneath the tendons of the extensors of the
metacarpal bone and first phalanx of the thumb, and upon the external
lateral ligament of the wrist-joint, to reach the back of the carpus. It then
runs downwards for a short distance, is crossed by the tendon of the
extensor of the second phalanx of the thumb, and, reaching the upper end of
the space between the first and second metacarpal bones, turns forwards
iuto the palm of the hand, by passing between the heads of the first dorsal
interosseous muscle.
As it turns round below the end of the radius the artery is deep-seated,
but afterwards conies nearer to the surface. It is accompanied by two
veins and by some filaments of the external cutaneous nerve, and is crossed
by subcutaneous veins and by filaments of the radial nerve.
BLANCHES. The branches of the radial artery may be arranged according
as they are given off in the forearm, on the wrist, and in the hand.
A. The branches which arise from the radial in the forearm are the
radial recurrent, the muscular branches, the anterior carpal, and the
superficial volar.
(a) The radial recurrent artery, which varies much in size, arches upwards
from the radial soon after its origin, running between the branches of the
musculo-spiral nerve. It first lies on the supinator brevis, and then on the
brachialis anticus, being covered by the supinator longus. In front of the
outer condyle, and in the internal between the two last muscles, it anasto-
moses with the terminal branches of the superior profuuda.
From the lower or convex side of this artery are given off several branches ; one,
of considerable size, to the supinator and extensor muscles, and some beneath the
latter to anastomose with the posterior interosseous branches. It also supplies the
supinator brevis and brachialis anticus in part.
(6) The anterior radial carpal is a small branch which arises from the
radial artery, near the lower border of the pronator quadratus, and runs
inwards in front of the radius. It anastomoses with the anterior ulnar
carpal artery, so as to form an arch above and in front of the radio-carpal
articulation, from which branches descend to supply the joints at the
wrist.
(c) The superficial volar (ramus superficial volae), arising from the radial
artery, near the place where it leaves the front of the forearm, passes on-
wards into the hand. In size it is variable; in most instances it is very
small, and ends in the muscles of the thumb ; but in others it attains con-
siderable size, and crossing those muscles at their origins, terminates, as is
usually described, by inosculating with the radial extremity of the super-
ficial palmar arch, which it -thus completes.
398
RADIAL ARTERY.
Several unnamed muscular branches are given by the radial artery to the
muscles on the fore part of the arm.
B. The branches which arise from the radial artery behind the wrist are,
the posterior carpal, the metacarpal, the dorsal arteries of the thumb, and
the dorsal artery of the index finger.
(a) The posterior radial carpal is a small but constant branch. It arises
beneath the extensor tendons of the thumb, and running inwards on the
back of the carpus anastomoses with the posterior uluar carpal branch,
completing the arch from which spring the dorsal interosseous arteries of the
third and fourth spaces (p. 391). It anastomoses, also, with the terminal
branch of the anterior interosseous of the forearm.
(b) The first dorsal interosseous or metacarpal branch arises beneath the
extensor tendons of the thumb, frequently in common with the posterior
carpal branch, passes to the interval between the second and third
metacarpal bones, communicates with the corresponding perforating branch
of the deep palmar arch, and, descending on the second dorsal interosseous
muscle, anastomoses with the palmar digital branch at its division between
the fingers.
Fig. 279.
Fig. 279. DEEP VIEW OF THE ARTERIES OF THE
WRIST AND HAND, FROM BEFORE (from R.
Quain).
The anterior annular ligament of the carpus 1ms
been divided and the lower part of the common
flexors and flexor of the thumb has been re-
moved ; portions of these tendons are represented
as turned down upon the fingers with parts of the
lumbricales muscles; the superficial palmar artery
removed, and the interossei muscles are exposed.
a, ulnar nerve ; b, tendon of the flexor carpi
ulnaris muscle; c, tendon of the flexor carpi
radialis ; d, inserted tendon of the extensor ossis
metacarpi pollicis ; 1, radial artery ; 1', its lower
part before passing back within the extensor ten-
dons of the thumb, giving the anterior carpal and
superficial volar branches; 2, ulnar artery; 3,
anterior interosseous artery before passing behind
the pronator quadratus muscle ; 4, radial artery,
appearing deeply in the palm between the first and
second metacarpal bones and passing into the deep
palmar arch ; 5, deep branch of the ulnar artery
dipping between the abductor and flexor brevis
minimi digiti to join the deep arch and accom-
panied by the deep branch of the ulnar nerve ; 6,
a palmar digital artery, rising from the first part of
the superficial palmar arch ; 7, the princeps pol-
licis, and 8, the radialis indicia arteries rising from
the radial artery ; 9, 9, 9, interosseous branches
of the deep palmar arch proceeding down on the
interosseous muscles to join the palmar digital
arteries from the superficial arch.
(c) The dorsal arteries of the thumb, two
small branches, arising separately or together opposite the head of the meta-
carpal bone, run upon the dorsal aspect of the bones of the thumb, one at
the radial, the other at the ulnar border.
(d) The dorsal artery of the index finger, a very small branch, arises
DIGITAL BRANCHES. -PECULIARITIES. 399
lower down than the preceding, and, sending branches to the abductor
iudicis, runs along the radial side of the back of the index finger.
c. The branches derived from the radial after it has entered the hand,
are the great artery of the thumb, the radial branch of the index finger,
and its large terminal branch, which forms the deep palmar arch.
(a) The larye artery of the thumb (arteria princeps pollicis, Haller) arises
from the radial, where it is about to turn inwards across the palm of the
hand. It descends in front of the abductor iudicis, between the raetacarpal
bone of the thumb and the muscles covering it, to the space between the
lower ends of the dexor brevis pollicK At that point, and beneath the
tendon of the long flexor, it divides into two collateral branches, which
course along the borders of the phalanges, on the palmar aspect, and unite
in front of the last phalanx, to form an arch similar in arrangement to that
on the other fingers.
(6) The radial branch for the index finger generally arises close to the
large artery of the thumb ; but, though constantly found, it varies in size
and in its mode of origin. It descends between the abductor iudicis and
adductor pollicis muscles, and continues along the radial border of the index
finger, forming the racial collateral branch of that finger, and anastomosing
in the usual manner on the last phalanx with the ulnar collateral branch
derived from the superficial palmar arch.
This artery very frequently gives off a communicating branch to the superficial
arch, near the lower border of the adductor pollicis. But the most frequent com-
munication between the radial artery and the superficial arch is by means of the small
branch which proceeds from the former through the muscles of the thumb.
PECULIARITIES. Origin. In the observations of Richard Quain, the radial artery
was found to arise higher up than usual in nearly one case in eight.
Course.- The radial artery more rarely deviates from its usual position along the
fore arm than the ulnar. It has, however, been found lying upon the fibrous expan-
sion from the tendon of the biceps, and over the fascia of the fore -arm, instead of
beneath those structures. This vessel has been also observed on the surface of the
long supinator, instead of on the inner border of that muscle. In turning round the
wrist, it has been seen passing over the extensor tendons of the thumb, instead of
within them. But these several peculiarities are of very rare occurrence. As was
previously stated (p. 387), the vasa aberrantia occasionally derived from the bra-
chial or axillary arteries most commonly end by joining the radial, or one of its
branches.
Brandies. The radial recurrent is sometimes very large, or it may be replaced
by several separate branches. When the radial itself arUes high up, the recurrent
artery usually comes from the residual brachial trunk, or sometimes from the
ulnar artery, or more rarely from the interosseous. When given from the brachial
trunk, the radial recurrent has been found crossing beneath the tendon of the
biceps.
The superficial volar branch is small in a considerable number of cases, and is lost
in the short muscles of the thumb, without forming any connection with the palmar
arch, or with any of the digital arteries.
In some instances in which it is enlarged, it furnishes one or two digital branches,
and along with this the anastomosis with the superficial arch may be absent. The
superficial volar branch occasionally arises as much as an inch and a half higher than
usual.
The first dorsal interosseous branch (metacarpal), which descends on the second
interosseous space to the cleft between the index and middle fingers, is not unfre-
quently so large as to furnish the collateral digital branch to each of those fingers.
The carpal and interosseous (metacarpal) branches of the radial are sometimes
small, their place being supplied by the perforating offset of the anterior interosseous,
apparently by an enlargement of the ordinary anastomosis between them.
400
RADIAL AETEEY.
DEEP PALMAR ARCH.
The deep palmar arch, the continuation of the radial artery, commences
at the upper end of the first interosseous space between the heads of the
abductor indicis, turns transversely across [the palm towards the fourth
metacarpal bone, and inosculates with the communicating branch of the
ulnar artery. The convexity of the arch thus formed is directed downwards.
It rests on the interosseous muscles and on the metacarpal bones immediately
below their carpal extremities, and is covered by the flexor brevis pollicis,
the flexor tendons of the fingers, and the muscles of the little finger. It is
nearer to the carpus than the superficial
Fi S- 28 - arch, and differs from it in retaining its
size almost undiminished. It is in part
accompanied by the deep branch of the ulnar
nerve, which runs from the inner end of
the arch outwards.
BRANCHES :
(a) The recurrent branches (rami retrogradi,
Haller), from the upper concave side, ascend
and anastomose with the branches from the an-
terior carpal arch.
(b) The superior perforating branches, three
in number, pass backwards through the upper
extremities of the last three interosseous spaces
to inosculate with the dorsal interosseous ar-
teries.
(c) The palmar interosseous arteries, usually
three in number, but very liable to variation, lie
in front of the interosseous spaces, supply the
muscles there, and anastomose at the clefts of
the fingers with the digital branches from the
superficial arch.
It is by an enlargement of these small vessels
that the deep palmar arch sometimes supplies
the corresponding digital arteries in the absence
of those usually derived from the superficial
arch.
Fig. 280. DISSECTION OF THE LEFT ARM, SHOW-
ING AN ENLARGED MEDIAN ARTERY WHICH RE-
PLACES THE RADIAL AND ULNAR ARTERIES IN
THE SUPPLY OF PALMAR DIGITAL ARTERIES TO
HALF THE FINGERS (from Tiedemann).
1, lower part of the brachial artery; 2,
radial artery, not giving any superficial volar
branch ; 3, recurrent radial branch ; 4, ulnar
artery passing superficially over the wrist and
supplying at 4', digital arteries to half the hand ;
5, the enlarged median artery passing in front of
the annular ligament of the carpus, and sup-
plying 5', digital vessels to the outer half of the
hand.
VARIOUS CONDITIONS OF THE ARTERIES OF THE HAND.
The arteries of the hand frequently vary from their usual mode of distribution,
(a) By far the larger number of deviations consist of a deficiency in either the
THORACIC AOETA. 401
radial or the ulnar system of arteries, accompanied by a corresponding increase in the
other ; and it may be observed that the defect is much more commonly on the part
of the superficial, and the increase on the part of the deep set.
(b) In a second and smaller class of variations a deficiency in one or other of the
two systems is supplied, either by the enlargement of branches which descend in
front of the limb, as the superficial volar (from the radial), or the median artery
(from the anterior interosseous), or by the enlargement of a metacarpal branch (from
the radial) on the back of the hand.
In illustration of these general remarks, the following modes of arrangement of
the vessels may be mentioned.
In the greater number of cases the superficial palmar arch is diminished, and
gives off fewer digital branches than usual. Generally only one branch is wanting,
viz., that which supplies the adjacent sides of the fore and middle fingers ; but some-
times two or three branches are absent, or even all four, as when the ulnar artery,
after giving branches to the short muscles of the little finger, ends in the deep pal-
mar arch. In the last-mentioned case, which is rare 3 it is obvious that the superficial
arch is altogether wanting.
These various deficiencies in the superficial palmar arch and its branches are
usually compensated for by an enlargement of the deep arch, the palmar inter-
osseous branches of which, being increased in size, divide at the clefts of the fingers,
and form such collateral digital branches as are not derived from the usual source.
But a defective superficial arch may, as before mentioned, be reinforced from other
vessels, viz., from the superficial volar, from an enlarged median artery, or from a
large metacarpal branch.
It sometimes, but more rarely, happens, that the radial system of vessels is defi-
cient ; in which case the superficial arch (which belongs to the ulnar system) may
supply all the digital arteries to the thumb and fingers, or one of these may be derived
from the superficial volar, the median, or the radial interosseous artery.
DESCENDING AORTA. THORACIC AORTA.
From the point at which its arch i3 considered to terminate the lower
margin of the third dorsal vertebra, the aorta descends along the fore part
of the spine to the fourth lumbar vertebra, where it divides into the common
iliac arteries. The direction of this part of the vessel is not vertical, for, as
it follows the bend of the spine, upon which it rests, it is necessarily con-
cave forwards in the dorsal region, and convex forwards in the lumbar.
Again, as its commencement is at the left side of the bodies of the vertebrae,
and its termination also inclined a little to the left, whilst about the last
dorsal vertebra the vessel is nearly upon the median line, there is produced
another slight curve, the convexity of which is to the right side. Within
the thorax, where the offsets are small, the aorta diminishes only slightly in
size ; in the abdomen the diminution is considerable, in consequence of large
branches being furnished to the viscera of that cavity.
That part of the descending aorta which is situated in the thorax, is called
the thoracic aorta ; it extends from the lower border of the third dorsal
vertebra on the left side, to the opening between the crura of the diaphragm
in front of the last dorsal vertebra. It lies in the back part of the inter-
pleural space or mediastinum, being placed before the spine and behind the
root of the left lung and the pericardium ; on the left side it is in contact
with the corresponding pleura and lung, and close on the right side are the
azygos vein, the thoracic duct, and the oesophagus. The oesophagus, how-
ever, towards the lower part of the thorax is in front of the artery, and
near the diaphragm gets somewhat to the left side. The left or small azygos
vein crosses behind the thoracic aorta.
The branches derived from the thoracic aorta are numerous, but small.
402 THORACIC AORTA.
They are distributed to the walls of the thorax, and to the viscera con-
tained within it the latter being much the smaller and least numerous
branches.
A. The branches to the viscera are very irregular in their number and
place of origin. They are as follows.
The pericardiac branches are some very small and irregular vessels which
pass forwards and ramify on the pericardium.
THE BRONCHIAL ARTERIES are the proper nutritious arteries of the sub-
stance of the lung: they accompany the bronchial tubes in their ramifications
through that organ, and they also supply the bronchial glands, and in part
the oesophagus. These vessels vary frequently in number, and in their
mode of origin. The bronchial artery of the right side arises from the first
aortic intercostal artery, or by a common trunk with the left bronchial
artery from the thoracic aorta ; on the left side there are generally two
bronchial arteries, both of which arise from the thoracic aorta, one near the
commencement of that trunk, and the other, named inferior bronchial,
luwer down. Each artery is usually directed to the back part of the
corresponding bronchus, along which it run, dividing and subdividing with
the successive bronchial ramifications in the substance of the lung.
Peculiarities of the bronchial arteries. The place of origin is liable to much
variation. The artery of the right side has been found to arise singly from the aorta,
from the internal mammary, or from the inferior thyroid. The bronchial arteries of
the two sides have been seen to arise by a common trunk from the subclavian. (Haller.)
Two common trunks, each furnishing a branch to the right and left lungs, have been
observed in a single case to descend into the thorax after arising, one from the
internal mammary, and the other from the superior intercostal artery. (R. Quain,
pi. 26, f. 5.) Instances occur of two distinct bronchial arteries for each lung.
THE CEsofHAGEAL ARTERIES are variable in size and number. There are
usually four or five, which arise from the fore part or right side of the
aorta, and run obliquely downwards upon the oesophagus, supplying its
coats.
Their lower branches anastomose with the ascending offsets of the coronary artery
of the stomach, while their upper branches communicate with those of the inferior
thyroid artery.
Posterior mediastinal branches of the aorta, small and irregular, supply
the glands and loose tissue of the posterior mediastinum.
B. The branches furnished by the aorta to the walls of the thorax are
named intercostal from their distribution.
THE INTERCOSTAL ARTERIES arise from the posterior part of the aorta,
and run outwards upon the bodies of the vertebrae, to reach the intercostal
spaces. They are usually ten in number the upper intercostal space, and
occasionally also the second, being supplied by the superior intercostal
branch of the subclavian artery. Owing to the position of the aorta to the
left side of the spine, the right aortic intercostals cross over the front of
the vertebrae, furnishing small branches to their interior, and are longer
than the arteries of the left side. The vessels of both sides pass outwards
behind the pleura, and are crossed by the sympathetic nerve : those of the
right side also pass behind the oesophagus, the thoracic duct, and the azygos
vein.
In each intercostal space the artery, passing outwards more hori-
zontally than the ribs, crosses the space obliquely, so as to gain the
lower border of the upper rib near its angle. It lies upon the deep
surface of the external intercostal muscle, and in the back of the space
INTERCOSTAL ARTERIES.
403
is separated from the pleura by a fascia only, but further outwards it lies
between the two layers of intercostal muscles. Extending forwards in con-
Fig. 281. VIEW OF THE Fig. 281.
THORACIC AND UPPER
PART OF THE ABDOMINAL
AORTA, &c. 5
For the general descrip-
tion of this figure, see p. 334.
The following numbers in-
dicate the branches of the
aorta ; 1, placed between
the origins of the right and
left coronary arteries ; 2,
innominate ; 3, left carotid ;
4, left subclavian ; 5, bron-
chial ; 6, 6, cesophageal ; 7,
7, intercostal arteries (sixth
and seventh) ; 8, inferior
phrenic ; 9, cceliacaxis ; 10,
below the superior mesen-
tei ic and opposite the origin
of the renal arteries; il,
11, two of the lumbar
arteries.
tact with the rib above,
it finally anastomoses
with one of the anterior
intercostal branches de-
rived from the inter-
nal mammary artery,
and with the thoracic
branches of the axillary
artery.
The first of the aortic
intercostal arteries has
an anastomosis with the
superior intercostal pro-
ceeding from the sub-
clavian artery ; and the
last three are prolonged
into the abdominal mus-
cles, where they com-
municate with the epi-
gastric artery in front,
with the phrenic arteries
at the side, and with
the lumbar branches of
the abdominal aorta
lower down.
Each intercostal ar-
tery is accompanied, as
it runs outwards be-
tween the ribs, by a corresponding vein, and by one of the dorsal nerves >
the vein being usu illy uppermost, and the artery next below it.
404 THORACIC AND ABDOMINAL AORTA.
Branches. The named branches of the intercostal arteries are the
following.
(a) The posterior or dorsal branch of each intercostal artery passes back-
wards to the inner side of the anterior costo-transverse ligament, along with
the posterior branch of the corresponding spinal nerve ; and, having furnished
an offset to the spinal canal, reaches the muscles of the back, and divides
into an internal and an external branch. The internal branch is directed
towards the spinous processes, on or through the multifidus spinse, and
ramifies in the muscles and the skin. The external branch turns outwards
under the longissimus dorsi, and is distributed between that muscle and
the sacro-lumbalis ; some twigs reach the superficial muscles and the
integuments.
The spinal branches of the aortic intercostal arteries are distributed partly to the
cord and its membranes, and partly to the bones, in the same manner as the spinal
branches of the lumbar arteries, to the description of which tlie reader is referred.
(>) The collateral intercostal branch, long and slender, arises near the
place where the main trunk comes in contact with the upper rib of the
space, and inclining downwards approaches the border of the lower rib,
supplying the bone and the intercostal muscles, and anastomosing in front
with an anterior intercostal branch of the internal mammary artery. There
are thus in each intercostal space two terminal branches of the intercostal
arteries communicating with the branches of the internal mammary.
ABDOMINAL AORTA.
The aorta, after having passed the diaphragm, is thus named. It com-
mences on the front of the last dorsal vertebra, and terminates below by
dividing into two trunks, named the common iliac arteries. The bifurcation
usually takes place about half way down the body of the fourth lumbar
vertebra, a little to the left of the middle line ; a point which is nearly
on a level with a line drawn from the one crista ilii to the other, and
opposite the left side of the umbilicus.
The anterior surface of the abdominal aorta is successively in apposition
with the pancreas and the splenic vein, the left renal vein, the third portion
of the duodenum, and the peritoneum. The vena cava lies along its right
side, the right cms of the diaphragm being interposed at the upper part of
the abdomen ; close to the same side are the thoracic duct and the azygos
vein, which are placed between the aorta and the right crus of the dia-
phragm. The aorta is also covered in front by meshes of nerves derived
from the sympathetic, and numerous lymphatic vessels and glands.
Fig. 282. VIEW OP THE ABDOMINAL AORTA ["AND ITS PRINCIPAL BRANCHES (from
Tiedemann). 5
a, ensiform portion of the sternum ; J, vena cava inferior passing through the tendon
of the diaphragm ; c, the oesophagus passing through the muscular portion ; d, tendinous
part of the right, e, of the left crus ; /, /', the right and left kidneys with their supra-
renal bodies ; g, g', the ureters ; h, the upper part of the urinary bladder ; i, i, the right
and left vasa deferentia passing up from the bladder to the internal inguinal apertures ;
k t the rectum, divided and tied near its upper part ; 1, 1, the abdominal aorta ; 1', the
middle sacral artery ; 2, 2', the right, 3, 3', the left inferior phrenic arteries, represented
as arising by a short common stem from the front of the aorta immediately below the
meeting of the crura of the diaphragm ; 4, the trunk of tbe cceliac axis ; 5, the superior
mesenteric artery ; 6, 6, the renal arteries ; 6', 6', the suprarenal arteries arising partly
ABDOMINAL AORTA.
405
from the aorta and partly from the inferior phrenic ; 7, placed on the front of the aorta
below the origin of the spermatic arteries ; 7, 7', placed on the psoas muscles, point to
the right and left spermatic arteries as they descend to the internal inguinal apertures ;
8, inferior mesenteric artery ; 9, lumbar arteries, of which the lowest is here represented
as proceeding from the middle sacral artery ; 10, common iliac arteries ; 11, between
the external and internal iliac arteries ; 12, left epigastric artery ; 13, circumflex iliac;
1 i, branches of the ilio-lurnbar.
Fig. 28?.
408 ABDOMIXAL AORTA.
BRANCHES. The abdominal aorta gives numerous branches, which may
be divided into two sets, viz., those which supply the viscera, and those
which are distributed to the walls of the abdomen. The former consists of
the coeliac artery, the superior mesenteric, the inferior mesenteric, the cap-
sular, the renal, and the spermatic arteries ; whilst in the latter are included
the phrenic, the lumbar, and the middle sacral arteries. The first three of
the visceral branches are single arteries.
PECULIARITIES. Point of Division. In more than three-fourths of a considerable
number of cases, the aorta divided either upon the fourth lumbar vertebra, or upon
the intervertebral disc below it ; in one case of nine it was below, and in about one
of eleven above the spot thus indicated. In ten bodies out of every thirteen, the divi-
sion of the great artery took place within half an inch above or below the level of the
iliac crest; and it occurred more frequently below than above the fourth interver-
tebral space. (R. Quain, op. cit. p. 415.) An instance of bifurcation immediately
below the origin of the right renal artery is recorded by Haller (Disputat. Anatom.
t. vi. p. 781).
Unusual Branch. A. very remarkable case is recorded of the existence of a large
pulmonary branch which arose from the abdominal aorta, close to the coeliac artery,
and after passing upwards through the oesophageal opening in the diaphragm, divided
into two branches, which were distributed to the lungs near their bases. (Referred to
by R. Quain in his work " On the Arteries," p. 416.)
A. VISCERAL BRANCHES OF THE ABDOMINAL AORTA.
I. CCELIAC ARTERY OR AXIS.
The cceliac artery, a short arid wide vessel, arises from the aorta close
to the margin of the diaphragm. It is directed forwards nearly horizon-
tally, and is not more than half an inch long. It is behind the small
omentum, and lies close to the left side of the lobulus Spigelii of the liver,
and above the pancreas, the two semilunar ganglia being contiguous to it,
one on each side. This artery divides into three branches, viz.., the coro-
nary artery of the stomach, the hepatic and the splenic, which separate
simultaneously JFrom the end of the artery like radii from an axis.
PECULIARITIES. The coeliac axis is occasionally partly covered at its origin by the
diaphragm. It may be longer than usual, in which case its branches are not given
off together; or it may be entirely wanting, the coronary, hepatic, and splenic
arteries arising separately from the aorta. In some cases the coeliac artery gives off
only two branches at its division (the coronary and the splenic), the hepatic being
supplied from another source. ttarely, it gives more than three branches to the
viscera, the additional vessel being a second coronary, or a separate gastro-duodenal
artery. One or both phrenic arteries are sometimes derived from this trunk. Cases
have been met with in which a connection existed between the coeliac axis and the
superior mesenteric artery close to their origin.
Fig. 283. THE" ARTERIES OP THE STOMACH, LIVER, AND OMENTUM
(from Tiedemann). |
The liver is turned up so as to show its lower surface with the transverse fissure or
porta, and the vessels and ducts entering it. a, the right lobe of the liver; 6, the left
lobe; c, the gall-bladder; c', the biliary or hepatic ducts; c", the ductus coramunis
choledochns ; d, the front of the antero-posterior fissure and the round ligament ; e, the
cardiac orifice of the stomach ; f, on the great curvature of the stomach near its cardiac
end, points to the spleen ; </, the pylorus ; 7t, the duodenum ; i, the great omentum ; k,
some of the small intestines in the lower part of the abdomen ; 1, upon the trunk of the
abdominal aorta, below the root of the inferior phrenic arteries, and above the coeliac
axis ; 2, placed on the meeting of the crura of the diaphragm, the coronary artery of the
stomach ; 2', the same artery proceeding round the small curvature of the stomach and
ending by anastomosis with the superior pyloric ; 3, the main hepatic artery, continued
CCELIAC ARTERY AND BRANCHES.
407
at 3', as proper hepatic artery to the liver; 4, superior pyloric artery ; 4', another pjloric
branch ; 5, placed on the main trunk of the vena portee at the place where the hepatic
artery and ductus communis choledochus are in front of it ; 6', branches of the vena
portae in the transverse fissure ; 6, gastro- duodenal artery ; b", its continuation as the
right gastro- epiploic ; 7, on the left crus of the diaphragm, the splenic artery ; 8, its
left gastio-epiploic branch proceeding round the great curvature of the stomach to com-
municate with the right gastro-epiploic artery ; both of these vessels are seen giving long
epiploic as well as gastric branches.
Fig. 283.
1. THE CORONARY ARTERY OF THE STOMACH, the smallest of the throe
visceral branches derived from the cceliac artsry, inclining upwards and to
the left side, reaches the cardiac orifice of the stomach, and then proceed in"
along the smaller curvature of the stomach, from left to right, gives branches
to both sides of that viscus, and iuosculates with the pyluric branch of the
hepatic artery.
Where it first reaches the stomach, this artery sends upwards cesopliacjeal branches
which anastomose with the aortic oesophageal arteries. The branches to the stomach'
408 ABDOMINAL AORTA.
descending on the fore and back part of the organ, anastomose with branches from
the arterial arch on the great curvature.
The coronary artery of the stomach is sometimes given off directly from the aorta :
and is occasionally replaced by two separate vessels. It sometimes furnishes an
additional hepatic artery.
2. THE HEPATIC ARTERY is in the adult intermediate in size between the
coronary and splenic arteries, but, iu the foetus, it is the largest of the three.
The main part of this vessel inclines upwards and to the right side, be-
tween the layers of the small omentum, and in front of the foramen of
Winslow, towards the transverse fissure of the liver ; and in this course it
lies upon the vena portse and to the left of the bile-duct.
Near the transverse fissure of the liver, the hepatic artery divides into
right and left branches, which supply the corresponding lobes of that organ.
The left, the smaller division, lying in front of the vena portse, diverges at
an acute angle from the other branch, and turns outwards to reach the left
extremity of the transverse fissure of the liver, where it enters that organ.
The right hepatic artery inclines outwards to the right extremity of the
transverse fissure, and divides into two or three branches before entering
the liver. The ramifications of the hepatic artery in the liver accompany
the divisions of the vense portse and hepatic ducts.
BRANCHES, The named branches of the hepatic artery are as follow.
(a) The pyloric artery, coming in contact with the stomach at the upper
border of the pylorus, extends from, right to left along the smaller curvature
and inosculates with the coronary artery. It is sometimes a branch of the
gastro duodenal.
(b) The gastro- duodenal artery, of considerable size, separating from the
hepatic artery before that vessel ascends in the small omentum, descends
behind the duodenum, near the pylorus, and reaches the lower border of
the stomach ; there it gives off the pancreatico-duodenal branch, and its
remaining part, which receives the name of right gastro-epiploic, runs from
right to left along the great curvature of the stomach, between the layers of
the great omentum, and finally inosculates with the left gastro-epiploic
derived from the splenic artery.
The gastro-epiploic artery gives branches upwards to both surfaces of the stomach,
and long slender vessels downwards to the omentum.
The pancreatic duodenal branch descends along the inner margin of the duodenum,
between it and the pancreas, and, after furnishing several branches to both the-e
organs, anastomoses with a small offset of the superior mesenteric artery.
(c) The cystic artery, given off by the right hepatic when crossing behind
the cystic duct, turns upwards and forwards upon the neck of the gall-
bladder, and divides into two smaller branches, of which one ramifies
between the coats on the depending surface, the other between the bladder
and the liver.
PECULIARITIES. The hepatic artery sometimes arises from the superior mesenteric
artery, or from the aorta itself. Accessory hepatic arteries are often met with, usually
coming from the coronary artery of the stomach. The hepatic artery has been found
to furnish a phrenic branch.
3. THE SPLENIC ARTERY, in the adult the largest branch of the coeliac
artery, supplies the spleen, and in part the stomach and pancreas. It is
directed horizontally towards the left side. Waving and often tortuous in
its course, it passes, together with the splenic vein which is below it, behind
SPLEXIC ARTERY. 409
the upper border of the pancreas, and divides near the spleen into several
branches. The largest of these enter the fissure in that organ, and are dis-
tributed to its substance ; three or four are reflected towards the bulging
end of the stomach, upon which they ramify.
Fig. 234.
Fig. 284. THE ARTERIES OF THE STOMACH, DUODENUM, PANCREAS, AND SPLEEN
(from Tiedetnann). \
The stomach and liver are turned upwards so as to show their lower surface. The
jejunum is divided at its commencement, a, lower surface of the right lobe of the liver ;
b, left lobe ; c, cardiac oiifice of the stomach ; d, pylorus ; c, first part, /, second or
descending part, and g, third or lower part of the duodenum ; h, commencement of the
jejunum emerging from behind the superior mesenteric artery ; i, the head, and &, the
body of the pancreas; Z, the spleen ; 1, 1, right and left inferior phrenic arteries passing
from the aorta upon the crura of the diaphragm ; 2, placed on the aorta close to the
coeliac axis; 3, 3', the coronary artery; common hepatic; 4', proper hepatic artery ;
4", cystic branch ; 5, gastro- duodenal giving the inferior pyloric ; 5, on the great curva-
ture of the stomach, the right gastro-epiploic ; 6, pancreatico-duodenal ; 7, common
splenic ; 7', proper splenic ; 7", one of the vasa brevia to the stomach ; 8, 8, left gastro-
epiploic artery uniting with the right on the great curvature of the stomach ; 9, trunk of
the superior mesenteric artery, giving a small branch to join the pancreatico-duodenal ;
10, inferior mesenteric.
BRANCHES. (a) Pancreatic brandies, variable in size and number, are
given off whilst the artery is passing along the pancreas, the middle and
left part of which they supply with vessels. One of larger size not unfre-
quently runs from left to right in the direction of the pancreatic duct, and
is called pancreatica magna.
(6) The splenic branches are the proper terminal branches of the artery ;
they are five or six, or even more, in. number, and vary in length and size ;
they enter the spleen by the hilus or fissure in its concave surface, and
ramify within that organ.
(c) The short gastric branches (vasa brevia) vary from five to seven in num-
ber ; they are directed from left to right, some issuing from the trunk of the
splenic artery, others from its terminal branches : they reach the left ex-
tremity of the stomach, where they divide and spread out between the coats,
communicating with the coronary and left gastro-epiploic arteries.
E E
410 ABDOMINAL AORTA.
(d) The left yastro-epiploic artery runs from left to right along the great
curvature of the stomach, supplying branches to both surfaces of the
stomach and to the omentum on the left side, and inosculates with the
right gastro-epiploic branch from the hepatic artery.
II. SUPERIOR MESENTERIC ARTERY.
The superior mesenteric, an artery of large size, supplies the whole of the
small intestine beyond the duodenum, and half of the great intestine. It
arises from the fore part of the aorta, a little below the cosliac artery. For
a short space this artery is covered by the pancreas ; on emerging from
below that gland it descends in front of the duodenum near the end, and is
thence continued between the layers of the mesentery. The splenic vein
crosses over its root. In the mesentery the artery at first passes downwards
and to the left side, but afterwards turns towards the right iliac fossa,
opposite to which it inosculates with its own ileo-colic branch.
BRANCHES. (a) The inferior pancreaiico- duodenal, given off under cover
of the pancreas, runs along the concave border of the duodenum, and joins
with the pancreatico-duodenal artery.
(6) The rami intestini tennis, or intestinal branches, supplying the jejunum
and ileum, spring from the convex or left side of the vessel. They are
usually twelve or more in number, and are all included between the layers
of the mesentery. They run parallel to one another for some distance,
and then divide into two branches, each of which forms an arch with the
neighbouring branch. From the first set of arches other branches issue,
which divide and communicate in the same way, until finally, after forming
four or five such tiers of arches, each smaller than the other, the ultimate
divisions of the vessels proceed directly to the intestine, spreading upon
both sides, and ramifying in its coats.
(c) The colic branches arise from the right or concave side of the artery,
and are three in number.
