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sSTSTEM OF ANATOMY

FOR THE USE OF

STUDENTS OF MEDICINE^

BY CASPAR.WISTAR, M.D.,

LATE PKOFESSOR OF ANATOMY IN \HE UNIVERSITY OF PENNSYLVANIA.

WITH NOTES AND ADDITIONS,
BY WILLIAM E. HORNER, M.D.,

PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA.

NINTH EDITION.
ENTIRELY REMODELED,

AXD ILLUSTRATED BY MORE THAN TWO HUNDRED ENGRAVLNGS.

BY J. PANCOAST, M. D.,

PROFESSOR OF GENERAL DESCRIPTIVE AND SURGICAL ANATOMY IX JEFFERSON MEDICAL

COLLEGE OF PHILADELPHIA, LECTURER ON CLINICAL SURGERY, FELLOW

OF THE PHILADELPHIA COLLEGE OF PHYSICIANS, ETC., ETC.

IN TWO VOLUMES.
VOL. II.

PHILADELPHIA:

THOMAS, COWPERTHWAIT & CO,

1846.

Entered, according to the Act of Congress, in llie year 1843, by

THOMAS, COWPERTHWAIT & CO.,

In the Clerk's Office of the District Court of the Eastern District of Pennsylvania.

GREENFIELD, MASS.
MEKRIAM AND MIRICK, PRINTERS.

CONTENTS OF VOL, II.

PART VII.

OF THE ABDOMEN.

CHAPTER I.

GENERAL VIEW OF THE ABDOMEN AND PELVIS, AND THEIR CONTENTS. GENE-
RAL ANATOMY OF THE SEROUS TISSUES. OF TH^ PERITONEUM.

Of the Abdomen, ------ 13

Regions of the Abdomen, - - • - - 16

Pelvic Viscera, ----... ig

General Anatomy of Serous Membranes, - - - - 20

Of the Peritoneum and its reflections, - - - - 22

CHAPTER H.

GENERAL STRUCTURE OF THE ALIMENTARY CANAL. OF THE CESOPHAGUS,
STOMACH, INTESTINES, ETC.

General Structure, ------ 27

Of the CEsophagus, - - - - - - -28

Stomach, - - - - - - - 31

Intestines, - - - - - - -41

Villous Coat of, - - - - 42

Villi of, 43

Division of, - - - - - 45

Small Intestines, - - - - - - 46

Duodenum, ----.. 47

Jejunum and Ileum, - - - - - - 48

Mesentery, - - - - - - 51

Great Intestines, - - - - - - 53

Ccecum, ------.54

Colon, - - - - - - - 55

Rectum, ----.-.53

Absorbents aad Nerves of Intestines, - - - 60

1*

VI CONTENTS.

Of th& Omentum, - - - - - - 61

General Anatomy of Mucous Membranes, - - - 63

Villi, 66

Blood-Yessels and Nerves of Mucous Membranes, - - 68

Absorbent Vessels, ----- 69

Nerves, - - - - - - -70

Follicles and Glands, - - - - - 70

Lieberkubn's Follicles, - - - - - 71

Glandulee Solitarise, _ - . . _ 74

Glandulae Agminatae, - - - - - 75

General Anatomy of Glandular Tissue, - - - 77

Capillary Blood- Vessels of Glands, - - - - 84

CHAPTER III.

OF THE LIVER, PANCREAS, AND SPLEEN.

Of the Liver, - -- - - - - 87

Lobes of the Liver, - - - - - - 88

Ligaments of the Liver, ----- 89

Hepatic Vessels, - - - - - - 91

Hepatic Duct, ------ 92

Hepatic Nerves, - - - - - - 95

Acini of the Liver, ----- 97

Pancreas, ----... 105

Spleen, -----.. loT

CHAPTER IV.

OF THE URINARY ORGANS AND GLANDULE RENALES.

Of the Glandulae Renales, - - - - - -117

Kidneys, - - - - - - 119

Ureters, - - - - - - - 126

Urinary Bladder, ------ 127

Sphincter of the Bladder, - - - - - 131

CHAPTER V.

OF THE MALE ORGANS OF GENERATION.

Of the Testicles and their Appendages, - - - - 138

Scrotum, --..--. 139

Dartos, ------- 140

Spermatic Cord, - - - - - -141

CONTENTS. VU

Of the Tunica Vaginalis Testis, - - - - 144

Tunica Albuginea, ------ 145

Epididymis, -___-- 146

Body of the Testicle, 146

Ducts of Testicle, ----- 149

Vas Deferens, ------ 153

Vesiculas Seminales, ----- 154

Prostate Gland, - - - - - -156

Cowper's Glands, ---_-. 158

Of the Penis, -..---- 158

Corpora Cavernosa, ----- 159

Urethra, - - - - - - -161

Canal of the Urethra, ----- 164

Integuments of the Penis, ----- 170

Fascia of the Perineum, - - - - 172

General Anatomy of Erectile Tissue, _ - - 178

CHAPTER VI.

OF THE FEMALE ORGANS OF GENERATION.

Of the External parts of Generation, - - - - 183

Vaginae, --.---. I86

Uterus, ------- 189

Fallopian Tubes, - - - - - - 193

Round Ligaments, . - - - _ 195

Ovaries, ------- 195

Vessels of Uterus, - - - - - 197

Bladder and Urethra, ----- 199

Changes induced in the Uterus by Pregnancy, - - 200

Abdomen of the Foetus, ----- 202

Umbilical Vessels, ----- 204

PART VIII.

GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.
CHAPTER Vn.

BLOOD-VESSELS IN GENERAL. GENERAL ANATOMY OF THE ARTERIAL SYSTEM.
OF THE HEART. OF THE VENOUS SYSTEM.

Of the Blood-Vessels in general, ----- 207
General Anatomy of the Arterial System, - - 209

VIU CONTENTS.

Of the Structure of the Arteries, - - - - - 210

Position of the Heart, - - - - - 216

Dimensions of the Heart, - - - . . 217

Form of the Arteries, - - - - - 221

Capillaries, ----.._ 223

Action of the Heart and Arteries, . . - 226

Pulse, - - - - - - - 228

Veins, ---.-.. 229
Blood, ------- 232

Serum, ------- 233

Crassamentum, ------ 234

Coloring Matter, ----- 235

Globules of Blood, - - - - - - 236

Globules of Chyle, ----- 238

CHAPTER YHI.

DISTRIBUTION OF THE ARTERIES.

Of the Aorta and its Branches, - - - - . 240

Fore and Back Views of the Heart, - - - - 241

Common Carotid, ------. 246

External Carotid and its Branches, - - - . 247

Explanation of the Plate of the Aortic System, - - . 344

Of the Internal Carotid and its Branches, - - - 259

Subclavian and its Branches, - - - - 264

Explanation of Plate of the Arteries of the Brain, - - 268

Of the Axillary and its Branches, - - - - - 271

Explanation of Plate of the Arteries of the Arm, - - 278

Of the Branches sent off from the Aorta below its Arch, - - 281

in the Cavity of the Thorax, - - - 281

in the Cavity of the Abdomen, ... 283

Explanation of Plate, -.--.. 284

The Primitive Iliacs, -.-.._ 293

Of the Internal Iliac and its Branches, - - . . 294

External Iliac and its Branches, - - - . 299

Femoral Artery and its Branches, .. - . 301

Popliteal and its Branches, - - - - . 303

Explanation of Plate of the Arteries of the Lower Extremities, 308

CHAPTER IX.

OF THE PARTICULAR DISTRIBUTION OF THE VEINS.

Of the Particular Distribution of the Veins, - - - 310

Coronary Veins of the Heart, - - - - 311

CONTENTS. IX

Of the Superior Cava, - - - - - - 312

Vena Azygos, ___--- 312

Intercostal Veins, . . _ . - 314

Internal Jugular, ------ 316

External Jugular, - _ _ - - 318

Veins of the Arm, ------ 319

Inferior Vena Cava, and the Veins connected with it, - 322

Veins of the Lower Extremity, . . - - 326

Pulmonary Arteries and Veins, - - - - 329

PART IX.

GENERAL ANATOMY OF THE ABSORBENT SYSTEM.

General Anatomy of the Absorbent System, . . - 332

Comparison between Absorbents and Veins, - - - 334

Origin of Absorbents, ------ 337

Termination of Absorbents, ----- 346

Of the Chyle, 347

Lymph, _._--- 349

Comparison between Chyle and Lymph, - - - - 349

CHAPTER X.

ABSORBENTS OF THE LOWER EXTREMITIES, ABDOMEN AND THORAX.

Of the Absorbents of the Lower Extremities, - - - 351

Absorbents of the Abdomen and Thorax, - - - 355

Thoracic Duct, - - - - - - 360

CHAPTER XL

ABSORBENTS OF THE HEAD AND NECK, UPPER EXTREMITIES, AND UPPER
PART OF THE TRUNK OF THE BODY.

Of the Absorbents of the Head and Neck, - - - - 364

Absorbents of the Arm and upper part of the Trunk, - 365

Brachio-Cephalic Trunk, ----- 367

CONTENTS.

PART X.

OF THE BRAIN AND SPINAL MARROW— OF THE EYE AND
THE EAR.

CHAPTER XII.

OF THE BRAIN.

Of the Membranes of the Brain, _ . _ - 371

Cerebrum, ------- 378

Ventricles, -.--., 38I

Cerebellum, ------- 388

Basis of the Brain, and Nerves which proceed from it, - 389

CHAPTER XIH.

OF THE SPINAL MARROW.

Of the Spinal Marrow, -

Ligamentum Denticulatum,
Vessels of Spinal Marrow,

394
395
396

CHAPTER XIV.

OF THE EYE.

Of the parts auxiliary to the Eye,

Palpebrae, - - -

Lachr}Tnal Gland,
Lachrymal Sac and Duct,
Tensor Tarsi, - - .

Ball of the Eye,

Sclerotica, - - -

Cornea, _ - -

Choroid, - - - -

Iris, - - - -

Ciliary Body and Ciliary Processes,
Retina, - - -

Spot of Soemmering,
Tunica Jacobi,
Vitreous Humor,
Crystalline Humor or Lens,
Aqueous Humor,

397
398
402
405
407
408
410
412
415
420
428
430
433
436
437
441
445

CONTENTS.

CHAPTER XV.

OF THE EAR.

Of the External Ear, - - - - - - 449

Cavity of the Tympanum, _ _ . - 453

Membrana Tympani, - - - - - 456

Eustachian Tube, ----- 457

Mastoid Cells, 459

Bones of the Ear, - - - - - 461

Muscles of the Bones of the Ear, - - - - 462

Chorda Tympani, - . . - - 463

Labyrinth, ------- 465

Vestibule, ------ 466

Cochlea, ------- 466

Semicircular Canals, ----- 468

Contents of the Labyrinth, ----- 469

Auditory Nerve, ------ 470

Jacobson's Nervous Anastomosis, ----- 476

The Aqueduct, ------- 479

PART XL

OF THE NERVES.

Structure of the Nerves, ------ 481

Nerves of the Brain, ------ 484

First pair, _ - - - - 485

Second pair, ----- 486

Third pair, 487

Fourth pair, ----- 487

Fifth pair, 488

Sixth pair, 496

Seventh pair, ----- 496

Eighth pair, 499

Ninth pair, ----- 505

Of the Cervical Nerves, ----- 507

Nerves of the Diaphragm, ----- 510

Brachial Plexus, - - - - - 511

Nerves of the Arm, ------ 512

Dorsal Nerves, - - - - - 517

Lumbar Nerves, ------ 518

Sacral Nerves, ----- 523

Xn CONTENTS.

Of the Nerves of the Lower Extremity, . _ _ 525

Great Sympathetic Nerve, ----- 526

Cranial Ganglia, ----- 530

Cardiac Nerves, _--... 535

Plexus, ----- 53G

Splancnic Nerves, ------ 537

Solar Plexus, ------ 538

CHAPTER XYI.

GENERAL ANATOMY OF THE NERVOUS SYSTEM.

Of the Cineritious Neurine, ----- 543

Medullary Neurine, ----- 545

Neurilema, ------ 547

Functional Divisions of Nervous Substance, - - 549

Ganglia, ------- 551

Commissures, ------ 552

Nerves, ------- 552

CHAPTER XVH.

OF THE SPECIAL ANATOMY OF THE SPINAL MARROW AND BRAIN, AS DE-
SCRIBED FROM BELOW UPWARDS.

Of the Medulla Spinalis, ----- 558

Nucleus of Spinal Marrow, - - _ _ 56O

Fissure of Spinal Marrow, _ - - _ 551

Roots of the Nerves, - - . _ _ 562

Connexion of Nerves with Cord, - - _ 564

Medulla Oblongata, ----- 567

Corpus Restiforme, ----- 570

Corpus Pyramidale, ----- 571

Corpus Olivare, - - - - - 571

Cerebellum, ------ 573

Pons Varolii, ------ 578

Valve of Vieussens, ----- 580

Cerebrum, - - - - - - 581

Anterior and Posterior Ganglia of the Brain, - - 582

Corpus Callosum, - - - - - 584

Tubercula Quadrigemina, - - - - - 581

Fornix, ------ 585

Infundibulum and Pituitary Gland, - - - - 588

Immediate Origin of the Encephalic Nerves, - - 589

Development of the Fcetal Brain, - - - - 594

Glossary, ------- 603

SYSTEM OF ANATOMY.'

PART VII.

OF THE ABDOMEN.

The lowermost of the two great cavities of the trunk of the
body is called Abdomen. The pelvis may be considered as a
chamber of this cavity, although its structure is very different.

CHAPTER I.

A GENERAL VIEW OF THE ABDOMEN AND PELVIS AND THEIR
CONTENTS. GENERAL ANATOMY OF THE SEROUS MEM-
BRANES. OF THE PERITONEUM.

Of the Abdomen.

This great cavity occupies more than half of the space
enclosed by the ribs, and all the interior of the trunk of the
body below the thorax.

It is bounded above by the diaphragm, which is supported
by the lower ribs ; by a portion of the spine and its adjoining
muscles behind ; and on the front and sides by the various
muscles which occur between the lower margin of the thorax
and the upper margin of the ossa innominata : these bones
contribute, by means of the costae of the ossa ilia to form the
lateral walls. The pelvis forms the lower boundary.

VOL. II. 2

14 CONSTKUCTION OF THE ABDOMEN.

The general figure of this cavity partakes of the figure of
the lower part of the trunk of the body ; with these exceptions
that the diaphragm makes it arched or vaulted above, that the
spine and psoae muscles, &c., are rather prominent on the pos-
terior surface, and that the lower part corresponds with the
costae of the ossa ilia and with the pelvis.

To acquire a precise idea of this cavity, it is necessary first
to study the bones concerned in its structure in their natural
situation in the skeleton ; and then the muscles, which form so
large a part of it.

The arrangement of the tendons of some of these muscles,
with a view to complete the cavity, is particularly interesting ;
as that of the external oblique where it forms the crural arch.*
The ligaments of the pelvis and the levatores ani muscles, as
they also contribute to the formation of the cavity, and have
an influence upon its figure, should likewise be attended to.

In the walls of the cavity, thus constructed, there are many
foramina, by which the viscera and other contained parts com-
municate externally ; but few of them pass directly into the
cavity ; for, like the thorax, there are no vacuities in it, exterior
to the contained organs.

Three of these foramina are in the diaphragm. One for the
transmission of the aorta, another for the vena cava, and a
third for the oesophagus. Below, there is an aperture at each of
the crural arches, for the transmission of the great femoral
vessels ; in each of the ligamentous membranes which closes
the foramen thyroideum, for the obturator vessels and nerve ;
and at the sacro-sciatic notches, for nerves and blood-vessels.

There are also two apertures at the bottom of the pelvis, for
the orifice of the rectum and of the urethra. In the tendons of
the external oblique muscles are two orifices, covered by the
integuments, for the spermatic cords ; and, in the foetal state,
one for the umbilical cord.

The apertures in the tendons, and under their edges, for the

* See the account of this tendon, vol. i. in the description of the " Obliquus
Descendens Externus."

CONTENTS OF THE ABDOMEN. 15

transmission of the spermatic cords, blood-vessels, &c., are
not to be considered as simple perforations made abruptly ;
but the edges of these foramina are formed by tendinous mem-
branes turned inwards, and continued so as to compose a cylin-
drical tube, which becomes gradually so thin that it cannot be
readily distinguished from the cellular membrane with which
it is connected.* The blood-vessels, &c., pass along this tube
before they go through the apertures.

It is evident from the construction of this cavity, that it is
essentially different from the thorax. It has no power of spon-
taneous dilation whatever: it yields passively to the distension
of the stomach and intestines, during deglutition, and when air
is extricated from the aliment, &c. ; but it is particularly cal-
culated for compressing its contents by the contraction of the
muscles which compose it. The diminution of its capacity,
which is thus effected, not only takes place to a great degree,
but occasionally with great force. The diaphragm and the
abdominal muscles may be considered in some measure as
antagonists of each other. When the diaphragm descends, if
the abdominal muscles are passive, they are distended by the
contents of the abdomen, which are forcibly pressed from
above : but if the abdominal muscles act at the same time, an
effort to diminish the cavity in every direction takes place,
and the contained parts are compressed with more or less
force according to the exertion made. This will be very evi-
dent upon examining the situation of the diaphragm and of
the abdominal muscles. When their force is considered, it will
also be very obvious that the various outlets of the cavity are
constructed most advantageously ; otherwise hernia or protru-
sion of its contents would be a daily occurrence.

The abdomen contains, 1st, The Stomach and the whole
Intestinal Tube, consisting of the small and the great intestines.

2d. The Assisting Chylopoietic Viscera, — the Liver, the
Pancreas, and the Spleen.

* The student of anatomy, when engaged with this subject, will be gratified
by the examination of Sir Astley Cooper's plates relating to hernise.

16 REGIONS OF THE ABDOMEN.

3d. The Urinary Organs, — the Kidneys, the Ureters, and
the Bladder. To which should be added the Glandulae Renales.

4th. The Organs of Generation in part : those of the
female sex being almost wholly included in the pelvis ; and
those of the male being situated partly within and partly with-
out it.

5th. The Peritoneum and its various processes. The Mes-
entery, Omentum, &c.

6th. A portion of the Aorta, and almost the whole of the
Inferior Vena Cava, and their great ramifications ; with such
of their branches as are appropriated to the Viscera of the
Abdomen and Pelvis.

7th. Those "portions of the Par Vagum and Intercostal
Nerves which are appropriated to the cavity ; and portions of
some of the nerves destined to the lower extremities.

8th. The lower part of the Thoracic Duct, or the Great
Trunk of the Absorbent System, with the large branches that
compose it, and the glands connected with them : and also
those absorbent vessels called Lacteals,znd their glands.

As the cavity of the abdomen has no natural divisions,
anatomists have divided it by imaginary lines into various
regions, with a view to precision in their accounts of the situ-
ation of the different contained parts. Thus,

They have, very generally, agreed to apply two transverse
lines to form three great divisions ; viz. the Upper, Middle,
and Lower : and they have also agreed that each of these divi-
sions shall be subdivided into three regions.

The three regions of the uppermost division are defined
with some precision. Those on each side, which are called the
Right and Left Hypochondriac regions, occupy the space
immediately within the lower ribs and their cartilages ; while
the middle space, included within the margins of these carti-
lages and a line drawn from the lower edge of the thorax on
one side to that on the other, is denominated the Epigastric
region.

The boundaries of the regions below are less precisely
defined.

REGIONS OF THE ABDOMEN. 17

Many anatomists have fixed the two transverse lines above
mentioned, at an arbitrary distance above and below the
umbilicus : some choosing for this purpose two, inches, and
others a hand's breadth. As these distances will occupy dif-
ferent proportions of the cavity in persons of different stature,
other anatomists, with a view to avoid this inconvenience,
have proposed to connect these lines with certain fixed points of
the skeleton.

It is of importance that the boundaries of these regions
should be fixed, and therefore the proposition of Sabatier may
be adopted ; namely, To draw the upper transverse line from
the most Inferior part of the lower margin of the thorax, on one
side, to the corresponding part on the opposite side ; and the
lower transverse line from the uppermost part of the spine of
one ilium to the same part of the other. These lines will mark
the three great divisions. If, then, two parallel lines are drawn
directly upwards, one from each of the superior anterior spi-
nous processes of the ilium,* until it touches the lower margin
of the thorax, they will divide each of the two lower divisions
of the abdomen into three regions. The centre of the middle
division is the umbilical, and on each side of it is the risht and
left lumbar region. The middle of the lower division is the
hypogastric ; and on each side of it the right and left iliac
region .

It is true that the three middle regions of the abdomen will
be made very small by the vicinity of the transverse lines to
each other ; but the advantages derived from a principle which
is similar in its application to all subjects, fully compensates for
this inconvenience.

There are therefore nine of these regions ; namely, The Epi-
gastric and the two Hypochondriac : the Umbilical, and the two

* Professor Horner makes a more equable division of the cavity of the
abdomen, by drawing the two vertical lines from the anterior inferior spinous
processes of the iliac bones, so as to subdivide each of the three divisions made
by the transverse lines, into three nearly equal parts. Others draw the vertical
Unas from the middle 2, Poupart's ligament. — p.

2*

18 SITUATION OF THE VISCERA IN THE

Lumbar: the Hypogastric, and the two Iliac regions.* And it
should be added, that the space immediately around the end of
the sternum is sometimes called the Scrohiculis Cordis ; and
the space immediately within and above the os pubis, the Regio
Pubis.

These different regions are generally occupied in the follow-
ing manner : The liver fills nearly the whole of the right hypo-
chondriac region, and extends through the upper part of the
epigastric region into the left hypochondriac. The stomach
occupies the principal part of the epigastric region, and a con-
siderable portion of the left hypochondriac. The spleen is also
situated in the left hypochondriac region. That portion of the
intestinal tube, which is composed of small intestines, is gene-
rally found in the umbilical, the hypogastric, and the iliac
regions, and when the bladder is empty, in the pelvis. But
the duodenum, or first of the small intestines, which proceeds
immediately from the stomach, is situated in the epigastric and
umbilical regions. The great intestine commences in or near
the right iliac region, and ascends through the right lumbar to
the right hypochondriac region. It then crosses the abdomen,
passing through the lower part of the epigastric, or upper part
of the umbilical to the left lumbar region ; from this it con-
tinues into the left iliac region, and curves in such a manner
that it finally arrives at the middle of the upper part of the os
sacrum, when it descends into the pelvis, and, partaking of the
curvature of the last mentioned bone, continues to the termina-
tion of the OS coccygis.

In the back part of the epigastric region, and very low down
in it, is situated the pancreas. The kidneys lie in the most pos-
terior parts of the lumbar regions, and from each of them is
continued a tube or duct, called Ureter, that passes into the
pelvis to convey the urine into the bladder. This viscus, in
males, is in contact with the last portion of the great intestine
called the Rectum, and with it occupies almost all the cavity of

* It is lo be observed that the lateral regions of the middle and lower divi-
sions of the abdomen are named differently by different writers.

CAVITY OF THE ABDOMEN. 19

the pelvis ; while in females, the uterus and its appendages are
situated between this intestine and the bladder.

In the posterior part of the abdomen, in contact with the
spine, is the aorta. This great blood-vessel passes from the
thorax between the crura of the diaphragm, and continues down
the spine until it approaches the margin of the pelvis, when it
divides into two great branches called the Iliac Arteries. Each
of these great branches divides again, on the side of the pelvis,
into two ; namely, the External Iliac, which passes under the
crural arch to the thigh, and the Internal Iliac or Hypogastric
which descends into the cavity of the pelvis.

Soon after the arrival of the aorta in the abdomen it gives off
two large branches. The first, which is called the Caliac, is
distributed to the liver, the stomach, and the spleen : the second,
called the Superior Mesenteric, is spent upon the intestines.
Lower down in the abdomen, it also sends off a small branch
for the intestines, called Inferior Mesenteric. Besides these
vessels for the chylopoietic viscera, the aorta sends off a large
branch, called Emulgent, to each kidney.

The inferior or ascending vena cava is situated on the right
of the aorta, in front of the spine. It is formed below by the
union of the iliac veins, and in its progress upwards, it receives
the emulgent veins, which correspond to the arteries of the
kidneys ; but it receives in its course no veins which correspond
directly with the coeliac and mesenteric arteries. The smaller
veins that answer to the branches of these arteries, unite and
form one large vein, which goes to the liver, and' is called
(from the part of that viscus at which it enters,) Veiia Porta-
rum. From the liver three large veins pass into the vena
cava, and deposit there the blood of the vena portarum, after
it has furnished materials for the secretion of bile. The vena
cava, in its passage upwards, is in close contact with the
posterior thick edge of the liver : it often passes along a deep
groove in this edge, and sometimes it is completely surrounded
by the liver in its course. The veins of the liver enter the
vena cava at this place, and of course they are not to be seen
without dissection. Immediately after leaving the liver, the

20 GENERAL ANATOMY OF THE SEROUS MEMBRANES.

vena cava passes through an aperture in the tendinous centre
of the diaphragm to unite itself to the right auricle of the
heart.

General Anatomy of Serous Tissues,

— The serous tissue, is found in every part of the body where
there is an habitual movement of parts upon each other. Its
object appears to be to diminish friction and to facilitate motion,
by the glassy smoothness of the free surfaces which it presents,
and by its pouring out continually a lubrifying liquid between
the surfaces where motion occurs. The serous system consists
of a great number of membranes, forming closed sacs,* which
are adherent by their external surface to the organs which they
line ; — their internal surface is free and smooth, and secretes a
fluid, with which they are in a healthy stale constantly mois-
tened, analogous to the serum of the blood. The adhesion of
the outer surface of the serous tissues to the subjacent parts, is
so intimate in most places, that it has only been within latter
times, by the labors of Bonn, Monro, and Bichat, that their
proper character has been determined. They consist of the
peritoneum, the pleura, the pericardial lining membrane, the
arachnoid of the brain and spinal marrow, the tunica vaginalis
testis, and the synovial capsulesf of the joints and tendons.
The serous membranes are all extremely thin, delicate and of
a transparent whiteness ; they are attached to the parts they
cover by the intermedium of cellular tissue, which in some parts
is long and loose, and in others so short and dense as to be
scarcely discernible and to which they seem to form a simple
serous facing. Hence Bordeu, and Rudolphi were disposed to
consider the serous membranes as a modification of cellular
tissue, formed by the flattening of the cells of the latter.
— Though this is true probably in regard to their ultimate struc-

* The peritoneum of the female, which has the fallopian tube opening into
its cavity, is the only instance of a serous membrane which is not a closed sac,
provided it be admitted that the synovial capsules of the joints cover the artic-
ular cartilages. — p.

f The synovial membranes were considered by Bichat as forming a distinct
tissue, which he named synovial. — p.

GENERAL ANATOMY OF THE SEROUS MEMBRANES. 21

ture, yet since they exist, as Bichat has shown us, as distinct
membranes in the early periods of foetal life, and as their dis-
eases exhibit peculiar phenomena, they deserve to rank among
the elementary tissues of the body. Some of the serous mem-
branes consist merely of a simple bag of greater or less size —
some line cavities which are very irregular in surface and
shape — and others, like the pleura and peritoneum, are reflect-
ed over the inner face of the viscera, like the internal fold of
the double night-cap over the head, and presenting a very
complicated arrangement, so that the viscera which the mem-
brane lines are necessarily left upon its outer side. All the
vessels which enter these viscera, pass between the two layers
that form the roots of the folds by which they are embraced.
(See fig. 133, p. 24.)

— In the healthy state the serous membranes are perfectly white
and insensible ; and when in a state of inflammation, the appa-
rent redness of the membrane is frequently owing to the injection
of the sub-serous cellular tissue. Nevertheless they contain a
vast number of serous capillary vessels, which Ruysch suc-
ceeded in injecting in such abundance, as to be led to think
they were composed chiefly of these vessels. Mascagni was
equally successful in filling their lymphatics, and considered
these vessels the principal elements in the composition of serous
tissues. Both, therefore, exist in great numbers, and woven
together with some intermediate connecting fibres like those of
the cellular tissue, constitute these membranes. This, too, is
the ultimate composition of cellular tissue as proved by the
recent researches of Miiller and Treviranus. (See vol. i. p. 406.)
The serous membranes are said to yield gelatine by boiling,
and in this respect also they agree with the cellular membrane.
The serous capillaries pour out a lubricating serous fluid, (called
halitns from its vapory condition during life, and which con-
denses as the body cools after death,) by a process called
exhalation, which we do not fully understand, and which the
absorbents gradually remove during health, so as to prevent
its accumulation. But when the usual healthy balance of action
between them is disturbed, either by too copious exhalation,

22 THE PERITONEUM.

or by languid absorption, dropsy may take place in any one of
what are called the serous cavities of the body. There is not
in fact, though the term is in general use, any cavity or unoc-
cupied space in the interior of any of these membranes. In
the healthy state, organ is in contact with organ, and the
reflected membranes with which they are lined, slide over those
which line the parietes of the so called cavities. And when
the area of a joint is suddenly enlarged, as those of the fingers
may be by pulling at the phalanges, the fluid within becomes
rarified to fill the vacuum, and is the cause by its sudden con-
densation of the snapping noise heard when the bones return in
contact. The same phenomenon is sometimes observed in mas-
tication, produced by the relaxation of the ligaments of the
temporo-maxillary articulation.

— Though no nerves have been traced satisfactorily to the
serous membranes, and they appear to possess little or no sen-
sation in a physiological state, they become exquisitely sensitive
when suddenly inflamed, as in pleuritis. The free polished
surface of the serous membranes is shown by the microscope
to be covered with a very delicate pavemented or tesselated
epithelium. In no other part of the human body, according to
Henle, but the ventricles of the brain, has the epithelium of
serous membranes been found provided with cilia. —

Of the Peritoneum.

The abdomen, constructed and occupied as above described,
is lined by a thin firm membrane called Peritoneum, which
is extremely smooth on its internal surface, and is imme-
diately connected with the cellular substance exterior to
it. This membrane adheres closely to the anterior, lateral
and superior portions of the surface of the abdomen ; and is
extended from the posterior surface so as to cover more or less
completely, the viscera of the cavity.

Those viscera which are in close contact with the posterior
surface of the abdomen, as some portions of the large intestine,
are covered only on their anterior surfaces, and are fixed in

THE PERITONEUM. 23

their precise situation by the peritoneum ; which extends from
them to the contiguous surface of the cavity, and adheres where
it is in contact, so as to produce this effect.

Fig. 132.*

Other viscera, which are not in close contact, but movable
to a distance from the posterior surface of the abdomen, are
covered by this membrane, which is extended to them from
the surface ; and this extended portion forms an important part
of the connexion between the viscus and the cavity in which
it lies. This connecting part is called Mesentery, when it thus
passes to the small intestines ; Mesocolon, when it goes to the
colon, one of the larger intestines ; and Ligament, when it passes
to some of the other viscera.

The peritoneum is a complete but empty sac, which is fixed
in the abdomen anterior to the viscera. The anterior portion
of this sac forms the lining to the anterior and lateral parts of
the surface of the abdomen : the posterior portion covers the
viscera, and forms the mesentery, mesocolon, and ligaments
above described.

It necessarily follows that the mesentery and the other simi-
lar processes are mere plaits or folds of the sac, which invests
the viscera ; and that they must consist of two lamina ; and as
the blood-vessels, nerves, and absorbents, are all posterior to

* Diagram representing a transverse section of the abdomen, in the lumbar
region, a, Umbilicus, b, A lumbar vertebra, c, Kidneys, d, Ascending
colon, e, Small intestine. /, Descending colon, g, Inferior vena cava.
ft, Aorta, i, Left mesocolon, k, Mesentery. I, Right mesocolon.

24

THE PERITONEUM.

the peritoneum, they naturally pass between these lanoina of
the mesentery.

Some of the viscera are much more completely invested with
the peritoneum than others. The stomach, liver, and spleen are
almost completely surrounded by it; and it is said to form a
coat for each of these viscera. That portion of the smaller
intestinal tube, which is called jejunum and ileum, and the
transverse portion of the large intestine, called the arch of the

Fig. 133.*

colon, are invested by it in
the same way. But a con-
siderable portion of the du-
odenum and the pancreas
is behind it. The lateral
portions of the colon are in
close contact with the pos-
terior surface of the abdo-
men, and the peritoneum
only covers that portion of
their surfaces which looks
anteriorly towards the cavi-
a ty of the abdomen, and is
not in contact with its pos-
terior surface.

The urinary organs are
not much connected with
the peritoneum. The kid-
neys appear exterior to it,
and behind it : the bladder
of urine is below it, and has
but a partial covering from
it, on its upper portion.

* Fig. 133 is a diagram, illustrating the reflections of the peritoneum, a,
Umbilicus, b, b, Diaphragm, c, Liver, d, Stomach, e, Transverse colon.
/, Duodenum, g, Pancreas, h, Small intestines, i, Vertebral column, k,
Promontory of the sacrum. I, Rectum, m, Uterus, n, Bladder, o, Symphysis
pubis, p, Coronary ligament of the liver, q, Omentum minus or hepatico-
gastricum. r, Omentum majus, or gastro-colicum. s, Transverse mesocolon.
t, Sac of the omentum majus. u, Mesentery. — p.

THE PERITONEUM. 25

The peritoneum, which covers the stomach, is extended from
the great curvature of that organ so as to form a large mem-
brane, which descends hke an apron before the intestines. This
process of peritoneum is composed of two lamina, so thin and
delicate as to resemble cellular membrane, which, after extend-
ing downwards to the lower part of the abdomen, are turned
backwards and upwards, and proceed in that direction until
they arrive at the colon, which they enclose, and then continue
to the back of the abdomen, forming the mesocolon. The part
of this process which is between the stomach and the colon, is
called Epiploon or Omentum.

This extension of a membrane, from the surface of a cavity
which it lines, to the external surface of a viscus in that cavity,
is called by some anatomists, "reflection;" and the technical
term rejlected membrane is therefore applied to a membrane
distributed like the peritoneum.

It must be evident that this distribution of the peritoneum is
very complex, and that it is not easy to form an accurate con-
ception of it from description, but it can be readily understood
by demonstration ; therefore no farther account of its arrange-
ment will now be attempted, but each of its processes will be
considered with the organs to which they are particularly
subservient.

That portion of the peritoneum which lines the abdomen,
and covers the viscera, is thin and delicate, but very firm. It
yields to distension, as in pregnancy, ascites, &c., and again
recovers its dimensions. It was formerly thought to be com-
posed of two lamina, but this cannot be proved. The internal
surface of this membrane is very smooth, and highly polished ;
and from it exudes a liquor which is well calculated for lubri-
cation, and barely sufScient to keep the surface moist during
health ; but sometimes it is very abundant, and occasions the
aforesaid disease — ascites. This fluid appears to exude from
the surface of the peritoneum when it is compressed in a living
animal, or one recently dead. It is probably effused from the
extremities of arteries, for an effusion takes place when water is
injected into these vessels.

VOL. II. 3

26 THE PERITONEUM.

The peritoneum abounds with absorbent vessels, and there-
fore possesses the power of absorption to a great degree. This
power may be inferred, not only from the spontaneous removal
of the fluid of ascites, but if milk and water be introduced into
the abdomen of a living animal, through a puncture, it will also
disappear.

The blood-vessels of the peritoneum are derived from those
which supply the neighboring parts. Nerves have not yet
been traced into it, and in a healthy state it has little or no
sensibility.

This membrane supports the viscera of the abdomen in their
proper situations ; it also forms a surface for them and for the
cavities which contain them, so smooth and lubricated, that no
injury can arise from their friction.

The cellular substance, by which the peritoneum is connect-
ed to the contiguous parts, is very different in different places.
It is very short indeed between this membrane and the stomach
and intestines, and also between it and the tendinous centre of
the diaphragm. Between the peritoneum and the muscles
generally, it is much longer. Where it covers the kidneys and
the psoas muscle, it is very lax and yielding. About the kid-
neys a large quantity of adeps very commonly collects in it.
On the psoas muscle it yields with but little resistance to the
passage of pus, or any other effused fluid, as in the case of
psoas abscess.

GENERAL STRUCTUKE OF THE ALIMENTARY CANAL. 27

CHAPTER II.

OF THE GENERAL STRUCTURE OF THE ALIMENTARY CANAL.
OF THE OESOPHAGUS, THE STOMACH, AND THE INTESTINES.

General Structure of the Alimentary Canal.

— This canal, formed by the oesophagus, stomach, and intes-
tines, extends inclusively from the pharynx to the anus. It is
composed throughout, (with the exception of the oesophagus,
the transverse part of the duodenum, and the termination of
the rectum, which wants the serous coat,) of four membranes or
tunics ; an internal mucous coat ; one exterior to this, Jihro-
cellular (or nervous as it was formerly called) ; a third more
external still, which is muscular; and of a fourth investing serous
coat, which is derived from the peritoneum lining the cavity of
the abdomen. There enter also into its composition, mucous
glands, nerves, blood-vessels, and absorbents. The arrangement
of the serous tunic varies in different portions of the canal ; but
its general disposition is such, that it embraces the canal, and
serves as a ligament to connect it to the back and lateral parts
of the abdominal parietes, so as effectually to prevent any entan-
glement or knotting in the folds of the canal, and at the same
time allow it great latitude of motion. It is united to the outer
face of the muscular coat, by cellular tissue. The muscular tunic
is of a pale color, soft, and easily lacerated.
— The muscular tunic consists throughout of two orders of fibres,
a circular which is internal, and a longitudinal which is exter-
nal. The former are not entirely circular, but consist of seg-
ments, which, by their reunion, constitute perfect circles. The
longitudinal do not run the whole length of the tube, but are
interrupted after short courses. Both may be considered as
having their origin and insertion in the fibro-cellular tunic,
which separate them from the mucous membrane. The fibro-

28

THE (ESOPHAGUS.

It is the strongest of all the
Fig. 134*

cellular (cellular or nervous coat,) forms a perfect cylinder,
and is composed of fibres of condensed cellular tissue inter
crossed in different directions,
tunics, and gives to the canal
its greatest power of resisting
internal distension. The nerves
ramify abundantly in this tunic
before they reach the mucous
coat ; hence the organic sufFer-
hicr and often sudden death,
resulting from sudden tympani-
tic distension of the alimentary
canal. The mucous membrane
of the canal is every where
continuous. It is of a reddish
color, soft and spongy in its
consistence, and varies in its
thickness, and in the number
of the villi, follicles, and folds,
which it forms in different portions of the canal. —

Of the (Esophagus.

The OEsophagus is a muscular tube which passes from the
pharynx to the stomach, and is so intimately connected with
the stomach, that it will be advantageous to the student to
attend to its structure immediately before he engages in the
examination of that important organ.

* Fig. 134. The pharynx slit open behind, in order to show the relative
position of the opening of the posterior nares, the velum pendulum palati, the
floor of the mouth, and the opening of the larynx, a, Base of the cranium.
b, Mastoid process of the temporal bone, c, Vertical partition between the
nasal fossce, and upon each side of it, the posterior opening of the nares. d,
Velum pendulum palati, a fleshy appendage to the osseous palate; at its middle
part, projecting downwnrds and backwards is seen the uvula, and on each side
of the uvula, are seen the buccal cavities, e, Base of the tongue. /, Extrem-
it)'' of the OS hyoides ; on the opposite side, this bone is entirely concealed by
the portion of the posterior wall of the pharynx, which is folded outwards, g,
Glottis, or opening of the larynx ; the epiglottis is seen above and in front of
this opening, and is in this figure applied against the base of the tongue. A,
Part of the trachea, i, Commencement of the oesophagus. I; Levator pharyn-
geus muscle. —

THE (ESOPHAGUS. 29

— The commencement of the cavity of the pharynx, from
the base of the cranium, and its position behind the posterior
opening of the cavities of the nose, mouth, and glottis, are
well seen in fig. 134, page 28. Its termination below, and the
commencement of the oesophagus are seen at i. —

The pharynx has been above described* as composed of a
varied stratum of muscular fibres, lined by a membrane which
is continued from the internal surface of the nose and mouth.
From the pharynx the oesophagus passes downwards between
the trachea, and the vertebrae. After the bifurcation of the
trachea, it proceeds in contact with the spine, between the
lamina of the mediastinum to the diaphragm, which it passes
through, and then terminates in the stomach.

The oesophagus is a flexible tube, which, when distended, is
nearly cylindrical. It consists of a muscular coat externally,
and an internal tunic evidently continued from that of the
pharynx. These coats are connected by a cellular substance
called the Nervous Coat,f which is remarkably loose, and
allows them to move considerably upon each other. The
muscular coat, which is very distinguishable from that of the
pharynx, consists of two substantial strata of fibres; the
exterior of which is nearly longitudinal in its direction, and the
interior circular or transverse.

— The longitudinal fibres appear to arise in part from the
posterior face of the cricoid cartilage, between the posterior
crico-arytenoid muscles, and part from the lower end of the
pharynx ; They are disposed regularly around the oesophagus,
and below are manifestly continuous with the longitudinal
muscular fibres of the stomach. The first ring of the circular
fibres, also seems to arise from the cricoid cartilage, and has
been described as the crico-oesophageal muscle. There is no
sphincter, at the junction of the oesophagus with the stomach
as has been asserted by some anatomists.

* See Vol. i. p. 490.

f The nervous coat, is as before observed nothing but a structure of submucous
cellular tissue, which connects the mucous membrane, as the subcutaneous
cellular tissue does the skin to the pans subjacent, and through which the nerves
and blood-vessels ramify, before they spread minutely in the mucous mem-
brane.— F.

3*

30 THE (ESOPHAGUS.

— The muscular coat of the oesophagus is next in thickness to
that of the pharynx, and thicker than that of any other portion
of the alimentary canal. —

The internal coat of the oesophagus, resembling that of the
fauces, is soft and spongy. It is covered with a very delicate
cuticle, which Haller supposed to be too tender to confine the
matter of variolous pustules, as he had never found these
extending into the oesophagus. It is very vascular, and abounds
with the orifices of mucous follicles, from which is constantly
poured out the mucus that is spread over this surface. When
the oesophagus is not distended, many longitudinal plaits are
found in this membrane by the contraction of the circular or
transverse fibres exterior to it. These plaits are calculated to
admit readily of the distension which is requisite in deglutition.
This tunic is continued from the lining membrane of the pha-
rynx above, and terminates below in the villous coat of the
stomach ; from which, however, it is very different.

— The cuticle terminates by an irregularly fringed or fes-
tooned border at the cardiac orifice, where the oesophagus ter-
minates, and is insensibly lost upon the mucous membrane of
the stomach. The mucous membrane of the oesophagus, like
that of the rectum (and unlike that of any other portion of the
alimentary canal,) is united by a very loose cellular tissue to
the inner face of the circular stratum of fibres, so that it may
be withdrawn as a cylindrical tube from the muscular sheath in
which it is contained.

— Experimenters upon living animals have asserted that they
have seen the muscular coat, force by its contraction the mu-
cous membrane downwards into the stomach, so as to cause it to
form a circular tumor, much like that of the mucous membrane
of the rectum in prolapsus ani. —

The blood-vessels of the oesophagus come from the aorta
and those which are in the vicinity. The nerves are derived
from the eighth pair. The lymphatic vessels are very abun-
dant.

In the neck the oesophagus inclines rather to the left of the
middle line. As it proceeds down the back between the lamina

FORM OF THE STOMACH. 31

of the mediaslinum, it preserves the same course to the fourth
dorsal vertebra, when it assumes the middle position and pro-
ceeds downwards, with the aorta to its left, and the pericardium
before it. About the ninth dorsal vertebra it inclines again
rather to the left, and somewhat forward, to arrive at the aper-
ture in the diaphragm through which it passes.

Throughout this course it is connected by cellular membrane
to the contiguous parts ; and this investiture of cellular mem-
brane has been called its External Coat.

While the oesophagus is in the posterior mediastinum it is in
contact with several small absorbent glands, especially when it
first assumes a situation to the right of the aorta. These glands
were formerly believed to be particularly connected with this
tube, but they are now considered as belonging to the absor-
bent system. They are sometimes greatly enlarged.

Of the Stomach.

This most important organ, which occasionally exerts a
powerful influence upon every part of the body, appears very
simple in its structure.

It is a large sac, which is so thin when much inflated, that at
first view it seems membranous, but upon examination is found
to be composed of several lamina or coats, each of a different
structure. It is of considerable length, but incurvated. It is
much larger at one extremity than the other, and changes so
gradually in this respect, that it would appear conical, if it were
straight. It is not, however, strictly conical unless it is greatly
distended ; for when moderately distended, a transverse section
is rather oval than circular. It is, therefore, considered as
having two broad sides or surfaces, and two edges, which are
the curvatures. It has been compared by the anatomists of
different nations to the wind sac of the musical instrument called
the bagpipe.* The orifice in which the oesophagus terminates

* The student ought not to attempt to acquire an idea of the form of the
stomach without demonstration, for a view of one moment will be more
serviceable than a long description.

32 POSITION OF THE STOMACH.

Is at a small distance fi'om its largest extremity, and is called
Cardia. The orifice which communicates with the intestines
is at the termination of its small incurvated extremity, and is
called the Pylorus.

The two ends of the stomach being thus very different in
size, are denominated the great and small extremities. The
two curved portions of the surface are also called the great or
superior and small or inferior curvatures. The two flat portions
of the surface or the broadsides, are called the anterior and
posterior surfaces.

The situation of the stomach in the abdomen is nearly trans-
verse: it lies principally in the left hypochondriac and epigas-
tric regions, immediately below the liver. The great extremity

Ficr. 135.*

* A vertical and longitudinal section of the stomach and duodenum, made in
such a direction as to include the two orifices of the stomach. 1. The oesopha-
gus ; upon its internal surface the plicated arrangement of the cuticular
epithelium is shown. 2. The cardiac orifice of the stomach, around which the
fringed border of the cuticular epithelium is seen. 3. The great end of the
stomach. 4. Its lesser or pyloric end. 5. The lesser curve. 6. The greater
curve. 7. The dilatation at the lesser end of the stomach which received from
Willis the name of antrum of the pylorus. This may be regarded as the rudi-
ment of a second stomach. 8. The rugse of the stomach formed by the mucous
membrane : their longitudinal direction is shown. 9. The Pylorus. 10. The
oblique portion of the duodenum. 11. The descending portion. 12. The pan-
creatic duct, and the ductus communis choledochus close to their termination.
13. The papilla upon which the ducts open. 14. The transverse portion of the
duodenum. 15. The commencement of the jejunum. 16. In the interior of
the duodenum and jejunum, the valvulse conniventes are seen.

SEROUS OR EXTERNAL COAT OF THE STOMACH. 33

of the stomach is in the left hypochondriac region, and the lesser
extremity in the epigastric region under the left lobe of the
liver. The upper orifice, or Cardia, is nearly opposite to the
body of the last dorsal vertebra ; and owing to the curved form
of the stomach, the other orifice or Pylorus, is situated at a
small distance to the right of that bone, and rather lower and
more forward than the cardia : both orifices being in the epigas-
tric region. The position of the stomach is oblique in two
respects ; it inclines in a small degree from above downwards,
from the left to the right ; and it also inclines downwards and
forwards, from behind. Its two orifices are situated obliquely
with respect to each other ; for if the stomach, when placed
with its small curvature upwards, were divided into two equal
parts by a vertical plane passing lengthways through it, they
would be found on different sides of the plane.

As the oesophagus terminates in the stomach immediately
after it has passed through an aperture of the diaphragm, it
is evident that the stomach must be somewhat fixed at that
place ; but it is more movable at its other orifice ; for the
extremity of the duodenum, into which it is continued, is
movable.

The stomach is connected to the concave surface of the liver
by the reflection or continuation of the peritoneum which forms
the lesser omentum. This membrane, after extending over each
surface of the stomach, continues from its great curve in the
form of the large omentum, and connects it to different parts,
especially to the colon. There are likewise folds of the perito-
neum, as it passes from the diaphragm and from the spleen to
the stomach, which appear like ligaments.

Notwithstanding these various connexions, the stomach
undergoes considerable changes in its position. When it is
nearly empty, and the intestines are in the same situation,
its' broad surfaces are presented forwards and backwards ; but
when it is distended, these surfaces are presented obliquely
upwards and downwards, and the great curvature forwards.
When its anterior surface is presented upwards, its orifices

34 SEROUS OR EXTERNAL COAT OF THE STOMACH.

are considerably influenced in their direction, and the oesopha-
gus forms an angle with the plane of the stomach.

The stomach is composed of four dissimilar lamina, which may
be demonstrated by a simple process of dissection.

There is a first coat or external covering continued from the
peritoneum : within this, and connected to it by delicate cellular
substance, is a coat or stratum of muscular fibres : contiguous
to these fibres, internally, is a layer of dense cellular sub-
stance, called a nervous coat; and last is the internal coat
of the stomach, called villous or fungous, from the structure of
its surface.

The external or first coat of the stomach, as has been already
stated, is continued from the concave surface of the liver to the
lesser curve of the stomach in two delicate lamina, which
separate when they approach the stomach, and pass down,
one on each side of it, adhering firmly to it in their course:
at the opposite curve of the stomach they again unite to form
the great omentum. The stomach is therefore closely invested
by the peritoneum on every part of its surface except two
strips, one at the lesser and the other at the greater curvature.
These strips or uncovered places are formed by the separation
of the lamina above mentioned, which includes a triangular
space bounded by the stomach and these two lamina. In these
triangular spaces, at each curvature of the stomach, are situat-
ed the blood-vessels which run along the stomach in those
directions, and also the glands which belong to the absorbent
vessels of this viscus. The peculiar arrangement of the lamina
at this place is particularly calculated to permit the dilatation
of the stomach. When it is dilated, the lamina are in close
contact with its surface, and the blood-vessels being in the
angle formed by the adhesion of the two lamina to each other,
are so likewise: when it contracts, the blood-vessels appear to
recede from it, and the lamina are then applied to each
other.

Where the peritoneum thus forms a coat to the stomach, it
is stronger and thicker than it is between the liver and stomach.
In a recent subject it is very smooth and moist, but so thin

MUSCULAR COAT OF THE STOMACH. 35

that the muscular fibres, blood-vessels, (fee, appear through it.
If it is carefully dissected from the muscular coat, it appears
somewhat flocculent on that surface which adhered to the
muscular fibres. It seems to be most abundantly furnished
with serous vessels ; but it has been asserted by Mascagni and
Soemmering, that a large proportion of its texture consists of
absorbent vessels. The cellular substance which connects this
to the muscular coat, appears no way different from ordinary
cellular membrane.

The Muscular Coat of the stomach has been described very
differently by respectable anatomists ; some considering it as
forming three strata or fibres, and others but two. If the
stomach and a portion of the oesophagus attached to it be
moderately distended with air, and the external coat carefully
dissected away, many longitudinal fibres will appear on
every part of it, that evidently proceed from the oesophagus :
these fibres are particularly numerous and strong on the lesser
curvature of the stomach. — Beside the longitudinal fibres,
there are many that have a circular direction, and these are
particularly numerous towards the small extremity ; but it has
been doubted whether there are any fibres in the muscular
coat of the stomach that go directly round it. The whole sur-
face of the stomach, when the peritoneal coat is removed,
appears at first view to be uniformly covered by muscular
fibres ; but upon close examination, there are interstices per-
ceived, which are occupied with firm cellular membrane.

— The longitudinal or superficial muscular fibres of the stom-
ach, many of which can be traced from the oesophagus over the
cardiac orifice of the stomach, are grouped together so as to form
a thicker and stronger layer along the lesser curvature of the
stomach ; many of these fibres, if traced with care, will be found
continuous with the longitudinal fibres of the duodenum, while
others are terminated by insertion in the cellular coat of the
stomach near the pylorus. The circular fibres constitute the
sphincter muscle of the pylorus, by being thickened into a
muscular band at the line of separation between the stomach
and duodenum. There is another order of fibres called the

36 CELLULAR OR NERVOUS COAT OF THE STOMACH.

oblique, which are few in number, and spread over the left extre-
raity or greater tuberosity. But it seems an unnecessary degree
of refinement, to consider these fibres other than the circular
altered in their direction, by the expansion which the left end of
the stomach undergoes shortly after birth. They cannot
well be studied except in cases where the muscular coat of the
stomach is in a slate of hypertrophy.

— The use of these oblique fibres, appears to be, to compress
the great tuberosity of the stomach, and force the matters which
it contains into the body of the stomach and towards the
pylorus. The muscular fibres of the stomach are pale, and
present in regard to color, the appearance of ligamentous
fibres, for which they were mistaken by Helvetius and
Winslow. This appearance is common likewise, to the mus-
cular fibres of the intestinal canal, and of the bladder.
— In the young infant, the shape of the stomach is more tubular,
and like that of an intestine ; its left or splenic pouch not having
yet been formed. Hence vomiting occurs so much more readily
in the child than in the adult, the axis of the stomach in the
latter, corresponding at its two extremities more nearly with
that of the cardiac and pyloric orifices.

— The cardiac orifice of the stomach is not provided with any
sphincter, as it was thought to be by the ancients. —

In contact with the internal surface of the muscular coat is
the cellular stratum, which has been called the Nervous Coat
of the stomach. It is dense and firm, of a whitish color,
resembling condensed cellular membrane. It was considered
as different from ordinary cellular membrane : but if air be
insinuated into its texture, by blowing between the muscular
and villous coats while it yet connects them to each other, it ex-
hibits the proper appearance of cellular substance. It, however,
adds greatly to the general strength of the stomach, and the
vessels which terminate in the villous coat ramify in it.

— The cellular coat is the most resisting of all the tunics of
the stomach, and may be considered as the basis or frame-
work of its structure. It is more closely united to the muscular
coat on its outer face, than to the mucous on its inner. Its

INTERNAL OR MUCOUS COAT. 37

attachment to the latter, will be seen on close inspection, to be
by means of a substratum of delicate cellular tissue. —

The internal coat of the stomach in the dead subject is com-
monly of a whitish color, with a tinge of red. It is named
villous, from its supposed resemblance to the surface of velvet.
It has also been called fungous, because the processes analo-
gous to the villi are extremely short, and its surface has a
granulated appearance; differing in these respects from the
internal surface of the intestines. It is continued from the
lining membrane of the oesophagus, but is very different in its
structure. Many very small vessels seem to enter into its
texture, which are derived from branches that ramify in the
nervous coat. It is supposed by several anatomists of the
highest authority, to have a cuticle or epithelium ; and it is said
that such a membrane has been separated by disease. It ought,
however, to be remembered, that the structure of the villous
coat of the stomach and intestines, is essentially different from
the structure of the cuticle.

The internal coat of the stomach is generally found covered,
or spread over with mucus, which can be readily scraped off.
This mucus is certainly effused upon it by secreting organs, and
it has been supposed that there were small glandular bodies
exterior to the villous coat, which furnished this secretion ; but
the existence of such bodies is very doubtful, as many skillful
anatomists hvae not met with any appearance that could be
taken for glands, except in a very few instances, which would
not be the case if those appearances had been natural. Pores,
perhaps the orifices of mucous follicles, and also of exhalent
vessels, are very numerous, but no proper glandular masses
are attached to them. Glands, as has been already said, are
found in the triangular spaces between the lamina of the
peritoneum at the great and small curvatures of the stomach,
but these evidently belong to the absorbent system.* Besides

* The mucous coat of the stomach is, in its healthy state, thinner, softer, and
more vascular in the cardiac half of the stomach, than in the pyloric. The
villi or papilli as they are more properly called are better developed in the
pyloric region. The place of glands in the stomach is supplied mainly by
muciparous follicles, which are microscopical in regard to size. In pathological
VOL. II. 4

38 THE GASTRIC LK^UOR.

the mucus above mentioned, a large quantity of a different
liquor, the proper Gastric Juice, or fluid of the stomach, is
effused from its surface. It has been supposed that this fluid is
furnished by the small glandular bodies believed to exist
between the coats of this organ ; but, admitting the existence of
these glands, they are not sufficiently numerous to produce so
much of it as is found, and it is therefore probable that this
fluid is discharged from the orifices of exhalent vessels in the
internal surface.

Much information respecting the gastric liquor has been
obtained within a few years past by the researches of physio-
logists, and they are generally agreed that it is the principal
agent in the effects produced by the stomach upon alimentary
substances.*

As the muscular coat of the stomach frequently varies its
dimensions, the villous and nervous coats, which have no such
power of contraction, cannot exactly fit it. They there-
fore generally appear larger, and of course are thrown into folds
or rugae. These folds are commonly in a longitudinal direction ;
but at the orifices of the stomach they are arranged in a radi-
ated manner, and sometimes they are observed in a transverse

conditions of the membrane, these follicles sometimes appear round, sometimes
ovular, globular or flattened, and are believed to be analogous in structure and
function, to the blennogenous apparatus of Breschet, which assists to form the
cuticle of the skin. A cuticle ;7ro;?er does not extend farther dov?n the alimen-
tary canal than the cardiac orifice of the stomach, at which place it terminates,
as Chaussier first observed, in a crescentic margin. A delicate epithelial facing
is however continued over the mucous membrane, throughout the whole length
of the tube. — f.

* On this subject, the student may consult with advantage —

M. Reamur. In the Meraoires of the Academy of Sciences for 1752.

John Hunter. London Philosophical Transactions for 1772; and also his
observations on the Animal Economy, 1786.

Dr. Edward Stevens. Inaugural Thesis de Alimentorum Concoctione, Edin-
burg, 1777.

The Abbe Spalanzani. Dissertations relative to Natural History, &c. The
first volume of the English translation contains the author's dissertations on
digestion, and also the first paper of DIr. Hunter, and the Thesis of Dr. Stevens,
as well as an account of the experiments of Mr. Gosse of Geneva.

In addition to these, there are several interesting essays in the French, Ger-
man, and Italian languages, a compilation of which is to be found in Johnson's
"History of the Progress and Present Slate of Animal Chemistry." See vol,
i. p. 158.

iiSwAii/H.'.x •/..

THE PYLORUS. 39

direction. They depend upon the contraction of the muscular
fibres, and disappear entirely when the stomach is laid open
and spread out.

At the lower orifice is a circular fold, which is permanent,
and constitutes the valve denominated Pylorus. It appears
like a circular septum with a large foramen in its centre, or
like a flat ring. The mucous and cellular coats of the stomach
contribute to this, merely by forming the circular fold or ruga ;
and within this fold is a ring of muscular fibres, evidently con-
nected with the circular fibres of the muscular coat of the sto-
mach, the diameter of which at this place is not larger than
that of an intestine : the fibres of this ring seem a part of the
muscular coat projecting into the cavity of the stomach and
duodenum. If a portion of the lesser extremity of the stomach
and the adjoining part of the duodenum be detached, and laid
open by a longitudinal incision, and then spread out upon a
board, the internal coat can be very easily dissected from the
muscular, and the pylorus will then appear like a ridge or
narrow bundle of muscular fibres, which run across the extend-
ed muscular membrane. It is evident that when the parts
are replaced so as to form a cylinder, this narrow fasciculus
will form a ring in it. Tlius arranged the circular fibres can
readily close the lower orifice of the stomach.

The pylorus separates the stomach from the duodenum ;
and this separation is marked exteriorly by a small circular
depression, which corresponds exactly with the situation of the
pylorus.

The arteries of the stomach are derived from the Cceliac — the
first branch which the aorta sends ofi" to the viscera of the
abdomen. This great artery, immediately after it leaves the
aorta, is divided into three branches, which are distributed to
the stomach, the liver, and the spleen, and are called the Supe-
rior Coronary or Gastric, the Hepatic and the Splenic.
Besides the first mentioned branch, which is distributed princi-
pally to the neighborhood of the cardia and to the lesser
curvature, the stomach receives a considerable branch from the
hepatic, which passes along the right portion of its great curva-

40 LYMPHATICS AND NERVKS OF THE STOMACH.

ture, and has been called the right gastro-epiploic, and another
from the spleen, which passes along the left portion of the
great curvature, and has been called the left gastro-epiploic.
In addition to these branches, the splenic artery, before it
enters the spleen, sends off several small arteries to the great
extremity of the stomach, which are called vasa brevia.

These vasa brevia generally arise from the main trunk of
the splenic artery, but sometimes from its branches.

The veins which receive the blood from these arteries have
similar names, and pursue corresponding courses backwards :
but they terminate in the vena portarum.

The absorbent vessels of the stomach are very numerous
and large: they pass to the glands which are on the two curva-
tures, and from thence to the thoracic duct. It is an important
fact relative to the history of digestion, that there are good
reasons for doubting whether chyle commonly passes through
them, notwithstanding their number and size.*

The nerves of the stomach are derived from the two great
branches of the par vagum nerves which accompany the oesopha-
gus and are mostly spent upon this organ, and from branches
of several plexuses, which are formed from the splanchnic por-
tions of the intercostal nerves.

— The par vagum nerves form a plexus round the cardiac
orifice, and are distributed, the left on the anterior, and the
right on the posterior face of the stomach.

— These nerves can be traced into the muscular coat of the
stomach, and some of them as far as the duodenum.
— The section of these nerves, paralizes the muscular coat of
the stomach. They serve to connect the stomach, function-
ally, with the oesophagus, the pharynx, larynx, lungs and
heart. The nerves which the stomach receives from the plex-
uses of the abdomen, in like manner connect it with the
abdominal viscera. —

* Sabatier, however, in one subject observed white lines on the stomach,
which he suspected to be lacteals. See his account of the absorbents of the
stomach.

THE INTESTINES. 41

Of the Intestines.

The intestines form a continued canal from the pylorus to
the anus, which is generally six times the length of the subject
to which they belong.* Although the different parts of this
tube appear somewhat different from each other, they agree in
their general structure. The coats or lamina of which they are
composed, are much like those of the stomach, but the perito-
neum which forms their external coat does not approach them
in the same manner; nor is it continued in the form of omentum
from the whole tube, their being only a certain portion of intes-
tine, viz. the colon, from which such a process of peritoneum is
continued.

The Muscular Coat, like that of the stomach, consists of
two strata, the exterior of which is composed of longitudinal
fibres, which adhere to the external coat, and do not appear
very strong. The other stratum, consisting of circular or
transverse fibres, is stronger, as the fibres are more numerous.
It is observable that they adhere to the longitudinal fibres ; and
they seldom, if ever, form complete circles.

The cellular substance immediately within the muscular
fibres resembles the nervous coat of the stomach in its firmness
and density. It is likewise so arranged as to form many
circular ridges on its internal surface, which support to a certain
degree the permanent circular plaits of the internal coat, called
valvulae conniventes.

The inner surface of the internal coat has been commonly
compared to that of velvet, and the coat is therefore called
villous ; but there is certainly a considerable difference

* This is a rule a long time admitted among anatomists, making the small
intestines twenty-four or twenty-eight feet in length, and the large intestines
about six more. Cruvielhier considers the small intestine on the average
about 20 feet in length, and the large, four to five feet. — But this mode of mea-
surement is found to be totally defective when applied to comparative anatomy,
and Dr. Horner has found it applicable only to man, when the intestine is left
attached to the mesentery ; for, as he observes, "if it be cut off and straight-
ened, the small intestine will measure thirty-four feet, which, added to the eight
feet which the large intestine measures when treated in the same way, will
amount in all to forty-two feet. If to this estimate of the length is added what
is lost by the doubling of the mucous coat, the entire length of surface must
amount to nearly sixty feet, at least in many subjects." — p.

4*

42 LIEBERKUHN ON THE VILLOUS COAT.

between these surfaces ; for if a portion of the small intestine
be inverted, and then suspended in perfectly transparent water,
in a clear glass, and examined with a strong light, it will
appear like the external surface of the skin of a peach, on
which the down or hair-like processes are not so close as those
on velvet. On this surface, between the villi, there are many
orifices of mucous follicles and of exhaling vessels.* Exterior
to the villous coat, many very small glandular bodies are some-
times found, which are called after their describers Glandulae
Brunneri and Peyeri.

The internal coat of the upper portion of the intestinal tube
is arranged so as to form a great number of transverse or circu-
lar folds or plaits, called Vahul<B Conniventes, which do not
generally extend round the intestine, but are segments of
circles ; they are so near each other, that their internal edges,
which are very movable, may be laid upon the folds next to
them, like tiles or shingles. It is evident that this arrangement
of the internal coat must add greatly to its length. This coat
is extremely vascular, so that in the dead subject it can be
uniformly colored by a successful injection. The minute
structure of it has been the subject of very diligent inquiry.
There can be no doubt but that an immense number of exhaling
and of absorbent vessels open upon it ; but there are many dif-
ferent opinions respecting the termination of one set of vessels
and the commencement of the other.