1. The ileo-colic artery, the first in order from below upwards, inclines
downwards and to the right side, towards the ileo-colic valve, near which it
divides into two branches : one of these descends to inosculate with the
termination of the mesenteric artery itself, and to form an arch, from the
convexity of which branches proceed to supply the junction of the small
with the large intestine, and the csecum and its appendix ; the other divi-
sion ascends and inosculates with the next mentioned branch. The ileo-
colic artery is not always distinct from the termination of the superior
mesenteric.
2. The right colic artery passes transversely towards the right side,
beneath the peritoneum, to the middle of the ascending colon, opposite to
which it divides into two branches, of which one descends to communicate
with the ileo-colic artery, whilst the other ascends to join in an arch with
the middle colic. This artery and the ileo-colic often arise by a common
trunk.
3. The middle colic artery passes upwards between the layers of the
mesocolon towards the transverse colon, and divides in a manner exactly
similar to that of the vessels just noticed. One of its branches inclines to
the right, where it inosculates with the preceding vessel ; the other descends
to the left side, and maintains a similar communication with the left colic
branch, derived from the inferior mesenteric artery. From the arches of
inosculation thus formed, small branches pass to the colon for the supply of
its coats.
SUPERIOR MESENTERIC ARTERY. 411
Those branches of the superior mesenteric arter}^ which supply the ascend-
Fig. 285.
Fig. 285. THE SUPERIOR MESENTERIC ARTERY, AND ITS BRANCHES
(from Tiederuauu).
The transverse arch of the colon is turned upwards ; the transverse meso-colon is
dissected so as to expose the duodenum and pancreas at its root ; the small intestines are
thrown towards the left side; a, the descending part of the duodenum; b, the lower
part before it passes behind the superior mesenteric artery and root of the mesentery ; c,
the commencement of the jejunum to the left of the root of the mesentery ; c', </, the
jejunum and ileum ; d, the termination of the ileum in the caput csecum coli ; e, the
caecum ; /, the vermiform process ; g, the ascending colon ; h, the transverse arch ; i, the
descending colon ; k, the pancreas; 1, the trunk of the superior mesenteric artery; 1',
the termination of that vessel where it loops round into a branch of the ileo-colic ortery ;
2, 2, 2, 2, the intestinal branches ; 2', 2', 2', several of their loops in the mesentery ; 3,
small panereatico-duodenal branch passing to 3', to unite with the branch from the gastro-
duodenal ; 4, the middle colic branch ; 5, its left colic branch passing at 5' to unite with
the branch of the left colic of the inferior mesenteric ; 6, right branch ; 7, right colic and
ileo-colic arteries in one trunk ; 8, right colic, uniting by a loop with the middle colic ;
9, the ileo-colic, uniting with the end of the superior mesenteric artery.
E E 2
412 ABDOMINAL AORTA.
ing colon have a layer of peritoneum only on their anterior aspect : the
others lie between two strata.
The superior mesenteric artery is occasionally connected at its origin with the
cceliac artery. Not unfrequently it furnishes the hepatic artery.
III. INFERIOR MESENTERIC ARTERY.
This artery, much smaller than the superior mesenteric, supplies the lower
half of the colon, and the greater part of the rectum. It arises from the
aorta, between an inch and two inches above the bifurcation of that trunk.
The inferior mesenteric artery inclines to the left side in the direction of
the left iliac fossa, from which point it descends between the layers of the
mesorectum into the pelvis, and, under the name of " superior hsernor-
rhoidal " artery, runs down behind the rectum. It lies at first close to the
aorta, on its left side, and then crosses over the left common iliac artery.
BRANCHES. (a). The left colic artery is directed to the left side behind
the peritoneum, and across the left kidney to reach the descending colon.
Jt divides into two branches, and forms a series of arches in the same way
as the colic vessels of the opposite side. One of these two branches passes
upwards along the colon, and inosculates with the descending branch of
the middle colic ; whilst the other descends towards the sigmoid flexure,
and anastomoses with the sigmoid artery.
(6) The sigmoid artery runs obliquely downwards to the sigmoid flexure
of the colon, where it divides into branches ; some of which incline upwards
and form arches with the preceding vessel, while others turn downwards to
the rectum and anastomose with the following branch. Instead of a single
sigmoid artery, two or three branches are sometimes present.
(c) The superior hcemorrhoidal artery, the continuation of the inferior
mesenteric, passes^ into the pelvis behind the rectum, at first in the meso-
rectum, and then divides into two branches which extend one on each side
of the intestine towards the lower end. About five inches from the anus
these subdivide into branches, about a line in diameter, which pierce the
muscular coat two inches lower down, in the intestine, these arteries, about
seven in number, and placed at regular distances from each other, descend
between the mucous and muscular coats to the end of the gut, where they
communicate in loops opposite the internal sphincter, and end below by
anastomosing with the middle and inferior haemorrhoidal arteries.
ANASTOMOSES ON THE INTESTINAL TUBE. The arteries distributed to the
alimentary canal communicate freely with each other over the whole length
of that tube. The arteries of the great intestine derived from the two
mesenteric arteries, form a range of vascular arches along the colon and
rectum, at the lower end of which they anastomose with the middle and
inferior hsemorrhoidal arteries, given from the internal iliac and pudic
arteries. The branches from the left side of the superior mesenteric form
another series of arches along the small intestine, which is connected with
the former by the ileo-colic artery. Farther, a branch of the superior
mesenteric joins upon the duodenum with the pancreatico-duodenal artery.
The latter, at its commencement, is in a manner continuous with the pyloric
artery ; and so likewise, through the coronary artery of the stomach and
its ascending branches, a similar connection is formed with the cesophageal
arteries, even up to the pharynx.
INFERIOR MESEXTERIC ARTERY.
413
Fig. 286.
Fig. 286. THE INFERIOR MESENTERIC ARTKRY WITH ITS DISTRIBUTION AKD COMMUNICA-
TIONS (from Tiedemann). \
The small intestines with the superior mesenteric artery are turned towards the right
side, the pancreas is exposed, and the large intestine is sti'etched out : a, b, the duodenum ;
c, the commencement of the jejunum; d, the small intestine; e, the ascending colon ; f,
the transverse colon ; g, the descending colon ; h, the sigmoid flexure : i, the commence-
ment of the rectum ; &, the pancreas ; 1, placed on the trunk of the abdominal aorta at
the origin of the renal arteries ; 1', on the same at the origin of the inferior mesenteric ;
I' 1 , near the division into common iliac arteries ; 2, inferior mesenteric, giving off first the
left colic ; 3, ascending branch of the left colic ; 4, branches to the descending colon ; 5,
the sigmoid branch ; 6, the superior haemorrhoidal branch ; 7, the trunk of the superior
mesenteric issuing from behind the pancreas ; 8, some of its intestinal branches ; 9, the
middle colic artery ; 10, its left branch forming a loop of communication with the left
colic ; 11, its right branch; 12, the spermatic arteries.
IV. CAPSULAR OR SUPRARENAL ARTERIES.
The suprarenal or capsular arteries are two very small vessels which arise
from the aorta on a level with the superior mesenteriu artery, and incline
414 ABDOMINAL AORTA.
obliquely outwards upon the crura of the diaphragm to reach the supra-
renal capsules, to which bodies they are distributed, anastomosing at the
same time with the other capsular branches derived from the phrenic and
the renal arteries. In the foetus these arteries are of larger size.
V. RENAL OR BMULOENT ARTERIES.
The renal arteries, of large diameter in proportion to the size of the
organs which they supply, arise from the sides of the aorta, abjput half an
inch below the superior mesenteric artery, that of the right side being
rather lower down than that of the left. Each is directed outwards, so as
to form nearly a right angle with the aorta. In consequence of the position
of the aorta upon the spine, the right renal artery has to run a somewhat
longer course than the left, in order to reach the kidney. The artery
of the right side crosses behind the vena cava, and both right and left
arteries are overlapped by the accompanying renal veins. Previously to
reaching the concave border of the kidney, each artery divides into four or
five branches, the greater number of which usually lie intermediate between
the vein in front and the pelvis of the kidney behind. These branches,
after having passed deeply into the fissure of the kidney, subdivide and are
distributed in the gland, in the manner described in the account of the
structure of that organ.
BRANCHES. The renal artery furnishes a small branch to the suprarenal
capsule, a second to the ureter, and several others which ramify in the con-
nective tissue and fat behind the kidney.
PECULIARITIES. The renal artery may be replaced by two, three, four, or even five
branches ; and the greatest difference as to the origin of these vessels is found to exist
even on opposite sides of the same body. As they usually arise in succession from
the aorta itself, it would seem as if the deviation were merely a degree beyond that
in which the single artery divides into branches sooner than usual after its origin.
In some cases a renal artery has been seen to proceed from the common iliac ; and in
one case, described by Eustachius, from the internal iliac. Portal found in one
instance the right and left renal arteries arising by a common trunk from the fore
part of the aorta. In another case, one of several arteries arose from the front of the
aorta at its bifurcation ; or from the left common iliac at its origin.
The branches of the renal artery, instead of entering at the hilus, may reach and
penetrate the gland near its upper end, or on its anterior surface. Lastly, cases occur,
though very rarely, in which one of the renal arteries is wanting.
VI. SPERMATIC AND OVARIAN ARTERIES.
The spermatic arteries, two small and very long vessels, arise close toge-
ther from the fore part of the aorta a little below the renal arteries. Each
artery is directed downwards and outwards, resting on the psoas muscle ; it
crosses obliquely the ureter and, afterwards, the external iliac artery, and
turns forward to the internal abdominal ring. There it comes into contact
with the vas deferens, and, separating from the peritoneum, pa-ses with the
other constituents of the spermatic cord along the inguinal canal, and
descends to the scrotum, where it becomes tortuous, and reaching the back
part of the testis anastomoses with the artery of the vas deferens, and finally
divides into branches which pierce the fibrous capsule of the testis.
Fig. 287. VIEW OF THE ABDOMINAL AORTA AND ITS PRINCIPAL BRANCHES
(from Tiedernann).
For the detailed description of this figure see p. 404 ; 6, renal arteries ; 6', 6',
suprarenal arteries arising from the aorta ; other suprarenal arteries are seen proceeding
SPERMATIC AIS T D OVARIAN ARTERIES.
Fig. 287.
415
from the inferior phrenic ; 7, placed on the abdominal aorta below the origin of the spermatic
arteries; 7, 7', lower down the same arteries descending on the psoas muscles and cross-
ing the ureters, that on the left side entering the internal inguinal aperture along with
the vas deferens (i) ; 8, inferior mesenteric artery ; 9, lumbar arteries ; 9', the lowest
lumbar artery rising in this instance from the middle sacral (!') ; 10, 10', right and left
common iliac arteries; 11, 11, placed between the external and internal iliac arteries
on each side; 12, left epigastric artery ; 13, circumflex iliac artery.
416 ABDOMINAL AOHTA.
In the female, the ovarian arteries, corresponding to the spermatic arteries
in the male, are shorter than these vessels, and do not pass out of the abdo-
minal cavity. The origin, direction, aud connections of the ovarian artery
in the first part of its course are the same as in the male ; but at the
margin of the pelvis it inclines inwards, and running tortuously between
the layers of the broad ligament of the uterus, is guided to the attached
margin of the ovary, which it supplies wish branches. Some small offsets
can be also traced along the round ligament into the inguinal canal, and
others along the Fallopian tube : one, continuing inwards towards the
uterus, joins with the uterine artery.
In the young foetus the spermatic and ovarian arteries are short, as the testes and
the ovaries are at first placed close to the kidneys, but the arteries become lengthened
as these organs descend to their ultimate positions.
PECULIARITIES. The spermatic arteries occasionally arise by a common trunk.
Two spermatic arteries are not unfrequently met with on one side ; both of these
usually arise from the aorta, though sometimes one is a branch from the renal artery.
A case has occurred of three arteries on. one side, two from the aorta and the third
from the renal.
B. PARIETAL BRANCHES OF THE ABDOMINAL AORTA.
I. INFERIOR PHRENIC ARTERIES.
The phrenic arteries are two small vessels, which spring from the aorta
close together on a level with the under surface of the diaphragm. These
arteries are, however, somewhat irregular in their orgin. When they arise
separately from each other, which is by no means a constant arrangement,
one is frequently derived from the cceliac artery close to the origin, aud the
other from the aorta immediately above. They soon diverge from each
other, and, passing across the crura of the diaphragm, incline upwards aud
outwards upon its under surface ; the artery of the left side passing behind
the oesophagus, whilst that of the right side passes behind the vena cava.
Before reaching the central tendon of the diaphragm, each of the arteries
divides into two branches, of which one runs forwards towards the anterior
margin of the thorax, and anastomoses with the mu-sculo-phrenic branch of
the internal mammary artery, while the other pursues a transverse direction
towards the side of the thorax, and communicates with the terminations of
the intercostal arteries.
BRANCHES. Each phrenic artery gives small branches (superior capsular) to the
suprarenal capsule of its own side ; the left artery sends some branches to the
oesophagus, whilst the artery of the right side gives off small vessels which reach the
termination of the vena cava. Small offsets descend to the liver between the layers
of the peritoneum.
PECULIARITIES. The phrenic arteries are found to vary greatly in their mode of
origin, but these deviations seem to have little influence on their course and dis-
tribution. In the first place they may arise either separately, or by a common trunk :
and it would appear that the latter mode of origin is nearly as frequent as the
former.
When the two arteries are joined at their origin, the common trunk arises most
frequently from the aorta ; though, sometimes, it springs from the coeliac axis.
When arising separately, the phrenic arteries are given off sometimes from the*
aorta, more frequently from the coeliac axis, and occasionally from the renal ; but it
most commonly happens that the artery of the right side is derived from one, and
that of the left side from another of these sources. An additional phrenic artery
(derived from the left hepatic) has been met with.
.
LUMBAR ARTERIES. 417
In only one out of thirty-six cases observed by R. Quain did the phrenic arteries
arise in the mode ordinarily described; viz., as two separate vessels from the
abdominal aorta. (Op. cifc. p. 417.)
II. LUMBAR ARTERIES.
The lumbar arteries resemble the intercostal arteries, not only in their
mode of origin, but also in a great measure in the manner of their distribu-
tion. They arise from the back part of the aorta, and are usually four in
number on each side. Taey pass outwards, each resting on the body of the
corresponding lumbar vertebra, from the first to the fourth, and soon dip
deeply under the psoas muscle. The two upper arteries are likewise under
the pillars of the diaphragm ; and those on the right side are covered by the
vena cava. At the interval between the transverse processes, each lumbar
artery divides into a dorsal and an abdominal branch.
BRANCHES. (a) The abdominal branch of each lumbar artery runs outwards
behind the quadratus lumborum, the lowest of these branches not unfrequently in
front of that muscle. Continuing outwards between the abdominal muscles, the artery
ramifies in their substance, and maintains communications with branches of the
epigastric and internal mammary in front, with the terminal branches of the inter-
costals above, and with those of the ilio-lumbar and circumflex iliac arteries below.
(b) The dorsal branch of each lumbar artery, like the corresponding branch of the
intercostal arteries, gives off, immediately after its origin, an offset, named spinal,
which enters the spinal canal. The dorsal branch then, proceeding backwards with
the posterior primary branch of the corresponding lumbar nerve between the trans-
verse processes of the vertebrae, divides into smaller vessels, which are distributed to
the muscles and integuments of the back.
(c) The spinal branch enters the spinal canal through the intervertebral foramen,
and, having given an offset which runs along the nerves to the dura mater and cauda
equina, it communicates with the other spinal arteries, and divides into two branches,
which are distributed to the bones in the following manner : one curves upwards on
the back part of the body of the vertebra above, near to the root of the pedicle,
whilst the other descends in a similar manner on the vertebra below ; and each com-
municates with a corresponding branch from the neighbouring spinal artery. As
this arrangement prevails on both sides and throughout the whole length of the spine,
there is formed a double series of arterial arches behind the bodies of the vertebrae,
the convexities of which are turned towards each other. From the arches on opposite
sides offsets are directed inwards at intervals to reinforce a median longitudinal
vessel, which extends along the spine like the single artery on the front of the spinal
cord. The arches are moreover joined together across the bodies of the vertebrae by
transverse branches.
From this interlacement of vessels, numerous ramifications are distributed to the
periosteum and the bones.
PECULIARITIKS. The lumbar arteries of opposite sides, instead of taking their
origin separately from the aorta, occasionally commence by a common trunk, whose
branches pass out laterally, and continue their course in the ordinary way. Two
arteries of the same side are sometimes conjoined at their origin. On the last lumbar
vertebra, the place of a lumbar artery is often taken by a branch from the middle
sacral artery, and the ilio-lumbar compensates for the absence of the lumbar vessel
amongst the muscles.
MINUTE ANASTOMOSES OF THE VISCERAL AND PARIETAL BRANCHES OF
THE ABDOMINAL AORTA.
The existence of minute anastomoses between some of the visceral branches of the
abdominal aorta and those supplying the walls of the cavity has been recognised by
several anatomists, and various examples have been noticed in the previous descrip-
tion. These communications have recently been more distinctly proved and their
nature elucidated by W. Turner in a series of experimental injections, made with a
view to their detection. (" Brit, and For. Med. Chirug. Review," July, 1863.)
418 ABDOMINAL AOETA ILIAC AllTERIES.
These anastomoses constitute a well-marked vascular plexus, situated in the sub-
peritoneal tissue, whence Turner proposes to call them the subperitoneal arterial
plexus. It occupies the lumbar region from the diaphragm downwards into the iliac
regions and pelvis, and establishes communication between the parietal vessels and
those of the viscera, chiefly, though not exclusively, through branches of the arteries
of those viscera which are situated behind the peritoneum. It belongs to the renal
and suprarenal arteries, those of the pancreas and duodenum, the caecum, and the
ascending and descending parts of the colon. It extends also to the vessels of the
rectum, and to the spermatic arteries in their descent through the abdomen, and into
the inguinal canal and scrotum.
In these situations it was found that the injected material (coloured gelatine)
when thrown into the vessels of the viscus, so as to fill them completely, extended
through the subperitoneal plexus in various ways, so as to reach one or other set of
parietal vessels, such as the lumbar, ilio-lumbar, circumflex iliac, lower intercostal
and epigastric arteries ; and in the pelvis, the middle and lateral sacral arteries ; and
in the scrotum, the superficial pudic and perineal arteries.
The more direct inosculations of the hDcmorrhoidal arteries on the rectum with the
inferior hasmorrhoidal branches of the pubic artery are well known, and the importance
of these and other similar anastomoses, as well as the more extensive and minute
anastomosing plexus investigated by Turner, is obvious, with reference not merely to
the nutrition of the subperitoneal tissue, but also to the debated question of the
influence exerted by local superficial blood-letting on the state of the vessels of the
deeper viscera.
III. MIDDLE SACRAL ARTERY.
The middle sacral artery, the last of the branches of the abdominal aorta,
is a small vessel of about the size of a crowquill, which arises from the
extremity of the aorta just at the bifurcation. From this point the artery
proceeds downwards upon the last lumbar vertebra and over the middle of
the sacrum, as far as the coccyx, where it forms small arches of anastomosis
with the lateral sacral arteries.
BRANCHES. From its anterior surface some small branches come forward Avithin
the fold of the meso-rectum, and ramify upon the posterior surface of the intestine ;
and on each side others spread out upon the sacrum, and anastomose Avith the lateral
sacral arteries, occasionally sending small offsets into the anterior sacral foramina.
The middle sacral artery sometimes deviates a little to the side, and proceeds, not
from the bifurcation of the aorta, but from one of the common iliac arteries, usually
from that of the left side. This artery represents the caudal prolongation of the aorta
of animals.
COMMON ILIAC ARTERIES.
The common iliac arteries, commencing at the bifurcation of the aorta,
pass downwards and outwards, diverging from each other, and divide opposite
the lumbo-sacral articulation into the internal and external iliac arteries.
The common iliac arteries measure usually about two inches in length.
Both are covered by the peritoneum and the intestines, and are crossed by
thj ureters near their point of division, as well as by the branches of the
sympathetic nerve which are directed towards the hypogastric plexus.
They rest on the bodies of the vertebras, and come into contact with the
psoas muscles.
The common iliac artery of the right side is separated from the front of
the last lumbar vertebra, the two common iliac veins being interposed. The
artery of the left side is crossed by the branches of the inferior mesenteric
vessels.
Relation to Veins. The lefc iliac vein, supported on the last lumbar
COMMON ILIAC AllTERIES.
419
vertebra, lies to the inner side of, and below the left artery. On the right
side there are three veins in proximity to the artery ; the right iliac vein
lying behind the lower part of the vessel, the left iliac vein crossing behind
it, and the vena cava resulting from the union of the two others being on
the right side of the artery at the upper end.
PECULIARITIES. The place of origin of the common iliac arteries coincides with
that of the bifurcation of the aorta (p. 406).
Fig. 288. VIEW OP Fj g . 288.
THE RIGHT SIDE OP
A MALE PELVIS DIS-
SECTED TO SHOW
THE EXTERNAL AND
INTERNAL ILIAC AR-
TERIKS AND THEIR
BRANCHES. g
The viscera of the
pelvis have been re-
moved as well as the
internal iliac veins: the
larger nerves have been
retained, a, body of
the fifth lumbar ver-
tebra ; b, anterior and
superior spine of the
right ilium ; c, left
auricular surface of
the sacrum ; c', third
piece of the sacrum ;
d, first piece of the
coccyx ; e, short sacro-
sciatic ligament ; f,
tuberosity of the is-
chium covered inter-
nally by the great
sacro- sciatic ligament ;
f/, obturator foramen ;
ij iliacus muscle ; 1,
lower part of the ab-
dominal aorta ; 1',
middle sacral artery ;
2, 2, common iliac ar-
teries ; 2', right exter-
nal iliac ; 3, lower
part of the vena cava
inferior ; 4, 4, common iliac veins ; the number on the right points by a line to the right
internal iliac artery ; 4', right external iliac vein ; 5, placed on the ilio-lumbar nervous
trunk, points to the posterior division of the internal iliac artery giving off the gluteal ;
5', ilio-lumbar artery ; 5", lateral sacral artery with branches passing into tbe anterior
sacral foramina : 6, placed on the anterior division of the first sacral nerve, points to the
sciatic artery coming from the anterior division of the internal iliac ; 7, pudic artery; 7',
the same artery passing behind the spine of the ischium, and proceeding within the
ischium and obturator interims muscle, accompanied by the pudic nerve towards the
perineum ; towards f, inferior huemorrhoidal branches are given off; 7", superficial
perineal artery and nerve ; 8, hypogastric artery, with the obliterated remains of the
umbilical artery cut short, and 8', superior vesical branches rising from it ; 9, obturator
artery with the corresponding nerve and vein ; 9', the pubic twigs which anastomose
with descending twigs of the epigastric artery, and from which, by the enlargement of
one of them, the aberrant obturator artery may proceed ; 10, inferior vesical ; 11, middle
hffimorrhoidal vessels rising in this instance from the pudic ; 12, epigastric artery winding
to the inside of +, +, the vas deferens and spermatic cord ; 13, circumflex iliac artery ;
14, spermatic artery and vein divided superiorly ; 15, twigs of the ilio-lumbar artery
proceeding to anastomose with the circumflex iliac.
420 INTERNAL ILIAC ARTERY.
The place of division of these arteries is subject to great variety. In two thirds of
a large number of cases, it ranged between the middle of the last lumbar vertebra and
the upper margin of the sacrum ; in one case out of eight it was above, and in one
case out of six it was below that space. Most frequently the left artery was found to
divide lower down than the right. (R. Quain.)
The length varies in most instances between an inch and a half and three inches,
but it has been seen in some rare cases less than half an inch, and as long as four
inches and a half. In one instance recorded by Cruveilhier, (" Anat. descript." v. iii.
p. 186,) the right common iliac artery was wanting, and the internal and external
vessels of that side arose as distinct branches from the aorta.
Branches. The common iliac artery often gives off a small unnamed branch to the
lymphatic glands, the ureter or the psoas muscle, and sometimes even a larger branch
a renal artery, a lumbar, or the ilio-lumbar.
INTERNAL ILIAC ARTERY.
The internal iliac artery (hypogastrica, pelvica) extends from the bifurca-
tion of the common iliac artery towards the sacro-sciatic foramen, near
which, it divides into branches. It is usually about an inch and a half in
length, and is smaller than the external iliac in the adult, but the reverse in
the foetus. At its origin, the artery lies near the inner border of the psoas
muscle ; lower down, it rests against part of the pyriform muscle. Behind
it are situated the internal iliac vein, and the communicating branch which
passes from the lumbar to the sacral plexus of nerves : in front it is crossed
by the ureter, which separates it from the peritoneum.
BRANCHES. The branches of the internal iliac artery, though constant,
and regular in their general distribution, vary much in their origin. They
arise, in most instances, from two principal divisions of the parent trunk,
of which one is anterior to the other. From the anterior division arise the
superior vesical (connected with the pervious portion of the foetal hypo-
gastric artery), the inferior vesical, middle haemorrhoidal, obturator, internal
pudic, and sciatic arteries, and also, in the female, the uterine and the
vaginal arteries. The posterior division gives off the gluteal, the ilio-lumbar,
and the lateral sacral arteries.
PECULIARITIES. Length. The internal iliac artery has been found as short as
half an inch, and sometimes as long as three inches, but it is not often less than an
inch in length. An instance has been observed in which this vessel was absent, and its
branches were derived from a bend of the external iliac artery down into the pelvis
(Preparation in Univ. Coll. Mus., London). The lengths of the common iliac and
internal iliac arteries bear an inverse proportion to each other the internal iliac
being long when the common iliac is short, and vice versa. Moreover, when the
common iliac is short, the internal iliac (arising higher than usual) is placed for some
distance above the brim of the pelvis, and descends by the side of the external iliac
to reach that cavity.
The place of division of the internal iliac into its branches varies between the upper
margin of the sacrum and the upper border of the sacro-sciatic foramen.
Branches. Sometimes all the branches of the internal iliac artery arise without the
previous separation of that vessel into two portions.
In more than a fourth of R. Quain's cases a branch, corresponding usually to the
ilio-lumbar artery, arose before the subdivision of the main trunk.
HYPOGASTRIC ARTERY. In the foetus, the internal iliac artery, retaining
almost the full size of the common iliac, curves forwards from that artery
to the side of the urinary bladder, and ascends on the anterior wall of the
abdomen to the umbilicus. There the vessels of opposite sides come into
YESICAL ARTERIES. 421
contact with one another and with the umbilical vein, and, coiling spirally
round that vein in the umbilical cord, they proceed to the placenta. To
that part of the artery which is placed within the abdomen, the term hypo-
gastric is applied ; the remaining portion, passing onwards through the
umbilicus to the placenta, being the proper umbilical artery. After the
cessation of the placental circulation at birth, the two hypogastric arteries
become impervious from the side of the bladder upwards to the umbilicus,
and are converted into fibrous cords. These two cords, which extend
from the sides of the bladder to behind the umbilicus, being shorter than
the part of the peritoneum on which they rest, cause a fold of the serous
membrane to project inwards ; and thus are formed two fossae (fossae of the
peritoneum) on each side of the abdomen, in one or other of which the pro-
jection of a direct inguinal hernia takes place. The part of the artery
intervening between the origin of the vessel and the side of the bladder
remains pervious, although proportionally much reduced in size, and forms
the trunk of the superior vesical artery.
BRANCHES OF THE INTERNAL ILIAC ARTERY/.
I. VESICAL ARTERIES.
The urinary bladder receives several arteries, amongst which, however,
may be specially recognised two principal branches, a superior and an inferior
vesical artery.
The superior vesical artery is, at its commencement, that part of the
hypogastric artery in the fcetus which remains pervious after the changes
that take place subsequently to birth. It extends from the anterior di-
vision of the internal iliac to the side of the bladder.
BRANCHES. (a) It distributes numerous branches to the upper part and sides of
the bladder.
(6) The artery of the vas deferens, or the deferent artery, arising from one of the
lowest of these, is a slender artery which reaches the vas deferens, and accompanies
that duct in its course through the spermatic cord to the back of the testicle, where it
anastomoses with the spermatic artery.
(c) Other small branches ramify on the lower end of the ureter.
The inferior vesical artery (vesico-prostatic), derived usually from the
anterior division of the internal iliac, is directed downwards to the lower
part of the bladder, where it ends in branches which are distributed to the
base of the bladder, to the side of the prostate, and to the vesiculse semi-
nales. One offset, to be presently described, descends upon the rectum.
The branches upon the prostate communicate more or less freely upon that body
with the corresponding vessels of the opposite side, and, according to Haller, with
the perineal arteries likeAvise.
Small twigs of this vessel also run towards the subpubic arch, and in instances of
deficient pudic arteries replace one or more of their branches, as will be more fully
noticed under those arteries.
Besides the superior and inferior vesical arteries, other smaller branches will be
found to reach the bladder, and usually one slender vessel which is distributed parti-
cularly to the under surface of the vesiculae seminales.
Middle hcemorrhoidal artery. This branch is usually supplied to the
rectum by the inferior vesical artery, but sometimes proceeds from other
422
INTERNAL ILIAC ARTERY.
Fig. 289.
Fig. 289. VIEW OP THE VISCERA OF THE MALE PELVIS FROM THE LEFT SIDE, SHOWING
THE VESIOAL AND PDDIC ARTERIES (from R. Quain).
a, the os pubis divided a little to the left of the symphysis ; J, placed close to the
upper part of the urinary bladder, upon which lies the vas defei'ens ; c, placed on the
upper part of the rectum, near the left ureter ; c', at the junction of the middle and lower
parts of the rectum points to the vesicula seminalis ; c", the anus ; d, the urethral bulb ;
c, the crus penis divided ; /, the short sacro-sciatic ligament attached to the spine of the
iscbium ; 1, common iliac artery ; 2, internal iliac artery ; 3, gluteal artery cut short ;
4, common trunk of the sciatic and pudic arteries ; 4', sciatic artery cut as it is passing
out of the great sacro-sciatic foramen ; 5, placed on the divided surface of the ischium
near the spine, points to the pudic artery as it is about to re-enter the pelvis by the
lesser sacro-sciatic foramen 5', the superficial perineal branches of the pudic ; 5", the
pudic artery, proceeding to give the artery of the bulb, and passing on to give 6, the
artery of the crus penis and the dorsal artery of the penis ; 7, placed on the middle part
of the rectum, points to the descending branches of the superior hsemorrhoidal artery ; 8,
the superior and middle vesical arteries ; 9, the inferior vesical artery, of considerable
size in this instance, giving branches to the bladder, the vesicula seminalis, the rectum
(middle hajmorrhoidal), and 9', to the prostate gland.
sources,
arteries.
It anastomoses with, the branches of the other hremorrhoidal
II. UTERINE AND VAGINAL ARTERIES.
The uterine artery is directed downwards from the anterior division of the
internal iliac artery towards the neck of the utsrus. Insinuating itself be-
tween the layers of the broad ligament, it passes upwards on the side of the
uterus, pursuing an exceedingly tortuous course, and sends off numerous
branches, which enter the substance of that organ.
This artery supplies small branches to the bladder and the ureter ; and, near its
termination, communicates with an offset directed inwards from the ovarian artery.
Vaginal artery. The vagina derives its arteries principally from a branch
which corresponds with the inferior vesical in the male. The vaginal artery
descends and ramifies upon the vagina, at the same time sending some
OBTURATOR ARTERY. 423
offsets to the lower parb of the bladder over the neck, and others to the
contiguous part of the rectum.
Fig. 290.
Fig. 290. VIEW OF THE DISTRIBUTION OF THE ARTERIES TO THE VISCERA OF THE FEMALE
PELVIS, AS SEEN ON THE REMOVAL OF THE LEFP Os INNOMINATU5I, &C. (from R.
Quaiii). i
a, the left auricular surface of the sacrum ; J, the spine of the ischium with the short
sacro-sciatic ligament ; c, the os pubis cut a little to the left of the symphysis ; d, placet!
upon the sigmoid part of the colon, and d' on the lower part of the urinary bladder, point
to the ureter ; e , on the upper part of the body of the uterus, points by a line to the left
ovary ; f, on the upper part of the bladder, points to the left Fallopian tube ; f, round
ligament of the uterus ; 1, left external iliac artery cut short ; 2, left internal iliac
artery ; 3, gluteal artery cut short ; 4, 4, left pudic artery from which a part has been
removed; 4', the same artery after it has re-entered the pelvis proceeding towards the
muscles of the perineum, clitoris, &c. ; 5, placed on the sacral nerves, points to the sciatic
artery ; 6, 6', inferior vesical and vaginal arteries ; 6", branches from these to the rectum ;
7, uterine artery much coiled ; 8, the superior vesical, and 8', the remains of the hypo-
gastric artery ; 9, 9, the left ovarian artery, descending from the aorta, and emerging
from below the peritoneum ; 10, the superior hsemorrhoidal artery spreading over the left
side of the rectum.
III. OBTURATOR, ARTERY.
The obturator artery is in most instances derive! from the internal iliac ;
it usually arises from the anterior portion of that vessel, but not unfre-
quently from its posterior division. The artery is directed forwards along
the inside of the pelvis to reach the groove at the upper part of the thyroid
foramen. By this aperture it passes out of the pelvis, and immediately
divides into its terminal branches. In its course through the pelvis, the
artery is placed between the pelvic fascia and the peritoneum, a little below
the obturator nerve. Beneath the pubes it lies with its accompanying vein
and nerve in an oblique canal, formed partly by a groove in the bone, and
partly by fibrous tissue, after passing through which it divides immediately
424
INTERNAL ILIAC ARTERY.
into an external and an internal branch, which are deeply placed behind the
external obturator muscle.
BRANCHES. (a) Within the pelvis, besides others of smaller size, the obturator
artery often supplies a branch to the iliac fossa and muscle, and one which run.s
backwards upon the urinary bladder.