A very interesting account of the Villous Coat was published
in 1744, by Lieberkuhn, who was considered by his contem-
poraries as a most expert practical anatomist, and was also very
skilful in microscopical examinations, for which he was particu-
larly calculated, as his natural powers of vision were uncom-
monly strong. In his essay he refers to his preparations, which
were at Berlin, and which appear to have excited great surprise

♦ It appears clearly, from the account of Lieberkuhn, that the orifices or
terminations of the arteries on the intestines, are distinct from the follicles ;
for he forced injections from the arteries into the cavity of the intestines, and
found the follicles still filled with mucus. He then urged the injection further,
and filled the follicles, or forced the mucus out of them.

HEWSON AND OTHERS ON THE VILLI. 43

in the minds of the members of the Academy of Sciences of
Prussia, at a time when one of the first anatomists of Europe,
the celebrated Meckel, was of their number.

According to this account the internal surface of the small
intestines abounds with villi, and with the orifices of follicles.
These villi, are about the fifth part of a line in breadth. In each
of them is a cavity filled with a soft spongy substance, which
has one or more orifices communicating with the intestines, and
from which also proceeds a lacteal vessel. On the membrane
which forms this cavity, blood-vessels are most minutely rami-
fied. This cavity he calls an ampullula, and supposes it to
constitute the principal part of the villus. By injecting the
arteries of the intestine, he was able to pass a fluid through the
ampullula into the cavity of the gut ; he kept a stream of air in
this way passing through the ampullula until it was nearly dry
and stiff, and then laid it open with a fine instrument. From the
appearances which then presented, he inferred that the cavity of
the ampullula was occupied with a spongy or cellular substance.
Around each villus he found a number of mucous follicles,
which often were filled with a tenacious mucus : and distinct
from these must be the exhalent orifices, which discharged a
fluid injected by the arteries without passing through the
mucous follicles.

Lieberkuhn died early, and left but one essay on this subject,
which was originally published in Holland, in 1744, but has
been republished by the Academy of Berlin, in their Memoirs ;
and also by Mr. John Sheldon, of London.

This account of Lieberkuhn appears to have been admitted
by Haller : but it has been rigidly scrutinized by some of the
anatomists of London, who were particularly interested with
the subject, as they had paid great attention to the absorbent
system, and were very successful in the investigation of it.

The late Mr. Hewson, whose opinion is entitled to the
greatest respect, rejected the idea of the ampullula, and believed
that the villi are composed of net-works of lacteals, as well as
arteries and veins ; although he added that " this is the only

44 FYFE AND OTHERS ON THE VILLI.

circumstance concerning these parts in which he should differ
from this very acute observer."*

!Mr. Sheldon agrees with Lieberkuhn : but Mr. Cruikshank
asserts, that, "in some hundred vilh, he has seen the lacteals
originate by radiated branches, whose orifices were distinct on
the surface of the villus. The villus being transparent, when
the intestine was immersed in water, these branches, filled
with chyle, could be seen passing into the lacteal. Mr. Cruik-
shank therefore supposes that Lieberkuhn was mistaken, and
that the spongy cavity, or ampullula, was the common cellular
membrane, connecting together all the arteries, veins, nerves,
and lacteals.

It seems probable, from Mr. Cruikshank's statement, that
Dr. William Hunter held the same opinion with himself. And
there is also reason to believe that Monro the second, who
studied anatomy at Berlin, held a different opinion from Lie-
berkuhn.

Mr. Fyfe, who has been much employed in the investigation
of the absorbent system, and must be perfectly acquainted with
the preparations of Monro, asserts that each lacteal takes
its rise upon one of the villi by numerous short radiated
branches, and each branch is furnished with an orifice for im-
bibing chyle.

Several of the late French writers adopted the opinion of
Lieberkuhn ; but his countryman Soemmering gives a different
account of the subject. He says, that, besides the blood-
vessels, each villus consists of a fine net-work of absorbent
vessels, whose orifices may be distinctly recognized ; and that
from six to ten of these orifices are sometimes discovered.

Mascagni, who has published the most extensive work upon
the absorbent system that has yet appeared, supposes Lieber-
kuhn to have been mistaken, and confirms the description of
Hewson : but he also agrees with Hewson in his opinion of the
general accuracy of Lieberkuhn.

Notwithstanding their differences respecting the origin of

* See Hewson's Experimental Inquiries, vol. 2, page 171.

DIVISION OF THE INTESTINES. 45

the lacteals, all these observers have agreed, that the orifices
which communicate with the lacteals are on the villi ; and
that these villi contain also very fine ramifications of blood-
vessels. They have also agreed that the surface of the intes-
tines in the intervals of the villi seems occupied with the
orifices of ducts or of exhalent vessels.*

Division of the Intestines.

Although there is a considerable degree of uniformity in the
structure of the intestinal canal, different parts of it are very
distinguishable from each other by their exterior appearance,
by their size, their investments, and their position.

The first division is into two great portions, which are very
different from each other in their diameter and length, as well
as their situation ; the first portion being much smaller in diam-
eter, and near four times the length of the other.

These portions are therefore known by the names of Great
and Small Intestines, and the line of separation between them
is very strongly marked ; for they do not gradually change
into each other, but the alteration in size and in exterior
appearance is very abrupt, and their communication is not
perfectly direct. A considerable portion of the Great Intestine
is fixed immovably in the abdomen, while a large part of the
Small Intestine is very movable.

Each of these great portions of the intestinal tube is subdi-
vided into three parts. Thus, in the Small Intestine, there is
a piece at the commencement called Duodenum, a great part
of which has no coat from the peritoneum, and is immovably
fixed in one situation ; while all the remainder of the small
intestine has a uniform covering from the peritoneum, and is

* On this subject the student will consult with adv^antage, Hewson's Experi-
mental Inquiries, vol. 2 ; Sheldon's History of the Absorbent System, part 1st ;
Cruikshank on the Anatomy of the Absorbent Vessels ; and the Historia Vaso-
rum Lymphaticorum Corporis Humani, of Mascagni.

— The more recent investigations of Beclard, Meckel, Breschet, Muller, Dr.
Horner and others have a tendency to disprove the existence of absorbing
orifices on the surface of the villi ; vide, Absorbent System. — p.

46 THE SMALL INTESTINES.

very movable. This last piece, notwithstanding its exterior
uniformity, is considered as forming two parts. The upper-
niost two-fifths form one part, which is called Jejunum ; and
the remainder is called Ileum. The Great Intestine com-
mences in the lower part of the right side of the abdomen, and
after proceeding up that side, crosses over to the left, along
which it descends to the lower part again, when by a peculiar
flexure it proceeds to the centre of the posterior margin of the
pelvis, from which it passes down to the anus. A short portion
of this intestine, which is below its junction with the ileum, is
called CcBCiim ; the part which proceeds from this, round the
abdomen, is called Colon ; and the portion which is in the
pelvis is called Rectum.

Of the Small Intestines.

Previous to the description of the small intestines, it is neces-
sary to observe, that the Mesocolon, or process of the peritoneum
connected to the transverse portion of the colon, forms a kind of
movable and incomplete septum, which divides the abdomen
into an upper and lower apartment. Above this septum are
the stomach, the commencement of the duodenum, the liver,
and the spleen ; below it, that portion of the small intes-
tine which is called jejunum and ileum, makes its appearance
The portion of the intestine which passes from the stomach to
the jejunum, and is called Duodenum, is so much involved by
the mesocolon, that the greatest part of it cannot be seen without
dissecting the mesocolon from its connection with the back of
the abdomen. — For the duodenum proceeds backwards from
the pylorus, and passing down behind the peritoneum, enters
a vacant space between the two lamina of the mesocolon ; it
proceeds for some distance in this space, and then emerges on
the lower side of the mesocolon. Here the duodenum termi-
nates, and the small intestine then is invested by the peritoneum
in such a manner as to form the mesentery, which continues
with it throuo-hout its whole course to the great intestine. This
portion of the intestine although very uniform in its exterior
appearance, as has been observed before, is divided into Jeju-

THE DUODENUM. 47

num and Ileum : tlie jejunum being the upper portion, which
begins at the mesocolon ; and the ileum the lower portion, which
opens into the great intestine.

Of the Duodenum.

The length of this intestine is equal to the breadth of twelve
fingers, and hence its name. It is very different from the rest
of the small intestine, not only as respects its position and
investment by the peritoneum, but on account of its connexion
with the liver and pancreas, by means of their excretory ducts
which open into it. From this connexion with these glands,
probably, all the peculiarities of its position are to be deduced.

When the stomach is in its natural situation, the pylorus is at
some distance from the back of the abdomen. The duodenum
proceeds backwards from this point, and passes near the neck
of the gall bladder, being here connected with the small oment-
um ; it then curves downwards, and descends before the right
kidney, sometimes as low as the lower part of it ; then it curves
again and passes over to the left : after it has arrived at the left
side of the spine, at the second or third lumbar vertebra, it
projects forwards and downwards to form the jejunum. The
only portion of this intestine which is movable, is that which
is in sight as it proceeds immediately from the pylorus, being
about an inch and a half, or two inches in length. The remain-
der is connected to the back of the abdomen, and lies between
the two lamina of the mesocolon. In its progress it passes
before the aorta and the vena cava, but the principal branch of
the vena portarum is before it.

The duodenum is larger in diameter than any other part of
the small intestines, and has a stronger muscular coat. Its
general situation admits of great dilatation, and it has been
called a second stomach, (ventriculus succenturiatus.) Its
internal coat is strictly villous in the anatomical sense of the
word; and its folds, the valvulae conniventes, begin at a small
distance from the pylorus. The orifices of many mucous ducts
are to be seen on its surface. It is supposed that some of these
are the terminations of ducts from ths glands of Brunner, which

48 THE JEJUNUM AND ILEUM.

sometimes appear in the villous coat, or very close to it exte-
riorly ; being small flat bodies, with a depression in the centre,
and a foramen in the depression. They are sometimes very
numerous at the upper extremity of this intestine, and diminish
gradually towards the other extremity.

, The biliary and pancreatic ducts open posteriorly into the
duodenum, rather above the middle of it. The orifice of these
ducts is generally surrounded by a small tubercle, which is
oblong, somewhat rounded at one extremity, and pointed at
the other. Sometimes this orifice is in a plait, like one of the
valvulse conniventes. Most commonly the two ducts unite
before they perforate the coat, so as to form but one orifice ;
and sometimes they open separately, but always very near to
each other.

Absorbent vessels, which contain chyle, are found on the
duodenum.

The Jejunum and Ileum

Are situated in the abdomen very differently from the duode-
num. When the cavity is opened and the omentum raised,
they are in full view ; and every portion of them except the
two extremities and the parts near them, can readily be moved.
This freedom of motion is owing to the manner in which they
are invested by the peritoneum ; or, in the technical language
of anatomy, to the length of their mesentery. They agree in
their structure with the general description of the small intes-
tines, but their muscular coat is rather weaker than that of the
duodenum. The valvulae conniventes are very numerous and
large in the upper part of the tube, or jejunum ; and gradually
diminish in number, until they finally disappear in the lower
part of the ileum. The villous coat is in perfection in the
jejunum, the villi being more conspicuous there than in any
other part of the intestinal tube. There are frequently found,
exterior to this coat, but intimately connected with it, many
small glandular bodies of a roundish form, which are often
clustered together at that part of the intestine which corresponds
with the interstice of the lamina of the mesentery. They are

THE JEJUNUM AND ILEUM.

49

called Peyer's glands, after the anatomist who first described
them ; and are supposed, like the glands of Brunner, to secrete
mucus. If a portion of the jejunum be inverted, and mode-
Fig-. 136.*

* 1. The stomach. 2. The oesophagus opening into the stomach, and form-
ing the cardiac orifice. 3. The great cul de sac, or splenic extremity of the
stomach. 4. The pyloric orifice of the stomach. 5. The commencement of
the duodenum. 6. The elbow formed by the duodenum to receive the head of
the pancreas. The transverse course of the duodenum across the spine to the
left side is not seen to its proper extent in the drawing, the jejunal end of the
duodenum being depressed in order to bring the small intestines belter into

VOL. II. 5

50 THE JEJUNUM AND ILEUM,

rately distended with air, these bodies appear very distinctly in
it, dispersed at small distances from each other. In the ileum
they appear in small clusters, which often have the appearance
of disease.

No natural line of separation for distinguishing the jejunum
and ileum from each other, is to be found ; but these names are
still retained ; and, therefore, the rule laid down by Winslow is
generally adopted, viz. to name the first two-fifths of the tube
jejunum, and the remainder ileum. There are, however, some
important differences between these portions of the intestine.

In the jejunum, the valvulae conniventes are so numerous, that
they lie in contact with each other, as shingles on the roof of a
house ; in the ileum they gradually diminish in number, and
finally disappear. In the jejunum, the villi are much stronger
than they are in the ileum.

It is very difficult to acquire a precise idea of the arrangement
of this part of the intestinal tube, while it is in the abdomen,
especially if it be much distended ; but if it be separated at each
extremity from the intestine with which it is connected, and
the mesentery cut off from the back of the abdomen, and the
whole then spread out upon a flat surface, it will appear, as
has been already said, that the intestine is arranged so as to
form a semicircle, or large curve ; the concavity of which is
opposite to the back of the abdomen, while the convexity
presents forward. It will also appear, when thus placed upon
a table, that the intestine, while connected with the mesentery,
is laid into many folds. It has been supposed, that the middle
portion of the mesentery, and the intestine connected with it,
is generally in the umbilical region ; and the two portions on
the sides of it are in the iliac regions ; but their situation in the
abdomen varies considerably at different times. When the
viscera of the pelvis are empty, a large portion of the small

view. 7. The jejunum. 8. The ileum, opening into the colon. 9. The caput
coli, or intestinum ccecum. 10. The appendicula vermiformis. 11. Ascending
colon. The number is placed on one of the three longitudinal bands of mus-
cular fibres. 12. Transverse colon. 13. Descending colon. 14. Sigmoid
flexure of the colon. 15. The rectum, terminated below by a strong band of
its circular muscular fibres forming the internal sphincter to the anus. The
dilatation or pouch of the rectum is seen above it.

THE MESENTERY. 51

intestine is in the pelvis ; but when those viscera are filled, the
intestine is in the general cavity of the abdomen.

The Mesentery

Is a process of the peritoneum, which is formed in the manner
of a plait or fold, and of course consists of two lamina. These
lamina proceed from the back part of the abdomen, and are
so near to each other, that they compose one substantial
process ; having cellular and adipose substance, blood-vessels
and nerves, with absorbent or lacteal vessels and their glands
between them.

The form of this process, when it is separated from the back,
and the intestines are detached from it, is somewhat semicircu-
lar ; that portion of its margin or edge which corresponds to
the diameter of the semicircle, is connected to the back of the
abdomen, and called the root of the mesentery ; the edge,
which is the circumference of the semicircle, is connected with
the intestine. The edge connected with the back of the abdo-
men is commonly about five or six inches in length : the semi-
circular edge, instead of extendino- fifteen or eighteen inches,
the ordinary proportion, is attached to a portion of intestine
sometimes twenty-four feet in length. The mesentery, on
account of this great difference between its diameter and cir-
cumference, has been compared to the ruffle of a shirt sleeve;
its roots being taken for the plaited edge of the ruffle, and the
circumference for its loose edge. But the comparison is not
precisely accurate ; for the mesentery is not plaited at its root,
but perfectly smooth, and free from every kind of fold. It
begins to enlarge towards its circumference, and enlarges to
that degree that it falls into plaits or folds : precisely such as
would exist in a semicircular piece of membrane about six
inches in diameter, if a number of simple incisions, of about an
inch and a half in length, were made in a radiated direction
from the circumference, and if portions like a sextant or quad-
rant were taken from a circular membrane three inches in
diameter, and united by their edges to these incisions, so that
their circumference might be continuous with the circumference

52 THE MESENTERjr.

of the large semicircular piece. In this case, the portions
like quadrants or sextants would assume a folded position like
the edge of the mesentery, while the middle of the semicircular
piece would preserve its regular form without folds ; as is the
case with the mesentery at some distance within its circumfer-
ence. By many additions of this kind, the circumference of a
membrane, which was originally a semicircle of five or six
inches, may be extended so as to exceed greatly that of tiie
mesentery. It seems of course impossible to form an accurate
model of the mesentery with a single piece of membrane or
paper; but it may be easily made with clay, or any ductile
substance. A model of this kind must necessarily be folded
after the manner of the mesentery ; and its circumference, like
the mesentery, would appear as if formed of portions of the
circumference of smaller circles united to each other.*

The root of the mesentery commences with the jejunum on
the lower side of the mesocolon, at the left of the spine, and
extends downwards near to the right iliac region, crossing the
spine obliquely. When it is examined in its natural situation,
the peritoneum is found continued from the back of the abdo-
men to the intestine ; it then surrounds the intestine, and con-
tinues from it to the back of the abdomen again. There must
therefore be two lamina of peritoneum in the mesentery, and
there must be a small portion of intestine answering to the
interstice between these lamina which is not covered by the
peritoneum. The blood-vessels, and absorbents, or lacteals
pass most commodiously to the intestines between these lamina ;
for they are connected with large trunks that lie on or near the
spine, and the root of the mesentery commences there.

The glands connected with the lacteals or absorbents are
very conspicuous in the mesentery, and are commonly called
mesenteric glands. They are of different sizes, from more than
half an inch to one or two lines in diameter. They are very
numerous, and scattered irregularly, but are seldom observed

* A model, upon the plan first mentioned, was invented by Dr. J. G. Shippen.
It has been proposed, I believe by M. Gavard, to make one with a single piece
of buckskin, of a semitircular form, by stretching it at the circumference.

LARGE INTESTINES. od

very near to the intestine. They are often enlarged in conse-
quence of disease, especially in children.

The nerves of the small intestines which are derived princi-
pally from the superior mesenteric plexus, are also to be found
here.

The adipose matter between the lamina of the mesentery is
very often in large quantity, but varies, in proportion to the
general quantity of adeps in the subject.

OF THE GREAT INTESTINES.

The Cacum and Colon

Are very different from the small intestines in many respects.
They are much larger in diameter ; their external surface is
marked by three longitudinal bands of light color, which
extend the greatest part of their length, and are placed nearly
at equal distances from each other ; the spaces between these
bands are marked by transverse indentations, which pass from
one band to the other, at short but unequal distances. At
these indentations the coats of the intestine are pressed inwards,
as if a fine thread had been drawn round it externally, while
the spaces between them are full and tumid, and on this account
are called cells.

The great intestine, with these appearances, begins, as has
been already observed, in the right iliac region, by a rounded
end which rests on the fossa or concave surface formed by the
costa of the ileum; from this it is continued upwards in the
right lumbar region, anterior to the kidney, called ascending
colon, until it arrives near the liver, when it forms a transverse
part or curve, called the arch of the colon, and passes directly
across the abdomen to the left side. In this course it approaches
so near to the under side of the liver, that it is often in contact
with it, and with the gall-bladder, which, after death, tinges it
with a yellow color. On the left side it passes down the lumbar
region , forming the descending colon, before the kidney, to the
left iliac region ; here it is curved so as to resemble the
Roman letter S, inverted, forming the sigmoid flexure ; this

5*

54 THE C^CUM.

curve generally carries It to the right side of the spine, and
then brings it back to the centre of the sacrum. Here the in-
testine changes its course, and passing into the pelvis, continues
downward, in contact with the sacrum and coccyx, and
partaking of the curvature of those bones, until it terminates at
the anus, where it is connected with the sphincter and levator
ani muscles.

About two inches from the commencement of the great in-
testine, the ileum opens into it laterally ; and all that portion
which is between its commencement and the insertion of the
ileum is termed Ccccum, or the blind intestine : that part of the
great tube, which is included in its circuitous course from the
insertion of the ileum to the posterior part of the brim of the
pelvis, is called Colon; and the remainder, or the part which is
contained in the pelvis, is termed Rectum.

The Caecum is nearly as wide as it Is long ; it is fixed in the
right iliac fossa by the peritoneum, which invests it so that the
great body of the intestine projects from the surface of the fossa
covered by the peritoneum ; but a portion is in close contact
with the surface, and connected to it by the cellular membrane.
Its external surface covered by the peritoneum, is marked by
two of the bands or stripes before mentioned, which proceed on
it lengthways. These bands are in full view, but the third
band is generally on that part of the intestine which rests on
the iliac fossa, and is therefore out of sight. At the rounded
extremity of the caecum, situated anteriorly and internally, is
a small process resembling an earth-worm in form and size :
this is therefore called, Appendicula Vermiforis. It is hollow,
and communicates with the cavity of the caecum, but has its
other extremity closed up. It is composed of the same number
of coats and has the same structure as the great intestine : its
length varies from two to four inches.

— After the stomach, the caecum may be considered the
largest portion of the intestinal canal.

— In the foetus its diameter appears to be nearly the same as
that of the adjoining part of the colon, and its subsequent
increase in diameter over that of the colon, appears to be

THE COLON. 55

mainly owing to the stagnation of the faecal matters, in conse-
quence of the dependent position of this part of the large
intestine, and the transverse direction by which the contents of
the ileum are discharged into it.

— The caecum varies much, however, in different persons, in
regard to its length as well as its diameter.

— Retentions of the faecal matter often take place in it, in cases
of constipation, which have frequently led to inflammation of
this bowel, and to swelling and abscess of the cellular tissue
behind it in the iliac fossa or lumbar region. —

The longitudinal bands above mentioned commence at the
junction of the appendix with the caecum, and continue through-
out the extent of the colon. They appear to be formed by
some of the longitudinal fibres of the muscular coat, which are
arranged close to each other. These fibres seem to be shorter
than the coats of the intestine, and the interior coats adhere
firmly to them. Thus are produced the indentations and cells;
for if the bands are divided transversely, the indentations dis-
appear, and the surface of the intestine becomes uniform. One
of these bands is covered by the mesocolon.*

The circular or transverse fibres of the muscular coat of the
cacum and colon are very delicate, and not numerous.

The internal coat differs materially from that of the small
intestines, although at first view they seem to resemble each
other ; for if a portion of the ileum and of the colon be inverted
and suspended in water, no villi can be seen with the naked
eye on the internal coat of the colon, while those of the ileum
are very visible. The glands exterior to this coat are larger
than those on the small intestines.

Instead of valvulae conniventes, are the ridges made by the
indentations or depressions above described, which separate
the incomplete cells from each other. These ridges differ
essentially from the valvulae conniventes, because all the coats
of the intestine are concerned in their formation, whereas the

* In the fetus, no cells are visible in the colon. Their development appears
to be owing to the growth of the longitudinal fibres not taking place so rapidly
in regard to length, as that of the other coats ; which necessarily causes the
crimping of the latter into folds, and the formation of cells. — p.

56

THE COLON.

valvulae conniventes are formed by the villous coat only : they
also project into the cavity of the intestine, while the valvulae
are laid on its surface. They pass only from one longitudinal
band to another, and, in consequence of this, the cells are small,
and the position of each band is very evident when the intes-
tine is laid open.

The communication of the ileum with the great intestine has
been already stated to be on the left side of it, about two inches
from its commencement. The aperture is so constructed, that
it is considered as a valve, and is called the valve of Bauhin,
or of Tulpius, after the anatomists who have described it.* The
appearance of the aperture is as follows : If the caecum, with a
small portion of the ileum and of the colon may be separated
from the other intestines, and kept in an inflated state until it
be so dry as to preserve its form when opened, and then if the
caecum and colon be laid open opposite to the aperture of the
ileum, a large transverse ridge, resembling some of the ridges
or folds just described, will be seen projecting into the cavity of
the intestine. In the internal edge of this fold is a long slit or
Fig. 137.f opening, which forms the communication
between the two intestines. It is obvious
that the form of this fold must be that of a
crescent ; and that its two surfaces with the
slit between them, must have the .appear-
ance of two lips, which would readily permit
a fluid or substance of soft consistence to
pass from the ileum into the great intestines,
but must impede, if not prevent, its passage
back ; especially if the large intestines were
distended, as then the lips would be pressed against each other.
When, the peritoneal coat is dissected from each of the intes-

* Posthius ia 1566 ; Vidus Vidius about 1569 ; Albert! in 1581 ; andVarolius,
who died 1575, each lay claims to the discovery of it. Bauhin's claims are in
1579— n.

t A view of the Ileo-coecal valve as it appears in the dried intestine, b, The
upper segment of the valve, orilio-colic as it might be called, which is horizon-
tal, a, The lower or ileo-ccecal forms an inclined plane of about 45°, and both
are parabolic, c, The closed end of the cascum, d, Ascending colon tied and
cut off near its middle, e. Ilium opening into the colon, through the valve.
/, Appendicula vermiformis.

POSITION OF THE RECTUM. 57

tines at their place of junction, and this structure is then
examined from withoxit, it appears as if a transverse or half
circular indentation had been formed by the villous coat of the
great intestine, and that the internal coat of the extremity of
the ileum was pressed into this indentation, and united to the
internal coat of the great intestine which formed it ; while there
was a slit both in the indentation and in the end of the ileum,
which formed a communication between the cavity of the great
intestine and the ileum. The longitudinal fibres of both intes-
tines, as well as their external coats, seemed to be united, so as
to form a common cover for them ; while the circular fibres
were blended in the two portions of the indentation which form
the lips of the orifice.

This orifice is, of course, transverse with respect to the
intestine. It has been observed, that there was a difference in
the thickness and strength of the two lips or valves ; that the
lower valve was the strongest and appeared to have the largest
proportion of muscular fibres in its composition. At the extre-
mities of the orifice, and near each end of the fold or ridge, are
tendinous fibres, and which give strength to the structure :
they are called the Retinacula of Morgagni, as they were first
described by that anatomist.

There is a great reason for believing that this valve cannot
prevent the retrograde motion of the contents of the intestines
in all cases ; for in some instances of hernia and of colic, matter
perfectly stercoraceous has been vomited, and the probable
inference from such a state of the ejected matter is, that this
matter has been in the large intestines. It is also said, that
suppositories and enemata have been discharged by vomiting.

On the right and left sides of the abdomen, the colon is in
close contact with the posterior surface of the cavity. The
peritoneum which covers this surface extends over the intestine
also, and thus retains it in its position. The great arch of the
colon, which is loose and moves far from the back of the abdo-
men, is invested by the two lamina of the omentum, which, after
surrounding it, unite again and form the mesocolon. Connected
with the exterior surface of the colon are many processes, com-

58 POSITION OF THE RECTUM.

posed of adipose membrane, varying in length from half an
inch to an inch and a half: these appear to be of the nature of
the omentum, and are therefore generally denominated Appen-
dices EpiploiccB.

The Rectum.

After forming the sigmoid flexure, the colon terminates ; and
the rectum begins opposite to the lower surface of the last
lumbar vertebra, and nearly in contact with it ; from this it
proceeds downwards, forming a curve like the sacrum, until it
terminates at the anus ; where it is invested with the muscles
called the sphincter and levator ani. It is called rectum,
because in this course it is supposed not to incline to either
side ; but it is often found on one side of the middle line.*

This intestine being in contact with the posterior surface of
the pelvis, is covered, on its anterior surface only, by the perito-
neum which lines the posterior surface of the pelvis ; and it is
fixed in this situation by the peritoneum, as the colon is on the
right and left sides of the abdomen, but more loosely ; and,
therefore, the term Mesorectum has sometimes been applied to
that portion of the peritoneum which is analogous to the
mesentery and mesocolon. The peritoneum does not extend
to the end of the rectum ; for it is reflected at the lower part of
the pelvis from the rectum to the bladder, or uterus, and does
not line the bottom of the pelvis : so that the lower part of this
intestine, as well as that of the other viscera of the pelvis, is
below the peritoneum, and not connected with it.

The muscular coat of the rectum is much thicker and
stronger than that of any other intestine. The strata of the lon-
gitudinal and circular fibres which compose it are very distinct
from each other. The longitudinal fibres are most numerous,
and terminate at the insertion of the fibres of the levator ani
muscle.

The lower circular fibres are intimately connected with the
sphincter ani.

* Morgagni and Haller supposed it to be commonly on the left of the middle
line, and Sabatier on the right.

STRUCTURE OF THE RECTUM. 59

— The circular muscular fibres at the end of the rectum, are
so thickened as to form a sort of annular muscle, which projects
into the cavity of the intestine, like the pyloric valve of the
stomach. It is attached to the proper sphincter muscle below,
by cellular tissue, and like it and the muscles of the pharynx at
the other extremity of the canal, is in a great measure under the
control of the will, being supplied in part with nerves from the
cerebro-spinal system. It aids the sphincter in retaining the
faeces in the pouch of the rectum.

— The three longitudinal muscular bands of the colon at the
lower edge of the sigmoid flexure, separate into fasciculi, which
are distributed as they descend round the circumference of the
intestine, and form a thick uninterrupted layer round the
rectum. The longitudinal fibres of the rectum have been
shown by Professor Horner, to terminate in delicate tendons,
which pass between these two sphincter muscles, internal and
external, and turn upwards and inwards to be inserted on the
inner face of the mucous membrane of the rectum. Opposite
the lower edge of the internal sphincter, the mucous membrane
is thrown into a number of plaits or folds, in which the same
anatomical observer has pointed out a number of irregular
valvular pouches which open upwards. These when diseased
become a source of intolerable itching and irritation, which
attracted the attention of Dr. Physick, who was in the habit of
relieving the suffering they produced by their excision.*

The internal coat is very vascular, but the villous structure
is not apparent. Mucous follicles are also very numerous ; and
there are likewise some distinct glandular bodies exterior to this
coat, which vary in size in different subjects.

— The mucous membrane of all the large intestines, when
examined with the microscope under water, presents scarcely any
appearance of villi, but exhibits every where slight honey-comb-
like depressions, somewhat analogous to those of the stomach.
It is strewed with a multitude of follicles, (distributed tanqnam
Stella Jirmamente, according to Peyer,) depressed and perforated in

* For an excellent account of these parts, see article Anus, by Dr. R. Coates,
in the American Cyclopedia of Med. and Surg. Philadelphia. — p.

60 STRUCTURE OF THE RECTUM.

their centre, as seen in fig. 140, p. 71 ; and which in many sub-
jects especially old men, present at their orifices the appearance
of black spots. —

The quantity of mucus discharged from the rectum in certain
cases of disease, is sometimes very great. Tne internal coat, in
consequence of the contraction of the circular fibres exterior to
it, sometimes forms longitudinal folds, which have been called
its columns: these often disappear when the intestine is opened
lengthways and spread out. By the contraction of the longi-
tudinal fibres, the internal coat is often thrown into folds or
doublings, that must assume a transverse or circular direction ;
they occasionally pass down through the sphincter, and form the
prolapsus ani. The rectum is most plentifully supplied with
blood-vessels, to be described hereafter ; and it may be observed,
that, on the lower part of the internal coat, the veins are particu-
larly numerous.*

The internal coat of the rectum terminates abruptly just
within the anus, and is united to a production of the skin, which,
like the covering of the lips, is very delicate and vascular, and
has an epithelium, or very thin cuticle, spread over it. The
levator and sphincter ani muscles, with which the termination of
the rectum is invested, are described in the first volume.

The Absorbents of the Intestines, are commonly denominated
Lacteals.-f They originate on the internal surfaces of these
viscera, as has been already described. After passing through
the lymphatic glands, which are so numerous on the mesentery,
they generally unite and form one of the great trunks which
compose the thoracic duct. It is asserted, that some of the
absorbent vessels of the lower intestines unite to the lymphatics
of the loins.

The Nerves of the Intestines are principally derived from
the intercostals, or great sympathetics. From each of these

* No intestine in proportion to its size, receives so much blood as the rectum,
and the veins at its lower part not unfrequently exist in the form of a plexus.

t The Lacteals were first observed by Erasistratus and Herophilus, of the
school of Alexandria, during the reign of the Ptolemies ; and subsequently by
Aselli, of Pavia, in 1622, the knowledge of them having been lost for 19U0
years. — h

#

THE OMENTUM. 61

nerves, while they are in the thorax, an important branch,
called the ramus splanchnicus, arises. These splanchnic
branches pass through the diaphragm, and are the chief con-
tributers to the ganglions and plexuses formed in the abdomen.
A plexus derived from this source surrounds the superior
mesenteric artery, and another the inferior mesenteric ; and
from these proceed the nerves of the intestines.

The Omentum.

Requires a separate description, although several circum-
stances connected with its structure have been already noticed.
It often varies in its position ; but when it is rendered firm by
a quantity of adipose matter, it is spread over the intestines
like an apron, extending from the lower edge, or great curva-
ture of the stomach, towards the bottom of the abdomen.

As has been already said, it is an extension of the perito-
neum, in two lamina, from the concave surface of the liver to
the lesser curvature of the stomach ; and these lamina, after
surrounding the stomach, come in contact with each other near
its great curvature. From this portion of the stomach, from
the commencement of the duodenum, and also from the spleen,
the Omentum, composed of two lamina, descends over the
colon and the small intestines more or less low into the abdo-
men ; it is then folded backwards and upwards, and is continued
until it meets the great arch in the colon : here the lamina
again separate and enclose that portion of the intestine, on
the posterior side of which they again approach each other,
and form a membrane like the mesentery of two lamina,
which passes from the concave or posterior surface of the colon
to the back of the abdomen, where it is continued into the
membrane which lines that surface. This last portion is the
Mesocolon : the portion between the liver and stomach is called
the Omentum of Winsloiv, the lesser omentum or the omentum
hepatico-gastricum ; and the great portion between the stomach
and colon is called the Great Omentum, or the omentum gastro-
colicum. There is also a process of peritoneum continued from
that portion of the colon which is on the right side of the abdo-

VOL. II. 6

62 THE OMENTUM.

men, and from the coecum, which extends to some distance ; it
is formed of two lamina, that compose a cavity of an angular
form. This has been called the Omentum Colicum.

The great and small omentum, with a portion of the peri-
toneum on the back of the abdomen, form a sac, which encloses
a distinct cavity in the abdomen. The anterior part of this sac
is composed of two lamina, and between these lamina are the
stomach and the great arch of the colon. This cavity formed
by the two omenta, communicates with the general cavity of
the abdomen by a foramen of a semicircular form, called the
Foramen of Winslow, which is behind the great cord of the
vessels that go to the liver.

The omentum is so delicate in structure, that when free from
fat, it is very liable to laceration, merely by adhering to the
fingers, if they are dry. Winslow therefore advised that some
unctuous substance should be rubbed on the hands, before they
were applied to it.

The appearance of the great omentum is very different in
different persons. In the emaciated, it appears like a delicate
transparent membrane : in the corpulent, if is like a broad
mass of adeps, which sometimes is very thick. When it is thus
loaded with adeps, it is most commonly spread over the small
intestines : when it is free from fat, it is often compressed to-
gether, so as to form a small mass near the arch of the colon,
on the left side.

The principal blood-vessels of the omentum are derived from
those of the stomach, and are called gastro-epiploic arteries
and veins.

The use of this membrane in the animal economy has not
been ascertained with certainty. It seems probable that one of
its principal objects is to protect the small intestines, and lessen
the friction consequent upon their motion ; but it has been sup-
posed to answer several other important purposes.*

* See Halleri Elernenta Physiologiac, vol. vi. page 381 ; Gavard, Traite de
Splanchnologie, page 350 ; and Dr. James Rush's Inquiry into the use of the
Omentum.

GENERAL ANATOMY OF MUCOUS MEMBRANES. 63

General Anatomy of Mucous Membranes.

— The mucous membranes form the same sort of lining or
tegumentary covering to all the cavities of the body that the
skin does to the exterior ; and the two are continued insensibly
into one another at the orifices by which these cavities open
upon the surface. Hence the two are frequently spoken of as
the internal and external tegumentary systems. The first
general and satisfactory account of the mucous membranes we
owe to Bichat. He divided the whole class of mucous mem-
branes into two great divisions, the gastro-pulmonary , and
the genito-urinary. The gastro-pulmonary commences from
the mouth and nose, and from the eyes through the lachrymal
passages ; covers the nasal, buccal and pharyngeal cavities, and
is prolonged into the salivary ducts, the Eustachian tube, the
aerial passages and the whole length of the alimentary canal,
as well as the various secretory ducts which open into the
latter.

— The genito-urinary lines the urethra, bladder, ureters, (and
pelvis of the kidneys in both sexes,) as well as the vagina,
uterus, and Fallopian tubes of the female where it opens
through the peritoneum into the cavity of the abdomen. In
the male it is prolonged from the bladder into the ducts of the
prostate, the vesiculae seminales, and the vas deferens, to the
termination of the last in the seminiferous ducts of the testicle.
Beneath the mucous membrane is a layer of cellular tissue
formerly called the nervous coat from its whiteness, which is
never found to contain any adipose matter, and is rarely infiltrat-
ed with serum. This connects the membrane in general to a
muscular plane below, as in the alimentary canal ; sometimes to
a contractile fibrous tissue as in many of the excretory ducts;
and occasionally to the periosteum, as in the nasal cavities. It
serves, as a basis to the mucous membrane, a sort of chorion or
dermis analogous to that of the skin, but which is in general
much more delicate, soft and spongy in its character ; an appear-
ance which the skin itself presents in many of the inferior ani-
mals and in very young foetuses. It varies in its thickness in
different parts of the body. It will be found to diminish

64 GENERAL ANATOMY OF MUCOUS MEMBRANES.

successively in thickness as we examine it in the following
order; in the gums, the palate, nasal cavities, stomach, small
and large intestines, gall-bladder, urinary bladder, sinuses of
the head, and in the excretory ducts : in the last its tenuity
becomes extreme.

The squamous or tesselated epithelium or cuticle which as
was remarked vol. i. p. 438, is extended upon this membrane
from the skin covering the lips, terminates at the cardiac orifice
of the stomach ; that which passes in at the anus and vulva,
terminates upon the sphincter muscle and the lips of the
womb. In the stomach and intestines, the mucous mem-
branes are apparently covered with a coating or varnish
of mucous matter, which resembles the epithelium in its chemi-
cal composition, and seems to be even susceptible of being
converted into it, when dried and hardened by exposure to the
air, as has been observed in cases of artificial anus. But when
examined under a powerful microscope, the membrane is really
found covered with a pellicle or epithelium analogous to the
cuticle, which though not provided with vessels, is formed by a
deposit or secretion of nucleated cells from the chorion below.
These cells, lining hollow passages are constantly moistened
with fluids, are not steadily subjected to pressure, and develop
themselves in the form of oblong cylinders, arranged in a
single series like little columns perpendicularly to the surface
of the dermis of the membrane, to which their inner end is
attached. This pellicle or epithelium, is accordingly called the
cylinder epithelium. Each cylinder or nucleated cell contains
a central nucleus, and is broadest at the top. They are all
arranged as thickly as may be and in juxtaposition. The epi-
thelium here retains to the last its original cellular structure,
and is not flattened as upon the skin, &-c., so as to be converted
into scales, as in the squamous or tesselated epithelium. The
epithelial cells or cylinders are thrown off from time to time
and are mixed with the mucus, while their place is supplied
by new growths from the surface of the chorion. The cylinder
epithelia, as before observed, are met with elsewhere than in
the stomach and intestines, viz., in the nostrils, trachea, uterus
and gall-bladder.

GENERAL ANATOMY OF MUCOUS MEMBRANES. 65

■ — In some portions of the body, (as has already been observed,
vol. i. p. 438,) as in the nostrils, frontal and maxillary sinuses,
larynx, trachea, bronchia, vagina, uterus, fallopian tubes, &lc.
the cylinders are surmounted with particular filiform organs,
called cilia, which are endowed with an undulating rotary action,
apparently independent of nervous influence, and which accord-
ing to Henle continue to act a short time after death. They
are supposed to carry onwards the fluids which cover them.
They constitute what is called the ciliary epithelium.
— In some instances they have been seen attached to warty ex-
cresences belonging to the tesselated epithelium.
• — The mucous membranes vary in different parts in regard to
color from white to red, passing through all the intermediate
shades. They are red near their points of communication with
the skin, as in the pharynx and rectum ; of a pearl or pale
rose hue in the stomach ; and almost colorless in the centre
of the intestinal canal, except in cases where they have been
colored by disease or by the capillary injection which follows
asphyxia.

— The mucous membranes, are thrown in many places into a
number of loose folds, which amplify very considerably their
extent of surface. These folds may be seen in the nasal cavi-
ties, in the hollow organs in their undistended state as the sto-
mach and rectum where they are termed rugce, but particularly
in the small intestines, where they form an extensive series of
permanent doublings called the valvula conniventes, or valves of
Kerkringius.

— The surface of the membrane presents in many places, a
superficial honey-comb-like appearance, which is discernable
only after close investigation in the-stomach and gall-bladder in
^man, but is strikingly developed in the alimentary canal of our
domestic animals, and in many fishes.

— All that is known in regard to the chemical analysis of mucous
membranes, is, that they are insoluble in water, even by boiling,
but are easy of solution in acids, with which they form a pulp.
— These membranes, though possessed every where of many
characteristics common to the whole, vary somewhat in different
6*

66 THE VILLI.

parts of the body, especially in regard to their villi and their
follicles. —

Of the Villi, and Papillce.

' — On the free surface of the mucous membranes are found a
great number of papillary projections springing up from the
chorion or dermis of these membranes ; on the small intestines
they are so elongated and prominent, as to resemble the pile on
a piece of velvet, and have there been called villi. (See fig.
141, page 74.) Each villus, minute as it is, is formed of sepa-
rate parts arranged in a bundle consisting at least of one artery,
vein, nerve and absorbent, woven together by cellular tissue and
covered in by a thinly expanded fold of the mucuos membrane.
The papillae on the tongue, instead of a mucous layer are cover-
ed by the epidermis, (pcriglottis,) which is so thick in many
quadrupeds, as to constitute a hard corneous covering, and con-
vert the papillae into instruments of prehension. In the pharynx
and oesophagus the papillae hold a sort of middle station between
those of the tongue and those of the stomach.
— The papillae of the mucous membrane of the stomach, were
formerly described as villi ; and Gendrin proposed for distinction,
to call the gastro-intestinal the villous mucous membrane. But
this distinction will not hold. At early periods of fcEtal life, villi
are found on the mucous membrane of the stomach, but subse-
quently to birth, we discover only flattened papillary projections.
The villi properly speaking are now considered as papillae in a
modified form belonging only to the small intestines, where they
serve the purpose of facilitating the absorption of the chyle.
— If we examine by the aid of a strong glass, the mucous
membrane of the stomach under water exposed to the strong
light of the sun, we perceive the whole surface covered by
irregular and very superficial nipple-like projections and marked
by shallow grooves passing over the surface of the membrane,
so as to give it the appearance somewhat of the intestinal con-
volutions. These nipple-like projections are covered by fringed
or flattened papillae, and between them are seen the honey-

THE VILLI. 67

comb depressions which were described by Sir E. Home.*
When we examine an oblique or perpendicular cut of the mem-
brane under a simple microscope, we observe thousands of these
papillae projecting up from the surface of the membrane. The
honey-comb depression between these papillae according to the
observations of Dr. Boehm,f and Dr. Sprott Boyd,;]: are com-
posed of many tubular follicles, placed perpendicularly in the
membrane, and which open into the surface of the cell. The
diameter of these cells, according to Dr. Boyd, varied from
jioth to the gggth part of an inch. The bases of these follicles
rest upon the cellular coat of the stomach, and are considered
by Dr. Boehm, as similar to the tubular follicles of the large
intestines. (See fig. 140, page 71.)

— The villous or papillary prominences of the mucous mem-
branes are found in much greater number in the small intes-
tines than in any other part of the alimentary canal. They
were first discovered by Fallopius. They occupy the whole
length of the small intestines ; studding the valvulae conni-
ventes, as well as the spaces between them. Their number
is very considerable : Lieherkuhn estimated them at 500,000.
Some of the German anatomists, have more recently made

* Sir E. Home described these honey-comb depressions as existing only in
the left extremity of the stomach, and considered the remaining portion of the
stomach occupied by the villi. Careful inspection, as Cruveilhier has observed,
•will show, that the whole surface of the membrane is constructed alike in this
respect, with the exception, that the nipple-like or mammelonnated projections,
are more fully developed on the side of the pylorus, than at the cardiac extremity
of the stomach. A good idea of the appearance of the papillae of the stomach
when examined by the microscope, may be formed from an inspection of the
papillae villosse of the tongue, between the bases of which we are to consider
placed the honey-comb depressions.

Ruysh has divided the villous prominences of the gastric mucous membrane
into two classes, papilla and villi, in which he has been followed by some anato-
mists : hence the gastric mucous membrane has been called the villoso-papillary,
But this distinction does not appear to be well founded. Careful observation
■with the microscope, does not enable us to perceive any difference betwe€n
them, and they have heretofore been called indifferently, villi or papilla, and
considered as the representatives in the mucous membranes of the papillae of
the skin. — p.

t De Gland. Intes. Struct. Penit. Berol, 1835.— p.

X Essay on the structure of the mucous membrane of the stomach. Edin-
burgh, 1836.— p.

68 VESSELS AND NERVES OF MUCOUS MEMBRANES.

a higher estimate of their number than this. They assert
that there are 4000 to be seen upon every square inch of surface,
and which by their calculation would make a million of villi to
the small intestines.

— Those of the jejunum, according to the measurements of
Dr. Horner, are the thirtieth of an inch in length, and those of
the ileum the sixtieth. In the pyloric half of the stomach and
in the duodeum, according to Beclard, they are formed of a
fold of the mucous membrane, tufted on its margins, the trans-
verse diameter of which exceeds the length. In the jejunum
they consist of longer folds, forming semi-oval plates touching
one another at their basis. In the ileum, according to Dr. Hor-
ner, they form slightly conical projections.

— The villi can be studied to the best advantage after a minute
injection of the vessels of the mucous membranes, which by
rendering those of the villi turgid, throws them into a state of
erection, like that which takes place in the papillae of the skin
when they are in a state of functional activity. The villi of
the small intestines which will be subsequently considered,* are
peculiarly organized in some respects, apparently for the purpose
of fitting them for a function which they alone possess — that of
chylous absorption.

The Vessels and Nerves of Mucous Membranes.

— In the submucous cellular or nervous tissue, are found the
larger branches of the arteries, veins, and nerves, which ramify
finally in the mucous membranes and their villous or papillary
prominences. The vessels are derived from contiguous trunks
The veins are far more numerous than the arteres, and seem
to exceed here the large proportion which the bear to the
arteries in other portions of the body. They form, as shown
by the elegant preparations of Professor Horner, a plexus
on the surface of the membrane, which overlays the arte-
ries, and in which, when successfully injected, a straggling
arterial branch is only here and there visible. Beneath this

* See General Anatomy of Absorbent System. — v.

•

ABSORBENT VESSELS.

69

plexus, however, and mixed up with larger veins which
anastomose with the superficial venous plexus, the arteries ramify-
to a great degree of minuteness.

Of the Absorbent Vessels.

— The lacteals of the small intestines arise partly from the
villi, and partly from the surface of the intervillous mucous
membrane. Nearly all the best microscopical observers now
agree, that there are no orifices of the lacteals visible on the
villi of the intestines. The villi which are short processes, a
quarter of a line, or at most a line and two-thirds in length,
project above the surface of the mucous membrane and give to
it, when magnified, the appearance of a thick fleece. They
have various forms, cylindrical, pyramidal or lamellated. In
most of our domestic animals, they are generally flattened, broad
at the base, which runs off into a fold of the mucous membrane,
so that many of the villi appear only as a modification of the
rugae or folds of the membrane. The villi are formed exteriorly
by a coating of mucous membrane, filled within by a net-work
of minute blood-vessels, which can only be well demonstrated
by injection, and in which the lacteals take their origin by
branches anastomosing in the form of net-work. Fig. 138, is a
Fig. 138.* magnified representation of a villus, seen by
Krause, of Hanover, in the jejunum of a
young man, who had eaten a short time pre-
vious to his execution the lacteals being
found after death filled with chyle. The
mucous membrane between the villi, when
examined with a single microscope, presents
an extraordinary number of small orifices,
which are the openings of Lieberkuhn's fol-
hcles. See figs. 140 and 143.

— Neither Fohman, in his most perfect mercurial injection of
the lacteals of the intestine in fishes, nor Schwann, in the injection
of the lacteals in the intestinal villi of man, ever found any
mercury to escape into the cavity of the intestine. Hence it
may be inferred, either that there are no open orifices by

lO

OF THE NERVES AND BIUCOUS FOLLICLES.

Fig. 139.t

which they communicate with the cavity of the intestine, or
that they are so exceedingly minute, that no one has yet been
able to discover them with the microscope. The origin of the
lacteals in the villi, is, in all probability, the same as that of
absorbents in other parts of the body, by a net-work of
extreme minuteness.*

— Fig. 139, is a representation of the
origin of the absorbents from the mu-
a cous membrane of the stomach, in the
form of a net-work as they appeared
to Breschet.

— The presence of such intestinal villi,
as are found in man and the superior
animals, is not indispensible to chylous
absorption, for in a large number of
animals, the internal surface of the small intestines is destitute

of villi.:]:

Of the Nerves.

— The nerves of these membranes, are derived in many parts,
as the intestines, biliary ducts, etc., mainly from the sympa-
thetic nervous system ; hence such parts are necessarily devoid
of animal sensibility. In the stomach, upper part of the
duodenum, oesophagus, mouth, lungs, and rectum, the mucous
membrane receives branches likewise from the cerebro-spinal
system of nerves.

Of the Blennogenous or Muciferous Glands.

— These exist in great numbers in all mucous membranes, and
are the source of the mucous substance, which covers the surface
of the membrane.

* This is a doctrine long since advocated by Hewson. — p.
t fl, A layer of superficial absorbents, b, A layer more deep seated. —
I Gerber has suggested as the result of some of his microscopical operations,
that the central cell or vesicle in the columns of the cylinder epithelium, which
covers the surface of the villi as well as other parts of the membrane, commu-
nicates below with the lacteal absorbents, and assists in chylous absorption.
But this is an opinion, which requires further confirmation. — p.

lieberkuhn's follicles. 71

— The anatomy of these organs, has heretofore been hivolved
in a considerable degree of confusion, and though it is not yet
satisfactorily established, enough has been done to enable us to
make a division of them into classes, so as to render the descrip-
tion of them more intelligible.

— From the researches of recent observers, they may be
divided into two classes. The first, comprising the mucous
follicles or mucous cryptae, and mucous glands. The second
class consisting of some vesicular bodies, which may be sub-
divided into, 1st, The glandulae solitariae, (glands of Brunner,
of some anatomists,) and 2d, The so called glandulae agmina-
tse, or glands of Peyer. The mucous follicles or crypts, and
the mucous glands forming the first class are generally spread
throughout the mucous membranes, and seem to differ from
each other but little, except in regard to the degree of their
development.

— The mucous follicles are entirely microscopical ; and were
first particularly described by Lieberkuhn in the small intestines,
where they are frequently called the follicles of Lieberkuhn.
If a portion of the mucous membrane of a small intestine be
well washed, we may readily discover, by means of a simple
microscope, around the basis of the villi an extraordinary num-
ber of orifices not visible to the naked eye, which are the open-
ing of Lieberkuhn's follicles ; these openings are about eight or
ten times as large in diameter, as the red particles of the blood.*
Sometimes these openings are so close and numerous, that the
space between the orifices is scarcely so broad as the orifices
themselves ; generally, however, they are more widely sepa-
rated, in which case they give a spongy appearance to the
membrane. These follicles of the small intestines, which were
Fig. 140.* observed by Lieberkuhn, appear to be the
exact counterpart of the tubular follicles
observed in the whole extent of the mucous
X) membrane of the large intestine by Dr.
'^ Boehm, and in the mucous membrane of
the stomach by Dr. Boyd. C, Is an enlarged
view of the tubular follicles of the larse

* Mailer's Physiology, p. 260.—

72 NUJIBER OF FOLLICLES.

intestine, as they appeared in Dr. Boehm.* D, Is the natural
size of the piece magnified. They are arranged side by side
perpendicularly in the membrane, their closed or caecal bases
resting upon the subjacent cellular tunic of the intestines,
as seen at 2, which represents a perpendicular cut through the
mucous membrane, down to the cellular coat. 3, Is the surface
of the cellular coat, from which the mucous membrane has been
removed, showing the pits or depressions in which the bases of
the follicles are lodged. 1, Is the free surface of the mucous
membrane, showing the openings of the follicles which are
believed to be the same as the orifices of Lieberkuhn. In the
stomach, the cryptas or follicles alone are said to exist, except at
the curvatures, where a few of Brunner's glands are met
with ; yet in a child dead from summer cholera, the follicles
were so enlarged or hypertrophied that I could distinctly count
with the naked eye, in a square inch on the sides of the
stomach near the pylorus, a hundred and twenty-five opaque
bodies below the membrane, which presented all the usual
characteristics of the glands of Brunner in the small intestines.
In the same subject, the glands of Brunner, (duodenal mucous
glands,) were much enlarged ; and in the same extent of
surface, I counted without a glass, a hundred and seventeen
in the duodenum, ninety-five in the upper portion of the jeju-
num, and thirty-five at the commencement of the ileum.
Dr. Horner,! who is justly distinguished as an anatomical
discoverer, has made, with the assistance of Dr. Goddard, the
size and number of these follicles, the subject of attentive mi-
croscopical examination. He has found them to vary in size
in the stomach from the /gth to the ^Ijjth part of an inch in

* De Structura Glandulorum Intestinorum. Berl. 1836.

f Special and General Anatomy, vol. 2, p. 40, fourth edition.

— To Professor Horner, Dr. Boehm and Dr. Boyd, the science is much
indebted for a more minute knowledge of the structure of the mucous mem-
brane that it previously possessed. Professor Horner's interesting researches
were made upon the viscera of subjects who had died of cholera asphyxia, and
were published in the May and August numbers of the Americ. Jour, of the
Med. Sciences for 1835. — Dr. Boehm's observations were also made on the
choleric mucous membrane, and were published at Berlin in 1835; — Dr. Boyd's
at Edinburgh, in 1836. From the respective dates it would seem that Dr.
Horner led the way in this discovery. — p.

MUCOUS GLANDS. 73

diarireter, and in the colon from the J^lh to the ^l^th. He
estimates the whole number of follicles in the stomach and
intestines, at forty-six millions, nine hundred thousand, and
upwards. Of these there belong to the stomach, one million,
two hundred and ninety-six thousand ; to the small intestines,
thirty-six millions, and to the colon, nine millions, six hundred
and twenty thousand. And to the inch < square, in the sto-
mach, fourteen thousand four hundred, in the small intestines,
twenty-five thousand, and in the colon, nineteen thousand, tivo
hundred.

— The mucous glands, compared with the follicles or crypts,
are generally of considerable size, and visible to the naked eye ;
and in fact appear only to be compound cryptse. They are
little bodies placed in the submucous cellular tissue, appearing
slightly lobulated when examined with the microscope, and
containing minute cells, lined by a reflection of the mucous
membrane. These are found most abundant in parts of the
mucous membrane, where, from its exposure to acrid or irrita-
ting substances, the membrane would appear to need the most
protection from the mucous coating ; as in the mouth, the duo-
denum and the rectum.

— These glands have already been described in the trachea
bronchia, etc. They bear names in many places according to
their location, as labial, buccal, palatal, oesophageal, and duo-
denal. In the duodenum, of all places, they are most abun-
dant— where the acrid and irritating biliary secretion first comes
in contact with the mucous membrane of the alimentary canal.
To these duodenal glands alone, properly belong the term of
glands of Brunner. This anatomist (Brunner) was the first
to point them out in the mucous membrane of the duodenum,
as a series of flattened glandular granulations, studding thickly
the upper half or two-thirds of this membrane, and being as
he believed analogous in structure to the granular acini of the
pancreas. He considered them also similar in structure to the
solitary glands ; but in this respect he has been proved wrong.
Cruveilhier has observed the analogy of these glands of Brun-
ner or duodenal glands, not only with the acini of the pancreas,

VOL. II. 7

74

GLANDULE SOLITARIiE.

but with those of the different salivary glands. He found them
lo diminish gradually in number, towards the lower end of the
duodenum, so that none could be observed farther down than
the commencement of the jejunum. Dr. Boehm has verified
these observations of Cruveilhier, and shown that they are little
solid glands, formed of several minute lobules, each of which is
found to be cellular ; and that all the cells of each gland open
by a common orifice.

— The third and fourth order of glands, the glandula solitaria
and the glandulce agminatcB, (constituting the second class see p.
71,) are met with only in the alimentary canal. The latter are
almost entirely in the lower half of the small intestines : and it
has been rendered questionable by the researches of Boehm and
Miiller, whether the solitary glands of the small intestines do
not differ materially from those met with in the stomach and
large intestines.

— The solitary glands are found at the end of the small intes-
tine, in the large intestine, and a few along the lesser curvature
of the stomach. They present the appearance of small gran-
Fig. 141. ulations of the size of millet seed, which

projects slightly on the internal surface of the
mucous membrane. Neither Boehm, nor
Miiller, who has verified all Boehm's re-
searches by his own use of the microscope,
have been able to discover in the undiseased
WmmBk state, any opening to the solitary glands of
the small intestine. But when ulcerated in tubercular affections,
or in dothinenteritis, the cavity is exposed. Fig. 141, is a mag-
nified representation of one of the solitary follicles or saccuh of

the small intestines after
Boehm. It has no apparent
orifice; it is studded with
villi, and round it are seen
the orifices of Lieberkuhn's
follicles.
— In the large intestines, the orifices of these follicles are readily
discovered. B, is a representation of one of the solitary follicles

Fig. 142.

:9

HAHjjII^^

GLANDS OF PEYER. iO

of the large intestine, by the same author, in which the orifice
may be discovered in the centre, with many of the openings of
Lieberkuhn's follicles around it. A, is a vertical section of
the same follicle, showing its cavity and the orifice by which
it communicates with the interior of the large intestine.
Around it are seen the vertical tubular follicles of Boehm,
which appear to be the same as the follicles of Lieber-
kuhn.

The Glandula AgminaicE,

— Are better known under the name of glands of Peyer, after
a young anatomist who described them as well as the solitary
glands with much minuteness,* though they had previously
been pointed out by Pechlin, under the name of Vesicularum
Agmina.

— These so called agminated follicles, present themselves as
patches under a variety of forms, generally elliptical, but some-
times circular or oblong. The longest diameter of the patches
when they are either elliptical or oblong, is always parallel with
the axis of the intestines. The patches are met with of all sizes
from two to three inches in their longest diameter, to a few
lines only. They vary also in regard to number ; sometimes
fifteen or twenty only are met with in one subject, and some-
times thirty or more.

— In all cases they are found placed in the mucous membrane,
on the side over against the insertion of the mesentery. They
are found only in the small intestines, usually in the lower half,
and are most numerous near the termination of the ileon
in the colon. Peyer, however, asserts, that he discov^ered in
one instance a patch in the duodenum. These patches
appear to be formed of an agglomeration of entirely distinct
bodies, exactly analogous to the solitary glands of the small
intestines ; and in some cases where the number or size of
these agminated glands of Peyer is less than usual, the num-
ber of the solitary glands in the same region of intestine, ap-
pears to be increased.

— The appearance which these glands of Peyer present, is
* De Glandulis latestinorum. J. Conradus Peyer, 1667.— p.

76 GENERAL ANATOMY OF THE MUCOUS TISSUE.

however, in other respects very variable. Sometimes in per-
fectly healthy intestines, they can scarcely if at all be distin-
guished ; and when seen, generally appear, if held up between
the observer and the light, as little vesicles like those in the rind
of an orange, and in which no orifice can be seen even with the
glass. In tubercular disease, and especially in typhoid fever
with affection of the bowels, (dothinenteritis) they are usually
found enlarged, and ulcerated so as to expose an abrupt cellular
cavity. The structure of these solitary and agminated glands,
so different from that of the other follicles of mucous membranes,
has lately attracted considerable attention, and the researches
of Boehm* and Miillerf have rendered it doubtful, whether
they really belong to the class of follicles or not.

Fig. 143.

— Fig. 143, is part of a patch of Peyer's glands greatly magni-
fied, (after Boehm.) Here the follicles of Peyer are seen as
circular white spots, about a line in diameter, with no apparent
orifice, and surrounded with a circular zone of foramina, which
belong, as well as those scattered between the glands, to Lie-
berkuhn's follicles. Dr. Boehm tried in vain to express any
secretion from the white bodies through an external opening,
as he probably could have done, had they been follicles ; nor
was he more successful in endeavoring to force it through the
orifices forming the zone. On rupturing one of the bodies, a

* Loc. cit. — F.

t De Glandularum Secernent. Structura penitiora, etc. Leipsic, 1830. — ?.

GENERAL ANATOMV OF THE GLANDULAR SYSTEM. I t

cavity was opened similar in extent to the white body itself,
in which was found a grayish white mucous matter, composed
of particles smaller than the ordinary particles of mucus. Ac-
cording then to Boehm and Miiller, there are not, in the
healthy state, in the patches of the so called Peyer's glands,
any large follicles with open mouth or cells, but merely sacculi,
the nature of which is unknown.

— Fig, 141, p. 74, is a representation after Boehm, of one of the
solitary glands of the small intestines too often confounded
with the glands of Brunner, and which is precisely similar
in structure and appearance, to one of the bodies in the patches
of Peyer, with the exception that its surface is more thickly
studded with villi.* —

General Anatomy of the Glandular Tissue.

Any original structure that discharges from the blood-vessels
a fluid different from those which they naturally contain, may
be considered as glandular. The function or process by which
such fluids are derived from the blood-vessels is called secre-
tion.

A structure of this kind seems to exist in very different
situations : for it is distinctly circumscribed in many of those
bodies commonly denominated glands, which are of a very
precise form ; and it is also diffused on some very extensive
surfaces. The gastric liquor, a most important secretion, is
probably discharged from the vessels which open, like exha-
lents, on the internal surface of the stomach,f and not from any
circumscribed bodies, which are generally denominated Glands.

The name of gland is theoretically applied to several bodies
which cannot be proved to secrete any fluid whatever ; and
also to those bodies connected with the absorbent vessels, which

* Each of the white bodies of the glands of Peyer as well as the solitary
glands, were considered by Boehm, not as glands or follicles, but closed vesicles.
More recently, however, Krause of Hanover, and Dr. Allen Thompson, have
occasionally found them provided with open orifices, independently of disease.
— p.

t The gastric juice is now with greater probability, believed to be a secre-
tion from the tubular follicles of the stomach. — p.
7*

78 GENERAL ANATOMY OF THE GLANDULAR SYSTEBT*

are called the Lymphatic Glands ; but it is most commonly
appropriated to those organs which discharge a fluid different
from the blood.

The structure by which mucus is secreted in some places,
appears to be very simple. Thus, in the Schneiderian mem-
brane and the urethra, there are small ducts from four to six
lines in length, and equal in diameter to a bristle, which appear
to be formed of the membrane on which they open. From
these ducts mucus issues to cover the surface of these mem-
branes. In many instances there is no substance resembling
that of the circumscribed glandular bodies, connected with
these ducts ; but the secreted fluid seems to be discharged into
the ducts from the small vessels on their surfaces. The ducts
of this nature in the urethra are denominated Lacuna.

In some other parts of the body, the cavities into which
mucus is discharged are somewhat different, both in form and
size, from those above mentioned, and are called Follicles,
These cavities are surrounded with more or less of a pulpy
vascular substance, which has been considered as glandular, and
essential to the mucous secretion.

The circumscribed bodies, which are commonly called glands,
differ in their internal appearance and texture, from the other
parts of animals. The substance of which they consist differs
very much in the different glands ; and thus renders the liver,
kidneys, salivary glands, mammae, &,c., very different from each
other. Some glands, as the salivary, &c., are composed of
several series of lobuli that successively diminish. The smallest
of these are denominated Acini. Each of them is connected
by a small artery and vein, to the large blood-vessels of the
glands ; and also sends a branch to join the excretory duct.

These Acini are therefore connected to each other, by the
blood-vessels and excretory duct of the gland, and also by the
cellular membrane which covers them externally, and occasions
them to adhere to each other where they are in contact. In
consequence of this structure, these glands have a granulated
appearance.

The liver, when incised with a sharp instrument, appears
differently ; but when broken into pieces, it seems to consist of

GENERAL ANATOMY OF THE GLANDULAR SYSTEM. 79

small acini. Some other glands, as the Prostate, appear to be
uniform in their texture, and have none of this granulated
appearance.