(b) Anastomotic vessels, which may be called pubic, are given off by the obturator
artery as it is about to escape from the pelvis : these vessels ramify on the back of the
pubes, and communicate behind the bone and the attachments of the abdominal
muscles, with small offsets from the epigastric artery. These anastomosing branches
lie to the inner side of the crural ring.
(c) The internal terminal branch curves inwards beneath the obturator externus,
close to the inner margin of the thyroid foramen, and furnishes branches to the obtu-
rator muscles, the gracilis, and the adductor muscles.
(d) The external terminal branch has a similar arrangement near the outer margin
of the thyroid foramen ; it descends as far as the ischial tuberosity, and supplies the
obturator muscles, and the upper ends of the long muscles which are attached to that
tuberosity. This branch usually sends off a small artery, which enters the hip-joint
through the cotyloid notch, and ramifies in the synovial fatty tissue, and along the
round ligament as far as the head of the femur.
Fig. 291.
Fig. 291. A. and B. VIEWS
OF THE LEFT WALL OF THM
PELVIS, WITH THE ATTACHED
ABDOMINAL MUSCLES FROM
THE INSIDE, SHOWING DIF-
FERENT POSITIONS OF THE
ABERRANT OBTURATOR AR-
TERIES (from R. Quaiti).
In A, a case is represented
in which the aberrant artery
passes to the outside of a
femoral hernial protrusion ; in
B, an instance is shown in
which it surrounds the neck of
the sac.
a, posterior surface of the
rectus muscle ; b, iliacus in-
ternus muscle ; c, symphysis
pubis ; d, obturator mem-
brane ; e, placed on the fascia
transversalis, points to the vas
deferens passing through the
internal inguinal aperture ; f,
the testicle ; + , the neck of a
femoral hernial sac ; 1, the
external iliac artery ; 2, the
external iliac vein ; below 2,
the obturator nerve; 3, the
epigastric artery; 4, aberrant
obturator artery, arising from
the epigastric.
The two terminal branches
of the obturator artery com-
municate with each other near
the lower margin of the ob-
turator ligament, and anastomose with branches of the internal circumflex artery.
The external branch also communicates with offsets from the sciatic artery near the
tuber ischii.
PECULIARITIES. The obturator artery frequently has its origin transferred to the
'PUDIC ARTERY. 425
commencement of the epigastric artery, and sometimes to the external iliac at its
termination.
In 361 cases observed by R. Quain, the origin of the obturator artery varied as
follows. In the proportion of 2 cases out of 3, it arose from the internal iliac^'in 1
case out of 3^, from the epigastric : in a very small number of cases (about 1 in 72),
it arose by t\vo roots from both the above-named vessels; and in about the same
proportion, from the external iliac artery.
Sometimes the obturator artery arises from the epigastric on both sides of the same
body, but in the majority of instances, this mode of origin of the vessel is met with
only on one side.
When the obturator artery arises from the epigastric, it turns backwards into the
pelvis to reach the canal at the upper part of the thyroid foramen ; and in this course
it is necessarily close to the crural ring, the opening situated at the inner side of the
external iliac vein, through which hernial protrusions descend from the abdomen into
the thigh. In the greater number of instances the artery springs from near the root
of the epigastric, and is directed backwards close to the iliac vein, and therefore lies
to the outer side of the femoral ring ; but in other instances, arising from the epigastric
artery higher up, it occasionally,crosses over the ring, and curves to its inner side. It
is when it takes this last course that the obturator artery is liable to be wounded in
the operation for dividing the stricture in a femoral hernia.
The anastomosis which normally exists between the obturator artery and the
epigastric explains the nature of the change which takes place when the origin of the
obturator artery is transferred from the one place to the other. In such cases one of
the anastomosing vessels may be supposed to have become enlarged, and the posterior
or proper root of the obturator artery to have remained undeveloped or to have been
obliterated in a proportionate degree.
IV. PUDIC ARTERY.
The pudic or internal puJic artery is a branch of considerable size (smaller
in the female than in the male), which is distributed to the external gene-
rative organs. The following description of this artery has reference to its
arrangement in the male ; its distribution in the female will be noticed
separately.
The pudic artery arises from the anterior division of the internal iliac,
sometimes by a trunk common to it and the sciatic artery. Proceeding
downwards, it passes superficially or posteriorly close to the ischial spiue, thus
emerging from the pelvis along with the sciatic artery, through the great
sacro-sciatic foramen. Continuing iu a uniformly curved course, it re-enters
the pelvis by the small sacro-sciatic foramen, immediately below the ischial
spiue, and passes forward on the inner side of the tuber ischii, in the sub-
stance of the obturator fascia.
Distant at first from the lower margin of the ischial tuberosity an inch
or an inch and a half, it approaches the surface of the inner margin of the
pubic arch, and lies subjacent to the triangular ligament or superficial layer
of the subpubic fascia. Finally, piercing this fascia, it divides below the
subpubic arch into the dorsal artery of the penis and the artery of the
corpus caver nosum.
In the first part of its course, whilst within the pelvis, the pudic artery
lies to the outer side of the rectum, and in front of the pyriformis muscle
and the sacral nerves. Thence onwards it is accompanied by the pudic
nerve and vein. On the ischial spine it is covered by the glutens maximus
muscle close to its origin. In the obturator fascia it lies externally to the
ischio-rectal fossa and internally to the obturator internus muscle, and
beneath the triangular ligament it is crossed by the deep transverse perineal
muscle.
F F
426
INTERNAL ILIAC ARTERY.
BRANCHES. (a) The inferior or external hcemorrhoidal arteries, two or three in
number, incline inwards from the pudic artery as it passes outside the ischio-rectal
fossa above the tuber ischii. These small vessels run across the ischio-rectal fossa,
through the fat in that space, and are distributed to the sphincter and levator ani
muscles, and to the parts surrounding the anus.
Fig. 292.
Fig. 292. VIEW OF THE DISTRIBUTION OP THE ARTERIES TO THE VISCERA OP THE MALE
PELVIS, AS SEEN ON THE REMOVAL OF THE LEFT Os INNOMINATUM, &C. (from R. Qliain).
a, left external oblique muscle of the abdomen divided ; b, internal oblique ; c, trans-
versalis; d, d, the parts of the rectus muscle divided and separated; c. psoas magnus
muscle divided ; f, placed on the left auricular surface of the sacrum, points by a line to
the sacral plexus of nerves ; g, placed on the os pubis, sawn through a little to the left of
the symphysis, points to the divided spermatic cord ; h, the cut root of the crus penis ;
*, the bulb of the urethra ; fc, elliptical sphincter ani muscle ; Z, a portion of the ischium
near the spinous process, to which is attached the short sacro-sciatic ligament ; m, the
parietal peritoneum; n, the upper part of the urinary bladder; n', n', the left vas deferens
descending towards the vesicula seminalis ; n", the left urettr ; o, the intestines ; ], the
common iliac at the place of its division into external and internal iliac arteries ; 2, left
external iliac artery ; 3, internal iliac ; 4, obliterated hypogastric artery, over which the
vas deferens is seen passing, with the superior vesical artery below it ; 5, middle vesical
artery ; 6, inferior vesical artery, giving branches to the bladder, and descending on the
prostate gland and to the back of the pubes ; 7, placed on the sacral plexus, points to the
common trunk of the pudic and sciatic arteries ; close above 7, the gluteal artery is seen
cut short ; 8, sciatic artery cut short as it is escaping from the pelvis; 9, placed on the
rectum, points to the pudic artery as it is about to pass behind the spine of the ischium ;
9', on the lower part of the rectum, points to the inferior hasmorrhoidal branches ; 9",
on the perinaeum, indicates the superficial perineal branches ; 9'", placed on the prostate
gland, marks the pudic artery as it gives off the arteries of the bulb and of the crus penis ;
10, placed on the middle part of the rectum, indicates the superior hsemorrhoidal arteries
as they descend upon that viscus.
(&) The superficial perineal artery, a long, slender, but regular vessel, supplies the
scrotum and the upper part of the perinaeum. Given off from the pudic artery in
front of the haemorrhoidal branches, it turns upwards parallel with the pubic arch,
crosses the transverse muscle of the perinseum, and runs forwards under cover of the
BRANCHES OF THE PUDIC ARTERY.
427
superficial fascia, between the erector penis and accelerator urinae muscles, supplying
both. In this course the artery gradually becomes superficial, and is finally distri-
buted to the skin of the scrotum and the dartos. It not unfrequently gives off the
following branch.
Fig. 293. DISSECTION Fig. 293.
OF THE PERINJEUM IN A
YOUNG MALE SUBJECT,
SHOWING THE BLOOD-
VESSELS, &C. 4
This drawing is made
from a preparation upon
a modification of the plan
of R. Quain's 61st and
62nd Plates. The right
side shows a superficial,
the left a deeper view.
a, the anus, with a
part of the integument
surrounding it ; b, left
half of the bulb of the
urethra exposed by the
removal of a part of the
bulbo-cavernosus muscle ;
c, coccyx ; d, right tube-
ro&ity of the ischium ; e,
e, the anterior part of the
superficial perineal fascia
passing forward upon the
scrotum, and removed
from the surface of the
muscles and its reflections
into the deep fascia ; /",
right ischio -rectal fossa,
from which the fat and
fascia have not been re-
moved ; g, glutens ruaxi-
mus muscle ; 1, placed
on the right transversus
perinsei muscle, points to
the superficial perineal
artery as it emerges in
front (in this case) of the
muscle; 1', placed on the
left side on the surface of
the triangular ligament
near its reflection into
the superficial fascia, points to the superficial perineal artery cut short ; 2, on the right
ischio -cavernosus muscle, points to the superficial perinea! arteries and nerves passing
forward ; 2', the same on the left side, the vessels and nerves having been divided there ;
3, on the triangular ligament of the right side, points to the transverse perineal branch
of the superficial perineal artery ; 4, on the left tuberosity of the ischium, points to the
pudic artery deep in the ischio-rectal fossa ; 5, 5', the inferior haamorrhoidal branches
of the pudic arteries and nerves ; 6, on the left side, placed in a recess from which the
triangular ligament or anterior layer of the subpubic fascia has been removed to show the
continuation of the pudic artery, its branch to the bulb, and one of Cowper's glands.
(c) The transverse perineal artery, a very small vessel, arises either from the
pudic artery, or from the superficial perineal, near the transversus perinasi muscle.
It lies across the perineeum, and terminates in small branches which are distributed
to the transverse muscle, and to the parts between the anus and the bulb of the
urethra.
(d) The artery of the bulb, is, surgically considered, an important vessel. It is very
F F 2
428 INTERNAL ILIAC' ARTERY.
short ; arising from the pudic between the layers of the subpubic fascia, and passing
transversely inwards, this artery reaches the bulb a little in front of the central
point of the perineum, and ramifies in the erectile tissue. It gives a branch to
Cowper's gland.
(e) The artery of the corpus cavernosum (profunda penis), one of the terminal
branches of the internal pudic, runs a short distance between the crus penis and the
ramus of the pubes, and then continuing forward, penetrates the crus, and ramifies
in the corpus cavernosum.
(/) The dorsal artery of the penis runs between the crus and the pubic symphysis :
having pierced the suspensory ligament, it continues along the dorsum of the penis
immediately beneath the skin, and parallel with the dorsal vein, as well as with the
corresponding artery of the opposite side. It supplies the integument of the penis,
and the fibrous sheath of the corpus cavernosum, anastomosing with the deep arteries ;
and, near the corona glandis, divides into branches, which supply the glans and the
prepuce.
PECULIARITIES. Origin. The pudic artery is sometimes small, or it is defective in
one or two, or even three of its usual branches, which, in those circumstances, are sup-
plied by a supplemental vessel, the " accessory pudic" The defect most frequently
met with is that in which the pudic ends as the artery of the bulb, whilst the arteries
of the corpus cavernosum and the dorsum of the penis are derived from the acces-
sory pudic. But all the three arteries of the penis may be supplied by the accessory
pudic, the pudic itself ending as the superficial permeal. A single accessory pudic
has been seen to supply both cavernous arteries, whilst the pudic of the right side
gave both dorsal arteries. On the other hand, cases have occurred in which only
a single branch was furnished by the accessory artery, either to take the place of
an ordinary branch altogether wanting, or to aid one of the branches which was
diminutive in size.
The accessory pudic, the occasional artery above alluded to, generally arises from
the pudic itself, before the passage of that vessel from the sacro-sciatic foramen, and
descends within the pelvis, and along the lower part of the urinary bladder. It lies
on the upper part of the prostate gland, or it may be, for a short space, likewise on
the posterior margin, and then proceeding forwards above the membranous part of
the urethra, reaches the perinaeum, by piercing the fascia of the subpubic arch.
The accessory pudic sometimes arises with the other branches from the internal
iliac, and is not unfrequently connected with the prostatic or other branch of the
inferior vesical artery. A vessel having a similar distribution may spring from the
external iliac, through an irregular obturator, or through the epigastric artery.
Branches. Artery of the bulb. This vessel is sometimes small, sometimes
wanting on one side, and occasionally it is double. But a more important deviation
from the common condition is one sometimes met with, in which the vessel, arising
earlier, and crossing the perineum farther back than usual, reaches the bulb from
behind. In such a case there is considerable risk of dividing the artery in performing
the lateral operation for stone. On the other hand, when this small vessel arises
from an accessory pudic artery, it lies more forward than usual, and out of danger in
case of operation.
The dorsal artery of the penis has been observed to arise from the deep femoral
artery and to pass obliquely upwards and inwards to reach the root of the penis.
Tiedemann gives a drawing of this variety.
The pudic artery in the female. In the female this vessel is much
smaller than in the male. Its course is similar, and it gives the following
branches.
The superficial perineal branch is distributed to the labia pudendi. The
artery of the bulb supplies the mass of erectile tissue above and at the
sides of the entrance of the vagina, named the bulb of the vagina. The
two terminal branches, corresponding to the artery of the corpus cavernosum
and the dorsal artery of the penis, are distributed to the clitoris, and are
named the profunda and dorsal arteries.
SCIATIC AND GLUTEAL ARTERIES. 429
V. SCIATIC ARTERY.
The sciatic artery, the largest branch of the internal iliac trunk, excepting
the gluteal, is distributed to the muscles on the back of the pelvis. It
descends upon the pelvic surface of the pyriformis muscle and the sacral
plexus of nerves; and, turning backwards beneath the border of that muscle,
it passes between it and the superior gemellns, and thus escapes from the
pelvis, along with the great sciatic nerve and the pudic artery, at the lower
part of the great sciatic foramen. Outside the pelvis, this artery lies in the
interval between the tuber ischii and the great trochanter, covered by the
gluteus maximus.
BRANCHES. The sciatic artery gives off several branches to the external rotator
muscles of the thigh, on which it lies, and to the great gluteus by which it is con-
cealed. Two others have received special names, viz., the following.
(a) The coccygeal, inclines inwards, and piercing the great sacro-sciatic ligament,
reaches the posterior surface of the coccyx, and ramifies in the fat and skin about
that bone.
(b) The other named branch, comes nervi iscliiadici, runs downwards, accompanying
the sciatic nerve, along which it sends a slender vessel.
Some of the branches of this artery are distributed to the capsule of the hip-joint ;
whilst others, after supplying the contiguous muscles, anastomose with the gluteal,
the internal circumflex, and the superior perforating arteries, in the upper part of the
long flexor muscles of the thigh..
VI. GLETTEAL ARTERY.
The gluteal artery, the largest branch of the internal iliac, is distributed
to the muscles on the outside of the pelvis. It inclines downwards to the
great sacro-sciatic foramen, and, escaping from the cavity of the pelvis,
between the contiguous borders of the middle gluteal and the pyriform
muscles, divides immediately into a superficial and a deep branch.
BRANCHES. (a) The superficial branch, running between the gluteus maximus and
gluteus medius, divides into ramifications which are most copiously distributed to the
gluteus maximus, and anastomose with the sciatic and posterior sacral arteries.
(b) The deep branch, situated between the gluteus medius and gluteus minimus,
runs in an arched direction forwards, and divides into two other branches. One of
these, the superior branch, follows the upper border of the gluteus minimus beneath
the middle gluteal muscle and the tensor of the fascia lata, towards the anterior iliac
spine, and, after having freely supplied the muscles between which it passes, anasto-
moses with the circumflex iliac and the ascending branches of the external circum-
flex arteries. The second or inferior branch descends towards the great trochanter,
supplies the gluteal muscles, and anastomoses with the external circumflex and the
sciatic arteries.
(c) A nutrient, branch enters the hip bone at the place where the artery emerges
from the pelvis.
VII. 1LIO-LUMBAR ARTERY.
The ilio-lumbar artery resembles in a great measure one of the lumbar
arteries. It passes outwards beneath the psoas muscle and the external
iliac vessels, to reach the margin of the iliac fossa, where it separates into a
lumbar and an iliac division. The first of these ramifies in the psoas and
quadratus muscles, communicating with the last lumbar artery, and fur-
nishing branches to the vertebral canal. The second or iliac division,
turning downwards and outwards, either in the iliacus muscle or between
it and the bone, anastomoses with the circumflex iliac artery, and even with
the external branches of the epigastric.
430
INTERNAL ILIAC ARTERY.
PECULIARITIES. The ilio-lumbar artery sometimes arises from the internal iliac,
above the division of that trunk ; and more rarely from the common iliac. The iliac
and lumbar portions sometimes arise separately from the parent trunk.
Fig. 294. ARTERIES OF THE BACK
OF THE PELVIS AND UPPER PART
OF THE THIGH (from Tieclemann).|
, crest of the ilium ; b, tuber-
osity of the ischium and lower
attachment of the great sacro-
sciatic ligament ; c, great tro-
chauter ; d, integument round the
anus ; e, great sciatic nerve ; 1,
trunk of the gluteal artery as it
issues from tbe great sacro-sciatic
foramen, the superficial branches
cut short, the deep arch seen pass-
ing round on the upper part of
the gluteus minimus muscle ; 2,
placed on the great sacm-sciatic
ligament, points to the pudic artery
at the place where it winds over
the back of the spine of ths ischium;
2', the continuation of the artery
towards the perinseum on the in-
side of the tuberosity and ram us
of the ischium ; 3, 3, the sciatic
artery, the upper figure placed on
the pyriformis muscle, the lower
on the great sciatic nerve ; 4, 4',
first perforating artery passing
through the upper part of the great
adductor muscle and anastomosing
with the posterior branch of the
internal circumflex artery, which
appears between the quadratus and
the adductor muscles ; 5 and 6,
part of the second and third per-
forating arteries.
When the lowest of the lumbar
arteries is wanting it is replaced by a branch from the ilio-lumbar, which is increased
in size, and by a small offset from the middle sacral artery.
VIII. LATERAL SACRAL ARTERIES.
The lateral sacral arteries are usually two in number on eacli side, though
occasionally they are united into one. Tbe two arteries arise close together
from the posterior division of the internal iliac. One is distributed upon
the upper, and the other upon the lower part of the sacrum.
Both arteries pass downwards, at the same time inclining somewhat
inwards, in front of the pyriform muscle and the sacral nerves, which they
supply with twig, and reach the inner side of the anterior sacral foramina.
Continuing to descend, the lower one appsoaches the middle line, and
anastomoses with the middle sacral artery.
Dorsal Branches. The lateral sacral arteries give off a series of branches
\vhich enter the anterior sacral foramina. Each of these, after having
furnished within the foramen a spinal branch, which ramifies on the bones
ami membranes in the interior of the sacral canal, escapes by the cor-
responding posterior sacral foramen, and is distributed upon the dorsal
surface of the eacrnm.
EXTERNAL ILIAC ARTERY.
431
EXTERNAL ILIAC ARTERY.
The external of the two arteries resulting from the division of the common
iliac forms a large continuous trunk, which extends downwards in the limb
as far as the lower border of the popliteus muscle ; but, for convenience of
description, it is named in successive parts of its course external iliac,
femoral, and popliteal.
The external iliac artery, larger than the internal iliac artery, is placed
within the abdomen, and extends from the division of the common iliac to
the lower border of Poupart's ligament, where the vessel enters the thigh,
and is named femoral. Descending obliquely outwards, its course through
the abdominal cavity may be marked by a line drawn from the left side of
the umbilicus to a point midway between the anterior superior spinous
process of the ilium and the symphysis pubi*. This line would also indicate
the direction of the common iliac artery, from which the external iliac is
directly continued.
The vessel is covered by the peritoneum and intestines. It lies along the
upper margin of the true pelvis, resting upon the inner border of the psoas
muscle. The artery, however, is separated from the muscle by the fascia
Fig. 295.
Fig. 295. VIEW OF
THE PRINCIPAL AR-
TERIES AND THEIR
DIVISIONS ON THE
EIGHT SIDE OF A
MALE PELVIS.
For the detailed de-
scription of this figure
see Fig. 288, p. 419.
2', the right external
iliac artery, accompa-
nied by the correspond-
ing vein 4', passing
below into the femoral
vessels under Poupart's
ligament ; 12, epi-
gastric artery winding
to the inside of + , + ,
the spermatic cord ;
the epigastric artery is
cut short superiorly ;
13, circumflex iliac
artery anastomosing
with 15, branches of
the ilio-lumbar ; 14,
spermatic artery and
vein descending to join
the spermatic cord ;
+ , within the pelvis,
the vas deferens de-
scending from the cord
towards the bladder.
iliaca, to which it
is bound together
with the external iliac vein, by the subperitoneal tissue.
432
EXTERNAL ILIAC ARTERY.
Relation to Vciuxj tOo. The external iliac vein lies at first behind the
artery with an inclination to the inner side ; bat, as both vessels approach
Poupart'a ligament at the fore part of the pelvis, the vein is on the same
plane with the artery and quite to the inner side, being borue forwards by
the bone. At a short distance from its lower end the artery is crossed by
the circumflex iliac vein.
Fig. 296. VIEW OF THE DISTRIBUTION
AND ANASTOMOSIS OF TUB EPIGASTRIC
AND INTKHNAL MAMMARY ARTEKIKS
(from Ticdeinann). |
For the detailed description of this
figure, see Fig. 265, p. b75.
7, placed on the transversalis muscle
above the internal inguinal aperture, points
to the last part of the external iliac artery
at the place where it gives origin to 8, the
epigastric and 9, the circumflex iliac ar-
tery: 10, anastomosis of the epigastric
artery and the abdominal branch of the in-
ternal mammary in and behind the rectos
muscle; 11, the spermatic cord receiving
the external spermatic branch from the
epigastric artery ; 12, femoral artery ; 13,
femoral vein ; 14, a lymphatic gland
closing the femoral ring.
Lrtrge lymphatic glands are found
resting upon the front and inner side
of the vessel ; and the spermatic
vessels descend upon it near its ter-
mination. A branch of the yenito-
crural nerve crosses it just above
Pou part's ligament.
BRANCHES. The external iliac
artery supplies some small branches
to the psoas mucle and the neigh-
bouring lymphatic glands, and, close
to its termination, two other branches
of considerable size, named the epi-
gastric and the circumflex iliac, which
are distributed to the walls of the
abdomen.
1. THE EPIGASTRIC ARTERY (in-
ferior epigastric) arises from the fore-
part of the external iliac artery,
usually a few lines above Poupart's
ligament. It, first inclines down-
wards, FO as to get on a level with
the ligament, and then passes ob-
liquely upwards and inwards between
the fascia transversalis and the
peritoneum, to reach the rectus
muscle of the abdomen. It ascends
almost vertically behind the rectus,
BRANCHES OF THE EXTERNAL ILIAC.
433
and rising within the sheath is placed between it and the muscle, and
terminates at some distance above the umbilicus in offsets which ramify
ia the substance of the muscle and anastomose with the terminal branches
of the internal mammary and inferior intercostal arteries.
The epigastric artery is accompanied by two veins, which unite into a
single trunk before ending in the external iliac vein.
In its course upwards from Poupart's ligament to the rectus muscle, the
artery passes close to the inner side of the internal abdominal ring ; and
the vas deferens, entering through the ring, turns behind the artery iii
descending into the pelvis.
BRANCHES. These are small, but numerous.
(a) The cremasteric artery, a slender branch, accompanies the spermatic cord, and
supplying the cremaster muscle and other coverings of the cord, anastomoses with the
spermatic artery.
(6) Several raa^culor branches ariss from each side of the epigastric artery, ramify
in the rectus muscle, and communicate with the branches of the lumbar and circum-
flex iliac arteries.
(c) Superficial branches perforate the abdominal muscles, and join beneath the skin
with branches of the superficial epigastric artery.
(d) The pubic is a small branch, which ramifies behind the pubes, and commu-
nicates by means of one or more descending twigs with a similar branch from the
obturator artery.
Fig. 297. VIEW OF THE RELATION OF
THIC VESSELS OF THE GROIN TO A
FEMORAL UERXIA, &c. (from E.
Quain).
Fig. 297.
In the upper part of the figure a
portion of the flat muscles of the
abdomen has been removed, displaying
in part the transversalis fascia arid
peritoneal lining of the abdomen ; in
the lower the fascia lata of the thigh is
in part removed and the sheath of the
femoral vessels opened : the sac of the
femoral hernial tumour has also been
opened.
ft, anterior superior spinons process
of the ilium ; &, aponeurosis of the ex-
ternal oblique muscle above the exter-
nal inguinal aperture ; c, the abdomi-
nal peritoneum and fascia trans-
versalis ; d, the iliac portion of the
fascia lata near the saphenic opening;
e, sac of a femoral hernia ; 1, points
to the femoral artery ; 2, femoral vein
at the place where it is joined by the
saphena vein ; 3, epigastric artery and
vein passing up towards the back of
the rectus muscle ; +, placed upon
the upper pait of the femoral vein
close below the common trunk of the
epigastric and an aberrant obturator artery ; the latter artery is seen in this case
close to the vein and between it and the neck of the hernial tumour.
to pass
2. THE CIRCUMFLEX ILIAC ARTERY, smaller than the preceding vessel,
arises from the outer side of the iliac artery near Poupart's ligament, and is
434 FEMORAL ARTERY.
directed outwards behind that band to the anterior superior iliac spine.
Following thence the crest of the hip- bone, the artery gives branches to the
iliacus muscle, furnishes others which are distributed to the abdominal
muscles, and anastomoses with the ilio-lumbar artery. In its course outwards
this artery lies in front of the trans versalis fascia, at the junction of this
with the fascia iliaca.
Two veins accompany the circumflex iliac artery ; these unite below into
a single vessel, which crosses the external iliac artery about an inch above
Poupart's ligament, and enters the external iliac vein.
The muscular branch is given off near the iliac crest, and ascends on the fore-part
of the abdomen between the transversalis and internal oblique muscles : having sup-
plied those muscles, it anastomoses with the lumbar and epigastric arteries. This
branch varies much in size, and is occasionally replaced by several smaller muscular
offsets.
PECULIARITIES. Size. In those rare cases in which the principal blood-vessel of
the lower limb is continued from the internal iliac (p. 441), the external iliac artery
is correspondingly diminished, and ends in the muscles of the front of the thigh,
taking the place of the profunda.
Branches. The usual number of two principal brandies of the external iliac artery
may be increased by the separation of the circumflex iliac into two branches, or by
the addition of a branch usually derived from another source, such as the internal
circumflex artery of the thigh or the obturator artery.
The epigastric artery occasionally arises higher than usual, as at an inch and a
half, or even two inches and a half, above Poupart's ligament; and it has been seen
to arise below that ligament from the femoral or from the deep femoral artery. The
epigastric frequently furnishes the obturator artery ; and two examples are recorded
in which the epigastric artery arose from an obturator furnished by the internal iliac
artery. (Monro, " Morbid Anatomy of the Human Gullet," &c., p. 427, A. K. Hessel-
bach, "Die sicherste Art des Bruchschnittes," &c.) In a single instance the epigas-
tric artery was represented by two branches, one arising from the external iliac, and
the other from the internal iliac artery. (Lauth, in " Velpeau's Medecine Operatoire,"
v. ii. p. 452.) Some combinations of the epigastric with the internal circumflex, or
with the circumflex iliac, or with both those vessels, have been noticed.
The circumflex iliac artery sometimes deviates from its ordinary position, arising
at a distance not exceeding an inch above Poupart's ligament. Deviations in the
opposite direction are more rarely met with ; it has in a few cases been observed to
arise below the ligament, from the femoral artery.
FEMORAL ARTERY.
The femoral artery is that portion of the artery of the lower limb which
lies in the upper two-thirds of the thigh, its limits being marked above by
Poupart's ligament, and below by the opening in the great adductor muscle,
after passing through which the artery receives the name popliteal.
A general indication of the direction of the femoral artery over the fore-
part and inner side of the thigh is given by a line reaching from a point
midway between the anterior superior iliac spine and the symphysis of the
pnbes to the inner side of the internal condyle of the femur. At the upper
part of the thigh, it lies along the middle of a depression between the
muscles covering the femur on the outer side, and the adductor muscles
on the inner side of the limb, which is known by the name of Scarpa's
triangle. In this situation the beating of the artery may be felt, and the
circulation through the vessel may be most easily controlled by pressure.
Below the upper third of the thigh it is crossed by the upper and inner
FEMORAL ARTERY.
Fig. 298.
Fig. 29S. ANTERIOR VIEW OF THE AR-
TERIKS OF THE PELVIS, THIUH AND KNEE
(from Tiedemann).
cr, anterior superior iliac spine ; b, tensor
A-aginse femoris muscle ; c, vastus iuternus ;
<1, tendon of the adductor ma^nus ; e, sar-
torius ; /, rectus muscle ; g, the colon lying
upon the left iliac artery ; 7i, urinary blad-
der ; 1, lower part of the abdominal aorta
dividing into the common iliac arteries ; 1',
middle sacral artery ; 2, left common iliac
artery ; 3, external iliac; 3', deep circum-
flex iliac branch ; 3", epigastric winding to
the inside of the spermatic cord, and giving
off 3'", its cremasteric branch; 4, femoral
artery, on the right side shown in Scarpa's
triangle, on the left exposed as far as
Hunter's canal ; 4', superficial circumflex
iliac and epigastric of the right side ; 4",
superficial pubic and inguinal branches ; 5,
profunda femoris artery, descending on the
left side behind the adductor longus ; 6,
external circumflex ; 6', its ascending or
gluteal branches; 6", its descending branches;
7, 7', internal circumflex artery ; 8, superior
perforating ; 8', second perforating branch ;
y, 9, muscular branches of the femoral ar-
tery ; 9', anastomotic branch ; 10 internal
superior articular branch of the popliteal; 10', inferior l>r;
border of the sartorius muscle which forms the outer wall of the triangle,
and which conceals the vessel in the remainder of its course. In the first
436
FEMORAL ARTERY.
part of its course the femoral artery is covered only by the slun and fascia
lata, and by the sheath which invests both the artery and vein, viz., the crural
sheath (p. 293). In the lower part of its course it is deeply placed, being
covered not only by the sartorius muscle, but by a dense stratum of
fibrous structure, which stretches across from the tendons of the long and
great adductors to the vastus internus muscle, and encloses the space called
Hunter : 's canal, in which the vessels lie.
The artery rests successively upon the following parts. First, upon the
psoas muscle, by which it is separated from the margin of the pelvis and the
capsule of the hip-joint ; next, it is placed in front of the pectineus muscle,
the deep femoral artery and vein being interposed ; afterwards, it lies upon
the long adductor muscle ; and lastly, upon the tendon of the great adductor,
the femoral vein being placed between the tendon and the artery. At the
lower part of its course, it has immediately on its outer side the vastus
internus muscle, which intervenes between it and the inner side of the
femur.
At the groin the artery, after having passed over the margin of the
pelvis, is placed slightly in front of or internal to the head of the femur ;
and at its lower end, the vessel lies close to the inner side of the shaft of
the bone ; but in the intervening space, in consequence of the projection
of the neck and shaft of the femur outwards, while the artery holds a
straight course, it is separated from the bone by a considerable interval.
Fig. 299.
Fig. 299. VIEW OP THE FEMORAL VKS-
SKLS, WITH THEIR SMALLER SUPERFICIAL
BRANCHES IN THE RIGHT GROIN (from R.
Quain). ^
- a, the integument of the abdomen ; b, the
superficial abdominal fascia; b\ the part
descending on the spermatic cord ; c, c, the
aponeurosis of the external oblique muscle ;
c', the same near the external abdominal
ring; c", the inner pillar of the ring ; d, the
iliac part of the fascia lata ; d 1 , the pubic
part ; e, c, the sheath of the femoial vessels
laid open, the upper letter is immediately
over the crural aperture ; c', placed on the
sartorius muscle partially exposed, points to
the margin of the saphenic opening; 1,
femoral artery, having the femoral vein 2,
to its inner side, and the septum of the
sheath shown between the two vessels ; 3,
the principal saphenous vein ; 3', its anterior
branches ; 4, the superficial circumflex iliac
vein and arterial branches to the glands of
the groin ; 5, the superficial epigastric vein ;
6, the external pudic arteries and veins ; 7,
to 8, seme of the lower inguinal glands re-
ceiving twigs from the vessels ; 9, internal,
10, middle, and 11, external cutaneous
nerves.
Relation to Veins. The femoral
vein is very close to the artery, both being enclosed in the same sheath, and
separated from each other only by a thin partition of fibrous membrane.
At the groin the vein lies in the same plane as the artery, and on the inner
side ; but gradually inclining backwards, it is placed behind it at the
SUPERFICIAL INGUINAL BRANCHES. 437
lower end of Scarpa's space, and afterwards gets somewhat to the outer
side. The deep femoral vein, near its termination, crosses behind the
femoral artery ; and the long saphenous veiu, as it ascends on the fore part
of the limb, lies to the inner side ; but it not unfrequently happens that a
superficial vein of considerable size ascends for some space directly over the
artery.