The structure of glands has long been an interesting object
of anatomical inquiry, and was investigated with great assiduity
by those eminent anatomists, Malpighi and Ruysch.

Malpighi, as was formerly observed, used ink and other
colored fluids in his injections. He was also very skilful in
the use of microscopes, and took great pains in macerating and
preparing the subjects of his inquiries. Ruysch, on the other
hand, used a ceraceous injection, and was most eminently suc-
cessful in filling very small vessels with it. Malpighi believed
that there were follicles or cavities in glandular bodies, which
existed between the extremities of the arteries and the com-
mencement of the excretory ducts of those bodies, and that in
these cavities the secreted fluids underwent a change. — Ruysch
contended, that the arteries of glands were continued into excre-
tory ducts, without the intervention of any cavity or follicle ;
that the small bodies which had been supposed to contain folli-
cles or cryptae, were formed by convolutions of vessels, and that
the change of the fluid, or the process of secretion, is produced
by the minute ramifications of the artery.

A very interesting account of this subject is contained in two
celebrated letters, which passed between Boerhaave and Ruysch
in the year 1721, and are published at the end of the fourth
volume of the works of Ruysch.

The opinion of Ruysch has been more generally adopted by
anatomists, and has derived support and confirmation from
several anatomists since his time. The late Mr. Hewson
declared his conviction that the small globular bodies which
are scattered through the kidneys, and were supposed to be
follicles or cryptae, are merely convoluted arteries. He also
asserted, that the acini which appeared in the mammae as
large as the heads of pins, when the excretory ducts of that
gland were injected with vermillion and painter's size, proved
to be the minute ramifications of the excretory duct, which

80 GENERAL ANATOMY OF THE GLANDULAR SYSTEM.

divided very suddenly into branches so small that they could not
readily be seen by the naked eye.*

Notwichstanding these reasons for supposing that the excre-
tory ducts of glands were derived simply from the arteries of
those bodies, it is said that the late Dr. W. Hunter used to
declare his belief, that there was a part in glands which was not
injected in his preparations ; and to say farther, that he
believed his preparations were injected as minutely as those of
Ruysch.

All of these opinions have been strenuously controverted by
the Italian anatomist, Mascagni, who believes that the arteries
terminate only in veins ; and of course that they neither form
exhalent vessels, nor communicate with the excretory ducts of
glands. His idea of the structure of glands is different from
those either of Malpighi or of Ruysch.

He supposes that glands contain a great number of minute
cells ; that the arteries, veins, and absorbent vessels are spread
upon the surface of these cells, in great numbers, and very
irregularly. From these cells very small canals originate,
which unite to form the small branches of the excretory ducts.
According to his idea, the secreted fluid is discharged through
pores or orifices of the blood-vessels, into the cells, and proceeds
from them through the canals, into the branches of the excretory
ducts. Absorbent vessels, in great numbers, originate from these
cells.

In his great work on the absorbent system, when treating on
the termination of arteries and the commencement of veins,
(Part I, Section 2,) he asserts, that if the kidneys are success-
fully injected with size, colored with vermillion, and then
laid open by a section of a razor, it will be found that the size
without the color has passed into cells which are very numerous ;
that the arteries and veins are ramified most minutely on the
surfaces of these cells, and that the tubuli uriniferi, as well as
the absorbent vessels, originate from them.

He supposes that a considerable portion of the fluid thus

■* See Experimental Inquiries, vol. ii. p. 178.

GENERAL ANATOMY OF THE GLANDULAR SYSTEM. 81

passing off from the blood-vessels, is commonly taken up by
the absorbent vessels of the kidneys : for in two cases in which
he found the absorbent vessels obstructed, a diabetes existed,
which he considered as the effect of the inactivity of the
absorbents. He asserts, that in the liver, pancreas, mammae,
and also in the salivary and lachrymal glands, the minute
arteries and veins are also distributed upon the surfaces of
cells ; and that very small canals arise from these cells, and
unite to form the small branches of the excretory ducts.

This great anatomist appears to have been much occupied
with microscopical observations, and has gone largely into the
discussion of this subject.*

— The opinions of the distinguished anatomists which have
been detailed above, conflict, as has been seen, considerably
with each other. They were, however, legitimate deductions
from their own experiments and observations, and each
entitled to credit, since every one of these great men has added
considerably to the knowledge of this interesting and intricate
department of general anatomy. Since their time, other
observers have contributed much to the elucidation of the
structure of different glands, of whom we shall hereafter have
occasion to speak ; and lastly, Professor Miiller has published a
work, ex professo,\ upon the subject, which has reconciled many
of these conflicting opinions. This observer has extended his
investigations into the comparative anatomy of all the glands,
and to their development at the different stages of fcEtal life, and
having a full acquaintance with all that had been previously
discovered, his researches may be looked upon as classical upon
this subject.

* The late Dr. W. Hunter, in his Medical Commentaries, (p. 40,) avowed
his belief, that the fluids which appear occasionally in the various cavities of
the body, transude through the coats of the blood-vessels. Mr. Hevvson, (Ex-
perimental Inquiries, Vol. II. Chap. 7,) suggested several reasons for dissenting
from this opinion; but Mascagni has endeavored to support it. — See a long
note to the above mentioned section of this work, page 74.

f De Glandularum Secernentium Struclura Penitiore, earumque prima for-
matione, etc. Leips. 1830. — p.

82 GENERAL ANATOMY OF THE GLANDULAR SYSTEM.

— Of all the various opinions entertained, that of Malpighi
according to Miiller, was nearest the truth ; viz. that the elemen-
tary parts of all glands, the so named acini or granules, have
the same structure as the simple and compound follicles or folli-
cular glands, each one consisting of several minute, roundish
sacs, which receives its secretion from the blood-vessels distributed
on its walls, and which secretion is poured out through the
efferent duct. But these cavities, which Malpighi believed to
be single elementary follicles, and Mascagni and Cruikshank
simple cells, have been shown by Miiller, to consist of an aggre-
gation of many minute ramifications of the duct, which terminate
by closed or ccecal pouches, as is seen in fig. 144, upon which
the vessels ramify, and which constitute the real elementary parts
of the gland.

— The individual forms, which these mi-
nute ramifications of the secretory ducts
assume, vary, however, somewhat in the
different glands, though they are alike in
the general result ; that of forming an in-
dependent system of tubes, ramifying so
as to gain a great extent of surface for
.. t- t a their lining membrane. The finest se-

ff-^iS^i ^ *^ creting tubes, which are closed at their

extremities like the follicles of the simple mucous membranes,
are never, however, as has been proved by microscopical mea-
surement, so minute as the compound follicle, in which there
is a single duct common to several exceedingly minute follicles
of the simple kind ; which seem to be formed by the amplifica-
tion of the surface of a simple follicle, depressed on its sides
into a number of cellular dilatations which open through the
common duct. Specimens of these, are to be found in the
Meibomian glands, the tonsil, labial, buccal, duodenal glands,
etc.
— In other more complicated glands, is found a further devel-

* This is a magnified representation after "Weber, of a portion of a parotid
gland. The smaller figure is the natural size of the piece magnified, a, The
cells clustered on the extreme branches of the duct of Steno. — p.

GENERAL ANATOMY OF THE GLANDULAR SYSTEM.

83

opment of ihe follicular sac, and \\\& excretory tube. In these
compound or conglomerate glands, such as the lachrymal,
mammary, salivary glands, pancreas, liver, etc., the excretory
tube is longer and ramifies in the manner of a tree. In some,
the tubes ramify with a certain degree of regularity, as in the
mammary gland, represented in the following figure. In some
as in the tubular glands, the kidneys and testes, the tubes
which begin as blind sacs on the periphery of the organs, are
tortuous, looped and convoluted at their commencement, and
often at the same time inextricably intervolved with the capillary
blood-vessels, lymphatics and nerves.
Fig. 145.*

— The divisions given off by the main duct of a conglomerate
gland divide again by giving off side branches ; these divide
and subdivide in like manner in their turn, till finally, a subor-
dinate branch of minute size terminates in a cluster of blind
pouches or follicles, which are invested on their outer face by
cellular tissue, and capillary vessels, and form one of the
acini or granules of a gland. A collection of these acini, which
correspond to a particular division of the excretory duct, will
necessarily be a little separated from other parts of the gland,
and is called a lobule. This is the arrangement in all the

* The diameter of the cells or terminal cavities of the lactiferous ducts, is
large, compared with those of many other glands ; it is from ten to thirty-five
times greater, according to Mailer, than that of the smallest capillary vessels
in the human body. — p.

84 GENERAL ANATOMY OF THE GLANDULAR SYSTEM.

lobulated glands, viz. the lachrymal, mammary, salivary
glands, and the pancreas. Each acinus is not therefore, as was
supposed by Malpighi, Ruysch, and Mascagni, a single cell,
but a cluster of cells, too minute to be seen, except in the dis-
tended state and by the aid of the microscope, seated upon the
extremity of a minute branch of the excretory tube, and sur-
rounded by a net-work of capillaries, exactly analogous in
structure to one of the mucous glands of the mouth, or of the
duodenum. Sometimes, instead of the short cells of the acini,
the ducts terminate in long excretory tubes, as in the kidney
and testis, when the length of the tube compensates in regard
to the extent of secretory surface, for the nondivision into cells.
— In some glands, as in the liver of man and all the vertebrate
animals, and in the kidneys of oviparous animals where there
is a portal circulation and the secretion is made from venous
blood, the arrangement is somewhat peculiar. The ducts
ramify irregularly, present no arborescent arrangement, and
there is no distinct division into separate lobules. The excre-
tory ducts terminate in the acini, in the form of tufts of micro-
scopical tubes, which anastomose together so as to form a sort
of net-work in the body of the acinus : the centre of each aci-
nus, in the peculiarly constructed gland called the liver, being
occupied by a vein, according to Kiernan,* which carries away
the blood of the portal system, after its excrementitious parts
have, by the secretory action, been transferred to the branches of
the excretory duct in order to be thrown into the duodenum as bile.

Capillary Blood- Vessels.

— The excretory ducts of the liver and kidneys are considered
the most minute; yet these have a diameter two or three times
as large as the minute arteries and veins, which may be seen with
the microscope, ramifying on the ducts and forming a capillary
net-work on their walls and interstices, and from which the
fluids are distilled into the cavities of the tubes, modified in
different parts, so as to constitute the peculiar secretions.
Thus, in the kidney and testis, the ducts are arranged in con-

* See Anatomy of Liver. —

MICROSCOPICAL MEASUREMENTS.

85

volutions and terminate abruptly in a cul de sac ; in the pan-
creas, salivary and mammary glands, etc., they have an arbor-
escent arrangement, and terminate in grape-like clusters of cells;
the general fact of the distribution of these vessels upon their
walls, and the mode in which secretion is effected being much
the same in all. There is no inosculation or direct termination
of a blood-vessel in a duct as Ruysch supposed, and the experi-
ments that have given rise to this opinion, that of passing a fluid
by forcible injection from a secretory duct into a blood-vessel, or
vice versa, have been attended by a rupture of the fragile struc-
ture of the glands, by which the injection has mechanically in-
sinuated itself from one system of vessels into the other.
— The simplest form of gland, is that of a mere depression or
recess in the surface of a membrane, as the sebaceous follicles
of the skin or cryptae or follicles of the raucous membrane.
These have but a simple orifice, or a short duct. The next
degree of complication in the structure of glands, is that of the
cellulated or compound follicle, and its highest degree of deve-
lopment is met with in the conglomerate glands, as the parotid,
the mammary, and the liver.

Microscopical Measurement of the Diameter of the Capillary
Vessels, and Ultimate Divisions of the Excretory Tubes m
some of the Glands.

Capillary blood-vessels, according to Weber,
" " in the kidneys, " Miiller,

The smallest pulmonary air-cells in the human sub-
ject, (Weber,) which have a termination some-
what like the ducts of glands, _ _ _
Tubuli uriniferi in the cortical substance of the
human kidney, (Weber,) - _ _ _
" " in the pyramidal portion,
" " in the papillae, _ _ -
Tubuli seminiferi of man, (Miiller,) - - -

" " distended with mercury,
Tubuli recti testis, (Lauth,) (undistended,) -
Cells of the Meibomian glands, (Weber,)

VOL. II. 8

Parts of an Inch

J— to

S700 "■"-' ISOO

to —-

to

923

I

195

to

86 ACTION OF GLANDS.

It must, nowever, be acknowledged, that no information which has as yet been
obtained respecting the structure of glands, enables us to explain their won-
derful eflect upon the fluids which pass through them. It remains yet to be
ascertained why one structure forms saliva and another bile ; or why so
much ap})aratus should be necessary for the secretion of milk when adipose
matter appears to be produced by the mere membrane in which it is
contained.

Dr. Berzelius, professor of Chemistry at Stockholm, in a work on animal
chemistry, asserts, that if all the nerves going to a secretory organ are divided,
secretion will cease, notwithstanding the continued circulation of the blood.
From this, he thinks, that secretions depend upon the influence of nerves,
although he cannot explain their effects.

Mr. Home, after relating some experiments upon blood and serum, made with
the Voltaic Battery, proposes the following questions, among others: Whether
a weaker power of electricity than any which can be kept up by art, may be
capable of separating from the blood the different parts of which it is com-
posed ; and forming new combinations of the parts so separated ? AVhether
the structure of the nerves may enable them to possess a low electrical power,
which can be employed for that purpose ? &c.

See the London Philosophical Transactions, for 1809, part II.*

* Mr. WoUaston has also publislied a small paper on this subject, in the Philosophical
Magazine, vol. 33.

:^;^/:^^

THE LIVER. 87

CHAPTER III.

OF THE LIVER, THE PANCREAS, AND THE SPLEEN.

Of the Liver.

This largest viscus of the abdomen, when in a healthy con-
dition is of a reddish brown color. If it is taken out of the
subject, and laid on a flat surface, it is flat, but in the abdomen
it is convex and concave.

It is situated in the right hypochondriac region, which
it occupies entirely ; and extends through the upper portion of
the epigastric into the left hypochondriac region. Being placed
immediately under the diaphragm, and in close contact with it,
as well as with the inner surface of the right hypochondriac
region, it partakes of their form, and is convex above and con-
cave below. When thus situated, it is of an irregular figure,
between the circular and the oval, but is broader at the right
extremity than at the left, and very irregular in thickness. The
edge or margin which is in contact with the posterior part of the
right hypochondriac region, is very thick. It gradually becomes
thinner towards the left, and also towards the front ; so that the
right margin, and a large portion of the posterior margin, is very
thick, while the left and anterior margin is thin.

The upper convex surface of the liver, when in its natural
situation is smooth : the lower concave surface is marked by
several grooves or fissures and eminences. One of these, called
the Umbilical or the great fissure, commences at a notch in
the anterior edge of the liver, to the left of the middle, and con-
tinues to the posterior edge. At the commencement of this
fissure the umbilical ligament enters ; and at the termination,
or near it, the vena cava is situated. Opposite to this fissure,
on the upper or convex surface, is a ligament passing from the
diaphragm to the liver, which is called the falciform. The

88 LOBES AND FISSURES OF THE LIVER.

fissure and the ligament divide the liver into its two great lobes,
the Right and Left.

Another great fissure, called the transverse or principal,
commences on the right lobe and extends to the left, crossing
the first mentioned fissure at right angles, and extending a very
short distance beyond it. It is very deep and rather nearer to
the posterior than the anterior edge of the liver. In this fissure,
near to its right extremity, the great vein, called vena portarum,
and the hepatic artery enter, and the excretory duct of the
liver, commonly called the hepatic duct, comes out. About the
middle of the fissure are two prominences, one on each side ;
these were called the portae, or gates of the liver, and hence the
great vein was called vena portarum. This vein has two very
large rectangular branches, which constitute what is called the
sinus of the vena portarum ; and they occupy the principal
extent of the fissure.

The liver is in close contact with the vena cava behind ; and
there is either a groove in it for the passage of the vein, or this
great vessel is completely enclosed by it. There is also
an excavation on the lower surface of the liver, which is occu-
pied by a portion of the gall-bladder.

Besides the great lobes above-mentioned, there are also two
or three prominent parts, in the concave surface, which are
denominated lobes. One of these, called Lohulus Spigelii, is
oblong, with two sides, and an angle continued along its whole
length, which extends from the transverse fissure on the posterior
margin of the liver. It is situated between the posterior part
of the transverse fissure, or ductus venosus, and the vena
cava.

The anterior extremity of this lobe, which forms one of the
margins of the transverse fissure, is somewhat bifurcated, and
has been called lobulus caudatus. The largest portion of the
bifurcated end forms a process like a papilla, and is one of the
portae.

Between the umbilical fissure and the depression for the
gall-bladder is a protuberant space, which varies from an inch
and a quarter to two inches in breadth. This has also been

LIGAMENTS OF THE LIVER.

89

called a lobe, Lobulus Q^uartus or Anonymous ; its posterior
point, opposite the papilla of the lobulus spigelii forms the other
porta of the liver.

The peritoneum is extended from the surface of the abdo-
men to the surface of the liver, in such manner as to cover it,
and to form ligaments, which have a great effect in retaining
it in its proper situation. The whole posterior edge of the
liver is in contact with the back of the abdomen. The perito-
neum above the liver is reflected to the upper surface of it,
and the peritoneum below it to the lower surface ; so that two
lamina of the peritoneum pass from the lower part of the
diaphragm at the back of the abdomen to the posterior edge
of the liver. These processes of the peritoneum are considered
as forming two ligaments, which are called the right and left
lateral ligaments. A portion of the posterior surface of the

Fig. U6.*

liver, uncovered by the peritoneum, is often in contact with a
portion of the tendon of the diaphragm, also uncovered by peri-
toneum : around this place of contact, the peritoneum is extend-
ed from the diaphragm to the liver, and thus forms what has
been called the coronary ligament of the liver.

* The upper surface of the liver. 1. The right lobe. 2. The left lobe. 3.
The anterior or free border. 4. The posterior or rounded border. 5. The broad
or suspensory ligament. 6. The round ligament. 7, 7. The two lateral liga-
ments. 8, 8. The space left uncovered by the peritoneum, and surrounded by
the coronary ligament. 9. The inferior vena cava. 10. The point of the
lobulus spigelii. 3. The fundus of the gall-bladder, seen projecting beyond the
anterior border of the right lobe.
8*

90 MODE OF SUPPORTING THE LIVER.

The peritoneum of the right side of the diaphragm, and of the
abdominal muscles, as far down as the umbilicus, is extended
to the liver, and joins it on the convex surface immediately
opposite to the umbilical fissure. The peritoneum from the
left side of these parts does the same ; and as these reflections
of the peritoneum are continued from so low a part as the
umbilicus, they are extended not only to the convex surface
of the liver, but also to the great notch, and along the umbilical
fissure.

From the umbilicus proceeds a round cord-like ligament,
which in the foetal state was a vein, that passes to the great
fissure of the liver, and along it. The process of the perito-
neum above mentioned is so connected with this cord, that it
encloses it in its lower edge, and the whole is called the falci-
form ligament of the liver. The cord, when named separately,
is the umbilical or the round ligament ; and the membrane or
lamina of the peritoneum forms the suspensory ligament.
Besides these, the peritoneum on the lower side of the liver is
so arranged, that it not only extends to the stomach, but to the
duodenum and the colon.

By these ligaments the position of the liver must be fixed to
a great degree ; and there is one additional connexion, which
must have a great effect in retaining it in its proper situation.
The vena cava receives two or three great veins from the liver,
(vencB cavce hepatic<s,) at the place where it is in contact with
the posterior edge of that viscus : these veins of course pass
directly from the substance of the liver into the cava, and
connect it to that vessel. As the cava is supported by the heart,
and also by the diaphragm, it must afford a considerable support
to the liver.

When the stomach and intestines are distended, they must
also contribute in a considerable degree to the support of the
liver.

The liver has a strong tendency, when we are erect, to change
its situation ; and some considerable support is necessary to
counteract this tendency. It would move to the right, when
we lie on the right side, if it were not in contact with the ribs :

VESSELS OF THE LIVER. 91

and it inclines to the left, for want of such suppoi / when we
lie on the left side.

It has been computed, that the liver descends about two
inches, when the position of the subject is changed from the hori-
zontal to the erect. As it is in contact with the diaphragm, it is
obvious that it must be influenced by the motions of that muscle,
and that it must descend when the diaphragm contracts.

The liver is composed of a substance which has some firm-
ness of consistence, although it is yielding ; and is also some-
what brittle or friable.* When cut into, the sections of many
tubes, or vessels of different diameters, appear on the cut
surface. When the texture of this substance is more closely
examined, it appears somewhat granulated, or composed of
very small bodies, which were called acini by the anatomist
who first described them. The whole substance is enclosed
by the peritoneum, which is extended to it from the surface of
the abdomen in the manner that has been already described.
It has also a proper coat or capsule ; and on the posterior edge,
where the lamina of the lateral ligaments pass from the dia-
phragm to the liver, at some distance from each other, a portion
of the liver, covered by this coat and by cellular substance, is
in contact with the diaphragm. The same thing occurs likewise
at the coronary ligament.f

The liver holds the first place among the glands of the body
for size, but it is still more remarkable for some other circum-
stances in its economy. In addition to an artery, which passes
to it as arteries do to other glands, there is a large vein, (vena
portarum,) which also enters it as an artery ; and after rami-
fying throughout the liver, communicates, as does the artery,
with other veins, which carry the blood from this gland into
the vena cava and the general circulation. There are therefore
three species of blood-vessels in the liver ; and with these are

* It has been fractured in the living body by external violence.

■f Many anatomists deny the existence of this coat ; but if one of the lamina
of the ligaments be carefully peeled off from the surface of the liver which is
slightly affected by putrefaction, it will be apparent, although very thin. It
was described by M. Laennec, in Le Journal de Medicine for 1803.

92 HEPATIC ARTERY.

found the vessels which carry out of the gland the fluid secreted
by it, or the bile.

The artery of the liver is denominated the Hepatic Artery.
The vein which goes to the liver is called the Vena Portarum,
from tlie place at which it enters. The veins which carry to
the vena cava the blood brought to the liver by the hepatic
artery and the vena portarum, are called the Hepatic Veins ;
and the duct through which the bile flows out of the liver, is
called the Hepatic Duct. Three of these vessels, the Hepatic
Artery, the V^eria Portarum, and the Hepatic Duct, enter the
liver at the great fissure, at the spot where the prominences
exist called the portae ; hence the name vena portarum was
applied to the vein.

These vessels ramify in the manner presently to be described ;
and it is ascertained by minute anatomical investigation, that
the liver is entirely composed of the ramifications of these ves-
sels and of the hepatic veins, with absorbent vessels and nerves,
which are connected together by cellular membrane.

It has been already observed, that the first great branch sent
off by the aorta in the abdomen, the C<zliac, divides into three
branches, which go respectively to the stomach, the liver and
the spleen.

The hepatic is generally the largest of these branches. In its
progress towards the liver it sends off an artery to the stomach,
called the gastrica dextra. At the great fissure it divides into
two branches : the right branch, which supplies the right lobe
of the liver, is of course the largest. This branch sends off one
to the gall-bladder, which is called the cystic artery ; and also
some smaller branches : it passes under the hepatic duct, and
ramifies through the great lobe of the liver. The left branch
is distributed through the left lobe of the viscus. It can be
proved by injection, that the hepatic artery communicates not
only with the hepatic veins, but with the biliary duct, and the
vena portarum also. It has been disputed whether the size of
this artery is greater than would be requisite for the nourishment
and animation of the liver.

Vena Portarum, the great peculiarity of the liver, originates

Mhii-li^iliailii

VENA PORTARUM. 93

from all the chylopoietic viscera except the liver, and is
of course formed by the union of the veins which correspond to
all the branches of the coeliac and mesenteric arteries, as they
are distributed to the stomach and intestines, the spleen, the
pancreas, and the omentum. The veins from the intestines
generally form two great trunks, which are denominated
the greater and lesser mesenteric veins. The great mesenteric
vein is situated to the right, and rather before the mesenteric

Fig. 147.*

/'

\

artery. — After it has approached the origin of the artery, it
separates from it, and passes behind the pancreas : at this place,
nearly in front of the spine, it is joined by the great vein of the
spleen, which forms almost a right angle with it, and these
constitute the great trunk of the vena portarum. The lesser
mesenteric vein, which corresponds to the inferior mesenteric
artery, and brings blood from the pelvis and from the left part

* The under surface of the liver. 1. The right lobe. 2. The left lobe. 3.
The lobus quadratus. 4. The lobulus Spigelii. 5. The lobulus caucTalus. 6.
The longitudinal fissure, in which is seen the rounded cord ; the remains of the
umbilical vein. 7. The pons hepatis. 8. The fissure for the ductus venosus ;
the obliterated cord of the ductus is seen passing backwards to be attached to
the coats of the inferior vena cava 9. 10. The gall-bladder lodged in its fossa.
11. The transverse fissure, containing from before backwards, the hepatic
duct, hepatic artery, and portal vein. 12. The vena cava. 13. A depression
corresponding with the curve of the colon. 14. A double depression produced
by the right kidney and its supra-renal capsule. 15. The rough surface on the
posterior border of the liver left uncovered by peritoneum ; the cut edge of
peritoneum surrounding this surface forms part of the coronary ligament. 16.
The notch on the anterior border, separating the two lobes. 17. The notch on
the posterior border, corresponding with the vertebral column.

94 VENA PORTARUM. HEPATIC DUCT.

of the colon, becomes finally a large vessel, and commonly
unites with the splenic about an inch and a half before its
junction with the superior mesenteric vein. The vena porta-
rum, thus formed, proceeds towards the liver, inclining to the
right, and is generally about three inches in length : in
its course it sometimes receives small veins, which in other cases
pass to its splenic and mesenteric branches. When it has
arrived at the great transverse sinus of the liver, it divides into
two large branches, each of which forms nearly a right angle
with it. Their size is so great, that, when distended with
injection, they appear like an independent vessel, into which
the vena portarum enters ; and on this account they are called
the Great Sinus of the vena portarum. They do not adhere
firmly to the glandular substance of the liver, but are united to
it by cellular membrane. The right branch is the widest and
shortest. It generally divides into three branches; an anterior,
a posterior, and a lateral branch ; which ramify minutely, and
extend themselves in the right lobe. The left branch is much
longer, and continues to the extent of the transverse fissure.
Near its termination it is joined by the umbilical ligament,
which has been already mentioned. This branch is generally
in contact with a branch of the hepatic artery, and of the hepa-
tic duct ; and ramifies like the right branch, into the contiguous
parts of the liver.

The Hepatic or excretory duct originates, by very small
vessels, from the acini or corpuscles of which the liver is com-
posed, and into which the minute ramifications of the vena
portarum and hepatic artery extend. They accompany these
vessels, increasing as they increase, although the fluid they
contain moves in an opposite direction ; and two large branches
which they ultimately form are situated at the portae of the
liver, in contact with the great branches of the vena portarum
and the hepatic artery.

These three vessels are in contact with each other before
they enter the liver. The biliary duct is anterior, the vena
portarum posterior, and the artery to the left of them. They
are accompanied by nerves and lymphatic vessels, and are

HEPATIC VEINS. NERVES OF THE LIVER. 95

surrounded by a considerable quantity of cellular substance,
and thus arranged are partially covered with peritoneum. The
cellular substance which invests them continues with them into
the liver, and is more particularly connected with the vena
portarum. It is called Glisson^s Capsule, and was supposed
to have some contractile power, which assisted the circulation
of the vena portarum ; but that idea is now altogether abandon-
ed. The hepatic v^eins, which receive the blood of the hepa-
tic artery and the vena portarum, open into the anterior part
of the vena cava, where it is in contact with the liver. Gene-
rally there are three of these veins, but sometimes there are
only two ; in which case one of them is formed by two others,
which unite immediately before they open into the vena
cava. It is to be observed, that the various branches of these
veins do not accompany those branches of the vena portarum
or hepatic artery to which they correspond, but form very
large angles with them. This is probably owing merely to
their termination in a part so distant from that in which the"
artery and the vena portarum originate ; but it is very different
from what occurs in other glands.

The Nerves of the Liver are derived from the semilunar
ganglions of the splanchnic nerves. From these many nerves
proceed, which form a net-work denominated the solar plexus.
From this plexus many threads are sent off, which form a net-
work that is divided into the right and left hepatic plexus.
These plexuses surround the hepatic artery and the vena por-
tarum, and accompany them in their ramifications throughout
the liver, being enclosed by Glisson's capsule. They receive
some threads from the stomachic plexus, formed by the par
vagum. Although the number of nervous fibres is very con-
siderable, their bulk, compared with that of the liver, is very
small.

The Lymphatics of the Liver are extremely numerous ; and
those in that portion of the peritoneum which invests the liver
may easily be rendered conspicuous : for by pressure the in-
jected fluid can be forced from the trunks and large branches
into the small ramifications, in opposition to the valves. When

96

GLAfJDULAR SUBSTANCE OF THE LIVER.

all the surface is injected in this manner, it has the color of
the substance injected ; as is the case with parts which are very
vascular, when the blood-vessels are injected.

The deep-seated lymphatics are also very numerous in the
liver, and communicate freely with the superficial.

The superficial lymphatics, which are on the upper surface,
proceed through the diaphragm into the thorax in their course
to the thoracic duct. Those which are deep-seated emerge
from the liver at the portae, where the great vessels enter, and
unite with the thoracic duct in the abdomen, after passing
through several glands. The lymphatics of the lower surface
unite with the deep-seated.

The glandular or parenchymatous substance of the liver is
of a reddish-brown color, and moderately firm consistence.
When it is cut into, the cut surface exhibits the sections of the
branches of the different blood-vessels above mentioned, and of
the excretory ducts. These vessels are often distinguishable
from each other. The section of the biliary duct appears the
thickest ; that of the artery next ; the vena portarum is next in
order; and, last of all, the venae hepaticae.

The branches of the vena portarum are surrounded by cellu-
lar substance, or Glisson's capsule ; and, therefore, adhere less
to the substance of the liver than the branches of the hepatic
veins. The sections of the hepatic ducts have often bile in
them, and are, therefore, termed pori biliarii. The branches of
the artery are also very distinguishable.

When the Internal substance of the liver is brought into
view, and examined accurately, it appears to be formed of
small bodies, or acini, which are distinguishable from each
other. If the liver happens to be torn or lacerated, the lacer-
ated surfaces are rough and irregular, owing to the separation of
these acini from each other.*

* The acini are so named from a fancied resemblance to grape or raisin seeds.
Between these acini, there is usually a minute quantity of fatty matter, the
existence of which is proved by the destructive analysis of the organ. In
tubercular phthisis, especially in females, it occasionally accumulates so as to
form what is called the fatty liver, which presents a mottled appearance, and
resembles much the livers of the shark, cod, and other oily fishes. — p.

OF THE ACINI. 97

It is asserted by several microscopical observers, that a minute
branch of each of the aforesaid vessels can be traced into each
of the acini. It is also declared, that if each of these vessels
be injected separately with mercury, oil of turpentine colored,
or a saturated aqueous solution of gutta gamba, there is no part
of the glandular mass as large as a grain of mustard seed in
which those vessels will not be found.

Several anatomists of the first character have likewise declared,
that a fluid properly injected into one of these vessels, will occa-
sionally pass into all of them. Thus an injection will not only
pass from the vena portarum to the biliary duct, but to the hep-
atic artery and veins also. It will likewise pass, in a retrograde
course, from the biliary ducts to the vena portarum, and to the
hepatic artery and the hepatic veins ; or from any one of the
four orders of vessels into the three others.*

The great peculiarity of the liver is, that venous blood,
instead of arterial, is brought to it for the purpose of secretion.
Thus the great vein of the chylopoietic viscera, instead of
passing to the cava, enters the liver by the transverse fissure,
and takes on the office of an artery ; its coats, on this account,
being much thicker and stronger than those of the hepatic
veins.f

— The acini, when isolated from the surrounding granulations,
and examined with a simple microscope, appear evidently to be
ovoid or rather polyhedrical bodies, with five or six facets, so
arranged as to fit exactly to the facets of the surrounding acini,
leaving no interval between them, except that occupied by the
intervening delicate cellular tissue, which is an extension from
the capsule of Glisson.

— Miiller, in a few cases succeeded in injecting the biliary
canals from the hepatic duct, with size colored with vermilion

* I have tried the experiment, and find the assertion to be correct. — h.

f A case is related by Mr. Abernethy.. in the London Philosophical Transac-
tions, in which the vena portarum terminated in the vena cava below the liver,
■without communicating with it. The hepatic artery was the only vessel which
carried blood to the organ, and was unusually large, the liver being nearly of
the natural size. Some bile was in the gall-bladder, but it was less acrid than
usual.

VOL. II. 9

98

KIERNAN ON THE MINUTE

SO as to make the liver quite red. The minute acini then
appeared to him to be formed chiefly of ramified divisions of
the bihary ducts, terminating in the acini in a tuft of vessels,
which divide without diminishing in size, and anastomose to-
gether so as to form a net-work. They lie close together, and
are difficult to be discovered, even with the microscope ; their
diameter varies according to Miiller, from gljth to ^^^ih part
of an inch, but is greater, however, than that of the capillary
vessels.

— According to Kiernan,* who has investigated this subject
with much care, the small granular bodies, so well known to
anatomists in the liver under the name of acini, should be

Fig. 148. t

called lobules, inasmuch as they are found when examined
under the microscope, to be apparently composed of numerous
smaller bodies, colored yellow most generally by the bile
which they contain. Each of these lobules of Kiernan, (acini

* Kiernan, on the Anatomy and Physiology of the Liver, Philosophical
Transactions of the Royal Society of London, for 1833. — p.

f Fig. 148, represents the interlobular ducts, entering the lobules, and forming
the lobular biliary plexuses, a, Two lobules, b, b, b, Interlobular biliary ducts.
c, c, c, The interlobular cellular tissue, d, d, The external portions of the
lobular biliary plexuses injected, e, e, The intralobular branches of the hepatic
vein. /,/, The uninjected central portions of the lobules. Mr. Kiernan, h!is
never injected the lobular biliary plexuses, to the extent represented in the cut.
It is, therefore, to be considered rather as a diagram, illustrating the structure,
in accordance with the results of his diflferenl observations and experiments.

ANATOMY OF THE LIVER.

99

of most other anatomists) is composed according to him, of a
plexus of bihary ducts, (see fig. 148,) and a plexus from the
portal vein placed on its exterior surface, (see fig. 149,) of
branches of the hepatic artery, and of a branch of an hepatic
vein, which occupies its centre, (see fig. 150.) Nerves and
absorbents, it is also probable, enter into its structure, but they
cannot be traced upon it. The plexuses formed by the hepatic
ducts in each lobule, may be called the lobular biliary, or

Fig. 149.*

secreting biliary plexuses. The ducts forming them being
exceedingly minute, and anastomosing very freely with each
other, as seen in fig. 148. At their termination, they appear

* Fig. 149, represents the interlobular branches of the portal vein, and the
lobular venous plexuses formed by the intralobular branches of the hepatic
veins, a, a. a, Interlobular portal veins contained in the spaces, b, b, b, The
interlobular portal veins of the fissures and which with the veins in the spaces,
form venous circles round the lobules. This is the appearance which the venous
circles present when examined with a common magnifying glass. They are,
however, formed by numerous, and not by single branches, as represented in
the figure, c, c, c, The lobular portal venous plexuses, the branches of which
communicating with each other by intermediate vessels, terminate in the intra-
lobular veijis. The circular and ovoid spaces seen between the branches of the
plexuses, are occupied by portions of the biliary plexuses, constituting the acini
of Malpighi. d, d, d, The intralobular branches of the hepatic veins, in which
the vessels of the plexuses terminate. — p.

100

KIERNAN ON THE MINUTE

Fi^. 150 *

to have no communication with the veins, and hence it is dif5«
cult to inject these plexuses with mercury or size, since they
generally contain bile that has no place of escape, and which
prevents the injecting fluid in ordinary cases from filling

minutely the lobular plexuses. The
minute space between these anasto-
■_:.- ^ mosing ducts, he considers identical
with the acini of IMalpighi, which
this anatomist has but obscurely
described ; and which, moreover when
examined through the microscope,
have likewise the appearance of the cells delineated by Mascagni.
The lining membrane of the hepatic ducts, like other mucous
membranes, possesses many mucous follicles, as seen in fig.
Fig. 151f. 151. They are here arranged in rows, and from
them is derived all the mucus that is admixed
with the bile. In each lobule, the portal veins
ramify, as seen in fig. 149, among the branches
of the biliary plexus, and finally terminate near
the centre of each lobule in the hepatic veins.
The hepatic veins are very peculiar. A branch
arises from the centre of each lobule, as seen
in fig. 152 ; and each intralobular branch divides
into several capillary filaments, to receive the
blood of the portal branches, so that each lobule seems to be
placed upon one of the branches of the hepatic veins, as a leaf
upon its central stem.

— Each of these branches opens by a minute orifice, directly into
one of the divisions of the venae cavae hepaticse, this system of
veins having no cellular sheath or capsule surrounding it, as is
the case with the vena porta, but is directly in contact, through-
out its whole course in the liver with the bases of the lobules.

* 150, a, A transverse section of a lobule, b, The divided central intralobular
vein, c, The small veins, terminating in a central vein. —

t Fig. 151, represents the internal surface of a small hepatic duct, with its
follicles arranged in two longitudinal lines.

STRUCTURE OF THE LIVER.

101

Fig. 152.* The hepatic arteries, distribute

,-^ their branches in the coats of the
hepatic ducts, venae portarum
and hepatic veins ; and the veins
in which these arterial capil-
^ laries terminate, always consist,
according to Mr. Kiernan, of
the radical branches of the vena
portarum. Thus, the hepatic
arteries and the portal branches,
form the vasa vasorum of all
the different vessels and ducts of the liver ; and all the blood of
the hepatic arteries, passes first into the portal system and
thence into the hepatic veins, in its circulation through the liver.
For these reasons, Mr. Kiernan believes the bile to be secreted
solely from the blood of the portal veins. For even in the well
known case mentioned by Mr. Abernethy, where the vena porta
terminated in the vena cava without passing through the liver,
he found the hepatic arteries much larger than usual, and the
portal branches into which they terminated in their course
through the liver of corresponding development; so that
even in anomalous cases of that description, the biliary secre-
tion is made not from arterial blood, but from that of the portal
veins. The capsule of Glisson is a cellular sheath which extends
around the hepatic artery, vein and duct, accompanying their
minutest ramifications up to the lobules, and terminates by-
forming a delicate capsular investment to each of the individual
lobules. It serves, according to Kiernan, like the pia mater of
the brain, as a nidus or bed in which the larger branches of
the vessels may subdivide before entering into the delicate
structure of the lobules. In the interlobular spaces, filled up
with this tissue, the portal veins form a sort of vascular circle
as seen in fig. 148.

* Fig. 152, A, An hepatic vein. B, Lobules arranged around the intralobular
branches of the hepatic veins, as they are frequently seen at the posterior part
of the concave surface of the liver. This arrangement is more distinctly seen
in the liver of the sheep than in the human liver. These lobules are parallel to
the surface.

9*

102 HEPATIC DUCT.

— It has been asserted by Ferrein, Autenreith, Andral and
others, that there are two substances in the liver, a cortical
and medullary, or red and yellow ; the former of which was
exterior and the latter central, in each lobule. This has been
denied by Cruveilhier and Miiller; and Kiernan has shown
that this difference in color, depends upon the separate con-
gestion of one of the different system of vessels, for such is the
great vascularity of the liver that it is usual after death to find
one or other in a state of congestion. By injecting with moder-
ate force a colored fluid into the hepatic veins, he found he could
color red, even in the healthiest liver, the central parts of the
lobules ; by using more force he could color the whole substance
of the lobule, in consequence of the fluid passing then into the
portal branches. By injecting the portal system in a similar
manner, the outer part of the lobule was the first colored. The
yellow color of these acini or lobules is owing, according to
Cruveilhier, to a congestion of bile in the radicles of the biliary
ducts. The opinions of this anatomist coincide in the main in
regard to the structure of the acini, with those of Mr. Kiernan.
He believes, however, that the termination or rather origin of the
branches of the biliary duct is from the centre of each acinus,
and that immediately around this is a vascular circle formed
by the radicles of the hepatic intralobular vein, while the portal
system forms a circle extrinsic to the whole. He also believes
that there is a part of the outer surface of each lobule, which
is uninjectable, spongy and porous, and serves the part of a
filter.*—

The Biliary or Hepatic Duct, is formed of very minute
vessels, which originate in the acini above described : these
unite together like veins until they form considerable branches,
which finally compose the great ramifications of the biliary
duct. This duct is very strong and firm, and on its internal
surface are the orifices of many mucous follicles or ducts. It
passes from the transverse fissure of the liver, with the hepatic
artery, as before described, and at the distance of an inch and
a half or two inches from the fissure, it unites with a duct from
* Anat. Descript. T. ii. p. 575.

^^i^i'J::^i&.

THE GALL-BLADDER. 103

the gall-bladder, which is called the Cystic Duct. This duct is
nearly equal in length to the hepatic, and after running almost
parallel to it, at length unites so as to form an acute angle with
it. The cystic duct is smaller than the hepatic, and they unite
much like two branches of an artery.

The Gall-Bladder, from which the cystic duct arises, has
the shape of a pear, with a very long neck, curved in a way to
be hereafter described. It is situated in a superficial pit or
cavity in the concave surface of the right lobe of the liver; and
its fundus, or basis, often projects a small distance beyond the
anterior edge of the viscus. Its position is such, that it extends
from before backwards, and inclines rather to the left ; of course,
therefore, when the subject lies on his back, the bottom of the
bladder is the uppermost part of it : when he lies on the left
side, it is also higher than the neck : and when he lies on the
right side it is the lowermost.

The gall-bladder consists of an internal coat, and one that is
cellular or nervous, and has somewhat of a fibrous appearance.
It is covered also partially by the peritoneum. This coat con-
nects the gall-bladder to the surface of the pit or cavity in which
it lies. The peritoneal coat of the liver is extended from the
surface of the viscus over that part of the surface of the gall-
bladder which is not in contact with it.

The internal coat has a peculiar structure, with a faint resem-
blance to that of the villous membrane. It is so arranged as to
form very fine folds, which have various directions : in some
places they make a net-work ; in others, as the neck of the
bladder, they are longitudinal. Many mucous follicles exist on
its internal surface.

The neck of the gall-bladder is suddenly bent down or curved
upon itself, and twisted, so that it resembles the neck of the
swan, when the head of that bird is applied to one side of its
breast.

A branch of the hepatic artery, which leaves it before it
enters the liver, is appropriated to the gall-bladder, and is,
therefore, denominated the cystic artery. The veins corres-
ponding to this artery empty themselves into the vena por-

104 THE GALL-BLADDER.

tarum.* The lymphatic vessels are united to those which
are found on the lower surface of the liver, and the nerves are
derived from the hepatic plexus.

The gall-bladder appears to be merely a reservoir, into
which bile passes through its duct in a retrograde direction.
If air be blown through the hepatic duct from the liver, it will
pass to the gall-bladder almost as freely as it passes to the
duodenum.

The biliary duct from the liver, after receiving the duct from
the gall-bladder, takes the name of Ductus Communis Chole-
dochus. It is wider than either of the other ducts and near
three inches in length. — It is composed of two tunics, an in-
ternal mucus and an external one. The external one, or
cellular coat as it has been called, is now generally admitted to
be made up of the contractile jihrous tissue, which is a kind
of substitute for muscular structure. In some of the lower
animals it evidently consists of muscular fibres. — It passes
down before the vena portarum, and on the right of the hepa-
tic artery, to the posterior surface of the right extremity of the
pancreas. It passes through a small portion of that gland, and
then perforates the muscular coat of the duodenum ; after which
it proceeds from half an inch to an inch between this coat and
the villous, and opens into the cavity of the intestine. The
orifice forms a tubercle which extends lengthwise of the intes-
tine, and is rounded above and pointed below, with a slit in it.
While this duct is in contact with the pancreas, a duct from that
gland generally opens into it, so that the biliary and pancreatic
fluids enter the duodenum by the same orifice ; but sometimes
the pancreatic duct opens into the duodenum, by a distinct
orifice, very near to that of the biliary duct.

The Bile, or fluid secreted by the liver, appears to answer a twofold purpose in
the animal economy. It produces a chemical efTect upon the alimentary
mixture which passes from the stomach through the intestines ; and it
increases the peristaltic motion of those important organs.

By an inverted action of the duodenum, some of this fluid is frequently carried

* It has been justly observed by John Bell, that the veins would not terminate thus, ir
bile were secreted by the gall-bladder.

THE PANCREAS. 105

upwards into the stomach : it then often produces only slight derangement of
the functions and sensations connected with that viscus; but sometimes vio-
lent vertigo, and even convulsions, seem to have arisen merely from the presence
of a large quantity of bile in the stomach : for they have gone off completely
upon the discharge of bile by vomiting.

Notwithstanding these effects of bile in certain cases, in which a great deal of
it exists in the stomach, it is often carried into the mass of blood in large
quantities, and appears to be mixed with the serum, and to circulate through
the body, without producing any very sensible effect : thus many persons
who are deeply tinged by bile in their blood, experience but few effects that
can be imputed to the mixture of it with the circulating fluids : and neither
the brain nor the heart appears to be much influenced by the circumstance.

Bile is miscible with water and with alcohol, and also with oily substances ;
and it often assumes a green color, when mixed with acids. The color of
the alvine discharges is derived from the bile, and they are therefore some-
times very green, when the acetous fermentation takes place in the contents
of the stomach and bowels.

It is asserted by some chemists, that ten parts in eleven of the human bile
consist of water; that albuminous matter composes about one- forty-sixth
part of it ; and that there is nearly an equal quantity of resinous matter in it.
There is also a small quantity, (one part in 244,) of uncombined soda dis-
solved in it, and a small quantity of neutral salts, consisting of soda combined
with the phosphoric, sulphuric and muriatic acids. In addition to these is a
very small quantity of phosphate of lime and of oxide of iron, and some
yellow insoluble matter.

The bile in the Gall- Bladder is generally more viscid than that which is found
in the Hepatic Duct.

Of the Pancreas.

The pancreas is a glandular body, which has a strong resem-
blance to the salivary glands in several particulars. It is seven
inches in length, and is irregularly oblong in its form, one ex-
tremity being much longer than the other. Its large extremity
is in contact with the duodenum, and it extends from this in-
testine in a transverse direction to the spleen, to which it is
connected by the omentum and by blood-vessels. It is not
invested by the peritoneum, but is situated in the space which
exists between the two lamina of the mesocolon, as they
proceed from the back of the abdomen, before they come in
contact with each other. It is anterior to the aorta and vena
cava, and to the mesenteric vein, or main branch of the vena
portarum ; being connected to these parts by cellular mem-
brane. At the right extremity, which is connected with the
duodenum, is a process of the gland that extends downwards

106 PANCREATIC DUCT.

in close contact with the intestine. This is called the head of
the pancreas, or the lesser pancreas.

The position of the pancreas is such, that one of its surfaces
looks forwards and rather upwards, and the other backwards
and downwards ; one edge is of course posterior and superior,
and the other interior and inferior. The posterior of these edges
is much thicker than the other, and has a groove or excavation
which is occupied by the splenic blood-vessels.

This gland differs from the other large glands of the abdo-
men, inasmuch as it has not a large artery particularly appro-
priated to it ; but instead of this, it receives branches from the
contiguous arteries.

The arterial blood of this gland is partly supplied by the
splenic artery, which, in its course from the main trunk of the
coeliac to the spleen, while it is in the groove at the edge of the
pancreas, sends off into the gland one considerable branch
called the great pancreatic, and a number of small branches,
which go off in succession. In addition to these, the pancreas
receives vessels from one of the branches of the hepatic artery,
before it sends off its great ramifications, as well as small twigs
from several other contiguous arteries. The veins correspond
with the arteries, but ultimately are discharged into the vena
portarum.

The pancreas resembles the salivary glands in color, and
also in texture ; for it is of a dull white color with a tinge of
red, and it appears to consist of small bodies of a granulated
form, which are so arranged as to compose small masses or
lobes that are united to each other by cellular membrane.
Each of these granulated bodies receives one or more small
arterial twigs, and from it proceeds not only a vein but a small
excretory duct, which, uniting with similar ducts from the ad-
joining granulated portions or acini, forms a larger duct in each
lobe or mass ; these open into the great duct of the gland, which
proceeds through it lengthwise from the left extremity, in which
it commences, to the right.

This duct is situated in the body of the gland, which must
be dissected to bring it into view. It is thin and transparent,

THE SPLEEN. 107

like the ducts of the salivary glands, and is rather larger in
diameter than a crow's quill. In its progress towards the right
extremity of the gland, it gradually enlarges, and commonly
receives a branch from the part called the lesser pancreas. It
most commonly unites with the biliary duct before it opens
into the duodenum : sometimes these ducts open separately, but
very near to each other. They penetrate the coats of the in-
testine, rather obliquely, and between four and five inches from
the pylorus, see fig. 135, p. 32. This canal is sometimes called
Ductus Virsungii, after an anatomist who published a plate
of it.

The pancreas has an irregular surface, and no coat which
covers it uniformly. It is invested by cellular membrane, which
also connects its different lobes to each other. Absorbent ves-
sels and nerves are traced into it.

The portion called the lesser pancreas adheres to the duode-
num, and when it is enlarged by disease, the passage of aliment
through that intestine is much impeded, and sometimes com-
pletely obstructed.*

It is now generally believed that the fluid secreted by the
pancreas is nearly similar to that which is produced by the sali-
vary glands. •

Size oj the Spleen.

The spleen is a flat body of a bluish color, and an irregular
oblong form, with thick edges, which are indented in some
places.

It is various in different subjects, both in size and form. Its
most common size is between four and five inches in length,
and about three or four inches in breadth ; but it has often
been found of more than four times this size ; and it has also
been seen not much longer than an inch. Its ordinary weight
is between six and nine ounces ] but it has varied in different

* In several cases where examination after death evinced that the pancreas
had become enlarged and indurated, particularly at the right extremity, the
principal symptoms were jaundice ; great uneasiness after taking food ; vomiting
some time after eating, but not immediately ; and extreme acidity of the matter
rejected.

108 THE SPLEEN.

subjects from eleven pounds to one ounce. It is supposed, by
many physiologists, that it frequently varies in size in the same
individual.

It is situated in the left hypochondriac region, in contact
whh the diaphragm, below the eighth rib. The position of
the spleen is somewhat oblique, — one extremity being directed
downwards and rather forwards, and the other upwards and
backwards ; but when the stomach is distended, the lower
end of it is pushed forward by the great extremity of that
viscus.

In general it is so deeply seated in the left hypochondriac
region, that it is out of view when the subject is opened in the
ordinary way : but in some cases of enlargement, after the inter-
mitting fever, it has extended downwards, nearly as low as the
pelvis ; and towards the right side beyond the umbilicus.

The external surface of the spleen is convex, in conformity to
the surface of the diaphragm, with which it is in contact. The
internal surface of the spleen is irregularly concave, having a
longitudinal fissure which divides it into two portions.

The spleen is invested by the peritoneum, one process of
which is often extended from the diaphragm, above and behind
it, in the form of ligament. Another process of the same mem-
brane is extended to it from the great extremity of the stomach.
The peritoneum is also continued from the spleen in the form of
omentum, (gasti-o-splenic.)

Within this peritoneal covering is the proper coat of the
spleen, which is so closely connected to it, that many anatomists
have considered them as one membrane : they are, however,
very distinct at the great fissure, but the external coat is ex-
tremely thin.

The proper coat of the spleen is not very thick ; it is dense
and firm, and somewhat elastic, but not much so. It is partly
transparent.

The spleen has a large artery, which is one of the three
great branches of the coeliac. This vessel runs in an undulat-
ing manner in a groove in the upper edge of the pancreas, and
in this course sends off many small branches to supply that

;'.^',vr:^>i>A',.,..a^4.^i-

VESSELS OF THE SPLEEN. 109

gland. The splenic artery, before it arrives at the spleen,
divides into five or six branches, which are also undulating in
their progress, and penetrate into the body of the viscus at the
above mentioned fissure. These branches are distributed to
every part of the viscus, and ramify minutely.

From these branches, or from the main trunk before it rami-
fies, three or four smaller branches proceed to the left extre-
mity of the stomach. They are called vasa brevia or arterise
breves.

The arteries which enter the spleen are accompanied by
veins that emerge from it, and unite to form a great trunk.
This trunk observes a course corresponding to that of the
splenic artery, and receives veins from the stomach and pan-
creas, which correspond with the arterial branches sent to those
organs. The splenic vein is one of the principal branches of the
vena portarum.

The splenic artery is very large in proportion to the viscus
to which it is sent, and the vein is unusually large in proportion
to the artery. The vein is also very tender and delicate in its
structure.

The absorbent vessels of the spleen are very numerous. It
has been asserted, that when those of the external coat of the
spleen are injected, they are sufficient to form a fine net-work
on it. The absorbents of the deep-seated parts unite to the
superficial at the fissure where the blood-vessels enter. They
terminate in the thoracic duct, after passing through several
lymphatic glands.

The nerves of the spleen are derived from the solar plexus :
they form a plexus around the vessels, and accompany them
through the viscus.

The spleen consists of a substance which is much softer than
that of any other viscus of the abdomen. This substance is
made up either wholly or in great part of the ramifications of
the splenic artery and vein, which are demonstrated by injec-
tions to be very minute and numerous in this body. There are
also many fine white cords, like threads, which pass from the
internal surface x)f the inner coat of the spleen in its soft sub-

VOL. II. 10

110 MALPIGHI ON THE STRUCTURE OF THE SPLEEN.

Stance, in which some of them ramify. These cords connect the
substance of the spleen pretty firmly to its coat, and they seem
to have the effect of rendering the exterior part of the substance
more firm and dense than the internal. They are particularly
conspicuous if the spleen be immersed in water, and the coat
pulled off while it is in that situation. — The proper or elastic
coat of the spleen, besides sending inwards the cords above men-
tioned, gives off tubular processes which serve as sheaths or
investments to the vessels which enter it. —

The spleen has a strong resemblance to the glandular organs
hut has no excretory duct, and its particular function is not
very obvious : for these reasons the structure of this organ is a
subject of very interesting inquiry.

Malpighi, who took the lead in researches of this nature,
before injections of the blood-vessels with wax were in use,
after investigating the structure of the spleen by long macera-
tion, by boiling, by inflation, by the injection of ink or colored
fluids, and by examination with microscopes, declared that its
structure was cellular; that the cells communicated more freely
with the veins than the arteries ; and that they might be con-
sidered as appendices of the veins. He also asserted, that a
large number of white bodies or vesicles were to be found in
those cells and throughout the whole substance of the spleen,
which were in bunches like grapes, and preserved their whitish
color although the vessels around them were injected with a
colored fluid. This description of Malpighi appears to have
been admitted by some of the very respectable anatomists who
were contemporary with him; but it was zealously opposed by
Ruysch, who exhibited the spleen so completely injected with
wax, that it appeared to be composed entirely of vessels.*

Ruysch appears to have paid great attention to this subject,
and to have made many preparations of the spleen. From
these he derived the opinion, that the substance of this organ
was entirely composed of arteries, veins, absorbent vessels and

* Two plates, taken from drawings of these preparations are published in
Ruysch's Works. One is attached to Epistola Problematica Quarta, in the
second volume ; and the other in Thesaurus Septimus, in tfie third volume.

RUrSCH AND DE LA SONE ON THE SPLEEN. Ill

nerves ; and that if it were properly injected before It was dis-
sected, no other structure would be found. He stated, that the
minute ramifications of the blood-vessels appeared to have
acquired a peculiar quality, and were so soft and delicate that
their texture was destroyed by the least friction ; and that by
the slightest degree of putrefaction they appeared to be reduced
to a fluid state. He also denied the existence of cells, or of the
whitish bodies described by Malpighi.

The question thus at issue between these great masters of
their art was very carefully examined by M. De La Sone, a
French Physician, whose observations are published in the
Memoirs of the Academy of Sciences for 1754. After repeating
the processes of each of these anatomists, and instituting some
others in addition, he adopted the opinion that there was in the
texture of the spleen, a pulpy substance which was not a mere
coagulum, but which, however, could not be injected.

He derived this opinion from this fact among others. After
macerating the spleen a considerable time, and injecting water
into the vessels until it returned colorless, he injected ink, and
confined it some time in the vessels by tying them : he then
allowed the ink to flow out of the vessels, and made various
sections of the spleen ; but no ink appeared in the pulpy sub-
stance, although it was visible in small vessels which ramined in
that substance. He observed that this could not have been the
case, if the pulpy substance had been composed entirely of ves-
sels, as was supposed by Ruysch.

He also examined the spleen after it had been injected with
wax, according to the manner of Ruysch, and believed not only
that the pulpy matter remained uninjected, but that Ruysch
himself, in his own preparation, removed this substance, suppos-
ing it to exist for the mere purpose of connecting the vessels to
each other.

To see the blood-vessels in the same state of distention
in which they were during life, he tied the splenic vessels in a
living animal, and removed the spleen with the ligatures on
the vessels. In this situation he boiled it, and then examined
the appearance of the vessels and the pulpy substance. — From

112 HALLER AND THE FRENCH ANATOMISTS ON THE SPLEEN.

these, as well as his other observations, he decided, that
the pulpy substance did not consist entirely of vessels, but was
an additional and different structure.

He also suggested, that as the brain and muscular fibres were
so covered by blood-vessels in the injected preparations of
Ruysch, that they appeared to be composed entirely of vessels,
when in fact they consisted of a different substance, so the
pulpy substance of the spleen was covered or obscured by the
blood-vessels which passed through it, without constituting its
whole substance.

He confirms the account of Malpighi respecting the Whitish
Vesicles or Follicles, and states, that in a majority of cases they
are not to be discovered without a particular preparation ; but
that they are generally made obvious by long maceration of the
spleen in water. In his opinion they are the most essential part
of the organ.

Notwithstanding these investigations of M. De La Sone, the
question respecting the structure of the spleen remains not com-
pletely decided even to this day.

Haller, who was perfectly well acquainted with the subject,
inclined to the opinion of Ruysch ; while Sabatier adopted
completely the opinion of De La Sone.

It appears from the statement of Gavard, that Desault did not
admit the existence of the transparent bodies ; although he
believed that the pulpy substance of the spleen consisted
of cells which resembled those of the cavernous bodies of the
penis.

Boyer, whose descriptions of the animal structure appear to
have been formed with scrupulous exactitude, admits the exist-
ence of transparent bodies ; sometimes so small' as to be scarcely
visible, and sometimes as large as the head of a pin. He
observes, that the best method of examining them is to place a
very thin slice of the spleen between the eye and a strong light,
when the transparency of these bodies occasions the slice of the
spleen to appear as if perforated.

As to the general structure of the pulpy substance, he avows
himself unable to decide respecting it ; but observes that upon

BRITISH ANATOMISTS ON THE SPLEEN. 113

examining the cut surface of the spleen, you perceive black
liquid blood flow from the vessels ; if you then scrape this sur-
face, you may express easily a species of sanies different from
that which flows from the vessels, which, after exposure, be-
comes red, and resembles coagulated Wood ; whether this is con-
tained in the capillary vessels, or in the cavties of this organ,
he acknowledges himself unaWe to determine.

Notwithstanding the sendments of these French gentlemen,
many of the British anatomists, who are entitled to great atten-
tion on account of their skill in minute injections, have adopted
the ideas of Ruysch. Among these are to be mentioned the
late Dr. F. Nicholls. and many of the anatomists of London,
as well a? the second Professor Monro, of Edinburgh. There
are, however, two remarkable exceptions to this account of the
British anatomists. The late Mr. Falconer, who wrote a dis-
sertation on the situation and structure of the spleen, which
contains the sentiments of the late truly respectable Mr. Hew-
son,* after stating that the organ was extremely vascular, so
that when injected it appeared like a mere congeries of vessels,
makes this unequivocal assertion — that there are innumerable
cells dispersed throughout the whole substance of it, which are
so small that they are only to be discovered by the aid of a
microscope ; and are to be seen after steeping a thin piece of
spleen, the blood-vessels of which have been minutely injected,
in clear water during a day, and changing the water frequently.
He also adds, that the ultimate branches of the arteries and
veins form a beautiful net-work on each cell ; and that these
cells are sufficiently distinguished from the irregular interstices
of the cellular substance, by their round figure and their great
regularity.

Sir Everard Home, in his papers on the structure and uses
of the spleen, confirms the account of the vesicles in this organ ;
and adds that these vesicles are occasionally seen in a distended
and in a contracted state. That when distended they are twice
as large as when contracted, and are distinguishable by the

♦ See Experimental Inquiries, vol. iii.
10*

114 THE STRUCTURE OF THE SPLEEN.

naked eye ; whereas when contracted, they require a magnifying
glass to be distinctly seen. These observations appear to have
been made upon quadrupeds.*

Professor Soemmering appears to unite in the general senti-
ment of the British anatomists, that the spleen is simply vascu-
lar. He says, that the tuberculi which sometimes appear in it,
when examined with a magnifying glass, appear to be composed
entirely of vessels.

There are, therefore, two questions not perfectly decided
respecting the spleen.

First. Whether its general structure is simply vascular ; or
whether there is any other structure either cellular or more sub-
stantial, which composes its general bulk.

Second. Whether the small transparent vesicles, originally
described by Malpighi are to be regarded as essential parts of
the structure of the spleen.

With respect to the first question, the injections of Ruysch,
and of the British anatomists in general, and even of Mr. Hew-
son, as well as of Haller and Soemmering, seem to afford posi-
tive facts in opposition to those of a negative kind adduced by
M. De La Sone, and render it highly probable that the general
structure is simply vascular.

But the second question stands on different grounds. The
existence of small transparent vesicles, although denied by
Ruysch, and neglected by the British anatomists in general,
was asserted as d. positive fact by Malpighi and De La Sone ;
and their assertions have been confirmed, not only by most of
the French anatomists, but also by Hewson and Home among
the British.

The sentiments of physiologists respecting the functions of
the spleen, are more discordant than those of anatomists respect-
ing its structure ; although the subject has been considered by
many authors of great ingenuity .f

* See the London Philosophical Transactions for 1808.

t See M. Lieutaud, Elementa Physiologise ; Hewson's Experimental Inquiries,
vol. iii. ; Dr. Rush, Medical Museum, vol. iii. ; and Haller, Elementa Physi-
ologiae, torn. vi. page 414.

THE STRUCTURE OF THE SPLEEN. 115

-^The spleen is met with only in vertebrate animals, and in
them its presence is nearly constant. The whitish rounded
corpuscles of Malpighi, which are found in many animals and
occasionally in man, and are visible to the naked eye in the red
substance of the spleen, were described by Dupuytren and
Assolant as greyish bodies, without any cavity in their interior, one-
fifth of a line in diameter, and so soft as to take the liquid form
when raised on the knife. More recent observations have shown
them to be vesicles, and not solid bodies containing an albumin-
ous fluid. They appear to be appended in groups of six or
eight to an arterial ramuscule.

— Miiller considers them as growths or processes connected
with the sheaths with which the capillary branches of the
splenic artery are provided. Of their intimate texture and uses
nothing is positively known. They are supposed to belong to
the absorbent system and to consist of dilatations of the absorb-
ent vessels.

— The pulpy substance of the spleen consists of a mass of red-
brown granules, as large as the red particles of the blood, but
differing from them in form, being very irregularly globular.
— These granules are easily separable from each other, and in
their midst the minute arteries ramify in tufts, and terminate in
the plexus of venous canals, in which all the blood of the spleen
is poured, before it is carried out of the organ by the splenic
vein. There are no distinct cells in the spleen ; those spaces
seen in sections of the organs which have been mistaken for
cells, are divided venous canals exceedingly thin and delicate.
When the spleen is inflated with air, these vessels are distended
and assume a slightly cellular appearance.