Relation to Nerves. At the groin the anterior crural nerve lies a little to
the outer side of the femoral artery (about a quarter of an inch), separated
from the vessel by some fibres of the psoas muscle and by the sheath and
fascia Lower down in the thigh, the long saphenous nerve accompanies the
artery until this vessel perforates the adductor magnus. There are likewise
small cutaneous nerves which cross the artery.
BRANCHES. The femoral artery gives off the following branches : some
small and superficial, which are distributed to the integument and glands
of the groin and ramify on the lower part of the abdomen, viz., the ex-
ternal pudic (superior and inferior), the superficial epigastric, and the super-
ficial circumflex: iliac ; the great nutrient artery of the muscles of the thigh,
named the deep femoral ; several muscular branches ; and lastly, the anasto-
rnotic artery, which descends on the inner side of the knee-joiut.
The portion of the femoral artery extending from its commencement to the origin
of the deep femoral, a part varying from an inch to two inches in length, is some-
times distinguished by surgical writers as the common femoral, and described as
dividing into the superficial and deep femoral arteries.
I. SUPERFICIAL INGUINAL BRANCHES. The external pudic arteries arise
either separately or by a common trunk from the inner side of the femoral
artery. The superior, the more superficial branch, courses upwards and in-
wards to the pubic spine, crosses the external abdominal ring, passing in the
male over the spermatic cord, and is distributed to the integuments on the
lower part of the abdomen, and on the external organs of generation. The
inferior branch, more deeply seated, extends inwards, resting on the pec-
tin eus muscle, and covered by the fascia lata, which it pierces on reaching
the inner border of the thigh, and is distributed to the scrotum in the male,
or to the labium in the female, its branches inosculating with those of the
superficial perineal artery.
The superficial epigastric artery, arising from the femoral vessel, about
half an iuch below Poupart's ligament, passes forwards through the fascia
lata, and runs upwards on the abdomen in the superficial fascia covering
the external oblique muscle. Its branches, ascending nearly as high as the
umbilicus, anastomose with superficial branches of the epigastric and internal
mammary arteries.
The superficial circumflex iliac artery runs outwards in the direction of
Poupart's ligament towards the iliac spine, across the psoas and iliacus
muscles : to both of these it gives small branches, as also some others which
pierce the fascia lata ; it is distributed to the integument.
All the preceding arteries give small branches to the lymphatic glands in
the groin.
II. THE DEEP FEMORAL ARTERY (profunda femoris) the principal nutri-
tious vessel of the thigh, is an artery of considerable calibre, being nearly
equal in size to the continuation of the femoral after the origin of this great
branch. It usually arises from the outer and back part of the femoral
artery, between an inch and two inches below Poupart's ligament. At its
438
FEMORAL ARTERY.
commencement, it inclines outwards in front of the iliacus muscle, to such an
extent as to be visible for a short distance external to the femoral artery ; it
then runs downwards and backwards behind that vessel, and passing behind
the long adductor muscle, between it and the great adductor, near their
femoral attachments, divides into terminal branches, which pierce the great
adductor, and ramify in the muscles at the back and outer part of the
thigh.
Fig. 300. DEEP VIEW OF THE FEMO-
RAL ARTERY AND ITS BRANCHES ON
THE LEFT SIDE (from R. Quain). |
The sartorius muscle has been re-
moved in part, so as to expose the
artery in the middle third of the thigh,
a, the anterior superior iliac spine ; b,
the aponeurosis of the external oblique
muscle near the outer abdominal ring,
from which the spermatic cord is seen
descending towards the scrotum ; c,
the upper part of the rectus femoris
muscle ; d, adductor longus ; e, fibrous
sheath of Hunter's canal covering the
artery ; 1, femoral artery ; 1', femoral
vein divided and tied close below Pou-
part's ligament; 2, ptofnnda femoris
artery ; 3, anterior crural nerves ; 4,
internal circumflex branch ; 5, super-
ficial pudic branches ; 6, external cir-
cumflex branch, with its ascending
transverse and descending branches
separating from it ; 6', twigs to the
rectus muscle; 7, branches to the
vastus iuternus muscle ; 8, and 9,
some of the muscular branches of thu
femoral.
This artery lies successively in
front of the iliacu*, pectineus
adductor brevis and adductor
magnus muscles. The femoral
and profunda veins and the long
adductor muscle are interposed
between it and the femoral trunk.
The named branches of the
deep femoral artery are the ex-
ternal and the internal circumflex,
and the perforating arteries.
1. The external circumflex ar-
tery, a branch of considerable
size, arises from the outer side of
the profuuda near its origin, and
passing outwards for a short dis-
tance beneath the sartorius and rectus muscles, and through the divisions
of the anterior crural nerve, divides into three sets of branches.
(a} Transverse branches pass outwards over the crureus muscle, pierce the vastus
externus, so as to get between it and the femur, just below the great trochanter, and
BRANCHES OF THE PROFUXDA. 439
reach the back part of the thigh, where they anastomose with the internal circumflex
and the perforating branches of the deep femoral, and with the gluteal and sciatic
branches of the internal iliac.
(b) Ascending branches, directed upwards beneath the sartorius and rectus, and
afterwards under the tensor muscle of the fascia lata, communicate with the terminal
branches of the gluteal, and with some of the external descending branches of the
circumflex iliac artery.
(c) Descending branches incline outwards and downwards upon the extensor
muscles of the knee, covered by the rectus muscle. They are usually three or four in
number, some being of considerable size ; most of them are distributed to the muscles
on the fore part of the thigh, but one or two can be traced beneath the vastus externu.s
muscle as far as the knee, where they anastomose with the arterial branches sur-
rounding that joint.
2. The internal circumflex artery, smaller than the external circumflex,
arises close to that branch from the inner and hinder part of the deep
femoral aitery, and is directed backwards between the pectineus and the
psoas muscles to the inner side of the femur, so that only a small part of it
can be seen without displacing these muscles. On reaching the tendon of
the external obturator, along which the vessel passes to the back of the
thigh, it divides into two principal branches.
(a) The anterior branch is distributed partly to the adductor brevis and gracilis,
and partly to the external obturator muscle, near which it anastomoses with the
obturator artery.
(b) The posterior branch passes backwards above the small trochanter, and
appears on the back of the limb, between the quadratus femoris and great adductor
muscles, where it supplies the hamstring muscles, and anastomoses with the sciatic
artery and with the superior perforating branches of the deep femoral artery.
An articular vessel, arising from the posterior branch opposite the hip joint, enters
the joint through the notch in the acetabulum, beneath the transverse ligament, and
supplies the adipose tissue and the synovial membrane in that articulation. Some
offsets are guided to the head of the femur by the round ligament. In some instances
the articular branch is derived from the obturator artery ; and sometimes the joint
receives a branch from both sources.
3. The perforating arteries (perforantes) are branches which reach the
back of the thigh, by perforating the adductor brevis and adductor magnus
muscles ; they are four in number, including the terminal branch of the
parent vessel.
(a) The first perforating artery passes backwards below the pectineus muscle,
through the fibres of the adductor brevis and magnus, and is distributed to both
these adductor muscles, to the biceps and great gluteal muscles, and communicates
with the sciatic and internal circumflex arteries.
(b) The second perforating artery, considerably larger than the first, passes
through the adductor brevis and magnus ; after which it divides into ascending and
descending branches, which ramify in the hamstring muscles, and communicate with
the other perforating branches ; an offset from it, named the nutrient artenj of the
femur, enters the medullary foramen of that bone.
(c) The third perforating artery pierces the adductor magnus muscle, below the
insertion of the adductor longus, and is distributed in a manner similar to the second
perforating artery.
(d) The fourth perforating artery, the termination of the deep femoral artery,
passing backwards close to the liuea aspera, is distributed to the short head of the
biceps and to the other hamstring muscles, and communicates with branches of the
popliteal artery, and with the lower perforating arteries.
III. MUSCULAR BRANCHES OF THE FEMORAL ARTERY. In its course along
the thigh, the femoral artery gives off several branches to the contiguous
440
FEMORAL ARTERY.
muscles. They vary in number from two to seven. They supply the
sartorius and the vastus internus, with other muscles which are close to
Fig. 301.
of the fibres of the vastus internus muscle
Fig. 301. POSTERIOR VIEW OP
THE ARTERIES OF THE PELVIS,
THIGH, AND POPLITEAL SPACE
(from Tiedemann). \
a, the iliac cresl ; b, the great
sacro-sciatic ligament attached to
the tuberosity of the ischium ; c,
great trochanter ; d, the integu-
ment close to the anus ; c, great
sciatic nerve ; f, the line from this
letter crosses the tendons of the
inner hamstring muscles ; g, head
of the fibula ; 1, gluteal artery ;
2, pudic ; 3, sciatic artery, giving
its branches to the short external
rotator muscles, to the sciatic
nerve, and to the upper part of
the long flexor muscles ; 4, first
perforating artery; 4', its branches
to the flexor muscles ; 5, branches
of the second perforating ; 6,
branches of the third perforating;
7, popliteal artery, near this the
origin of the superior muscular
branches; 8, placed on the ten-
don of the adductor magnus near
the origin of the superior articular
branches ; 9, the anastomosis of
the external superior articular
with other branches ; 10,thesural
branches ; 11, the recurrent of
the anterior tibial artery.
the femoral artery : their size
appears to bear an inverse
proportion to that of the
descending branches of the
external circumflex artery.
IV. ANASTOMOTIC ARTERY.
Close to its termination
the femoral artery gives off
a branch, canstaut but of
moderate size, named the
anastomotic artery (anastomo-
tica magnet), which descends
in the same line as the femoral
artery itself (see fig. 298).
Arising from that vessel when
about to enter the popliteal
space, it descends upon the
tendon of the adductor mag-
nus to the inner coudyle of
the femur, giving off several
branches, and covered by some
it finally anastomoses with the
POPLITEAL ARTERY. 441
internal articular arteries, and with the recurrent branch of the anterior
tibial artery.
(a) A superficial branch accompanies the saphenous nerve beneath the sartorius
muscle to the integument on the inner side of the knee.
(b) The external branch, arising from the lower part of the vessel, crosses over the
femur, supplies offsets to the knee-joint, and forms an arch a little above the articular
surface, by anastomosing with the superior external articular artery.
PECULIARITIES OP THE FEMORAL ARTERY AND BRANCHES. Trunk. Four instances
have been recorded of division of the femoral artery below the origin of the profunda
into two vessels, which subsequently were reunited near the opening of the adductor
magnus so as to form a single popliteal artery. In all these cases, the arrangement
of the vessels appears to have been similar. To one of them (that first observed)
special interest is attached, inasmuch as it was met with in a patient operated upon
for popliteal aneurism. (This case was treated by Charles Bell, and recorded in " The
London Medical and Physical Journal," vol. IvL p. 134. London, 1826.)
The femoral artery is occasionally replaced at the back of the thigh by a trunk
continuous with the internal iliac. Having passed from the pelvis through the
large sacro-sciatic notch, this trunk accompanies the great sciatic nerve along the
back of the thigh to the popliteal space, where its connections and termination become
similar to those of the vessel presenting the usual arrangement. Four examples of
this deviation from the common state of the blood-vessel have been recorded. Refe-
rence is made to these in a Paper in vol. 36 of the Medico-Chirurgical Transactions,
giving an account of a specimen of remarkable deformity of the lower limbs of a
man in whom the artery was so transposed on both sides.
Branches. The deep femoral is occasionally given off from the inner side of the
parent trunk, and more rarely from the back part of the vessel. Occasionally it
arises at a distance of less than an inch, and sometimes of more than two inches,
below Poupart's ligament. It was even found by Richard Quain arising, in one
instance, above Poupart's ligament, and in another four inches below it ; but in the
latter instance the internal and external circumflex arteries did not arise from the
profunda.
The external circumflex branch sometimes arises directly from the femoral artery ;
or it may be represented by two branches, of which, in most cases, one proceeds from
the femoral, and one from the deep femoral : both branches, however, have been
seen to arise from the deep femoral, and much more rarely, both from the femoral
artery.
The internal circumflex branch may be transferred'to the femoral artery above the
origin of the profunda. Examples have also been met with in which the internal
circumflex arose from the epigastric, from the circumflex iliac, or from the external
iliac artery.
POPLITEAL ARTERY.
The popliteal artery, placed at the back of the knee-joint, extends along
the lower third of the thigh and the upper part of the leg, reaching from the
opening in the great adductor to the lower border of the popliteus muscle.
It is continuous above with the femoral, and divides at the lower end into
the anterior and posterior tibial arteries.
This artery at first inclines from the inner side of the limb to reach a
point behind the middle of the knee-joint, and thence continues to descend
vertically to its lower end. Lyiug deeply in its whole course, it is covered
for some distance at its upper end by the semimembranosus muscle ; a little
above the knee it is placed in the popliteal space ; interiorly it is covered
for a considerable distance by the gastrocnemius muscle ; and at its termi-
nation by the upper margin of the soleus muscle.
At first the artery lies close to the inner side of the femur ; in descending,
442
POPLITEAL ARTERY.
it is separated by an interval from the flat or somewhat hollowed triangular
surface at the lower end of the bone ; it then rests on the posterior ligament
of the knee-joint, and afterwards on the popliteus muscle.
Edation to Veins. The popliteal vein lies close to the artery, behind
and somewhat to the outer side till near its termination, where it crosses the
artery and is placed somewhat on the inner side. The vein is frequently
double along the lower part of the artery, and, more rarely, also at the
upper part. The short saphenous vein, ascending into the popliteal space
over the gastrocnemius muscle, approaches the artery as it is about to ter-
minate in the popliteal vein.
Relation to the Nene. The internal popliteal nerve lies at first to the
outer side of the artery, but much nearer to the surface than the vessel :
the nerve afterwards crosses over the artery, and is placed behind and to
the inner side below the joint.
BRANCHES. The branches of the popliteal artery may be arranged in two
sets, viz. the muscular and the articular.
1. The muscular brandies are divided into a superior and an inferior
group.
(a) The superior branches, three or four in number, are distributed to the lower
ends of the hamstring muscles, and also to the vasti muscles, and anastomose with the
perforating and articular arteries.
Fig. 302.
Fig. 302. VIEW OF THE POPLITEAL ARTERY AND
BRANCHES IN THE RIGHT LEG (from Tiedemann).
ITS
a, biceps muscle ; Z>, semimembranosus ; c, semi-
tendinosus ; 1, the popliteal artery ; 2, 3, the superficial
sural branches ; 4, the outer, 5, the inner superior
articular branch ; 6, the superior muscular ; 7, the
inferior muscular or deep sural branches.
(b) The inferior muscular branches, or sural arteries,
usually two in number, and of considerable size, arise
from the back of the popliteal artery, opposite the
knee-joint, and enter, one the outer, and the other the
inner head of the gastrocnemius muscle, which they
supply, as well as the fleshy part of the plantaris
muscle.
Over the surface of the gastrocnemius will be found
at each side, and in the middle of the limb, slender
branches, which descend a considerable distance along
the calf of the leg, and end in the integument. These
small vessels (superficial sural) arise separately from
the popliteal artery, or from some of its branches.
2. The articular arteries. Two of these pass
off nearly at right angles from the popliteal
artery, one to each side, above the flexure of
the joint, whilst two have a similar arrange-
ment below it, and a fifth passes from behind into the centre of the joint.
(a) The upper internal articular artery winds round the femur just above
the inner condyle ; and, passing under the tendon of the great adductor and
the vastus internus, divides into two branches ; one of these, comparatively
superficial, enters the substance of the vastus, and inosculates with the anas-
tomotic branch of the femoral, and with the lower internal articular artery.
BRANCHES OF THE POPLITEAL ARTERY.
443
The other branch runs close to the femur, ramifies upon it, and also on
the knee-joint, and communicates with the upper external articular artery.
(6) The upper external articular artery passes outwards a little above
the outer condyle of the femur, under cover of the biceps muscle, and,
after perforating the intermuscular septum, divides into a superficial and a
deep branch. The latter, lying close upon the femur, spreads branches
upon it and the articulation, and communicates with the preceding vessel,
with the anastomotic of the femoral, and with the lower external articular
artery ; the superficial branch descends through the vastus to the patella,
anastomosing with other branches and assisting in the supply of the joint.
(c) The lower internal articular artery passes downwards below the
internal tuberosity of the tibia, lying between the bone and the internal
lateral ligament ; its branches ramify on the front and inner part of the
joint, as far as the patella and its ligament.
(d) The lower external articular artery takes its course outwards, under
cover of the outer head of the gastrocnemius in the first instance, arid
afterwards under the external lateral ligament of the knee and the tendon
of the biceps muscle, passing above the head of the fibula. Having reached
the fore part of the joint, it divides near the patella into branches, some of
which communicate with the lower articular artery of the opposite side, and
with the recurrent branch from the anterior tibia! ; whilst others ascend,
and anastomose with the upper articular arteries.
In this manner the four articular branches form at the front and sides of
the knee-joint a close network of vessels.
Fig. 303.
Fig. 303. ANTERIOR VIEW OP THE DEEP ARTERIAL
BRANCHES SURROUNDING THE KNEE-JOINT AND THEIR
ANASTOMOSES (from Tiedemann). \
a, the patellar articular surface of the femur ; 5, the
posterior or cartilaginous surface of the patella which,
with the ligamentum patellae, has been turned down ; c,
the head of the fibula ; 1, and 2, branches of the internal
superior articular branch of the popliteal ramifying on
the periosteum, and anastomosing with the external
superior articular branch 3, and with other arteries
within and below the joint; 4, branches of the internal
inferior articular ; 5, external inferior articular ; 6, re-
current of the anterior tibial artery.
(e) The middle or azygos articular artery, is a
small branch which arises opposite the flexure of
the joint, and, piercing the posterior ligament,
supplies the crucial ligaments and other structures
within the articulation.
PECULIARITIES. Deviations from the ordinary condi-
tion of the popliteal artery are not frequently met with.
The principal departure from the ordinary arrangement
consists in its high division into terminal branches.
Such an early division has been found to take place most
frequently opposite the flexure of the knee-joint, and not higher.
In a few instances, the popliteal artery has been seen to divide into the anterior
tibial and peroneal arteries the posterior tibial being small or absent. In a single
case, the popliteal artery was found to divide at once into three terminal vessels, viz.,
the peroneal and the anterior and posterior tibial arteries.
The azygos articular branch frequently arises from one of the other articular
G G 2
444 POSTERIOR TIBIAL ARTERY.
branches, especially from the upper and external branch. There are sometimes several
small middle articular branches.
POSTERIOR TIBIAL ARTERY.
The posterior tibial artery is situated along the back part of the leg,
between the superficial and deep layers of muscles, and is firmly bound
down to the deep muscles by the fascia which covers them. It eKtends
from the lower border of the popliteus muscle, where it is continuous with
the popliteal artery, down to the inner side of the calcaneum, where it
terminates beneath the origin of the abductor pollicis muscle by dividing
into the external and internal plantar arteries.
Placed at its origin opposite the interval between the tibia and fibula,
it approaches the inner side of the leg as it descends, and lies behind the
tibia ; at its lower end it is placed midway between the inner malleolus
and the prominence of the heel. Very deeply seated at the upper part,
where it is covered by the fleshy portion of the gastrocnemius and soleus
muscles, it becomes comparatively superficial towards the lower part, being
there covered only by the integument and two layers of fascia, and by the
annular ligament behind the inner malleolus. It lies successively upon the
tibialis posticus, the flexor loiigus digitorum, and, at its lower end, directly
on the tibia and the ankle-joint. Behind the ankle, the tendons of the tibialis
posticus and flexor longus digitorum lie between the artery and the internal
malleolus ; whilst the tendon of the flexor longua pollicis is to the outer
side of the artery.
Relation to the Veins and Nerve. The posterior tibial artery, like the
other arteries below the knee, is accompanied by two vense comites. The
posterior tibial nerve is at first on the inner side of the artery, but in the
greater part of its course the nerve is close to the outer side of the vessel.
BRANCHES. The posterior tibial artery furnishes numerous small branches,
and one large branch the peroneal artery.
SMALL BRANCHES. (a) Several muscular branches arise from the posterior tibial
artery, and are distributed principally to the deep-seated muscles in its neighbour-
hood, besides one or two of considerable size to the inner part of the soleus muscle.
(6) The nutrient artery of the tibia, which is the largest of its kind in the bodj r ,
arises from the posterior tibial artery near the commencement, and, after giving small
branches to the muscles, enters the nutrient foramen in the bone, and ramifies on
the medullary membrane. This vessel not unfrequently arises from the anterior
tibial artery.
(c) A communicating branch from the peroneal artery, passing transversely, joins
the posterior tibial about two inches above the ankle-joint.
THE PERONEAL ARTERY lies deeply along the back part of the leg, close
to the fibula. Arising from the posterior tibial artery about an inch below
the lower border of the popliteus muscle, it inclines at first obliquely
towards the fibula, and then descends nearly perpendicularly along that bone
and behind the outer ankle, to reach the side of the os calcis. In the
upper part of its course, this artery is covered by the soleus muscle and the
deep fascia, and afterwards by the flexor longus pollicis, which is placed over
it as far as the outer malleolus ; below this point, the vessel is covered only
by the common integument and the fascia. The peroneal artery rests at
first against the upper part of the tibialis posticus muscle, and afterwards, in
the greater part of its course, it is surrounded by fibres of the flexor longus
pollicis, lying close inside the projecting posterior ridge of the fibula. De-
PEROXEAL ARTERY.
445
scending beyond the outer malleolus, it terminates in branches on the outer
surface and back of the os calcis.
Fig. 304. DEEP POSTERIOR VIEW OF THE ARTERIES OP Fig. 304.
TIIE LEQ (from Tiedeinann).
a, insertion of the adductor magnus muscle ; b, origin
of the inner head of the gastrocnemius ; c, outer head
and plantaris ; d, tendon of the semimembranosus
muscle; e, popliteus; /, upper part of the soleus divided
below its origin from the head of the fibula ; g, peronens
longus; h, flexor longus pollicis; i, flexor communis
digitorum ; 1, upper part of the popliteal artery ; 2,
origin of the superior articular branches ; 3, origin of
the inferior articular branches ; the middle or azygos
branch is seen between these numbers ; 4, division of
the popliteal artery into anterior and posterior tibial
arteries ; 5, 5', posterior tibial ; 6, peroneal artery ; 6',
its continuation as posterior peroneal ; between 5', and
6', the communicating branch ; 7, calcaneal branches ; 8,
external branches of the metatarsal of the dorsalis pedis
artery.
The peroneal artery gives off the following
branches.
(a) Muscular branches from the upper part of the
peroneal artery pass to the soleus, the tibialis posticus,
the flexor longus pollicis, and the peronei muscles.
(b) A nutrient artery enters the fibula.
(c) The anterior peroneal artery arises about two
inches above the outer malleolus, and, immediately
piercing the interosseous membrane, descends along
the front of the fibula, covered by the peroneus tertius
muscle, and, dividing into branches, reaches the outer
ankle, and anastomoses with the external malleolar
branch of the anterior tibial artery. It supplies vessels
to the ankle-joint, and ramifies on the front and outer
side of the tarsus, inosculating more or less freely with
the tarsal arteries.
(d) The terminal branches anastomose with the
external malleolar and with the tarsal arteries on the
outer side of the foot ; and behind the os calcis with
ramifications of the posterior tibial artery.
(e) The communicating branch, lying close behind
the tibia, about two inches from its lower end, is a
transverse branch situated close to the bones, which
connects the peroneal with the posterior tibial artery.
PECULIARITIES. The posterior tibial artery, as well
as the anterior tibial, is lengthened in those instances
in which the popliteal artery divides higher up than
usual. Not unfrequently the posterior tibial artery is
diminished in size, and is subsequently reinforced
either by a transverse branch from the peroneal in the
lower part of the leg, or, in rare instances, by two trans-
verse vessels, one crossing close to the bone, and one
over the deep muscles. In other instances the posterior
tibial may exist only as a short muscular trunk in the
upper part of the leg, while an enlarged peroneal
artery takes its place from above the ankle downwards into the foot.
The peroneal artery has been found to arise lower down than usual, about three
446
PLANTAR ARTERIES.
inches below the popliteus muscle ; and, on the contrary, it sometimes commences
higher up from the posterior tibial, or even from the popliteal artery itself. In
some cases of high division of the popliteal artery, the peroneal artery is trans-
ferred to the anterior tibial. It more frequently exceeds than falls short of the
ordinary dimensions, being enlarged to reinforce the posterior tibial. In those rare
instances in which it is lost before reaching the lower part of the leg, a branch of the
posterior tibial takes its place. The anterior peroneal branch is sometimes enlarged to
compensate for the small size of the anterior tibial artery in the lower part of the
leg, or to supply the place of that artery on the dorsum of the foot ; or it may be
absent and be replaced by the anterior tibial. In a singular case, recorded by Otto,
the peroneal artery was wholly wanting.
PLANTAR ARTERIES.
The external and internal plantar arteries are the branches into which, the
posterial tibial divides in the hollow of the calcaneurn, where it is covered
by the origin of the abductor pollicis.
Fig. 305.
Fig. 305. SUPERFICIAL VIEW OP THE ARTERIES IN
THE SOLE OF THE RIGHT FOOT (from Tiedemann). g
a, tuberosity of the calcaneum close to the origin of
the flexor brevis digitorum (cut short) and the ab-
ductor pollicis, of which a part is removed to show
the long flexor tendons and plantar arteries ; b, ab-
ductor pollicis ; c, abductor minimi digiti ; d, tendon
of the flexor pollicis longus ; e, tendon of the flexor
coraraunis longus ; e\ its four slips, close to the lum-
bricales muscles, passing on to perforate the tendons
of the flexor brevis ; /, flexor accessorius ; g, flexor
brevis minimi digiti : 1, posterior tibial dividing into
the plantar arteries ; 2, 2', external plantar ; 3, in-
ternal plantar ; 3', the same passing forward to com-
municate with 4, the internal plantar digital branch
for the great toe ; 5, first digital or external plantar
branch to the fifth toe ; 6, placed in the angle
of division of the second plantar digital artery,
between the fourth and fifth toes ; 7, the third
plantar digital artery dividing similarly between the
third and fourth toes ; 8, the fourth plantar digital
artery dividing similarly between the second and third
toes ; 9, the plantar digital artery dividing similarly
between the first and second toes ; 1 0, internal plantar
artery of the great toe ; 11, calcaneal branches of the
plantar arteries, anastomosing with 12, the calcaneal
branches of the posterior peroneal artery.
The internal plantar artery, much smaller
than the external, is directed forwards, along
the inner side of the foot. Placed at first
under cover of the abductor pollicis, it passes
forwards in the groove between that muscle
and the short flexor of the toes, near the line separating the middle from
the inner portion of the plantar fascia, and on reaching the extremity of
the first metatarsal bone, considerably diminished in size, it terminates by
running along the inner border of the great toe, anastomosing with the
digital branches.
BRANCHES. The internal plantar artery gives off numerous small twigs, which
may be distinguished in sets as follows : (a) muscular branches to the abductor
EXTERNAL PLANTAR ARTERY.
447
pollicis and flexor brevis digitorum ; (b) offsets which incline towards the inner
border of the foot, and communicate with branches of the dorsal arteries;
and (c) cutaneous offsets which appear in the furrow between the middle and inner
portions of the plantar fascia.
The external plantar artery, of considerable size, at first inclines outwards
and then forwards, to reach the base of the fifth metatarsal bone : it then
turns obliquely inwards across the foot, to gain the interval between the
bases of the first and second metatarsal bones, where it joins, by a com-
municating branch, with the dorsal artery of the foot ; and thus is com-
pleted the plantar arch, the convexity of which is turned forward. At
first the artery is placed, together with the external plantar nerve, between
the calcaneum and the abductor pollicis ; further on it lies between the
flexor brevis digitorum and flexor accessorius. As it turns forwards it lies
in the interval between the short flexor of the toes and the abductor of the
little toe, being placed along the line separating the middle from the external
portion of the plantar fascia, and covered by that membrane. The re-
mainder of the artery, which turns inwards and forms the plantar arch, is
placed deeply against the interosseous muscles, and is covered by the flexors
of the toes and the lumbricales muscles.
BRANCHES.
A. In its course to the fifth metatarsal bone the external plantar artery gives
off (a) branches to the skin of the heel; (b) numerous muscular branches; (c) small
Fig. 306.
J2
Fig. 306. DEEP VIEW OF THE ARTERIES IN THE SOLE
OP THE RIGHT FOOT (from Tiedemann).
All the muscles have been removed, a, the calcaneal
tuberosity ; &, the scaphoid bone and end of the calcaneo-
scaphoid ligament ; c, to , ealcaneo-cuboid ligament ;
d, its deep part ; e, scaphoido-cuneiform ligament ; /,
one of the sesamoid bones of the great toe ; 1, posterior
tibial artery dividing into the plantar arteries ; 2, 2',
external plantar artery ; 2', 2", deep plantar arch termi-
nating by communication with the dorsal artery of the
foot ; 3, 3', internal plantar artery ; 3", its com-
munication with the internal digital of the great toe ; 4,
branches of the internal plantar to the inside of the foot ;
5, 5', first digital or external plantar branch of the fifth
toe ; 6, second plantar digital artery ; 6', interval of the
division of the same between the fourth and fifth toes ;
7, third plantar digital ; 7', its distribution to the third
and fourth toes ; 8, fourth plantar digital ; 8', its dis-
tribution to the second and third toes ; 9, fifth plantar
digital ; 9', its distribution to the first and second toes ;
10, internal plantar digital branch of the great toe ;
at the upper numbers, 6, 7, and 8, the posterior per-
forating branches of the interosseous arteries are par-
tially indicated; at 2", the large communication between
the plantar arch and the dorsalis pedis artery ; above
6', 7', and 8', are situated the anterior perforating
arteries, not represented in the figure; 11, and 12,
calcaneal branches of the plantar and posterior peroneal
arteries.
offsets which run outwards over the border of the foot,
and anastomose with the dorsal arteries ; and (d) others
which appear in the furrow between the middle and outer divisions of the plantar
fascia.
448 ANTERIOR TIBIAL ARTERY.
B. From the plantar arch are given off the following more important
branches.
(a) The posterior perforating branches, three in number, pass upwards
through the back part of the three outer interosseous spaces, between the
heads of the dorsal interosseous muscles, and on reaching the dorsum of the
foot inosculate with the interosseous branches of the metatarsal artery.
(6) The digital branches are four in number. The first digital branch
inclines outwards from the outermost part of the plantar arch, opposite the
end of the fourth metatarsal space, crosses under cover of the abductor
minimi digiti, and runs along the outer border of the phalanges of the little
toe. The second digital branch passes forwards along the fourth metatarsal
space, and near the cleft between the fourth and fifth toes divides into two
vessels, which course along the contiguous borders of those toes, and end on
the last phalanges. The third digital branch is similarly disposed of on the
fourth and third toes. The fourth ends in like manner on the third and
second toes.
The digital artery which supplies the opposed sides of the first and second
toes, and that which runs on the inner side of the first toe, arise deeply
between the first and second metatarsal bones, usually from that part of the
arch which is formed by the end of the dorsal artery of the foot.
Thus, as in the fingers, collateral arteries pass along the sides of the flexor
surface of each of the toes. Near the base of the last phalanx these
inosculate so as to form an arch, from the convexity of which minute vessels
pass forwards to the extremity of the toe, and to the matrix of the nail.
An anterior perforating branch is sent upwards by each of the digital arteries of the
three outer interspaces near its bifurcation, to communicate with the corresponding
digital branch of the metatarsal artery of the dorsum of the foot.
PECULIARITIES. The posterior perforating branches, which are usually very small
vessels, are sometimes enlarged, and furnish the interosseous arteries on the upper
surface of the foot ; the metatarsal branch of the dorsal artery, from which the inter-
osseous arteries are usually derived, being in that case very small.
ANTERIOR TIBIAL ARTERY.
The anterior tibial artery, placed along the fore part of the leg, is at first
deeply seated, but gradually approaches nearer to the surface as it descends.
It extends from the division of the popliteal artery to the bend of the
ankle ; whence it is afterwards prolonged to the interval between the first
and second metatarsal bones, under the name of dorsal artery of the foot.
The anterior tibial artery is at first directed forwards to reach the anterior
surface of the interosseous ligament, passing through the divided upper end
of the tibialis posticus, and through the interval left unoccupied by the in-
terosseous ligament. It then extends obliquely downwards to the middle of
the ankle-joint, in a direction which may be nearly indicated by a line
drawn from the inner side of the head of the fibula to midway between the
two malleoli. Lying with the tibialis anticus on its inner side, and having
the extensor communis digitorum and, lower down, the extensor proprius
pollicis on its outer side, the vessel is deeply placed at the upper part of
the leg, where those muscles are fleshy ; but it is comparatively superficial
below, between their tendons, and comes forward upon the tibia. At the
bend of the ankle it is covered by the annular ligament, and is crossed from
without inwards by the tendon of the extensor proprius pollicis. In its
BRANCHES OF THE ANTERIOR TIBIAL.
449
oblique course downwards the anterior tibial artery lies at first close to the
Fig. 307. ANTERIOR VIEW OP THE ARTERIES OF THE
LEG AND DORSUM OF THE FOOT (from Tiedemann). \ Fig. 307.