— The spleen is now generally considered as belonging to the
class of erectile or distensible tissues, and to serve as a diver-
ticulum or temporary outlet to the blood, which accumulates
in the venous plexuses of the stomach during digestion, and also
when the blood is hurried so rapidly through the system as in
running, as to endanger some of the weaker vessels ; in the latter
case the accumulation is usually attended, especially in young
persons, with pain in the region of the spleen. Its uses in the

116 EXTIRPATION OF THE SPLEEN.

economy are by no means well understood, and in health or
disease, it seems to have but little functional connexion with
other organs. In the female, it appears to sympathize more
with the organs of generation than any others. Its extirpation
in animals may take place without destroying life. This ope-
ration was practised by Dr. Schultz,* twenty-seven times in
dogs, cats, goats, and rabbits, and of which but one died from
the experiment. When the wound had healed, he remarked but
little functional disturbance in any of the organs of the body
except the generative. The chyle drawn from the thoracic
duct, presented the same appearance as that of animals in which
the experiment had not been practised ; a result not in accord-
ance with the opinion of Tiedemann and Gmelin, who affirm
the use of the spleen to be that of furnishing through its numer-
ous absorbent vessels, a fluid which reddens and assists in
animalizing the thoracic chyle.

— In the animals operated upon, the power of procreation was
greatly impaired, though not entirely destroyed.

* Hecker's Annalen, torn. xii.

THE GLANDULE RENALES. 117

CHAPTER IV.

OF THE URINARY ORGANS AND THE GLANDULE RENALES.

The lu'inaiy organs consist of the Kidneys, which are
situated in the lumbar regions ; of the Bladder, which is in the
pelvis ; of the Ureters, which are flexible tubes or canals that
pass from the kidneys to the bladder ; and of the Urethra, or
tube through which the urine is discharged from the bladder.

These organs have but little connexion with the peritoneum.
The kidneys are behind it, and a considerable quantity of cellu-
lar membrane is placed between them and it. The ureters
are also behind it ; and but a part of the bladder is invested
with it.

The GlandulcB Renales are described with the urinary organs,
on account of their contiguity to the kidneys ; and to avoid a
derangement of the natural order of description, they are
considered first.

The urethra pertains to the organs of generation as well as to
the urinary organs, and can be described most advantageously
with them.

Of the Glandulce Renales. (Renes Succenturiati, CapsulcE
Atrabiliares.)

These are two small bodies situated on the psoas muscles, one
on each side of the spine, behind the peritoneum and above the
kidney, being in contact with its upper and anterior edge. They
have an irregular semilunar figure with three aides, one of which
is accommodated to the convexity of the kidney. Their color is
commonly a dull yellow.

The appearance and texture of these bodies have some resem-
blance to those of glands, and hence their name^ but they have
no excretory duct.

When they are laid open by an incision, a cavity often appears,

J 18 CAPSULE RENALES.

which is somewhat triangular, and from the lower part of it a
small thin ridge arises.*

A small quantity of fluid is generally found in it, which has a
very dark color in adults, is yellowish in young subjects, and red
in infants.

These bodies have not a single artery appropriated to them,
as the spleen has, but receive small branches from several
contiguous sources ; namely, from the arteries of the diaphragm,
from the coeliac artery or the aorta, and from the arteries of the
kidneys. There is generally one principal vein, as well as some
that are smaller, belonging to each of these bodies : the large
vein, on the right side, generally opens into the vena cava ; and,
on the left, into the left emulgent vein.

These bodies were first described by Eustachius, and have
been regarded with attention by many anatomists since that
period. They exist in a great number of animals ; but their
nature and functions are altogether unknown.

— Rayer,f adopts the opinion of Meckel, that in the normal
state there is no cavity whatever in the renal capsules. When-
ever I have observed this cavity in my dissections, it has been
always filled with dark blood or a yellowish albuminous fluid,
and the walls of the cavity have presented an irregular appear-
ance, though having the general triangular form of the gland.
In the healthy state, the supra renal vein can be traced into the
centre of the gland which then presents a spongy appearance.
The vein itself is dilated so as to form a sort of sinus in the
interior of the gland.

— Rayer considers the cavity as always produced by hasmorr-
hage arising from a rupture of some of the lax vessels of the
capsule, which causes a forcible separation of the soft tissue of
the gland. He describes several cases of what he calls apoplexy
of the gland, where a large amount of blood was collected
in a cyst formed from the gland. Miiller believes that the deve-
lopment of these glands is in some measure connected with
that of the generative organs.

* The cavity in these bodies has sometimes been sought for in vain. Haller
found it in sixteen cases out of nineteen,
t Sur les Maladies des Reins. — p.

THE KIDNEYS AND URETERS. 119

-In structure they are. composed of two different looking
substances which have been called cortical and medullary.
The first is yellowish and external, and appears to be striated
perpendicularly to its surface, from the direction in which the
capillaries run through it. The medullary is in the centre, and
is brown colored and soft. —

Of the Kidneys and Ureters,

The kidneys are two glandular bodies which secrete the
urine. They are of a dull red color, and their form has a
strong resemblance to that of the bean which bears their
name. They have a peculiar texture, which is uniform, and
not granulated or composed of acini ; and they are covered
by a thin delicate fibrous tunic, which has no connection with the
peritoneum.

They are situated in the lumbar regions of the abdomen, one
on each side of the spine. They are opposite to the two last
dorsal and the two first lumbar vertebrae. They rest principally
upon the psoas and quadratus lumborum muscles, and their
position is oblique ; the concave edge presenting inwards and
forwards, the convex edge backwards, and the upper extremity
approaching nearer to the spine than the lower.

The Right Kidney is situated rather lower than the left :
it is below the posterior part of the right lobe of the liver, and
behind the duodenum and the colon. The Left Kidney is
below the spleen, and behind the descending portion of the
colon. Each of the kidneys is below and very near to one of
the glandulae renales.

They are surrounded with a large quantity of lax adipose
membrane, which in corpulent persons forms a very large mass
of adeps around them ; while in the emaciated they are sur-
rounded with a membrane almost free from fat. Each kidney
has two broad sides, two extremities, and two edges. The side
or surface which is posterior, when the kidney is in its natural
situation, is rather broader than the other. The upper extre-
mity, or portion, is also broader and larger than the lower. The
edge which is posterior and external is regularly convex ; the
anterior edge is concave ; but the concave edge or margin is

120 THE KIDNEYS.

not very regular. In the middle it is. largely indented ; in this
indentation is a deep fissure, which separates the two broad sur-
faces or sides of the gland from each other ; and here the breadth
of the posterior surface is evidently greater than the anterior.

Each of the kidneys receives a large artery, which proceeds
immediately from the aorta, nearly in a rectangular direction.
A vein, which opens into the vena cava, accompanies the
artery. It is obvious, from the situation of the kidneys with
respect to the great vessels, that the artery on the right side
must be longer than that on the left, and that the reverse of
this must be the case with the veins ; the veins are also anterior
to the arteries. At the great fissure these vessels divide into
several branches, which enter the kidney at that place. The
branches of the vein are before and above ; those of the artery
are below, and in the middle. Surrounded more or less by the
branches of those vessels, is a membranous sac ; the breadth of
which extends from above downwards. This sac terminates
in a tube that proceeds from the lower part of the fissure down
to the bladder. The sac is denominated the pelvis of the kid-
ney, and the tube a ureter: each of these parts will soon be
more particularly described.

The substance of the kidney, as has been already said, is
uniform in its texture, and of a reddish brown color. When
it is divided by an incision made lengthways, and from its
convex to its concave edge, there appears to be a small differ-
ence in the different parts of it. The exterior part, which is
called cortical, is rather more pale in color and softer in
consistence than the internal part. It varies in thickness, so
that some writers have described it as equal to two lines, and
others to one-third of the kidney. In a majority of subjects it
will be found between the two statements.

The interior part is called medullary, or tubular, and appears
to be composed of very fine tubes. These tubes are so
arranged, that a number of papillae or cones are formed by
their convergence, and project into the fissure of the kidney.
These papillae have been supposed to consist of a substance dif-
ferent from either of the two above mentioned, but they appear
to be formed merely by the tubular part.

i^2sfadii^(^dkM)i^

THE KIDNEYS. 121

The arteries, accompanied by corresponding veins, and by-
nerves and absorbent vessels, after ramifying in the fissure of the
kidney, proceed into its substance, and continue their arborescent
ramifications until they have arrived very near the exterior sur-
face. They are so uniformly distributed to the different parts of
the organ, that when the blood-vessels are injected with wax,
and the substance of the kidney is removed from the injected
matter, as is the case in corroded preparations, the injection
exhibits accurately the form of the kidney.

The large branches of the blood-vessels occupy the vacuities
between the papillae in the fissure of the kidney. When they
penetrate the substance of the kidney, they are enclosed by
sheaths which are derived from the coat of the gland, and are
surrounded by membrane which frequently contains adeps.

There are commonly ten or twelve papillae in the fissure of
each kidney, but there are sometimes more and sometimes less
than this number. These papillae are surrounded by a mem-
branous sac of a corresponding form ; the papillae being a cone,
and the sac resembling the upper part of a funnel. The sac is
therefore called an infundibulum. Sometimes there are two
papillae in each infundibulum, and then the form of the sac is
not so regular. The infundibulum adheres to the base of the
papillae, but lies loose about the other parts of it. Each infun-
dibulum communicates at its apex with the pelvis of the kidney.

The Pelvis, as has been already mentioned, is a membranous
sac which terminates in the ureter, exterior to the kidney.
This sac generally divides itself, in the fissure of the kidney,
into three large irregular branches, called calices, above described,
each of which very soon terminates in three or four of the
infundibula.* That portion of the sac which terminates in the
ureter is exterior to the kidney.

When the interior parts of the kidney are exposed to view,
by the section above mentioned after the arteries and veins
have been minutely injected, the cortical part will be found to

* It is more usual now with anatomists to apply the term cmIt/x, to the cup-
like portion of mucous membrane which surrounds the papilla, and that of in-
fundibulum, to the three outlets by which the ten or twelve calices discharge
into the common cavity of the pelvis of the kidney. — p.

VOL. II. 11

122 CORTICAL AND TUBULAR PORTIONS OF THE KIDNEY.

consist almost entirely of the minute ramifications of these
vessels. Among them are some small bodies, which are dis-
persed through the substance, Hke berries on a bush : these are
asserted also to be composed of vessels.

The tubular part certainly proceeds from this vascular
cortical substance: for Ruysch, and after him several other
injectors, have filled these tubes with injections thrown iuto the
arteries.

The tubuli, of which this part is composed, seem to arise
obscurely from the cortical part. They soon assume somewhat
of a radiated direction, and are finally arranged so as to form the
papillae or cones above described.

On these papillse or cones some of them can be traced, uniting
with each other, to form larger tubes, which terminate on the
surfaces of the papillae, in orifices large enough to be seen dis-
tinctly. From these orifices urine may be forced out by com-
pressing the papillae. On this account the tubes have been
called tubuli uriniferi.

— The minute round bodies (glomeruli) which are distributed
like berries on a bush, among the arteries and veins of the
cortical portion, and are visible to the naked eye, are called the
corpuscles or acini of Malpighi. These bodies, Malpighi and
Schumlansky, believed to be hollow sacs, with vessels ramifying
on the parietes, and which secreted the urine. Ruysch, Hewson,
and more recently Huschke, and Miiller, have shown that they
are formed entirely of an agglomeration of minute vascular
branches appended to the minute twigs of the arteries, and are
mere reservoirs of blood. They vary from the j',^ to the ji,^ part
of an inch in diameter.

According to Mr. Bowman* the tuft of capillary vessels of
which each glomerule or Malpighian body is composed, is
enclosed within the commencing extremity of each uriniferous
tube so that the number of these bodies corresponds with
the number of uriniferous tubes. By this arrangement the
tuft of vessels is received in a sort of funnel shaped dilata-
tion of the tube as shown in fig. 153. From the interior of
the vascular glomerule, a vein proceeds smaller than the artery

* London Philosophical Transactions for 1842.

' "?'■ ■>' „ .vLn i Ml-iJMiki

DUCTS OF FERREIN. DUCTS OF BELLINI.

123

^^'

which uniting with the veins form other Fig. 153.

glomerules contributes to the formation of
the dehcate venous plexus, wliich sur-
rounds the tortuous uriniferous tubes in the
conical part of the kidney.
— The colloidal, medullary or tubular
portions of the kidney, are from twelve
to eighteen in number. The bases of these
are rounded, and turned to the cortical
matter which covers them to the thickness
of two lines, and dips in for a much
greater depth between their rounded margins. The arteries
and veins send up their ramifications to the cortical mat-
ter, between these different conoidal bodies so as to separate
them from each other. The conoidal bodies terminate in the
caliceSj'in little nipple-like projections, called papilla renales.
At the apex of these, there is usually a depression, called
foveola. There are usually but ten or twelve of these papillas,
two of the conoidal bodies terminating as before described in several
places in a common papilla. Theconoidal bodies being pyrami-
dal in their shape, are sometimes called the pyramids of Malpighi.
— Each of these conoidal bodies or pyramids, is composed of an
immense number of minute tubes, {tuhuli uriniferi,^ which termi-
nate by a small number of orifices on the surface of its papilla.
— The tubes originate in the cortical portion, in their course
through which they are serpentine and tortuous, and are called
the ducts of Ferrein (dacti Ferreinei ;) the same ducts, as
they pass from the cortical matter to the papilla become straight,
and are called the ducts of Bellini, from two anatomists who
devoted much attention to the structure of the kidney. Ferrein
ascertained that the o-eneral convergence , of each cone or

* Plan of the venal circulation after Mr. Bowman, a, Branch of the venal
artery givingoff twigs to the raalpighian bodies. 1, A twig sent to one of these
bodies or gloraercules(?n). From the glomercule {m) the uriniferous tube is .seen
taking its tortuous course to {t), after which it becomes straight. 2, 2, Various
efferent veins forming a plexus (p, p.) about the tubuli urinileri. This venous
plexus transmits its blood, by a larger branch (f) which runs between the pyra-
mids and by the side of the arterial branches, to empty into the great venal
vein. —

124 STRUCTURE OF THE KIDNEY.

pyramid of Malpigbi, from Its base to its papilla, was caused
by the union of many of the ducts together, into common tubes,
so as to constitute lesser pyramids, called the pyramids of
Ferrein, (Pyramides Ferreinei.) The ducts of each of these
pyramids, subsequently unite together, so that the conver-
gence is uniform down to the papilla, where for the whole of
the tubes of each conoidal body, there appears to be but from
twenty to thirty terminal orifices. In each conoidal body, the
pyramids of Ferrein, are said by that anatomist to be seven
hundred in number, which, as the number of cones in a kidney
are upon an average about fifteen, would make the whole
number ef pyramids in the kidney, ten thousand five hundred.
— Again, each of the pyramids of Ferrein, is said at its base to
be composed of many hundred separate tubes, each of which
tubes, according to Eysenhardt, is composed of twenty smaller
ones : but the observations of this latter writer, even by the
German anatomists, are considered rather as an exaggeration.
— The exact mode of origin of the tubuli uriniferi has been
long a question of doubt. According to Krause and Miiller
and most modern observers who have investigated this subject,
they originate as closed tubes, like the ducts of other glands.
Mr. Bowman as before noticed, considers the closed tubes to be
expanded into pouches at their coecal ends for the purpose of
lodging the glomerules each pouch being pierced by two orifices,
for the accommodation of the entering artery and efferent vein.
These ducts, when examined with the microscope in the
cortical portion, appear two or three times less in diameter,
than the tubuli seminiferi, and therefore invisible to the naked
eye, though they are still much larger than the capillary
blood-vessels, which form in the cortical structure of the kid-
neys a very minute net-work. The ducts of the cortical
portion (ducti Ferreinei,) anastomose frequently with one
another ; they are flexuous and closely aggregated together,
which gives to the cortical matter the appearance of a solid mass.
— From the minute currents of blood with which these vessels
supply the glomerules and the walls of the ducts, the secretion
of urine, takes place ; a part of the contents of the blood-ves-
sels permeating their walls, and undergoing in the transit proba-

'.ar..>i.',4vl

NERVES AND LYMPHATICS. COAT OF THE KIDNEY.

125

biy some change. It is certain, that there is some intimate
communication between the origin of the ducts, and the
radicles of the veins, even in man and the higher animals. In
oviparous animals, as has before been observed, the secretion of
urine takes place from a portal vein.

— A fine injecting fluid will pass readily from the veins into
the uriniferous tubes ; and 1 find no difficulty in passing air in
the retrograde direction, from the ureter into the veins by infla-
tion of the former with a large blow-pipe ; the cut extremity of
the veins being retained under water, large bubbles of air will
be seen to escape from it during inflation. M. Huschke,* was
also very successful in passing colored fluids in the same
direction, by the aid of the air-pump. The uriniferous tubes
were always well injected, the fluid passing in by the orifices
on the papillae ; and in most cases the venous plexus in the
cortical structure, was also filled. But in no instance, in man
or the inferior animals, did he find the fluid passing into the cor-
puscles of Malpighi, or into the arteries.

Fig. 154.f — The average weight of a

healthy kidney in the male
according to M. Rayer is 4|
ounces ; in the female 3g. The
left kidney in both sexes is
usually larger than the right.
In the nephritis alhuminosa,
(granular disease of Bright,)
which is an affection of the
cortical or glandular substance
only, attended with albuminous
urine, the first development of
the minute red points, which
subsequently become the gran-
ulations of Bright, correspond
for the most part according to
Rayer,J to the highly vascular
corpuscles of Malpighi. —

* Isis, torn. xxi.

t Fig. 154 is a vertical section of a kidney, in which the ureter is seen en-
tering the organ, and dilating into a large sac called the pelvis. The pelvis is
11* X Oper. citat.

126 STRUCTURE OF THE URETERS.

In the foetal state the kidney is formed of a number of dis-
tinct lobuli, each of which consists of a papilla with the cortical
matter connected to its base. Soon after birth these lobuli
coalesce ; and in two or three years the substance of the kidney
appears uniform, as above described. In some animals this
lobulated structure continues during life : in them, and also in
the foetus, each lobe appears like a distinct organ. Although
in the adult kidney this structure has disappeared, the papillae
and the tubular part connected with them are somewhat detach-
ed from each other, in a manner corresponding to their original
arrangement.

— In the foetus the renal capsule appears very large, when
compared with the kidney itself; this fact seems to indicate,
that the organ performs some office of much importance in the
foetal economy. —

The JVerres of the Kidneys originate from the semilunar gang-
lion, formerly mentioned. They form a plexus round the blood-
vessels, and go with them into the gland.

The kidneys have internal and external absorbent vessels,
although the external vessels are very small. These absorbents
pass through glands in the lumbar region to the thoracic duct.

The proper coat of the kidney is said, by some anatomists,
to consist of two lamina ; but this cannot be shown in common
cases. It appears simple in its structure, and very flexible.
It is but slightly connected to the glandular substance which it
encloses, and may be easily peeled off. It is reflected inwards
at the fissure of the kidney, and can be traced inwardly to some
distance, forming sheaths for the vessels. In this internal
situation it is very thin.

The Ureters.
The pelvis of the kidney terminates exteriorly in the Ureter,

divided into three infundibuli, which are seen in part, in this section ; each in-
fundibulum is subdivided usually into four calices, of which, of course part
only can be seen in this section of the organ. The striated conoidal bodies are
seen terminating by their papillae in these calices ; and in one calix a papilla
is seen perforated by foramina, which are the terminal orifices of the urinifer-
ous tubes. Between the rounded bases of the conoidal bodies, and on the peri-
phery of the kidney is seen the cortical substance. —

THE URINARY BLADDER. - 127

which is a membranous cylindrical tube, rather flattened, and
between three and five lines in diameter, with some variations
in this respect.

The Ureters descend from the pelvis of the kidney so as to
pass obliquely across the psoas muscle and the great iliac
vessels. They are behind the peritoneum, but in contact with
it. They approach the pelvis near the junction of the os ilium
with the sacrum, and thence descend forwards and inwards,
surrounded with loose cellular membrane, to the lower part of
the bladder into which they are inserted at its external and
posterior part. They first penetrate obliquely the muscular
coat, and then proceed between the muscular and internal
coats from half an inch to an inch, in an oblique direction,
from without inwards and forwards, when they terminate by
small orifices in the internal coat, each of which is at an equal
distance, (rather more than an inch,) from the orifice of the
uretha, thus forming a triangle with it.

The ureters are said to have three coats. The exterior ap-
pears to be derived from the cellular substance ; within it is
another, which has been regarded very differently by different
anatomists ; some considering it as merely membranous, and
others as muscular. If the ureter be laid open and the internal
coat peeled off, the muscular structure of this coat is often very
perceptible.

The internal coat is called villous, or mucous, and is continued
from the internal coat of the bladder. Over this coat mucus is
constantly spread, which defends it from the acrimony of the
urine. It is very difficult to separate the two last mentioned
coats from each other.

The ureters receive blood-vessels and nerves from those of
the neighboring parts. Their internal coat is very vascular,
and is also very sensitive to irritation. The passage of a small
urinary calculus can be traced from the pelvis of the kidney
to the bladder, by the exquisite pain and the spasmodic affec-
tions which it often excites.

Of the Urinary Bladder.
The urinary bladder is a large sac, of a muscular and mem-

128 THE URINARY BLADDER.

branous structure, which occupies the anterior part of the cavity
of the pelvis, immediately within the ossa pubis.

The size of the bladder is in a continued state of variation,
according to the quantity of urine secreted. When moderately
distended, it is of an irregular oval form, but rather more flat at
its lower extremity than above. It varies in form according to the
different circumstances of the pelvis to which it has been subjected.

It is fixed firmly and immovably to the pelvis immediately
within the symphysis pubis; so that it is always to be found
there of a larger or smaller size. This fixture is produced by
the attachment of the lower portion of the fundus of the bladder
to the parts beneath it, but principally by the anterior ligaments
of the bladder which proceed one on each side from the lateral
surfaces of the prostate gland, and are inserted into the pubis
of the corresponding side at the lower part of the symphysis.
These ligaments are in fact the extension of a membrane,
(called by the French anatomists, the pelvic aponeurosis,)
which proceeds from the upper part of the pelvis to the
side of tlie prostate gland and bladder, and which may be
seen by turning off the peritoneum from the levator ani
muscle.* It is sometimes completely empty, and occupies
no more space than the thickness of its coats requires. When
moderately distended, it occupies a considerable portion of the
pelvis : when distention increases, it presses the parts posterior
to it against the sacrum, and extends itself above the brim of
the pelvis into the general cavity, rising not only to the umbili-
cus, but in some cases to the. epigastric region.

In males the relative situation of the bladder and rectum is
such, that the upper and middle part of the rectum is behind
the bladder; but the lower part of the rectum, following the
curve of the os sacrum and coccygis, is below the posterior
part of the bladder.

In females the vagina and uterus are situated between the
bladder and rectum ; so that the connexion of these last men-
tioned parts is very different in the two sexes.

* See Thesis on Femoral Hernia, Ace, by Gilbert Breschet. Paris, April,
1819. Colles' Surgical Anatomy, Dublin, 1811, for a more minute account of
this membrane. — h.

MUSCULAR COAT OF THE BLADDER.

129

The peritoneum is reflected at the anterior part of the brim
of the pelvis from the abdominal muscles, which it lines, to the
upper part of the bladder, which is generally contiguous to the
brim of the pelvis. It continues over to the posterior side of
the bladder, and passes down upon it some distance towards the
lower part ; but before it has arrived at the bottom, it is reflected
towards the sacrum.

In males it extends from the bladder to th^ rectum, and in
females, to the vagina and uterus ; so that [there is a consider-
able portion of the lower part of the bladder which is not
invested by the peritoneum. It also follows, that when the
bladder is extended into the abdomen, and rises above the brim
of the pelvis, that part of it which presents anteriorly, and is in
contact with the abdominal muscles, is without a covering of
peritoneum ; being below it.

— It is usual for anatomists and
pathologists to divide the bladder
when moderately distended into four
regions, for the purpose of descrip-
tion, viz. the middle part or body, the
top or upper fundus, the inferior part
or lower fundus, and the neck, at
which the urethra commences.
— In the foetus and young child, the
neck of the bladder is the most de-
pending portion. In the adult, the
bottom of the bladder is depressed
and expanded, so as to form a pouch
below the level of the neck, which is
technically known as the has fond. In this part the urine first
begins to accumulate when the organ has been emptied, and
calculi usually lodge.

* The posterior aspect of the male bladder ; the serous covering is remov-
ed in order to show the muscular coat. 1. The body of the bladder. 2. Its
upper fundus. 3. Its lower fundus or base. 4. The urachus. 5, 5. The ure-
ters. 6, 6. The vasa deferentia. 7, 7. The vesiculse seminales. 8. The
triangular area, corresponding with the trigonum vesicae through which the
bladder would be pierced, in puncturing the bladder through the rectum. The
dotted line forming the base of this triangular area, marks the extent to which the
recto- vesical fold of the peritoneum, descends upon the lower fundus of the bladder.

130 MUSCULAR COAT OF THE BLADDER.

— The diameter of the bas fond or lower fundus Is rather
greater laterally than in the antero-posterior direction. Its
lateral portions in both sexes are in contact with the levator aiii
muscles, and correspond to the spaces between the anus and
the tuberosities of the ischium. In the female, its middle por-
tion is in contact with the walls of the vagina ; in the male
with the rectum in the middle line, and with the vesiculae semi-
nales and the vasa deferentia upon the side. —

The bladder is composed of a coat consisting of muscular
fibres, of a stratum of cellular substance immediately within
this, and of an internal lining membrane, which has been called
villous ; but, as there are no villi perceptible on it, it may
be more properly denominated mucous.

It should be observed, that, in addition to these coats, the
bladder has a peculiar investment of the peritoneum, as has-
been already described ; and also of the common cellular mem-
brane, which is placed between it and every part to which it is
contiguous.

The Muscular Coat of the Bladder consists of fibres which
are not spread over it of a uniform thickness, but are thin in
some places, and in others are collected in fasciculi. They run
in every direction : some appear longitudinal, others circular,
and some oblique ; and there are interstices between them
which are occupied by cellular membrane. The longitudinal
fibres originate from the lower part of the bladder ; and as this
is the fixed part of that viscus, it is the place from which these
fibres must necessarily act. These fibres are generally exte-
rior. There is no arrangement of the muscular fibres to which
the term of sphincter can properly be applied ; but many ana-
tomists have thought that the fibres near the neck of the bladder,
by their separate contraction, might prevent the escape of
urine ; this sentiment, however, is contrary to that of several
very respectable writers.

The direction of the fibres, taken collectively, is such that,
when they all contract, the cavity of the bladder is completely
obliterated.

— The longitudinal fibres form the detrusor urince muscle of
some anatomists. They commence at the front and inferior part

SPHINCTER MUSCLE. 131

of the bladder, by four tendons — two on each side, one of
which comes from the pubic bone, and the other from the ramus
of the ischium, and spread out as they ascend over the anterior
surface of the bladder to the upper fundus. — They then con-
verge as they descend on the back part of the organ. Some of
these descending fibres may be traced by very careful dissection,
to an insertion in the back part of the prostate gland ; others
into the fascise covering the surface of the gland. A small deli-
cate band of fibres, according to Harrison, enters the notch at the
base of the gland, into which it is sometimes inserted, but can
frequently be traced forward between the mucous membrane
and the gland, in front of which it is attached by a delicate
tendon, at the lower part of the seminal caruncle or caput
gallinaginis. The office of this strip of fibres, is, he thinks,
to depress the uvula, and thus open the neck of the bladder,
and to draw down the seminal caruncle, (which he considers a
vascular erectile body like the glans penis,) into the cavity which
surrounds it, called sinus ^ocularis, out of the way of being
irritated by the urine. The fibres which cover the prostate
gland, connect it with the bladder in urination, and probably
force out its mucus to lubrify the passages.

— There has been much contrariety of opinion among anatomists
of reputation, in regard to the existence of a sphincter muscle
at the neck of the bladder, arising from the colorless appearance
and reticulated character of the fibres of the part.
— Those who deny the existence of a sphincter, as Bichat,
Cloquet, Marjolin, consider the neck of the bladder made up of
elastic fibro-ligamentous tissue, continuous with the longitudinal
fibres, and which expands under the action of the detrusor
muscle, to give passage to the urine. Those who admit the
existence of a sphincter, as C. Bell, Meckel, Horner, Harrison,
etc., describe it, however, very differently.

— The inferences drawn from diseased conditions of the organ,
are evidently much in favor of the existence of a muscular
sphincter; viz. the paralysis and incontinence of urine, resulting
from affection of the brain or spinal marrow, and the spasmodic
closures of the neck in strangury, resulting from neighboring
disease, or the acrimonious qualities of the urine.

132 INTERNAL OR MUCOUS COAT OF THE BLADDER.

— Harrison,* who has investigated it most recentl)', thus
describes It : — " When the several strata of longitudinal fibres
have been raised firom the front and lateral parts of this region,
the circular fibres of the bladder become distinct, but do not
appear so proportionably increased as were the longitudinal ;
but on detaching more completely the longitudinal strata, down
to the circumference of the very opening of the urethra, a dis-
tinctly fibrous, that is, muscular tissue is evident, bounding this
opening laterally and superiorly, but not below. This muscu-
lar fasciculus is not intimately connected to the general circular
coat ; it appears redder and of a closer texture, and will be
found to be attached to the fibrous or tendinous substance,
forming the anterior part of the trigone on each side of the
uvula, behind which it does not pass. The longitudinal fibres
are inserted partly into this semicircular muscle, much in the
same manner as the levatores ani are inserted into the circum-
ference of the anus. This structure we consider to be partly
elastic but essentially muscular ; it bounds the urethral opening
laterally and above, but not below ; the slight projection of the
uvula in the latter situation, and the elasticity and gentle state
of contraction natural to all the sphincter muscles, will preserve
this opening in a constantly closed state during the quiescent
and normal condition of the parts."

— For a description of the muscles of this part somewhat analo-
gous to the above, see Dr. Horner's Anatomy, vol. ii. p. 80,
4th edit. —

The cellular substance between the muscular and internal
coats is dense. It yields in a remarkable manner to distension,
and recovers its original dimensions very easily. From its
analogy to a similar coat in the intestines, it is called the Ner-
vous Coat.

The Internal Coat of the bladder is of a light color in the
dead subject, when it has been free from disease. It has been
called villous improperly ; for the villous structure is not appa-
rent upon its surface. Being continued from the integuments
of the body which are extended along the urethra, it has been
inferred, that the surface of this coat was formed by the epi-

* Vide article Bladder, by J. Harrison, Cyclop, of Anat. and Physiology. — p.

INTERNAL OR MUCOUS COAT OF THE BLADDER. 133

dermis ; and some respectable authors have supposed that they
had seen cases in which portions of the epidermis of the bladder
had separated and been discharged; but these appearances are
very equivocal, and it is by no means certain that an epidermis
exists there.*

The fasciculi of fibres of the muscular coat occasion this
coat to appear very irregular, but these irregularities correspond
exactly with the arrangement of the fibres of the muscular coat.

When the internal coat is separated by dissection from the
muscular, its surface is very smooth and uniform. In the recent
subject, when no disease has previously existed, it is always
spread over with mucus of a light color, but nearly transparent,
which can be easily scraped off. This mucus is spread upon
the surface so uniformly, that it must be derived from sources
which are situated upon every part of the surface; but these
sources are not very obvious. On the membrane of the nose
the orifices of many raucous ducts are very visible, but such
orifices are not to be seen on this surface. — Haller mentions
that he has seen mucous glands near the neck of the bladder;
and it is stated by the pupils of Desault, that, in one of his
courses, he pointed out a number of these glands, in a subject
who had been afflicted with a catarrhal affection of the bladder.

Notwithstanding that the sources of this mucus are obscure,
the quantity of it is sometimes immense. In some cases, where
the secretion is increased by the irritation of a calculus in the
bladder, the urine is rendered somewhat viscid and white-
colored by the mucus mixed with it ; which, after the urine
has been allowed to remain for some time, subsides in such
quantities as demonstrates that many ounces must be secreted
in the course of the twenty-four hours. The same circum-
stances occur without the irritation of calculus, in the disease
called catarrhus vesicas. f

It is probable that, in healthy persons, a great deal of it
passes off un perceived, being dissolved or diffused in the urine.

* In the fauces and the follicles of the tonsils, an effusion of coagulable
matter, in consequence of inflatnmation, often forms crusts that may be mis-
taken for sloughs of the integuments, although these integuments remain entire.

f In some cases this mucus soon becomes putrid, and during the putrefactive
process deposits its substance which appears to be calcareous.

VOL. II. 12

134 ORIFICE OF THE URETHRA.

From the quantity and the regular diffusion of this mucus on
the surface of the bladder, there is the greatest reason for be-
Ueving that it is effused from every part of the surface ; and it
is a question that has not been decided whether it is discharged
from glandular ducts too small to be perceived, or from the
exhalent extremities of the blood-vessels. It is probable that
the use of it is to defend the internal coat of the bladder from
the acrimony of the urine.

The symptoms of a stone in the bladder, as well as of several
other diseases, evince that this coat is endued with a great
degree of sensibility.

It is evident that the essential parts in the general structure
of the bladder are the muscular coat and the internal coat last
described : but in addition to this account of them, there are
some other important circumstances to be noted in the descrip-
tion of this organ. It has been already stated, that the form
of the bladder was an irregular oval, although it was somewhat
varied in different persons.* The oval form is not much
altered at the part called the neck of the bladder, where the
urethra passes off from it. The orifice of the urethra is situated
anteriorly near the lowermost part of the bladder. On the lower
surface of the urethra, at its commencement, and on the bottom
of the bladder, immediately connected with the urethra, is
situated the Prostate Gland, (to be hereafter described with
the organs of generation,) which is a firm body, that adheres
strongly both to the bladder and urethra. This circumstance
gives particular firmness and solidity to that part of the bladder.
It has also been observed, that the bladder is attached firmly
to the ossa pubis, at its neck, about the origin of the urethra.
Each of these circumstances has an effect upon the orifice of
the urethra ; and when the bladder is opened, and this orifice
is examined from within, it appears to be kept open by the
connexion of the bladder with the prostate, and has been very
justly compared to the opening of the neck of a bottle into the
great cavity of that vessel.f

* In the female, the vertical diameter of the bladder is less than in the male.
Its transverse diameter is greater in consequence of the greater width of the
pelvis in the female. — p.

f The late M. Lieutaud, and after him the French anatomists of the present

LIGAMENTS AND VESSELS OF THE BLADDER.

135

The orifices of the two ureters are at equal distances from the
orifices of the urethra, and form with it the angles of a triangle
called trigonum vesicas, (^trigone T^esicale.) That part of the
internal surface of the bladder which is within this triangular
space, is more smooth than the remainder of the same surface,

Fig. 156.*

day, have described a small tubercle at the lower and posterior part of the ori-
fice of the urethra, which resembles the uvula in form. It has not been noticed
here ; and M. Boyer states, that it is often scarcely perceptible. He, however,
makes a remark which is very worthy of attention, namely, that it is very sub-
ject to enlargement in old people, forming a tumor which impedes the discharge of
urine. Sabatier has also made the same observation.

* A side view of the viscera of the pelvis, showing the bladder and its sur-
rounding parts. 1. The symphysis pubis. 2. The bladder. 3. The recto-
vesical fold of peritoneum, passing from the anterior surface of the rectum
to the posterior part of the bladder ; from the upper part of the fundus of the
bladder it is reflected upon the abdominal parietgs. 4. The ureter. 5. The vas
deferens crossing the direction of the ureter. 6. The vesicula seminalis of the
right side. 7, 7. The prostate gland divided by a longitudinal section. 8, 8.
The section of a ring of elastic tissue encircling the prostatic portion of the
urethra at its commencement. 9. The prostatic portion of the urethra. 10.
The membranous portion, enclosed by the compressor urethra; muscle. 11. The
commencement of the corpus spongiosum penis, the bulb. 12. The anterior
ligaments of the bladder formed by the reflection of the pelvic fascia, from the
internal surface of the os pubis to the neck of the bladder. 13. The edge of
the pelvic fascia at the point where it is reflected upon the rectum. 14. An
interval between the pelvic fascia and deep perineal fascia, occupied by a plexus
of veins. 15. The deep perineal fascia ; its two layers. 16. Cowper's gland
of the right side situated between the two layers below the membranous portion
of the urethra. 17. The superficial perineal fascia ascending in front of the
root of the penis to become continuous with the dartos of the scrotum (18.)

136 GENERAL OBSERVATIONS.

probably in consequence of the adhesion of the bladder to the
prostate, and to other parts exterior to it.

The part of the bottom of the bladder, which is immediately
behind the triangular space, is rather lower than this space ;
and but a small portion of cellular membrane exists between it
and the rectum in males, and the vagina and it in females.

The upper part of the bladder is connected with the umbilicus
by means of a ligament, which passes between the peritoneum
and the abdominal muscles. This ligament consists of three
cords. One of these, which is in the middle, arises from the
coats of the bladder, and was, in the foetus, the duct called
urachus ; and the other two, which are connected to the bladder,
principally by cellular membrane, were originally the umbilical
arteries.* The middle cord is of a light color and fibrous
structure ; it is thickest at the bladder, and gradually diminishes
as it approaches the umbilicus. In a few instances it has been
found to be hollow. In its progress to the umbilicus it becomes
more or less blended with the linea alba or the tendons of the
abdominal muscles. The other cords are generally solid. After
passing from the umbilicus to the bladder they continue on the
sides of that viscus, and finally terminate at the hypogastric or
internal iliac artery.

In the very young subject these cords are invested by distinct
processes of the peritoneum, but their position is exterior to the
peritoneum. ,

As the bladder is situated very near most of the large rami-
fications of the hypogastric artery in the pelvis, it receives
branches from several of them ; viz. from the umbilical arteries
before they terminate ; from the pubic ; from the obturators, &-c.
These branches ramify in the cellular membrane exterior to the
muscular coat, and also in the cellular substance between the

19. The layer of the deep fascia which is prolonged to the rectum. 20. The
lower part of the levator ani ; its tibres are concealed by the anal fascia. 21.
The inferior segment of the funnel-shaped process given off from the posterior
layer of the deep perineal fascia, which is continuous with the recto-vesical
fascia of Tyrrell. The attachment of this fascia to the recto-vesical fold of
peritoneum is seen at 22.

* See the accounts of these parts in the description of the Abdomen of the
FcEtus.

GENERAL OBSERVATIONS. . 137

muscular and internal coats. It has been conjectured, thai their
termination in exhalents on the surface of the bladder are re-
markably nunfierous.

The veins correspond with the arteries ; but they are very
numerous on the lower and lateral parts of the bladder, and by
uniting with the veins of the rectum form a remarkable
plexus.

The Li/mphatic Vessels of this organ do not appear more
numerous than those of other parts. They pass on each side
of the bladder in the course of its blood-vessels, and unite with
the larger lymphatics, and the glands which lie upon the great
blood-vessels on the sides of the pelvis.

The Nerves of the bladder are derived both from the inter-
costal nerve and from the nerves of the medulla spinalis which
pass off through the sacrum ; and therefore the bladder is more
affected than the viscera of the abdomen, by injuries of the
medulla spinalis.

The action of the muscular fibres of the bladder in expelling urine, and the
effect of those fibres which are situated near the orifice of the urethra in
retaining it, can be considered with more advantage after the structure of the
urethra and the muscles connected with that canal have been described.

It has been stated that the internal coat of the bladder is ver)' sensible ; but it
may be added, that in consequence of disease about the neck of the bladder,
the natural sensibility appears most inordinately increased. When the inten-
sity of pain which accompanies these complaints, the frequent recurrence of
paroxysms, and their duration, are taken into view, there seems reason to
believe that none of the painful affections of the human race exceed those
which arise from certain diseases of the bladder. Happily these diseases are
not very common.

The functions of the kidneys is to secrete urine, and that of the bladder to retain
it, until the proper time for evacuation.

The urine may be regarded as an excrementitious fluid, which contains many
substances in solution that are constantly found in it, and many others that
are occasionally in it, which are taken as aliment or medicine, and pass to
the bladder with little, if any change. The odor of the roseleaf, the color of
rhubarb, &c., are occasionally perceiv^ed in urine.

The substances constantly found in urine are numerous. The chemical account
of the subject is so long that it cannot be detailed here ; but the student ought
to make himself acquainted with it, and he will read with great advantage
some of the modern treatises on Physiology and Animal Chemistry, and also
Thomson's Elements of Chemistry.

12*

138 MALE ORGANS OF GENERATION.

CHAPTER V.

OF THE MALE ORGANS OF GENERATION.

These organs consist first of the Testicles, and their appen-
dages.

2d. Of certain parts denominated the VesicuJcB Seminahs
and the Prostate Gland, which are situated near the commence-
ment of the urethra, and are subservient to the purposes of
generation.

3d. Of the Penis.

Of the Testicles and their Appendages.

The Testicles are two bodies of a flattened oval form.
Each of them has a protuberance on its upper and posterior
part called Epididymis, and is connected to parts within the
cavity of the abdomen by a thick cord, which proceeds through
the abdominal ring. Each testicle also appears to be contained
in a sac, which is suspended by this cord and covered by the
common integuments.

— The testicle of the right side is usually suspended a little
higher and is frequently larger than that of the left. They
attain their fullest development in middle life, when they are
an inch and a half long, an inch wide and three quarters of an
inch in thickness. In old age they are shrunken in size, from
the fluids being attracted to it in less quantity in consequence
of the impaired sensibility of the organ. The upper extremity
of each testicle has a slight inclination forwards, which is
greatly increased in preparing it for demonstration by breaking
up its posterior attachments.

— The coverings of the testicles are formed from without
inwards, of five tunics. 1. The Scrotum. 2. The dartos

THE SCROTUM. 139

muscle. 3. The tunica vaginalis communis, so called from its
covering in closely both tbe cord and testicle of each side,
and sometimes named tunica eli/throides, from the cremaster
muscle which is spread over it. 4. Of the tunica serosa or
tunica vaginalis testis — and 5. Of the tunica albuginea, or
proper coat of the testicle. —

That portion of the common integuments which forms the
external covering of the testicles, is denominated,

The Scrotum.

The skin of the scrotum, although it is very often in a state
of corrugation, has the same structure with that on other parts
of the body, except that it is rather thinner and more delicate.
The superior delicacy of this portion of the skin is evinced by
the great irritation produced by the application of stimulating
substances, and the desquamation of the cuticle, which seems to
be the eflect of irritation. There are many sebaceous follicles
in this portion of skin ; and after puberty there are often a few
long hairs growing out of it, the bulbs of which are often very
conspicuous. There is a small raised line in the middle of this
skin, which commences at the root of the penis, and proceeds
backwards, dividing it into two equal parts: this line is denomi-
nated Raphe.

The corrugation which so often takes place in the skin of the
scrotum, appears to be occasioned by the contraction of certain
fibres, which are in the cellular substance immediately within
it. This cellular substance appears to be. attached in a parti-
cular way to the skin ; and it also invests each testicle in such
a manner, that when they are withdrawn, a cavity is left in it.
It has long been observed, that no adipose matter is found in
this cellular substance : but it is often distended with water in
hydropic diseases. As the contraction and corrugation of the
scrotum has been imputed to this substance, it has been exam-
ined with particular attention by anatomists, and very different
sentiments have been entertained respecting it. While
some dissectors have asserted that muscular fibres could be
seen in it, which they have denominated the Dartos Muscle ;
others have said that this substance was simply cellular, and

140 THE DARTOS.

without any musclar fibres. This difference of sentiment may
possibly have arisen from the different conditions of this part in
different subjects ; for in some cases there are appearances
which seem to justify the assertion that muscular fibres exist in
this structure.

After the testicles are removed, so as to leave the cellular
substance, connected with the skin, if the scrotum be inverted,
and this substance examined in a strong light, many fibres will
appear superadded to the common cellular structure ; and
sometimes their color can be distinguished to be red. It is
not asserted that this will be uniformly the case ; but certainly
it has often been observed in this way.

The existence of an organ which possesses the power of
contraction, within the skin of the scrotum and connected to it,
is evinced by the corrugation which takes place when the
scrotum is suddenly exposed to cold, after having been very
warm. This corrugation occurs in a very sudden and rapid
manner, in some cases, in which the wounded scrotum is thus
exposed for the purpose of dressing : for example, upon
removing an emolient poultice from this part some days after
the operation for the cure of hydrops testis by incision, if the
air of the chamber be cool, a motion of the scrotum will
take place, almost equal to the peristaltic movements of the
intestines.

The Arteries of the scrotum are derived from two sources.
One or two small arteries, which arise from the femoral artery,
between Poupart's ligament and the origin of the profunda,
are spent upon it. These are called the external pudic arteries.
It also receives some small branches from the internal pudic
artery.

The Nerves of the scrotum are principally derived from the
lumbar nerves.

The Darios,

— Considered as a muscle, arises on each side from the rami
of the pubis and ischium, and passes down to the raphe of the
scrotum, to which it is closely united. It is there reflected up
in juxtaposition with its fellow of the opposite side, so as to form

THE SPERMATIC CORD. 141

the septum scroti, and leave a pouch on each side for the lod<^-
ment of the testicles, cords, and three inner tunics, and is finally
inserted upon the lower portion of the corpus spongiosum uretlirse.
Meckel suggested that the tissue of the dartos forms the transi-
tion between cellular tissue and muscular fibre, and that there
exists between ft and the other muscles of the body, the same
relation as exists between the muscles of the superior and inle-
rior animals ; in the latter of which the fibrous structure, is but
feebly developed.

The so-called dartos muscle, is now generally admitted as
holding the place of superficial fascia to the scrotum, and con-
sisting of the modification of cellular membrane known, as the
red contractile fibrous tissue.

The Spermatic Cord.

The cord which proceeds to the testicle, through the abdo-
minal ring, appears 'at first view like a bundle of muscular fibres ;
but it consists of an artery and veins with many lymphatic ves-
sels and nerves, and the excretory duct of the testicle ; these
are connected to each other by cellular substance, and covered
by an expansion of muscular fibres, which are derived from the
lower edge of the internal oblique muscle of the abdomen, and
continue from it to the upper part of the testicle. These fibres
constitute the Cremasier Muscle.

— This cellular substance which encloses both the cord and
testicle, with the cremaster muscle (elythroid tunic) on its outer
face, forms the tunica vaginalis cummunis. It is a thin layer,
and serves to connect the dartos, to the tunica serosa, within.
— The cremaster* muscle, is formed by an arched arrangement
of the fibres of ilie internal oblique and transversalis muscles
of the abdomen, according to the observations of J. Cloquet,
made upon a considerable number of foetuses, before, during,
and after the descent of the testes. The fibres originally passed
from Poupart's ligament to the pubis, nearly in a straight direc-
tion ; but as the testicle descended tlirough its canal to the scro-
tum, these fibres were pushed before it and formed into arches or
loops, which increased gradually in length, partly by distention

* From X/jcynacj, suspendo. — v.

142

THE CREMASTER.

Fig. 157.* and partly by interstitial growth,

as the testicle proceeded in its
descent. Hence when it is de-
scribed as a distinct muscle, the
origin and insertion of the cre-
inaster are given the same as that
of the inferior fibres of the inter-
nal oblique. It arises from Pou-
part's ligament, passes down on
the outer side of the tunica vagi-
nalis communis of the cord and
testicle, and passes up on the in-
ner side to be inserted into the
pubis. It gives a complete red-
dish coloring to these parts, called
tunica elythroida.f

— Its redness disappears in emaciated or dropsical subjects, and

in cases of hernia the distention causes it to separate apparently

into two bundles of fibres, internal and external.

— Its action is to draw the testicle upwards and support it: it is

distinct from that of the dartos.J

— Fig. 157, from Sir A. Cooper's work on the testis, is a good

illustiation of its structure. —

* Fig. 157. ff, d, Rectus abdominis, b, Superficial fascia of the cord, and
tendon of external oblique, c, Internal oblique, e, Descending fibres of inter-
nal oblique, or origin of crennaster muscle from Poupart's ligament. /, Inser-
tion of cremaster muscle on the pubis, g, g, Descending and ascending fibres.
h, The loops M'hich are produced in the cremaster by the descent of the testicle.
i, Testis, cov^ered by the tunica vaginalis to which is attached, by a sort of in-
sertion, the loops of the cremaster. —

f From EXul^oc, a sheath. —

:j: Mr. Curling explains the development of the cremaster in a different man-
ner.— He considers it the muscle of the gubernaculum, and states that it follows
this cord up into the abdomen to be attached to the lower end of the testicle be-
fore the descent of this organ, and that by its lower end the muscle is connected
by three separate attachments to the pubis, to Poupart's ligament and to the
bottom of the scrotum. The contraction of these separate bands, is the means
he believes by which the testicle is made to descend. — This description of Mr.
Curling is however by no means conclusive or satisfactory. — It is diflScult to
conceive, how the same muscle, can at one time have for its office thai of draw-
ing the testicle down, and at another as is always the case after birth, that of
raising it up in the scrotum. — p.

VESSELS AND NERVES OF THE CORD. 143

The artery above mentioned is called the Spermatic. Ii
commonly arises from the front of the aorta, very near its
fellow, at a small distance below the emulgents, and is not
much larger than a crow's quill. It proceeds downwards
behind the peritoneum and before the psoas muscle, and ureter.
— While it is in contact with the psoas muscle, it joins the
ramifications of the vein. It afterwards meets the vas deferens,
and proceeds through the abdominal ring to the back part of
the testis. Before it arrives at the testis, it divides into several
branches, two of which generally go to the epididymis, and the
others penetrate the tunica albuginea on the upper and back of
the testicle, and ramify very minutely on the fine membranous
partitions which exist on that body.

In addition to the spermatic artery, there is a small twig from
the umbilical branch of the hypogastric, which passes to the
spermatic cord along the vas deferens.

The branches of the spermatic vein are much larger than
those of the artery : several of them proceed from the testicle
so as to correspond with the arterial branches ; and in addition
to these there are many smaller, which also arise from the testi-
cle and epididymis. In their course up the cord they ramify,
and again unite so as to form a considerable plexus, which is
called the Corpus Pampiniforme, and constitutes a considerable
part of the volume of the spermatic cord.

As they proceed upwards, they unite into a few larger veins ;
and finally, on the psoas muscle, they generally form one trunk,
which continues upwards so as to unite with the vena cava on
the right side, and the emulgent vein on the left.

Sometimes, but not often, there are several spermatic veins on
each side.

The Lymphatic Vessels of the testicle are very numerous,
considering the size of tlie organ. Six or eight, and sometimes
more, large trunks have been injected, running upon the cord, and
continuing to the glands on the back part of the abdomen.

The JServes of the testicle are derived from those which
supply the viscera of the abdomen, and are to be found in the
cord, although they can scarcely be traced to the testicle. A
small plexus, called the spermatic, is formed by fibres from the

144 TUNICA VAGINALIS TESTIS.

renul plexus, and from the sympathetic nerve. These fibres
accompany the spermatic vessels, and in all probability enter the
body of the testis and the epididymis. The spermatic cord and
cremaster muscle receive filaments from the second lumbar nerve.

In addition to these vessels, the Vas Deferens, which is much
firmer than either of them, is always to be distinguished in the
back part of the cord.

They are all covered in front and on the sides by the cremas-
ter muscle, which passes with them from the lower margin of the
internal oblique, through the abdominal ring, and continues to the
upper part of the external coat of the testicle, which is a sac
apparently containing that organ, and upon this sac it is spread
out and terminates.

The Turdca Vaginalis.

The External Coat of the testicle, which is commonly called
the Tunica Vaginalis, is a complete sac which encloses the tes-
ticle as the pericardium encloses the heart. It covers the body
of the testicle and epididymis, and adheres closely to them.* —
It is then reflected from them so as to form a loose thin sac.
{Tunica Vaginalis Rcjlexa,) which appears to contain them.
The cavity of the tunica vaginalis commonly extends above the
body of the testis up the cord, and is oval or pyriform. — This
sac is so reflected from the body of the testicle that there is a
place on the upper and back part of that body, at which the
blood-vessels enter it, without penetrating the sac.

It resembles the peritoneum and other serous membranes in
texture, and is therefore thin and delicate. It always contains a
quantity of moisture, sufficient to lubricate the surface which it
forms.

When the tunica vaginalis is laid open, the testicle appears as
if it were contained in the posterior part of its cavity.
— At the upper part of the testicle near the point at which it is
connected with the head of the epididymis we commonly find a
little hydaliforme body, first noticed by Morgogni, called the
hydatis tunica vaginalis.

* This part of the vaginal tunic, is called the tunica vaginalis propria. — p.

TUNICA ALBUGINEA. 145

The testicles, as has been already stated, are of a flattened
oval form. Their position is somewhat oblique, so that their
upper extremities look upwards and forwards, their lower
extremities downwards and backwards, and their edges present
forwards and backwards.

The body of the testicle is very firm, in consequence of its
enclosure in a very firm coat called Tunica Alhuginea. Upon
the upper and posterior part of it is the protuberant substance,
called Epididymis, which is less firm, being exterior to the
tunica albuginea. The blood-vessels of the testicle pass into
it on the posterior edge, at some distance below the upper
end.

The Tunica Albuginea,

In which the body of the testicle is commonly enclosed,
is firm and dense ; and upon this coat its particular form depends.
It is of a whitish color, and has a smooth external surface.
It is thick as well as strong. The epididymis is exterior to it.
It is only perforated by the blood-vessels, lymphatics and nerves,
and by the vasa efFerentia, which carry out the secretion of the
testis. One portion of the tunica vaginalis adheres very closely
to it, and the other appears to contain it. The portion which
adheres to it is with difficulty separated, but it is a distinct
membrane.

— The tunica albuginea is a fibrous membrane, considerably
thinner than the sclerotic coat of the eye. It is very strong and
resisting, and is susceptible of very considerable distention,
when the dilating cause acts slowly, as in the engorgements of
the testicle called hernia humoralis. It is also endowed with
retractile properties, as is seen when the distending cause has
ceased to act. Its internal surface, which is immediately applied
upon the substance of the gland, gives origin to a great number
of flattened filaments or septae, which divide the gland into
compartments for the separate lobules, and upon which the
blood-vessels run, to be distributed in the glandular tissue.
These septae are directed to the back part of the organ neces-
sarily, (as that is the direction in which the efferent ducts of the
testis pass,) and form by their accumulation that thickened,
oblong, fibrous mass, called the corpus highmorianum. The
VOL. II. 13

146 THE BODY OF THE TESTICLE.

blood-vessels with their connecting cellular tissue, form on the
inner surface of the tunic a delicate membrane called the tunica
vasculosa.

The Epididymis

Differs in color from the testicle, being more or less reddish.
It commences at the upper and anterior extremity of the testicle,
and passes down the posterior edge to the lower end.

At the commencement the epididymis is somewhat rounded
in form, and its upper part, or head, has been called the globus
major: as it descends it lessens, and about the middle of the
testicle it is flattish. Its lower end is rounded and forms the
globus minor.

It is firmly attached to the body of the testicle, at the upper
end, where the vasa efFerentia pass to it ; and it is also attached
to it below ; but at the middle it appears nearly detached from
it. It has therefore been compared to an arch resting with its
two extremities on the back of the testis ; it is, however, in con-
tact with it at its middle ; but about the middle it only adheres
by one of its edges to the body of the testis, and generally by
its internal edge. It has a coat which is less firm than the
tunica albuginea of the testicle, described on the last page.
The tunica vaginalis of the testicle is so reflected as to cover
a great part of the epididymis which is not in contact with the
testicle, and also of those surfaces of the epididymis and testis
which are in contact with each other and do not adhere.

The Body of the Testicle.

When the tunica albuginea is cut through, and the substance
of the testicle examined, it appears to consist of a soft pulpy
substance of convoluted threads, of a yellowish brown color,
which is divided into separate portions by very delicate septa,
attached to the internal surface of the tunica albuginea at the
posterior part of the testicle. After maceration, by using
a fine needle, to detach them from the cellular substance, these
threads may be drawn out to a great length. In some animals
they are larger than in the human species; in them, it is said,
they are evidently hollow, and that very small blood-vessels
appear in their coats. When mercury is injected into the

CORPUS HIGHMORIA.NUM OR MEDIASTINUM TESTIS.

147

vas deferens, or excretory duct of the testis, in a retrograde
course, it can be perceived in these ducts in the human subject.
Fig. 158.* These delicate septa, or partitions, are

united to the internal surface of the tunica
albuginea at the posterior part of the testi-
cle, at which place there is a body called
Corpus Highmorianum, which has been
regarded very differently by different anato-
mists. It is a long whitish substance, which
extends lengthwise on the posterior part of
the testis; and was supposed by Haller to
resemble one of the salivary ducts. It is
now, however, generally agreed to be of a
fibrous structure, and to contain and support
the ducts which pass from the substance of
the testicle to the epididymis.

The blood-vessels pass into the body of the testicle upon
these septa, and are continued from them to the filaments or
tubes of which the body of the testicle consists. As in some
animals blood-vessels are distinguished on these tubes, there is
the greatest reason to believe that a direct communication sub-
sists between the two without the intervention of any other
structure, no other structure having been discovered : but at
the same time it ought to be observed, that these tubes have not
yet been injected from the blood-vessels. Some ingenious anat-
omists have injected the artery going to the testicle so success-
fully that the injection has passed from it Into the veins coming
out of the testicle ; but it is not now said by any of them, that
they have filled the tubes in this manner.

* A transverse section of the testicle. 1. The cavity of the tunica vagina-
lis ; the most external layer is the tunica vaginalis reflexa ; and that in contact
with the organ, the tunica vaginalis testis. 2. The tunica albuginea. 3. The
mediastinum testis, giving off numerous fibrous cords in a radiated direction to
the internal surface of the tunica albuginea. The cut extremities of the ves-
sels below the number belong to the rete testis ; and those above to the arteries
and veins of the organ. 4. The tunica vasculosa, or pia mater testis. 5. One
of the lobules, consisting of the convolutions of the tubuli seminiferi, and ter-
minating by a single duct — the vas rectum. Corresponding lobules are seen
betweeu the other fibrous cords of the mediastinum. 6. Section of the epi-
didymis.

148

STRUCTURE OF THE TESTICLE, ETC.

Mercury will pass into these vessels from the excretory duct
of the testicle ; and by means of an injection in that way, the
structure of the testicle can be unraveled.

This structure is as follows : the cavity formed by the tunica
albuginea is divided into a number of apartments by the very
thin septa or partitions above mentioned. The filamentary or
tubular matter which fills each of these chambers, consists of a
seminiferous duct convoluted so as to form a lobule. Three
hundred of these, according to Monro, may be counted in each
testicle : from each one proceeds a number of small tubes or
vessels, which observe a straight course : they are, therefore,
called Vasa Recta. These vasa recta unite with each other
and form a net-work on the back of the testis, within the tunica
albuginea, which is called Rete Testis, Fig. 159.*

From this net-work other vessels, from
twelve to eighteen in number, de-
nominated T^asa Efferentia, proceed
through the albuginea to the epididy-
mis. These vessels are convoluted in
such a manner as to form bundles
of a conical form, which are called
Coni Vasculosi. The number of these
corresponds with the number of the
vasa efferentia, and they compose about
one-third of the epididymis, viz. all the
upper part of it. The single tubes
which form each of these cones, succes-
sively unite into one duct, which is con-
voluted so as to form all the remainder
of the epididymis and is turned up-
wards on the back of the testicle ; the
tube gradually enlarges and is less convoluted, and finally becomes

* Anatomy of the testis. 1, 1. The tunica albuginea. 2, 2. The medias-
tinum testis. 3, 3. The lobuli testis. 4, 4. The vasa recta. 5, 5. The rete
testis. 6. The vasa efferentia. of which five only are represented in this dia-
gram. 7. The coni vasculosi, constituting the globus major of the epididymis.
8. The body of the epididymis. 9. The globus minor of the epididymis.
10. The vas deferens. 11. The vasculum aberrans.

TUBITLI SEMINIFERI. 149

Straight : it then takes the name of Vas Deferens, and con-
tinues on the back of the testicle and at the inner side of the
epididymis to the spermatic cord.*f

A small solitary vessel or duct, has been observed by Haller,
Monro, and several other anatomists, to proceed from near the
upper part of the epididymis : sometimes it unites to the epi-
didymis below, and sometimes it proceeds upwards. The nature
of this vessel has not been ascertained with certainty.
— This duct or appendix which was named vasculum aherrans
by Haller, discharges mucus into the vas deferens. Occasion-
ally two or three are met with, all of which commence, by a
cul de sac, or coecal extremity.

— Monro and Lauth, have both endeavored to estimate the
length of the seminiferous ducts. This, however, could not be
done directly, in consequence of the fragility of the ducts.
Their estimate is founded partly on measurement, and partly on
calculation, and can only be considered an approximation to the
truth. The estimate of Monro exceeds that of Lauth. Accord-
ing to the former, there are three hundred lobules, each one con-
sisting of a single seminiferous duct, arranged in the lobules in
a series of close serpentine doublings, which are held together
by some delicate cellular tissue. When this cellular tissue is
destroyed by maceration, for a short time, each duct may be
drawn out with ease, and resembles the unraveled thread of a

* De Graff appears to have been the first anatomist who made much pro-
gress in the successful investigation of the structure of the testicle; and Haller
ought to be mentioned next to him, on account of the plate exhibiting this
structure, and the explanation of it, which he published in the Philosophical
Transactions of London, for 1749. This plate has been republished by the
second Monro, in the Literary and Physical Essays of Edinburgh, and also in
his Inaugural Thesis. Haller has likewise republished it in his Opera Minora.
It represents not only the vasa efferentia, and the cones formed by their convo-
lutions, but also the rete testis, and the vasa recta. Haller could inject no
farther than this ; but JMonro and Hunter soon afier succeeded so as to fill a
considerable portion of the body of the testicle with mercury, injected by the
vas deferens.

f In Mr. Charles Bell's Anatomical Collection in London, there is a prepara-
tion by his assistant, Mr. Shaw, in which the tubuli testis are completely
injected with quicksilver and unraveled. I saw also in Leyden, one nearly as
successfully executed by Professor Sandifort. — h.
13*

150

VAS DEFERENS.

Stocking. The diameter of each duct is gi^th part of an inch,
and its length a little short of seventeen and a half feet. The
aggregate length of the whole will be, according to the sanne
writer, about 5208 feet, or a little less than a mile. In the rete
testis, these ducts anastomose very freely together, for the pur-
pose, according to Laulh,* of more highly assimilating the
fluid they carry, by exposing it to a more extensive surface of
living tissue. The length of each efferent duct, with its conus
vasculosus, he has found from seven to eight inches. The
length of the convoluted duct forming the remainder of the
epididymis, he has seen to vary in different individuals, from
Fig. 160.f sixteen to twenty-nine feet : Mon-

ro estimates it at thirty-one. Lauth
estimates the entire length of the
seminal canals at 1750 feet ; —
Krause of Hanover, considers their
mean length to be fairly stated 1015
feet. — Most observers now agree
in estimating their diameter from
of a line. There are but few instances, it
appears, in which anatomists have succeeded completely in
filling the tubuli testis with quicksilver, from the vas deferens.
Hunter is said to have succeeded admirably in a preparation,
which he sent as a present, to Catharine the second of Russia.
Success in the preparation of this part, is dependent more upon
perseverence and good fortune, than anatomical skill. It is
useless, however, to make the effort except upon a healthy
gland, taken from a subject who has died of some wasting dis-
ease, in which excitement in the organ has so long ceased, as
to leave no obstructing fluid in the ducts. I have now in my
cabinet, a preparation, in which I succeeded a few years ago,
in filling with quicksilver to all appearance the whole of the
tubular structure of the testicle.

the

to the

* Memoir Surle testicle humane: T. Lauth, Strasburg, 1833.
t a, Tubuli seminiferi, greatly magnified, b, Mode of anastomosis of these
tubes, c, Blood-vessels ramifying on these tubes. —

COURSE OF THE VAS DEFERENS.

151

— According to Vauquelin, the semen masculinum consists
chemically, of water 0.90 ; animal mucus 0.06 ; phosphate of
lime 0.03; soda 0.01.—

Fig. 161.* Fig. 162.t

Descent jf the Testis
— The testis is placed in the foetus nearly in the same situation
as the ovarium is found in the female. This is seemingly for
the purpose of ensuring its primitive development, which
would have been less certain, if it had been from the first
lodged in the scrotum, and the spermatic artery obliged to be
formed through so long a space to reach it.