The tibialis anticus muscle is drawn towards the inner
side so as to bring the anterior tibial artery into view ;
the extensor proprius pollicis, the long common extensor
of the toes, and the peroneus tertius muscles in their
lower part, and the whole of the extensor communis
brevis, have been removed. 1, external superior articular
branch of the popliteal artery, ramifying on the parts
surrounding the knee, and anastomosing with the other
articular branches and with 2, the recurrent branch of
the anterior tibial artery ; 3, 3, anterior tibial, giving off
muscular branches on each side ; 4, dorsal artery of
the foot ; 5, external anterior malleolar artery coming
off from the anterior tibial, and anastomosing with
the anterior peroneal artery which is seen descending
upon the lower part of the fibula : the internal malleolar
is represented proceeding from the other side of the
anterior tibial artery ; 6, the tarsal branch of the dorsal
artery, represented in this instance as larger than usual
and furnishing some of the branches of the next artery ;
7, the metatarsal branch, giving off the dorsal inter-
osseous arteries ; (in the first interosseous space the dorsal
artery of the foot is seen to give off the anastomosing
branch which unites with the deep plantar arch ;) be-
tween 8, and 8, the collateral branches of the dorsal
digital arteries.
interosseous ligament, and is then at a con-
siderable distance from the spine of the tibia ;
but in descending it gradually approaches that
ridge, and towards the lower part of the leg is
supported on the anterior surface of the bone.
Relation to Veins and Nerves. The anterior
tibial artery is accompanied by two veins (vense
comites). The anterior tibial nerve, coming
from the outer side of the head of the fibula,
approaches the artery at some distance below the
place -where the vessel appears in front of the
interosseous ligament. Lower down, the nerve
for the most part lies in front of the artery,
but often changes its position from the one side
of the vessel to the other.
BRANCHES. Besides numerous small muscu-
lar branches, the anterior tibial artery furnishes
the following.
(a) The recurrent artery, given off as soon as
the anterior tibial reaches the front of the leg,
ascends through the fibres of the tibialis anticus,
and, ramifying on the outside and front of the
knee-joint, anastomoses with the inferior articu-
lar and other branches of the popliteal artery.
(6) The malleolar arteries, two in number,
external and internal, are given off near the
ankle-joint, but are very variable in size and
mode of origin. The internal branch passes beneath the tendon of the
I
450 DORSAL ARTERY OF THE FOOT.
tibialis anticus to the inner ankle, and communicates with branches of the
posterior tibial artery. The external branch passes outwards under the
tendon of the common extensor of the toes, and anastomoses with the
anterior division of the peroneal artery, and also with some ascending or
recurrent branches from the tarsal branch of the dorsal artery of the foot.
These malleolar arteries supply articular branches to the neighbouring joints.
DORSAL ARTERY OF THE FOOT.
The dorsal artery of the foot (dorsalis pedis), the continuation of the
anterior tibial artery, extends from the termination of that vessel at the
bend of the ankle, to the posterior end of the first metatarsal space. At
this spot it divides into two branches, of which one proceeds forwards in the
first interosseous space, whilst the other dips into the sole of the foot, and
terminates by inosculating with the plantar arch. The dorsal artery of the
foot lies in the interval between the tendon of the proper extensor of the
great toe, and that of the long extensor of the other toes ; and is covered
by a deep layer of fascia, which binds it to the parts beneath. Near its
end it is crossed by the innermost tendon of the short extensor of the toes.
Two veins accompany this artery ; the anterior tibial nerve lies on its
outer s-ide.
BRANCHES. The principal branches of the dorsal artery of the foot are
directed outwards and forwards upon the tarsus and metatarsus, and are
named accordingly. Some small offsets also run obliquely inwards, and
ramify upon the inner side of the foot.
(a) The tarsal branch arises from the artery usually where it crosses the
scaphoid bone, but its point of origin varies in different instances. It inclines
forwards and outwards upon the tarsal bones covered by the short extensor
muscle of the toes, then, curving backwards towards the cuboid bone,
divides into branches which take different directions over the tarsus.
The branches supply the extensor brevis digitorum muscle and the tarsal
joints, and anastomose with the external plantar, the metatarsal, the
external malleolar, and the peroneal arteries.
(6) The metatarsal artery arises farther forwards than the preceding
vessel, and is directed outwards, like it, beneath the short extensor muscle.
Sometimes there are two metatarsal arteries, the second being of smaller
size; and not unfrequently, when there is but a single vessel of this name,
it arises in common with the tarsal artery. Its direction is necessarily in-
fluenced by these circumstances ; being oblique when it arises far back, and
almost transverse when its origin is situated farther forwards than usual.
It anastomoses with the tarsal and external plantar arteries, and gives off
iuterosseous branches.
The three interosseous branches from the metatarsal artery are small straight
vessels which pass forwards along the three outer interosseous spaces, resting upon
the dorsal interosseous muscles. Somewhat behind the clefts between the toes each
divides into two branches, which run forward along the contiguous borders of the
corresponding toes, forming their dorsal collateral branches. Moreover, from the
outermost of these interosseous arteries a small branch is given off, which gains the
outer border of the little toe, and forms its external collateral branch. These arteries
communicate with the plantar arch opposite the fore part of the interosseous spaces, by
means of the anterior perforating branches, and at the back part of the interosseous
spaces, by the posterior perforating branches.
BRANCHES OF THE DORSAL ARTERY.
451
(c) The first interosseous branch, or dorsal artery of the great toe, is con-
Fig. 308. ANTERIOR VIEW OP THE ARTERIES OP THE
LEG AND DORSUM OP THE FOOT (from Tiedemann). \
The tibialis anticus muscle is drawn towards the inner
side so as to bring the anterior tibial artery into view,
the extensor proprius pollicis, the long common extensor
of the toes, and the peroneus tertius muscles in their
lower part, and the whole of the extensor communis
brevis, have been removed. 1, external superior articular
branch of the popliteal artery, ramifying on the parts
surrounding the knee ; and anastomosing with the other
articular branches and with 2, the recurrent branch of
the anterior tibial artery ; 3, 3, anterior tibial, giving
off muscular branches on each side ; 4, dorsal artery
of the foot ; 5, external anterior malleolar artery coming
off from the anterior tibial and anastomosing with
the anterior peroneal artery which is seen descending
upon the lower part of the fibula : the internal malleolar
is represented proceeding from the other side of the
anterior tibial artery ; 6, the tarsal branch of the dorsal
artery, represented in this instance as larger than usual
and furnishing some of the branches of the next artery ;
7, the metatarsal branch, giving off the dorsal inter >
osseous arteries ; (in the first interosseous space the
dorsal artery of the foot is seen to give off the anasto-
mosing branch which unites with the deep plantar arch ; )
between 8 and 8, the collateral branches of the dorsal
digital arteries.
Fig. 308.
tinned forwards from the dorsal artery of the
foot at the point where it dips down to the
sole. This branch runs along the outer surface
of the first metatarsal bone, and furnishes the
small dorsal digital vessels of the great toe and
adjacent side of the second toe.
(d) The plantar digital branch of the innermost
space, given off from the dorsal artery between
the heads of the first interosseous muscle, near
the inosculation with the plantar arch, passing
forwards divides into two smaller branches which
proceed along the contiguous sides of the first
and second toe.
(e) The plantar digital branch for the inner
side of the great toe crosses beneath the first
metatarsal bone, and runs along the inner side of
the great toe on its plantar surface.
PECULIARITIES of the anterior tibial artery. Origin.
In cases of early division of the popliteal arter} r , the
place of origin of the anterior tibial is necessarily
higher up than usual, being sometimes found as high
as the bend of the knee-joint. In some of these cases
(the posterior tibial artery being small or wanting),
the anterior tibial is conjoined with the peroneal
artery. When the anterior tibia! arises higher than
usual, the additional upper part of the vessel has been
seen resting on the posterior surface of the popliteus
muscle, and it has been likewise found between that muscle and the bone.
452 TEE VEINS.
Course. The anterior tibial artery, having its usual place of origin, has been
found to deviate outwards towards the margin of the fibula in its course along the
front of the leg, and then to return to its ordinary position beneath the annular
ligament in front of the ankle-joint. This artery has been also noticed by Pelletan
and by Velpeau to approach the surface at the middle of the leg, and to continue
downwards from that point, covered only by the fascia and integument. Yelpeau
states that he found the artery to reach the fore part of the leg by passing round the
outer side of the fibula. (Pelletan, "Clinique Chirurgicale," &c., p. 101 : Paris, 1810.
Velpeau, " Nouveaux Elemens de Medecine Ope"ratoire," &c., t. i., pp. 137 and 537 :
Paris, 1837.)
Size. This vessel more frequently undergoes a diminution than an increase of
size.
It may be defective in various degrees. Thus, the dorsal branch of the foot may
fail to give off digital branches to the great and second toes, which may be then
derived from the internal plantar division of the posterior tibial. In a farther degree
of diminution the anterior tibial ends in front of the ankle or at the lower part of
the leg ; its place being then taken by the anterior division of the peroneal artery,
which supplies the dorsal artery of the foot ; the two vessels (anterior tibial and
anterior peroneal) being either connected together or separate.
Two cases are mentioned by Allan Burns, in which the anterior tibial artery was
altogether wanting, its place in the leg being supplied by perforating branches from
the posterior tibial artery, and on the dorsum of the foot by the anterior division of
the peroneal artery.
The dorsal artery of the foot is occasionally larger than usual ; in that case com-
pensating for a defective condition of the plantar branch from the posterior tibial
artery.
This artery has been repeatedly found to be curved outwards between its com-
mencement at the lower border of the annular ligament and its termination in the
first interosseous space.
VEINS.
The systemic veins commence by small branches which receive the blood
from the capillaries throughout the body, and unite to form fewer and
larger vessels, which end at last by pouring their contents into the right
auricle of the heart through two large venous trunks, the superior and in-
ferior venae cavse. The blood which nourishes the substance of the heart
itself, is returned by the coronary or cardiac veins to the same auricle.
The veins, however, which bring back the blood from the stomach,
intestines, spleen and pancreas, have an exceptional destination ; not convey-
ing the blood directly to the heart, but joining to form a single trunk the
portal vein, which ramifies after the manner of an artery in the substance
of the liver, and carries the blood within it to the capillaries of that organ.
From these the blood passes into the ultimate twigs of the hepatic veins,
and is conveyed by these veins into the inferior vena cava. The veins thus
passing to the liver constitute the portal system.
The anastomoses of veins are much larger and more numerous than those
of arteries. The veins of many parts of the body consist of a subcutaneous
and a deep set, which have very frequent communications with each other.
In some parts of the body, chiefly the limbs and surface, the veins are
provided with valves, whilst in others no valves exist.
The systemic veins are naturally divisible into two groups : firstly, those
from which the blood is carried to the heart by the superior vena cava, viz.,
the veins of the head and neck and upper limbs, together with those of the
spine and a part of the walls of the thorax and abdomen, with which may
be associated also the veins of the heart ; and secondly, those from which
BRACniO-CEPHALIC VEINS. 453
the blood is carried to the heart by the inferior vena cava, viz., the veins
of the lower limbs, the lower part of the trunk, and the abdominal
viscera. (For a general representation of the venous system, see fig. 224 at
p. 298.)
UPPER VENA CAVA.
The upper vena cava conveys to the heart the blood which is returned
from the head, the neck, the upper limbs, and the thorax. It is formed by
the union of the right and left brachio-cephalic veins. It extends from a
little below the cartilage of the first rib on the right side of the sternum to
the base of the heart, where it opens into the right auricle. Its course is
slightly curved, the convexity of the curve being turned to the right side.
It has no valves. At about an inch and a half above its termination, it is
invested by the fibrous layer of the pericardium, the serous membrane
being reflected over it. The upper cava lies immediately in front of the
right pulmonary vessels, and between the right lung and the aorta, which
partly overlap it. It receives several small veins from the pericardium and
the mediastinum ; and lastly, it is joined by the right azygos vein, imme-
diately above the place where it becomes invested by the pericardium.
PECULIARITY. In several instances, the two innominate veins, which usually join
to form the vena cava superior, have been seen to open separately into the right
auricle. This peculiarity is explained by reference to the development of the parts,
and will be more fully referred to at p. 485, in connection with the description of the
great cardiac vein.
INNOMINATE OR BRACHTO-CEPHALIC VEINS.
The blood returned from the upper limbs through the subclavian veins,
and from the head and neck by the jugular veins, is poured into two trunks,
named the brachio-cephalic or innominate veins. These vessels, resulting
from the union of the subclavian with the internal jugular vein at each side,
commence opposite the inner ends of the clavicles, and terminate a little
below the cartilage of the first rib on the right side, where, by uniting, they
form the upper vena cava. The right vein is very short, and nearly vertical
in its direction ; it is in apposition, on the right side, with the pleura and
the upper part of the right lung. The vein of the left side, about three
times longer than the right vein, pursues a course from left to right, at
the same time inclining somewhat downwards : it crosses behind the upper
part of the first bone of the sternum, separated from it by the sterno-
hyoid and sterno-thyroid muscles, and by the thymus gland or its remains ;
it lies in front of the three primary branches given off from the arch of the
aorta, and rests upon the highest part of the arch. The innominate veins
have no valves.
LATERAL TRIBUTARIES. (a) The inferior thyroid veins emerge from a
venous plexus situated on the thyroid body those of opposite sides commu-
nicating by small branches across the trachea. The vein of the left side
descends in front of the trachea, behind the sterno-thyroid muscles, and
ends in the left brachio-cephalic or innominate vein : that of the right side
inclines outwards in some degree, and opens into the corresponding brachio-
cephalic vein, or into the angle of union between it and the vessel of the
opposite side.
(6) The internal mammary veins follow exactly the course of the arteries
of the same name two veins accompanying each of the arteries. The
two companion veins of the artery arise by small branches, derived from
464 UPPER VENA CAVA.
the fore part of the walls of the abdomen, where they anastomose with
Fig. 309.
Fig. 309. SKETCH OP THE PRINCIPAL VENOUS
TRCNKS, TOGETHER WITH THE THORACIC DUCT. ^
a, the basilar process of the occipital bone,
through which and the temporal bones a trans-
verse incision has been made so as to lay open the
jugular foramen on both sides ; b, the body of the
fifth cervical vertebra ; c, the first rib ; tZ, the
sixth ; e, the twelfth ; /, the body of the fifth
lumbar vertebra ; 1, trunk of the vena cava supe-
rior divided at the place of its entrance into the
right auricle ; 2, right, 2', left subclavian veins ;
3, right internal jugular vein ; the left is cut
short immediately above the place where it joins
the subclavian vein. ; 3', 3', lower part of the
lateral sinuses of the dura inater ; that of the left
side is divided inferiorly ; that of the right side
shows at its junction with the jugular vein the
bulb which lies in the jugular depression of the
temporal bone ; 4, right, and 4', left external
jugular veins ; 5, right, and 5', left vertebral veins
anastomosing with 5", external vertebral viens,
before joining the subclavian veins ; 6, placed on
left subclaviau vein below the opening of the last,
and of the thoracic duct ; below b, the inferior thy-
roid veins ; 7, 7', the internal mammary veins; 8,
the left superior intercostal vein joining the left
brachio-cephalic vein, and anastomosing below
with intercostal veins which join the trunk of the
azygos ; the right superior intercostal vein is seen
joining the azygos vein; 9, main or right azygos vein ;
the uppermost figure points to the curved portion,
which passes over the right bronchus before joining
the vena cava superior ; 9', the left azygos, repre-
sented here as crossing the vertebral column on the
eighth vertebra; 10, the thoracic duct; the upper
figure is on the fourth dorsal vertebra, the lower
on the first lumbar close to the receptaculum chyli;
11, trunk of the inferior vena cava divided below
the liver ; the figure is immediately over the place
of origin of the renal veins ; below it is seen
dividing on the fourth lumbar vertebra into the
two common iliac veins ; 12, the union of the left
azygos vein with the left renal vein ; 13, on the
right side, the commencement of the right azygos
vein in the lumbar region, joined by several lumbar
veins; 13', the commencement of the azygos vein
of the left side, joining similar veins on that side ;
14, 14', the external iliac veins ; 15, placed on
the promontory of the sacrum, points on either
side to the prolongation of the lower branches of
the right and left lumbar veins into the pelvis, and
their union with sacral and other branches of the
internal iliac veins.
the epigastric veins ; thence proceeding
upwards between the cartilages of the ribs
and the pleura, they receive the anterior
intercostal veins which correspond with the
branches of the internal mammary artery,
together with some small diaphragmatic, thymic and mediastinal veins, and,
FACIAL VEIN. 455
these finally uniting into a single trunk, each vein terminates in the brachio-
cephalic of its own side.
(c) The superior intercostal veins. The right superior intercostal vein
receives the blood from the first or the first two or three spaces, communicating
with the vessel in the space next below, and opens into the innominate trunk
of the same side, or into the vena cava. Frequently the veins at the right
side, corresponding with the superior intercostal artery, pass downwards
separately, to open into the azygos vein, as that vessel arches forwards to
join the upper vena cava : the separate vein thus formed is inferior in
size to that on the left side. The left superior intercostal vein varies in
length in different persons, being small when the azygos minor is large, and
vice versa. Usually it receives the veins from the three or four upper spaces,
and is then directed forwards over the left side of the spinal column and
the aorta to open into the left innominate vein. It receives in its course
the left bronchial vein. The left vein is sometimes directed downwards to
join an azygos vein on its own side.
VEINS OF THE FACE, NECK, AND HEAD.
The blood returning from the head and neck flows on each side into two
principal veins, the external and internal jugular. The veins of the head
and neck have generally no valves. The external jugular vein is provided
with a valve at its entrance into the subclavian vein, and in most cases with
another about the middle of its course : and the internal jugular is also
furnished with valves near its junction with the subclavian. These valves,
however, are not efficient in stopping the regurgitation of the blood, or the
passage of injections from below upwards.
The veins on the exterior of the cranium and face converge and unite, so
as to form two trunks, the facial and the temporal veins.
THE FACIAL VEIN.
The facial vein lies obliquely along the side of the face, extending from
the inner margin of the orbit downwards and outwards to the anterior
border of the masseter muscle. Resting on the same plane as the facial
artery, but farther back, and less tortuous, it has very nearly the same
relations to contiguous parts. It commences at the side of the root of the
nose by a vein formed by the junction of branches from the forehead, eye-
brow, and nose, and increases by receiving others during its course. Below
the jaw it inclines outwards and backwards, covered by the cervical fascia
and the platysma muscle ; and soon unites with a large branch of commu-
nication derived from the temporal vein, to form the temporo-maxillary or
common facial vein, a short vessel of considerable size, which joins obliquely
the trunk of the internal jugular.
TRIBUTARIES. (a) The frontal vein commences on the roof of the skull by
branches, which descend obliquely inwards upon the forehead, maintaining communi-
cations in their course with the anterior branches of the temporal vein. It descends
vertically, parallel with the corresponding vessel of the opposite side, with which it is
connected by transverse branches, and ends in the angular vein. In some instances
the veins of the two sides unite and form a short trunk, which again divides into
two branches at the root of the nose. As it descends from the forehead, the frontal
vein receives a branch from the eyebrow, and some, of smaller size, from the nose and
upper eyelid.
456
VEINS OF THE HEAD AND NECK.
(&) The supraorbital vein (v. supercilii) runs inwards in the direction of
the eyebrow, covered by the occipito-frontalis muscle. Its branches are con-
nected externally with those of the external palpebral and superficial temporal
veins ; in its course it receives branches from the contiguous muscles and integu-
ment, and at the inner angle of the orbit inclines downwards to terminate in the
frontal vein.
Fig. 310. Fig. 310. VIEW OP THE SU-
PERFICIAL VEINS OF THE
HEAD AND NECK.
1, sterno-mastoid muscle ; a,
facial vein ; b, temporal vein ;
c, transverse facial ; d, pos-
terior auricular ; e, internal
maxillary vein ; /, external
jugular vein ; g, posterior ex-
ternal jugular ; h, anterior
jugular ; i, posterior scapular
and suprascapular veins ; k,
internal jugular vein; I, occi-
pital veins ; m, subclavian vein :
above the inner side of the orbit
are shown the frontal and su-
praorbital veins, and their de-
scending branches to anastomose
with the angular or terminal
branch of the facial vein.
(c) The angular vein, formed
by the junction of the supra-
orbital and frontal veins, is
perceptible beneath the skin as
it runs obliquely downwards
and outwards near the inner
margin of the orbit, resting
against the side of the nose at
its root. This vessel receives on the inner side the nasal veins, which pass upwards
obliquely to join it from the side and ridge of the nose ; whilst some small superior
palpebral veins open into it from the opposite direction. On a level with the lower
margin of the orbit it becomes continuous with the facial vein.
(d) The inferior palpebral veins, two or three in number, are derived from the
lower eyelid, from the outer side of the orbit, and from the cheek. They pass in a
direction obliquely inwards above the zygomatic muscle, and then turn beneath it
previously to their termination.
(e) Communicating branches from the pterygoid plexus (deep facial, anterior, inter-
nal maxillary) ; and also some branches proceeding from the orbit, furnished by the
infraorbital of the internal maxillary vein, join the facial on a level with the angle
of the mouth.
(/) Labial, buccal, masseteric, and mental branches join the facial below the angle
of the mouth.
(g) The ranine vein, a small vessel which lies along the under surface of the tongue,
close to the frsenum linguae, is in apposition with the artery of the same name ; its
course is backwards and outwards, between the mylo-hyoid and hyo-glossus muscles,
to open into the facial vein, or sometimes into the lingual.
(h) The submental vein, larger than the preceding, commences below the chin ; it
receives branches from the subrnaxillary gland, and from the mylo-hyoid muscle, and,
keeping close under cover of the margin of the jaw-bone, joins the facial vein ; but
in some instances it enters the lingual or superior thyroid vein.
(i) Submaxillary branches from the gland join the facial vein either separately or
united into one trunk.
0") The palatine vein returns the blood from the plexus round the tonsil and
TEMPORAL AND INTERNAL MAXILLARY VEINS. 457
from the soft palate ; it passes downwards, deeply seated by the side of the pharynx,
to join one of the preceding veins, or terminate in the facial separately.
THE TEMPORAL VEIN.
The temporal vein, a vessel of considerable size, descends in front of the
external auditory tube, reaching from the zygoma, upon which it rests, to
the angle of the jaw. It results from the union of branches which are
spread out upon the side of the head, some superficially, and others deeply
seated. The superficial branches commence upon the arch of the skull,
where they communicate with the ramifications of the frontal and occipital
veins, as well as with those of the corresponding vein of the opposite side.
Descending on the surface of the temporal fascia, they converge ; those
from the fore part inclining a little backwards, while the posterior branches
run forwards over the ear ; and the two sets joining together above the
zygoma form the trunk of the temporal vein. The deeper branches, arising
in the substance of the temporal muscle, unite to form a vein of some size,
called the middle temporal, to distinguish it from branches still more deeply
placed, which open into the internal maxillary vein. The middle tem-
poral vein falls into the common temporal trunk at its commencement above
the zygoma. The temporal vein gradually sinks into the substance of the
parotid gland as it descends behind the ramus of the jaw. Beneath the
angle of that bone, it divides into two vessels, one of which turns backwards,
and forms the commencement of the external jugular vein, while the other
communicates with the facial vein near its termination.
LATERAL TRIBUTARIES. These are numerous: (a) parotid branches from the parotid
gland ; (b) articular, from the articulation of the jaw ; (c) anterior auricular veins
from the external ear ; (d) the transverse facial, a branch of considerable size, corre-
sponding with the transverse facial artery ; (e) the posterior auricular directed for-
wards from behind, and joined by the stylo-mastoid vein ; and (/) the internal
maxillary vein, a large vessel, which requires more particular description.
THE INTERNAL MAXILLARY VEIN.
The internal maxillary vein corresponds somewhat in direction and posi-
tion with the artery of the same name, and receives branches from the
neighbouring parts, most of which are the vense comites of the corresponding
divisions of the internal maxillary artery. Thus three or four deep temporal
branches descend from the temporal muscle ; others come from the pterygoid,
masseter, and buccinator muscles. The middle meningeal veins and some
palatine veins also end in the internal maxillary ; and lastly, branches from
the surface of the upper jaw superior dental, and another, of large size,
from the lower jaw, emerging from the dental foramen inferior dental.
These different branches form a plexus of veins, named pterygoid plexus,
which is placed in the lower part of the temporal fossa, between the tem-
poral and the external pterygoid muscle, and in part between the pterygoid
muscles. It communicates in front with the facial vein, and above, with
the cavernus sinus by branches through the base of' the skull. From this
plexus proceed one or two short trunks, which join nearly at right angles
with the temporal vein.
The FACIAL COMMUNICATING vein, extending between the temporal vein at
the angle of the jaw and the facial vein, a little in front of it, is a short
trunk, usually the larger of the two into which the temporal vein divides,
and placed nearly transversely, so as to allow the flow of blood either from
458
VEINS OF THE HEAD AND NECK.
the temporal into the internal jugular vein, or from the facial into the
external jugular.
Fte. 811.
Fig. 311. DIAGRAMMATIC VIEW OP THE SINUSES OP THE DURA MATER AND SOME OP THE
DEEP VEINS OF THE NECK AND HEAD (modified from Cloquet and other sources). ^
The greater part of the calvariurn has been removed ; but an arched strip has been
kept in the fore and upper part of the region of the superior longitudinal sinus. The
occiput has been entirely removed so as to expose the lateral sinus and its termination in
the jugular vein. a, the falx cerebri ; b, the tentorium cerebelli of the right side ; c,
zygomatic arch ; d, malar bone ; e, angle of the jaw ; /, spiuous process of the axis
vertebra; 1, superior longitudinal sinus; 2, inferior longitudinal sinus; 2, 3, straight
sinus ; 2', internal veins of the brain (veins of Galen) ; 3, lateral sinus, descending to
4, the commencement of the internal jugular ; 3', superior petrosal sinus ; 4, 4, the
internal jugular vein ; 5, 5, superficial temporal vein, leading into the external jugular
vein ; 6, middle temporal ; 7, posterior auricular ; 8, internal maxillary ; 8', pterygoid
plexus and communications with the deep temporal veins ; 9, communicating branch
between the facial, temporal and external jugular ; 9', pharyngeal branches ; 10, facial
vein; 10', submental branch; 10", continuation of the facial into the angular; 11, an
occasional branch from the neck ; 12, vertebral vein and artery ; 13, external spinal
veins forming a plexus over the vertebral arches; 14, occipital sinus communicating
above the atlas with the spinal plexus.
EXTERNAL AXV IXTERXAL JUGULAR VEINS. 459
THE EXTERNAL JUGULAR VEIN.
The external jugular vein commences on a level with the angle of the
lower maxilla, at the end of the temporal vein, and descends perpendicu-
larly between the platysma and fascia, crossing the sterno-mastoid muscle.
In consequence of the oblique direction of that muscle, the vein gets to its
outer border, and continues behind it down to the lower part of the neck,
where it pierces the fascia to terminate either as a single trunk, or by two
or three branches in the subclavian vein. It is provided with a valve at its
lower end, and in most cases with another about the middle of its course.
TRIBUTARIES. The external jugular vein receives some large branches from behind,
and superficial branches from the fore part of the neck. The largest branches are
the following.
(a) The posterior branch, lying at first between the splenius and trapezius muscles,
passes down at the outside of the jugular vein, and below the middle of the neck
opens into that vessel.
(&) The suprascapular and posterior scapular veins, corresponding to the arteries
of the same name, pass transversely inwards to join the external jugular vein close to
its termination.
The anterior jugular vein arises from the convergence of some superficial
branches in the submaxillary region. This vessel lies along the fore part of
the neck, sometimes near the sterno-mastoid muscle, and either terminates
by inclining outwards to join the external jugular vein, or, after giving to it
a branch of communication, sinks beneath the sterno-mastoid muscle, and
ends in the subclavian vein. The lower ends of the two anterior jugular
veins are frequently united by a transverse branch placed behind the sterno-
mastoid muscles and top of the sternum.
The external jugular vein is very variable in size. It is frequently very small, and
may be absent altogether. The anterior jugular vein is likewise very variable.
INTERNAL JUGULAR VEIN.
The internal jugular veins, receiving the blood from the brain and cranial
cavity, are contiguous at their upper extremities with the lateral sinuses
within the cranium, and terminate inferiorly in the innominate or brachio-
cephalic veins. The commencement of each internal jugular vein at the
wide part (jugular fossa) of the foramen jugulare, is somewhat enlarged,
and has been named the sinus or gulf of the internal jugular vein. Beneath
the skull, the vein is supported by the rectus lateralis muscle, and lies close
to the outer side of the internal carotid artery, as far as the cornu of the
os hyoides. It is joined at this point by the common facial vein, and
becomes considerably enlarged ; it then descends parallel with the common
carotid artery, lying at its outer side and enclosed in the same sheath,
together with the vagus nerve. At the root of the neck it joins nearly at a
right angle with the subclavian vein, and so forms the innominate or
brachio-cephalic vein. Close to the lower termination of the jugular, or
from half an inch to an inch above it, is placed a double valve as in other
veins. (Struthers, " Anat. and Phys. Observ.," p. 173.)
TRIBUTARIES. Previously to its junction with the facial vein, the internal jugular
receives the lingual, pharyngeal, and occipital veins ; one or more of which, however,
very frequently end in the common facial trunk.
(a) The lingual vein begins at the side and upper surface of the tongue, and passes
backwards, receiving branches from the sublingual gland; occasionally the ranine
vein joins it, and sometimes also the pharyngeal.
H H 2
460 VEIXS OF THE HEAD AXD NECK.
(i) The pharyngeal vein commences at the back and sides of the pharynx, and
sometimes ends in the superior thyroid vein, and at other times in the lingual, or
separately in the internal jugular vein.
(c) The occipital vein, corresponding in course and distribution with the occipital
artery, communicates with a plexus of veins upon the occiput, and terminates occa-
sionally in the external jugular A^ein, but more frequently in the internal.
(d )The common facial vein has been already described.
(?) The laryngeal vein receives branches from the larynx through the thyro-h} r oid
membrane, and opens into the internal jugular, the common facial, or sometimes into
the superior thyroid vein.
(/) The superior thyroid vein commences by branches in the thyroid body,
in company with those of the superior thyroid artery, and runs transversely
outwards.
(g) The middle thyroid vein, likewise derived from the thyroid body, is placed
lower than the superior thyroid.
VENOUS CIRCULATION WITHIN THE CRANIUM.
The part of the venous system contained within the skull consists of
veins properly so called, and of certain channels called sinuses, which
receive the blood from those veins, and conduct it to the internal jugular
veins. The sinuses alluded to are spaces left between the layers of the
dura mater, the fibrous covering of the brain.
CEREBRAL VEINS.
The veins of the brain are divisible into those which ramify upon its sur-
face, and those which are placed within its ventricles.
The superficial veins upon the upper surface of the hemispheres are for
the most part lodged in the tortuous sulci between the convolutions ; but
some run over the convexity of the convolutions. Their general direction is
towards the middle line ; and, on reaching the margin of the longitudinal
fissure between the hemispheres, they receive branches from the flat mesial
surface of the hemispheres, and, becoming invested by tubular sheaths of
the arachnoid membrane, incline obliquely forwards and open in that
direction into the superior longitudinal sinus.
The veins upon the sides and under surface of the brain are directed
outwards, to open into the lateral and other sinuses at each side.
The deep veins of the brain commence by branches within the ventricles
of that organ. Upon the surface of the corpus striatum, for example,
several small venous branches are seen, which for the most part converge
to form a slender vein which runs along the groove between the corpus
striatum and optic thalamus, and opens into one of the veins of the choroid
plexus. The minute veins of the choroid plexus pass backwards, and incline
towards the middle line from each side, so as to form, by their union, two
veins vence Galeni. These, lying parallel, run directly backwards, enclosed
within the velum interpositum, and escape from the interior by passing
through the great transverse fissure of the brain between the under surface
of the corpus callosum and the tubercula quadrigemina. In this way they
reach the anterior margin of the tentorium cerebelli, at its place of union
with the falx cerebri, where they terminate by opening into the straight
sinus.
The veins of the cerebellum are disposed in two sets. Those of the
upper surface incline inwards and forwards for the most part, and run
upon the upper vermiform process, over which they ascend a little to reach
the straight sinus, in which they terminate ; some, farther forward, open
INTRACRANIAL VEINS.
461
into the veins of Galen. Those at the under surface run transversely out
wards, and pour their contents into the occipital and the lateral sinuses.
Fig. 312.
Fig. 312. INTERNAL VIEW OP THE BASE OF THE SKULL, SHOWING THE SINUSES OP THE
DURA MATER, &c. ^
The sinuses of the dura mater have been opened, a small portion of the i-oof of the
orbit has been removed posteriorly on the left side, and the dura mater has been dissected
so as to bring into view the arteries at the base of the skull, the venous sinuses and the
issue of the cerebral nerves.
I., the olfactory bulb; II., the optic nerves, that on the left side cut short; III.,
placed on the pituitary body, indicates the third nerve; IV., the trochlear nerve , V.,
placed opposite to the middle of the three divisions of the fifth nerve as they pass out of
the cranium ; VI., the sixth nerve ; VII., the facial and auditory nerves entering the
meatus auditorius internus ; VIIL, placed opposite to the three portions of the eighth pair
as they pass into their several foramina of the dura mater ; IX., the hypoglossal nerve
as it passes to the anterior coadyloid foramen ; 1, the right internal carotid artery as it
makes its turn in the cavernous sinus on the groove of the sphenoid bone ; 2, its ophthal-
mic branch proceeding into the orbit, below and to the outside of the optic nerve ; 3,
division of the basilar artery into the two posterior cerebral arteries, one of which is
represented on the right side as giving off the communicating artery to the internal carotid ;
4, basilar artery ; 5, vertebral arteries giving the anterior spinal ; x , great meningeal
vessels spreading upwards from the foramen spinosum ; 6, superior petrosal sinus ; 7,
inferior petrosal running back into the lower part of the lateral sinus ; 8, termination of
the lateral sinus in the internal jugular vein, and continuation of the lateral sinus ;
8', commencement of the lateral sinus ; 9, occipital sinuses; 10, torcular Herophili, and
below that number in the figure, the superior longitudinal sinus.