— In the early periods of foetal life, the testis, as before
observed, is placed immediately below the kidney of the same
side. Between the fifth and sixth months, it is lodged on the
psoas muscle. At the eighth month it is found in the scrotum.
Its descent is mainly brought about by the action of the

* A diagram illustrating the descent of the testis. 1. The testis. 2. The
epididymis. 3, 3. The peritoneum. 4. The pouch formed around the testis
by the peritoneum. 5. The pubic portion of the cremaster attached to the
lower part of the testis. 6. The portion of the cremaster attached to Poupart's
ligament. The mode of eversion of the cremaster is shown by these lines.
7. The gubernaculum, attached to the bottom of the scrotum, and becoming
shortened by the contraction of the muscular fibres which surround it. 8, 8.
The cavity of the scrotum. 9. The peritoneal cavity.

t In this figure the testis has completed its descent. The gubernaculum is
shortened to its utmost, and the cremaster completely everted. The pouch of
peritoneum above the testis is compressed so as to form a tubular canal. 1. A
doited line marks the point at which the tunica vaginalis will terminate supe-
riorly ; and the figure 2 its cavity. 3. The peritoneal cavity.

152 DESCENT OF THE TESTIS.

gubernaculuin testis. This consists of a cord formed of several
stroncr fibres, which seem to belong to that peculiar tissue,
described vol. i. p. 298, as the contractile. It is lodged in
the inguinal canal, which is found already formed, and is
attached by one end, to the lower extremity of the testis and
epididymis and by the other to the cellular tissue of the scrotum,
with which it seems to be continuous. The peritoneum of the
lower part of the abdomen passes down upon and adheres to
this contractile cord so as to form a small pouch in the inguinal
canal, which is carried down before the testicle, and ultimately
forms the tunica vaginalis rejiexa of the adult, while that
portion of the peritoneum that covered the testicle in the
abdomen, and is brought down with it, forms, according to Sir
A. Cooper, or rather remains the tunica vaginalis testis.
Soon after the descent of the organ, the serous cavity of the
tunica vaginalis, is usually closed by the process of adhesion,
so as to cut off all communication with the serous cavity of the
abdomen. The process of closing begins above at the internal
rino-, and continues gradually down the track of the spermatic
cord. Occasionally, from some cause, as the sliding into it of
a portion of the intestine or omentum, the orifice of communi-
cation is not shut up. The infant is then liable to the forms of
hydrocele and hernia, which have been called congenital. In
all cases the testicle is not brought down by the gubernaculum.
It may be left near the place of its first development, or
partially depressed and lodged in some part of the inguinal canal.
In the latter case it is exposed to injury from the action of the
muscles, and to external violence, and is often found in the end
to become atrophied from pressure, or to degenerate into
malignant disease.

^The pressure of the descending intestine as in the formation

of congenital hernia, has in some cases carried the testicle down
to its proper location.

— In some instances the testis has been observed, without any
cause of this sort, but probably from some other connected with
the natural excitement of the epoch to complete its descent
about the period of puberty. If the testis remains in the

VAS DEFERENS. 153

cavity, it increases to nearly its natural size, and seems to gain
the power of executing its proper functions. —

The Vas Deferens

Is a very firm tube, about one line in diameter, which is not
perfectly cylindrical exteriorly, although the cavity formed by it
is so. This cavity is so small in diameter, that it will only
admit a fine bristle. The coats of the duct have, of course, a
considerable thickness. The internal coat forms a soft surface,
analogous to that of the mucous membranes : the external is
firm, and its texture resembles that of cartilage. Owing to the
small size of the cavity, the internal coat has not been separated
from the external.

It passes upwards in the posterior part of the spermatic cord,
and continues with it through the abdominal ring, under and
exterior to the peritoneum ; soon after this it leaves the qord
and dips down into the cavity of the pelvis, forming a curve
on the side of the bladder, and proceeding backwards, down-
wards, and inwards. In this course it crosses the ureter, and
passes between it and the bladder. On the lower part of the
bladder the two vasa deferentia approach each other so gra-
dually that they appear to be nearly parallel. They proceed
forward between the vesiculse seminales, which are two bodies
irregularly convoluted, that are placed in a converging position
with respect to each other, and communicate with the vasa
deferentia. The vasa deferentia finally terminate almost in
contact with each other in the posterior part of the prostate
where they perforate the urethra. At the distance of about
two inches and a half from their teftnination they enlarge in
diameter, and become somewhat convoluted. At the posterior
margin of the prostate they come in contact with the anterior
extremities of the vesiculae seminales, and unite with them.
After this union they diminish in size, and become conical ;
and passing a short distance through the substance of the pros-
tate, during which they approach each other more rapidly,
they penetrate the urethra, so as to open in it on each side of
a small tubercle, called the Caput Gallinaginis, soon to be
described.

154 VESICUL^ SEMINALES.

Of the VesiculcB Seminales and the Prostate Gland.

The Vesicula Seminales are two bodies of a whitish color,
and irregular form, being broad and flat at their posterior ex-
tremities, and terminating in a point at the other. They are
about two inches and a half in length, and six or seven lines
in diameter at their widest part. Their surfaces are so convo-
luted, that they have been compared to those of the brain.
They are situated between the rectum and bladder, and are
connected to each other by cellular membrane.

When the vesiculae seminales are laid open by an incision,
they appear to consist of cells of a considerable size, irregularly
arranged ; but when they are carefully examined exteriorly, and
the cellular membrane about them is detached and divided, they
appear to be formed by a tube of rather more than two lines in
diameter and four or five inches in length, which terminates,
like the caecum, in a closed extremity. From this tube proceed
from ten to fifteen short branches, which are closed in the same
manner. All these tubes are convoluted so as to assume the
form of the vesiculae seminales above described ; and they are
fixed in this convoluted state by cellular membrane, which
firmly connects their different parts to each other. It is obvious
that tubes thus convoluted, when cut into will exhibit the appear-
ance of cells, as in the present instance.

This convoluted tube composing the vesiculae seminales, ter-
minates in a very short duct, which is nearly of the same dia-
meter with the vas deferens ; this duct joins the vas deferens so
as to form an acute angle.

From the union of the vesiculae seminales with the vas defe-
rens on each side, a canal, which seems to be the continuation
of the vas deferens, proceeds through part of the prostate to the
urethra, which it perforates. These canals are from eight to
twelve lines in length ; they are conical in form, their largest
extremity being equal to the vas deferens at that part.

If the air or any other fluid be injected through the vas de-
ferens into the urethra, it will pass at the same time into the
vesiculae seminales, and distend them. It has been observed,
that a fluid passes in this manner much more readily from the

VESICULffi SEMINALES. 155

vasa deferentia into the vesiculae seminales, than it does from
these last mentioned organs into the duct.

The union formed by the short duct of the seminal vesicle
and the vas deferens of each side constitutes the ductus ejacula-
torius, which is about an inch in length, and runs in close con-
tact and parallel with its fellow of the opposite side, between
the middle and lateral lobes of the prostate, and opens
obliquely into the urethra by a small oblong orifice in the
caput gallinaginis. Each ejaculatory duct is a conoidal tube,
its apex being at its orifice in the urethra. Hence fluids pass
so readily into the seminal vesicles, when injected along the
vasa deferentia. The diminution of the duct at its urethral
orifice, will also increase the force of the jet, by which the fluid
of the vesicle is ejected, when spasmodically compressed by
the levator ani muscle. — ,

These organs were generally regarded as reservoirs of semen,
and analogous to the gall-bladder in their functions, until the
late Mr. J. Hunter published his opinion that they were not
intended to contain semen, but to secrete a peculiar mucus
subservient to the purpose of generation.

He states the following facts in support of his opinion.

A fluid, very different from semen, is found after death in
the vesiculae seminales.

In persons who have lost one testicle, a considerable time
before death, the vesiculae seminales on each side are equally
distended with this peculiar fluid. In the case of a person who
had a deficiency of the epididymis on one side, and of the vas
deferens on the other, the vesiculae were filled with a peculiar
fluid ! •

The sensation arising from redundance of the secretion of
the testis, is referred to the testis, and not to the vesiculae
seminales.

In some animals there is no connexion between the vasa
deferentia and the vesiculae seminales.

— And in many others as the dog, there are no vesiculae
to be met with. —

See Observations on certain Parts' of the Animal Economy,
by John Hunter.

156 THE PROSTATE GLAND.

The Prostate Gland

Is situated on the under and posterior part of the neck of the
bladder, so as to surround the urethra. Its form has some
resemblance to that of the horse-chestnut, but it has a notch on
the basis like that of the figure of the heart on playing cards,
and it is much larger than the chestnut of this part of America.
The basis of this body is posterior, and its apex anterior; its
position is oblique, between the rectum and the symphysis
pubis. Below there is in some cases a small furrow, which,
in addition to the notch above, gives to the gland an appear-
ance of being divided into two lobes. By turning away the
vesiculae seminales and vasa deferentia from the under surface
of the bladder, we bring into view a small tubercle at the
upper part of jhe base of the prostate, called by Sir Everard
Home the third lobe. When diseased it projects into the
cavity of the bladder.*

The prostate adheres to the urethra and neck of the bladder.
Its consistence is very firm and dense, resembling the induration
of scirrhus rather more than the ordinary texture of glands.

This gland receives small branches from the neighboring
blood-vessels, and has no artery of considerable size exclusively
appropriated to it.

As it lies in close contact with the urethra, the ducts which
pass between it and the urethra are not to be seen separate
from these bodies : but ducts can be seen in the substance of
the gland, which perforate the urethra, and open on the sides
of the caput gallinaginis to the number of five or six on each
side. By pressure a small quantity of a whitish fluid can be
forced from these orifices, which is rather viscid, and coagulable
in alcohol.

The particular use of this fluid is not known.
— Fig. 163, is a magnified representation of a section of the
prostate gland, which serves to show its vesicular structure.

* In a healthy state, the third lobe forms but a slight elevation in the cavity
of the bladder, covered by mucous membrane, called uvula vesicae. — p.

PROSTATE GLAND.

157

Fig. 163.* — From these vesicles or modified

follicles, originate many excretory
canals, which unite together so as
to constitute about twelve ducts,
that open into the urethra by the
sides of the caput gallinaginis.
— Loder asserts that there are
from thirty-two to forty-four of
these excretory ducts — but this is
probably an error. I have sought
for these ducts in several cases where they were so much en-
larged from catarrhal inflammation of the bladder, as to admit
the end of a small probe, without being able to detect more
than the number above mentioned. The whole structure of
the prostate appears to be that of a compound mucous gland,
designed to throw a lubrifying mucus in great abundance into
the urethra, at the spot where the urine first enters it, in its
passage outwards.

— The substance of the prostate, in which these ducts and
vesicles are placed, is not exactly understood. It is of a whitish
appearance, very dense, distensible and yet easily lacerated.
The superior face of the prostate is in contact with the anterior
ligaments of the bladder ; its inferior with the rectum to which
it adheres. It is overlapped by the rectum upon the sides
when the latter is distended with feculent matter ; laterally it
corresponds to the levator ani muscles ; by its hase, it corres-
ponds to the neck of the bladder ; and by its apex or anterior
extremity to the membranous portion of the urethra. Its dis-
tance from the skin of the perineum, measuring from a point an
inch in front of the anus, varies, according to Dupuytren, from
two to three inches and a half, as the subject is thin or fat.
— The prostate belong to the urethra, and not to the bladder
as students generally suppose. The urethra passes through it
near the centre, and this portion of it is called the prostatic
portion of the urethra. The prostate gland is about an inch in

* Section of the prostate gland magnified. — a, a, The two lobes separated, b,
Excretory ducts. — f.

VOL. II. 14

158 C0WPER*9 GLANDS.

length, measured in the middle line, and an inch and a half ira
breadth at its base or posterior part.

Cowper^s Glands,

■ — Or, as they are sometimes called, the little prostate glands,
are placed immediately behind the bulb of the urethra, between
the two layers of the triangular ligament, yet to be described.
Their ducts are about an inch in length, run under the mucous
membrane of the urethra, and open obliquely into the canal
about an inch in advance of the glands. The size of the
glands is usually about that of a garden pea (see fig. 164*) ;
sometimes they are much larger. I have succeeded in two or

Fig. 164.f three instances in distending them with mer-

, cury from their ducts. Their structure and

/r>.i^-^ office is the same as that of the prostate, (see

^{'•^ '"' '^a fig. 163); sometimes they are entirely deficient.

^^^v.^;;^/ One or more small glands of a similar descrip-
tion, have been discovered by Littre in front of those of
Cowper, near the angle of union of the crura penis. They
have been called the glands of Littre, but are rarely seen.
Cowper's glands are placed within the circle formed by the
ejaculator seminis muscles, the contraction of which will assist
in discharging into the urethra the mucus they secrete. In
some of the inferior animals, they are vesicular, and have been
mistaken for another pair of vesicnia seminales ; in these cases
however, the parts may always be distinguished from one
another ; the vesiculse seminales are distended with fluid only at
the epoch of rut ; Cowper's glands are always filled with an
opaline starch-like mucus. —

Of the Penis.

The penis, when detached from the bladdel", and the bones,
to which it is connected, and divested of the skin which covers
it, is an oblong body, which is rounded at one extremity, and
bifurcated at the other.

* Fig. 164, is a representation of Cowper's gland, cut open, showing its
similarity of structure with the prostate gland. —
I a, a, Cowper's gland divided, b, Excretory duct. —

THE PENIS. 159

It is composed of three parts, namely, two oblong bodies,
called Corpora Cavernosa, which, at their commencement,
form the bifurcated portions, and then unite to compose the
body of the organ ; and a third part, of a spongy texture,
which is connected to these bodies where they unite to each
other, on the under side, and continues attached to them during
the whole extent of their union, terminating in an expanded
head which covers the anterior extremities of the corpora caver-
nosa. The urethra passes from the neck of the bladder, on the
under side of the penis, fo its anterior extremity, invested by
this third body, which is therefore called Corpus Spongiosum
Urethra.

The two bifurcated extremities are attached each of them to
one of the crura of the pubis and ischium ; they unite to form
the body of the penis immediately anterior to the symphysis
pubis, to which the lower part of it is also attached ; so that the
penis is firmly connected to the middle of the anterior part of
the pelvis. The urethra proceeds from the neck of the bladder,
between the crura of the ischium and pubis and the crura of the
penis, to join the body of the penis, at its commencement, and
near this place its connexion with the corpus spongiosum begins ;
so that there is a small portion of the urethra between the neck
of the bladder, and the commencement of the corpus spongio-
sum, which is not covered by the corpus spongiosum. This is
called the membranous part of the urethra.

The penis therefore consists of two oblong bodies of a cellu-
lar structure, which originate separately, but unite together to
form it ; and of the urethra, which joins these bodies immedi-
ately after their union, and is invested by a spongy covering,
which by its expansion forms the anterior extremity not only of
the urethra, but of the whole penis. These three bodies, thus
arranged and connected, are covered by cellular membrane and
skin in a manner to be hereafter described.

The Corpora Cavernosa,
Which compose the body of the penis, are two irregular
cylinders, that are formed by a thick dense elastic membrane,

160 CELLS OF THE CORPORA CAVERNOSA.

of a whitish ligamentous appearance and great firmness. They
are filled with a substance of a cellular structure, which is occa-
sionally distended with blood. The crura of these cylindrical
bodies, which are attached to the crura of the ischium and
pubis, are small and pointed at the commencement, and are
united to the periosteum of the bones. In their progress up-
wards they enlarge, and at the symphysis of the pubis they
unite so as to form an oblong body, which retains the appear-
ance of a union of two cylinders applied to each other length-
ways ; for above, there is a superficial groove passing in that
direction, which is occupied by a large vein : and below there
is a much deeper groove, in which the urethra is placed. Be-
tween these grooves is a septum which divides one side of the
penis from the other. It appears to proceed from the strong
membrane which forms the penis, and is composed of bundles
of fibres, which pass from one groove of the penis to the other,
with many intervals between them, through which blood or in-
jection passes very freely. Sometimes these bundles of fibres,
with their intervals, are so regularly arranged, that they have
been compared to the teeth of a comb. This septum extends
from the union of the two crura to their termination.

— It is called the Septum pectiniforme ; the internal between
its bundles of dense cellular fibres, become so great and so
numerous in the anterior half, that it ceases to divide the penis
into two corpora cavernosa. Anatomists now consider the cor-
pus cavernosum as one body imperfectly divided by the septum.
It is a distinction, however, without much value. —

Each of these cylinders is penetrated by the main branch of
the pubic artery, which is about equal in size to a crow's quill.
These arteries enter the corpora cavernosa near their union, and
continue through their whole extent, sending off branches in
their course ; the turgescence and erection of the penis is un-
questionably produced by the blood which flows through these
vessels into the penis.

The interior structure of the penis, when examined in the
recent subject, is of a soft spongy nature, and seems stained
with blood. If any fluid be injected through the arteries this

THE URETHRA. 161

substance appears cellular, and may be completely distended
by it. When air is injected, and the structure becomes dry,
the penis may be laid open ; the cellular structure then appears
as if formed by a number of lamina and of filaments, which
proceed from one part of the internal surface of the penis to
another, and form irregular cells. It has been compared to the
lattice-work in the interior of bones; and it is suggested by M.
Roux, that the fibres of which the structure consists resemble
those of the strong elastic coat of the penis.* If these cells are
filled with colored wax, injected by the artery, and the animal
substance is then destroyed by placing the preparation in a
corroding liquor, the wax which remains shows that the
membranes forming the cells are very thin.

These cells communicate freely with each other ; and, there-
fore, if a pipe be passed through the strong coat of the penis,
the whole of them can be filled from it by the ordinary process
of injection.

The Urethra

Is a membranous canal which extends from the neck of the
bladder to the orifice at the extremity of the penis ; and for a
very great part of its length is invested by a spongy structure,
called the corpus spongiosum urethrae. It proceeds from the
neck of the bladder along the upper part of the prostate ; from
the prostate it continues between the crura of the penis until
their junction : it then occupies the great groove formed by the
corpora cavernosa on the lower side of the penis, and continues
to the orifice above mentioned. At a small distance from the
prostate gland the spongy substance which invests it com-
mences, and continues to its termination. After this spongy
substance has arrived at the termination of the corpora

* Mr. John Hunter says on this subject, " That the cells of the corpom ca-
vernosa are muscular, although no such appearance is to be observed in men :
for the penis in erection is not at all times equally distended. The penis, in a
cold day is not so large in erection as in a warm one : which probably arises
from a kind of spasm, that could not act if it were not muscular."

In the horse, the parts composing the cells of the penis appear evidently mus-
cular to the eye, and in a horse just killed, they contract upon being stimulated

— H,

14*

162 THE CORPUS SPONGIOSUM URETHRJE.

cavernosa, it expands and forms a body of a particular figure
which covers the extremities of the corpora cavernosa, and is
denominated the Glaus Penis.

The Corpus Spongiosum begins at the distance of eight or
ten lines from the anterior part of the prostate. It is much
larger at its commencement than at any other part except the
glans, and this enlarged part is called the Bulb. It surrounds
the whole of the urethra, and, with the exception of the
bulb and the glans penis, is of a cylindrical figure. It is formed
by a membrane which has some resemblance to the coat of the
penis, but is much thinner, and by a peculiar spongy substance,
which occupies the space between the internal surface of this
membrane and the external surface of the canal of the urethra.
The membrane and the spongy substance, form a coat to the
urethra, which, with the exception of the enlargement before
mentioned, is about one line thick. After this spongy substance
has arrived at the termination, its coat adheres firmly to the
coat of the penis.

The Bulb, or first enlargement of the corpus spongiosum, is
oblong, and rather oval in form ; it is marked by a longitudinal
depression in the middle, which is very superficial. It consists
entirely of the spongy substance above mentioned.

The Glans Penis is also composed of the same spongy sub-
stance, but the coat which covers it is more thin and delicate
than that of the other parts of the urethra. The lower surface
of the glans is fitted to the extremities of the corpora cavernosa,
but it is broader than the corpora cavernosa, and therefore pro-
jects over them on the upper and lateral parts of the surface
of the penis. The edge of the prominent part is regularly
rounded, and is denominated the Corona Glandis.

—The contracted portion immediately behind the corona, is
called the collum or neck. —

Several small arteries pass to this spongy structure. The
pudic artery, as it passes on each side to the corpora cavernosa,
sends a branch to the bulb of the urethra. The same vessel,
in the substance of the penis, also sends branches to the ure-
thra ; and the artery on the back of the penis terminates in small
tranches, which penetrate the substance of the glans.

THE CORPUS SPONGIOSUM.

163

By these vessels blood is carried to the spongy substance of
the urethra, which is occasionally distended in the same man-
ner that the cavernous bodies of the penis are distended during
the erection of that organ. But the cellular structure of this
organ is not so unequivocal as that of the corpora cavernosa ;

Fe>. 165.*

* A longitudinal section of the bladder, prostate gland, and penis, showing
the urethra. 1. The urachus attached to the upper part of the fundus of the
bladder. 2. The recto-vesical fold of peritoneum, at its point of reflection from
the base of the bladder, upon the anterior surface of the rectum. 3. The ope-
ning of the right ureter. 4. A slight ridge, formed by the muscle of the ureter,
and extending from the termination of the ureter to the commencement of
the urethra. This ridge forms the lateral boundary of the trigonum vesicae. 5.
The commencement of the urethra ; the elevation of mucous membrane imme-
diately behind the figure is the uvula vesicae. The constriction of the bladder at
this point is the neck of the bladder. 6. The prostatic portion of the urethra.
7, 7. The prostate gland ; the difference of thickness of the gland, above and
below the urethra, is shown. 8. The isthmus, or third lobe of the prostate ;
immediately beneath which the ejaculatory duct is seen passing. 9. The right
vesicula seminalis ; the vas deferens is seen to be cut short off, close to its
junction with the ejaculatory duct. 10. The membranous portion of the urethra.
11. Cowper's gland of the right side, with its duct. 12. The bulbous portion
of the urethra ; throughout the whole length of the urethra of the corpus spongio-
sum, numerous lacunae are seen. 13. The fossa navicularis. 14. The corpus ca-
vernosum, cut somewhat obliquely to the right side,near its lower part. The char-
acter of the venous-cellular texture is well shown. 15. The right crus penis. 16.
Near the upper part of the corpus cavernosum, the section has fallen a little to the
left of the middle line ; a portion of the septum pectiniforme is consequently seen.
This- figure also indicates the thickness of the fibrous investment of the corpus
cavernosum, and its abrupt termination at the base of ( 17) the glans penis. 18.
The lower segment of the glans. 19. The meatus urinarius. 20. The corpus
spongiosum. 21. The bulb of the corpus spongiosum.

164 INTERNAL OR MUCOUS COAT OF THE URETHRA.

for if it be injected with colored wax, and corroded in the
usual manner, the injected matter will exhibit an appearance
which has the strongest resemblance to a convoluted vessel,
like the vas deferens in the epididymis.*

The Canal of the Urethra,

Which conveys the urine from the bladder, is a very impor-
tant part of the urinary organs. It consists of a vascular mem-
brane with a smooth surface, which is perforated by the orifices
of many mucous follicles, some of which are of considerable
size. It is extremely sensible, and has so much power of con-
traction, that some persons have supposed muscular fibres to
exist in its structure.

It is differently circumstanced in different parts of its course.
While surrounded with the prostate it adheres firmly to that
body, seeming to be supported by it ; and here its diameter is
larger than it is farther forward. On the lower or posterior
side of this portion of the urethra, is an oblong eminence, called
Verumontamim, or Caput Gallinaginis, which commences at
the orifice of the urethra, and continues throughout the whole
portion that is surrounded by the prostate gland, terminating
at the point of that body. The posterior extremity of this
tubercle begins abruptly, and soon becomes thick and large ;
anteriorly it gradually diminishes to a line, which is sometimes
perceptible for a considerable distance in the urethra, in a
straight forward direction. In the upper edge or top of this
body is a groove, which is produced by a mucous follicle ; on
the lateral surfaces, anterior to the middle, are the orifices of
the common ducts of the vesiculae seminalis, and vasa deferentia,
(see page 154,) which are sufficiently large to receive a
thick bristle. Near these, on each side, are five or six smaller
orifices of the excretory ducts of the prostate gland. At the
distance of an inch before the extremity of the bulb of the

* Mr. Hunter says, " that the corpus spongiosum urethrse and glans penis
are not spongy or cellular, but made up of a plexus of veins. This structui:p is
discernible in the human subject ; but is much more distinctly seen in many
animals, as the horse,"' &c. — h.

MUCOUS FOLLICLES OF THE URETHRA. 165

urethra, in the lining membrane, are the openings of two ducts,
one on each side, that lead to small glandular bodies called
Cowper's glands, which are situated on each side of the urethra
below the bulb, but are covered by the acceleratores urinse
muscles.

The diameter of the urethra lessens after it leaves the prostate.
That portion of the canal which is between this gland and the
bulb, without investment, and therefore called the membranous
part, is the smallest in diameter.

After it is invested with the spongy substance, it has a small
enlargement, and then continues nearly of one size, until it
arrives near the glans penis, when it again enlarges and alters
its form, being no longer cylindrical, but flattened. Its broad
surfaces have now a lateral aspect.

From the bulb of the corpus spongiosum to this last en-
largement, the appearance of the inner surface of the urethra
is uniform. The membrane is thin and delicate, and in a healthy
subject, who has been free from disease of these parts, is of a
whitish color; but blood-vessels are very perceptible in it.
When it is relaxed, it appears to be thrown into longitudinal
wrinkles ; but it admits of considerable extension ; being some-
what elastic : when extended, its surface appears smooth, as if
it were covered with an epithelium. Mr. Shaw, of London,
has described a set of vessels immediately below the internal
membrane of the urethra, which, when empty, are very similar
in appearance to muscular fibres. He says he has discovered
that these vessels form an internal spongy body, which passes
down to the membranous part of the urethra, and forms even
a small bulb there. His preparation with a quicksilver injec-
tion of the part is certainly a very satisfactory proof of its ex-
istence.* Throughout the whole extent of this part of the
urethra, are the orifices of a great many mucous ducts or
sinuses, which pass obliquely backwards. Many of these are
so small that they cannot be penetrated by a bristle, or probe
of that size ; but some are larger. It has not been observed
that any glandular body immediately surrounds them, although
they secrete the mucus with which the urethra is lubricated.
♦ See Med. Chirurg. Transactions of London, vol. x.

166 SITUATION OF THE MUbCLES.

On the lower side of the urethra, near the commencement of
the glans penis, there is one or more of them, so large that their
orifices sometimes admit the point of a small bougie."*

These organs when inflamed, secrete the puriform discharge
which takes place in gonorrhoea. — In a natural state they pro-
duce the mucus which is constantly spread over the surface of
the urethra, to defend it from the acrimony of the urine, and
which passes away with that fluid un perceived.

The surface of the urethra is endued with great sensibility,
and is therefore liable to great irritation from contact with any
rough body or any acrid substance. Irritation, thus excited,
induces a state of contraction, which is particularly remarkable,
as no muscular fibres are to be seen in its structure. When a
bougie has been passed into the urethra for a considerable dis-
tance, if it cannot proceed the whole way, it sometimes happens
that the instrument will be discharged by a steady uniform
motion, which seems to proceed from a progressive contraction
of the urethra, beginning very low down. At particular times,
after the urethra has been much irritated, it will not receive a
bougie, although at other times a bougie of equal size may be
passed to the bladder without opposition. This cannot depend
upon that elasticity which was noticed before.f

Upon the two crura of the penis, or the beginning of the
corpora cavernosa, are fixed the muscles called Erectores
Penis, which are described in the first volume.j; These mus-
cles cover the crura of the penis from their origin to the junction,
and not only compress them, but also influence the motion of
the penis when it is distended.

The bulb of the urethra is covered by a muscular coat, called
the Accelerator Urina, which has the effect of driving forwards

* They were discovered by Plazzoni, of Padua, in 1621. Their number,
according to Loder, amounts to about 65. See his plates. — h.

f Sir Everard Home, whose professional opinions are of great weight, has
lately described in the Transactions of the Royal Society, the appearance of
the lining membrane of the urethra, when viewed through a microscope of
great powers. From this paper it seems that he is fully convinced of its
muscular structure. — n.

t See description of " Muscles about the Male Organs of Generation,"
vol. 1, p. 306.

SITUATION OF THE MUSCLES. 167

any fluid contained in the cavity of the urethra, and also of
giving the same direction to the blood in that part of the corpus
spongiosum. There is also the Transversus Perinei on each
side, that passes transversely from the tuberosity of the ischium
to the bulb of the urethra. — Finally, the lower part of the
sphincter ani muscle, which is nearly elliptical in form, is in-
serted by its anterior point into the muscular covering of the
bulb of the urethra. Upon removing the integuments, these
muscles are in view ; and the course of the urethra from the
bladder is concealed, particularly by the anterior point of the
sphincter ani. When the sphincter anI is dissected away from
its anterior connexions, and the cellular and adipose substance,
which is sometimes very abundant, is also removed, the lower
surface of the membranous part of the urethra may be brought
into view, as it proceeds from the. prostate gland to the bulb of
the corpus spongiosum.*

When the accelerator urinas is removed from the bulb of the
urethra, there will appear two bodies, which have some resem-
blance to flattened peas. They lie one on each side of the
urethra, in contact or nearly so with its bulb, and from each
gland proceeds an excretory duct of an inch and a quarter in
length between the corpus spongiosum and tlie lining membrane
of the canal of the urethra, and opens into the latter. Its orifice
is found with some difficulty, but is large enough to admit a bris-
tle. These are Cowper's glands.f

The penis is connected to the symphysis pubis by a ligamen-
tous substance, which proceeds from the back or upper surface
of the organ to the anterior part of the symphysis, and connects
these parts firmly to each other, called ligamentum suspenso-
rium penis.

* The natural situation of the membranous part of the urethra, and of the
prostate gland, as well as their relative position with respect to the sphincter
ani, rectum, &c., can be best studied by a lateral view of the contents of the
pelvis ; which is to be obtained by removing carefully one of the ossa innomi-
nata, and dissecting the parts which were enclosed by it.

f These glands were discovered by Mery, in 1684, and described by Cowper,
in 1699. A third gland, smaller than the preceding, connected with the curve
of the urethra under the symphysis pubis, was discovered by Cowper, and
Morgagni speaks of having observed a fourth. — h.

168 LENGTH OF THE URETHRA.

Thus constructed, of the corpora cavernosa and the urethra
with its corpus spongiosum, and attached to the pelvis as above
mentioned, the penis is invested with its integuments in the fol-
lowing manner.

' — The entire length of the urethral canal from its commence-
ment at the back part of the prostate gland that is at the neck
of the bladder, to its external orifice in the glans penis, varies
in different subjects when distended or gently drawn out, from
eight to ten inches. The difference in length in different indi-
viduals is found to depend upon the greater or less development
of the penis from the bulb of the urethra outwards ; the length
of the membranous and prostatic portions being nearly the same
in all adult subjects. The membranous portion of the urethra
extends from the bulb to the anterior margin of the prostate, and
is about three quarters of an inch long; it is rather longer on its
upper than its lower surface, in consequence of the extension of
the pendulous portion of the bulb backwards. In place of the
spongy portion, it is covered on its outer surface with a thin
layer of pale cellulo-muscular fibres like that forming the neck of
the bladder (see page 131,) with which it is continuous.*

* Mr. James "Wilson described a muscle, designated commonly as the muscle
of Wilson, (see vol. 1, p. 338,) situated one upon each side of the membranous
portion of the urethra, called the musculus compressor urethras or pubo-urethra-
lis. It is oblong, quadrilateral, and flattened from without inwards. It arises
from a short tendon on the back part of the pubis, near the symphysis. It in-
creases in size as it descends, embraces closely the membranous portion of the
urethra, and at the lower surface of the latter is closely connected with its fellow
of the opposite side, so that the two form as it were a muscular ring around
the urethra. In front it is usually connected with the posterior part of the
accelerator urinse muscle, and below it is connected to the levator ani. It ap-
pears to me to form a part of the latter muscle, and to act as a constrictor of
the urethra to the male and of the vagina in the female. A transverse fasciculus
belonging to this muscle was pointed out by Santorini to which the attention of
the profession has recently been called by Mr. Guthrie. Among English anato-
mists it is now known as the muscle of Guthrie. It arises on each side from
the crus ischii, and is inserted into the under part of the membranous portion
of the urethra, the perineal centre, and the point of the prostate. It embraces
Cowper's glands, and is connected with the lower part of Wilson's muscle.
These are voluntary muscles, according to Mailer, and are the principal agents
by which we exercise any voluntary control over the discharge of urine. When
spasmodically contracted, they compress the urethra, and often render the pass-
ing of a catheter along this portion of the canal impossible, till the spasm is
relaxed by medicinal means. — v.

LENGTH OF THE URETHRA. 169

— The prostatic portion of the canal is of the length of the
gland, and varies from fifteen to eighteen lines. It is conoidal
in its shape, the base of the cone being on the side of the blad-
der, and its narrowest part or apex continuous with the mem-
branous portion. In consequence of this shape, small calculi
frequently drop into it from the bladder, and sometimes imbed
themselves in the substance of the prostate gland. The direc-
tion of the prostatic and membranous portions of the urethra
is from above downwards and backwards, towards the neck
of the bladder, forming a curve, the concavity of which is
towards the pubis. The spongy or external portion of the
canal forms a curve in the opposite direction, so that the whole
canal in its undistended state, resembles somewhat in shape
the italic /. When the penis is drawn upwards and forwards,
both curves, as Amusat has shown, are nearly effaced,
and a straight instrument may, with facility, be passed into the
bladder. —

— Much difference of opinion exists among writers in reference
to the length of the urethral canal. According to Sabatier it is
from 10 to 12 inches long — Cloquet and Lisfrane 9 to 12 —
Amusat 7 to 8 — Civiale and Maloraigne about 6. Much of this
discrepency may be accounted for by the different modes of
admeasurement adopted — whether the urethra be measured on
the living subject by the means of a catheter, which gives the
actual length of the tube in the unexcited state of the organ ; or
after its removal from the body (when it becomes very disten-
sible,) and having been stretched out on a board. Measure-
ment by the former process, which gives the shorter length, is
the only one of value in practice. The genital organs of the
black in the opinions of most of American anatomists, are
more largely developed than those of the white.
— The following are the measurements of the urethra from
the neck of the bladder to the external orifice of the penis,
which I recently took from four patients in the Philadelphia
Hospital ; viz. four blacks and two mulattoes.

VOL. II. 15

Do.

5 ft. 5 inch

Do.

5 " 6 "

Mulatto,

6 " 1 "

Do.

6 " "

170 INTEGUMENTS OF THE PENIS.

— Negro — 6 feet 4 inches in height — length of urethra moderately
stretched on catheter 8^ inches, unstretched 1\ inches.

(( Q3 (( (( 7l

^4 '4

U Qi (( (( 7

^4

u 8 " " 62

(( Qi (( <( 71

"4 '4

A small negro boy of 9 " 4 " " 3|

Integuments of the Penis.

The glans penis, the structure of which has been already
described, is covered by a continuation of the skin which
appears altered in its texture so as to resemble in some respects
the skin of the lips, and in like manner is covered by a delicate
production of cuticle.

Around the corona of the glans, especially on its upper part,
there are whitish tubercles, glandula. Tysonii, which are of
different sizes in different persons, but always very small. The
skin adheres firmly to the whole extent of the corona of the
glans, and is very delicate in its structure, as it continues from
the glans upon the body of the penis ; but it gradually changes
so as to assume the appearance and structure of a common
skin, and continues in this state over the penis. The adhesion
of the skin to the ligamentous coat of the corpora cavernosa
also becomes more loose, owing to the quantity and texture of
the cellular substance which connects them. The skin, thus
connected to the penis, has commonly more length than that
organ, even in its extended state. In consequence of this greater
length, and of its adhering firmly around the corona glandis,
it necessarily forms a circular fold or plait, which varies in size
according to the length of the skin. This fold is generally
situated at the commencement of the firm attachment of the
skin to the body of the penis, or around the glans ; but it may
be formed any where upon the body of the penis by artificial
management.

This duplicature, or fold of the skin, when it takes place so
as to cover the glans, is called the Prepuce; and the skin,

INTEGUMENTS OF THE PENIS. 171

which is very tender and dehcate for some distance from the
glans, forms that surface of the prepuce which is in contact
with the glans when it covers that body.

There is also a small fold of the skin which is longitudinal in
its direction, that commences at the orifice of the urethra, and
extends backwards on the lower surface of the penis. It is
unvarying in its position, and is called Frenum.

It is a general observation, that adeps is not found in the
cellular substance which connects the skin to the body of the
penis ; but this cellular substance is distended with water in
some hydropic cases.

From the glands of Tyson, and from small follicles on each
side of the fraenum, is secreted an unctuous fluid, (^Smegma
preputii,) which when allowed to continue, becomes inspissa-
ted, and acquires a caseous consistence and color, as well as
a peculiar odor. It sometimes also acquires an acrimony which
produces inflammation on the surface with which it is in contact,
as well as the copious secretion of a puriform fluid.

The distribution of the pudic artery in the penis has already
been mentioned ; and a farther account of its origin and pro-
gress to its destination, will be found in the general account of
the arteries. Sometimes small branches of the external pudic
arteries, which originate from the femoral, are extended to the
penis ; and it has been asserted, that branches of the middle
haemorrhoidal artery have also been found there, but this does
not often occur.

The Veins of the penis are of two kinds ; those which origi-
nate in the corpora cavernosa, accompany the corresponding
branches of the pudic artery, but communicate more or less
with the plexus of veins on the lower and lateral part of the
bladder. There is also a great vein, which occupies the groove
on the back of the penis, between the corpora cavernosa, that
appears particularly appropriated to the corpus spongiosum
urethra ; for it originates in the glans penis, and receives
branches from the urethra as it proceeds backwards. There
are often two of these veins, one in the groove, and the other
more superficial: they generally unite near the root of the

172

PERINEAL FASCIA.

penis. The common trunk then passes between the body of
the penis and the symphysis pubis, and terminates in a plexus
of veins at the neck of the bladder, which is connected to the
plexus above mentioned on the lower and lateral parts of the
same viscus.

The Absorbent Vessels of the penis take two different direc-
tions on each side. Those which arise from the integuments
generally, unite so as to form a few trunks on the back of the
penis, which divide near the root of the organ, and proceed to
the glands of the groin. Those which originate from the inte-
rior parts of the penis, accompany the blood-vessels, and ter-
minate in the plexus of lymphatics in the pelvis.

It ought to be noted, that the superficial lymphatics gene-
rally enter the upper inguinal glands. — The deep-seated
lymphatics, which originate in the glans penis and the cavern-
ous structure, run with the cavernous artery of the penis,
directly into the pelvis. Hence in chancres of the glans, the
venereal poison may be introduced into the system without
traversing the glands of the groin. —

The Nerves of the penis are principally derived from the
lower sacral nerves, which unite in the plexus that forms the
great ischiatic. From these nerves a branch on each side ori-
ginates, which passes, like the pudic artery, between the sacro-
sciatic ligaments. In this course it divides into two branches,
one of which passes below to the muscles of the penis and
urethra, and to the contiguous parts ; and some of its branches
seem finally to terminate in the dartos : the other branch pro-
ceeds along the crura of the pubis and ischium, and passing
between the symphysis pubis and the body of the penis,
arrives at the upper surface or dorsum of the penis, along which
it continues on the outside of the veins to the glans, in which it
terminates. In this course it sends off several branches, some of
which terminate in the integuments of the penis.

Fascice of the Perineum.

[There are several fasciae and ligaments about the perineum,
which should be connected with the account of its viscera.

INFERIOR PERINEAL FASCIA, 173

Immediately beneatl\ the skin of the perineum is the Perineal
Fascia, a thin but stit>ng membrane, which extends from bone
to bone, occupying the space between the anus and the poste-
rior part of the scrotum. It is rather better seen in lean subjects
than in fat ones, for in the latter it is converted in part into adi-
pose membrane. When a rupture occurs in the posterior part
of the urethra, this fascia prevents the urine from showing itself
immediately in the perineum, and drives it into the cellular
structure of the scrotum.

Immediately beneath the perineal fascia are placed the
muscles ; when they are removed, the bulb of the urethra may
be seen very advantageously, extending in the middle of the
perineum almost to the anus. It is not loose and pendulous,
but is attached by its pelvic surface to the triangular ligament of
the urethra. This ligament is a septum between the perineum
and the pelvis, and connects itself to the pelvic or internal edges
of the rami of the pubis and ischium as far down as the organs
of the crura ^enis. It extends from the arch of the pubis to
the line mentioned, and fills up all the space between the bones
of the opposite sides. It consists of two lamina, and Cowper's
glands are placed between them. About an inch below the
symphysis pubis a perforation is made in this ligament for the
passage of the membranous part of the urethra.

Just below the symphysis pubis, between the two lamina of
the triangular ligament, is placed a much stronger ligament
called the pubic, which is about half an inch broad ; its lower
edge is thick and rounded.]

— There are three fasciae belonging to the region of the peri-
neum, exclusive of the pubic ligament just described, and the
common superficial or subcutaneous fascia which is here dense
and loaded usually with fatty matter.

— The three proper fasciae of the perineum, are named from
their relative position. 1st. The inferior perineal fascia,
described above simply as perineal fascia. 2d. The middle
perineal fascia, which from its shape is generally known as the
triangular ligament. — 3. The superior penneaZ/asaa, or pelvic
aponeurosis.

15*

174

MIDDLE PERINEAL FASCIA.

— 1. The Inferior perineal fascia, is somewhat of a triangular
shape, the narrowest portion being in front. It contains many
well marked transverse fibres, is attached to the rami of the
pubis and ischium of each side, and stretched across the inter-
Fig-. 166.*

vening space, covering in several genital muscles and the root
of the penis. Anteriorly it is connected with the dartos muscle
of the scrotum, and the investing fascia of the penis. Poste-
riorly it terminates in front of the anus, by being reflected under
the transversus perinei muscles so as to communicate with the
anterior layer of the middle perineal fascia.
— 2. The middle fascia of the perineum called besides, deep
fascia, triangular ligament of the urethra, and Comperes liga-
ment is also attached but more internally than the inferior to the
rami of the pubis and ischium of each side, and is also firmly

* The pubic arch with the attachments of the perineal fasciae. 1, 1, 1. The
superficial perineal fascia divided by a j^ shaped incision into three flaps ; the
lateral flaps are turned over the ramus of the os pubis and ischium at each
side, to which they are firmly attached. The posterior flap may be traced in
continuation with the middle perineal fascia. 2. The middle perineal fascia or
triangular ligament of the urethra. 3. The opening for the passage of the
membranous part of the urethra previous to its entering the bulb. 4. Two
projections of the anterior layer of the middle perineal fascia, corresponding
with Cowper's glands. —

TRIANGULAR LIGAMENT OF THE URETHRA. 175

Stretched Across the triangular space formed between these
bones. This ligament is vertical near the arch of the pubis,
and as far down as the bulb of the urethra, which is attached
to its front surface by cellular tissue. Below the bulb its
direction is obliquely backwards and downwards. This liga-
ment consists of two layers, an anterior and posterior, which
are nearly in contact below the arch of the pubis and separate
more widely at their inferior termination. Between the layers
are placed at the top — the sub-pubic ligament, a considerable
part of the membranous portion of the urethra which pierces
both lamina at the orifices left for it about an inch below the
symphysis, Cowper's glands found a little below this orifice,
the compressor urethra muscle, described page 168, and the
pudic vessels which run up on the sides, and send in their
branches between the lamina to supply the bulb. There
are two openings through these layers above, by which the venae
dorsales penis pass, upon the neck of the bladder so as to empty
the vesical plexus.

— Half an inchr below the orifice of the urethra is found the
lower boundary of this middle perineal or triangular ligament.
At this level the anterior layer is united under the transverse
perineal muscles with the lower edge of the inferior perineal
fascia and the posterior layer is reflected backwards to the
rectum, the extremity of which intestine it aids the anal fascia
in supporting. The posterior sends back besides, a funnel-
shaped process along the membranous portion of the urethra,
which covers the prostate gland and is continuous with the
recto-vesical fascia lately described by Mr. Tyrrel. The use of
this remarkable aponeurosis, is to support the bulb and mem-
branous portions of the urethra, and form a strong septum of
defence to the outlet of the pelvis. The rigidity and tenseness
of this fascia around the urethral passage, which has its fixed
curve at this point, constitutes an obstacle to the introduction of
the catheter, when its point deviates from the direction of the
canal. In the female the triangular ligament is perforated by
the passage of the vagina, as well as by the urethra.

176

SUPERIOR PERINEAL FASCIA.

— 3. The superior perineal fascia or pelvic aponeurosis,
is but an extension of the fascia covering the iliacus internus
muscle, {fascia iliaca) that passes beneath the external iliac
vessels, turns over the brim of the pelvis to which it becomes

Fig. 167.*

attached, and then dips down to line the sides and bottom
of the pelvic cavity. The rectum and bladder having tubular
outlets which open inferiorly, the fascia cannot pass as a level
sheet across the bottom of the cavity ; but where it encounters
the rectum, and the bladder with its adherent prostate, it
mounts up upon the sides of these organs, giving them an
aponeurotic coat. Hence the layer at the bottom of the pelvic
cavity which constitutes the superior perineal fascia, is some-

* A transverse section of the pelvis, showing the distribution of the pelvic
fascia. 1. The bladder. 2. The vesiculse seminales divided across. 3. The
rectum. 4. The iliac fascia covering in the iliacus and psoas muscles (5) ; and
foriuing a sheath for the external iliac vessels (G). 7. The anterior crural nerve
excluded from the sheath. 8. The pelvic fascia. 9. Its ascending layer, form-
ing the lateral ligament of the bladder of one side, and a sheath to the vesical
plexus of veins. 10. The recto-vesical fascia of Mr. Tyrrel formed by the
middle layer. 11. The inferior layer surrounding the rectum and meeting at
the middle line with the fascia of the opposite side. 12. The levator ani mus-
cle. 13. The obturator internus muscle, covered in by the obturator fascia,
which also forms a sheath for the internal pudic vessels and nerve (14). 15.
The layer of fascia which invests the under surface of the levator ani muscle,
Che anal fascia.

PELVIC APONEUROSIS. 177

times called the recto-vesical fascia or recto-vesical aponeuro-
sis. The reflection of this fascia about the rectum, is consid-
ered by Mr. Tyrrel as consisting of two layers. One which he
calls the middle layer (see fig. 167,) passes between the base of
the bladder, and the anterior face of the rectum. The other
called by him the inferior layer, passes behind the rectum and
with the layer of the opposite side completely surrounds this
intestine. To the middle layer he has proposed to restrict the
term recto-vesical fascia ; but this name, it appears to me is too
commonly used in the more extended sense, to admit of this
limitation.

— As the fascia of each side passes from the two pubic bones to
the bladder, there is formed in front two ligamentous bands, with
a small fascia between them, lined by the peritoneum. These
bands constitute the anterior ligaments of the bladder.
— Posteriorly tjiis fascia or aponeurosis is reflected backwards
from each side upon the front surface of the sacrum, where it
becomes thin and is finally lost. It passes in front of the sciatic
plexus of nerves, over which it sometimes forms a bow.
— Another bow formed by this aponeurosis has been carefully
described by Mr. Colles, the concavity of which looks up-
wards. The anterior end of this bow is fastened to the pubis
above the thyroid foramen ; the posterior to the ischium above
its spine. This bow is called from its shape semi-lunar. At
this point the pelvic aponeurosis splits into two layers, the inter-
nal one of which, or \\\e pelvic, has alone been described. The
other or outer one, is called the obturator, and passes directly
downwards, as seen in fig. 167, lining the inner surface of the
obturator internus muscle, and forming a sheath for the internal
pudic vessels and nerves. Between these two fascia from which
it partly has its origin, lies the levator ani muscle. The obtu-
rator, and levator ani muscles diverge below from each other,
forming thereby a. fossa opening downwards filled up with very
vascular fat, called the ischio-rectal fossa. At the point of di-
vergence, a thin process is sent off from the obturator fascia,
which lines the lower portion of the levator ani muscle, and is
continued on to the anus, this is sometimes called the anal fascia.

178 GENERAL ANATOMY OF ERECTILE TISSUE.

After an examination of the relative situation of the muscles and blood-vessels
of the male organs of generation, there appears reason to doubt, whether the
erection of the penis can be referred to pressure upon the veins which return
from that organ. Albinus has written on this subject. See Academicarutn
Annotationum, lib. ii. caput xviii. Haller has also considered it, and stated
the opinions of several anatomists, in his Elemenia Physiologige, torn. vii.
page 555.

The manner in which the urine is confined in the bladder does not appear to be
clearly understood. The connexion of the neck of the bladder with the pros-
tate, and the appearance of the contiguous parts of the bladder, do not ren-
der it probable that these parts act like a sphincter. The late J. Hunter, who
paid great attention to the functions of these organs, was very decided in his
opinion that the contraction of the urethra produced the effect of a sphincter
of the bladder. He has published some very ingenious observations respect-
ing the manner in which urine is discharged from the bladder, in his Treatise
on the Venereal Disease, part iii. chapter ix.

Mr. Hunter also long since asserted, that the vascular convoluted appearance of
the corpus spongiosum urethrse was more distinct in the horse than the man.
In the fifth volume of Le9on's d' Anatomic Comparee of Cuvier, the very
learned and ingenious author confirms the declaration of Hunter, respecting
the vascular convolutions of the corpus spongiosum of the horse. He states,
that the corpora cavernosa of the penis of the elephant appear to be filled ia
a great degree with the ramifications of veins which communicate with each
other by such large and frequent anastomoses, that they have a cellular ap-
pearance. A similar structure exists in the horse, camel, bullock, deer, &:c. ;
and |in them all these communicating branches can be distinguished from
those which extend the whole length of the penis.

The corpus spongiosum urethrae, according to M. Cuvier, is constructed in a
similar manner. From these facts he is induced to believe that this structure
pervades the whole class of mammalia.

General Anatoray of Erectile Tissue.

— The term erectile tissue, tela erectilis, was first adopted
by Dupiiytren and Rullier, to indicate various parts which are
principally composed of blood-vessels, intimately interwoven
with nerves, and which, under various causes of excitement,
mechanical or sensorial, are rendered turgid and prominent,
or thrown into a state of erection by a sudden influx of blood.
This system includes the corpus cavernosum penis, corpus
spongiosum urethrae, clitoris, nymphae, plexus retiformis
vaginae, nipples, cutaneous papillae, mucous villi, red borders
of the lips, and, according to Harrison, the seminal tubercle or
caput gallinaginis. It is supposed by some to exist in the iris,
and Beclard is disposed to include in this tissue the spleen. It

GENERAL ANATOMY OF ERECTILE TISSUE.

179

is seen also in other positions in the inferior animals, as in the
wattles of the turkey, and tongue of the chameleon. It is
developed also accidentally in different parts of the body, as in
Fig. 168.* erectile tumors, (aneurisms from

anastomosis,) and in fungus hae-
matodes. In some of the organs
it is enclosed in a fibrous sheath^
which limits the extent of the
expansion and detern)ines its
form. Its development, how-
ever, is found more perfect in
some organs than the rest, and it
is most so in the corpus caver-
nosum penis, and corpus spon-
giosum urethree. In these parts
it has principally been made the
subject of investigation. The
commonly received opinion, and
which is kept up by the appear-
ance which anatomical prepara-
tions present when the common
cellular tissue of the parts is
filled with wax to exhibit their
general form, is this ; that the
erectile tissue consists of loose
elastic tissue divided into innu-
merable cells, into which, during
erection, blood is poured by the
arteries and taken up subse-
quently by the veins. Such was
the opinion of Ruysch, Haller,
and Bichat. Vesalius, Mascagni and Hunter, were of the opin-
ion that the tissue was made up of a multitude of arteries and
veins, the latter predominating greatly in number, closely inter-
woven, and resting upon the cells ;* which are formed by pro-
cesses or trabecule sent inwards from the general investing sheath

* See Erectile Tissue, Diet. Des Sciences Medicales, by Dupuytren and JRul-
ller. — p.

180 GENERAL ANATOMY OF ERECTILE TISSUE.

of the parts (involucrum). These divide the interior into cells,
like the septae which divide the cavity of an orange, and form a
sort of scaffolding for the support of the vessels. This opinion
has been supported by Cuvier, Tiedemann, Beclard and Weber,
who assert that a structure corresponding to it is discernible in
man, and is particularly obvious in the horse and other large
animals. The annexed cut from Moreschi, fig. 168, shows the
congeries of vessels as they exist in the injected state in the
glans penis, which are principally veins, and are characterized
by their number tenuity and softness, and which empty into the
superficial veins of the penis.

— Professor Miiller has recently discovered in the structure of
the corpus cavernosum penis, two sets of arteries forming rami-
fications from the common trunk — the arteria profunda. One
of these consists of the ordinary nutritious arteries of the part,
which ramify over the cells and terminate in the capil-
lary veins, and through which, in the unexcited state, all
the blood flows that is conveyed by the profunda. The
Fig. 169. other sets he calls the arteria helicince, see
\%U ^o- 16^5 which is a magnified representa-

■''^Tw^'^ tion of part of the profunda with its helicine
^t^fi 'h^^ branches. These are so named from their
7-^^^ 4 ^)^ resemblance to the tendrils of the vine ; they
are much shorter, however, m proportion to
their thickness, than the comparison would
seem to indicate. These arteries become
dilated during the state of erection, and
receive all the blood which is imported
by the profunda in increased quantities
during the period of excitement. They may be seen with the
lens or even with the naked eye, in the back part of the corpus
cavernosum penis, when the profunda has been injected with
colored size, the corpus cavernosum subsequently slit open,
and all the injection which has escaped into the cells, carefully
washed away. These branches from the profunda are short,
being about a line in length and a fifth of a millimetre* in diam-

* A millimetre equals the 0.03937 of an English inch.

GENERAL ANATOMY OF ERECTILE TISSUE. 181

eter, and are of the same size whether they are derived from
the larger branches or the finest twigs.

— The arteriae heHcinse, sometimes branch off singly ; sometimes
in little bundles from three to ten in number, in which case
they originate by a common trunk. They project constantly
into the cells of the spongy substance, which Miiller considers
venous cavities, and either terminate abruptly, or swell out
into a club-like process without again subdividing. These
vessels when they project into the venous cavities, according to
Miiller, are not entirely naked, but are covered by a delicate
membrane, which, under the microscope, appears granular,
and when the arteries form a bundle like a skein of thread, the
whole bundle is covered by a gauze-like membrane. Miiller
considers this membrane as performing an important part
in the phenomena of erection. The arteries have neither
on their sides or extremities, any openings discoverable
with the microscope ; and when the blood, as is probable,
escapes from them in large quantities into the venous cells
during erection, it must either pass through invisible open-
ings or by orifices which become enlarged by the dilatation of
the arteries. These helicine arteries appear to have been seen
by Weber, and figured in his plates, though not under that par-
ticular name, (V'ide Tab. xxvi. figs, xxvii. xxviii.)*
— The discovery of these vessels by Miiller, though they do
not by any means fully explain to us the phenomena of erec-
tibility, goes far towards reconciling the two conflicting opinions
entertained upon this subject. That the cells formed by the
septae of the corpus cavernosum and spongiosum penis, are
lined with the lining membrane and continuous with the cavity
of the veins, there can, I think, be little doubt. For with the
injecting pipe plunged at random in the cells of these parts, we
invariably succeed in filling the superficial veins of the penis ;
and by inserting a pipe in the vena magna ipsius penis, we
are equally successful in distending with injecting matter,
the spongy cells. In these cells ramify the helicine arteries of

* Mullet's Archives, or London Medical Gazette, No. 423.
VOL. II. 16 •"

182 COMPRESSOR VEN« DORSALIS MUSCLE.

Miiller, by which the blood is conveyed with which the cells
are distended as by an injection throughout the arteries, during
erection.

— How far any coarctation or compression of the superficial
veins at the root of the veins may assist this accumulation of
blood in the cells, or whether it takes place at all, is not
known. Two muscles have been lately described by Mr.
Houston* under the name of compressores vence dorsalis penis ;
said to possess this office. They arise on each side from the
ramus of the pubis above the erector penis muscle, expand into
a thin layer, pass upward and forward and unite in a common
tendinous band over the dorsal vein. They are separated from
the muscle of Wilson by laying in front of the anterior layer
of the triangular ligament ; and the crura of the penis intervenes
between them and the erector penis muscle. — 1 consider it
doubtful however from my own dissections, whether these mus-
cles are any thing more than the anterior termination of the
accelerator urinae muscles which may be traced forwards on the
sides and dorsum of the penis to the suspensory ligament of the
organ. The veins which they are said to compress are more-
over the superficial, and not the deep seated which alone com-
municate with the cells of the corpus cavernosum. —

* Dublin Hospital Reports, vol, 5.

FEMALE ORGANS OF GENERATION. 183

CHAPTER VI.

OF THE FEMALE ORGANS OF GENERATION.

The female organs of generation consist of the Uterus and
Ovaries, with their appendages ; and of the Vagina, with the
structure which surrounds its external orifice. The uterus is
situated in the pelvis, between the bladder and rectum ; and
the ovaries are on each side of it. The vagina is a very
large membranous canal, which passes from the uterus down-
wards and forwards, also between the bladder and rectum, and
opens externally.

Connected with the orifice of the vagina are several bodies,
which are called the external parts of generation, in order to
distinguish them from the uterus and ovaries, and their
appendages, and also from the canal of the vagina ; which are
called the internal parts.

The bladder of urine lies above and in contact with the
vagina : the urethra is also intimately connected with it. The
description of the bladder and urethra is therefore placed at the
end of this chapter.

Of the External parts of Generation.

— All the external parts of generation are included under the
general term of vulva. They consist of the mons veneris, the
labia externa, the fourchette, the fossa navicularis, the clitoris,
the nymphae, and the hymen. —

The adipose membrane, immediately anterior to the sym-
physis pubis, and on each side of it, forms a considerable
prominence in females, which, at the age of puberty, is covered
with hair, as in males. This prominence is denominated the
Mons Veneris.

184 LABIA EXTERNA. CLITORIS.

The exterior orifice commences immediately below this.
On each side of this orifice is a prominence continued from the
mons veneris, which is largest above, and gradually diminishes
as it descends. These prominences have some hair upon them.
They are called the Lahia Externa. Their junction below is
denominated the Fourchette. — The fourchette or frenulum
vulva, is a delicate duplicature of the lining membrane, which
forms the posterior commissure of the labia externa. In the
virgin state it contracts the opening into the vagina, and behind
it that canal forms a little depression or pouch. It is usually
ruptured or effaced during the first act of parturition. — The
space between the place of their junction and the anus is rather
more than an inch in extent, and is denominated the Perineum.

— The perineal space between the vagina and rectum,
extends upwards for about three inches, and terminates in a
point ; it is filled chiefly with cellular and adipose matter,
through which many nerves and blood-vessels run, and is called
the perineal triangle. This shares in the distention of the
vagina during parturition, so that in the passage of the head of
the child, there appears only interposed between it and the
cavity of the rectum, a thin membranous layer. —

As the skin which forms the labia is continued internally, it
becomes more thin and soft, and is covered by a more delicate
cuticle. It is also more or less florid, and secretes a peculiar
mucus.

In the upper angle, formed by the labia externa, is the upper
extremity and glans of the clitoris.

The Clitoris is a body which has a very strong resemblance
to the penis, but there is no urethra attached to it. It has two
crura of considerable length, which originate, like those of the
penis, from the crura of the pubis and ischium, and unite at the
symphysis of the pubis so as to form a body, which is not
much more than an inch in length, and is broad in proportion.
The extremity of this organ, called the Glans of the Clitoris,
forms a small tubercle, which is covered above and on the sides
by a small plait or fold of the skin denominated Prepuce.
These parts are lubricated by a secretion similar to that which
is observed round the glans penis.

NYMPHJ;. 185

The crura of the clitoris have muscles similar to the erectores
penis. The interior structure of the Clitoris is very similar to
that of the corpora cavernosa of the penis, or the corpus spon-
giosum of the urethra. It appears constructed for a similar
distension, and is endued with the same sensibility as the penis.
The two lateral parts are also separated from each other by a
septum, resembling that of the penis. It is united to the sym-
physis pubis by a ligament.

The Prepuce of the clitoris has a semicircular form : below
its extremities two folds or plaits commence, one on each side,
which are situated obliquely with respect to each other, so as
to form an angle. These folds-are denominated the Nympha.

The NymphfZ or Labia Interna extend from the clitoris
downwards nearly as far as the middle of the orifice of the
vagina. They are situated within the external labia, and are
formed by the skin after it has become more delicate in its
texture. Their surface, however, is often somewhat corrugated.
There are many blood-vessels in their internal structure, and
it is supposed they are occasionally somewhat tumid. They
are flat, and their exterior edge is convex ; so that they are
narrow at their extremities, and broad in the middle. Their
breadth is very variable, and in some instances is great. In a
majority of cases, it is equal to one-fourth of their length. Their
color in young subjects is of a bright red ; in women advanced
in years, and who have had many children, they are of a brown
red, and sometimes of a dark color.

The use of these parts is not very evident. They have been
supposed to regulate the course of the urine as it flows from the
urethra, but their effect in this respect is not great. They have
also been supposed to favor the necessary enlargement of the
parts in parturition.

— The nymphae are larger usually in blacks than whites.
They descend some distance below the labia externa, and con-
stitute the tabUcrs or aprons of the " Hottentot females. The
nymphae are very vascular.

— The triangular and slightly concave depression, between the
labia interna, about an inch or an inch and a quarter in length,
16*

186 HYMEN. VAGINA.

is called the Vestibulum. The space between the posterior part
of the orifice of the vagina, and the fourchette is called the Fossa
Navicularis. On the surface of both these parts are observed
a great number of mucous follicles. —

The orifice of the urethra is situated about an inch and one
quarter farther inward than the clitoris. It is often rather less
than the diameter of the urethra, and is somewhat protuberent.
The orifices of mucous ducts are to be perceived around it.

The orifice of the urethra is at the commenceraent of the
canal of the vagina. Immediately within this orifice is situated
the membrane denominated Hymen.

The Hymen is an incomplete septum, made by a fold or
duplicature of the membrane which forms the surface contigu-
ous to it. Sometimes it is circular, with an aperture in the
centre. Sometimes it has a resemblance to the crescent, the
aperture being at the upper part of it. The hymen has fre-
quently been found without a perforation, and has therefore
prevented the discharge of the menstrual evacuation. It is
generally ruptured in the first intercourse of the sexes ; and
some small tubercles, which are found on the surface of the
vagina near the spot where it was situated, are supposed to be
the remains of it. These tubercles are called Caruncula
Myrtiformes.

— Dr. Duvernoy, has found the hymen to exist in many of
the inferior animals, in which it varies in regard to form, pre-
cisely as it does in the human race. —

Of the Vagina.

The canal of the vagina, commencing at the hymen and the
orifice of the urethra, is rather more narrow at its beginning
than it is farther inward. From this place it extends backwards
and upwards, and partakes in a small degree of the curve of
the rectum: while the bladder, which is above it, and rests upon
it, increases the curvature of the anterior part. It is much
larger in women who have had children than in those who
have not.

CORPORA CAVERNOSA VAGINA.

187

— In the virgin state at puberty, its length is about five
inches, and its breadth when moderately distended, one inch.
In a natural state of the parts, there is no cavity, the surfaces of
the mucous membrane being in contact. In women who have
borne many children, its length diminishes, and its breadth
increases in inverse proportion with its length. —

Fig. no*

* A side view of the viscera of the female pelvis. 1. The symphysis pubis ; to
the upper part of which the tendon of the rectus muscle is attached. 2. The
abdominal parietes. 3. The collection of fat, forming the projection of the mons
Veneris. 4. The urinary bladder. 5. The entrance of the left ureter. 6. The
canal of the urethra, converted into a mere fisshure by the contraction of
its walls. 7. The meatus urinarius. 8. The clitoris, with its praepuiium,
divided through the middle. 9. The left nympha. 10. The left labium majus.

11. The meatus of the vagina, narrowed by the contraction of its sphincter.

12. The canal of the vagina, upon which the transverse rugae are apparent.

13. The thick wall of seperation between the base of the bladder and the vagina.

14. The wall of separation between the vagina and rectum. 15. The perine-
um. 16. The OS uteri. 17. Its cervix. 18. The fundus uteri. The cavitas
uteri is seen along the centre of the organ. 19. The rectum, showing the
disposition of its mucous membrane. 20. The anus. 21. The upper part of
the rectum, invested by the peritoneum. 22. The recto-uterine fold of the
peritoneum. 23. The utero-vesical fold. 24. The reflection of the peritoneum,
from the apex of the bladder, upon the urachus to the internal surface of the
abdominal parieties. 25. The last lumbar vertebra. 26. The sacrum. 27.
The coccyx.