CRANIAL SINUSES.
The venous sinuses within the cranial cavity admit of being divided into
462
VEINS OF THE HEAD AND NECK.
two sets, viz., those placed in the prominent folds of the dura mater, and
those situated in the base of the skull.
Fig. 313.
Fig. 313. SKETCH OP THE IN-
TERNAL VEIKS OP THE CKANIDSI
AND NOSE.
a, torcular Herophili ; J, superior
longitudinal sinus of the dura mater ;
c, inferior longitudinal sinus ; d,
straight sinus ; e, internal veins of
the brain, or veins of Galen ; g, occi-
pital sinus ; h, superior petrosal
sinus ; i, inferior petrosal sinus ; k,
nasal veins on the septum ; superiorly
is shown the commencement from
soni3 of these of the superior longi-
tudinal sinus, and lower down some
of the nasal veins passing out by the
spheno-palatine foramen.
The form and size of the
sinuses are various. All of
them are lined by a con-
tinuation of the internal mem-
brane of the veius, the dura mater serving as a substitute for the other coats.
The sinuses which are contained in the several processes or folds of the
dura mater converge to a common point, which corresponds with the internal
occipital protuberance, and is called the confluence of the sinuses, or torcular
Herophili. The form of the torcular is very irregular. Five or six apertures
open into it : viz., one from the longitudinal, and one from the straight
sinus ; two from the right and left lateral sinuses ; and one or two from
the posterior occipital sinuses.
The superior longitudinal sinus (s. falciformis superior), commencing at the
crista galli, extends from before backwards, in the upper border of the falx
eerebri, gradually increasing in size as it proceeds. It is three-sided, and
is crossed obliquely at the inferior angle by several bands, the chordce TFillisii.
The veins from the cerebral surface open into this sinus chiefly towards the
back part ; and in such a way that the apertures of the greater number of
them are directed from behind forwards, contrary to the direction of the
current within it. The longitudinal sinus communicates with the veins on
the outside of the occipital bone, by a branch (one of the "emissary veins,"
Santorini) which passes through a hole in the parietal bone.
The inferior longitudinal sinus (s. falciformis inferior) is very small, and
so much resembles a cylindrical vein, that it is sometimes named inferior
longitudinal vein. Placed in the inferior concave border of the falx cerebri,
it runs from before backwards, and opens into the straight sinus on reaching
the anterior margin of the teiitorium cerebelli. It receives branches from
the surface of the falx cerebri, and sometimes from the flat surface of the
hemispheres.
The straight sinus (s. quartus ; s. tentorii) runs backwards in the base of
the falx cerebri, gradually widening as it approaches the torcular Herophili,
in which it terminates. Besides the inferior longitudinal sinus, the venae
Galeni and the superior veins of the cerebellum open into it.
The lateral sinuses (s. transversi) are of considerable size. Their direc-
tion conforms to that of the groove marked along the inner surface of the
occipital and other bones, and extending from opposite the internal occi-
VENOUS SINUSES OF THE CRANIUM.
463
pital protuberance to the forameu jugulare. The sinus of the right side is
usually larger than that of the left ; both commence at the torcular Hero-
phili, and terminate in the jugular veins. The lateral sinuses receive the
blood transmitted from both the longitudinal sinuses, from the straight and
occipital sinuses, from the veins upon the sides and base of the brain, from
those on the under surface of the cerebellum, and from some of the veins of
the diploe. The petrosal sinuses also join the lateral sinus on each side :
and two emissary veins connect these with the veins at the back of the head
and neck.
Fig. 314. SKETCH OF THE A'ENOUS SINUSKS Fig. 314.
IN THE BASE OP THE CRANIUM, WITH THE
OPHTHALMIC VEIN.
a, sella turcica and circular sinus ; 6,
cavernous sinus receiving c, the ophthalmic
vein ; d, superior petrosal ; e, inferior petrosal
sinus; /, transverse sinus; g, occipital; h,
lateral ; i, termination of the superior longi-
tudinal in the torcular Herophili.
The posterior occipital sinus is some-
times a single canal, not unfrequently
double, as if composed of two com-
partments. It lies along the attached
border of the falx cere belli, extending
from the posterior margin of the fora-
men magnum to the confluence of the
sinuses. It communicates in front
with the posterior spinal plexuses of
veins.
The sinuses placed at the base of the
skull are as follows, taking them in their order from before backwards.
The circular sinus has the form of a ring, and is placed superficially in the
margin of the dura mater round the pituitary body ; it receives the blood
from the minute veins of the pituitary body, and communicates at each side
with the cavernous sinus. Sometimes it is only partially developed, the part
in front of the gland being that usually present : sometimes, however, it is
behind the gland.
The cavernous sinuses, placed one on each side of the body of the sphenoid
bone, over the bases of the great wings, and stretching from the sphenoidal
fissure to the apex of the petrous portion of the temporal bones, are of con-
siderable size, and of very irregular form. Each receives the ophthalmic vein
at its fore part, and communicates internally with the circular sinus, and
posteriorly with the petrosal sinuses. In the wall of each, separated by the
lining membrane from the cavity of the sinus, pass forward the third,
fourth, and sixth cranial nerves, the ophthalmic division of the fifth nerve,
and the internal carotid artery.
The upper petrosal sinus is a narrow canal running along the upper
margin of the petrous part of the temporal bone. Commencing at the back
part of the cavernous sinus, it is directed outwards and backwards in the
attached margin of the teutorium cerebelli ; and, descending a little, ends
in the lateral sinus where this lies upon the temporal bone.
The lower petrosal sinus, wider than the upper, passes downwards and
backwards along the inferior margin of the petrous bone, between this and
464
VEINS OF THE HEAD AND NECK.
the basilar process of the occipital bone. It opens into the lateral sinus
near the termination, or into the internal jugular vein.
The anterior occipital or transverse sinus (sinus basilaris) is placed at the
fore part of the basilar process of the occipital bone, so as to establish a
transverse communication between the opposite inferior petrosal and the
cavernous sinuses.
OPHTHALMIC VEIN.
The ophthalmic vein opens into the cavernous sinus. Its branches are
distributed in the different structures contained within the orbit, in com-
pany with the branches of the ophthalmic artery : some small ramifications
arise from the eyelids, whilst others communicate with the angular branch
of the facial vein ; and those which accompany the supraorbital artery have
similar connections with the veins upon the forehead. All these branches,
together with others arising from the lachrymal gland, from the different
muscles, from the ethmoidal cells, and from the globe of the eye, severally
Fig. 315.
Fig. 315. SKETCH OF THE OPHTHALMIC VEIN, AND OF ITS DISTRIBUTION AND COM-
MUNICATION WITH OTHER VEINS (altered from Hirschfeld arid Leveille).
The orbit is opened from the outer side and the dissection is similar to that for display-
ing the ophthalmic artery (represented in Figure 260, at p. 361) ; a, the optic nerve
before it enters the optic foramen; b, the superior oblique muscle divided before it passes
through its pulley ; c, the lachrymal gland lying upon the eyeball ; d, the insertion of
the inferior oblique muscle ; e, foramen rotundum ; /, sinus maxillaris, opened externally;
I., the ophthalmic vein joining the cavernous sinus ; 1, supraorbital branch ; 2, muscular
and lachrymal branches ; 3, ciliary ; 4, anterior and posterior nasal or ethmoid ; 5,
frontal ; 6, infraorbital ; II., facial vein ; 7, communication with the internal maxillary ;
8, external nasal ; 9, angular, communicating at 10, with the frontal and supraorbital ;
III., external jugular vein commencing at the junction of IV., the temporal and V., the
internal maxillary veins ; 11, meningeal branch ; 12, inferior dental ; 13, muscular ; 14,
communication between the facial, malar, and infraorbital; 15, placed in the spheno-
maxilliary fossa above branches connected with the pterygoid plexus.
VEINS OF THE DIPLOE.
465
named according to the arterial branches which they accompany, join to form
a short single trunk, which leaves the orbit by the inner part of the
sphenoidal fissure, where it is placed between the heads of the external
rectus muscle, and terminates in the cavernous sinus.
Not unfrequently one of the frontal veins is much larger than the others, and,
descending vertically near the middle of the forehead, joins the facial and a branch
of the ophthalmic vein on one side of the root of the nose.
VEINS OF THE DIPLOE.
The veins of the dip!oe of the cranial bones are only to be seen after the
pericranium is detached, and the external table of the skull carefully re-
moved by means of a file. Lodged in canals hollowed in the substance of
the bones, their branches form an irregular network, from which a few
larger vessels issue. These are directed downwards at different parts of the
cranium, and terminate, partly in the veins on the outer surface of the
bones, and partly in the sinuses at the base of the skull.
Fig. 316.
Fig. 316. VEINS OF
THE DlPLOE OF THE
CRANIAL BONES (after
Breschet).
The external table
has been removed from
the greater part of the
calvarium so as to ex-
pose the diploe and the
veins which have been
injected. 1, a single
frontal vein; 2, 3, the
anterior temporal vein
of the right side ; 4,
the posterior temporal ;
5, the occipital vein of
the diploe.
According to Bres-
chet there are four
such veins on each
half of the cranium,
viz., a frontal, occipital, and two temporal.
The frontal is small, and issues by an aperture at the supraorbital notch to join
the vein in that situation. There is often only one frontal vein present.
The temporal are distinguished as anterior and posterior. The anterior is con-
tained chiefly in the frontal bone, but may extend also into the parietal, and opens
into the temporal vein, after escaping by an aperture in the great wing of the sphe-
noid. The posterior ramifies in the parietal bone, and passes through an aperture at
the lower and hinder angle of that bone to the lateral sinus.
The occipital is the largest of all ; and leaves the occipital bone opposite the infe-
rior curved line to open, either internally or externally, into the occipital sinus or
the occipital vein. Its ramifications are confined especially to the occipital bone.
VEINS OF THE UPPER LIMB.
The veins of the upper limb are divisible into two sets, the superficial,
and the deep-seated. Both sets are provided with valves, and these are
466
VEINS OF THE UPPEll LIMB.
more numerous in the deep than in the subcutaneous veins. Valves :vre
constantly to be found at the entrance of branches into the main vessels.
SUPERFICIAL VEINS OF THE UPPER LIMB.
The superficial veins of the upper limb are much larger than the deep ;
they lie between the skin and the fascia. At the upper pait of the fore
Fig. 317. Fig. 317. SKETCH OP THE SUPERFICIAL VEINS OP THE AKM
AND FOREARM FROM BEFORE.
^"\ 1, biceps muscle ; a, radial veins ; b, cephalic veiu ; c, uluar
veins ; d, some of the posterior ulnav veins ; e, basilic veiu
dipping below the fascia ; /, median vein ; g t median basilic ;
h, median cephalic.
arm they are most frequently collected into three
trunks, the radial, ulnar, and median veins. At the
bend of the elbow the median vein divides into an
outer and an inner vessel, named respectively median
cephalic and median basilic, one of which joins with
the radial to form the cep/uzZic vein, while the other
joins with the ulnar to form the basilic. The two
principal cutaneous veins of the forearm, the radial
and the ulnar, commence on the dorsal surface of the
hand, by a sort of plexus, formed by the convergence
of numerous small veins, which proceed from the dorsal
surface of the fingers.
The radial cutaneous vein commences by branches
upon the dorsal surface of the thumb and fore finger.
These ascend over the outer border of the wrist, and
form by their union a large vessel, which passes along
the radial border of the forearm, receiving numerous
branches from the anterior and posterior surfaces-'.
At the bend of the arm, in the groove external to
the biceps muscle, it unites with the median cephalic
division of the median vein, to form the cephalic
vein.
The cephalic vein ascends along the outer border
of the biceps muscle and in the interval between the
great pectoral and deltoid muscles, and finally, dipping
in between those muscles, terminates iu the axillary
vein, between the coracoid process and the clavicle.
The ulnar cutaneous veins are two in number, one on the front, the other
on the back part of the forearm. The posterior ulnar cutaneous vein,
begins on the back of the hand by branches, which unite to form a veiu
placed over the fourth metacarpal space, and called by some of the older
anatomists "vena salvatella." This proceeds along the ulnar border of the
forearm on the posterior aspect, and, below the bend of the elbow, turns
forwards to join with the anterior ulnar cutaneous vein, which ascends from
the anterior surface of the wrist. At the bend of the elbow, the common
ulnar cutaneous unites with the median basilic division of the median to
form the basilic vein.
The basilic vein, usually of considerable size, ascending along the inner
border of the biceps muscle, iu front of the brachial artery, passes through
SUPERFICIAL AND DEEP VEINS OF THE ARM.
467
the fascia below the middle of the arm, and finally unites with one of the
venae comites of that vessel, or with the axillary vein, which it chiefly
forms.
Fig. 318. VIEW OF THE SUPERFICIAL VEIKS AT Pig - 3]^
THE BEND OF THE AlvM (from E. Qliaill). ^
The full description of this figure will be found
at p. 383. The following numbers indicate the
veins : At 1 and 2, the fascia is opened in front
of a part of the bracbial artery and its accom-
panying veins ; the inner vena comes, marked 1,
has been divided, the outer marked 2, is entire ;
+ , the median nerve; 3, the basilic vein ; 3', the
ulnar veins ; 4, the cephalic vein; 4', one of the
radial veins ; 5, tbe median vein ; 5 to 4', median
cephalic ; 5 to 3', median basilic.
The median cutaneous vein results from
the union, on the anterior part of the fore-
arm, of several branches. It is a short
trunk of variable length, which ascends
between the ulnar and radial cutaneous
veins on the front of the forearm, and
terminates beneath tbe hollow in front
of the elbow by dividing into the median
basilic and median cephalic branches, which
diverge upwards from each other. Close
to its bifurcation it receives a short
branch, the deep median vein, which
pierces the fascia to meet it, and forms a
communication between it and the deep
veins accompanying the arteries.
The median basilic vein, inclining in-
wards to join the basilic vein, passes in
front of the brachial artery, from which it is separated by the fibrous
expansion given by the tendon of the biceps muscle to the fascia covering
the flexor muscles ; it is crossed by branches of the internal cutaneous
nerve.
The median cephalic vein, directed outwards, unites with the cephalic
vein. Branches of the external cutaneous nerve descend behind it.
DEEP VEINS OF THE UPPER LIMB.
The brachial artery and its various branches in the arm, forearm, and
hand, are each accompauied by two veins, named vence comites. These
companion veins lie one on each side of the corresponding artery, and are
connected with each other at intervals by short cross branches, which in
some places surround the artery. Their distribution so closely corresponds
with that of the arteries that they need not be more particularly described.
The brachial veins, or companion veins of the brachial artery, terminate at
the lower margin of the subscapularis muscle by joining the axillary vein ;
not unfrequently, however, one of them will be found to come forward
and unite with the basilic, which soon after becomes continuous with the
axillary vein.
Between the several veins of the upper limb numerous communications
468
VEIN'S OF THE UPPER LIMB.
exist in their whole course. Thus, those which lie beneath the integument
are connected to each other by branches in the hand and forearm. The
veins in each pair of vense comites are also united by short transverse
vessels crossing the artery which they accompany, whilst between those
attending different arteries frequent connections exist. Lastly, the sub-
cutaneous and the deep veins communicate freely, especially in the neigh-
bourhood of joints. This general anastomosis ensures the continuance of
the circulation during muscular action in the frequent and varied motions
of the limb.
AXILLARY VEIN.
The axillary vein returns all the blood from the upper limb : its size is
very considerable, and it is the highest of the veins of the upper limb in
which valves are constantly found. It extends, like the corresponding
artery, from the lower border of the axilla to the outer margin of the first
rib ; it is covered by the pectoral muscles and the costo-coracoid membrane,
and is placed to the inner side of the axillary artery. It is continuous
below with the basilic vein of the arm, either alone or in conjunction with
one of the deep brachial veins.
Fig. 319.
Fig. 319. VIEW OP THE BLOODVESSELS OF THE RIGHT AXILLA AND ARM FROM THE
INNER SIDE (from R. Quain).
The detailed description of this figure will be found at p. 382. The following numbers
indicate the principal veins : 2, the axillary vein ; 3, basilic vein; 3', median basilic ;
4, 4', cephalic vein joining the acromial thoracic and axillary ; 6, alar thoracic and
subscapular ; 7, one of the brachial veins.
TRIBUTARIES. The axillary vein receives the subcutaneous veins of the
arm, viz. the basilic at its commencement, the cephalic towards its termination ;
and between these the companion veins of the brachial artery ; it is also
joined by the several veins corresponding with the branches of the axillary
STJBCLAYIAN YEIX. AZYGOS. 469
artery, viz., the two circumflex and the subscapular veins from the shoulder,
the alar vein from the axilla, and the inferior, superior, and acromial
thoracic veins from the side of the chest.
SUBCLAVIAN VEIN;
The subclavian vein is the continuation of the axillary, but is not like it
constantly provided with valves, although a pair may often be found near
its termination (Struthers, loc. cit.). It extends from the outer margin of
the first rib to the inner end of the clavicle, behind which it terminates by
joining with the internal jugular vein to form the innominate or brachio-
cephalic vein. The subclavian vein crosses over the first rib and behind the
clavicle, not reaching so high up in the neck as the subclavian artery; it is
covered by the clavicle, and by the subclavius and sterno-mastoid muscles,
and lies on a plane anterior to the artery, from which, while resting on
the rib, it is separated by the scalenus anticus muscle and the phrenic
nerve.
TRIBUTARIES. (a). The external and anterior jugular veins (p. 459)
open into the subclavian vein on the outer side of the scalenus anticus
muscle.
(6). The vertebral vein, commencing in branches which proceed from the
pericranium and the deep muscles lying behind the foramen magnum of the
occipital bone, passes outwards and downwards to reach the intertrans verse
foramen of the atlas. Through this foramen, and through the canal formed
by the corresponding foramina of the other cervical vertebrae, the vein
descends with the vertebral artery. Emerging at the foramen in the sixth
vertebra, it runs forwards and downwards to join the subclavian vein close
to the termination : a small branch sometimes descends through the foramen
in the seventh vertebra, and opens separately into the subclavian. The
vertebral vein is joined in its course by several branches from the neigh-
bouring muscles ; also, immediately before its termination, by a branch
corresponding with the deep cervical artery; and in the same situation by
another branch of considerable size, which descends in front of the bodies
and transverse processes of the vertebrae of the neck, and may be termed
the external vertebral vein. It communicates frequently with the spinal
veins in the neck, both those on the outer side, and those in the interior of
the spinal canal.
AZYGOS VEINS.
The azygos veins are longitudinal vessels formed by the union of the
veins corresponding to the arteries of the intercostal spaces, and are placed
on the sides of the spine. In the lower part of the thorax the two veins of
opposite sides are disposed symmetrically, but higher up the blood gathered
from some of the veins of the left side is poured into the trunk on the
right, which becomes enlarged and unsymmetrical, and has on that account
received the name of azygos, while the united lower veins from the corre-
sponding parts on the left side constitute the small or left azygos.
The azygos, or right azygos vein (vena sine pari), commences sometimes
by a small branch derived from the inferior cava, where that vessel turns
forwards to reach its opening in the diaphragm ; but much more frequently
it begins below from the lumbar veins (ascending lumbar) of the right side,
and sometimes from the renal vein. Passing from the abdomen into the
thorax through the aortic opening in the diaphragm, or to the outer side of
470
VEINS OF THE TRUXK.
that opening through the fibres of the diaphragm, the azygos vein ascends
Fig. 320. Fig. 320. SKETCH OP THE PRINCIPAL SYSTEMIC
VENOUS TRUNKS, THE AZYGOS, AND INTERCOSTAL
VEINS.
For the detailed description of this figure see
p. 454. The following indications relate to the
accompanying part of the text : 8, the right, 8',
the left, superior intercostal veins ; 9, the main
trunk of the azygos vein; the uppermost number
ri marks its junction with the superior cava, the
\'~5 a . lowest its passage into the abdomen ; 9', the left or
hemiazgyos ; 10, thoracic duct; 11, inferior vena
cava ; 12, the union of a branch of the left azygos
with the left renal vein; 13, 13', the right and
left azygos veins continued down into the abdomen,
and joining some of the lumbar veins; 15, union
of lumbar, ilio-luinbar, and sacral veins.
on the bodies of the dorsal vertebrse, until
it arrives opposite the root of the right
lung, over which it arches forwards, and
then opens into the upper vena cava, im-
mediately above the point at which that
vessel is invested by the pericardium.
When passing through the opening in the
diaphragm, this vein is accompanied by the
thoracic duct, both being situated on the
right side of- the aorta. In the thorax,
maintaining the same position with respect
to the duct and the oesophagus, it passes in
front of the intercostal arteries 1 , and is
covered by the pleura. It is joined by
the several veins which accompany the
aortic intercostal arteries of the right side ;
and, at about the sixth or seventh dorsal
vertebra, by the left or smaller azygos
vein. It is also joined by several oesopha-
geal and other small veins, and near its
termination by the bronchial vein of the
right lung ; and it is generally connected
with the right superior intercostal vein.
As it communicates below with the vena
cava inferior through one of the branches
of that large vein, while it terminates above
in the vena cava superior, it forms a con-
nection between those two vessels. A few
valves of imperfect formation have been
found in the azygos vein ; its branches
(intercostal veins) are provided with distinct
valves.
On the left side of the chest the veins
of the three or four upper intercostal
spaces are usually united into one trunk,
forming the left superior intercostal vein, which (as already mentioned at
AZYGOS AXD SriXAL VEINS. 471
p. 455) is mcst frequently united with the left innominate vein, bnt some-
times is connected with the main azygos vein.
Of the remaining left intercostal veins, one or two, generally about the
fifth and sixth, pass directly into the azygos ; while the lowest in greater
number unite almost constantly into one trunk, forming the left or small
azygos, which crosses to join the main azygos in the neighbourhood of the
seventh dorsal vertebra. There is frequently union between these three
sets of veins or their intercostal branches, so that a part of one may be
replaced by another, and the relative size of the veins may be subject to
considerable variation.
The left lower or small azygos vein (vena hemiazygos) commences from
on a of the lumbar veins (ascending lumbar), or from the left renal vein, and,
having entered the thorax with the aorta, or through the crus of the
diaphragm, ascends upon the spins in front of the left intercostal arteries,
receiving the lower intercostal veins of the left side ; and passing behind the
aorta, it opens into the right azygos vein, opposite the sixth or seventh
dorsal vertebra.
The azygos vein has been seen to receive the lower vena cava, and, in such cases, is
of course extremely large.
In one instance, Meckel found the azygos ending in the subclavian vein.
All the intercostal veins of the left side have been observed in some instances to
join a single vein, which ended in the left innominate ; the arrangement corresponding
with that on the right side of the body.
The bronchial veins return the blood employed in the nutrition of the
lungs. Their course corresponds with that of the bronchi, which suppott
them as they pass towards the root of the lungs. The bronchial vein of the
right side opens into the trunk of the azygos vein near its termination, that
of the opposite side ends in the superior intercostal vein.
VEINS OF THE SPINE.
The spinal veins form plexuses of closely anastomosing vessels along the
whole length of the spinal column. They have no valves.
The veins within and upon the spinal column may be distinguished into
the following sets : a. The dorsal, placed deeply in the veitebral grooves,
and resting upon the spines and arches of the vertebrae : 6. The veins
lodged within the bodies of the vertebrae : c. The anterior longitudinal,
two long series of veins, or rather venous plexuses, extend behind the
bodies of the vertebrae in the whole length of the canal : d. The posterior
longitudinal veins, situated within the canal on the fore part of the
arches of the vertebras : e. The veins of the spinal cord. There are like-
wise branches of communication, some of which connect all the other sets
together, and some which bring them into connection with the general
venous system. (Breschet, " Essai sur les Veines du Rachis," 4to. ;
" Traite' Anatomique sur le Systeme Veineux," fol., 1829 ; Cloquet,
" Traite d'Anatomie descriptive," <fec.)
a. The dorsal veins. The Wood from the muscles and integument alcrig
the back of the spine is returned by a series of short veins, which ramify
upon the arches and spinous processes of the vertebrae. They run forwards
close to the spinous proctsses, and on reaching the interval between the
arches of the vertebrae, pierce the ligamenta subflava, and terminate in a
venous plexus within the canal. Towards the outer part of the interverte-
bral grooves other veins arise, which pass obliquely forwards, through the
in tertrans verse spaces, in company with the posterior branches of the lumbar
472
VEINS OF THE TRUNK.
and intercostal arteries, and open into the veins which acompany those
vessels.
6. The veins belonging to the bodies of the vcrtebrce (vense basis verte-
brarum, Dupuytren) are comparatively large vessels contained in the
canals within the bodies of the vertebrae ; the arteries which accompany
them being very small. They anastomose on the front of the bones with
some of the superficial veins ; and the trunk of each, having reached the
spinal canal through the foramen in the posterior surface of the body of the
vertebra, divides into two branches, which diverge and terminate in the
large spinal veins behind the bodies of the vertebrae.
c. The anterior longitudinal spinal veins. The blood collected by the
different vessels here described is poured into two large veins, or rather
tortuous venous canals, which extend, one on each side, along the whole
length of the spinal canal behind the bodies of the vertebrae. These
vessels (the great spinal veins of Breschet) are alternately constricted and
enlarged, the constricted points corresponding with the intervertebral
foramina, where they are drawn forwards, and bound down by the branches
of communication which pass outwards. In some parts the veins are double,
or even triple, so as to form a plexus, and occasionally they are altogether
interrupted. In the thoracic region their communicating branches open
into the intercostal veins, in the loins into the lumbar veins, in the neck
for the most part into the vertebral.
Fig. 32]. Fig. 321, A and B. HORIZONTAL AND VERTICAL
SECTIONS OP THE LOWER DORSAL VERTEBRAE,
SHOWING THE EXTERNAL AND INTERNAL VEINS
OF THE SPINE (after Breschet). f
a, spinons process; b, transverse process; c,
body; d, spinal canal; 1, anterior external veins
of the body; 2, posterior external veins of the
vertebral column communicating with the internal
and forming a plexus over the laminae and pro-
cesses ; 3, the posterior, and 4, the anterior in-
ternal plexus of veins of the vertebral canal ; 5,
the internal veins of the body joining the internal
spinal veins ; 6, the lateral veins, which are joined
by the internal and external spinal veins, and
themselves unite with the intercostal.
d, The posterior longitudinal spinal veins
are a complex interlacement of tortuous
veins along the inner or anterior surface
of the arches of the vertebrae. In the
lower part of the canal this interlacement
of veins is not so close as in the upper
portion, where it usually conceals (if the
injection has been successful) the whole
surface of the dura mater. These veins
converge to the intervertebral foramina,
and join by rather small vessels with the
intercostal veins.
e - The veins of the spinal cord (Breschet) ramify upon the cord and its
nerves, enclosed within the sheath formed by the dura mater. Though
they communicate with the other spinal veins, they are not injected with
them, even when the injecting process is most successful. Yery small,
LOWER VEXA CAY A. 473
long, and tortuous, they run upon both, surfaces of the cord, and form a
diffused network. They become larger, for the most part, as they ascend,
but near the base of the skull they are smaller than in the lumbar region.
They communicate freely with the spinal veins and plexuses, by means of
branches which accompany the nerves towards the inter vertebral foramina.
Near the base of the skull they unite to form two or three small trunks,
which communicate by transverse branches with the vertebral veins, and
terminate in the inferior cerebellar veins, or in the petrosal sinuses.
From a consideration of the connection and arrangement of the different
parts of these complex veins, it would appear that the main currents of the
blood in each part flow through them horizontally. The dorsal veins pour
their blood into the longitudinal plexus on the inner surface of the arches of
the vertebrae ; thence it is collected, at each of tha intervertebral foramina,
by two or three small converging branches, which open into some of the
veins outside the vertebral column in front, viz., into the lumbar, azygos,
and cervical veins. Into these, also, the contents of the great spinal veins
are conveyed by the short communicating branches already noticed.
LOWER VENA CAVA.
The lower or ascending vena cava returns the blood from the lower limbs,
and from the viscera of the pelvis and abdomen. It commences at the
junction of the two common iliac veins on the side of the fifth lumbar
vertebra, and thence ascends along the right side of the aorta, as far as the
posterior border of the liver ; it there becomes lodged in a groove in that
organ, after which it inclines forwards to reach the opening in the diaphragm
appropriated to it, and, after being enclosed in a fold of the pericardium,
terminates in the right auricle of the heart. A large valve is situated at
its entrance into the auricle, named the valve of Eustachius, which, however,
as already explained in the description of the heart, is only a vestige of
foetal structure, variable in size, and without influence in preventing reflux
of the blood.
TRIBUTARIES. Besides the common iliac veins, the inferior vena cava
receives the following.
a. The middle sacral vein, taking its course upwards on the front of the
sacrum, opens into the left common iliac vein, or into the commencement of
the vena cava.
b. The lumbar veins correspond in number with the arteries of the same
name : they commence by small dorsal branches in the muscles of the back ;
and by others from the walls of the abdomen, where they communicate
with the epigastric and other veins in the neighbourhood. Having reached
the spine, they receive branches from the spinal plexuses, and proceed forward
upon the bodies of the vertebrae, behind the psoas muscle : those on the left
side, passing behind the aorta, terminate in the back of the vena cava.
Some of these veins are frequently found to unite into a single trunk before
their termination. The lumbar veins of the same side communicate with
each other by branches which cross in front of the transverse processes.
Not unfrequently a branch of this description is met with, called the
ascending lumbar vein, which connects more or less completely the common
iliac vein, the ilio-lumbar and lumbar veins, and the azygos vein.
c. The spermatic veins, proceeding upwards from the testicle and
forming a part of the constituents of the spermatic cord, enter the abdomen,
and ascend on the psoas muscle behind the peritoneum. Below the
i i
474 LOWER VENA CAVA.
abdominal ring there are numerous convoluted branches forming the spermatic
plexus (plexus pampiniformis). These branches gradually unite, and form a
single vessel, which opens on the right side into the lower vena cava, and on
the left into the renal vein. The spermatic veins sometimes bifurcate before
their termination, each division opening separately ; in this case, the veins
of the right side may be found communicating with the vena cava and the
renal vein.
In the female the ovarian veins have the same general course as the
ovarian arteries ; they form a plexus near the ovary (ovarian or pampiniform
plexus) in the broad ligament, and communicate with the uterine plexus.
Valves exist in the spermatic veins in man (Monro) ; and, in exceptional
cases, they have been also seen in the ovarian veins (Theile).
d. The renal or emulgent veins are short, but of very considerable size.
That of the left side is longer than that of the right, and passes in front of
the aorta. They join the vena cava at nearly a right angle. The renal veins
usually receive branches from the suprarenal capsules ; the left has also
opening into it the spermatic vein of the same side.
e. The capsular or suprarenal veins, though actually small, are, relatively
to the organs from which they arise, of considerable size. On the right
side the vein ends in the vena cava, and on the left in the renal or the
phrenic vein.
/. The phrenic veins follow exactly the course of the arteries supplied to
the diaphragm by the abdominal aorta.
g. The hepatic veins return from the liver the blood sent to that organ
by the portal vein and hepatic artery. They converge to the groove in
which the inferior vena cava lies, and pass at once obliquely into that vein.
There are usually three sets of hepatic veins proceeding to this common
point : those from the right and left lobes are oblique in their direction,
those from the middle of the liver and the lobule of Spigelius have an
intermediate position and course. The hepatic veins have no valves : but,
owing to their oblique entrance into the vena cava, a semiluuar fold is seen
at the lower border of the orifice of each vein.
PECULIARITIES. The lower vena cava presents some occasional deviations from its
ordinary condition, which may be briefly noticed.
In the lower part of its course, it is sometimes placed to the left side of
the aorta, and, after receiving the left renal vein, resumes its ordinary position by
crossing over the great* artery. Less frequently, the vena cava is placed altogether
on the left side, and is continued upwards to the heart, without any change in its
direction ; this occurs in cases of transposition of the thoracic and abdominal viscera
and of the great vessels.
In a more numerous class of cases, the left common iliac vein, instead of joining
the right in its usual position, is connected with it only by a small branch, and then
ascends on the left side of the aorta. After receiving the left renal vein, it crosses
over the aorta, and terminates by uniting with the common iliac vein of the right
side. In these cases, the vena cava inferior can be said to exist only at the
upper part of the abdomen, and below this point there is a vein on each side of the
aorta.
Lastly, the lower vena cava, instead of ending in the right auricle of the heart,
has been seen to join the right azygos vein, which is then very large ; eo that the
blood from the lower, as well as from the upper part of the body, is returned to the
heart through the upper vena cava. In this case, the hepatic veins do not join the
lower cava, but pass directly into the right auricle, at the usual place of termination
of the great vein.
The left renal vein has been seen to cross behind the aorta.
In a remarkable case, observed by Rothe, one of the hepatic veins ended, not in
VEINS OF THE LOWER LIMB.
475
Fig. 322.
the lower cava, nor in the right auricle, but in the right ventricle of the heart, its
orifice being guarded by valves. (Act. Acad. Joseph. Med. Chir. Vindobonensis, t. i.
p. 233, tab. 5. Vindobonai, 1788.)
VEINS OF THE LOWER LIMB AND PELYIS.
The veins of the lower limb are divisible into two sets, those of one being
deeply seated, those of the other running in the
superficial fascia. All the veins of the lower limb,
as high as the femoral venous trunk, are provided
with valves, and these are more numerous than in
the veins of the upper limb. The deep veins have
more valves than the subcutaneous set.
Fig. 322. OUTLINE OF THE SUPERFICIAL VEINS OF THE
LOWER LIMB.
1, the saphenous aperture of the fascia lata; , super-
ficial epigastric vein ; b, external pudic ; c, superficial cir-
cumflex iliac ; d, external or short saphenous beginning ou
the dorsum of the foot (see Fig. 326).
SUPERFICIAL VEINS OP THE LOWER LIMB.
Immediately beneath the integument, on the
dorsum of the foot, there exists a network of
veins forming an arch, from which issue two
principal trunks, which are named the internal or
long and the external or short saphenous veins.
The internal or long saphenous vein extends
from the ankle to within an inch and a half of
Poupart's ligament. Taking rise from the plexus
of veins on the dorsum of the foot, it passes up-
wards in front of the inner ankle, and along the
inner border of the tibia, accompanied by the
internal saphenous nerve. It inclines a little back-
wards as it passes the inner condyle of the femur,
and ascending along the inner and fore part of the
thigh, it terminates in the femoral vein, at the
saphenous opening in the fascia lata, through which
it passes.
In the leg it communicates with the deep veins
accompanying the anterior and posterior tibial
arteries, and in the thigh one or more branches
pass between it and the femoral vein. This long
vein has a variable number of valves. Sometimes
six have been counted ; in other cases only four,
or even two. It contains more in its course
through the thigh than in the leg.
TRIBUTARIES. The long saphenous vein is joined in its
course by numerous cutaneous vessels. Close to its termi-
nation it receives, besides a considerable anterior branch,
the superficial epigastric, external pudic, and superficial
circumflex iliac veins, corresponding severally to arterial branches of the same name.
i i 2
476
VEINS OF THE LOWEE LIMB AND PELVIS.
It is also usually joined near its termination by & posterior branch of considerable
size, coming from the posterior and inner part of the thigh.
The external or short saphenous vein proceeds from branches, which arise
along the outer side of the dorsum of the foot. It passes behind the
Fig 323 Fig. 323. OUTLINE OF THE POSTERIOR OR SHORT SAPHENOUS
VEIN.
The vein, commencing on the dorsum and outside of the
foot, is seen to pass up -behind the outer ankle and to dip
beneath the fascia in the popliteal space.
outer ankle, and gradually inclines backwards to
ascend along the border of the tendo Achillis and on
the belly of the gastrocnemius muscle, accompanied
by the external saphenous nerve ; running upwards
between the heads of the gastrocnemius, it unites
with the popliteal vein. Opposite the ankle and
along the leg it communicates with the deep veins :
and it receives superficial accessory veins from the
outer part of the foot and the back of the leg.
THE DEEP VEINS OF THE LOWEll LIMB.
The deep veins accompany the arteries and their
branches, following exactly their distribution. Those
below the knee, being for the most part disposed in
pairs, and presenting the disposition described in the
corresponding veins of the upper limb, are named the
vena comites of the vessels with which they are as-
sociated. The vense comites of the arteries of the
leg, namely, the anterior and posterior tibial veins
(the latter having previously received the peroneal],
unite near the lower border of the popliteus muscle,
and form by their junction the popliteal vein. The
valves of the deep veins of the leg are very numerous, ten or twelve being
sometimes found between the heel and the knee.
The POPLITEAL VEIN, thus formed, receives smaller branches correspond-
ing with the articular and muscular arteries, and the larger branch named
the external saphenous vein. In its course through the ham, the popliteal
vein is placed at first internally to the popliteal artery, then behind, and
lastly to the outer side of it, but always posteriorly and between it and the
nerve. Thus situated, it passes up through the aperture in the adductor
maguus, and becomes continuous with the femoral vein.
PECULIARITIES. The union of the veins which form the popliteal is often farther
up than usual, and the lower part of the artery is accompanied by t\vo veins. This
arrangement in some rare cases extends to the entire length of the artery.
The FEMORAL VEIN extends, like the artery which it accompanies, through
the upper two-thirds of the thigh, and terminates at Poupart's ligament in
the external iliac vein. Placed at first outside the artery, it gradually inclines
inwards behind it, and on reaching Poupart's ligament, lies on the inner
side, on the same plane with the artery, and separated from it only by a
slight partition of the membranous sheath, by which they are both invested.
FEMOBAL AND ILIAC VEINS.
477
ID the lower part of its course, the vein receives all the branches which
accompany the offsets of the chief artery. In the upper part, the deep
femoral vein opens into it, having first received all the branches from
muscles supplied by the deep femoral
artery. Near its termination the fe- Fig. 324.
moral vein is joined by the internal
saphenous vein.
Fig. 324. VIEW ? THE BLOOD-VESSELS
OP THE GROIN AND NEIGHBOURING PARTS
(fromR. Quain).
The full description of this figure will be
found at p. 436. The following numbers
indicate the veins : 2, the femoral vein ; 3,
the large or internal saphenous vein ; 3',
anterior saphenous ; 4, superficial circumflex
veins with twigs to the inguinal glands ;
5, superficial epigastric ; 6, superficial
pudic.
The femoral vein occasionally pursues
a course different from that of the artery
along the thigh. Extending upwards from
the popliteal space, the vein, in such cases
perforates the adductor magnus above the
ordinary position, and, joining with the
deep femoral vein, first approaches the
femoral artery at the groin. The same
vein is sometimes double in a small part,
or more rarely in almost its whole
length.
EXTERNAL ILIAC VEIN.
The external iliac vein is the continuation of the femoral vein from
Poupart's ligament to the junction of the internal iliac vein, in the neigh-
bourhood of the sacro-iliac articulation. It is at first internal to the
artery, and on the left side it continues in that position, but on the right
side it gradually inclines somewhat behind the artery. It does not possess
valves.
TRIBUTARIES. Near its commencement at Poupart's ligament, the external iliac
vein receives the circumflex iliac and the epigastric veins.
INTERNAL ILIAC VEIN.
The internal iliac vein is formed by the union of branches which accom-
pany the corresponding branches of the internal iliac artery. The umbilical
vein of the foetus, however, which in the cord accompanies the corresponding
arteries, diverges from these arteries within the body, and passes upwards
to the liver. The internal iliac vein lies behind the corresponding artery
in front of the sacro-iliac articulation, and, after a short course upwards
to the margin of the pelvis, joins with the external iliac vein to form the
common iliac. No valves are found in the trunk of the internal iliac vein,
but they exist in its branches.
478
VEIXS OF THE LOWER LIMB AND PELVIS.
TRIBUTARIES. The tributaries of the internal iliac vein correspond in
general to the various branches of the internal iliac artery, with the
exception that the internal pudic vein does not receive the main supply
of blood from the dorsal vein of the penis. The visceral veins are remark-
able for their size and frequent anastomoses, and have been described as
forming a series of plexuses, severally named the vesical, prostatic, hcemor-
rhoidal, uterine, and vaginal.
Fig. 3'25. INTERNAL
VIEW OF THE MALR
PELVIS FKOM THE
LEFT SIDE, TO SHOW
THE PRINCIPAL
VEINS.
The greater part
of the os innomina-
tum and pelvic wall
of the left side, and
the upper parts of
the rectum and
urinary bladder, have
been removed : the
left common iliac and
the right internal
iliac arteries, and the
left external and in-
ternal iliac veins, have
been cut short, a,
the right psoas mag-
nus muscle ; b, the
anterior superior iliac
spine ; c, Poupart's
ligament ; d, the
cavernous and spongy
bodies of the penis
divided near the i oot ;
+ , the spongy body
of the bulb, above
which the mem-
branous part of the
urethra ; the prostate,
&c. ; e, the left os
pubis close to the
symphysis ; f, the
anus ; g, the spine of
the ischium with the short sacro-sciatic ligament; 7i, auricular sacro-iliac surface; i,
interior of the urinary bladder ; k, exterior of the rectum ; I, transverse process of the
fourth lumbar vertebra ; 1, lower part of the vena cava inferior ; 1', abdominal aorta ; 2,
common iliac veins ; 2', right common iliac artery ; 3, external iliac veins; 3', external
iliac artery ; 4, internal iliac veins, that of the right side entire, that of the left divided
and in great part removed ; 5, middle and other veins of the sacral plexus ; 6, ilio-lumbar
and lumbar veins ; 7, right gluteal and upper lateral sacral veins ; 8, 8', obturator vein
and artery of the right side ; 9, pelvic plexus of veins of the right side ; 9', that of the
leftside connected with the lower vesical plexus; 10, placed on the right side on the
short sacro-sciatic ligament immediately below the division of the internal iliac vein into
the pudic and sciatic veins : on the left side, below 4, the sciatic vein is cut short ; 10,
lower down, the pudic vein; 10', the perineal veins ; 11, placed on the prostate among
the lower vesical veins, into one of which the left dorsal vein of the penis, 11, is seen to
pass ; 12, placed on the lower part of the rectum, may indicate the plexus of hasmorrhoidal
The vesical plexus presents vessels over the whole of the bladder external
ILIAC YEIXS PORTAL SYSTEM. 479
to its muscular coat, but they are particularly rich towards the base of the
organ, and are there closely connected with the prostatic and hajmorrhoidal
plexuses in the male, and with the vaginal plexus in the female.
The prostatic plexus receives two large vessels, one at each side, the divi-
sions of the dorsal vein of the penis. These, coursing downwards and
backwards on the sides of the prostate gland, expand into a close network
at the base of the gland, which is quite encircled by it.
The hcemorrhoidal plexus consists of enlarged and. copiously anastomosing
veins in the walls of the lower part of the rectum, immediately underneath
the mucous membrane. From it proceed superior, middle, and inferior
hsemorrhoidal veins accompanying the arteries of the same name, and it
communicates freely with the plexuses in front of it. The superior
hsemorrhoidal vein being a branch belonging to the portal system, the
hsemorrhoidal plexus forms a very direct communication between the portal
and general venous systems.
The vaginal plexus surrounding the vagina, principally in its lower part,
communicates freely with the hsemorrhoidal and vesical plexuses.
The uterine plexus pours its blood in greatest part into the ovarian veins,
and is not considerable except in pregnancy.
The dorsal vein of the penis commences by branches which issue from the
glans penis, and form in the first instance two veins, one at each side of the
middle line, in the dorsal groove of the penis. These receive branches from
the spongy body of the penis, and some superficial veins which accompany
the external pudic arteries, and, proceeding backwards, unite and form a
short trunk which enters the pelvis beneath the subpubic ligament. Here
it divides into two branches, which are directed obliquely downwards over
the prostate and the neck of the bladder, and are united with the prostatic
plexus.
COMMON ILIAC VEIN.
The common iliac vein is formed by the confluence of the external and
internal iliac veins. Extending from the sacro-iliac articulation upwards to
near the junction of the fifth with the fourth lumbar vertebra, at a point
a little to the right of the middle line, the two common iliac veins unite to
form the lower or ascending vena cava. The right vein is shorter than the
left, and is nearly vertical in its direction. The right vein is placed
behind, and then to the outer side of its artery ; whilst the left vein is to
the inner side of the left common iliac artery, and then passes behind the
right. These veins are destitute of valves.
PORTAL SYSTEM OF VEINS.
The portal vein differs from other veins of the body in being subdivided
into branches at both its extremities. The branches of origin, by the
union of which it may be said to be formed, are the veins of the chylo-
poietic viscera, viz., the stomach, intestine, pancreas, and spleen; the
other branches, or those of distribution, ramifying after the manner of an
artery in the substance of the liver, convey to the capillaries of that organ
the blood collected in the main trunk. This blood, together with that of
the hepatic artery, after having served for the secretion of the bile and the
nourishment of the liver, is withdrawn from that organ by the hepatic veins,
and carried by them into the vena cava inferior.
The PORTAL VEIN or VENA FOOTS: is about three inches in length.
Commencing at the junction of the splenic and superior mesenteric veins, it
480
POETAL VEIN.
passes upwards and a little to the right to reach the transverse fissure of the
liver. It is placed close behind the hepatic artery and the bile-duct : and
Fig. 326. Fig. 326. VIEW OP THE PRIN-
CIPAL BRANCHES OF THE VENA
PORT^J. i
1, lower surface of the right
lobe of the liver ; 2, stomach ; 3,
spleen ; 4, pancreas ; 5, duodenum ;
6, ascending colon ; 7, small intes-
tines ; 8, descending colon ; 8, vena
portse dividing in the transverse
fissure of the liver ; 6, splenic vein ;
c, right gastro-epiploic. ; d, inferior
mesenteric ; e, superior mesenteric
vein ; /, superior mesenteric ar-
tery.
is surrounded by the fila-
ments of the hepatic plexus
of nerves, together with nu-
merous lymphatics. All these
are imbedded in loose con-
nective tissue, and enclosed
within the layers of the small
omentum. Within the trans-
verse fissure it is somewhat
enlarged, and is there named
sinus of the portal vein.
Near the right end of the
transverse fissure, the vena
portse divides into two
branches. That of the right
side enters directly the sub-
stance of the corresponding
lobe of the liver, and spreads out into branches, each of which is accom-
panied by an offset of the hepatic artery and of the hepatic duct. The
left branch, which is smaller, but necessarily longer, passes across to gain
the left end of the transverse fissure, where it enters the liver and ramifies
like the preceding branch.
TRIBUTARIES. The principal branches which by their union contribute to
form the vena portse are the coronary vein of the stomach, the superior
mesenteric, and the splenic veins. The cystic vein is also sometimes a
lateral tributary of the portal vein, but more frequently proceeds from its
right branch.
The coronary vein of the stomach lies parallel with the artery of the same
name. Its size is inconsiderable, and its direction transverse from the
cardiac to the pyloric end of the stomach along the small curvature. On
reaching the latter point it turns downwards, and opens into the trunk of
the vena portse.
The SPLENIC VEIN, a vessel of very considerable size, returns the blood
not only from the spleen, but also from the pancreas, the duodenum, the
greater part of the stomach and omentum, the descending colon, and part
of the rectum. It commences by five or six branches, which issue sepa-
SUPEBIOE, MESENTERIC VEIN.
481
rately from the fissure of the spleen, and soon join to form a single vessel.
It is directed from left to right beneath the pancreas, in company with the
splenic artery, below which it is placed. On reaching the front of the spine
it joins the superior mesenteric vein, nearly at a right angle. It receives
Fig. 327. DIAGRAMMA- Fig. 327.
TIC OUTLINE OP THE
PORTAL VEIN AND ITS
RELATION TO THE LlVER,
&c. 4
The liver is supposed
to be turned upwards so
as to present a poi'tion of
its under surface. a,
gall-bladder ; 6, square
lobe ; c, left lobe ; 1,
trunk of the vena portse ;
2, great or superior me-
senteric vein ; 2', its
middle colic branch, form-
ing loops of communica-
tion between the right
and left colic veins ; 3,
intestinal branches ; + ,
small pancreatico-duode-
nal branch ; 4, right
colic branch ; 5, ileo-
colic ; 6, coronary vein of
the stomach ; + +, right
gastro-epiploic ; 7, sple-
nic vein ; 7', its branches
to the spleen ; 7", its
branches to the stomach ;
8, inferior mesenteric
vein ; 9, left colic branch ;
9', its communication
with the middle colic ;
10, sigmoid ; 11, hsemor-
rhoidal ; 12, the right, and
13, the left division of the
vena portse in the trans-
verse fissure of the liver ;
14, the obliterated cord
of the umbilical vein
passing through the an-
tero-posterior fissure to
join the left division of
the vena portse ; 15, the
obliterated cord of the
ductus venosus passing
from the left division of the vena portse to one of the hepatic veins connected with 16, the
vena cava inferior, of which a part is represented in shade.
gastric branches (vasa brevia) from the left extremity of the stomach, the
left gastro-epiploic vein, some pancreatic and duodenal branches, and also the
inferior mesenteric vein.
MESENTEKIC VEINS. The superior mesenteric vein lies to the right side,
and somewhat in front of the artery of the same name. The distribution of
its branches corresponds with that of the superior mesenteric artery, and it
returns the blood from the several parts supplied by that vessel, viz., from
the small intestine, and from the ascending and transverse parts of the.
482
CARDIAC VEIXS.
colon. The trunk, formed by the union of its several branches, inclines
upwards and to the right side, passing in front of the duodenum and behind
the pancreas, where it joins with the splenic vein to form the venae portae.
The branches of the inferior mesenteric vein correspond with the ramifica-
tions of the aitery of the same name. They commence at the lower part of
the rectum in the hsemorrhoidal plexus, and unite into a single vessel near
the sigmoid flexure of the colon. From this point the vein proceeds up-
wards and inwards along the lumbar region, behind the peritoneum, crossing
between the transverse mesocolon and the spine, or farther to the left, and
then passing beneath and behind the pancreas, it reaches the splenic vein
in which it terminates.
VEINS OF THE HEART.
The greater number of the cardiac veins are collected into a large common
trunk which pours its blood into the posterior part of the right auricle, in
the angle between the inferior vena cava and the right auriculo-ventricular
orifice. The terminal part of this vein is considerably dilated, and is named
the coronary sinus. The principal veins leading into it are named the great,
the posterior, and the anterior or small coronary veins. Among these the
first alone deserves the name of coronary, as it surrounds the heart in the
left auriculo-ventricular groove.
Besides the larger cardiac veins which join the great coronary sinus,
there are also small separate veins (venae minimse cordis), which open
directly into the right auricle, especially along its right border. The open-
ings of these veins, as well as some depressions which do not admit veins,
have been named foramina Thebesii.
Fig. 328.
Fig. 328. VIEW OF THE ADULT HRART, FROM
BEHIND, TO SHOW THE CORONARY VEINS. ^
a, placed on the back of the right auricle,
points to the Eustachiau valve seen within
the opening of the inferior vena cava ; &, the
back of the left auricle ; c, back of the right
ventricle ; d, left ventricle ; e, vena cava supe-
rior ; /, arch of the aorta ; 1, sinus of the
great coronary vein ; 2, great coronary vein turn-
ing round the heart in the auriculo-ventricular
groove ; 3, 4, posterior branches ; 5, one of the
small right cardiac veins passing directly into
the right auricle ; 6, the vestige of the left
superior vena cava proceeding over the left
auricle downwards to join the coronary sinus.
The veins of the heart are without
valves excepting at their terminations.
The great cardiac vein (vena cordis
magna) is a vessel of considerable size,
and, from the way in which it coils round
the left side of the base of the heart,
or rather of the ventricle, it may be
named "coronary." Its chief branch
runs along the groove upon the fore part of the heart, corresponding with
the septum of the ventricles. Commencing at the apex of the heart, it
gradually increases in size as it approaches the base of the ventricles, and
then, inclining backwards and to the left side in the groove between the left
DEVELOPMENT OF THE VEIXS. 483
auricle and ventricle, ends in the coronary sinus : a valve of two segments
closes its aperture in the sinus. In this course it receives branches from
the ventricles, especially from the left, and also from the left auricle : and
as it passes round the thick margin of the left ventricle, it receives a vein of
some size, which ascends to join it.
The posterior cardiac veins ascend on the back of the ventricles, espe-
cially on the left, and open into the coronary sinus by four or more valved
orifices. One of these, larger than the rest ('middle or posterior cardiac
vein), ascends along the groove between the ventricles upon the posterior
surface of the heart. It commences by small branches at the apex of the
heart, which communicate with those of the preceding vein, and then
ascends to the base, receiving branches from the substance of both ventricles.
The small or anterior cardiac veins (vense cordis parvre) are several small
branches, which commence upon the anterior surface of the right ventricle,
and passing upwards and outwards, open separately into the right auricle,
after having crossed over the groove between it and the ventricle.
The coronary sinus is about an inch in length, and is placed at the back
of the heart in the transverse groove between the left auricle and ventricle,
where it is covered by the muscular fibres of the auricle. At one end it is
joined by a small vein from the right side, and opens into the right auricle
beneath the Thebesian valve ; at the other, it receives the large coronary
vein, and a small straight vein directed obliquely along the back of the left
auricle ; whilst between those points other veins enter it from the back of
the heart. All the veins joining it, except the small oblique vein, are pro-
vided with more or less complete valves at their terminations.
The coronary sinus, together with the small oblique vein above referred to, con-
sidered with reference to their early foetal condition and certain malformations to
which they are subject along with other neighbouring veins, may be looked upon
rather as the persistent terminal parts of a typically distinct left superior vena cava,
than as simply the main stem of the cardiac veins. The explanation of this will
be found in what follows on the development of these veins.
DEVELOPMENT OF THE GREAT VEINS.
In the young foetus before the development of the allantois, a right and a left
omphalo-niesenteric vein bring back the blood from the walls of the umbilical vesicle,
and unite to form a short trunk, which is continued into the auricular extremity
of the rudimentary heart.
In the first commencement of the placental circulation, or in the third week of fcetal
life (Coste), two umbilical veins have been seen coming from the placenta, and unit-
ing to form a short trunk, which opens into the common omphalo-mesenteric vein.
Very soon the right omphalo-mesenteric vein and right umbilical vein disappear.
In connection with the common trunk of the umbilical and omphalo-mesenteric veins
two sets of vessels make their appearance in the young liver. Those furthest from
the heart, named venae hepaticce, advehentes, become the right and left divisions of
the portal vein ; the others are the hepatic veins, vence hepaticce revehentes. The
portion of vessel intervening between those two sets of veins forms the ductus
venosus (p. 329), and the part above the hepatic vein, being subsequently joined by
the ascending vena cava, forms the upper extremity of that vein. Into the remaining
or left omphalo-mesenteric vein open the mesenteric and splenic veins. The part
above the latter forms the trunk of the portal vein ; and the portion of vessel be-
tween the union of this with the umbilical vein and the origin of the venae hepaticse
advehentes is so altered that the portal trunk opens into the commencement of the
right vena advehens.
At the time of the commencement of the placental circulation, two short trans-
verse venous trunks, the ducts of Cuvier, open, one on each side, into the auricle of
484
DEVELOPMENT OF THE VEINS.
the heart. Each is formed by the union of a superior and an inferior vein, named
the primitive jugular and the cardinal.
The primitive jugular vein receives the blood from the cranial cavity by channels
in front of the ear, which are subsequently obliterated ; in the greater part of its
extent it becomes the external j ugular vein ; and near its lower end it receives small
branches, which grow to be the internal jugular and subclavian veins. The cardinal
veins are the primitive vessels which return the blood from the Wolffian bodies, the
vertebral column, and the parietes of the trunk. The inferior vena cava is a vessel of
later development, which opens into the trunk of the umbilical and omphalo-mesenteric
veins, above the venae hepaticae revehentes. The iliac veins, which unite to form the
inferior vena cava, communicate with the cardinal veins. The inferior extremities of
the cardinal veins are persistent as the internal iliac veins. Above the iliac veins, the
Fig. 329. Fig. 329. DIAGRAMS ILLUSTRATING
THE DEVELOPMENT OP THE GREAT
VEINS (after Kolliker).
A, plan of the principal veins of the
foetus of about four weeks, or soon after
the first formation of the vessels of the
liver and the vena cava inferior.
B, veins of the liver at a somewhat
earlier period.
C, principal veins of the foetus at the
time of the first establishment of the
placental circulation.
D, veins of the liver at the same
period.
dc, the right and left ducts of Cuvier ;
ca, the right and left cardinal veins ;
.;', j, the jugular veins ; s, the subclavian
veins ; az, the azygos vein ; w, the um-
bilical or left umbilical vein ; u' in B,
the temporary right umbilical vein ; o,
the omphalo-mesenteric vein ; e/, the
right omphalo-mesenteric vein ; m, the
mesenteric veins ; p, the portal vein ;
p', p', the vense advehentes ; I, the duc-
tus venosus ; I', I', the hepatic veins ;
ci t vena cava inferior ; il, the division
of the vena cava inferior into common
iliac veins ; cr, the external iliac or
crural veins ; h, the hypogastric or in-
ternal iliac veins, in the line of continua-
tion of the primitive cardinal veins.
In C, li, in dotted lines, the trans-
verse branch of communication between
the jugular veins which forms the left
innominate vein ; ri, the right innomi-
nate vein ; ca', the remains of the left
cardinal vein by which the superior
intercostal veins fall into the left in-
nominate vein ; above p, the obliquely
crossing vein by which the hemiazygos
joins the azygos vein.
cardinal veins are obliterated in a considerable part of their course ; their upper
portions then become continuous with two new vessels, the posterior vertebral veins of
Rathke, which receive the lumbar and intercostal twigs.
As development proceeds, the direction of the ducts of Cuvier is altered by the
descent of the heart from the cervical into the thoracic region, and becomes con-
tinuous with that of the primitive jugular veins. A communicating branch makes its
appearance, directed transversely from the junction of the left subclavian and jugular
veins, downwards, and across the middle line to the right jugular; and further down
DEVELOPMENT OF THE YEIXS.
485
in the dorsal region between the posterior vertebral veins a communicating branch
passes obliquely across the middle line from right to left. The communicating branch
between the primitive jugular veins forms the left innominate vein. The portion of
vessel between the termination of the right subclavian vein and the termination of the
communicating branch becomes the right innominate vein. The portion of the primi-
tive jugular vein below the communicating vein, together with the right duct of Cuvier,
forms the vena cava superior, while the cardinal vein opening into it is the extremity
of the great vena azygos. On the left side, the portion of the primitive jugular vein
placed below the communicating branch, and the cardinal and posterior vertebral
veins, together with the cross branch between the two posterior vertebral veins, are
Fig. 330.
Fig. 330, A. and B. DIAGRAMMATIC OUTLINES OP THE VESTIGE OP THE LEPT SUPERIOR
CAVA AND OF A CASE OP ITS PERSISTENCE (sketched after Marshall).
A, Brachio-cephalic veins with the superior intercostal, azygos, and principal cardiac
veins.
B, the same in a case of persistence of the left superior cava, showing its communica-
tion with the sinus of the coronary vein. The views are supposed to be from before, the
parts of the heart being removed.
1, 1', the internal jugular veins ; 2,2', subclavian veins ; 3, right innominate ; 3', right
or regular superior cava ; 4, in A, the left innominate ; in B, the transverse or communi-
cating vein between the right and left superior venas cavae ; 5, in A, the opening of the
superior intercostal vein into the innominate ; 5', vestige of the left superior cava or duct
of Cuvier ; 5, 5', in B, the left vena cava superior abnormally persistent along with a
contracted condition of 4, the communicating vein ; 6, the sinus of the coronary vein ; 6',
branches of the coronary veins ; 7, the superior intercostal trunk of the left side, or left
cardinal vein ; 8, the principal azygos or right cardinal vein ; 7', 8', some of the upper
intercostal veins ; 9, the opening of the inferior vena cava, with the Eustachian valve.
converted into the left superior intercostal and left superior and inferior azygos veins.
The variability in the adult arrangement of these vessels depends on the various
extent to which the originally continuous vessels are developed or atrophied at one
point or another. The left duct of Cuvier is obliterated, except at its lower end,
which always remains pervious as the coronary sinus. Even in the adult, traces of
the existence of this vessel can always be recognised in the form of a fibrous band,
or sometimes even a narrow vein, which descends obliquely on the left auricle ; and
in front of the root of the left lung there remains a small fold of the serous membrane
486
THE ABSORBENTS.
of the pericardium, the vestigial fold of the pericardium, so named by Marshall, to
whom is due the first full elucidation of the nature and relations of the left primitive
vena cava.
The left duct of Cuvier has been observed persistent as a small vessel in the adult.
More frequently a right and left innominate vein open separately into the right
auricle, an arrangement which is also met with in birds and in certain mammalia,
and which results from the vessels of the left side being developed similarly to those
of the right, while the cross branch remains small or absent. (Quain on the Arteries,
plate 58, figs. 9 and 10.)
Fi<*. 331. Fig. 331. VIEW OF THE FOSTAL HEART
AND GREAT VESSELS, FROM THE LEFT
SIDE, TO SHOW THE VESTIGE OF THE
LEFT SUPERIOR CAVA VEIN IN SITU.
(This figure is planned after one of
Marshall's, and slightly altered accord-
ing to an original dissection.)
a, right auricle; &, left auricle and
pulmonary veins ; e, the conus arteriosus
of the right ventricle; d, the left ven-
tricle ; e, descending aorta ; + , vestigial
fold of the pericardium ; /, arch of the
aorta, with a part of the pericardium
remaining superiorly ; g, main pulmonary
artery and ductus arteriosus ; g', left pul-
monary artery ; 1, 1', right and left in-
ternal jugular veins ; 2, 2', subclavian
veins ; 3, right innominate and superior
vena cava ; 4, left innominate cr com-
municating vein ; 5, 5', remains of the
left superior cava and duct of Cuvier, passing at + in the vestigial fold of the pericardium,
joining the coronary sinus, 6, below, and receiving above the superior intercostal vein, 7 ;
7', 7', the upper and lower intercostal vein, joining into one.
A case is recorded by Gruber, in which the left vena azygos opened into the
coronary sinus, and was met by a small vein descending from the union of the sub-
clavian and jugular. (Reichert and Dubois Reymond's Archiv, 1864, p. 729.) In
this case, the jugular veins had been developed in the usual manner, while the left
vena azygos continued to pour its blood into the duct of Cuvier.
(Consult Kolliker, Entwickelungsgeschichte, p. 414, et seq. ; J. Marshall on the
Development of the great Anterior Veins in Man and Mammalia, in Phil. Trans.,
part i., 1850; and Wenzel Gruber, Uber die Sinus Communis und die Valvulse der
Venae Cardiacae, &c., in Me"m. de TAcad. imper. des Scien. de St. Petersbourg, 1864 ;
and in Virchow's Archiv, Jan. 1865.)
THE ABSORBENTS.
The absorbent vessels are divisible physiologically into two sets ; the
lacteals, which convey the chyle from the alimentary canal to the thoracic
duct ; and the lymphatics, which take up the lymph from all the other parts
of the body, and return it into the venous system. Anatomically con-
sidered, however, the lacteals are not different from the lymphatics, and
may be regarded as the absorbents of the mucous membrane of the intestine.
The larger lacteals and lymphatics are provided with valves, which give them,
when distended, a somewhat moniliform appearance j and both are connected
in their course with lacteal or lymphatic glands.
THORACIC DUCT.
487
Fig. 332.
The general anatomy of the absorbents having been elsewhere detailed,
only their course and position remain to
be here described. They are gathered
into a right and a left trunk, which open
into the angles of union of the subclavian
and internal jugular veins. The large
vessel of the left side traversing the thorax
is named the thoracic duct : it receives not
only the lymphatics of its own side of
the head and arm, but likewise the lym-
phatics of both lower limbs, and the whole
of the lacteals. The vessel of the right
side is named the right lymphatic duct, and
receives lymphatics only.
-5'
Fig. 332. SKETCH OF THE THORACIC DUCT WITH
THE PRINCIPAL SYSTEMIC VEINS.
The full description of this figure will be found
at p. 454.
10, 10, indicate the thoracic duct ; the lower
number is close to the receptaculum chyli, the upper
is on the fourth dorsal vertebra, above which the
duct inclines to the left ; 6, on the left subclavian
vein, marks the termination of the duct in the
angle of uuion of the subclavian and internal jugu-
lar veins ; 5, on the right subclavian vein, indicates
the similar termination of the right lymphatic
trunk.
1U
THORACIC DUCT.
The thoracic duct is the common trunk
which receives the absorbents from both
the lower limbs, from the abdominal viscera
(except part of the upper surface of the
liver), and from the walls of the abdomen,
from the left side of the thorax, left lung,
left side of the heart, and left upper limb,
and from the left side of the head and
neck. It is from fifteen to eighteen inches
long in the adult, and extends usually from
the second lumbar vertebra to the root of
the neck. Its commencement, however, is
often as low as the third lumbar vertebra ;
and in some cases as high as the first
lumbar, or even upon the last dorsal ver-
tebra. Here there is usually a dilatation
of the duct, of variable size, which is
called receptaculum chyli (Pecquet), and is
the common point of junction of the lym-
phatics from the lower limb with the trunks
of the lacteal vessels.
The lower part of the thoracic duct is
generally wider than the rest, being about
three lines in diameter ; it lies at first to the right side of or behind the
488 LYMPHATICS OF THE LOWER LIMB.
aorta ; it then ascends on the right side of that vessel, in contact with the
right crus of the diaphragm, to the thorax, where it is placed at first upon
the front of the dorsal vertebrae, between the aorta and the azygos vein.
The duct ascends, gradually inclining to the left, and at the same time dimi-
nishing slightly in size, until it reaches the third dorsal vertebra, where,
passing behind the arch of the aorta, it comes into contact with the oeso-
phagus, lying between the left side of that tube and the pleura. Con-
tinuing its course into the neck to the level of the upper border of the
seventh cervical vertebra, it changes its direction and turns forwards, at the
same time arching downwards and outwards so as to describe a curve over
the apex of the pleura, and then terminates on the outer side of the internal
jugular vein, in the angle formed by the union of that vein with the sub-
clavian. The diminution in the size of the duct as it ascends is such that
at the fifth dorsal vertebra it is often only two lines in diameter, but above
this point it again enlarges. The duct is generally waving and tortuous in
its course, and is constricted at intervals so as to give it a varicose ap-
pearance.
The thoracic duct is not always a single trunk throughout its whole extent ; it
frequently divides opposite the seventh or eighth dorsal vertebra into two trunks,
which soon join again ; sometimes it separates for a short distance into three divisions,
which afterwards unite, and enclose between them spaces or islets. Cruikshank in
one case found the duct double in its entire length ; " in another triple, or nearly so."
In the neck, the thoracic duct often divides into two or three branches, which in some
instances terminate separately in the great veins, but in other cases unite first into a
common trunk. In a case of right aortic arch the thoracic duct has been observed to
end in the veins of the right side (A. Thomson).