188 CORPORA CAVERNOSA VAGINAE.

The membrane which lines the vagina resembles to a certain
decree, the membranes which secrete mucus in different parts
of the body. Its surface appears to consist of very small
papillae ; and at the anterior extremity of the vagina it forms
a great number of rugae, which are arranged in a transverse
direction, both on the part of the vagina connected to the blad-
der, and on that part which is connected to the rectum, while
the lateral parts of the vagina are smooth. These rugae are
most prominent in the middle ; so that a raised line appears to
pass through them at right angles. This line extends from
without inwards. The, rugae on the part next to the bladder
are the strongest.

This arrangement of the surface of the vagina does not ex-
tend beyond the external half of the canal ; on the internal
half part, or that nearest the uterus, the surface is smooth.

The rugae are considerably diminished in women who have
had children.

Throughout this surface are to be seen, in some cases with
the naked eye, the orifices of mucous follicles or ducts, which
occasionally discharge considerable quantities of mucus.

— Near the external orifice of the vagina, exist a couple of
little glands, somewhat resembling those of Cowper, which
discharge through their ducts a lubrifying mucus on the surface of
the membrane. —

Exterior to the lining membrane of the vagina is a dense
cellular structure, which has not yet been completely investi-
gated : it is of a lightish color, and has some resemblance to
the texture of the body of the uterus. It is very vascular, and
appears to be of a fibrous structure. It may be very much
distended, and seems to have a contractile power.

At the anterior extremity of the vagina, on each side of it,
there is superadded to this, a cellular, or vascular substance,
from eight lines to an inch in breadth : which, when cut into,
resembles the corpora cavernosa, of the corpus spongiosum of
the penis. These bodies commence near the body of the cli-
toris, and extend downwards on each side of the vagina. They
have been called Plexus Retiformis, and Corpora Cavernosa

rnkm^^

UNIMPREGNATED UTERUS. 189

Vagina, and are occasionally distended with blood, like the
clitoris and penis.

These corpora cavernosa are covered by muscular fibres,
which pass over them on each side from the sphincter ani to
the body of the clitoris ; to each of which organs they are
attached. These fibres constitute the sphincter vagina muscle,
and contract the diameter of the vagina at the place where
they are situated.*

The transversus perinei muscles also exist in the female.
They pass from the tuberosities of the ischia, and are inserted
into a dense whitish substance in the perineum, to which the
anterior extremity of the sphincter ani is likewise attached.

The vagina is in contact with the rectum behind ; the
bladder lies upon it and anterior to it. A small portion of
peritoneum, to be reflected to the rectum, is continued from the
uterus upon the posterior part of it. The lateral portions of
it are invested with cellular substance. The anterior extremity
of the uterus, which is called the Os Tincae, projects into it
from above.

Of the Uterus, the Ovaries and their Appendages.

The Uterus has been compared to a pear with a long neck.
There is, of course, a considerable difference between the
body and neck ; the first being twice as broad as the last.
Each of these parts is somewhat flattened.

In subjects of mature age, who have never been pregnant,
the whole of the uterus is about two inches and a half in
length, and more than one inch and a half in breadth at the
broadest part of the body : it is also near an inch in thickness.

It is generally larger than this in women who have lately
had children.

The uterus is situated in the pelvis between the bladder and
rectum, and is enclosed in a duplicature or fold of the perito-
neum, which forms a loose septum that extends from one side

* These two muscular bands, which when conjoined together form the sphinc-
ter vaginas, have a similar origin and insertioQ and correspond with the accele-
ratore urins muscles of the male. — p.

190 LIGAMENTS OF THE UTERUS.

of the pelvis to the other, and divides it into an anterior and
posterior chamber. The posterior surface of this septum is
opposed to the rectum, and the anterior to the bladder. The
two portions of this septum which are between the uterus and
the lateral parts of the pelvis, are called the Broad Ligaments.

On the posterior surface, the Ovaries are situated on each
side of the uterus, being enclosed by a process of the ligament
or septum. Above them, in the upper edge of the septum, are
the Fallopian Tubes, which are ducts that commence at the
upper part of the uterus on each side, and proceed in a lateral
direction for some distance, when they form an angle and
incline downwards to the ovaries. These ducts are enclosed
between the two lamina of the septum for the greater part of
their length.

The peritoneum which forms the septum, is reflected from
it, posteriorly, to the rectum, and the posterior surface of the
pelvis, and anteriorly to the bladder. In its progress in each
direction, it forms small plaits or folds ; two of which extend
from the uterus to the rectum posteriorly, and two more to the
bladder anteriorly : these are called the Anterior and Posterior
Ligaments of the Uterus.

The other ligaments, which proceed more immediately from
the uterus are called the Round Ligaments. These arise from
each side of the uterus, at a small distance before and below
the origins of the Fallopian tubes, and proceed in an oblique
course to the abdominal rings. These ligaments are also
invested by the peritoneum. They pass through the rings and
soon terminate in the fatty structure of the mons veneris.

In the body of the uterus is a cavity, which approaches to
the triangular form, and from which a canal proceeds through
its neck. This cavity is so small that its sides are almost in
contact, and the canal is in proportion ; so that this organ is
very thick in proportion to its bulk.

The substance of which the uterus consists is very firm and
dense: it is of a whitish color, with a slight tinge of red.
There are many blood-vessels, with nerves and absorbent
vessels, in its texture. The nature and structure of this sub-

FIBRES OF THE UTERUS. 191

Stance, has not yet been precisely ascertained. It appears very
different indeed from muscle ; but the uterus occasionally con-
tracts, with great force, during labor. It is not rendered thin
by its enlargement during pregnancy, and the blood-vessels in
its texture are generally enlarged at that time.

— The proper tissue of the uterus in its ordinary condition,
is of a grayish color, and of a density almost cartilaginous,
especially in its neck. It is composed of fibres, the nature and
arrangement of which it is then impossible to determine.
When enlarged by gestation, its tissue is soft, reddish, very
dilatable, contractile, and presents all the characters of muscular
tissue. Its fibres* are arranged in the following manner : —
— In the body of the uterus they form two layers, one super-
ficial and one deep-seated. The former is composed first, of a
vertical fasciculus, which runs over the anterior and posterior
faces of the organ ; of a second fasciculus, which runs along
the superior border of the fundus, and of several other oblique
layers, which may be traced upon the Fallopian tubes, round
ligaments, broad ligaments, and ligaments of the ovaries. In
many animals, as in the cow, we find the broad ligament a
mass of muscular fibres continuous with the uterus.
— The second or deep-seated, form two cones, which are con-
nected by their basis upon the median line, and by their apices
to the Fallopian tubes. The neck of the uterus is composed
entirely of circular fibres, closely compacted together. —

Exteriorly, the uterus is covered by the peritoneum, as has
already been mentioned. Internally it is lined with a delicate
membrane that has some resemblance to those which secrete
mucus, and is generally of a whitish color, abounding with
small orifices that can be seen with a magnifying glass. This
membrane is so intimately connected to the substance of the
uterus, that some anatomists have supposed it was merely the
internal surface of that substance, but this opinion is now
generally abandoned. It is supposed that the color of this
membrane is more florid about the period of menstruation.

* The best description of the fibres of the uterus is that of Madame Boivin,
Vide Maladies de I'Uierus, etc., by Mad. Boivia and A. Dugus. Paris.— p.

192 CAVITY OF THE UTERUS.

The cavity of the uterus, as has been observed before, is
triangular in form. When the organ is in its natural position,
the upper side of this triangle is transverse with respect to the
body, and the other sides pass downwards and inwards. In
each of the upper angles are the orifices of the Fallopian tubes,
which are of such size as to admit a hog's bristle.

The two lower lines of the triangle are slightly curved
outwards at their upper extremities ; so that the upper angles of
the triangle project outwards and the orifices of the Fallopian
tubes are nearer to the external surface than they otherwise
would be.

The lower angle of the cavity of the uterus is occupied by
the orifice of the canal, which passes through the neck of the
organ ; this orifice is from three to four lines in diameter. The
canal is about an inch in length, and is rather wider in the
middle than at either end. On the anterior and posterior por-
tions of its surface are many small ridges which have an arbor-
escent arrangement, one large ridge passing internally from the
commencement of the canal, from which a number of other
ridf^es go off in a transverse direction. These ridges extend
nearly the whole length of the canal. In the grooves, between
the ridges, are the orifices of many mucous ducts.

— These folds or ridges all disappear during gestation, and
their singular arrangement serves to explain, how the neck
is capable, when expanded, of forming a third part of the gene-
ral uterine cavity, at the latter period of gestation. —

There are also on the surface a number of transparent bodies
of a round form, equal in bulk to a middle-sized grain of sand,
the nature and use of which is unknown. They have been
called Ovula Nabothi, after a physiologist who published some
speculations respecting their use, about the commencement of
the last century.

— These are now generally believed to be the mucous follicles
of the neck of the uterus in a state of vesicular distention, the
orifices of which have been obliterated, —

The canal of the neck of the uterus is very different from
other ducts, for it seems to be a part of the cavity to which it

THE FALLOPIAN TUBES. 193

leads, and when the cavity of the uterus becomes enlarged in
the progress of pregnancy, this canal is gradually converted
into a part of that cavity.

The lower extremity of the neck of the uterus is irregularly
convex and tumid. The orifice of the canal in it, is oval, and
so situated that it divides the convex surface of the neck into
two portions, which are called the Liys. The anterior or upper
portion is thicker than the other.

This extremity of the uterus protrudes into the vagina, and
is commonly called Os Tinea. As the anterior portion or lip is
larger and more tumid than the posterior, the vagina extends far-
ther beyond the os tincae on the posterior part than on the anterior.

The Fallopian Tubes (or Oviducts)

Are two canals, from four to five inches in length, which
proceed between the lamina of the broad ligaments, from the
upper angles of the uterus, in a transverse direction, to some
distance from the uterus, when they form an angle, and take a
direction downwards towards the ovaries.

They are formed, for a considerable part of their extent, by
a substance which resembles that of which the uterus consists,
and are lined by a membrane continued from the internal
membrane of the uterus. Their extremities appear to be com-
posed of membrane, which is rendered florid by the blood-ves-
sels in its texture. At the commencement, their diameters are
extremely small ; but they enlarge in their progress. This
enlargement is gradual for the first half, and afterwards 'sudden j
the enlarged part is more membranous than the small part,
and has a bright red color. The large extremity is loose in
the cavity of the pelvis, and is not invested by the lamina of
the broad ligaments. Near the termination the diameter is
often contracted ; after which the membrane which forms the
tube expands into an open mouth, the margin of which consists
of fringed processes : tliis margin is also oblique, as respects
the axis of the tube ; and the different fringed processes are
not all of the same length ; but the longest are in the middle^
and the others regularly diminish on each side of them : these
processes constitute the Fimbricc of the Fallopian tubes.
VOL. II. 17

194 THE FALLOPIAN TUBES.

The interna] surface of the large extremities of these tubes
is extremely vascular; and there are some longitudinal fibres
of a red color to be seen on it.

— More recent investigations into the structure of the walls of
the Fallopian tubes, have shown that they are composed of an
inner lining of mucous membrane which is covered with a deli-
cate ciliary epithelium, a middle or muscular coat consisting of
circular and longitudinal fibres continuous with those of the
uterus and an external serous tunic derived from the peritoneum.
The great abundance and frequent anastomosis of the veins in
the walls of the tubes, forms a sort of erectile spongy body, some-
what like the corpus spongiosum. — When this spongy substance
is distended by a fine size injection, I have found the tube bowed
upwards as if in a state of erection, and the Fimbria or Morsus
Diaholi, which are likewise rendered turgid, spread out upon the
ovary, so that the dilated funnel-shaped cavity of the tube, the
ostium abdominale, was brought in contact with this organ. One
or two of the longest of these fimbrias are usually attached to the
external margin of the ovary. Sometimes they are all found
adherent as a consequence of accidental inflammation. In a
young girl dead six or seven weeks after conception, Madame
Boivin, found the trumpet-shaped extremity of the left tube curv-
ed over the ovary so as to cover it almost entirely, and all the
fimbriae strongly adherent to its surface. At the orifice of the
tube was a membranous cyst, of the size of a hazle-nut, filled with
a yellowish serum, and covered with minute red vessels. This
interesting fact is in support of the function attributed to these
oro-ans during fecundation : that of grasping the ovary with its
fimbria, and sucking in the ovum when detached, which it trans-
mits in ordinary cases to the womb.

— There is reason to believe, that the pathological changes of
the distal extremity of this tube, are a frequent cause of sterility.
It is so commonly found diseased in the class of subjects with
which our anatomical rooms are supplied, that it is even diffi-
cult to procure a perfectly healthy specimen of the parts. The
morbid changes that I have most frequently met with, are an
agglutination of the end of the tube to the ovary or broad liga-

THE OVARIES. 195

ments, its occlusion by inflammation or the development in it
of hydatid vesicles. —

The Round Ligaments

Which have already been mentioned, are cords of a fibrous
structure, with many blood-vessels in them. They arise from
the uterus below the origin of the Fallopian tubes, and proceed
under the anterior lamina of the broad ligaments to the abdo-
minal rings through which they pass ; and then the fibres and
vessels are expanded upon the contiguous cellular substance of
the mons veneris and labia externa.

The Ovaries, (Testes Muliebi-es,)

Are two bodies of a flattened oval form ; one of which is
situated on each side of the uterus on the posterior surface of
the broad ligament, and invested completely by a process of
the posterior lamen, which forms a coat, and also a ligament
for it. The size of this organ varies in different subjects, but
in a majority of those who are about the age of maturity, it is
between ten and twelve lines in length. It is connected to the
uterus by a small ligament (called ovarian) or bundle of fibres
of the same structure with the round ligaments, which is not
more than two lines in diameter, and is included between the
lamina of the broad ligament.

The process of the broad ligament forms an external serous
coat to the ovary ; within this is the proper coat of the organ,
(tunica albuginea,) which is a firm membrane. This membrane
is so firmly connected to the substance of the ovary which it
encloses, that it cannot be easily separated from it. The ovary
is of a whitish color and soft texture, and has many blood-vessels.
In virgins of mature age it contains fiorn ten to twenty vesicles,
formed of a delicate membrane, filled with a transparent coagu-
lable fluid. Some of these vesicles are situated so near to the
surface of the ovary, that they are prominent on its surface ;
others are near the centre. They are very different in size ; the
largest being between two and three lines in diameter, and others
not more than one-third of that size.

In women who have had children, or in whom conception has

196 VESICULiE GRAAFIANJE.

taken place, some of tliese vesicles are removed, and In their
place a cicatrix is found.

It has been ascertained, that during the sexual intercourse
with males, one of these vesicles, which was protuberant on
the surface, is often ruptured, and a cavity is found. A cicatrix
is soon formed, where the membrane was ruptured ; and in the
place occupied by the vesicle there is a yellow substance denom-
inated Corpus Luteum. This corpus luteum generally contin-
ues until the middle of pregnancy : it often remains during that
state, and for some time after delivery, but it gradually vanishes.
The cicatrization continues during life.

In many cases these cicatrices correspond with the number of
conceptions which have taken place ; but they often exceed the
number of conceptions, and they have been found in cases where
conception has not been known to have taken place.

In very old subjects, where conception has never taken place,
the vesicles are either entirely removed, or small dense tubercles
only remain in their place.

— These vesicles have been called the ovaov vesiculce GraaJlancE,
in honor of Regnier De Graaf, who described them with care,
though their existence had been previously pointed out by
Vesalius and Fallopius.

— These vesicles, as they increase in size at the approach of pu-
berty, or from the effect of sexual excitation, make their way
gradually to the surface through the stroma, or parenchymatous
structure of the ovary. In two Instances where death had occur-
red under peculiar circumstances, I have seen vesicles of the
largest size seated as it were, in a little cup-like depression of the
ovary, with the peritoneal lining raised in relief above them. A
slight blush of inflammation could be seen on the walls of the
vesicles, through the peritoneum, which corresponds with the
description given by De Graaf, of the first stages of conception in
the cow. One of these ovaries I steeped in boiling water, and
found the vesicles it contained, the largest of which was about
three lines in diameter, to consist of two membranes, separable
from each other, the inner one containing a limpid albuminous
fluid, which had been coagulated by the heat. The outer one of
these membranes is called the ovular capsule, or the tunica ^ro-

VESSELS OF THE UTERUS. 197

jjria ovisacci, as It was named by Barry. The second or internal
forms the proper ovisac. By the aid of the microscope, a third
membrane, of a serous character, and granulated on its surface
(membrana granulosa), is found lining the ovisac. In the midst
of the albuminous fluid contained by the third membrane floats
lightly attached, the proper ovum or ovule a minute spherical or
rather oblong body, from the \^ to the |=r part of a line in diameter.
The proper germ or ovum, which finally escapes by the lacera-
tion of the walls of the vesicles after conception is taken up by
the prehensile action of the Fallopian tube and transmitted to the
uterus. The lacerated walls of the vesicle, give issue to some
blood, secrete a yellowish fluid, become fibrous and spongy and
finally cicatrise over a central cavity in which the ovum has been
lodged, and thus constitute the corpus luteum. False corpora
lutea, are sometimes m.et with in the ovaries of the virgin, having
a somewhat similar appearance to the foregoing, but being of smal-
ler size and without any central cavity.

The Arteries

Of the uterus are derived from two very different sources ;
namely, from the spermatic and from the hypogastric arteries.

The spermatic arteries, instead of passing directly down to
the abdominal ring, proceed between the lamina of the broad
ligament, and send branches to the ovaries, which may some-
times be traced to the vesicles. They also send branches to
the Fallopian tubes and to the uterus. Those which are on the
opposite sides of the uterus anastomose with each other, and
also with the branches of the hypogastric arteries. There are
also branches of these arteries in the round ligaments which
accompany them to their termination outside of the abdominal ring.

The principal arteries of the uterus are those derived from
the hypogastric, which sends to each side of it a considerable
branch, called the Uterine. This vessel leaves the hypogastric
very near the origin of the internal pudic, and proceeds to the
cervix of the uterus : it passes between the lamina of the
broad ligaments, and sends branches to the edge of the uterus,
which penetrate its texture. The branches which are in the
texture of the uterus are very small, indeed, in young subjects.
17*

198 THE LYMPHATIC VESSELS.

In women who have had children, they are considerably
larger ; but during pregnancy they gradually enlarge with the
growth of the uterus, and become very considerable. These
arteries observe a serpentine and 'peculiarly tortuous course.
Those on the opposite sides anastomose with each other.

The Veins

Of the uterus, like the arteries, form spermatic and uterine
trunks. The spermatic vein is much larger than the artery. It
ramifies, as in males, and forms a very large plexus, which
constitutes the corpus pampiniforme. Many of the veins which
form this body, originate near this ovary : a considerable num-
ber also come from the Fallopian tubes and the uterus. The
spermatic vein and its branches are greatly enlarged indeed
during pregnancy ; and it is said that they are enlarged the
same way during the menstrual discharge.

The most important veins of the uterus are the branches of
the Uterine Veins. They are extremely numerous, and form
a plexus on the side of the uterus ; from which two or more
uterine veins proceed in the course of the artery, and join the
hypogastric. These veins also are greatly enlarged during
pregnancy. Some of these are so large as to receive the end of
the little finger, and are called uterine sinuses, though improperly.

The Lymphatic Vessels

Of the uterus, and its appendages, are very numerous. In
the unimpregnated state they are small ; but during pregnancy
they increase greatly. They proceed from the uterus in very
different directions. Some that accompany the round ligaments
go to the lymphatic gland of the groin. Others, which take
the course of the uterine blood-vessels, pass to glands in the
pelvis, and a third set follows the spermatic arteries and veins
to the glands of the loins.

The Nerves

Of the ovaries are derived from the renal plexus, and those
of the uterus and vagina from the hypogastric plexus, or the

THE BLADDER AND URETHRA. 199

lower portions of the sympathetic, and the third and fourth
sacral nerves.

Of the Bladder and Urethra.

The situation of the Bladder, as respects the synaphysis
pubis, is nearly alike in both sexes; but that part of it which
is immediately behind the insertion of the uterus is rather lower
in males than in females. The bottom of the bladder rests
upon the upper part of the vagina, a thin stratum of cellular
substance intervening : when that viscus is distended it forms a
tumor which compresses the vagina.

The ureters are inserted, and the urethra commences in the
same part of the bladder, in both sexes.

The length of the Urethra is between one and two inches.
When the body is in an erect position, it is nearly horizontal ;
but it is slightly curved, with its convexity downwards. It is
immediately above the vagina, and it passes below the body of
the clitoris. The external orifice is rather more than an inch
within the glans or head of the clitoris. This orifice is some-
what prominent in the vagina.

— In young persons, the external orifice of the urethra is
immediately below the symphysis of the pubis, and nearly
level with the anterior face of that bone.

— In women who have borne many children, the urethra is
retracted or shortened, so as to be rarely more than an inch and
a quarter in length, and the orifice will be found behind the pubis,
near its posterior face. A knowledge of these facts will render
the introduction of the catheter in many cases more easy. —

In the internal lining membrane of the urethra there are
many orifices of mucous follicles, and also longitudinal wrinkles,
as in the urethra of males. The diameter of the female urethra
and its orifice in the bladder are larger than they are in the male.
For this reason it has been supposed, that women are less liable
to calculus of the bladder than men.*

The urethra is intimately connected with the external coat
of the vagina, and between them there is a spongy cellular

* It has, however, been asserted tliat they are also less liable to calculi in the
kidneys.

200 GENERAL CHANGES IN THE UTERUS.

substance which makes the rough surface of the vagina promi-
nent ; so that the urethra has been supposed, although errone-
ously, to be invested with the prostate. It is capable of great
artificial dilatation. Its diameter in the natural state is about a
quarter of an inch. •

Of the Changes induced in the Uterus hi the progress of
Pregnancy.

The alteration which takes place in the size of the uterus
during pregnancy is truly great. About the conclusion of that
period, instead of the small body above described, which is
almost solid, the uterus forms an immense sac, which extends
from the termination of the vagina in the pelvis, into the epi-
gastric region, and from one side of the abdomen to the other;
preserving, however, an ovoid figure.

This change is so gradual at first, that the uterus does not
extend beyond the cavity of the pelvis before the third month,
although at the end of the seventh month it is very near the
epigastric region.

For the first six months the body of the uterus appears prin-
cipally concerned in the enlargement : after this the cervix be-
gins to change, and is gradually altered so as to compose a
portion of the sac, of rather less thickness than the rest of the
uterus ; the mouth being ultimately an aperture in a part which
is much thinner than the other portions of the organ. ^

The change which takes place in the texture of some of the
appendages of the uterus is very important.

The Broad Ligaments, which seem particularly calculated
to favor the extension of the uterus, are necessarily altered by
the change in the size of that organ, but not entirely done
away. The portion of peritoneum of which they are formed
must be very much enlarged with the growth of the uterus, as
it continues to cover it. The Round Ligaments are much
elongated ; and they observe a more straight course to the
abdominal ring. The Fallopian Tubes are enlarged ; and
instead of passing off laterally from the uterus, they now proceed

GENERAL OBSERVATIOxNS. 201

downwards by the side of it. The Ovaries appear rather larger
and more spongy : their relative situation is necessarily lower.

The change in the Uterus itself is particularly interesting.
The great increase of its size is not attended with any conside-
rable diminution of thickness in its substance ; nor are the
arteries much less convoluted than before pregnancy, as
might have been expected. They are greatly enlarged in
diameter, and the orifices of the exhalent vessels on the internal
surface of the uterus are much more perceptible.

The veins are much more enlarged than the arteries, and in
some places appear more than half an inch in diameter. They
are not regularly cylindrical, but rather flat. They anastomose
so as to form an irregular net-work.

The uterus appears much more fibrous and muscular in the
gravid than in the unimpregnated state. The contractile power
of the gravid uterus is not only proved by the expulsion of its
contents, but also by very vigorous contractions, which are
occasionally observed by accoucheurs.

Although the general effects which result from the particular conditions of the
uterus in pregnancy, menstruation, <^:c., evince that the influence of this
organ upon the whole system is very great, yet it seems probable that the sex-
ual peculiarities of females are especially dependent upon the ovaria.

This sentiment is confirmed by an account of a woman in whom the ovaria
were deficient, which is published in the London Philosophical Transactions
for 1805, by Mr. C. Pears. The subject lived to the age of twenty-nine years.
She ceased to grow after the age often years, and therefore was not more
than four feet six inches in height : her breadth across the hips was but nine
inches, although the breadth of the shoulders was fourteen. Her breast and
nipples were never enlarged more than they are in the male subject. There
was no hair on the pubis, nor were there any indications of puberty in mind
nor body. She never menstruated. At the age of twenty-nine she died of a
complaint in the breast, attended with convulsions. The uterus and os tineas
were found not increased beyond their usual size during infancy. The cavity
of the uterus was of the common shape, but its coats were membranous. The
Fallopian tubes were pervious. " The Ovaria rvere so indistinct that they rather
showed the rudiments which ought to have formed them, than any part of the
natural structure.

Another case, which confirms the aforesaid sentiment, is related in one of the
French periodical publications.

It has been long known that a race of savages near the Cape of Good Hope
were distinguished from the generality of their species by a peculiarity about
the pitdendum. An account of this structure has been given with some
precision by Messrs. Peron and Lesueur, in a paper which was read to the

202 PECULIARITIES IN THE ABDOMEN OF THE FffiTUS.

National Institute of France. It is a flap or apron, four inches in length,
which is united to the external labia near their upper angle, and hangs dowa
before the clitoris and the external orifice of the parts of generation. It is
divided below into two lobes, which cover the orifice. It is formed by a soft
distensible skin, free from hair, which is occasionally corrogated like the
scrotum, and is rather more florid than the ordinary cutis.* — This is the
tablier, or mere natural enlargement of the nymphje, common to the females
of some races of men. —

The Abdomen of the Fcetus.

The difference between the foetus and the adult, in the cavity
of the abdomen, is very conspicuous at the first view.

The Liver in the foetus is so large that it occupies a very con-
siderable part of the abdomen. Its left lobe, which is larger in
proportion than the right, extends far into the left hypochondriac
region.

The Bladder of urine, when filled, extends from the cavity
of the pelvis a considerable distance towards the umbilicus :
so that the greatest part of it is in the cavity of the abdomen.
A ligament of a conical figure extends from the centre of the
upper part of the bladder to the umbilicus, with an artery on
each side of it, which is soon to be described. This ligament,
which is in the situation of the urachus of the foetus of quad-
rupeds, is hollow, and thus frequently forms a canal, which
has a very small diameter, that communicates with the bladder
by an aperture still smaller, and continues a short distance from
the bladder towards the umbilicus. In a few rare instances, this
canal has extended to the umbilicus, so that urine has been
discharged through it, but the ligament is commonly solid there.

The Stomach appears to be more curved in the foetus than in
the adult.

The Great Intestine does "not extend sufficiently far, beyond
the insertion of the ileon, to form the Ccccum completely.

The Glandula, Renales are much larger in proportion in the
foetus than in the adult. The color of the fluid they contain
is more florid.

The Kidneys are lobulated.

* This paper has not yet been published by the Institute, but it is referred to
by M. Cuvier in his Le^onesd' Anatomic Comparee, vol. v. page 124. — Blessrs.
Peron and Lesueur were naturalists who accompanied captain Baudin in his
voyage of discovery ; the latter has been for some years resident in Philadelphia.

DESCENT OF THE TESTICLE OF THE FCETUS. 203

The Testicles in the foetus are found above the pelvis, in the
lumbar region, behind the peritoneum until two months before
birth. Thus situated, their blood-vessels and nerves proceed
from sources which are near them ; but the vas deferens, being
connected to the vesiculae seminales by one extremity, is neces-
sarily in a very different situation from what it is in the adult :
it proceeds from the testicle downwards to the neck of the
bladder. While each testicle is in this -situation, it is connected
with a substance or ligament, called Gubernaculum, of a coni-
cal or pyramidical form, \vhich is attached to its lower end, and
extends from it to the abdominal ring. This substance is vas-
cular, and of a fibrous texture : its large extremity adheres to
the testicle, its lower and small extremity passes through the
abdominal ring, and appears to terminate in the cellular sub-
stance exterior to that opening, like the round ligament in
females. The Gubernaculum, as well as the testicle, is
behind the peritoneum ; and the peritoneum adheres to each
of them more firmly than it does to any of the surrounding
parts. It seems that, by the contraction of the Gubernaculum,
the testicle is moved down from its original situation to the
abdominal ring, and through the abdominal ring into the scro-
tum. The peritoneum, which adheres firmly to the gubernac-
ulum and testicle, and is loosely connected to the other parts,
yields to this operation ; and when the testicle has arrived near
the abdominal ring, a portion of the peritoneum is protruded a
little way before it into the scrotum ; forming a cavity like the
finger of a glove. The testicle passes down behind this process
of the peritoneum, and is covered by it as it was in the abdomen.
Although it appears protruded into the cavity, it is exterior to
it ; and behind it ; and the vessels, he, which belong to the
testicle are also exterior to it.

The cavity formed in the scrotum, by this process of the
peritoneum, necessarily communicates with the cavity of
the abdomen at its formation ; but very soon after the testicle
has descended into the scrotum, the upper part of this cavity
is closed up, while the lower part of the process continues
unchanged, and constitutes the Tunica Vaginalis Testis. In
some instances the upper part of this process does not close up,

204

UMBILICAL VESSELS.

Fig. 171.* and the communication with the cavity
n of the abdomen continues. The descent

of the intestine into the cavity thus cir-
cumstanced, constitutes that species of
hernia which is denominated Conge-
nit a Lf

The most important peculiarities in
the abdomen of the foetus are those con-
nected with the circulation of the blood.
The internal iliac or hypogastric arte-
ries are larger than the external iliacs.
Their main trunks are continued on
each side of the bladder to its fundus,
and proceed from it, with the ligament,
to the umbilicus ; when they pass out of
the abdomen to go along the umbilical
cord to the placenta. These arteries are
now denominated the Umbilical, and
are very considerable in size. After birth, as there is no cir-
culation in them, they soon begin to change : their cavity
becomes gradually obliterated, and they are converted into

* Diagram of the circulation of the human foetus. 1, 1, Umbilical arteries.
2, Umbilical vein. The blood of the umbilical vein is partly distributed to the
liver, in the right tube of which it becomes mixed with the blood of the porta,
and in part passes directly by the ductus venosus 3, to the vena cava inferior, 4.
5, Vense cava; hepaticse or hepatic veins. 6, Superior cava. 7, Right auricle.
8, Pulmonary veins. 9; Left auricle. 10. Left ventricle. 11, Ascending aorta
or left arch of the aorta. 12, Vessels to the head and upper extremities. 13, Right
ventricle. 14, Ductus arteriosus, or right aortic arch. 15, Descending aorta. — p.

t These interesting circumstances respecting the original situation of the tes-
ticle, and its descent into the scrotum, were discovered and elucidated by Haller,
Hunter, Pott, Camper, and several other very respectable anatomists and sur-
geons. There is, however, a difference of opinion between some of them, as to
the time when the testicle leaves the abdomen. Haller thought the testicles
were seldom in the scrotum at birth. Hunter and Camper found them so
generally.

It has been suggested that there are some national peculiarities in this respect ;
that amongst the Hungarians, for example, the testicles often remain above the
abdominal ring until near the age of puberty.

The student will find an interesting description of the situation of the testis,
and its descent in the foetus, in the " Observations on certain parts of the Animal
Economy," by John Hunter.

THE UMBILICAL VESSELS. 205

ligaments. They are exterior to the peritoneum, and contained
in a duplicature of it.

A vein also called the Umbilical, which is much larger in
diameter than both of the arteries, returns from the placenta
along the cord, and enters the cavity of the abdomen at the
umbilicus. It proceeds thence, exterior to the peritoneum,
but in a duplicature of it called the Falciform Ligament, to
the liver, and enters that viscus at the great fissure ; along
which it passes to the left branch of the sinus of the vena
portarum, into which it opens and discharges the blood which
flows through it from the placenta. It opens on the anterior
side of the branch of the vena portarum, and from the posterior
side of the branch, opposite to this opening, proceeds a duct or
canal, which opens into the left hepatic vein near its junction
with the vena cava. This communicating vessel is called the
Ductus, or Canalis Venosus ; to distinguish it from the duct
which passes from the pulmonary artery to the aorta, and is
called Ductus, or Canalis Arteriosus. This venous duct car-
ries some of the blood of the umbilical vein directly to the vena
cava ; but it is much smaller than the umbilical vein, and of
course a considerable quantity of the blood which passes
through the umbilical vein must pass through the liver by the
vena portarum, before it can enter the cava.

In some foetal subjects, if a probe of sufficient length be in-
troduced within the umbilical vein, and pushed forwards, it will
pass to the heart, without much difficulty or opposition,
as if it proceeded along one continued tube, although it really
passes from the umbilical vein across the branch of the vena
portarum, and then through the ductus venosus, and through
a portion of the left hepatic vein, into the inferior vena cava.

If the umbilical vein be injected with a composition, which
will be firm when cool, it appears to terminate in a rounded
end, which is situated in the transverse fissure of the liver : the
sinus of the vena portarum, into which this vein enters, appears
like two branches going off, one from each side of it, and the
ductus venosus like a branch continuing in the direction of the
main trunk of the umbilical vein.
VOL. II. 18

206 UMBILICAL VESSELS.

The umbilical vein, in its progress through the fissure of the
liver, before it arrives at the sinus of the vena portarum, sends
off a considerable number of branches to each of the lobes of
that organ, but more to the left than to the right lobe.

After birth, when blood ceases to flow through the umbilical
vein, it is gradually converted into a ligament ; and the venous
duct is also converted into a ligament in the same manner.
The vena portarum, which before appeared very small, when
compared with the umbilical vein, now brings all the blood
which fills its great sinus, and increases considerably in size.

It has been ascertained by anatomical investigation, that the
umbilical arteries above mentioned, after ramifying minutely
in the placenta, communicate with the minute branches of the
umbilical vein ; and it is probable that the whole blood carried
to the placenta by these arteries, returns by the umbilical vein
to the foetus.

It is clearly proved by the efTects of pressure on the umbilical
cord, in cases of delivery by the feet, as well as by other similar
circumstances, that this circulation cannot be suspended for any
length of time without destroying the life of the foetus. From
these circumstances, and from the florid color which the blood
acquires by circulating in the placenta, it seems probable that the
object of the circulation through that organ is somewhat analo-
ffous to the object of the pulmonary circulation through the lungs
of adults.*

* During the first four months of pregnancy a very small vesicle, which does
not exceed the size of a pea, is found between the chorion and the amnios, near
the insertion of the umbilical cord into the placenta. It is connected to the
foetus by an artery and a vein, which pass from the abdomen through the
umbilicus, and proceeding along the cord to the plancenta, continue from it to
the vesicle. The artery arises from the mesenteric, and the vein is united to the
mesenteric branch of the vena portarum. It is probable that these vessels com-
monly exist no longer than the vesicle, namely, about four months; but they
have been seen by Haller and Chaussier at the termination of pregnancy. They
are called Omphalo- Mesenteric vessels. The vesicle is denominated the
Umbilical Vesicle.

This intricate structure is delineated in Hunter's Anatomy of the Gravid
Uterus, plate xxxiii. figures v. and vi. ; in the Academical Annotations of Albi-
nus, first book, plate i. figure xii. ; and also in the Icones Embryonum Humano-
rum of Soemmering, figure ii.

PART VIII.

GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.
CHAPTER VII.

OF THE BLOOD-VESSELS IN GENERAL. GENERAL ANATOMY OP THE ARTE-
RIAL SYSTEM. GENERAL REMARKS UPON THE HEART. GENERAL ANAT-
OMY OF THE VENOUS SYSTEM.

Of the Blood-vessels in General.

The blood-vessels are flexible tubes, of a peculiar texture,
through which blood passes from the heart to the different parts
of the body, and returns again from these parts to the heart.
They are to be found, in varying proportions, in almost every
part of the body, and seem to enter into its texture.

The tubes which carry blood from the heart, are more sub-
stantial and more elastic than those through which it returns to
the heart. They are generally found empty after death ; and,
therefore, were called Arteries by the ancient anatomists, who
supposed that they carried air, and not blood.

The tubes which return the blood to the heart are denomi-
nated Veins. They are less substantial and less elastic than
arteries, and are generally fullof blood in the dead subject.

There are two great arteries, from which all the other arterial
vessels of the body are derived. They are very justly compar-
ed to the trunks of trees, and the smaller vessels to their
branches. One of these great arteries, called the Aorta, carries
blood to every part of the body. The other great vessel,
called the Pulmonary Artery, carries blood exclusively to the
lungs.

The veins which correspond to the branches of the Aorta,
unite to each other, so as to form the two great trunks that
proceed to the heart. One of these trunks, coming from the

208 THE BLOOD-VESSELS IN GENEUAL.

superior parts of the body, is called the Superior, or Descending
Vena Cava. The other, which comes from the lower parts of
the body, is called the Inferior, or Ascending Vena Cava.

The veins which correspond with the branches of the Pul-
monary Artery, and return to the heart the blood of the lungs,
are four in number ; two of them proceeding from each lung.
They are called Pulmonary Veins.

Fig. 172.*

In many of the veins there are valves which prevent the
blood they contain from moving towards the surface and
extremities of the body, but allow it to pass towards the heart
without impediment.

From the construction of the cavities of the heart, and the
position of the valves which are in them, as well as the situation
of the valves at the commencement of the great arteries, and
the above mentioned valves of the veins, it is evident, that

* Fig. 172. Trunk of a large vein, laid open in order to exhibit the valves,
formed by doublings of the internal lining membrane, a, Superior portion of
the vein, or that towards the heart, b, Valves, the concavity of which is di-
rected towards the heart, c, Branches of the veins, anastomosing together,
and uniting to form a large branch d, which opens into the principal trunk
at e. — r.

THE SANGUIFEROUS SYSTEM. 209

when the blood circulates, it must move from the heart, through
the aorta and its branches, to the different parts of the body,
and return from these parts through the venae cavse, to the
heart ; that, when deposited in the heart by the venae cavae, it
must proceed through the pulmonary artery to the lungs, and
return from the lungs through the pulmonary veins to the
heart, in order to pass again from that organ into the aorta.

It is also certain, that the blood is forced from the heart into
the arteries, by the contraction of the muscular fibres of which
the heart is composed ; and that the blood-vessels likewise
perform a part in the circulation, they propelling the blood
which is thus thrown into them : but their action appears to
depend upon the causes of a complex nature.

General Anatomy of the Arterial System.

The arteries are so much concerned in the important function
of the circulation of the blood, that every circumstance con-
nected with them is very interesting.

They are composed of coats or tunics, which are very elastic
and strong, and which are also very thick. In consequence of
the firmness of their coats, they continue open, after their
contents are discharged, like hard tubes. They submit to great
dilatation, and elongation, when fluids are forced into them, and
return to their former dimensions when the- distending cause is
withdrawn. This elasticity is particularly subservient to the
circulation of the blood. It admits the artery to distend readily,
and receive the blood which is thrown into it by the contraction
of the heart. It also produces the contraction of the artery;
which takes place as soon as the action of the heart ceases ; and
this contraction of the heart necessarily forces the blood for-
ward, as the valves at its orifice prevent it from returning to
the heart.

The motion of the artery, which is so easily perceived by
the touch, and in many instances also by the eye, is completely
explained by the discharge of blood into the artery from the
heart, and by the elasticity of the vessel, by which it reacts
upon the blood. In some cases it is not simply the diameter

1.8*

210 STRUCTURE OF THE ARTERIES.

of the artery which is enlarged, but a portion of the vessel is
elongated; and this elongation, by producing a curvature of
it, renders its motion more visible.

In the aorta, and probably in its large branches Elasticity
seems to be the principal cause of the continuance of the motion
which is originally given to the blood by the heart. But there
are many circumstances connected with the smaller vessels,
which evince that they exert a power which is very different
indeed from elasticity. Thus, the application of local stimu-
lants or rubefacients, and of heat, is followed by an increase of
action in the arteries of the parts to which they are applied.
Neither of these causes could produce their effect by the influ-
ence of elasticity : but the effect of these and other similar
causes is uniformly produced ; a power of independent motion,
or Irritability, is thus proved to exist in these vessels, and
seems essentially necessary to the circulation of the blood.

The Structure of the Arteries

Is, therefore, a subject of importance, and has received a
considerable degree of attention from anatomists.

They are composed of a dense elastic substance, of a whitish
color. Their external surface is rough, and intimately con-
nected with the cellular membrane, which every where surrounds
it in varying quantities. Internally, they are lined with a
thin membrane, which is very smooth and flexible, and is also
very elastic. The substance which composes the artery, and
is situated between the cellular investment and the internal
membrane, consists of fibres, which are nearly, though not
completely circular, but so arranged as to constitute a cylinder.
These fibres may be separated from each other so as to form
lamina, which have been considered as different coats of the
arteries ; but there is no arrangement of them which composes
regular distinct strata. The coats of arteries may, therefore,
be separated into a greater or smaller number of lamina, accord-
ing to the thickness of these lamina.

The fibres which compose these lamina appear to be united
to each other in a way which readily allows of their separation,

k

THE MUSCULARITY OF ARTERIES. 211

at the same time that they form a firm texture. Although
arteries thus appear essentially different from muscles in their
hardness and their elasticity, as well as in their 'general texture,
they are considered, by a great majority of anatomists, as
partaking more or less of a muscular structure.

In the human subject their structure is very difficult of
demonstration, and great differences exist in the accounts which
are given of it, even by anatomists who agree in the general
sentiment that the arteries are muscular.

Thus, Haller believed that muscular fibres were most abun-
dant in the large arteries, while J. Hunter thought the reverse.

Hunter appears to have investigated this subject with great
attention, and supposed the muscular substance, in the compo-
sition of arteries, to be interior, and the elastic niatter exterior ;
that in large arteries this muscular substance is very small in
quantity, and gradually increases in proportion as the artery
diminishes in size. He, however, observes, that he 7iever
could discover the direction of the muscular Jibres.*

When the great talents of Mr. Hunter as an anatomist are
considered, this circumstance cannot fail to excite a belief that
the existence of these fibres is not certain : and if to this be
added the fact, that even the red-colored substance of the
arteries is elastic, and in that respect different from muscular
substance, the reasons for doubting must be increased.

Bichat appears to have entertained very strong doubts on the
subject ; but he stands almost alone ; for a large number both
of the preceding and contemporary anatomists, seem to have
adopted the sentiment, that the arteries have a muscular
structure.

The student of anatomy can very easily examine this
subject himself, by separating the coats of arteries into different
lamina ; and by viewing the edges of the transverse and
longitudinal sections of those vessels. While thus engaged
with this question, he will read with great advantage what has
been written upon it by Mr. Hunter, in his treatise on the
blood, &;c., (see chapter second, section 3.) Bichat ought also
* Treatise on the Blood, &c., vol. i. p. 113. Bradford's edition.

212 PROOFS OF THE IRRITABILITY OF THE ARTERIES.

to be read upon this subject, which he has discussed in his
Anatomic Gcnerale — Sijstcme Vasculaire a Sang Rouge,
article Troisieme, &c. ; and also in his Traite des Membranes
article Sixieme.

The belief of the irritability of arteries does not, however,
rest upon the appearance of their fibres.

1. It is asserted by very respectable authors,* that they have
been made to contract by the application of mechanical and of
chemical irritation, and also of the electric and galvanic power.

2. A partial or local action of arteries is often produced by
the local application of heat and rubefacients, as has been
already observed.

3. Arterial action is often suspended in a particular part by
the application of cold. It has also been observed that the arte-
ries have for a short time ceased to pulsate in cases of extreme
contusion and laceration of the limbs.f

4. When arteries are divided transversely in living animals,
they often contract so as to close completely the orifice made by
the division.

5. In a horse, bled to death, it was ascertained by Mr. Hun-
ter, that the transverse diameter of the arteries was diminished
to a degree that could not be explained by their elasticity. He
also found that, after death, the arteries, especially those of the
smaller size, are generally in a state of contraction, which is
orreater than can be explained by their elasticity : for if they
are distended mechanically, they do not contract again to their
former size, but continue of a larger diameter than they were
before the distension ; although their elasticity may act so as
to restore a very considerable degree of the contraction observed
at death.

The contraction, which is thus done away by distention,
Mr. Hunter supposed to have been produced by muscular

* See Soemmering on the Structure of the Human body, vol. iv. German
edition, Dr. Jones on the process employed by nature for suppressing
Hemorrhoge, Ace.

t This local suspension of arterial motion by cold, Ace, applied locally, is
very difficult to explain: as the action of the heart and the elasticity of the
arteries appear sufficient to account for the pulsation of the large arteries.

k

GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 213

fibres : for if it had been dependent on elasticity, it must have
reappeared when the distending power was withdrawn.

It therefore seems certain, that the arteries have a power of
contraction different from that which depends upon elasticity ;
but whether this depend upon muscular fibres superadded to
them, or upon an irritable quality in the ordinary elastic fibres
of blood-vessels, is a question which is not perhaps completely
decided.

Fig. 173.* — The middle coat of the

arteries is composed of flat
fibres and bundles of fibres,
which surround the vessel in
a circular direction. They
are now generally believed
to be not muscular in their
structure, and do not exist
in veins. In the ox and the
elephant, they are particu-
larly well developed, in both
of which I have examined
them with attention, but
without discovering any evidence of muscularity in their com-
position. Berzelius has shown that the fibres of the elastic
coats of the arteries differ chemically from those of the muscles.
Muscular substance is soft and lax, and contains nearly three-
fourths iis weight of water, and has the same chemical proper-
ties as tlie fibrine of the blood. The substance of the arterial
coat is dry and contains no fibrine, and Dr. Hodgkin has
observed that its fibres do not present the transverse striae seen
on the muscular fibre. The arteries are eminently elastic, and
to this they owe their property of contracticfh, when they have
been distended, beyond their usual dimension. It is by virtue
of this elasticity also, that the arteries retain their tubular form
after death, when they are emptied of blood. The reaction of

* Elastic tissue from the outer part of tlie middle fibrous coat of the aorta,
as it appears when magnified 300 diameters. The intertangled fibres and
elongated cells common to the elastic tissue are well shown.

214 GENERAL OBSERVATIONS ON THE ARTERIES.

this coat during the intervals of the heart's action, ^also con-
tributes to render the flow of blood more uniform. — *

The motion of the blood in the arteries appears to depend,

1st, Upon the impulse given to it by the action of the heart.

2dly, Upon the elasticity of the arteries, in consequence of
which they first give way to the blood impelled into them, and
then react upon it ; and

3dly, Upon the power of contraction in the arteries, or their
irritability.

In the larger arteries the blood seems to move as it would
through an inanimate elastic tube, in consequence of the impulse
given by the heart, and kept up by the arteries themselves. In
the smaller vessels it seems probable that the motion of the
blood depends in a considerable degree upon the contraction
which arises from their irritability.

The obvious effect of the elasticity of the arteries is to resist
distention and elongation, and to contract the artery to its
natural state, when the distending or elongating cause ceases to
act. But it must also resist the contraction induced by the mus-
cular fibres, and restore the artery to its natural size when the
muscular fibres cease to act after contracting it, as has been
observed by Mr. Hunter.

It seems probable that all the fibres of which the artery con-
sists are nearly, but not completely circular ; for it is not certain
that there are any longitudinal fibres in the structure of an
artery.

The internal coat of these vessels is very smooth, but
extremely dense and firm ; and seems to be rendered moist and
flexible by an exudation on its surface. It adheres very closely
to the contiguous §bres of the coat exterior to it, but may be
very readily peeled off from them. It is of a whitish color,
and, like the fibrous structure of the artery, is very elastic.
Like that substance, also, it is easily torn or broken ; and when
ligatures have been applied to arteries, it has often been
observed that the fibrous structure, and the internal coat have

* Weber's Hildebrandt's Anatomie, tome iii. p. 68. — p.

GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 215

been separated while this external cellular coat has remained
entire.

The arteries are supplied with their proper blood-vessels and
lymphatics ; (i)asa vasorum.) It is to be observed, that these
blood-vessels are not derived from the artery on which they run,
but from the contiguous vessels.

These vessels have nerves also, which are rather small in size,
when compared with those which go to other parts.

Arteries appear to have a cylindrical form, for no diminution
of diameter is observable in those portions of them which send
off no ramifications.

When an artery ramifies, the area of the different branches
exceeds considerably that of the main trunk. Upon this prin-
ciple, the aorta and its branches have been compared to a cone,
the basis of which is formed by the branches, and the apex by
the trunk.*

The transverse section of an artery is circular.

There are no valves in the arteries, except those of the ori-
fices of the aorta and the pulmonary artery, at the heart. The
valves of the pulmonary artery have been described in vol. i.
p. 509, and those of the aorta have an exact resemblance to
them, but are rather larger.

The course of the arteries throughout the body is obviously
calculated to prevent their exposure to pressure, or to great
extension from the flexure of the articulations by which they
pass. With this view they sometimes proceed in a winding
direction ; and when they pass over parts which are subject to
great distension or enlargement, as the cheeks, they often
meander ; and, therefore, their length may be increased by
straightening, without stretching them.

Their course appears sometimes to have been calculated to
lessen the force of the blood, as is the case with the Internal
Carotid and the Vertebral arteries.

In the trunk of the body the branches of arteries generally

* According to Brussiere the relation of the branches of the aorta to its
trunk is as 25 lo 16 ; Helvetius reckons the orifice of the aorta in comparison
with its branches as 64 to 71. Lassus. — h.

216 GENERAL REMARKS UPON THE HEART.

form obtuse angles with the trunks from which they proceed.
In the limbs these angles are acute.

The communication of arteries with each other is termed
Anastomosis. In some instances, two branches which proceed
in a course nearly similar, unite with an acute angle, and form
one common trunk. Sometimes a transverse branch runs
from one to the other, so as to form a right angle with each.
In other cases, the two anastomosing branches form an arch, or
portion of a circle, from which many branches go off.

By successive ramifications, arteries gradually diminish in
size, until they are finally extremely small.

The small arteries do not carry red blood, their diameters
being smaller than those of the red particles of that fluid, the
serous or aqueous part of the blood can, therefore, only pass
through them.

Many of the arteries which carry red blood, and of the
last mentioned serous arteries, terminate in veins, which
are in some respects, a continuation of the tube reflected back-
wards.*

Position of the Heart.

— The heart is situated mainly between the sternum and
spine ; its left ventricle is placed immediately behind and to
the inner side of the left nipple ; its base is horizontal, and
nearly opposite a line drawn horizontally from the junction of
the cartilage of the third rib with the sternum. The right
auricle is placed so that its free border is a little to the right
side of the sternum, between the junction of the third and
fourth costal cartilages with that bone. The flattened surface

* Malpighi and Leuenhoek declare, that by the aid of a microscope they
have seen arteries terminating in the veins. Haller advances formally his own
experience in support of his assertion. Other anatomists have seen, that in
blowing into an artery, the air passed into the corresponding veins. Never-
theless, Duverney and some others say, that a particular substance is inter-
posed between the extremities of these vessels. Ruysch, in his Thesaurus
Anatomicus, VI. No. 73, says, in repletione arteriarum, replentur et plurimum
quosque venae, et vice versa, ita ut impossible videatur prsecise dicere quomodo
res se habeat. Discours sur I'Anat. — h.

DIMENSIONS OF THE HEART. 217

of ihe heart below, rests upon the bottom of the pericardium,
covering the cordiform tendon of the diaphragm. The apex of
the heart, formed by the extremity of the left ventricle, is nearly
opposite the junction of the fifth rib with its cartilage at the dis-
tance of two or three inches from the sternum.

Dimensions of the Heart.

— The heart was said by Laennec, to be of the size of the closed
fist of the same subject. But this is a rule upon which little
reliance can be placed. It was found by very accurate ob-
servations made by M. Bizot,* on one hundred and fifty-
six subjects of ages varying from one to eighty — that the
heart has no natural limit in regard to size, but increases
indefinitely without being diseased, according to the age of the
subject. After fifty years, however, the growth is so slow, as
to be scarcely noticeable, except it become diseased.
— In 18 subjects between the ages of 16 and 29, on the average
the length was 42 lines; breadth 46; thickness, 17i. In 19,
between the ages of 50 and 79, the average length was 46 lines ;
breadth 53 ; thickness 18j. In females upon the average at the
same ages, the dimensions were each about three lines less.
The dimensions of the heart are directly in relation to the
breadth of the shoulders, and by careful observations made upon
sixty-four subjects, consisting of nearly an equal number of each
sex, it was found by M. Bizot, that in individuals of middle
stature and under, that the heart was absolutely of greater
size, than in those who were distinguished for their tallness.
— It has been asserted by Andral,f that the four cavities of the
heart, in their natural and healthy state, are as near as may be
of equal dimensions ; and by M. Beclard,J that the right ven-
tricle as age advances, becomes enlarged in a greater proportion
than the left.

* Mem. de la Societe Med. d'Observation de Paris, 1836. —

f Diet, de Med. nouv. ed. torn. viii. —

I Lieutaud and Sabatier, thought the cavities of the ventricles were equal in
the healthy state, and that the cavity of the right was enlarged by the respira-
tory struggles at the time of death. It has been proved, however, long since,
by Legallois, that the mode of death has no effect in altering the form of the
heart. — f.

VOL. II. 19

218 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.

— The researches of the same careful observer has shown, that
the right ventricle as well as right auricle,* and right auriculo-
ventricular orifice and pulmonary artery, are larger than the
corresponding parts of the left side, at all the different stages of
life. The mean dimensions in men, taken from many indivi-
duals, between the ages of 15 and 79, are —

Left ventricle, length, 34, lines, breadth, 54 lines.

Right " 37 " " 82 "

— Mean thickness of the ventricles between same ages.f
Left at base, 4i lines, middle, 5 lines, near its point, 4 lines.
Right " 2 nearly, " li " " 1 "

— Mean circumferences of the auriculo-ventricular orifices.
Of the left, (between the same ages, 16 to 79,) 45i lines.
Of the right, " " 54 "

— Mean circumference of the orifice of the aorta, and pulmo-
nary arteries, taken opposite the free border of the sigmoid
valves.

Of the aorta, (between the same ages,) 31i lines.

Of the pulmonary artery, 32^J "

— The coronary arteries undergo a development in size, exactly
in harmony with that of the heart. In the foetus, where the
thickness of both ventricles seems equal, there is no difference
in the size of the coronary arteries. But as the walls increase
in thickness, especially that of the left ventricle, these arteries
enlarge, and in particular the left. Boyer, H. Cloquet and
others, have fallen into error, in stating that the calibre of the
left coronary artery is less than the right.

* The comparative measurements of the auricles have not been taken. — f.

f The thickness of the septum ventriculorum is about the same as that of
the left ventricle, and undergoes the same modifications in respect to age. The
columna? carnese are not included in the measurement of the thickness of the
ventricle. — p.

J In the latter ages of life, the aorta increases in its dimensions so as to
exceed in circumference at its orifice, the pulmonary artery. This is in all
probability owing to the frequency of the morbid alterations of the aorta in old
men, in which the middle coat of the vessel loses its elasticity and becomes
dilated : while alterations of the pulmonary artery are very rare, even at the
most advanced stages of life. — p.

MEASUKEMENT OF THE HEART. 219

— Circumference of the coronary arteries at their origin.
General mean of the left in man, 5i lines.

" " right " 4i "

— The thickness of the ventricles, which are at birth nearly the
same, go on increasing, as life advances, though not in equal
proportions. The walls of the right ventricle are arrested in the
healthy state at their maximum of thickness, much sooner than
those of the left.

— The volume of the heart, and the greater or less capacity of
the right ventricle, have, in the healthy state, but little influence
over the thickness of its walls. The thickness, however, is
found slightly increased in advanced age. That of the left
ventricle increases without cessation. Hence, the assertion of
Andral and others, that the natural thickness of the walls of
the left ventricle is three or four times as great as that of the
right, is applicable only in advanced life.

— Professor Cruveilhier has asserted, that the thickness of the
ventricles beyond which only hypertrophy is to be considered
as existing, are seven to eight lines for the left, and four to five
lines for the right. The numerous and careful measurements
of M. Bisot, have, however, proved this standard to be exces-
sive, and that a thickness of seven lines of the left ventricles in
man, and six in women, would be a commencement of hyper-
trophy, even in the last stages of life ; and that the maximum of
thickness in the right ventricle, from 50 to 79 years, in man is
but 2,^th lines, and but l\ line in woman.

— Mean dimensions of the aorta, taken from a large number of
subjects at seven different points.
— One line on the cardiac side of the arteria innominata.

Men. Women.

General mean of circum-
ference, from 16 to 79, 33 lines. Do. from 16 to 89, 31 lines.

Near the left subclavian,

general mean, 33 " " 24 "

Opposite the remains of

the ductus arteriosus, 25 " " 23 "

Above the cceliac artery, 22i " " 20^ "

220 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.

— In all the measurements of the heart and other portions o(
the vascular system, we shall speak only of the healthy or nor-
mal measurements at the different stages of life.

Below the renal arteries, 17^ lines. In women 16 lines.

Near its bifurcation, 17 " do. 15 "

— The diameter of the aorta is greater, as will be seen by these
measurements, both in the male and female, near the origin of
the innominata, than at its connexion with the heart. It is less
near the left subclavian, diminishes considerably near the
coeliac and renal branches, and from thence to its termination,
scarcely varies at all. These results also disprove the assertion
of Richerand, that the descending aorta and iliac arteries,* are
larger in woman than in man. In woman, the internal iliacs
continue to increase in size even after the age at which the
function of reproduction has ceased. In fact, the whole aortic
trunk, like the heart, continues to increase gradually in size in
both sexes, up to the most advanced period of life, and like the
heart also, as it increases in calibre, has the thickness of its walls
likewise augmented.!

— The branches of the aorta both in regard to size and age,
undergo corresponding changes with the aorta itself. Of the
abdominal branches, the superior mesenteric is the largest of
all ; the next in size are the renal and coeliac ; the two latter
being nearly of the same size. Hence, each kidney receives
as much arterial blood as the liver, spleen, and stomach togeth-
er. This would seem to be rendered appropriate by the relative
functions of the organs ; that of the kidneys being to depu-
rate the mass of blood of its saline and many other noxious
principles.

— Of all the organs in the body, the heart and arteries are the
only ones which constantly increase in dimensions; in old
age the muscles become atrophied, the skin shrivels, and even
the skeleton diminishes in bulk.

* See (further on) measurement of iliac.-
I See Richerand's Physiology, 10th edit.

FORM OF THE ARTERIES. 221

Form of the Arteries.

— Bicliat and Rlcherand have considered every arterial tube
to be evenly cylindrical, the diameter of it only being
diminished when branches were sent off. Beclard believed
that they had the form of a truncated cone, with the base
turned towards the heart, some of them, as the carotids for
example, being enlarged at the place of division. Others be-
lieve with Professor Horner,* " that the arterial system in its
general configuration may be compared to a tree, the trunk of
which is attached to the heart, and which, by a continued suc-
cession of divisions and subdivisions reaches to every part of
the body. There are no means of, estimating rigidly the collec-
tive area of the branches in proportion to that of the trunk ;
but a little observation on the size of the primitive branches,
will satisfy one of a great excess on the part of the latter, and
as the rule is maintained throughout, there must finally be an
immense disproportion. We have then reason to believe, that
if all the branches were assembled into a single cavity, this
cavity would be somewhat like a cone, the apex of which
would be next the heart. The same rule holds in regard to
the venous system, it being observed, however, that the latter
has two trunks connected with the heart instead of one. The
general rule is therefore established throughout the vascular
system, that the collective area of the branches is always
greater than that of the trunk from which they proceed. By
the same rule the circulation in the branches must be more
languid than in the parent trunks, as this circulation is retarded
both by additional friction, and by having to fill up a larger
canal."*

— Nevertheless, Professor Horner, gives a computation made
by Mr. Erskine Hazard from actual measurement of the arte-
ries, from which it appears, that in many of them" at least, the
area of the large trunks before subdivision is greater than that
of their divided branches united, and consequently that the

* A Treatise on General and Special Anatomy, vol. ii. p. 155, by W. E.
Homer, Prof, of Anat. University Penn., &.c. &c. ; fourth edition. —

19*

22^ GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.

blood must flow faster through the branches than through the
primitive trunk, as the same quantity of blood must be disposed
of in the same space of time ; and that by this means, friction
is reduced, as there is less surface of the vessels exposed to the
passing of the blood, and the force of the heart's action is
continued much farther through the system.
— This manifest discrepancy among anatomists of high reputa-
tion, is explicable by the facts made known from careful mea-
surement by M. Bizot ; viz. that all the different modes of form
above specified, are met with in the arterial system, and that
each artery, so to speak, has its peculiar and constant form
in a healthy state ; the corresponding arteries of the two
sides of the body, being analogous in shape. To establish the
truth in regard to these points, this writer measured 2,162
arteries, in addition to the measurements of the aorta already
given.* All the modes of formation of the arteries he reduces
to the five following.

1. A cone, the base of which is directed towards the heart,
met with 39 times in the 100.

2. Two truncated cones opposed by their truncated summit, •
met with 28 times in the 100.

3. A cone with its summit directed towards the heart, met
with 14 times in the 100.

4. A perfect cylinder, met with 12 times in the 100.

5. Two truncated cones opposed by their base, met with five
times in the 100.

— It is seen by this statement that, contrary to the opinion of
most anatomists, the perfect cylinder is one of the rarest forms.
The arteria innominata belongs to the second class, or in
other words, forms a tube narrowed in its middle, in nearly
one half of the cases in which it was examined. The primitive
carotid belonged to the same, in more than three-fourths ; whilst
the same arteries but twice in one hundred and thirty-six in-
stances presented the form of a cylinder.
— The brachial, primitive and external iliacs, were found to

* It has been computed that the blood flows 5,233 times slower in the
capillaries than in the aorta. — p.

THE CAPILLARIES. 223

belong to the second class in about one-third of the cases ex-
amined. In the other arteries that form is much more rare. The
vessels which present the cylindrical form most frequently, are
the radial and crural arteries. The first form, that of a truncated
cone, with the base to the heart, is by far most frequent in the
arteries of the limbs. The popliteal, however, always presents
the fifth form, that of two truncated cones opposed by their
basis, or in other words is expanded in its middle at the place
where popliteal aneurism usually occurs.

Of the Capillaries.

— The extreme ramifications of the arteries, constitute the
capillary blood-vessels, which are intermediate to, and form
the connexion between the arteries and veins, and may be
considered as the radicles of the latter vessels. The extreme
minuteness and delicacy of structure of the capillary vessels,
are too great to admit of any very rigid scrutiny into the struc-
ture of their walls, but it is considered probable that the internal
coat of the arteries, is extended through them, so as to be con-
tinuous with that of the veins. The capillary vessels, were at
one time considered as having other terminations besides those
which connected them with the arteries, on one hand, and the
veins on the other : some were considered, as opening directly
into, and thus forming the secretory ducts of the different glands;
others as ending in a manner nearly similar, in order to form an
imaginary system of vessels, called the exhalents, in the skin
and the different serous and mucous membranes ; and others,
according to Lond and Lepelletier de la Sarthe, as terminating
in the midst of the different tissues, so as to allow the mole-
cules of blood to escape naked among the organized parts, for
the purposes of nutrition. It is now, however, generally admit-
ted, that the capillaries have no termination but by their anas-
tomoses with each other, and their communication with the arte-
ries and veins ; that all the fluids which pass from them, for
the purposes of nutrition, secretion, or exhalation, permeate in
some manner their delicate coats, by an action, somewhat like
the exosmosis of Dutrochet.

224 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.

— The direct communication between the arteries and veins,
is readily shown by the facility with which the veins may be
distended, by injection of the arteries of the extremities with
mercury. In many of the viscera, also, it is not unusual to fill
some of the veins, when distending the arteries with size
injection.

— Some anatomists (vide note, p. 216) assert that they have
in the human subject, been able to trace with the microscope,
the direct continuity of the arteries with the veins. This may
be done more readily in the inferior animals, especially in the
reptilia, where the globules of the blood are three or four times
larger than those of man.

— In the dissection of two large serpents, a python from South
America, and a boa constrictor from the East Indies, made jointly
by the late Dr. John P. Hopkinson and myself, an account of
which was read before the American Philosophical Society in
1833, we were enabled by the aid of the mercurial pipe and
column, to pass quicksilver, in many instances, from a branch of
the aorta, into the capillary' arteries of the peritoneal investment
of the oviducts. Then by gently pushing forwards the minute
columns of mercury through these capillaries with the handle of
a scalpel, we found it to pass into the veins, and back again in
a retrograde direction to the vena cava. In these cases, the
capillary vessels when- distended with mercury, were very obvious
without the aid of a microscope. In the transparent parts of
animals, as in the mesentery, in the fins of some fishes, and in the
web of a frog's foot, or in a frog's tongue, the microscope exhibits
very clearly the capillary system of vessels, as well as the series
of blood globules which pass through them from the arteries to
the veins.

— Fig. 174, is a representation, after Thomson,* of the appear-
ance of the capillary circulation in the web of a frog's foot.
The arrows indicate the course of the blood, the globules of
which are seen in these vessels arranged in a linear series.
— Marshall Hall, considers the capillary system as a distinct
portion, reticular in its structure, the branches anastomosing

* Circulation — Cyclop, of Anat. and Physiology. —

THE CAPILLARIES.

225

and separating from each other, and yet unlike either the arte-
ries or veins, retaining always the same diameter. In the lungs
he considers this system particularly well developed ; and that
the walls of the ultimate branches of the arteries and veins are
abruptly terminated, and appear cribriform under the microscope,
when they communicate with or divide into the capillary arteries
and veins.

Fio-. 174.

— The delicate capillary vessels of the lungs are inclosed in
the mucous membrane, forming the bronchial cells. The
mucous membrane of these cells being derived from the
bronchia, is of course continuous throughout the lungs, and
may be regarded as a delicate membrane filled with a net-work
of capillary vessels, formed into cells for the mere purpose of
allowing an extensive surface to be compressed into a small
space : upon one surface of this membrane, the pulmonary
vessels maintain a stream of blood, divided into currents of the
minutest size ; and on the other, air is admitted through the
bronchia, the oxygen of which acts upon the particles of blood
in their most divided state.

— The pulmonary or lesser circulation, (which is conducted
through the pulmonary arteries and veins,) would be perfectly
isolated from the greater or systemic, (that of the aorta and vena

'226 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.

cava,) were it not that the bronchial arteries anastomose in the
lungs with the smaller branches of the pulmonary.
— -The capillary vessels are so abundant, that the width of the
spaces left between them are believed in man to be less than the
diameter of the vessels themselves. The diameter of the ca-
pillaries, which has been taken by the aid of the microscope after
the vessels had been minutely injected, has been found to vary
in different parts of the body, It appears, however, to be
uniform in the vessels of the same organ, but varies in different
places from the jg^g to jJ^g parts of an inch. In the brain, the
retina and villi, they are even said to measure only from jjgg to
losoo* '^^® circulation through these vessels goes on slowly, and
in an even stream. It appears from microscopical observations,
that the current flows more rapidly in the centre, and dimin-
ishes gradually toward the periphery of the vessel, so that there
is formed on its inner wall, what has been called the motionless
layer of blood. By this arrangement the plastic fluid of the
blood, (not the blood globules,) is arrested by adhesion, as it
were, on the inner surface of the vessel, for the purposes of
exosmosis, or transudation into the surrounding substance, which
it is to nourish. The mean of the measurement of the capil-
laries, according to Miiller, is between the glggth and i|5[,th part
of an inch. No other tubes in the body are so minute as the
capillary vessels, not even those of the kidney or testicle.

Action of the Heart and Arteries.

— The heart of an adult man, in the middle period of life, con-
tracts from seventy to seventy-6ve times a minute. At each
pulsation it is calculated that about two ounces of blood is eject-
ed. The whole amount of blood in the human body has been
variously estimated, and it is perhaps impossible to arrive at a
very accurate conclusion upon the subject; there is certainly a
larger amount in the body than is usually at one time in active
circulation, a part of it moving slowly, or remaining stagnant for
a time, in the capillaries of some portions of the body. Accord-
ing to Wrisberg, one woman lost by a fatal flooding, 26 lbs. of
blood ; and in another plethoric woman, who was beheaded,

ACTION AND SOUNDS OF THE HEART. 227

24 were collected. Herbst* has calculated that there is usually
about ten lbs. of blood in free circulation in the human body.
It may, therefore, be admitted with some certainty, that the cir-
culation of the entire mass of floating blood may take place in
from one to two minutes.

— The frequency of the heart's action diminishes gradually from
the commencement to the end of life, thus :f

In the embryo, the number of beats in a minute is 150

Just after birth, ... - 130 to 140

During the first year, - - - 115 to 130

During the second year, - - - 100 to 115

During the third year, - - 90 to 100

About the seventh year, - - - 85 to 90

About the fourteenth year, - - 80 to 85

In the middle period of life, - - 70 to 75

In old age, - - - - 50 to 65

— In persons of sanguine temperament the heart beats some-
what more frequently than in those of the phlegmatic, and in
the female sex more frequently than in the male. The number
of pulsations in the minute varies very much in different animals ;
it is as low as 40 in the horse.

— Tiie contraction (systole) of the heart is its only active state ;
its dilatation (diastole) is effected passively during the moment
of repose when the fibres are relaxed, by the blood which is
poured into its cavities from the contiguous veins. Dupuy, a
distinguished veterinary surgeon of Alfort, found, on intro-
ducing his hand into the abdomen of a living horse, that the
vena cava ascendens became turgid during the systole of the
heart ; and flaccid during the diastole, in consequence of the
blood rushing from the veins into the cavities of the heart.
The apex of the heart is closely in contact with the ribs, from
which it is separated only by the pericardium. The body of
the heart is also near the inner surface of the ribs and sternum,
for there is nothing intervening beside the pericardium but a

* Herbst, De Sang. Quant, etc. Goettingen, 1822.

f Mailer's Physiology, (Bennet's translation,) p. 171, vol. i.

228 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.

thin prolongation of the pulmonary tissue. The impulse of
the heart, pulsis cordis, is owing to the shock communicated
to the walls of the thorax in the neighborhood of the fifth and
sixth ribs, and which is believed to take place during contrac-
tion, by the apex of the heart being tilted upwards and for-
wards. This impulse must not be confounded with the arterial
pulse or proper sounds of the heart, though it is synchronous
with the first sound.

— The sou7ids of the heart are twofold ; the first sound and the
stronger, is produced by the quick successive contraction of the
auricles and ventricles. The second sound, as results from the
recent observations of Dr. Carswell, is produced by the sudden
closing under the elastic reaction of the arteries, of the semi-
lunar valves of the aorta and pulmonary artery. The interval
between these sounds is very slight ; it is calculated by Miiller
to be about the fifth part of a second.

— The pause which intervenes between the termination of the
second and the recommencement of the first sound, is nearly equal
to the period which elapses between the pulsations of the arteries.

Of the Pulse.

— The blood not being able to escape from the arteries into the
veins through the capillaries, as quickly as it is injected into
the former by the heart, it necessarily exerts a pressure on the
elastic coat, which yields both in the direction of its length and
its diameter. This elastic yielding constitutes the arterial throb
or pulse. This pulsation is not produced, however, directly
by the two ounces of blood injected that moment from the
heart ; but indirectly, in consequence of these two ounces being
injected into the base of the column of blood with which the
aortic system is filled so as to transmit the shock through
the whole arterial tubes, driving out at the other extremity a
corresponding quantity into the veins. The impulse of the
heart is transmitted by the oscillation of the particles, along the
vessels, (precisely as takes place when a shock is communicated
to a column of water in a hose,) and this constitutes the pulse.
The elastic force of the arteries when distended is very familiar

GENERAL ANATOMY OF THE VEINS. 229

to those who are in the habit of injecting them for anatomical
study. By partially filling the vessels with a thin fluid and
then throwing in more fluid per saltum, we may readily produce
a sort of artificial pulse. —

Of the Veins.

These tubes, which return to the heart the blood carried
from it by the arteries, are more numerous than the arteries, and
often are larger in diameter.

They generally accompany the arteries, and very often two
v^eins are found with one artery. These are called the vente
comites.

— Accompanying the larger arteries of the body, we usually
find but one attendant vein of proportionate size. It is the
smaller arteries, and especially those of the extremities, that
have generally running by their sides, and mostly in very close
connection, two venous trunks (vena comites) all of which are
invested in one common sheath. —

In addition to these last mentioned veins, which may also be
called deep-seated, there are many subcutaneous veins which
appear on almost every part of the surface of the body.
— There is a third division of the venous system known under
the name of sinuses, found in the cranium, the diploe and cells
of the bones, and in the substance of the uterus. These are
all lined in their interior by the common lining membrane of
the veins. But they differ from the other veins in regard to
their outer tunic, which is formed of the dura mater in the
cranium, of the cellular lining membrane found in the cells of
the bones ; and in the uterus apparently of the substance of
that organ. —

The capacity of all the veins is much greater than that of
all the arteries.

Those subcutaneous veins which are of considerable size,

communicate very freely with each other, and also with the

deep-seated veins. — They are found just below the skin in the

layers of the superficial fascia, which latter membrane they

VOL. II. 20

230 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM.

pierce in convenient positions to discharge their contents in the
deeper seated veins. —

The trunks of the veins, in those places where no branches
go off, are generally cylindrical. There are, however, some
exceptions, in which these vessels are irregularly dilated, as
sometimes happens in the case of the internal jugular vein. It
is, however, not easy to determine from the appearance of
veins injected after death, respecting their situation during life,
as their coats are very yielding ; and it is very probable that
they are, therefore, preternaturally dilated by the injection.

Veins, directly or indirectly, originate from the termination
of arteries : but they do not pulsate as the arteries do, because
the impulse given to the blood by the heart is very much
diminished in consequence of the great diminution of the size of
the vessels through which the blood has passed.

In some cases, however, when blood flows from an opened
vein, the extent of its projection is alternately increased and
diminished, in quick succession, as if it were influenced by the
pulsation of the heart.

The Coats of Veins differ considerably from those of
Arteries, — for they are thinner, and so much less Jirm, that
veins, unlike arteries, collapse when they are empty.

They consist of a dense elastic substance, the fibres of which
are much less distinct than those of arteries, but some of them
are to be seen in a longitudinal direction. These fibres can he
made to contract by local irritation ; for if a vein be laid bare
in a living animal, and then punctured, it will often contract so
as to diminish its diameter very considerably, although no blood
shall have escaped from the punctures.

Next to the elastic substance is the internal coat, which is

smooth and polished. It is separated from the substance exterior

to it with difficulty, although it may be taken from it very easily

in the vena cava.*

* The microscopical observers have found considerable analogy in the
structure of the arteries and veins, though their opinions vary in some respects.
The arteries are described by Henle as being composed of six different layers.
1. The innermost epithelial lining. 2. A striated or fenestrated coat. 3. A
granular fibrous layer. 4. The middle elastic or muscular coat, composed of

THE VEINS. 231

This internal coat is more ostensible than the internal coat of
arteries, and is not, like the latter, disposed to ossification. It
is frequently so arranged as to form valves, which are plaits or
folds, of a semilunar form, that project from the surfaces into
the cavities of these vessels.*

Two of these valves are generally placed opposite to each
other; and, when raised up, they form a septum in the cylin-
drical cavity of the vessel. The septum, thus composed, is
concave towards the heart, (see fig. 172, p. 208.)

The valves have a great effect in preventing the contents of
the veins from moving in a retrograde course : they therefore
necessarily modify the effects of lateral pressure, in such a
manner, that it propels the blood forward, or towards the
heart.

These valves are generally found in the veins of the muscular
parts of the body, especially in those of the extremities. They
are not found in those veins which are in the cavities of the
body, nor in the internal jugulars. They are placed at unequal
distances from each other.

The coats of the veins are somewhat transparent; and there-
fore those veins which are subcutaneous have a bluish aspect,
which is derived from the color of the blood they contain.

The color of the blood in the veins is different from that in
the arteries, being of a darker red.

The situation and arrangement of the large trunks of veins
are much alike in different subjects ; but the branches, especially
those which are subcutaneous, are very variable in their situa-
tions.— The situation of the deeper seated veins of the extremi-
ties— the venae comites and the sinuses are subject to little

circular fibres. 5. A coat of genuine elastic tissue. 6. The external cellular
lining. The veins, though thinner much in their walls, present the same struc-
ture, the true elastic coat only being absent. The valves of the veins consist
of a fibrous membrane covered by the epithelium, and are not mere duplica-
tures of the lining membrane. — p.

* The valves of the veins were first described by Charles Etienne of Paris,
in 1546. In 1547, Amaius, a Portuguese, saw at Ferrara, those at the mouth
of the vena azygos. Sylvius, of Paris, announced them about the same time
in the jugular, brachial and crural veins. Fabricus ab Aquapendente claims
the discovery for himself in 1574. Lassus.

232 THE BLOOD.

variation. There are three grand divisions of the venous sys-
tem, which in a physiological point of view, are deserving of
particular notice. —

— 1st. The pulmonary venous system, by which the dark or
venous blood, after it has been restored to its arterial hue is
returned again to the left ventricle of the heart, through the
pulmonary veins. Here we have the apparent anomaly, of
veins carrying arterial blood, and of an artery — the pulmonary,
which transmits venous.

— 2d. The systemic venous system, or that of which the roots
are formed in the two venae cavae.

— 3d. The portal venous system. In this we have the singular
instance of a vein which has its origin, like the rest, from
capillary branches, branching again like an artery, so as to form
a second set of capillary vessels in the substance of the liver,
from which arises a new venous trunk, called the hepatic
vein. If we except the placental circulation of the child, no
other instance of a similar distribution of the veins appears
in the human body. —

Of the Blood.

The blood of a healthy person indicates a tendency to coag-
ulate very soon after it is discharged from the vessels which
naturally contain it, although it is perfectly fluid in those
vessels.

If it remain at rest, after it is drawn from the vessels, it soon
coagulates into a solid mass, of a soft texture. From this solid
mass a fluid is soon observed to issue, which appears in very
small drops on almost every part of the surface. These drops
quickly increase and run together, and in a short time the fluid
surrounds the solid mass, and exceeds it in quantity.

The solid part which thus appears upon the spontaneous
separation of the blood, is denominated Crassamentum or
Cruor ; the fluid partis called Serum.

The substance which contains the red color of the blood
remains with the Crassamentum. The Serum, when it sepa-
rates without agitation, is free from the red color.

THE BLOOD. 233

The coloring matter may be separated completely from the
Grassametitum by washing it with water.

The blood, therefore, consists of three parts, namely ; the
Serum ; the substance which coagulates spontaneously
(Jibrine) ; and the Coloring Matter.

— If the blood be examined with the microscope in the
vessels of a transparent part, or immediately after it has flowed
from the body, it is seen to consist of small red particles or
globules, and a clear-colorless fluid. This fluid is the lymyha
or liquor sanguinis, and must not be confounded with the
serum, which separates from the crassamentum during coagula-
tion. It can be obtained free from the red globules, before coagu-
lation takes place, by filtering the blood of a frog or some other
animal, in which the red globules are so large as not to pass
through the pores of the filtering paper. The liquor sanguinis,
consists of the serum of the blood that holds the fibrine, which
is also colorless, in a state of solution. When the fibrine coagu-
lates, it encloses within it the red particles, and the watery
part of the blood (jseruni) is left, which holds the albumen in
solution. —

The Serum

Has a considerable degree of consistence, although it is much
thinner than blood. In its perfectly natural state, it is almost
transparent, and appears to be very lightly tinged with a
greenish yellow color; but it is very often impregnated with
a portion of bile, which is probably carried to the blood-vessels,
by the absorbents. It contains a large quantity of albumen,
or matter like the white of an egg. If heated to 140° of Fah-
renheit, it becomes opaque ; and when the heat is increased to
156° or 160,° it is firmly coagulated. It is also coagulated by
alcohol, by mineral acids, and by rennet.* It is proved by
chemists, that it contains a small quantity of pure soda. It
therefore changes several of the blue colors of vegetables to
green. It is also found to contain a similar quantity of the

* See Hewson, vol. i. 139. — I suspect that some particular management is
necessary in the use of rennet.

20*

234 THE BLOOD.

muriate and the phosphate of soda and the phosphate of lime.
These saline substances were discovered by diluting serum
with water, and exposing the mixture to heat, by which the
albumen was coagulated into flocculi ; these flocculi were sepa-
rated by filtration ; the liquor was then diminished by evapora-
tion, and the salts obtained from it by crystallization.

Serum likewise contains a portion of sulphur combined with
ammonia.

When it is exposed to a coagulating heat, a small portion of
it remains fluid.

This fluid portion has been supposed to contain a considera-
ble quantity of gelatine ; but it is contended by Mr. Brande,*
that Gelatine does not exist in the serum of the blood, and
that this portion consists of albumen combined with a propor-
tion of alkali.

It is also asserted by Dr. Bostock,f one of the later writers
on the subject, that the serosity of blood, (the term applied to
the last mentioned fluid,) contains no gelatine ; but that, with
a minute quantity of albumen, it consists of a large portion of
an animal matter, which is different either from gelatine or
albumen, being unlike either of them, in its chemical qualities.

The Crassamentum

Is rendered very different in its appearance, by the different
circumstances in which it may coagulate.

When the blood remains at rest immediately after it is drawn,
the crassamentum forms in it is a concrete substance, without
the smallest appearance of fibre in its composition. If the
blood be stirred with a rough stick, while it is flowing from an
animal, a large portion of it will concrete upon the stick in a
fibrous form, so as to resemble a mass of entangled thread, some
of the red coloring matter still adhering to it.

The crassamentum, in either of these forms, may be washed

* In his Researches on the Blood, communicated to the Royal Society of
London, in 1812, and republished in the Eclectic Repertory, for April, 1813.

f See his Observations on the Serum of the Blood, in the Medico-Chirurgical
Transactions, vol. ii, republished in the Eclectic Repertory, for October, 1812.

THE BLOOD. 235

perfectly white ; the red coloring matter passing completely
away with the water. In this state it appears* to have all the
chemical properties of the fibrous matter of muscular flesh. It
also resembles the gluten of vegetables, being soft and elastic.
The name fibrine is now generally applied to it.

If FIBRINE is washed and dried, its weight is very small
indeed when compared with that of the blood from which it has
been obtained. It is, therefore, probable that a considerable
proportion of the bulk of the crassainentum, as it forms sponta-
neously, depends upon the serum which exists in it, and can be
washed away.

The spontaneous coagulation of the blood, which appears to
depend principally upon the Fibrine, may be prevented by the
addition of several foreign substances to the blood, when it is
drawn. It is subject to great variations that depend upon the
state of the body at the time of bleeding ; and in some condi-
tions, it does not take place at all.f

In a majority of dead subjects the blood is found more or
less coagulated in the veins ; but in some subjects it is found
without coagulation. It is asserted that it does not coagulate
in subjects who have died suddenly, in consequence of anger,
lightning, or a blow on the stomach.

The Coloring Matter.

When the blood-vessels in the transparent parts of certain
living animals are examined with magnifying glasses, it appears
that the red color of the blood is owing to bodies of a globular
form, which are diffused through a transparent fluid. The
appearance of these bodies has been examined, with great atten-
tion, by many physiologists, since the publication of Leuenhoeck,
in the London Philosophical Transactions-!

* By the experiments of Mr. Charles Hatchett, published in the London Phi-
losophical Transactions for 1800.

f See an Inquiry into the Properties of the Blood, by the late William Hew-
son : and Experiments by his son^ T. T. Hewson, in the Eclectic Repertory,
Jan. 1811. See, also, a Treatise on the Blood, ice, by the late J. Hunter.

:|: Among the most distinguished of these observers were Father De la Torre,
Haller, Hewson, Fontana, Spallanzani, J. Hunter, Cavallo.

Some short accounts of Leuenhoeck's original observations on the Blood are

236 THE BLOOD.

Several of these gentlemen have described the appearance of
the blood very differently ; but Haller, Spallanzani and J.
Hunter agree that the figure of the red particles is globular.*
Hunter observes farther, that the red globules do not run into
each other as two globules of oil would do when divided by
water ; and he believes that they cannot unite. At the same
time they seem not to have the properties of a solid : for when
circulating in the vessels, they assume elliptical forms, adapting
themselves to the size of the vessels. They also excite no sen-
sation of solidity when touched.

They appear to be more heavy than the other parts of the
crassamentum : for in healthy blood the lower part of the mass
contains more of the coloring matter than the upper part ; and
in the blood of persons who labor under acute local inflamma-
tion, they often subside completely from the upper part; and
thus occasion what is called by Mr. Hewson the injlamniatory
crust, or size.

It has been observed by Mr. Hewson, and also by Mr. Hun-
ter, that the globules do not retain their form in every fluid.
They are said to be dissolved very quickly in water, and then
they form a fine clear red. Several of the neutral salts, when
dissolved in water, prevent the solution of the globules. Mr.
Hunter informs us, that the vitriolic acid, when greatly diluted,
does not dissolve them, &c. The muriatic acid, when three
times as strong as vinegar destroys their color without dis-
solving them, although when more diluted, it does dissolve them.

to be found in the Philosophical Transactions of London, for 1G64, in the fasci-
culi which are numbered 102 and 106. A more full description is contained in
Boerhaave's Academical Lectures on the Theory of Physic. See the section on
the nature of the blood.

The glasses of Father De la Torre were transmitted from Naples to the Koy-
al Society of London in 1765. They were accompanied by a letter from Sir F.
H. E. Stiles, to which are subjoined some observations by the Rev. Father
himself. The letter and the observations are published in the 55ih volume of
the Transactions of that society.

In the year 1798, Tiberius Cavallo published an Essay on the Medicinal Pro-
perties of Factitious Air, with an Appendix on the Nature of the Blood, in
which is contained a farther account of the glasses of De la Torre.

* I believe that this is also the opinion of Fontana. — In J. Hunter's work on
the blood there are some interesting observations on microscopical deceptions.
See the note commencing in page 39, Bradford's edition.

THE BLOOD.

237

— Hewson described ihe red globules as being flattened, and
was the first to discover distinctly, the dark spot in the centre,
formed by the central nucleus. Modern improvements in the
manner of using the microscope, have confirmed his views,
and shown that the globules of blood in different animals, are
always flattened, and that they vary in their outline, from the
elliptical to the circular form.

Fig. 175.* — In the mammalia, including man, they are circu-
lar disks ; that is, globules flattened upon the sides.
In birds, reptiles, and fishes, they are elliptical ; the
long diameter being twice that of the transverse.
In the globules of human blood, their thickness is
about one-fourth or one-fifth of their transverse
diameter. The size of the red globules varies very
much in difl^erent animals, and to some extent
among themselves, even in the same animal. But
in man and most other animals, the variation in
size, never amounts to a doubling of the diameter. The size
of the red globules in the amphibia, is greater than in any
other class of animals. The long diameter of the red globules
in the frog, is four times that of the circular diameter of those
of man. The diameter of the blood corpuscles in man have
been variously stated, from the sJootl^ to the jgggth part of an
English inch.
Fig. 176.f — In the centre of all the red particles there is
jj<l ^ a dark spot, which is elhptical in shape, in all
k^^sf^^^^ animals in which the general shape of the par-
jrjc, - tide is elliptical ; and round in those in which
the particles are circular and flattened. These

^^A^^p) spots or nuclei, when viewed with the light in
a particular situation, reflect it, and present the
appearance of holes, which at one time induced the belief, that

* Fig. 175. a, Globule of human blood, i, Of sheep's blood, c, Of the
blood of a sparrow. These globules are magnified a thousand times in diame-
ter.— p.

t Fig. 176. d, Globule of frog's blood, magnified seven hundred times, and
seen in profile, e, Front view of the same, in which the envelop or coloring
matter is torn, so as to exhibit the central nucleus. — p.

238 THE BLOOD.

the particles were annular in form. Most of the recent mi-
croscopical observers have satisfied themselves of the correct-
ness of Hewson's opinion, that the dark spot in the centre, is
owing to the presence of a solid nucleus in each particle. The
outer vesicle, which encloses the nucleus, is seen torn, (see
fig. 176,) showing the nucleus in one of the red particles of the
frog.

— These vesicles contain the coloring matter of the blood,
and under particular treatment, are rendered soluble, and the
naked nuclei are precipitated in the form of minute granules.
Under any treatment, the latter are found to be insoluble.

Chyle Globules.

— In the blood, Hewson also observed some minute globules,
which he considered those of the chyle. They have since
been observed by Miiller and others. They are abundant in
the chyle, in the lymph, and are probably, as Hewson sug-
gested, identical with the nuclei of the red particles. Accor-
ding to Prevost and Dumas, their diameter is precisely the
same as that of the primitive muscular fibre, the ^^^th part of
an inch. —

The color of the blood has, for a long time, been supposed
to depend upon iron. About the middle of the last century,
Vicentius Menghini published in the Transactions of the Aca-
demy of Sciences of Bologna, an account of experiments which
contributed to establish this sentiment. In this account he
stated that, after washing the coloring matter from the cras-
samentum, he had separated it from the water by boiling ; in
which case it either rose to the surface of the water, or sub-
sided, and left the water clear. After drying with a gentle
heat, some of the coloring matter thus separated, and then
repeatedly washing it, he found that it contained a consider-
able quantity of iron, which was attracted by the magnet.

After exposing a large quantity of the coloring matter to an
intense heat, he found it in a small piece of iron, of a spherical
form, but hollow ; and a powder which was attracted by the
magnet, but appeared more like rust of iron than iron filings.

THE BLOOD. 239

He believes the seat of this iron to be in the coloring matter
of the blood, as neither the serum nor fibrine appeared to con-
tain it. According to his calculation, the blood of a healthy-
man contains more than two ounces of iron.

This doctrine of Menghini has been very generally admitted ;
and by several chemists of the first character, namely, Bucquet,
Fourcroy, Vauquelin, Stc.

240 « THE AORTA.

CHAPTER VIII.

A PARTICULAR ACCOUNT OF THE DISTRIBUTION OF THE AR-
TERIES.

Of the Aorta,* or the Great Trunk of the Arterial System.

When the heart is in its natural position, the right ventricle
is nearly anterior to the left, and therefore, the Aorta, where it
originates from the left ventricle, is behind the pulmonary
artery, and covered by it. Its first direction is so oblique
towards the right side of the body, that it crosses the pulmonary
artery behind, and appears on the right side of it. It has
scarcely assumed this position before its course alters, for it then
proceeds obliquely backwards and to the left ; so as to form a
large curve or arch, which extends to the left of the spine.

The position of this curve or arch is so oblique, with respect
to the body, that the cord or diameter of it, if it were extended
anteriorly and posteriorly, would strike the cartilage of the
third right rib about the middle of its length, and the third
left rib near the head. In consequence of this position of the
curve, the Aorta crosses over the right branch of the
pulmonary artery, and the left branch of the windpipe : and as-
sumes a situation, in front, and to the left of the third dorsal verte-
bra : from this situation it proceeds downwards : in front, but rather
on the left side of the spine, and in contact with that column.f

* This name was given by Aristotle. — h.

f In a case which I recently examined, I found the position of all the
thoracic and abdominal viscera, reversed from side to side. — The right lung had
three lobes and the left two ; the heart was turned to the right side of the tho-
rax, and the venous ventricle and auricle were found on the left side of the organ.
The arch of the aorta was turned from the left to the right side, and the
arteria innominata was sent up on the left side of the neck. — The aorta
pursued its course down on the right side of the spinal column with the vena
cava to its left. The spleen, the cardiac orifice of the stomach, the small lobe
of the liver and the sigmoid flexure of the colon were on the right side ; the
large lobe of the liver and the gall bladder, with the pyloric orifice of the
stomach, and the ccecum were found upon the left. — p.

ri,,i<' I.

//,/./

Il,ll

241

EXPLANATION OF PLATE L
FORE AND BACK VIEWS OF THE HEART.

FIG. I.
A view of the Heart and its Great Vessels, nearly in the Situ-
ation in which it is seen when the Breast is opened.

A. The Superior Vena Cava, returning the blood from the head and arms.

B. The Inferior Cava, tied where it pierces the diaphragm to convey the

blood from the lower parts of the body into the right auricle.
c. The Right Sinus, or Auricle,

D. The Right Ventricle.

E. The Pulmonary Artery ; it is seen to divide ; one branch to pass, under

the arch of the aorta, to the lungs of the right side ; the other to take
an acute turn to those of the left side.

F. The top of the Left Sinus of the Heart, or that which is properly the auricle.

G. The Left Ventricle; it is seen Fig. II. A.
H. The Arch of the Aorta.

I. The Subclavian and Cc/ro/jWof the right side, rising together from the Aorta.
K. The Carotid Artery of the left side.
L. The Subclavian Artery of the left side.
M. A Branch of the Right Coronary Artery.
N. The Left Coronary Vein.

0. A Branch of the Coronary Vein.

FIG. II.

The Posterior Surface of the Heart, and the vessels given off

on the side next the Spine are seen in this view.

A. The Left Ventricle of the Heart.

B. The Trunk of the Pulmonary Artery.

c. The Right Branch of the Pulmonary Artery.

D. The Left Branch of the Pulmonary Artery.

E. The Buds of the Pulmonary Veins of the left side entering the left sinus

of the heart.

F. The Pulmonary Veins of the right side.

G. The Vena sine Pari, or Azygos ; this vein lies upon the spine, collects

the blood from the back part of the thorax, and conveys it to the supe-
rior vena cava.
H. The Superior Vena Cava.

1. The Aorta where it first touches the Spine.
L. The Left Carotid Artery.

M. The Left Subclavian Artery.

N. The Arteria Innominata, or common origin of the subclavian and carotid
of the right side.

VOL. 11. 21

242 THE AOUTA.

The Aorta, as well as the Pulmonary Artery, for a small
distance from the heart, is invested by the pericardium ; and,
when that sac is opened, appears to be contained in it.

After crossing the right branch of the Pulmonary Artery,
a ligament is inserted into it, which proceeds from the main
trunk of the pulmonary artery at its division : this ligament was
the Canalis Arteriosus in the foetus.

As the Aorta proceeds down the spine, it is situated between
the two lamina of the mediastinum, and in contact with the
left lamen, through which it may be seen. It descends between
the crura of the diaphragm, in a vacuity which is sufficiently
large to admit of its passage without pressure from the sur-
rounding parts, and is still in contact with the anterior surface
of the spine, but rather to the left of the middle of it. It con-
tinues this course along the spine until it arrives at the cartilag-
inous substance between the fourth and fifth lumbar vertebrae,
when it divides into two great branches of equal size, which
form an acute angle with each other. These are denominated
the Common or Primitive Iliac arteries.

From the Aorta in this course are sent off the arteries which
are distributed to all the parts of the body for their nourishment
and animation.

From the curve proceed the great branches which supply
the heart, the head, the upper extremities, and part of the tho-
rax. Between the curve and the great primitive iliac arteries,
the Aorta sends off those branches which supply the viscera
contained in the cavities of the thorax and abdomen,* and part
of the trunk of the body. The great Iliac branches of the
Aorta are divided into smaller arteries, which supply the
whole of the lower extremities and some of the viscera of the
pelvis.

Of the Branches which go off from the Arch of the Aorta.

The proper arteries of the heart, denominated Coronary
Arteries, proceed from the Aorta so near to the heart that

* It ought to be observed here, that the viscera, in the lower part of the
pelvis, receive some branches from the internal iliac arteries.

ARTERIA INNOMINATA. CAROTID ARTERIES. 243

their orifices are covered by the semilunar valves, when those
valves are pressed against the sides of the artery. These arte-
ries have been described in the account of the heart, (see page
468, vol. i.)

The arteries of the head and of the upper extremities pro-
ceed from the upper part of the curve in the following man-
ner.

A large trunk, called Arteria Innominata, goes off first.
This is more than sixteen lines in length, when it divides into
two branches, one of which supplies the right side of the head,
and is denominated the Right Carotid : the other proceeds to
the right arm, and from its course under the clavicle, is called,
at first, the Right Subclavian. Almost in contact with the first
trunk, another artery goes off, which proceeds to the left side
of the head, and is called the Left Carotid. Very near to this,
arises the third artery, which proceeds to the left arm, and is
denominated the Left Subclavian. From these great branches
originate the arteries, which are spent upon the head and neck
and the upper extremities.

As these arteries arise from the curve of the Aorta, they are
situated obliquely with respect to each other. The Arteria
Innominata is not only to the right, but it is also anterior to
the two others : and the Left Subclavian is posterior, as well
as to the left of the Left Carotid and the Arteria Innomi-
nata.

244

EXPLANATION OF THE PLATE OF THE AORTIC SYSTEM.

Principal Divisions of the Arteries.

A. Valves of the Aorta. '

B. The Ascending Aorta,
c. The Arteria Innominata.*

Branches of the Arteries.

\l:

D. D. The Subclavian gives off ■<

E. E. The Axillary Artery gives off-

F. F. l^he, Brachial Artery\ "

G. The Radial Artery

H. The Ulnar Artery

I. Interosseous Artery
K. Carotid Artery.

L. External Carotid

The Left Coronary Artery.
The Right Coronary Artery.

The Vertebral Artery.
The Internal Mammary.
The Inferior Thyroid Artery.
The Ascendant Branch of the

Thyroid.
The Transversalis Colli.
The Transversalis Humeri.
The First and Second Intercostals.
The Suprascapularis.

Superior Thoracic Artery.
Thoracica Longior.
Thoracica Humeraria.
Subscapularis.
Circumflexa Posterior.
Circumflexa Anterior.

Profunda Humeri Superior. |
Anastomoticus Major.

Recurrens Radialis Anterior.
Arteria Superficialis Volae.
Arteria Palmaris Profunda.

Recurrens Ulnaris Anterior.
Recurrens Ulnaris Posterior.
Arteria Dorsalis Ulnaris.
Arteria Palmaris Profunda.

Tnterossea Superior Perforans.
Recurrens Interossea.

Arteria Thyroidea Superior.
Arteria Lingualis.
Arteria Labialis vel Facialis.
Arteria Occipitalis.
Posterior Auris.
Arteria Maxillaris Interna.
Arteria Transversalis Faciei.
Arteria Temporalis.

* The Arteria Innominata commonly divides into the Eight Carotid and Sub-
clavian, but here the Left Carotid also is given from it.
t On the left side there is a high bifurcation of this Artery.
X The Lesser Profunda is seen at 16, Plate VI.

245

Principal Divisions of the Arteries.

M. Internal Carotid gives off
N. Vertebral Artery "

o. Basilar Artery "

p. Thoracic Aorta "

* I

Q. Abdominal Aorta "

R. Common Hiacs.

Internal Iliac

T. External Hiacs.

Femoral Artery,
gives off

Popliteal Artery
gives off

Branches of the Arteries.

Arteria Anterior Cerebri.
Arteria Media Cerebri.
Arteria Communicans.

* Arteria Cerebelli Posterior and An-
terior.

Arteria Communicans.
Arteria Cerebri Posterior.

1 to 10. Arteriae Intercosti

1. Arteria Phrenica.
Arteria Cceliaca.
Coronaria Ventriculi.
Arteria Hepatica.
Arteria Splenica.
Mesenterica Superior.

7. Arteriae Capsularis.

8. Arteriae Emulgentes.

9. Arteriae Spermaticae.

10. Mesenterica Inferior.

11. Arteriae Lumbares.
_12. Arteriae Media Sacra.

' 1 . Arteria Obturatoria.

2. Arteria Glutea.

3. Arteria Ischiadica.

4. Arteria Pudica.

Circumflexa Externa.
Circumflexa Interna.
Perforantes.

Arteria Epigastrica.
Circumflexa Ilii.

Profunda Femoris < 2.
(3.

Arteria Articularis Superior Externa.

Interna.

Media.

Inferior Externa.

Interna.

X. Anterior Tibial Artery gives off

Y. Posterior Tibial Artery "
z. Fibular Artery "

Recurrens Tibialis Anticae.
Malleolaris Interna.

Externa.

Arteria Tarsa.

Plantaris Externa.
Interna,

Anterior.
Posterior.

* For the Arteries of ihe Cerebellum, see Plate V. 10, 11, 12.

•}• The Aoria, when it is behind the root of the lungs, gives several arteries to
nourish their substance, called Bronchial Arteries. Lying beside the oesopha-
gus, also, it gives to it a few arteries, the (Esophageal Arteries.

21*

i

246 COMMON CAROTIDS.

The Carotid Arteries.

The two carotid arteries above mentioned have been deno-
minated Common or Primitive Carotids, to distinguish them
from their first ramifications, which are called Internal and
External Carotids,

The Common Carotids

Proceed towards the head on each side of the trachea : at
first they diverge, but they soon become nearly parallel to each
other, and continue so until they have ascended as high as the
upper edge, of the thyroid cartilage, when they divide into the
Internal and External Carotids.

These arteries are at first very near each other, and rather
in front of the trachea ; they gradually diverge and pass back-
wards and outwards on the sides of it, and of the ossophagus,
until they have arrived at the larynx. In the lower part of
the neck they are covered by the sterno-mastoidei, the sterno-
hyoidei, and thyroidei, as well as by the platysma myoidei
muscles. Above, their situation is more superficial ; and they
are immediately under the platysma myoides.

On the inside, they are very near the trachea and larynx,
and the oesophagus ; on the outside, and rather anterior to
them, are the internal jugular veins ; and behind, on each side,
are two important nerves called the symphathetic and the par
vagum. These blood-vessels and nerves are surrounded by
absorbent vessels.

The Common Carotid Arteries send off no branches from
their origin to their bifurcation ; and they appear to preserve
the same diameter throughout their whole extent. In some
few instances the right carotid has been found larger than the
left. The external and internal branches into which they
divide, are neariy equal in the adult ; but it is supposed that
the internal is the largest during infancy. The relative position
of these branches is also different at the commencement from
what it is afterwards. The Internal Carotid forms a curve
which projects outwardly, so as to be exterior to the External
Carotid, while this last proceeds upwards, and rather back-
wards.

EXTERNAL CAROTID.

247

The External Carotid Artery

May be considered as extending from its commencement,
Fig. 177.* whicii is on a line with

the superior margin of
the thyroid cartilage, to
the neck of the condyle
of the lower jaw, or near
it.

At first it is superfi-
cial ; but as it proceeds
upwards it becomes deep-
seated: and passing un-
der the digastric andstylo-
hyoidei muscles, and the
ninth pair of nerves, is
covered by the Parotid
Gland. After this, it
again becomes superfi-
cial ; for, the temporal ar-
tery which may be regard-
ed as the continuation of
the external carotid, passes over the zygomatic process of the
temporal bone.

As the External Carotid supplies with blood the upper
part of the neck and throat, the exterior of the head and face,
and the inside of the mouth and nose ; its branches must
necessarily be numerous, and must pass in very various direc-
tions.

Thus, soon after its commencement, it sends off, in an ante-
rior direction, three large branches ; viz. to the upper part of

* The carotid arteries with the branches of the external carotid. 1. The
common carotid. 2. The external carotid. 3. The internal carotid. 4. The
carotid foramen in the petrous portion of the temporal bone. 5. The superior
thyroid artery. 6. The lingual artery. 7. The facial artery. 8. The mastoid
artery. 9. The occipital. 10. The posterior auricular. 11. The transverse
facial artery. 12. The internal maxillary. 13. The temporal. 14. The as-
cending pharyngeal artery.

248 SUPERIOR THYROID. LINGUAL.

the neck, to the parts within the lower jaw, and to the cheeks
and lips. These are denominated, the .Swpenor Thyroid, the .
Sublingual, and the Facial. It then sends off to the back
of the head one which is called the Occipital; and, as it pro-
ceeds upwards near the condyle of the lower jaw, another which
passes internally, behind the jaw, to the deep-seated parts in
that direction. After this, it forms the temporal artery, which
supplies the forehead and central parts of the cranium. Besides
these larger branches, the external carotid sends off two which
are smaller ; one from near the origin of the sublingual artery,
which is spent principally upon the pharynx and fauces, and
is called the Inferior Pharyngeal : and another, while it is
involved with the parotid gland, which goes to the ear ; and
is therefore called Posterior Auris.

These arteries are distributed in the following manner :

1. The Superior Thyroid Branch

Comes off very near the root of the external carotid, and
sometimes from the common trunk ; it runs obliquely down-
wards and forwards, in a meandering course, to the thyroid
gland, where it is spent. During this course it sends off one
branch to the parts contiguous to the os hyoides ; another to
the neighborhood of the larynx : and a third branch which
may be termed laryngeal, that passes with a small nerve
derived from the laryngeal branch of the par vagum, either
between the os hyoides and thyroid cartilage, or the thyroid
and cricoid cartilages, to the interior muscles of the larynx ;
and finally returns again to terminate externally.

While in the thyroid gland this artery anastomoses with the
inferior thyroid, and also with its fellow on the opposite side.

2. The Lingual, or Sublingual Branch

Goes off above the last mentioned artery, and very near it ;
but in a very different direction, for it runs upwards and for-
wards, to the tongue. In this course it crosses obliquely the

^

FACIAL ARTERY. 249

OS hyoides, and is commonly within the hyoglossus muscle.
It gives off branches to the middle constrictors of the pharynx,
and to the muscles contiguous to the tongue. It also sends off
a branch which penetrates to the back of the tongue, which is
called, from its situation, Dorsalis Lingua. At the anterior
margin of the hyoglossus muscle it divides into two branches,
one of which passes to the sublingual gland and the adjacent
parts, and is thence called Sublingual; while the other branch,
the Ranina, passes by the side of the genio-glossus muscle to
the apex of the tongue.

3. The Facial or External Maxillary

Runs obliquely upwards and forwards under the ninth pair
of nerves the stylo-hyoideus muscle and the tendon of the
digastric, across the lower jaw and cheek, towards the inner
corner of the eye, in a serpentine course. Before it crosses the
jaw it sends off several branches, viz. to the pharynx, the ton-
sils, the inferior maxillary gland and the parts contiguous to it.
It also sends a branch towards the chin, which passes be-
tween the mylo-hyoideus, the anterior belly of the digastric,
and the margin of the lower jaw : and some of its branches
continue to the muscles of the under lip. This branch is called
the Submental.

This artery then passes round the basis or inferior edge of
the lower jaw, very near the anterior margin of the masseter
muscle, and is so superficial that its pulsations can be readily
perceived. After this turn, its course is obliquely upwards and
forwards. Near the basis of the jaw it sends off a branch to
the masseter, which anastomoses with small branches from the
temporal ; and another which passes superficially to the under
lip and contiguous parts of the cheeks. This last is called the
Inferior Labial.

After the artery has passed as high as the teeth in the lower
jaw, it divides into two branches; which go, one to the under,
and the other to the upper lip ; that to the upper lip is largest.
These branches are called Coronary.

The Coronary Artery of the lower lip passes under the

250 INFERIOR PHARYNGEAL. OCCIPITAL.

muscles called Depressor Anguli Oris, and Orbicularis Oris,
into the substance of the lip, and anastomoses with its fellow of
the opposite side.

The Coronary Artery of the upper lip passes under the
zygomaticus major and the orbicularis, and very near the mar-
gin of the upper lip internally. It also anastomoses freely with
its fellow on the opposite side. These anastomoses are fre-
quently so considerable that the arteries on one side can be well
filled by injecting those of the other. The coronary branches,
as well as the main trunk of the facial artery, observe a serpen-
tine or tortuous course ; in consequence of which they admit of
the motions of the cheeks and lips, which they would greatly
impede, if they were straight.

From the upper coronary artery a branch continues in the
direction of the main trunk of the facial artery, by the side of
the nose, which extends upwards, sending off small branches in
its course, and finally terminates about the internal angle of the
eye and the forehead, where it has received the name of the an-
gular artery.

4. The Inferior Pharyngeal

Is a very small artery ; it rises posteriorly from the external
carotid, opposite to the origin of the sublingual, and passes
upwards to the basis of the cranium. In this course it sends
several branches to the pharynx, and to the deep-seated parts
immediately contiguous.

It also sends branches to the first ganglion of the sympathetic
nerve, to the par vagum, and to the lymphatic glands of the
neck ; and, finally, it enters the cavity of the cranium by the
posterior foramen lacerum.

In some cases it also sends a small branch through the anterior
foramen lacerum.

5. The Occipital Artery

Arises from the posterior side of the external carotid, nearly
opposite to the facial, but sometimes higher up ; it ascends
obliquely, and passes to the back part of the cranium, between

POSTERIOR AURIS OR STYLO-MASTOID ARTERY. 251

the transverse process of the atlas and the mastoid process of
the temporal bone.

In this course it passes over the internal jugular vein and the
eighth pair of nerves, and under the posterior part of the
digastric muscle: it lies very near to the base of the mastoid
process, and under the muscles luhich are inserted into it.
After emerging from these muscles, it runs superficially upon
the occiput, dividing into branches which extend to those of
the temporal artery.

The Occipital Artery sends off branches to the muscles
which are contiguous to it, and to the glands of the neck.

It also Drives off the following branches ; one called the Men-
ingeal, which passes through the posterior foramen lacerum
to the under and back part of the dura mater : one to the
exterior parts of the ear: another which passes downwards,
and is spent upon the complexus, trachelo-mastoideus, and
other muscles of the neck : and several smaller arteries.

The artery next to be described, is sometimes sent off by the
occipital artery.

6. The Posterior Auricular, or Stylo- Mastoid Artery,

When it arises from the external carotid, comes off poste-
riorly from the artery, where it is involved with the parotid
gland, and passes backwards between the meatus auditorius
externus and the mastoid process. It then ascends, in a curved
direction, and terminates behind the ear.

In this course it sends off small branches to the parotid gland,
and to the digastric and sterno-mastoid muscles. Sometimes a
distinct branch, which is particularly visible in children, passes
through an aperture in the meatus auditorius externus, and is
spent on its internal surface.

It also sends off a branch which enters into the Stylo-Mas-
toid Foramen, constituting the proper stylo-mastoid artery ; it
supplies small vessels to the membrana tympani and the lining
membrane of the cavity of the tympanum ; to the mastoid cells ;
to the muscle of the stapes, and to the external semicircular canal.
One of these vessels anastomoses in the upper and posterior part

252 THE TEMPORAL ARTERY.

of the cavity of the tympanum, with a small twig derived from
the artery of the dura mater. When it has arrived behind the
ear, the Posterior Auricular Artery terminates upon the exter-
nal ear and the parts contiguous to it.

Distribution of the Branches of the External Carotid Artery,
after Sir Charles Bell. (See Plate III., facing page 252.)

A. The Common Carotid Artery.

B. The Internal Carotid Artery, or Artery of the Cerebrum,
c. The External Carotid Artery.

D. The Lower Thyroid Artery, being a branch of the Subclavian Artery.

E. The Upper Thyroid Artery, being the first branch of the Carotid.

Branches of the External Carotid Artery.

1 . The Lingual Artery.

2. The Facial Artery, or Labial Artery.

3. The Submental Artery. »

4. The Upper and Lower Coronary Arteries.

5. The Inosculations of the extreme Branches of the Facial Artery, with
the Ophthalmic Artery.

6. The Occipital Artery.

7. The place where it frequently sends down inosculations to the verte-
bral artery.

8. The Lesser Posterior Artery of the Ear.

9. A Branch sometimes called Posterior Temporal Artery.

10. Posterior Artery of the Ear, or Stylo-mastoid.

11. The continued Branch of the External Carotid, sometimes called the
Temporal Artery ; it divides into the submaxillary and proper temporal
artery.

12. The Internal Maxillary Artery. See the distribution of this artery in
the next Plate, Fig. I. 14, and Fig. II.

13. The Transverse Artery of the Face.

14. The Temporal Artery, dividing into anterior and posterior temporal arte-
ries. There are other branches less superficial. The deep Temporal is
a branch of the Internal Maxillary.

7. The Temporal Artery

Is considered as the continuation of the external carotid,
because it preserves the direction of the main trunk ; although
the internal maxillary is larger.

After parting with the internal maxillary it projects out-

/'////, ///

THE TEMPORAL ARTRY. 253

wards ; and passing between the nrieatus audltorus externus
and the condyle of the lower jaw, continues upwards, behind
the root of the zygomatic process of the temporal bone, to the
aponeurosis of the temporal muscle : on the outside of which,
immediately under the integuments, it divides into two large
branches denominated anterior and posterior.

Before this division the temporal artery sends off several
branches of very different sizes.

One, which is considerable in size, and called the Transverse
Facial Branch, advances forwards across the neck of the condyle
of the lower jaw, and through the substance of the parotid
gland, and giving small branches to the masseter, runs parallel
to the parotid duct, and below it. This branch is spent upon
the muscles of the face, and- anastomoses with the other vessels
of that part, the infra-orbital and facial arteries.

The temporal gives off small branches tt) the parotid gland
and to the articulation of the jaw. From the last mentioned
branch small twigs pass to the ear, one of which enters the
cavity of the tympanum by the glenoid fissure.

While this artery is on a line with the zygoma, it sends off a
branch called the middle temporal artery, which penetrates the
aponeurosis of the temporal muscle, and ramifies under it upon
the muscle, in an anterior direction.

The two great branches of the temporal artery are dis-
tributed in the following manner. The Anterior passes up in
a serpentine direction on the anterior part of the temple, and
supplies the front side of the head and the upper part of the
forehead.

The Posterior extends upwards and backwards, and supplies
the scalp on the lateral and middle part of the cranium, and also
the bone.

Ramifications from each of these branches anastomose on
the upper part of the cranium with those of its fellow of the
opposite side. The anterior branch also anastomoses on
the forehead with the facial and ophthalmic arteries ; and the
posterior branch with the occiphal artery on the back part of
the head.

VOL. II. 22

254 INTERNAL MAXILLARY ARTERY.

8. The Internal Maxillary Artery*

Arises from the external carotid under the parotid gland, at
a little distance below the neck of the condyloid process of the
lower jaw, and extends to the bottom of the zygomatic fossa
varying its direction in its course. It is rather larger than the
temporal.

— On leaving the external carotid, it first runs downwards and
inwards, so as to get under cover of the ramus of the jaw, then
inwards between the two pterygoid muscles, then upwards between
the two heads of the external pterygoid muscle till it reaches the
spheno-maxillary fossa, where it makes its last turn forwards
and inwards becoming horizontal. —

— 1. Branches given off from the Artery near the Ramus of

the Jaw. —

A. It first sends off one or two small branches to the ear, and
a twig called tympanic which penetrates into the cavity of the
tympanum by the glenoid fissure.

B. It also sends off a small artery called the Lesser Meningeal,
(meningea parva) which passes upwards, and after giving
branches to the external pterygoid and the muscles of the pal-
ate, passes through the foramen ovale, and is spent upon the
dura mater about the sella turcica.

c. It then sends off one of its largest branches, the Great or
middle Artery of the Dura Mater, (meningea magna) which
passes in a straight direction to the foramen spinale, by which
it enters into the cavity of the cranium.

This artery ramifies largely on the dura mater, and makes
those arborescent impressions which are so visible in the
parietal bone. It generally divides into two great branches :

* The general situation of this artery, and the distribution of several of its
most important branches, cannot be understood without a knowledge of the
bones through which ihey must pass. The student of surgery will therefore
derive benefit from a re-examination of these bones, and of the zygomatic
fossa, (fee, when he studies this artery. (See vol. i. page 122.) He ought to
be well acquainted with this subject, if he should undertake the management
of necrosis of the jaw bones ; or of those fungous tumours, which sometimes
originate in the antrum maxillare : as well as of several other diseases of
these parts.

INTERNAL MAXILLARY ARTERY. 255

the anterior which is the largest, passes over the anterior
and inferior angle of the parietal bone : the posterior branch
soon divides into many ramifications, which are extended late-
rally and posteriorly.

It furnishes the twig which passes to the ear by the hiatus
of Fallopius, and anastomoses with the small branches of the
stylo-mastoid artery.

It also supplies some other small vessels which pass to the
cavity of the tympanum by small foramina near the junction of
the squamous and petrous portions of the temporal bone.

D. The next branch sent off by the internal maxillary leaves
it about an inch from its origin, and is called the Inferior Max-
illary or Dental. It passes between the internal pterygoid
muscle and the bone, and after giving small branches to the
contiguous muscles, enters the canal in the lower jaw, in com-
pany with the nerve. This canal has a very free communi-
cation with the cellular structure of the jaw, and the artery in
its progress along it sends branches to the respective teeth and
the bone. At the anterior maxillary foramen this artery sends
off a considerable branch which passes out and anastomoses
with the vessels on the chin, while another branch passes for-
ward and supplies the canine and incisor teeth and the bone
contiguous to them.

Sometimes the inferior maxillary artery divides into two
branches before it has arrived at this foramen. In this case,
one of the arteries passes out of the foramen, while the other
continues to the symphysis.

— 2. Branches given off by the Artery between the Pterygoid

Muscles. —

E. Two branches (temporales profundi) pass off to the
temporal muscle, which originate at a small distance from each
other; one of them passes upwards on the tendon of the tem-
poral muscle ; the other arises near the tuberosity of the upper
maxillary bone : they are called the exterior deep, and the
interior deep temporal artery. They are both spent upon the

256

INTERNAL MAXILLARY ARTERY.

temporal muscle ; but the interior branch sends a small twig
into the orbit of the eye.

F. There are some small branches which pass to the Ptery-
goid Muscles and to the Masseter, which arise either from
the internal maxillary artery, or from the interior deep tempo-
ral. They are generally small, and often irregular.

— 3. Branches given off opposite the Ptery go-maxillary

Fissure. —

G. An artery, particularly appropriated to the cheek, called
buccal or buccinator, perforates the buccinator muscle from
within outwards, and generally terminates on the buccinator,
the zygomaticus major, and the muscles of the lips. This Ar-
tery of the Cheek is very irregular in its origin, sometimes
arising from the internal maxillary, sometimes from the deep
temporal, and sometimes from the suborbitary, or from the
alveolar artery, to be immediately described.

H. The Alveolar Artery or the Artery of the Upper Jaw
(superior dental) arises generally from the internal maxillary,
but sometimes from one of its branches. It winds round the
tuberosity of the upper jaw, and sends branches to the bucci-
nator muscle, to the bone and the gums, to the antrum High-
morianum, and some of the molar teeth : and also to the teeth
generally, by means of canals somewhat analogous to that of
the lower jaw.

I. The Infra orbital Artery arises from the internal maxil-
lary in the zygomatic fossa, and soon enters the infra orbital
canal, through which it passes to the face, and emerges below
the orbit of the eye, supplying the muscles in the vicinity, and
anastomosing with the small ramifications of the two last
described arteries, and those of the facial artery and the
ophthalmic.

This artery in its course sends off small twigs to the perios-
teum, the adipose membrane, and the muscles in the inferior
part of the orbit, and also to the great maxillary sinus or antrum
Highmorianum, and to the canine and incisor teeth.

//,'/- //■

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r-

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If

INTERNAL MAXILLARY ARTERY. 257

— -4. Branches given off from the Internal Maxillary Artery
in the Spheno-maxillary-fossa. —

J. The Palato-Maxillary or Superior Palatine Artery,
arises in the spheno-maxillary fossa, and, descending behind
the upper maxillary bone, enters the posterior palatine canal,
through which it passes to the roof of the mouth. It generally
forms two branches, the largest of which advances forward,
supplying the palate and gums, and finally sends a twig
through the foramen incisivum to the nose, while the posterior
branch, which is much smaller, supplies the velum pendulum
palati.

K. The Ptery go-Palatine or Superior Pharyngeal, is a
small vessel, which sometimes arises from the artery next to
be mentioned. It is spent upon the upper part of the pharynx,
and a branch passes through the pterygo-palatine foramen,
which is spent upon the arch of the palate and the contiguous
parts.

L. The Internal Maxillary at length terminates in the
Spheno-Palatine, or Lateral Nasal Artery, which passes
through the spheno-palatine foramen to the back part of the
nose. This artery sometimes separates into two branches
before it enters the foramen ; sometimes it enters singly, and
divides into two branches soon after ; one of them is spread
upon the septum, and the other upon the external side of the
nose; each of these branches ramifies very minutely upon the
Schneiderian membrane and its processes in the different
sinuses, and also in the ethmoidal cells.

Distribution of the Internal Carotid, the Vertebral and In-
ternal Maxillary Arteries, as seen upon making a vertical
Section of the Head, (see Plate W . facing page 257.)

A. The Upper Jaw Bone ; part of it is torn away.

B. The Lower Jaw Bone ; all the angle of the right side is taken away, to

show the internal maxillary artery.
c. The tongue.

D. The Antrum Highmorianum, torn open.
22*

258 INTERNAL MAXILLARY ARTERY.

E. The Vertebra; of the Neck, cut to show the passage of the artery,

encased in the bones.

F. F. The Skull-cap, sawn through exactly in the length of the longitudi-

nal sinus.

G. The Falx, which divides the hemispheres of the Brain.
H. The longitudinal Sinus.

I. The Fourth Sinus, returning the blood from the lower sinus of the falx,

and from the vena galeni.
K. Right Lateral Sinus.
L. The Tentorium, which covers the cerebellum, and supports the posterior

lobes of the cerebrum.

Arteries.

1. The Common Carotid Artery.

2. The Internal Carotid Artery.*

3. The External Carotid Artery.

4. The Vertebral Artery ; the processes of the vertebrae being cut away.

5. The last and violent turn of the Vertebral Artery, before entering the
foramen magnum of the occipital bone.

6. The violent contortions of the Internal Carotid Artery, before entering
the skull.

7. The point of the Internal Carotid Artery, where, after making its turns
in its passage through the bone, it appears by the side of the sella tur-
cica. See Plate at page 252.

8. The Ophthalmic Artery, derived from the carotid. It is this artery

which is seen to inosculate with the Facial Artery, in the preceding
Plate, at page 252.

9. The Thyroid Artery.
10. The Lingual Artery.

II. The Facial Artery, cut short ; it is seen in the Plate, at page 252, Fig.
2, passing over the jaw.

12. The continued Trunk of the External Carotid Artery ; it is about to
divide into the temporal and internal maxillary arteries. See the pre-
ceding Plate (11.)

13. The Temporal Artery, cut short.

14. Internal Maxillary Artery.

15. That Branch of the Internal Maxillary Artery, which passes into the

lower jaw.

* Internal Carotid. In Dr. Hooper's collection of preparations, there is a
curious example of the ulceration of this artery. A man intending to destroy
himself, attempted to swallow pins tied together; they stuck in the pharj'nx,
and in time penetrated to this artery, which suddenly cut him off.

INTERNAL CAROTID ARTERY. 259

16. The Great or Middle Artery oi the Dura Mater; a branch of the
internal maxillary.*

17. The Artery of the Upper Jaw.

18. The Infra Orbital Artery ; it is seen to pass out upon the face.

Fig. 2, is a Plan of the Internal Maxillary Artery.

1. The Meningeal Artery, or great middle artery of the dura mater. f

2. The Inferior Maxillary Artery. %

3. Irregular Arteries : the Pterygoid Arteries.

5. The Deep Internal Temporal Artery.

6. The Artery of the Cheek.

7. The Artery of the Upper Jaw.

8. The hifra Orbital Artery.

9. The Superior Palatine Artery.

10. The Origin of the Superior or Upper Pharyngeal Artery.

The Internal Carotid Artery

Is sometimes called the Artery of the Brain, as it is almost
entirely appropriated to that viscus.

From its origin to the commencement of its ramifications, the
course of this blood-vessel is peculiarly tortuous. In conse-
quence of which, the force of the blood in it is greatly dimin-
ished before it arrives at the brain.

An instance of this curvature occurs immediately after
its separation from the external carotid, when it protrudes out-
wards so much as to be exterior to that vessel ; after this it
ascends to the carotid canal, and in its course is in contact, or
very near the par vagum and sympathetic nerves.

* It is this artery which rises through the spinous hole in the sphenoid bone,
and then runs on the lower angle or spinous process of the parietal bone : here
it generally lies in a deep channel, and gives occasion to a kind of rule in sur-
gery, to avoid applying the trephine at this part.

f This artery enters the skull by the foramen spinale of the sphenoid bone,
and is the same that makes the deep furrow in the inside of the parietal bone.
Mr. Walker, of Edinburgh, communicated a case where an arrow shot into the
skull wounded this artery.

I Lower Maxillary. This artery enters at the posterior foramen of the lower
jaw-bone, and courses within the bone, and appears on the chin, coming out
through the mental foramen. In pulling the last molaris of the lower jaw, if
the inner plate of the bone be broken off, and this artery torn up among the
cells of the bone, the patient may die of bleeding.

260 INTERNAL CAROTID ARTERY.

The carotid canal in the petrous portion of the temporal bone
is by no means straight ; it forms a semicircular curve, forwards
and inwards; and its upper portion, which is nearly horizontal,
opens obliquely against the body of the sphenoid bone, at a
small distance from it. Therefore, after the artery has passed
through the canal, it must turn upwards to get fairly into the
cavity of the cranium ; and, of course, its direction while in the
canal, forms almost a right angle with its direction before it
enters, and after it emerges from it.

In consequence of this curvature, much of the momentum of
the blood must be impressed upon the walls of the cranium, and
is thus taken off from the brain, so as not to disturb the action
of its delicate structure.

After the artery has arrived at the end of the carotid canal,
and has turned upwards to get within the cavity of the cranium,
it bends forwards, and passes nearly in a horizontal direction,
through the cavernous sinus on the side of the sella turcica, to
the anterior clinoid process ; here it again forms a considerable
curve, which is directly upwards, and then it perforates the
dura mater.

These curvatures must also deprive the blood of the carotid of
a portion of the momentum which it has retained after leaving
the bone.

The object of these various flexures of the internal carotid
appears to be analogous to that of the Rete Mirabile in certain
quadrupeds, which is formed by the division of this artery
into many small branches, that reunite again, without pro-
ducing any other effect than the diminution of the momentum
of the blood.

During its course from the place of bifurcation to its entrance
into the carotid canal, the internal carotid artery very rarely
sends off any branches. In the canal it gives off a small twig
which enters the cavity of the tympanum ; and sometimes a
second, which unites with the Pterygoid branch of the internal
maxillary.

As it goes by the sella turcica, it passes through the
cavernous sinuses, and gives off two branches, which are

OPHTHALMIC ARTERY. 261

called the Posterior and Anterior Arteries of the Cavernous
Sinus or Receptacle.

The posterior branch goes to that part of the dura mater
which is connected with the posterior clinoid process, and the
cuneiform process of the occipital bone. It likewise gives
branches to several of the nerves which are contiguous, and to
the pituitary gland.

The anterior artery also gives branches to the contiguous
nerves, to the dura mater, and the pituitary gland.

When the internal carotid turns upwards at the anterior clinoid
process, it sends off the

Ophthalmic Artery,

Which passes under the optic nerve through the foramen
opticum into the orbit of the eye, and is about a line and a half
in diameter.

Although this artery enters the orbit under the optic nerve,
it soon takes a position on the outside of it, but afterwards
gradually proceeds to the innner side of the orbit, crossing over
this nerve in an oblique direction, and finally passes out of the
orbit near the internal angle. In this spiral course it sends off
numerous branches, viz.

A. To those parts which are auxilliary to the eye.

B. To the ball of the eye.

0. To the cavity of the nose, through small foramina in the
ethmoid bone, and

D. To the forehead and external side of the nose.
These branches generally go off in the following order :

1. The Lachrymal Artery arises soon after the ophthalmic
arrives within the orbit, and passes above the abductor muscle
to the lachrymal gland, where it terminates, sending off many
small branches in its course.

2. The Central Artery of the retina also leaves the ophthal-
mic soon after its arrival in the orbit : it is a small vessel which
penetrates into the centre of the optic nerve, and, passing with
it into the eye, is spread upon the internal surface of the retina.
Here it appears to terminate in the adult ; but in the foetus it

262 OPHTHALMIC ARTERY.

is continued through the vitreous humor to the capsule of the
crystalHne lens.

3. While the ophthalmic is passing over the optic nerve the
branches which enter the ball of the eye leave it. Their number
varies, but they form three classes, viz. The Long Ciliary, the
Short Ciliary, and the Anterior Ciliary arteries, (see descrip-
tion of the eye,) the supra orbitary and muscular branches leave
it also near the same place.

4. The Supra Orbital Branch often gives off several mus-
cular twigs: but it passes out of the orbit through the supra
orbitar foramen, and generally divides into two branches, one of
which is spent upon the periosteum, and the other upon the skin
and muscles of the forehead.