The thoracic duct has numerous double valves at intervals throughout
its whole course, which are placed opposite to the nodulated parts of the
vessel. They are more numerous in the upper part of the duct. At the
termination of the duct in the veins there is a valve of two segments, so
placed as to allow the contents of the duct freely to pass into the veins,
but which would effectually prevent the reflux of either chyle or blood into
the duct.
THE RIGHT LYMPHATIC DUCT.
The right lymphatic duct is a short vessel, about a line or a little more
in diameter, and about a quarter or half an inch in length, which receives
the lymph from the absorbents of the right upper limb, the right side of
the head and neck, the right side of the chest, the right lung, and the right
half of the heart, and from part of the upper surface of the liver. It
enters obliquely into the receding angle formed by the union of the right
subclavian and internal jugular veins, where its orifice is guarded by a double
valve.
LYMPHATICS OF THE LOWER LIMB
AND SURFACE OF THE LOWER HALF OF THE TRUNK.
The lymphatics of the lower limb are arranged in a superficial and a deep
series. Those of the superficial series, together with the superficial lym-
phatics of the lower half of the trunk, converge to the superficial inguinal
glands ; with the exception of a few which dip into the popliteal space.
Those of the deep series converge to the deep inguinal glands.
LYMPHATICS OF THE LOWER LIMB.
The popliteal lymphatic glands,
usually very small, and four or five in
number, surround the popliteal vessels,
and are imbedded in a quantity of
loose fat. They receive from below
the deep lymphatics of the leg, and
those which accompany the short
saphenous vein ; and from them pro-
ceed efferent vessels, which ascend
with the femoral artery to the groin.
Fig. 333. VIEW OP THE SUPERFICIAL LYM-
PHATIC VESSELS AND GLANDS OF THE EIGHT
GROIN AND LOWER LIMB, AS SEEN FROM
THE FRONT AND INNER SIDE (founded on
Mascagni and others), g
1, 1, upper inguinal glands receiving the
lower abdominal, the inguinal, penal, and
scrotal lymphatic vessels ; 2, 2, femoral or
lower inguinal glands, receiving the anterior
internal and external femoral lymphatic ves-
sels ; 2', the internal lymphatic vessels ; 3, 3,
large plexus of lymphatic vessels in the course
of the saphenous veins ; 4, the same descend-
ing upon the leg ; 5, posterior lymphatics of
the calf of the leg ; 6, lymphatic vessels of
the dorsum of the foot; 7, those of the heel
and inner ankle.
The superficial inguinal glands vary
much in number, amounting on an
average to eight or ten : they are
divisible into a superior or oblique
and an inferior or vertical set. The
oblique glands lie in the line of Pou-
part's ligament and receive lymphatics
from the integuments of the trunk and
genital organs, together with a few
from the upper and outer part of the
limb : the vertical glands surround the
upper part of the long saphenous vein,
and extend two or three inches down-
wards along the course of that vessel ;
they receive the greater number of the
lymphatics which ascend from the limb.
The efferent vessels of the superficial
inguinal glands perforate the fascia,
come into connection with those situ-
ated deeply, pass into the abdomen by
the side of the blood-vessels, and ter-
minate in a chain of lymphatics which
lie along the external iliac artery, and
end in the lumbar glands.
The deep-seated inguinal glands are
placed beneath the others, and surround
the femoral artery and vein.
Fig. 333.
490 THE ABSORBENTS.
The superficial lymphatics of the lower limb arise in two sets, one from
the inner part of the dorsum and sole of the foot, the other from the outer.
The inner vessels follow a similar course to that of the internal saphenous vein :
passing partly in front and partly behind the inner ankle, they ascend
along the inner side of the knee and front of the thigh, and terminate in
the superficial inguinal glands. The outer vessels, ascending from the outer
side of the foot, pass in great part obliquely across the popliteal space to
join the inner set above the knee ; in part they reach the inner set by
crossing in front of the tibia ; and a small number of them accompanying
the external saphenous vein, dip down between the heads of the gastrocne-
mius muscle, and end in the popliteal glands. From the middle line of
the back of the thigh lymphatics pass round on both sides to reach the
inguinal glands. (Mascagni, Vasorum Lymph. Historia, 1787.)
The deep-seated lymphatics of the lower limb are associated in their whole
course with the deep blood-vessels. In the leg they consist of three divi-
sions, namely, anterior tibial, posterior tibial, and peroneal. Neither these
nor the superficial absorbents pass through any lymphatic gland in the leg,
unless it be those lymphatics which accompany the anterior tibial artery, near
which a small gland is sometimes found on the front of the interosseous liga-
ment, above the middle of the leg. The several sets of deep lymphatics in the
leg enter the lymphatic glands situated in the popliteal space. The efferent
vessels from those glands are joined by others in contact with the branches
of the femoral artery, and enter the deep inguinal glands. Other deep
lymphatics, derived from the muscles of the gluteal region, and many pro-
ceeding from the adductor muscles of the thigh, enter the cavity of the
pelvis in company with the gluteal, sciatic, and obturator arteries, and pass
through a series of glands situated in the neighbourhood of the internal and
common iliac arteries.
The superficial lymphatics of the lower half of the trunk converge to
the superficial inguinal glands, the direction of some of them being indicated
by the superficial circumflex iliac and epigastric, and the external pudic
arteries. Externally they converge to the groin from the gluteal region and
from the lower part of the back, those from the back crossing others which
pass upwards to the axillary glands. Anteriorly they descend from the
greater part of the surface of the abdomen, crossing and mingling above
the umbilicus with vessels which ascend towards the axillary glands.
The superficial lymphatics of the penis usually form three vessels, two
being placed at the sides, and the other on the dorsum of the organ.
Commencing in the prepuce and beneath the mucous lining of the urethra,
they pass backwards, unite on the dorsum penis, and, again subdividing,
send branches on each side to the oblique inguinal glands. The deerj-seated
lymphatics of the penis pass under the pubic arch, and end in the glands
on the internal iliac artery.
The lymphatics of the scrotum pass to the superficial inguinal glands along
the course of the external pudic arteries.
The lymphatics of the external generative organs in the female present a
disposition similar to that existing in the male.
ABSORBENTS OF THE ABDOMEN AND PELVIS.
The external iliac lymphatic glands, from six to ten or more in number,
clustering round the external iliac artery, receive the efferent vessels from
both deep and superficial inguinal glands.
ABSORBENTS OF THE ABDOMINAL VISCERA. 491
The internal iliac lymphatic glands, a numerous series placed on the
internal iliac artery, and the sacral glands, placed in the hollow of the
sacrum, receive the lymphatics from the pelvic viscera and parietes.
The lumbar lymphatic glands are very large and numerous ; they are
placed in front of the lumbar vertebrae, around the aorta and vena cava.
To these proceed the efferent vessels of the glands already mentioned, as
well as those which accompany several of the branches of the abdominal
aorta.
The efferent absorbent vessels which proceed from the lumbar glands pro-
gressively increase in size, while their number diminishes, and at length
they unite into a few trunks, which, with those of the lacteals, form the
origin of the thoracic duct.
The deep lymphatics of the abdominal wall in part pass along the
circumflex iliac and epigastric arteries to the external iliac glands ; the
greater number are directed backwards with the ilio-lumbar and lumbar
arteries, and, being joined by the lymphatics from the muscles of the back,
pass behind the psoas muscle to the vertebral column, where they enter the
lumbar glands.
The lacteals (vasa lactea, chylifera) commence in the coats of the intes-
tines, by a very close plexus, and extend to the thoracic duct, in which
they all terminate : they are derived in far larger numbers from the small
than from the large intestine, so that they abound in the mesentery, and
particularly in that of the jejunum and ileum. Two series of absorbent
vessels are found along the tube of the intestine, having different positions
and directions : those nearest to the outer surface of the intestine run
longitudinally in the course of the canal, lying beneath the peritoneal coat ;
whilst others, placed more deeply between the muscular and mucous coats,
run transversely round the intestine, and are directed thence with the
arteries and veins along the mesentery, enclosed between the two layers of
the peritoneum. (Cruikshank, Anatomy of the Absorbent Vessels, p. 162.)
Sometimes the more superficial absorbents of the intestine are named
lymphatics, to distinguish them from the deep set which are those which
absorb the chyle from the cavity of the intestine. According to Teichmann
(Das Saugader- system, 1861, p. 75), the two plexuses have no capillary
anastomoses, but communicate only through valved vessels : this they do
freely. The lacteals, having entered the mesentery, take the course of the
blood-vessels, and pass through numerous lymphatic glands (mesenteric
glands).
The mesenteric glands vary in number from a hundred and thirty to a
hundred and fifty ; and in the healthy state are seldom larger than an
almond. They are most numerous in that part of the mesentery which
corresponds with the jejunum ; and they seldom occur nearer to the
attached border of the intestine than two inches. In mesenteric disease
they are subject to enlargement, and become the seat of unhealthy deposits.
Small glands in limited numbers are also disseminated irregularly between
the folds of the peritoneum connected with the large intestines.
Having passed through these glands, the lacteals gradually unite as they
approach the attached border of the mesentery, and so become diminished
in number but increased in size, until at length, near the root of the supe-
rior mesenteric artery, only two or three trunks remain, which end in the
thoracic duct. Sometimes, however, six or seven of these vessels open
separately into the commencement of the duct. Those from the descending
colon and its sigmoid flexure usually join some of the lumbar lymphatics, or
492
THE ABSORBENTS.
Fig. 234.
Fig. 334. -PRINCIPAL LYMPHATIC VESSELS AND GLANDS OF THE ABDOMEN AND PELVIS
(modified from Mascagni). 5
a, the abdominal aorta, the upper part of it having been removed to show the deepest
lumbar plexuses of lymphatics ; a', the vena cava inferior ; 6, the right, c, the left crus
of the diaphragm ; d, the right kidney ; e, the suprarenal body ; /, the ureter ; g, the
psoas muscle ; A, the iliacus ; Tc, the lower part of the sacrum within the pelvis ; 1, the
commencement of the thoracic duct ; 2, 3, 2, the largest of the lymphatic and lacteal
trunks which join the thoracic duct, the hepatic, splenic, gastric, &c. ; 4, the suprarenal
lymphatics ; 5, the renal, joining some of the lumbar plexus ; 6, the spermatic; 7, 7, the
lumbar lymphatic vessels and glands ; 7', 7', some of the lymphatics of the loins; 8, 8,
those surrounding the common iliac vessels, and proceeding from the lymphatics of the
pelvis and lower limb ; 9, 9 ? the external iliac ; 10, 10, the internal iliac receiving those
from the sacrum, walls of the pelvis, and at 11, 11, and at k, those from the viscera
(bladder and rectum) ; 12, lymphatics of the dorsum of the penis passing to those of the
groin ; 13, the deep femoral lymphatics and glands.
ABSORBENTS OF THE ABDOMINAL VISCERA. 493
turn upwards and open by a separate trunk into the lower end of the
thoracic duct.
The absorbents of the stomach, like those of the intestines, are placed, some
beneath the peritoneal coat, and others between the muscular and mucous
coats. Following the direction of the blood-vessels, they become arranged
into three sets. Those of one set accompany the coronary vessels, and
receiving, as they run from left to right, branches from both surfaces of the
organ, turn backwards near the pylorus, to join some of the larger trunks.
Another series, from the left end of the stomach, follow the vasa brevia,
and unite with the lymphatics of the spleen : whilst those of the third set,
guided by the right gastro-epiploic vessels, incline from left to right along
the great curvature of the stomach, from which they pass backwards, and
at the root of the mesentery terminate in one of the principal efferent lacteal
vessels.
The absorbents of the rectum, likewise in two strata, are frequently of
considerable size : immediately after leaving the intestine, some of them
pass through small glands which lie contiguous to it ; finally, they enter
the lymphatic glands situated in the hollow of the sacrum, or those higher
up in the loins. At the anus their capillary network is continuous with
that of the cutaneous absorbents.
The lymphatics of the spleen are placed, some immediately under its
peritoneal covering, others in the substance of the organ. Both sets
converge to the inner side of the spleen, come into contact with the blood-
vessels, and, accompanying these, pass through a series of small glands,
and terminate in the larger lymphatics of the digestive organs.
Lymphatics emerge from the pancreas at different points, and join those
derived from the spleen.
The lymphatics of the liver are divisible into three principal sets, according
as they are placed upon its upper or its under surface, or are spread through
its substance with the blood-vessels.
The lymphatic vessels on the upper surface of the liver incline towards
particular points, and so become distinguishable into groups, of which four
are usually enumerated. 1. From the middle of this surface five or six
branches run towards the falciform ligament, and, being directed forwards
on this membrane, they unite to form a large trunk, which passes upwards
between two slips of the attachment of the diaphragm, behind the ensiform
cartilage. Having reached the interpleural space behind the sternum, they
ascend through a chain of lymphatic glands found upon the internal mam-
mary blood-vessels. 2. The second group consists of vessels which incline
outwards towards the right lateral ligament, opposite to which they unite into
one or two larger lymphatics ; these pierce the diaphragm, and run forwards
upon its upper surface to join the preceding set of vessels behind the sternum.
In some cases, however, instead of passing into the thorax, they turn inwards
on reaching the back part of the liver, and, running upon the crus of the
diaphragm, open into the thoracic duct close to its commencement. 3.
Another set of lymphatics is found upon the left lobe of the liver ; the
vessels of which it is composed, after reaching the left lateral ligament pierce
the diaphragm, and, turning forwards, end in the anterior glands of the
mediastinum. 4. Finally, along the fore part of the liver some vessels will be
observed to turn downwards and join those placed upon the under surface.
The under surface of the liver is covered by an open network of lymphatic
vessels. On the right lobe they are directed over and under the gall-
bladder to the transverse fissure, where some join the deep lymphatics ;
494
THE ABSORBENTS.
Fig. 335. Fig. 335. DIAGRAMMATIC
OUTLINE OP THE PRIN-
CIPAL ABSORBENT VESSELS
AND DUCTS, 5
a, junction of the right
jugular and subclavian veins
in the right innominate ; &,
the same on the left side ;
1, the thoracic duct, show-
ing a division in its upper
part ; farther down a se-
paration into two vessels
enclosing a space between
them, and at its lower ex-
tremity, 1', the receptaculum
chyli ; 2, the principal cer-
vical lymphatic vessels with
the larger glands near their
terminations ; 3, 3', the
principal axillary lymphatic
vessels and glands, joined by
those from the shoulder and
lower part of the neck ; 4, 4',
the right and left internal
mammary and anterior medi-
astinal lymphatic vessels (re-
presented as more widely se-
parated than natural); on the
right side, 4' and 4", mark
the junction with the internal
mammary of the superior
hepatic and anterior superior
phrenic lymphatics ; 5, some
deeper mediastinal and peri-
cardiac lymphatics; 6, 6',
deep mediastinal lymphatics
passing into the right lym-
phatic trunk and thoracic
duct ; 7, the bronchial and
pulmonary ; 8, cesophageal ;
9, posterior diaphragmatic
lymphatics ; 10, the inter-
costal and neighbouring lym-
phatics of the posterior tho-
racic wall represented chiefly
on the left side ; at 10', is
shown a small collateral
trunk, formed by the union
of a number of the inter-
costal lymphatics; 11, 11,
short trunks leading into the
lower part of the thoracic
duct, which receive some of
the principal lymphatic ves-
sels from the spleen, stomach,
and pancreas, and the lacteal
vessels from the intestines ;
12, 12', several main vessels
which collect the principal
lymphatic vessels of the right and left lumbar plexus, and carry their contents into the
thoracic duct ; 13, 13', right and left renal lymphatics ; 14, 14', right and left spermatic
lymphatics ; 15, aortic plexus, which farther down is continuous with the sacral; 16, 16',
right and left lumbar plexus, which receive the principal lymphatics of the pelvis and
lower limbs.
ABSORBENTS OF THE PELVIC VISCERA. 495
whilst others, passing through some scattered lymphatic glands, are guided
by the hepatic artery to the right side of the aorta, where they terminate in
the thoracic duct. Branches also proceed to the concave border of the
stomach, between the folds of the small omentum, to join with the coronary
lymphatics of that organ.
The deep lymphatics of the liver accompany the branches of the portal
vein in the substance of the organ, and pass out of the gland by the
transverse fissure. After communicating with the superficial lymphatics,
and also with those of the stomach, they pass backwards, and join, at the
side of the cceliac artery, with one of the large lacteal trunks previously to
its termination in the thoracic duct.
The lymphatics of the kidney likewise consist of a deep and a superficial
set. Those placed upon the surface of the organ are comparatively small ;
they unite at the hilus of the kidney with other lymphatics from the
substance of the gland, and then pass inwards to the lumbar lymphatic
glands. The lymphatics of the suprarenal capsules unite with those of the
kidney. The lymphatic vessels of the ureter are numerous ; they com-
municate with those of the kidney and bladder, and for the most part
terminate by union with the former.
The lymphatics of the bladder, taking rise from the entire surface of that
organ, enter the glands placed near the internal iliac artery ; with these
are associated the lymphatics of the prostate gland and vesiculae seminales.
The lymphatics of the uterus, in the unimpregnated state of the organ,
are small, but during the period of gestation they are greatly enlarged.
Issuing from the entire substance of the uterus, the greater number descend,
together with those of the vagina, and pass backwards to enter the glands
upon the internal iliac artery ; thus following the course of the principal
uterine blood-vessels. Others, proceeding from the upper end of the uterus,
run outwards in the folds of peritoneum which constitute the broad liga-
ments, and join the lymphatics derived from the ovaries and Fallopian
tubes. The conjoined vessels then ascend with the ovarian arteries, near
the origin of which they terminate in the lymphatic vessels and glands
placed on the aorta and vena cava.
The lymphatics of the testicle commence in the substance of the gland,
and upon the surface of the tunica vaginalis. Collected into several large
trunks, they ascend with the other constituents of the spermatic cord, pass
through the inguinal canal, and accompany the spermatic vessels in the
abdomen to enter some of the lumbar lymphatic glands.
LYMPHATICS OF THE THORAX.
The lymphatic glands of the thorax. Along the course of the internal
mammary blood-vessels there are placed six or seven small glands, through
which pass the lymphatics situated behind the sternum ; they may be named
the anterior mediastinal glands. Between the intercostal muscles and in
the line of the heads of the ribs on the side of the spine is a set of glands,
named intercostal, which receive the lymphatics from the thoracic parietes
and the pleura ; their efferent ducts communicate freely with each other
and open into the thoracic duct. Three or four cardiac lymphatic glands
lie behind the aortic arch, and one before it : and another cluster, varying
from fifteen to twenty in number, is found along the oesophagus, con-
stituting the cesophageal glands. The bronchial glands, ten or twelve in
number, are of much larger size than those just mentioned. The largest of
496
THE ABSORBENTS.
them occupy the interval between the right and left bronchi at their diver-
gence, whilst others of smaller size rest upon the first divisions of these tubes
Fig. 336.
Fig. 336. LYMPHATIC VES-
SELS OF TUB HEAD AND
NECK AND OP THE UPPER
PART OP THE TRUNK
(from Mascagni).
The chest and pericar-
dium have been opened on
the left side, and the left
mamma detached and
thrown outwards over the
left arm, so as to expose a
great part of its deep sur-
face.
The principal lymphatic
vessels and glands are shown
on the side of the head and
face, and in the neck, axilla,
and mediastinum. Between
the left internal jugular vein
and the common carotid
artery, the upper ascending
part of the thoracic duct
marked 1, and above this,
and descending to 2, the
arch and last part of the
duct. The termination of
the upper lymphatics of
the diaphragm in the me-
diastinal glands, as well as
the cardiac and the deep
mammary lymphatics, are
also shown.
for a short distance
within the lungs. In
early infancy their co-
lour is pale red ; towards puberty, we find them verging to grey, and studded
with dark spots ; at a more advanced age they are frequently very dark or
almost black. In chronic diseases of the lungs they sometimes become en-
larged and indurated, so as to press on the air tubes and cause much irrita-
tion. They are frequently the seat of tuberculous deposits.
The deep lymphatics of the thoracic walls are divisible into two sets, the
sternal and the intercostal. The sternal lymphatics, commencing in the
muscles of the abdomen, ascend between the fibres of the diaphragm at its
attachment to the ensiform cartilage, and continue upwards behind the
costal cartilages to terminate on the left side in the thoracic duct, and on
the opposite side in the right lymphatic duct. They receive branches from
the upper surface of the liver, and small branches from the anterior parts of
the intercostal spaces. The intercostal lymphatics, passing backwards in
each intercostal space, receive, as they approach the spine, branches
coming forward through the intertransverse space, and enter the intercostal
glands, through the efferent ducts of which their contents are poured on
both sides of the body into the thoracic duct.
The lymphatics of the lungs, like those of other organs, form two sets,
one being superficial, the other deep-seated. Those at the surface run
beneath the pleura, where they form a network by their anastomoses.
LYMPHATICS OF THE THORAX.-UPPER LIMB. 497
Their number is considerable, but they are sometimes difficult of demon-
stration. The deep lymphatics run with the pulmonary blood-vessels.
Both superficial and deep lymphatics converge to the root of the lung, and
terminate in the bronchial glands. From these, two or three trunks issue,
which ascend along the trachea to the root of the neck, and terminate on
the left side in the thoracic duct, and on the right in one of the right
lymphatic trunks.
The lymphatics of the heart follow the coronary arteries and veins from
the apex of the organ towards the base, where they communicate with each
other, and those of each side are gathered into one trunk. The trunk from
the right side, running upwards over the aortic arch between the innominate
and left carotid arteries to reach the trachea, ascends to the root of the
neck, and terminates in the right lymphatic duct. The vessel from the left
side proceeding along the pulmonary artery to its bifurcation, passes through
some lymphatic glands behind the arch of the aorta, and ascends by the
trachea to terminate in the thoracic duct.
The lymphatics of the oesophagus, unlike those of the rest of the alimentary
canal, form only one layer, which lies internal to the muscular coat. They
are connected with glands in the neighbourhood, and after having com-
municated by anastomoses with the lymphatics of the lungs, at and near
the roots of those organs, they terminate in the thoracic duct.
The lymphatics of the thymus gland are numerous. According to Astley
Cooper, two large vessels proceed downwards from them on each cornu, and
terminate in the jugular veins by one or more orifices on each side.
(Anatomy of the Thymus Gland, p. 14.)
LYMPHATICS OF THE UPPER LIMB,
AND OF THE BREAST AND BACK.
In the upper limb, as in the lower, the lymphatics are arranged in a deep
and a superficial set. These two sets of vessels, together with the lymphatics
of the surface of the greater part of the back, and those of the mamma and
pectoral muscles, converge to the axillary glands.
The lymphatic glands found in the upper limb below the axilla are neither
large nor numerous ; a few, however, are found in the course of the brachial
artery, and even of the arteries of the forearm ; and one or more small glands
are found in connection with the superficial lymphatics, lying near the
commencement of the basilic vein, a little above and in front of the inner
condyle of the humerus.
The axillary glands are generally ten or twelve in number : they vary,
however, considerably in their number as well as in their size, in different in-
dividuals ; they are mostly placed along the axillary vessels, the lower member
of this group receiving the lymphatics which ascend from the limb ; but a few
lie further forwards on the serratus magnus near the external mammary
artery, and beneath the pectoral muscles, and receive lymphatics from the
mamma and muscular walls of the chest ; while others incline downwards at
the posterior boundary of the axilla, and are joined by the lymphatics from
the back.
From the glands of the axilla efferent lymphatic vessels, fewer in number,
but larger in size than the afferent vessels, proceed along the course of the
subclavian artery, in some parts twining round it. From the top of the
thorax they ascend into the neck, close to the subclavian vein, and terminate,
those of the left side in the thoracic duct, those of the right side
THE ABSORBENTS.
Fig. 337.
in the right lymphatic duct.
Sometimes they unite into a
single trunk, which opens sepa-
rately into the subclavian vein
near its termination.
The superficial lymphatics of
the upper limb are usually de-
scribed as forming two divisions
corresponding with the super-
ficial veins on the outer and
inner borders. On the front of
the limb they arise from an arch
formed in the palm of the hand
by the union of two lymphatic
vessels proceeding from each
finger : becoming more numerous
in the forearm, they are found
thickly set over its surface,
whence they pass upwards in
the arm ; the inner vessels in
Fig. 337. SUPERFICIAL LYMPHATICS OF THE BREAST,
SHOULDER, AND UPPER LIMB, FROM BEFORE (after
Mascagni).
The lymphatics are represented as lying upon the deep
fascia.
a, placed on the clavicle, points to the external jugular
vein ; b, the cephalic vein; c, the basilic vein ; d, radial ;
e, median ; /, ulnar vein ; g, great pectoral muscle cut
and turned outwards ; 1, superficial lymphatic vessels
and glands above the clavicle ; 2, those below the clavicle
partly joining the foregoing and dipping into the triangular
space between the deltoid and pectoral muscles ; 3,
lymphatic vessels and glands placed along the border of
the axilla and great pectoral muscle ; 4, upper brachial
and axillary glands and vessels ; 5, two small glands
placed near the bend of the arm ; 6, radial lymphatic
vessels ; 7, ulnar lymphatic vessels ; 8, 8, palmar arch
of lymphatics ; 9, 9', outer and inner sets of vessels.
a straight direction, and those placed further
outwards inclining gradually inwards over the
biceps muscle to reach the axillary glands. On
the back of the hand also tAvo lymphatics pro-
ceed from each finger ; and from the copious
network on the back of the forearm vessels pass
over the radial margin, and in greater number
round the ulriar side to join those in front. The
lymphatic vessels in the front of the upper arm
are also joined by others which pass round each
side of the limb, and by some which descend
from the shoulder.
The deep lymphatics of the upper limb corre-
spond with the deep blood-vessels. In the fore-
arm they consist, therefore, of three sets, as-
sociated respectively with the radial, ulnar,
and interosseous arteries and veins. In
LYMPHATICS OF THE HEAD AND NECK. 499
their progress upwards some of them have communication near the wrist
with the superficial lymphatics ; and some of them enter the glands which
lie by the side of the brachial artery near the bend of the elbow. They all
terminate in the glands of the axilla.
The lymphatics of the chest consist of branches running under cover of
the pectoral muscles, and of subcutaneous vessels, twigs of which are con-
tinued from those on the abdominal wall as low as the umbilicus, decus-
sating with the vessels which converge to the inguinal glands.
The superficial lymphatics of the back converge to the axillary glands from
its various regions ; from the neck over the surface of the trapezius
muscle, from the posterior part of the deltoid, and from the whole dorsal
and lumbar regions as low as the crest of the ilium ; the branches decus-
sating inferiorly with vessels leading to the inguinal glands, and likewise
crossing the middle line so as to decussate with branches of the opposite
side. (Mascagni, Tab. xxii., xxiii. , xxiv.)
LYMPHATICS OF THE HEAD AND NECK.
The lymphatic glands found on different parts of the head and face are
few and small : those in the neck, on the contrary, are comparatively very
large and numerous.
The cervical glands are placed chiefly on the sides of the neck, and
are divisible into a superficial and a deep series. Of the former, some lie
beneath the base of the inferior maxillary bone ; the remainder, arranged
along the course of the external jugular vein, exist in greatest number in
the angular space behind the lower end of the sterno-mastoid muscle, where
that vein enters the subclavian vein : at this point the cervical glands
approach and are connected with the glands of the axilla. The deep
cervical glands are placed along the carotid artery and internal jugular
vein, extending downwards on the sheath of those vessels as far as the
thorax.
The lymphatic vessels of the cranium and face, together with those of
the tongue, pharynx, larynx and other parts of the neck, pass into the
cervical glands. From these efferent vessels issue, which progressively
diminish in number during their descent, and unite into two trunks, of
which the left one ends in the thoracic duct, and the other in the right
lymphatic duct : sometimes, however, the main cervical lymphatic vessel
terminates separately at the junction of the subclavian and internal jugular
veins, or in one of those veins immediately before their union.
The lymphatics of the cranium consist of a temporal and an occipital set.
Those of the temporal set descend in front of the ear, some of the vessels
passing through one or two glands usually found near the zygoma, whilst
others enter those situated on the parotid gland ; all of them terminate in the
lymphatic glands of the neck. The cranial lymphatics of the occipital set,
accompanying the occipital artery, descend to the glands situated behind
the ear, on and near the mastoid process of the temporal bone, and
hence join the superficial lymphatics of the neck.
Within the cranial cavity, lymphatic vessels have been demonstrated in
the pia mater and in the arachnoid membrane. None have been traced
in the dura mater, nor have they been shown in the substance of the brain.
The trunks of those derived from the pia mater pass out of the skull with
the veins.
The superficial lymphatics of the face, more numerous than those of the
500
THE ABSORBENTS.
cranium, descend obliquely in the course of the facial vein, and join the
submaxillary glands, from six to ten in number, which are placed beneath the
Fig. 338.
Fig. 338. PRINCIPAL LYMPHATIC VESSELS AND GLANDS OP THE HEAD AND NECK
ON THE RIGHT SIDE (after Bourgery in part).
The inner half of the right clavicle and part of the sternum have been removed so as
to expose the arch of the aorta, and the innominate artery and veins : the posterior belly
of the omo-hyoid muscle is removed; and the sterno-mastoid, sterno-hyoid, and sterno-
thyroid muscles, and a part of the external jugular vein have been divided so as to expose
the deeper parts.
a, the right innominate vein at the place where it is joined by the principal lymphatic
trunk ; a', the left vein ; b, arch of the aorta ; c, common carotid artery ; d, thyroid
gland crossed by the anterior jugular vein ; e, cut surface of the sternum ; /, outer part
of the clavicle ; 1, submaxillary lymphatic vessels ; 1', sublingual ; 2, temporal, facial and
parotid ; 3, occipital and posterior auricular ; 4, deep or descending cervical close to the
great vessels ; 5, transverse cervical ; 6, deep pectoral and axillary ; 7, on the vena cava
superior, some of the right mediastinal ; 8, on the innominate artery, some of the deeper
cardiac and bronchial ; to these last are seen descending some of the lymphatics from the
thyroid gland and lower part of the neck.
base of the lower maxillary bone ; a few of them in their descent pass
through some glands situated on the buccinator muscle. The deep lym-
phatics of the face, derived from those of the temporal fossa and the
cavities of the nose, mouth, and orbit, proceed outwards in the course
of the internal maxillary vein ; and, having reached the angle of the jaw,
they enter the glands in that neighbourhood.
XnTE. 501*
NOTE TO PAGE 180.
At the page indicated, the action of the straight muscles of the eye-ball has been
shortly described, but no notice is taken of that of the oblique muscles. The omission
was deemed advisable, from the difficulty of giving within a short space an intelli-
gible account of a matter still involved in uncertainty; but the attention of the
Editors having been drawn to it as a defect which it was desirable to remedy, they
have endeavoured to do so in the present note.
The motions of the eye-ball take place round three axes, viz., a transverse, a vertical,
and an antero-postehor. Those round the first two axes are effected more imme-
diately by the straight muscles, which have also the power by the successive or con-
current contraction of different ones among them to direct the pupil to all the points
of space within the cone by which the movements of direction are limited. The
movements of rotation on an antero-posterior axis are no doubt effected chiefly by
the oblique muscles ; but it is still doubtful to what extent and in what circumstances
these movements occur.
By the experiment of Bonders, viz., that of turning the head downwards to the side
after an ocular spectrum of a bright vertical line has been fixed in the eyes, and which
it is easy to repeat with the same result, it is ascertained that the eyes turn accurately
with the head, and are not balanced in the vertical position by the rotary action of
the oblique muscles, as was supposed by Hueck and others. The rotation of the eyes
by the oblique muscles must therefore have some other object.
When the optic axis is directed straight forwards, the simple action of the superior
oblique muscle (as ascertained by experiment on the dead subject) is to direct the
pupil with some degree of rotation downwards and outwards; that of the inferior
oblique to produce a similar movement in an upward and outward direction ; and no
doubt both muscles acting in concert on one eye, while the optic axis is still straight
forward or is somewhat everted, may produce a horizontal outward movement of the
pupil. But if on the other hand the eye is turned forcibly inwards, it is conceivable
that, as then the points of insertion of the oblique muscles will be brought further
forward, these muscles may along with other movements give an inward direction to
the pupil.
The most important actions of the oblique muscles probably take place in com-
bination with one or more of the straight muscles. Careful observations ap-
pear to have proved that the recti muscles are incapable of altering materially the
form of the eye-ball, or of diminishing its distance from the back of the orbit ; and it
is equally certain that the oblique muscles have little or no effect as antagonists in
drawing forward the eye-ball. It would appear, however, that while the external and
internal recti muscles act exactly in the horizontal plane between them, so as not to
produce any upward or downward direction along with their horizontal movements,
the superior and inferior recti, from the obliquity of the line in which they proceed
forwards towards their insertion, have both a tendency to direct the eye somewhat
inwards. It seems very probable, according to the views stated in the papers referred
to below, that the inward direction produced by the superior or inferior rectus may
be corrected by the combination of the action of different oblique muscles with that
of one or other of the recti muscles; i. e., the inferior oblique with the superior
rectuB, and the superior oblique with the inferior rectus. In a similar manner the
oblique muscles may also counterbalance an increased inward direction given by the
internal rectus, and increase an outward direction given by the external rectus.
On the whole, it seems probable that the oblique muscles have the effect of main-
taining accurately the parallelism of the two eyes by balancing the action of the
several sets of straight muscles.
See for an account of this subject and its application to the study of different forms
of paralysis of the muscles of the eye, a paper by Dr. John S. Wells in the Ophthalmic
Hospital Eeports, &c., vol. ii. 1859-60, p. 44; and a paper by Von Graefe on the
Physiology and Pathology of the Oblique Muscles of the Eye in the Archiv fur
Ophthalmologie, vol. i. part i. p. 1.
DATE DUE SLIP
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