5. There are sometimes two muscular branches, a Superior
and an Inferior. The superior branch is often deficient :
when it exists it supplies the levator palpebrae, the levator
oculi, obliquus superior, &c. ; but these parts are often sup-
plied by the branches above mentioned. The supra orbitar so
frequently gives off branches to the muscles, that it has been
called the Superior Muscular Branch. The inferior muscular
branch is more constant. It commonly supplies the rectus
inferior, the abductor, and the inferior oblique muscles, and also
the lachrymal sac, and the lower eyelid, Sic.

When the artery is on the inside of the nerve it sends off the
two branches to the cavity of the nose, viz. The Ethmoidal
Arteries ; and, also, branches to the eyelids.

6. The Posterior Ethmoidal branch is first. It passes
between the- levator and abductor muscles, and above the
obliquus seperior, and penetrates the cavity of the cranium by
the posterior orbitary foramen : after giving some twigs to the
dura mater, it passes to the posterior cells of the ethmoid by
the foramina of the cribriform plate of that bone, and sends a
small branch to the Schneiderian membrane on the back part of
the septum of the nose.

7. The Anterior Ethmoidal artery arises from the ophthal-
mic nearly opposite to the anterior orbitary foramen, through
which it passes : and after entering the .cranium is distributed

BRANCHES OF THE INTERNAL CAROTID TO THE BRAIN. 263

like the other through some of the foramina of the cribriform
plate to the anterior ceils of the ethmoid bone, and to the ante-
rior part of the Schneiderian membrane on the septum of the
nose, to which it sends a considerable branch.

In its course it sends twigs to the frontal sinuses, and to the
dura mater and its falciform process.

8. The arteries of the Paljpebrce are called Superior and In-
ferior ; they leave the ophthalmic near the loop or pulley of the
superior oblique muscle. The inferior comes off first ; it sends
branches to the ligaments of the tarsus, the caruncula lachry-
malis, and the parts connected with the cartilage of the under
eyelid, and unites with the lachrymal artery near the external
canthus, forming an arch called the Inferior Tarsal Arch.

9. The Superior Artery supplies the superior part of the
orbicularis muscle, the ligament and caruncula also : and it
likewise unites with a twig of the lachrymal, and forms the
superior tarsal arch.

Soon after sending off the palpebral branches, the Ophthalmic
Artery arrives at the internal canthus, and then finally divides
into two branches, the nasal and the frontal.

10. The Nasal Branch passes above the superior part of the
lachrymal sac, and the ligament of the eyelid to the nose ; after
sending a twig to the frontal muscle and the lachrymal sac, it
passes down the side of the nose and anastomoses with the
facial artery.

11. The Frontal Artery is not so large as the nasal ; it gene-
rally divides into three parts. A superciliary branch, which is
principally spent upon the eyebrows ; a superficial branch, which
is spent upon the forehead; and a branch which is distributed
to the pericranium.

The Internal Carotid, soon after parting with the ophthalmic,
sends off, in a posterior direction, a branch to join one from the
vertebral artery. From its destination, this vessel is called the
arteria communicans.

After this it sends off another branch, which is so large that
it may be considered as a continuation of the main trunk : this
is called the middle artery of the brain, or the Arteria Sylvi-

264 RIGHT AND LEFT SUBCLAVIAN ARTERIES.

ana. It runs outwards nearly in the direction of the fossa Sylvil,
which separates the anterior from the middle lobes of the cere-
brum. In its course it divides and subdivides into numerous
branches, which are spread upon the Pia Mater, and finally
enter the surface of the brain in a very minute state.

The internal carotid then terminates in a branch, which is
smaller than the last mentioned, and from its situation is called
the Anterior Artery of the Brain, or Arteria Callosa. This
vessel first inclines towards its fellow on the opposite side, and
after approaching within half an inch of it, forms another curve,
and runs forward to the anterior part of the brain, dividing
itself gradually into two branches, which pass in several
directions.

Where these anterior arteries are nearest to each other, a small
transverse branch, which passes at right angles, connects them
together. This branch is called communicans anterior, and com-
pletes the anterior part of the Circle of Willis.

It crosses immediately before the sella turcica and pituitary
gland, and sends off branches which pass to the third ventricle,
to the fornix and septum lucidum, and also to the pia mater.

The Anterior Arteries of the brain also send off branches to
the optic and olfactory nerves ; to the opposite surfaces of the
two hemispheres on each side of the falx, to their inferior sur-
faces, and to the corpus callosum.

They have likewise some branches which anastomose with
those of the middle artery of the brain, and of the vertebral
artery.

The Subclavian Arteries.

The Right Subclavian may be considered as the continuation
of the arteria innominata. This last mentioned artery, after
leaving the aorta, forms a curve or arch, which extends obliquely
backwards and outwards, over the first rib to the axilla, crossing
the trachea in its course. At the distance of an inch and a
quarter or an inch and a half from its origin, it sends off the
right carotid, and then, assuming the name of Right Subclavian,
continues in the above stated direction.

INTERNAL MAMMARY ARTERY. 265

The chord of the curve of this artery, and the chord of the
curve of the aorta, are not in the same direction, but form an
angle with each other.

The position of the Left Subclavian is somewhat different
from that of the right. Its origin is posterior, and, therefore, the
direction of the chord of its curve is more immediately lateral.
The curve or arch is also smaller. The situation of the two
subclavians as relative to the contiguous parts, is, therefore,
somewhat different ; but each of them proceeds between the
anterior and the middle scaleni muscles, and when they have
arrived at these muscles, their respective positions are very similar.

The anterior and middle scaleni muscles arise from the trans-
verse processes of several of the cervical vertebrae, and are
inserted into the first rib, one before the other, so as to leave a
considerable space between them. The subclavian arteries
pass through this space, but before they arrive at it, and when
they are very near the above mentioned muscles, they send off
several very important branches in various directions, viz. to the
cavity of the cranium, to the parietes of the thorax, to the
thyroid gland, and to the lower part of the neck.

They proceed near to the scaleni muscles before they send off
any branches ; and it is to be observed, that the subclavian veins
which correspond with these arteries, are anterior to them, for
they pass before the scaleni muscles, and not between them.
— It is common, for greater clearness in description to divide the
course of the subclavian artery into three portions. 1st. That
between its place of origin and the anterior scalenus muscle,
from which its main branches are sent off; 2. That immediately
behind the scalenus ; 3. That between the outer edge of the
scalenus and the lower border of the first rib, where the sub-
clavian takes the name of axillary. —

The Internal Mammary Artery

Goes downwards, from the lower and anterior part of the
subclavian, along the inner side of the anterior scalenus muscle.
It proceeds, exterior to the pleura, across the cartilages of the
true ribs, and near the middle ; and, continuing between the
cartilages and the diaphragm, exterior to the peritoneum,
VOL. II. 23

266 THYROID AND VERTEBRAL ARTERIES.

terminates on the rectus abdominis muscle, in branches which
anastomose with those of the epigastric artery. In this course,
it gives branches to ahnost all the parts to which it is contig-
uous, viz. to the muscles and glands at the lower part of the
neck ; to the thymus gland ; to the parts in the intercostal
spaces ; to the sternum ; to the mediastinum and pericardium ;
to the diaphragm and to the muscles of the abdomen.

From some of its ramifications upon the parts between the
ribs, small branches go off to the mamma, and thereby give a
name to the artery. There is also a small vessel which is sent
off by the mammary artery, or by one of its upper branches
which accompanies the phrenic nerve to the diaphragm.

The Inferior Thyroid Artery

Arises from the upper side of the subclavian nearly opposite
to the origin of the internal mammary. It passes upwards and
inwards, between the carotid artery and the spine, to the thy-
roid gland : and then it anastomoses with the branches of the
superior thyroid on the same side, and with those of its fellow
on the opposite side.

This vessel sometimes sends off large branches to the muscles
at the lower part of the neck. — One called the ascending cervi-
cal, usually arises from it and runs upwards between the edges
of the scalenus anticus and rectus anticus major, ramifying on
these muscles and anastomosing with branches sent from the
vertebral artery. —

The Vertebral Artery

Arises from the upper and posterior part of the subclavian.
It goes upwards and backwards between the muscles which
lie on the front of the spine, and passing under the transverse
process of the sixth or seventh cervical vertebra, enters into
the canal formed in the transverse processes of the vertebrae.
In this course, as it proceeds from the third to the second cer-
vical vertebra, it inclines outwards laterally, and, in its passage
from the transverse process of the second to that of the first
vertebra, it forms a considerable curve, the convexity of which

THE BASILAR ARTERY. 267

has a lateral and external aspect. After passing the transverse
process of the Atlas, it is turned suddenly backwards, in a
groove, and finally passes through the great occipital foramen
into the cavity of the cranium. It then proceeds upon the
cuneiform process of the occipital bone, under the Medulla
Oblongata, and joins its fellow so as to form an acute angle
with it near the union of the medulla oblongata with the pons
Varolii. From each of the vertebral arteries before their
union, there generally goes off a small branch called the Pos-
terior Meningeal, which is spent upon the posterior part of the
dura mater.

The trunk formed by the union of the vertebral arteries is
called

The Basilar Artery.

It extends forward near to the anterior part of the pons
Varolii, where it bifurcates ; but previously sends off several
branches on each side. The first pair go off in a lateral
direction, soon after its commencement, near the back part of
the' pons Varolii, and are spent upon the medulla oblongata,
the pons Varolii, and the other contiguous parts, and also upon
the fourth ventricle and the Plexus Choroides of that cavity.
They are called the Posterior or Inferior Arteries of the Cere-
helium.

Two other lateral branches, which are called the Superior
Arteries of the Cerebellum, go off from the Basilar artery,
near its anterior extremity. These are principally spent upon
the crura of the cerebellum and cerebrum : upon the cerebel-
lum itself, and the contiguous parts.

Soon after sending off the last mentioned arteries, the Basi-
lar artery divides into two branches, which also take a lateral
■direction, and are of considerable size. In their course out-
ward, these branches are curved with their convexity forward.
About ten or twelve lines from its commencement, each of
them sends off a branch called the Arteria Communicans,
which passes directly forward, and communicates with the
internal carotid, thus forming the arrangement which is called

268 ARTERIES OF THE BRAIN.

the Circle of Willis.^ After sending off these arteries, they
continue their lateral direction, and are distributed principally
to the posterior parts of the cerebrum. These terminating
branches of the Basilar Artery, are called the Posterior Ar-
teries of the Cerebrum.

Arteries of the Brain, which are derived from the Internal
Carotid and Vertebral, (see Plate V. facing page, 268.)

A. A. The Anterior Lobes of the Cerebrum.

B. B. The Middle Lobes of the Cerebrum.

c. c. The Posterior Lobes of the Cerebrum, which rest upon the tentorium.

D. The Ri^ht and Left Lobes of the Cerebellum.

E. The Medulla Oblongata.

F. The Optic Nerves, cut at their union.

G. The Corpora Albicantia ; the Infundihulum is seen betwixt these and

the optic nerves.
H. H. The Crura Cerebri.
I. The Pons Varolii, or Tuberculum Annulare.

K. The Eminences of the Medulla Oblongata, called Corpora Pyramidalia.
L. The Corpora Olivaria.

Arteries.

1. 2. The Right and Left Carotid Arteries, raised with the brain, and cut
off as they rise at the point marked in the preceding Plate ; that is, as
they rise at the side of the sella turcica.

3. 4. The Right and Left Vertebral Arteries.

5. The Union of the Vertebral Arteries to form the Basilar Artery.

6. The communicating Artery, or Anastomosis betwixt the Basilar Artery

and Carotid.

7. The Union of Communication betwixt the carotids of each side by the

anterior arteries of the cerebrum ; these anastomoses, 6 and 7, form
tlie Circle of Willis.

Divisions of the Internal Carotid Artery.

8. The Middle Artery of the Brain passing into the Fissura Sylvii.

9. The Anterior Artery of the Cerebrum.

* The arteria communicans is also considered as a branch of the Internal
Carotid. The arrangement here alluded to is very remarkable. As the
branches which pass off laterally from the single trunk of the Basilar Artery
are united to the Internal Carotids, and the Internal Carotids are united to each
other, there is an uninterrupted continuation of artery, which encloses a
portion of space of a determined form ; but this form resembles an oblong
square more than a circle. By this connexion, blood will pass from any one of
the four arteries of the brain to all the others.

. CERVICAL ARTERIES. 269

Branches of the Vertebral and Basilar Arteries.

10. The Posterior Artery of the Cerebellum which comes from the Vertebral.

11. A very considerable branch of the Basilar Artery to the Pons
Varolii and Cerebellum, which, however, has no name.

12. The Anterior Artery of the Cerebellum.

13. The Posterior Artery of the Cerebrum.

The lesser branches of vessels seen in this Plate are mentioned in the
text, but are not distinguished by any particular name.

The Superior Intercostal Artery

Arises from the upper part of the Subclavian, after the
Vertebral and Thyroid arteries, and very near them. It
descends by the side of the spine across the first and second
ribs, near their heads, and exterior to the great intercostal
nerve. It generally forms two branches, which are appropri-
ated to the muscles, &c., in the first and second intercostal
spaces, and sometimes a small branch is continued to the third
intercostal space. From each of these branches a small vessel
proceeds backwards, and is spent upon the contiguous muscles,
on the back of the thorax. The Intercostal Artery also
sends a branch upwards to the deep-seated parts of the
neck.

In addition to the arteries above mentioned, there are several
others of considerable size which originate either directly or
indirectly from the Subclavian, and are spent upon the lower
portion of the neck and the contiguous parts. These arteries
are very different in different subjects, especially as to their
origin. Two of them, which have been called the Anterior
and Posterior Cervicals, are generally distributed to the muscles
and other parts which lie on the lower portion of the neck ante-
riorly and posteriorly.

A third, which passes transversely on the lower part of the
neck, is called the Superior Scapular.

In some cases, the two Cervical Arteries arise from the

subclavian, after the mammary and the thyroid, in a common

trunk which soon divides. Very frequently they go oft' from

the Inferior Thyroid. Sometimes one of them goes off" from

23*

/270 SUBCLAVIAN AXILLARY.

the Inferior Thyroid and the other from one of the branches of
the Subdaviaji.'*

The Superior Scapular most commonly arises with some
other artery, and very often from the Inferior Thyroid. It runs
transversely outwards within and above the clavicle, and passing
through the notch in the upper costa of the scapula, divides
into branches which are distributed to the parts on the dorsum
of that bone.

The Subclavian Artery, in its progress from the aorta to the
axilla, forms an arch or curve, over the fifth rib, as has been
already observed. The anterior scalenus muscle is before it,
and the great nerves of the upper extremity are above it. After
passing between the scaleni, it descends upon the first and
second rib into the axilla. The nerves which are above descend
with it ; at first they are necessarily exterior to it ; but they
form a plexus which the artery enters into, so as to be partly
surrounded by them. This course of the artery is obliquely
under the clavicle, and behind the pectoral muscle. In the
axilla, the vessel and nerves which surround it are placed be-
tween the tendons of the pectoralis and the latissimus dorsi
muscles. Here the artery takes the name of Axillary, and
sends off several important branches.

The principal branches that go off from the axillary artery
are distributed,

1st. Anteriorly, to the pectoral muscle, and the parts on the
anterior surface of the thorax.

2d. Posteriorly to the muscles which are on the scapula and
contiguous to it ; and

3d. To the parts which are near the upper extremity of the
OS humeri.

* Haller paid ^reat attention to the arterial system, and made many dissec-
tions, with a view to engravings of it, which he published with descriptions in
folio fasciculi.

These fasciculi have been collected, and, with some other engravings, form a
large volume, entitled icones ANATOMiciE, which is truly valuable.

There are some very interesting observations on this work of Haller's, and
also on these arteries, in a description of the arteries, by Dr. Barclay, of
Edinburgh, which I have read with advantage, as well as a Work on the mus-
cles by the same author.

BRANCHES OF THE AXILLARY ARTERY. 271

Anterior Branches,

The arteries which go to the pectoral muscle, &;c., are very
various in different subjects, both as to their number, origin and
size.

They have been called by different names, as Thoradcce
Externce, Mammaria Externa, &tc.

There are almost always three of them, and very often more:
one of them, which is called by several authors the Acromialis,
proceeds towards the end of the clavicle, and generally passes
out at the interval between the deltoid and the pectoral muscle,
sending various branches to the contiguous parts ; the largest
of its branches often passing in the direction of the interstice
between those muscles.

Another of these arteries, which is called Superior Thoracic,
is generally very small : it often is a branch of the above men-
tioned Acromialis.

There is very often to be found here an artery called the
Inferior Thoracic, or the External Mammary, which is of
considerable length, although its diameter is not very great.
This artery originates near the two last mentioned, and some-
times from the Acromialis. It often extends downwards as
low as the sixth rib, and sends branches to the anterior part
of the thorax, to the mamma, and other contiguous parts.
Many of the small branches of this artery anastomose very
freely with those of the internal mammary.

There are always one or more small arterial branches in the
axilla, which ramify upon the glands and adipose matter always
existing there. They often arise by one common trunk, which
is called the Thoracica Axillaris.

Posterior Branch.

One large artery is commonly sent to the muscles on the
scapula, which is called the Scapular, the Common Scapular,
or the Internal Scapular. It commonly passes off from the
axillary after the thoracic arteries, and supplies the muscles

272 HUMERAL ARTERY.

on both surfaces of the scapula. This large vessel passes
downwards a short distance in the direction of the inferior
costa of the scapula, and soon sends off a branch that winds
round to the dorsum of the bone, to be distributed to the infra-
spinatus and the contiguous muscles, which is called the Dor-
salis Scapula. The main trunk then inclines to the subscapu-
laris muscle, and generally divides into two branches, which
are distributed to the subscapularis, teres n)ajor, latissimus
dorsi, &-C.

Sometimes the Scapular artery divides into two branches
before it sends off the dorsal. In this case the last mentioned
artery goes off from one of those branches.

Branches near the Os Humeri.

The arteries which are near the body of the os humeri, at
its upper end, are generally two in number, and denominated
the Anterior and Posterior Circumjlex. Sometimes, they arise
separately, and sometimes in a common trunk from the axillary
artery. Frequently, one of them arises from the scapular.

The Anterior Circumjlex passes between the united heads
of the biceps and coraco-brachialis muscles and the body of
the OS humeri, at a small distance below its head. It sends
branches to the capsular ligament, the periosteum of the os
humeri, the membranes of the groove for the long head of the
biceps, the upper portions of the biceps and coraco-brachialis,
and some contiguous muscles.

The Posterior Circumjlex proceeds between the subscapu-
laris and teres major muscles, and continues between the os
humeri and the head of the triceps and the deltoides. It is dis-
tributed to the muscles and parts about the joint, especially to
the deltoides.

These arteries surround the os humeri, and the small branches
anastomose with each other. The Posterior Circumjlex is
much larger than the Anterior.

The great artery of the arm proceeds from the axilla to the
elbow ; and, during this course is generally denominated

BRANCHES OF THE HUMERAL ARTERY. 273

The Humeral Artery*

The direction of this artery is influenced by the position of the
OS humeri. When the arm hangs down, with the palm of the
hand presenting forward, this direction is somewhat spiral. The
situation of the artery is on the inside of the biceps muscle, and
between that muscle and the triceps extensor. It also continues
very near and on the inside of the tendon of the biceps, and
under the Aponeurosis which proceeds from that tendon. In
consequence of the spiral or oblique course of the artery, its
direction would be from the inside of the tendon of the biceps
to the radial side of the fore-arm ; but soon after it passes across
the joint of the elbow, it divides into two branches: one which
preserves, for some distance, the direction of the Main TrunJc,
is called the Radial artery : the other, which inclines obliquely
downwards and towards the ulna, is the Common Trunk of the
Ulnar and Interosseal Arteries.

During this course, the Humeral artery sends off several
branches to the muscles and other parts on the os humeri. The
largest of them is denominated the Profunda Humeri or Spi-
ralis. This artery very often arises as high as the insertion of
the latissimus dorsi, and passing between the heads of the tri-
ceps extensor muscle, proceeds downwards under that muscle
in a spiral direction, towards the external or radial condyle.
It sends several branches to the triceps and the contiguous
muscles, and one considerable branch, which is generally called
the Profunda Minor, to the parts contiguous to the internal
condyle. The ramifications of these branches near the condyle
frequently anastomose with small branches of the radial and
ulnar arteries.f

A small branch frequently arises from the Humeral artery, at
a short distance from the Profunda Humeri, •which sends a rami-
fication to the medullary foramen of the os humeri. This vessel
is, therefore, denominated Arteria Nutritia.

* It is called the Brachial Artery by several writers.

f The profunda sometimes originates from the scapular, or one of the cir-
cumflex. The profunda minor sometimes has a distinct and separate origin,
lower down than the other.

274 THE KADIAL ARTERY.

There are very often several anastomoses between the
branches of the Humeral artery which originate above the
elbow, and certain branches of the Radial and Ulnar arteries
which are called, from their direction, recurrents. Among these
arteries there is generally one of considerable size, which proceeds
across the elbow joint near the internal condyle. Sometimes
this is the ulnar recurrent, which goes up to anastomose with the
branches of the profunda ; but more frequently it is a separate
branch of the Humeral artery which goes off a little above the
elbow, and passes across the articulation, near the internal con-
dyle, to anastomose with the branches of the ulnar artery. This
artery is denominated the Anastomodca.

There are often other branches sent off by the Humeral
artery ; but they are commonly small, and very irregular.

The two great ramifications of the Humeral artery on the
fore-arm have very different directions. The Radial artery
preserving the course of the main trunk while the Common
Trmik of the Ulnar and Interosseal projects from it in a
direction downwards and towards the ulna, passing under the
pronator teres, &c.

The Radial Artery,

Passing over the pronator teres muscle, proceeds between
the supinator radii longus and the flexor carpi radialis, very near
to the lower end of the radius, without changing its direction
materially, being deep-seated above and superficial below ; it
then alters its course, and, passing under the tendons of the
extensors of the thumb, to the back part of the radius, it con-
tinues between the metacarpal bones of the thumb, and of the
index finger, when it divides into three branches.

In this course, it gives off but few branches. The first is the
Radical Recurrent, which passes upwards and towards the
external condyle, but frequently anastomoses with the ramifica-
tions of the profunda humeri.

The branches which it sends off between the origin of the
recurrent and the lower end of the radius, are generally very
small, and distributed to the parts immediately contiguous to

ULNAR ARTERY. 275

the artery. Before it turns under the tendons of tlie extensors
of the thumb, it sends a branch over the wrist called dorsalis
carpi radialis towards the root of the thumb, from which pro-
ceeds a branch to anastomose with the volar branch of the
ulnar ; and another, not so large, named anterior carpi radialis
which is frequently continued on the radial or external side of
the thumb, very near to its extremity. While the radial artery
is under the aforesaid tendons, it sends off small branches to
the back of the wrist and back of the hand, meiacarpal
branches, and two to the back of the thumb called dorsales
poUicis. Those which are distributed to the wrist and back of
the hand, generally anastomose with the small branches of the
ulnar and interosseal arteries.

The three branches into which the radial artery divides be-
tween the metacarpal bones of the thumb and index are, 1st, a
branch to the external sides of the index fingers (radialis indicis) ;
2dly, a branch to the thumb, that sometimes divides into two,
which pass up on the anterior or volar surface, aud sometimes
continue, without much diminution, on the internal side of the
thumb, near to the end of the last phalanx ; this is called the
superficialis voice, and seems from its direction, though not
from its size, to be the proper continuation of the radial artery.
Occasionally, however, it is met with of such large size, that
when cut it gives rise to troublesome hemorrhage ; and, 3dly, a
branch called Palmaris Profunda, which dips down into the
palm of the hand, and proceeding in contact with the metacar-
pal bone, under the flexor tendons, &;c., forms an arch which
extends across the hand, and often terminates by anastomoses
with another but more superficial arch, soon to be described,
which is formed by the ulnar artery. —

This flexure, which is denominated Arciis Profundus, sends
off branches of a very small size, which are distributed to the
bones, ligaments, muscles, &;c., contiguous to it.

The Common Trunk of the Ulnar and Interosseal Arteries
Passes under several of the muscles which originate from

276 THE INTEROSSEAL ARTERY.

the internal condyle, and between the flexor sublimis and the
flexor profundus. Before the Ulnar Recurrent goes off from
this vessel, the interosseal artery often leaves it. This recur-
rent artery passes upwards between the muscles of the inter-
nal condyle, and distributes branches among them. It then
passes up in the groove behind the internal condyle, and anas-
tomoses with the branches of the Anastomotica or Profunda
Humeri.

The ulnar and interosseal arteries separate from each other
at the distance of fifteen or twenty lines from the origin of the
radial artery, very near the commencement of the interosseal
ligament.

The Interosseal Artery,

In a majority of cases, arises in a single branch from the
common trunk of the ulnar and interosseal. When it does so,
the single branch soon sends off the Posterior Interosseal arlery,
which perforates the interosseous ligament, and passes down
on its posterior surface, while the main branch continues on
the anterior surface of the ligament, and is denominated the
Anterior Interosseal Artery. In some cases, the main branch
proceeds on the anterior surface as low as the upper edge of
the pronator quadratus muscle, before it sends off the poste-
rior branch. Sometimes the anterior and posterior interosseals
arise separately. In this case the posterior soon perforates the
ligament.

The Anterior Interosseal passes down almost in contact with
the ligament, and gives branches to the contiguous parts in its
course. It generally perforates the interosseous ligament near
the wrist, and sends off many small branches to the back of
the wrist and hand, which anastomose with the small branches
of the radial and the posterior interosseal arteries.

The Posterior Interosseal soon gives off a recurrent or anas-
tomosing branch, and then proceeds downwards towards the
wrist, sending branches in its course to the extensor muscles and
tendons.

This vessel sometimes divides into two branches.

ULNAR ARTERY. DIGITAL ARTERIES. 277

The Ulnar Artery.

The Ulnar artery proceeds among the muscles obliquely
downwards guided as it were by the flexor ulnaris, and is not
superficial until it has arrived within three or four inches of
the carpus : it then continues towards the hand, sending off
very small branches in its progress. It passes over the annular
ligament at the wrist, and winds round the pisiform bone:
here it is supported by a delicate ligament, which seems to lie
upon it : from this it passes upon the palm of the hand, under
the aponeurosis palmaris, and over the tendons of the flexors
of the fingers. When thus situated, it forms, in perhaps a
majority of subjects, an arch or bow, called Arcus Sublimis,
which extends across the palm of the hand, from the ulnar
towards the radial edge, and, after sending branches to the
fingers, from its convex side, terminates near the root of
the thumb, by anastomoses with that important branch of the
radial artery, {super Jicia lis volae) which passes up on the inside
of the thumb. The Arcus Sublimis almost always sends off
small branches, to the integuments, &c., on the palm of the
hand. It sends off, near the root of the metacarpal bone of
the little finger, a branch which passes between the flexor ten-
dons and the metacarpal bones, and anastomoses with the Arcus
Profundus. It then generally sends off a branch to the inner
or ulnar side of the little finger ; and afterwards three branches
in succession, which pass from its convex side towards the
angles formed by the fingers. These are called

The Digital Arteries.

When they have arrived near to the heads of the first pha-
langes of the fingers, each of these arteries divides into two
branches, one of which passes along the side of one of the fin-
gers to its extremity, and the other on the opposite side of the
next finger : and in this way they pass on the sides of all the
fingers, except the inside of the little finger, and the outside of
the index which are supplied from the radial artery.

These branches of the digital arteries are called Digiio-Radial
VOL. II. 24

^78 ARTEKIES OF THE ARM.

and Digito-Ulnar arteries, according to the sides of the fingers
on which they are placed. They are situated on the angle,
if it may be so termed, which is formed by the anterior and
lateral surfaces of each finger. In their course from the basis
to the extremity of the finger, they send off very small trans-
verse branches, which anastomose with each other, especially
near the end. Some transverse branches are observable on the
posterior as well as the anterior surface. Near the extremity
of each finger, beyond the insertion of the flexor tendon,
the extremities of these arteries ramify minutely. Some of
these small branches go to the skin and others anastomose with
their fellows of the opposite side. Some also go to the back
of the fingers.*

Of the Arteries of the Arm, (see Plate VI. facing page 279.)

A. The Scapula.

B. The Pectoral Muscle held up.
c. The Deltoid Muscle.

D. The Biceps Muscle.

E. The Coraco-brachialis Muscle.

F. The Triceps Extensor Muscle.

G. The Teres Major.

H. The Tendon of the Lesser Pectoral Muscle.

I. The Supinator Longus.

K. The Extensor Carpi Radialis.

L. The Flexor Carpi Ulnaris.

M, The Palmaris Longus and Flexor Muscles of the Fingers.

* The distribution of the radial and ulnar arteries in the hand,, is very differ-
ent in different subjects.

Upon examining a large number of injected preparations in Philadelphia, it
was found that, in a very small majority of them, the ulnar artery formed an
arcus sublimis, whose branches extended as far as the ulnar side of the index,
and sometimes beyond it.

That, in near a third of the preparations, the ulnar artery ramified without
forming an arcus, and supplied only two of the digital branches, viz., the first
two on the ulnar side. In such cases the radial artery generally made up the
deficiency of the ulnar, but in a few instances the interosseal was extended on
the palm of the hand, and supplied the radial side of the middle finger and the
corresponding side of the index.

In a few instances also the ulnar artery was still more deficient, and the
radial was proportionally extended.

f'f.,/,- 17

BRANCHES OF THE SUBCLAVIAN AND AXILLARY. 279

From the Aorta till the Artery passes over the first rib, it is called,

1. The Subclavian Artery. When this artery is injected, and tolerably full, it
makes two pretty acute turns, in the form of an italic <S, before it escapes
under the clavicle. Its larger curve is just where it comes through the
anterior and middle Scaleni muscles. It then descends directly across the
first rib. It next comes out under the clavicle, three fingers' breadth from
the inner extremity of the clavicle. Just at this point, viz. Avhere it
passes over the bulging of the rib, it may be compressed in the living body.
Its branches are,

2. The Internal Mammary Artery.*

3. The Vertebral Artery.

4. The Thyroid Artery.

5. The Ascending Thyroid Artery, a branch of the last. The Trans-
versalis Colli, or Cervicalis Posterior, is also generally a branch of
the Thyroid, very irregular in its origin. Sometimes it comes from
the Thyroid, and then receives the name of Transversalis Humeri;
sometimes it comes from the place of the Cervicalis Superjicialis , or
even from the Subscapularis ; sometimes from the Subclavian itself.

The Deep and Superficial Cervical Arteries,

6. The Supra Scapular Artery.
The Axilla.

7. The Trunk now assumes the name of Axillary Artery. Its branches
are three or four to the chest ; three to the scapula and shoulder.

8. The Lesser Superior Intercostal Artery, or Superior Thoracic Artery.

9. The Greater or Longer Thoracic Artery, or External Mammary
Artery.

10. The Thoracica Acromialis, or Humeraria.

The Thoracica Axillaris is not seen in this subject.

11. The Subscapular Artery ; it is seen to divide upon the edge of the
Scapula, into a deeper and a more superficial branch.

12. The Posterior Circumflex Artery of the arm.

13. The Anterior Circumflex Artery of the arm.
In the Arm.

14. The Trunk now assumes the name of Humeral Artery ; it gives off
These branches :

15. The Superior, or Greater Profunda.

16. The Lesser Profunda.

* Branches of the Internal Mammary Artery. 1. To the Thymus Gland. 2.
Accompanying the Phrenic Nerve. 3. To the Pericardium. 4. To the
Mediastinum. 5. Several branches to the Pectoral Muscle and Mamma. 6.
To the Diaphragm. 7. To the Abdominal Muscles, inosculating with the Epi-
gastric Artery. If a thrust be made with a small sword in any part (below
the second rib) in a line parallel with the Sternum, and three-fourths of an inch
from its edge, it will wound the Internal Mammary Artery.

280 BRANCHES OF THE BRACHIAL OR HUMERAL ARTERY.

17. The Anastoinoticus Major; the lesser anastomosing branch comes
off higher up, and follows the same direction round the inner condyle.

Arteries of the Fore-Arm.

Extremity of the Humeral Artery. The Artery divides three-fourths
of an inch below the part of the Median Basilic Vein, where we
generally bleed.

18. 18. The Radial Artery.

19. 19. The Ulnar Artery.

The Interosseous Artery, which divides into the Inner and
Outer Interosseous.
The Recurrent Arteries from these last are, the
Recurrens Radialis Anterior.
Recurrens Ulnaris Anterior.
Recurrens Ulnaris Posterior.
Recurrens Interossea.

20. At this point the Radial Artery turns under the supinator tendon

and the extensor tendons of the thumb.
Superficial Artery of the Palm.

21. The Ulnar Artery passing over the wrist.
Dorsalis Ulnaris.

Arteria Palmaris Profunda Ulnaris.

22. The Great Palmar Arch, from which the Arteries of the fingers

are seen to proceed.

23. This dotted line marks the seat of the Lesser Arch under the tendons.

From this sketch of the arteries we can follow in idea their continued
course among the muscles.

FIG. IT.
Termination of the Radial Artery as seen on the Plate oppo-
site (from Bell.)

A. Arteria Radialis.

B. Ramus Dorsalis.

c. Palmaris Profunda.

D. Ramus ad Indicem.

E. Ramus ad Pollicem.

BRONCHIAL AND (ESOPHAGEAL ARTERIES. 281

Of the Branches ivhich go off between the Arch and the great
Bifurcation of the Aorta.

PART 1.

In the Cavity of the Thorax.

The aorta while in the cavity of the cheek sends branches to
the pericardium, lungs, to the oesophagus, and to the parietes of
the thorax.

The Pericardial Branches,

— Are some small and very irregular vessels which are directed
forwards and ramify on the pericardium and posterior medias-
tinum.—

The Bronchial Arteries

Are the vessels which go from the aorta to the ramifications
of the trachea, and the substance of the lungs. They are not
large, and are very irregular as to their number and origin.

In a majority of cases the right lung is supplied, in part, by
a branch from the first aortic intercostal of that side ; while the
left lung receives two or three branches ffom the aorta directly.
In some cases a large vessel arises from the aorta, which divides
into two branches, one of which goes to each lung.

The Bronchial arteries frequently send small branches to the
posterior mediastinum, the pericardium, Slc.

Injections have shown, that there is a direct communication
between these vessels and the branches of the pulmonary
artery.

— They are the proper nutritious arteries to the substance of the
lungs and accompany the ramifications of the bronchia. —

The (Esophageal Arteries

Are very small vessels, which generally arise from the aorta,
but sometimes are branches of the bronchials or intercostals
that are spent upon the cesophagus. They occur in succession,

24*

282 INTERCOSTAL ARTERIES.

and sometimes are five or six in number. They also send twigs
to the contiguous parts ; — the lowermost descend to the stomach,
to anastomose with branches from the coronary artery of that
organ ; the upper ones communicate with branches of the infe-
rior thyroid. —

The Inferior Intercostals

Are the arteries which proceed directly from the aorta to the
parietes of the thorax. Their name is derived from their posi-
tion between the ribs. They are ramified on the intercostal
muscles and ribs, and on the pleura and some of the contigu-
ous parts. They are called Inferior or Aortic Intercostals, to
distinguish them from the superior intercostals, which are
derived from the subclavian artery. Their number varies from
ten to eight, according as the superior intercostals are more or
less numerous.

— There are usually eight on the left side and ten on the
right. —

They originate in pairs on the posterior surface of the aorta.
The uppermost of them pass obliquely upwards, and the lower-
most nearly in a horizontal direction, to the lower edges of
those ribs to which 'they are appropriated. They meet the
rib near its tubercles, or place of junction with the transverse
process of the vertebra, and then proceed forward, between
the internal and external intercostal muscles, in a superficial
but large groove, which is generally to be found on the interior
margin of the lower surface of the rib.* There is necessarily
a difference in the length of the right and left intercostals,
owing to the position of the aorta, which is rather on the left
of the spine. In consequence of this circumstance, the (Esoph-
agus is anterior to, and also in contact with those of the right
side.

They generally send off an important branch, called the
Dorsal, which arises near their origin, and, passing backwards,
sends ramifications to the muscles of the back. From this

* See Vol. i. page 155.

^itANCHES OF AORTA IN THE CAVITY OF THE ABDOMEN. 283

dorsal branch also proceeds a ramification, which enters the
spinal cavity, and is spent upon its membrane and upon the
medulla spinalis.

After the Intercostals in their progress forward, have passed
beyond the middle of the ribs, they send off a branch, which
generally proceeds very near to the upper side of the lower rib.
The main trunk generally leaves the lower edge of the rib when
it has arrived within one-third of the length of the bone from
its anterior extremity. It then generally divides into several
branches, some of which are spent upon the pleura, and others
on the intercostal and the contiguous muscles.

According to the situation of the different intercostals, some
of their ramifications, communicate with those of the internal
and external mammaries, of the phrenic, the lumbar, or the
epigastric arteries.

PART 2.

In the Cavity of the Abdomen.

The Aorta passes into the cavity of the abdomen between
the crura of the diaphragm, as has been already mentioned.
In its course from the crura to its great bifurcation, it sends off
one pair of small arteries, called Phrenic, to the diaphragm.
Three single arteries, the Cceliac, the Superior and the Inferior
mesenteric, to the viscera of the abdomen. A pair of large
arteries, the EmuJgents, to the kidneys, with several that are
very small to their appendages ; as the Spermatics, Capsular,
the Ureteric, and the Adipose. In addition to these, there is
one pair of small arteries that go to the testicles in the male, or
to the ovaria and the uterus in the female, and four or five
pairs, called Lumbar Arteries, that go off laterally, like the in-
tercostals, to the parietes of the abdomen, and to the muscles
on the back, which are contiguous to them.

284 PHRENIC ARTERIES.

Representation of the Diaphragm, the Situation of the Heart,
the Blood-vessels of the Breast, and Abdominal Aorta. (See
Plate VII. facing page 284.)

A. The Diaphragm, dividing the thorax from the ahdomen.

B. The Heart, lying upon the diaphragm, and with the apex obliquely to

the left side.
c. The Riffht Ajiride.

D. The Left Auricle ; that which receives the blood from the lungs.

E. The Superior Vena Cava, returning the blood from the arms and head to

the right auricle.

F. The Arch of the Aorta.

G. The Puhnonary Artery.

H. H. The Right and Left Carotid Artery.

I. The Subclavian Artery.

K. The Liternal Mammary Artery.

L. The Thyroid Artery, to the shoulder, the neck, and the thyroid gland.

M. The Vertebral Artery.

N. The Lungs of the right side.

0. The Perforation of the Diaphragm, for the transmission of the inferior

cava,
p. The Hole by which the CEsophagus passes into the abdomen.
Q. The lesser Muscle of the Diaphragm. See the text, p. 344, vol. i.
R. s. The whole length of the Abdominal Aorta. It is seen embraced by

the diaphragm at e, and immediately giving off the phrenic and cceliac

arteries.

1 . The Right Phrenic Artery.

2. The Left Phrenic Artery.

3. The Root of the CoRliac Artery.

4. 4. The Upper Mesenteric Artery.

5. 5. The Emulgent Arteries.

6. The Loiver Mesenteric Artery.

7. The Superior Hcemorrhoidal Artery, a branch of the last.

8. 8. The Common Iliac Arteries.

9. The Internal Iliac. It is seen to give off the gluteal, the ischiatic, and

the obturator artery.

The Phrenic Arteries

Are ramified on the concave surface of the diaphragm, and
are almost always two in number; they are denominated right
and left from their position. They commonly originate sepa-
rately from the aorta, but sometimes they arise in a common

J'hitc JJ.

' /i,//,A/.

^. (~-'<//ffi/ .KY^///^

DISTRIBUTION OF THE CffiLIAC AKTERY. 285

trunk which soon divides. In some instances they are derived
from the coeliac. In a few cases the aorta furnishes one, and
the coelic the other. Each of the phrenic arteries commonly
crosses the crus bf the diaphragm on its respective side, and
proceeding laterally, in a circular direction, often ramifies so as
to form an internal and external branch. Each of them gene-
rally sends branches to the cardia or oesophagus, to the glan-
dulae renales, and other contiguous parts.

Distribution of the Cceliac Artery (^See Plate VIII. facing

page 286.)

A. The Liver raised so as to show its concave surface.

B. The Gall Bladder.

c. The Stomach laid down to the left side.

D. The Omentum.

E. The Colon.

F. The Small Intestines.

1. The Aorta.

2. The Root of the Cceliac Artery.

3. The Superior Coronary Artery of the Stomach.

4. The Splenic Artery.

5. The Gastro-Epiploic Artery.

6. The same Artery running upon the Great Arch of the Stomach.

7. The Pancreatica Duodenalis, a branch of the last,

8. The Hepatic Artery ; it is seen to divide into the right and left hepatic
arteries ; the right hepatic artery is seen to give off the Cystic Artery ; a
small branch is seen passing from the trunk of the hepatic artery to the
Pylorus, viz. the Lower Pyloric Artery.

The Coeliac Artery ( Cceliac axis)

Is the first great branch given off by the aorta in the abdo-
men, and is distributed almost entirely to the stomach, the liver
and the spleen. It projects from the anterior part of the aorta
so as to form a right angle with it, and is of course nearly hori-
zontal, when the body is erect.

The main trunk of this great artery is so remarkably short,
that it has been compared to the stump of a tree ; for, at the
distance of half an inch from its origin, it generally divides into
three branches, which pass to the stomach, the liver, and the

286 GASTRIC OR CORONARY ARTERY.

spleen, and are, therefore, denominated the gastric or Coronary,
the HEPATIC and the splenic arteries.
The first branch of the Cccliac is called

The Superior Coronary or Gastric Artery,

To distinguish it from the other branches, soon to be described.
It is commonly in the centre of the three great ramifications of
the ccsliac, and is also the smallest of them. It proceeds from
its origin to the upper orifice of the stomach or cardia, and con-
tinues thence along the lesser curvature of that viscus until it
approaches near to the pylorus. In this course it sends
branches to the oesophagus, which frequently inosculate with
the oesophageal arteries. It also furnishes branches to the
cardia, which partially surround it ; and, on this account, the
artery has been called Coronary. Some of these last mentioned
branches are often continued on the great extremity of the
stomach, and anastomose with those ramifications of the splenic
artery, called Vasa Brevia.

It continues on the lesser curvature between the lamina of
the small omentum, and sends off successively branches which
pass between the peritoneal and muscular coats, and are dis-
tributed to the anterior and posterior surfaces of the stomach,
communicating with the branches of the inferior gastric arteries,
soon to be described.*

The Hepatic Artery

Proceeds from the great ramification of the coeliac to the
transverse fissure of the liver called the Portce, in which it
generally divides into two branches. In this course it very
frequently sends off an artery to the pylorus, which ramifies
about the small extremity of the stomach, and often inosculates
with some of the branches of the superior coronary. This
branch is called the Pyhrica, and sometimes it arises from the
artery next to be mentioned.

* This artery sometimes sends a branch to the liver, When this is the case,
it is always very large.

THE SPLENIC ARTERY. 287

The Gastrica Inferior Dextra,

Which also generally originates from the main trunk of the
hepatic, but sometimes from one of its branches. It is an
artery of considerable size, which proceeds along the great
curvature of the stomach, from the pylorus towards the great
extremity between the lamina of the anterior portion of the
omentum, and distributes its ramifications to both sides of the
stomach, and also to the Omentum. In its progress from the
hepatic artery to the stomach, it sends off branches to the Duo-
denum and to the right end of the Pancreas.

The two great branches into which the hepatic artery
divides, are denominated right and left, from the lobes of the
viscus to which they are respectively appropriated. The right
branch is the largest. Before it penetrates the substance of the
liver, it sends off a branch to the gall-bladder, called the Cystic
Artery.

The branches of the hepatic artery ramify very minutely in
the liver, as has been stated in the account of that organ.

The last great branch of the coeliac is

The Splenic Artery,

Which is generally found larger than the hepatic in adults,
although it is less in children. It proceeds in a transverse
direction from its origin to the spleen : its course is not
straight, but meandering or serpentine. It is situated behind
and above the pancreas, and passes along the groove in the
upper edge of that viscus. In its progress, it sends off many
small branches, and one that is of considerable size, called
pancreaticus magnus, to the Pancreas. It also sends one
branch to the left extremity of the stomach, which arises com-
monly from the main trunk, but sometimes from the ramifica-
tions, which are soon to be mentioned. This branch, which is
called

The Gastrica Inferior Sinistra,

Or left gastro-epiploic artery is sometimes, but not often very
large : its course is from left to right, along the great curvature

288 SUPERIOR MESENTERIC ARTERY.

of the Stomach. It is situated between the lamina of the ante-
rior portion of the omentum. It sends some small branches to
the omentum, and others which are larger and more numerous,
to both sides of the stomach. Some of these last mentioned
anastomose with the ramifications of the gastrica dextra which
come from the hepatic.

When the Splenic artery approaches near to the spleen, it
divides into four, five, or six branches, each of which pene-
trates into that viscus by a distinct foramen, and then ramifies
in the manner described in the account of the structure of the
spleen.*

Either from the splenic artery, or from these ramifications,
four or five branches pass to the large extremity of the stomach
and ramify there, communicating with the vessels already
described. These arteries have received great attention from
physiologists, and are denominated Vasa Brevia.

The Superior Mesenteric,

Which is the second great branch given off in the abdomen
by the aorta, is not very different in size from the coeliac, and
originates about half an inch below it. It is distributed to the
small intestines ; to that portion of the great intestine which is
situated on the right side of the abdomen ; and to the arch of
the colon. From its origin it proceeds downwards, under the
pancreas, and over the lower portion of the duodenum, to
the commencement of the mesentery. When it has arrived
between the lamina of that membrane, it descends in a direction
which corresponds with that of the root of the mesentery,! and
forms a gentle curve, with its convexity directed towards the
intestines. It necessarily diminishes as it ascends, and gene-
rally terminates by anastomosing with one of its own branches.
This great artery sends off some very small ramifications to the
pancreas and the duodenum, while it is in their vicinity. It
also sends two or three branches to the transverse part of the

* Ic frequently happens that the splenic artery divides only into two or three
branches, and they subdivide so as to form five or six, which penetrate the
spleen.

t Vol. li. p. 110.

INFERIOR MESENTERIC ARTERY. 289

colon, to the right portion of the colon, to the beginning of the
great intestine, and the contiguous portion of the ileon. These
branches are commonly termed the Colica Media, Colica Dex-
tra, and lleo Colica. From the convex side of the curve, the
superior mesenteric sends off the important branches which
pass between the lamina of the mesentery, and supply the
Small Intestines. These branches are numerous, and many of
their ramifications anastomose with each other, so as to form
arches. From these arches go off other branches, which anas-
tomose again with some of similar origin to form other arches,
which are much more numerous than the first set ; and
this process is repeated successively several times, so that a
net-work of blood-vessels seems to be formed on the mesentery.
From the mesentery the small ramifications are continued, in
great numbers, to the intestines. Some of them anastomose
with each other on the coats of the intestine ; but an immense
number of minute arteries are continued to the villous coat, so
that, when they are successfully injected, the surface of that
coat appears uniformly colored by the injection.*

The Inferior Mesenteric Artery

Does not go off from the aorta next in order after the superior
mesenteric, but succeeds it immediately on the intestines, and
continues the arterial ramifications to the left portion of the
colon, to which the branches of the superior mesenteric do not
extend.

This artery arises between the origin of the emulgents and
the great bifurcation of the aorta, and proceeds downwards,
inclining to the left, but keeping near to the aorta. There are
generally three branches distributed to the left portion of the
colon, which arise from this artery, either separately, or by a
common trunk which soon divides. It frequently happens, that
one of these arteries arises separately, and two by a common
trunk. These are called the Left Colic arteries ; and are also
sometimes denominated, from their position, Superior, Middle,

* See the account of the termination of these arterieS; at page 46 of this
volume.

VOL. II. 25

.A

290 DISTRIBUTION OF THE MESENTERIC ARTERIES.

and Inferior. The Superior generally anastomoses with that
branch of the superior mesenteric, which is called Colica Media,
and forms a remarkable arch, called the Great Mesecolic Arch.
The ramifications of the other branches frequently anastomose
with each other, and are finally spent upon the left portion of
the colon.

The main trunk, diminished by sending off these branches,
but still of considerable size, runs downwards on the posterior
part of the intestinum rectum, between that intestine and the
sacrum, where it often divides into two branches, which con-
tinue near to the termination of the rectum. From them proceed
many ramifications that are spent upon the rectum. Some of
these ramifications anastomose with each other, and others with
the branches of the haemorrhoidal artery, soon to be mentioned.

Distribution of the Mesenteric Arteries, (see Plate XI. facing

page 290.)

A. A. The Omentum held up, and bearing the great Arch of the Colon.

B. The termination of the Intestinum Heon in the Caput Coli.
c. Captit Coli.

D. E. The Arch of the Colon, which stretches across the belly.

F. The Sigmoid Flexure of the Colon.

G. The Rectum.

H. The Bladder of Urine.

1. The Aorta.

2. The Coeliac Artery.

3. The root of the Upfer Mesenteric Artery.

4. The great Lash of Arteries which go to the small intestines.

5. T\\e Ileo- Colic Artery .

6. The Right Colic Artery.

7. The Middle Colic Artery.

8. The Lower Mesenteric Artery.

9. The Left Colic Artery ; this forming a great inosculation betwixt the
Upper and Lower Mesenteric Arteries.

10. The Hcemorrhoidal Artery descending with the Rectum into the Pelvis.

11. The Emulgcnt Artery of the left side.

12. The Spermatic Artery.

13. The Middle Sacral Artery.

14. The Common Iliac Artery.

15. The External Iliac Artery.

16. The Internal Iliac Artery.

n<x^^i 17//.

Cy. /■,/„■/„ .„»//,.

EMULGENT, CAPSULAR, AND ADIPOSE ARTERIES. 291

The Emulgent or Renal Arteries

Are the large vessels which pass from the aorta to the kid-
neys. They arise between the superior and inferior mesenteries
one on each side ; and proceed in a direction which is nearly
rectangular to the aorta. The right emulgent artery is neces-
sarily longer than the left, and it generally passes behind the
vena cava. When they approach near the concave edges of
the kidneys, each emulgent commonly divides into three or
four branches, which pass into the fissure of that organ, and
ramify in the manner described in the account of it. Some-
times two arteries proceed from the aorta to the kidney ; but
this is not a frequent occurrence.

The Capsular or Supra-renal Arteries

Are the small vessels which pass to the glandulae renales.
There are almost always two or more of them appropriated to
each gland. They often arise on each side from the coeliac
artery, or from the emulgent, but more usually they come off
from the aorta.

The Adipose Arteries

Supply the adipose substance surrounding the kidneys.
There are several of them on each side, and, like the last men-
tioned arteries, they are very small, and arise from several
sources as well as from the aorta.

The testicles and ovaries are supplied by the

Spermatic Arteries,

Which are very remarkable for their great length and small
diameter. In a majority of cases, these vessels arise from the
anterior surface of the aorta, a little below the emulgents : but
it often happens that the left spermatic arises from the emul-
gent on that side. They also sometimes arise from other
neighboring arteries. It has been observed, when they arise
from the aorta, that the origin of one of them is generally
hisher than that of the other.

292 SPERMATIC ARTERIES. LUMBAR ARTERIES.

They pass downwards, so as to form an acute angle with
the aorta, and proceed behind the peritoneum, and before the
psoas muscle and ureter. While this artery is in contact
with the psoas muscle, it meets with the ramifications of the
spermatic vein, and, in its progress to the abdominal ring, also
joins the spermatic cord. In this course it sends off some very
small twigs to the contiguous parts, and others that anastomose
with similar ramifications from the mesenteric, epigastric, &tc.
Before it arrives at the testicle, it divides into several branches,
two of which generally go to the epididymis, and the others
penetrate the upper and back part of the tunica albuginea.

The Sperm,atic Arteries in the Female,

Instead of passing to the abdominal ring, proceed between
the lamina of the broad ligaments, and send branches to the
ovaria, which, in some cases, may be traced to the Graafian
vesicles. They also send branches to the Fallopian tubes and
uterus, and to the round ligaments. Those which are on the
opposite sides of the uterus, anastomose with each other, and
with the branches of the hypogastric arteries.

The lumbar regions are supplied with arteries which origi-
nate like the intercostals, from the posterior part of the aorta
between the thorax and pelvis. There are four or five of these
vessels on each side, and they are denominated

The Lumbar Arteries.

They pass between the spine and the psoas muscle, and send
branches to the spinal cavity, to the muscles of the lumbar
regions, and the abdominal muscles. They anastomose with the
intercostals, the internal mammary, the epigastric, the circum-
flex of the ilium, and the ilio-lumbar. — They are analogous to
the intercostal arteries in regard to their mode of origin, direc-
tion, and size, and like them are intended for the supply of the
lateral parts of the trunk. —

— A small artery, about the size of a crow quill, passes off
singly from the posterior part of the aorta at its bifurcation,
which is called

^■'. ('\//ri>/ ■•'"//'■

>w/ ././.

ARTERIES OF THE PELVIS AND HAM. 293

The Middle Sacral Artery.

It proceeds over the last lumbar vertebrag and down the
middle of the sacrum to the os coccygis ; it sends off lateral
branches, which are spent upon the rectum and contiguous
parts, and inosculate with the arteriae sacrae laterales.

Of the Arteries which originate at and below the Great
Bifurcation of the Aorta.

The Primitive lliacs,

The terminal branches of the aorta, form an acute angle
with each other at their origin. They proceed downwards
behind the peritoneum, very near the margin of the pelvis,
without sending off any branch of importance. At the junction
of the sacrum with the ossa ilia, they divide into two great
branches: the Internal Iliac, or Hypogastric, which descends
into the pelvis ; and the External Iliac, which passes under the
crural arch to the lower extremity.

— Both of these vessels are crossed by the ureters just at their
point of division. The right is also crossed by the intestinum
ileum, where it is about to pass into the colon ; the left lies
behind the sigmoid flexure of the colon. —

Arteries of the Pelvis and Ham, (from Bell.) See Plate X.
facing page 293.

A. The body of the last Lumbar Vertebra sawn through.

B. The Sacrum.

c. Ischiatic Ligaments.

D. The Lumbar Muscles.

E. The Great Gluteus Muscle.

F. The Lesser Gluteus Muscle.

G. The Gracilis Muscle.

H. The Vastus Externus Muscle.
I. The Outer Hamstring Muscle ; i. e. the Biceps.

K. The Inner Hamstring Muscles ; i. e. the Semi-tendinosus and Semi-
membranosus.
L. L. The Triceps.

M. The Outer Condyle of the thigh bone.
25*

294 GENERAL ACCOUNT OF THE INTERNAL ILIAC.

N. The Inner Condyle.

0. The Belly of the Gastrocnemius Muscle.

p. The Salens Muscle.

Q. The Achilles Tendon.

R. The Tibia.

s. The Flexor Longus Pollicis.

T. The Flexor Digitorum Communis.

1. The Internal Iliac Artery ; giving off.

2. Hypogastric Artery.

3. 3. Ischiatic Artery.
4.4. The Pudic Artery.
5. The Obturator Artery.
6.6. The Gluteal Artei-y.

7. A branch from the Internal Circumjkx Artery.

8. Branches of the Perforating Arteries of the Profunda.

9. The Popliteal Artery after it has pierced the Triceps Muscle.

10. Those branches sent off from the main artery as it is passing the ten-
don ; they are called the perforating branches of the Popliteal Artery.

11. The Upper and Internal Articular Artery.

12. The Upper External Articular Artery.

13. The Lower External Articular Artery. ^

14. The Lower Internal Articular Artery.

15. The Posterior Tibial Artery; the Anterior Tibial Artery (see plate,
page 308) is a branch sent off from this.

16. The Peroneal Artery, or Fibular Artery.

17. The Posterior Tibial Artery appears here again from under the Soleus
Muscle.

18. The Fibular or Peroneal Artery ; it is seen to form large inosculations
with the Tibial Artery.

19. A remarkable inosculation betwixt the Tibial and Fibular Arteries.

20. The External Plantar Artery.

21. The Internal Plantar Artery.

The Internal Iliac, or Hypogastric,

Is distributed, in part, to the viscera of the pelvis and the
orfyans of generation, and also to the large muscles exterior to
the pelvis : it is, therefore, very large, although not quite equal
to the External Iliac. — But in the foetus where it gives off on
each side the umbilical artery it is double the size of the exter-
nal.—

It has already been mentioned, that in the foetal state, this
vessel appears to continue in a curved direction from its origin

SMALLER BRANCHES OF THE INTERNAL ILIAC. 295

to the lower part of the side of the bladder, and from thence to
the umbilicus, under the denomination of the Umbilical Ar-
tery. From the convex side of this curve the different branches
of the internal iliac go off. In the foetal state they are very-
small, in proportion to the umbilical artery ; but as the artery
becomes ligamentous, these branches increase in size.

In the adult, the arrangement of these vessels is very differ-
ent. The Internal Iliac generally divides into two great
branches ; the Gluteal, which passes through the sacro-sciatic
notch, and ramifies on the exterior and upper part of the os
ilium : and the Ischiatic, which passes downwards on the out-
side of the tuberosity of the ischium.

The former of these large ramifications passes out of the pel-
vis above the pyriform muscle, and the latter of them below it.
Several smaller arteries arise from these branches near their
origin, or from the main trunk of the internal iliac, which are
distributed to the different parts of the pelvis ; and one im-
portant branch of the ischiatic, called the Pudic, proceeds
downwards on the inside of the tuberosity of the ischium.

The first of the smaller branches which the external iliac
commonly sends off, is called the

Ileo Lumbalis.

The ilio-lumbar artery sometimes arises from the gluteal
artery, and sometimes from the main trunk of the internal iliac.
It passes outwards under the psoas muscle, and suddenly
divides into two branches. One of them proceeds upwards,
and is distributed in the lumbar region, while the other ramifies
on the iliacus internus muscle, and is spent on the contiguous
parts.

There are, also, two or three small arteries called

Arteria Sacra Laterales,

Which sometimes arise singly, and sometimes in common,
from the great trunk. They also occasionally originate from
the gluteal artery. These vessels enter the anterior foramina
of the OS sacrum, to be distributed on the cauda equina and

296 SMALLER BRANCHES OF THE INTERNAL ILIAC.

the membranes which invest it. Some of their ramifications
anastomose with branches of the sacra media and other con-
tiguous arteries.

On the anterior side of the internal iliac, near the origin of
the above mentioned vessels, a ligament, which was originally
the umbilical artery, goes off to the side of the bladder, and
continues from thence to the umbilicus. Sometimes it con-
tinues previous for a short distance, and then small branches
pass from it to the bladder.

In the female it also sends small branches to the uterus and
vagina.

In addition to these Vesical Arteries derived from the umbi-
licals, there are other branches distributed to the bladder, which
arise very differently, in different subjects, from branches
which are soon to be described, as the hemorrhoidal, pudic, &c.

From the anterior side of the internal iliac, or from one of
its great branches, an artery arises which passes out of the
pelvis through the aperture in the margin of the ligamentous
membrane which closes the foramen thyroideum of the os
innominatum ; this is called the

Obturator Artery.

This vessel, while it is in the pelvis, often sends small branches
to the bladder and its appendages, and to the obturator internus
muscle. After it passes out of the pelvis, it divides into
branches ; some of which are spent on the obturator externus,
and the contiguous muscles, and others go to the hip joint.
— One branch of the artery called internal, is distributed in
the adductor, gracilis and pectineus muscles which are placed
on the inner side oC the thigh. — The origin of this artery is
variable. Most commonly it arises from the internal iliac, but
often from the ischiatic, and sometimes from the gluteal. In
some instances, it originates in a way that is particularly inte-
resting, when the operation for crural hernia is to be performed,
viz. from the epigastric artery, soon to be described .' for in
this case the obturator artery sometimes nearly surrounds the

LARGER BRANCHES OF THE INTERNAL ILIAC. 297

neck of the hernial sac* — According to J. Cloquet, the artery
arises from the epigastric in one case out of four. But, judging
from my own dissections, this proportion is too great. Occa-
sionally, also, the epigastric is given off from the trunk of the
obturator. —

A small artery passes from the internal iliac or one of its
branches, to the rectum, which is called the

Middle HcBinorrhoidal,

From its situation between the branches which are sent to
that intestine from the inferior mesenteric, and those which go
to it from the pudic. This artery is spent upon that part of
the rectum which is above and in contact with the sphincter.
It sends branches to the prostate and vesiculae seminales, in
males, and to the vagina and bladder in females.

In females there is a peculiar artery.

The Uterine,

Which originates either from the internal iliac, near the origin
of the ischiatic, or from one of its branches. It passes between
the lam.ina of the broad ligaments to the cervix uteri, and pene-
trates the texture of that organ. The size of this vessel varies
with the varying size of the uterus.

The Gluteal or Posterior Iliac Artery,

One of the two great branches of the internal iliac, proceeds
exteriorly through the sciatic notch above the pyriform mus-
cle, very near the edge of the bone. On the outside of the
ilium it generally divides into two branches, one of which
ramifies between the gluteus medius and minimus, and the
other between the medius and maximus. It is principally
spent upon these muscles, and sends branches to the contiguous
parts.

* See Astley Cooper's great work on Hernia, vol. i.

There is reason to belie\^e that this position of the artery occurs more fre-
quently than has been supposed.

298 PUDIC ARTERY.

The Ischiatic Artery,

The other great branch of the internal iliac, passes through
the sciatic notch below the pyriform muscle, and proceeds
downwards, between the great trochanter of the os femoris and
the tuberosity of the ischium, under the gluteus maximus
muscle. Soon after its origin, it commonly sends off a conside-
rable branch, the Arteria Pudica, which also passes downwards:
it then continues its course as above mentioned, and its princi-
pal branches are distributed to the gluteus maximus and the
muscles of the upper and back part of the thigh, while its
smaller branches go to the os sacrum and coccyx, and the con-
tiguous small muscles.

— An internal branch called the coccygeal, pierces the great
sacro-sciatic ligament, and supplies the levator ani and coccygeus
muscles.

— Another passes down the back part of the thigh in company
with the sciatic nerve to which it sends branches. —

The Pudica Interna,

As has been just mentioned, is usually a branch of the ischi-
atic artery, but sometimes originates immediately from the
internal iliac. It proceeds downwards and inwards, diverging
from the ischiatic, and passing between the two sacro-sciatic
ligaments to the interior side of the tuberosity of the ischium,
whence it continues on the inside of the crura of the os ischium
and pubis until it approaches the symphysis, when it generally
divides Into three branches, which are spent upon the organs
of generation, from which circumstance the name of this artery
is derived.

— Throughout the greater part of this course it lies upon the
obturator internus muscle and is closely bound down by the
obturator fascia between which and the muscle it is placed.
— The three terminal branches are the artery of the bulb of the
urethra (^arteria hulhi) the artery of the corpus cavernosum
{arteria corporis cavernosi) and the artery to the back of the
penis (arteria dorsalis penis.) —

EXTERNAL ILIAC. 299

One or more branches from it also pass to the lower part of
the rectum and sphincter ani, and are called the Loiver Hcemorr-
hoidal Arteries.

In its course, it sends off many small branches to the con-
tiguous parts ; one of which, called the Perineal (transversa
perinei) leaves it near the transversus perinei, and passes
between that muscle and the skin, and between the bulb of the
urethra and the crus of the penis, to the scrotum.

When the Pudic has arrived near the bulb of the urethra,
it sends a branch into it, (arteria bulhi) which is continued
into the corpus spongiosum urethras, and ramifies there
minutely.

At the symphysis of the pubis it sends off a second branch,
which passes to the back of each crus, and, proceeding
along it, parallel to its fellow, terminates in the glans penis : in
this course it sends branches to the elastic coat, to the integu-
ments, and to the prepuce. This vessel is called the Arteria
Dorsalis.

The main trunk of the pudic artery then penetrates the
corpus cavernosum, and proceeds through it in a straight direc-
tion. Its ramifications appear to be distributed through the
internal structure of the corpus cavernosum, and some of them
extend through the septum to the other side, while others pass
to the corpus spongiosum urethrse.

— The pndic artery sometimes though rarely takes a different
course from the one here described. Instead of coming out at
the sciatic notch, it passes directly forward by the side of the
bladder to the side of the prostate gland — and gets to its proper
destination — the corpus cavernosum and dorsum penis, below the
arch of the pubis. In such case of anomaly it is liable to be
cut as it crosses the prostate in the lateral operation for stone. —

The External Iliac,

The great artery of the lower extremity, appears soon after
birth, like a continuation of the primitive iliac, and proceeds
along the brim of the pelvis behind the peritoneum, to Poupart's'
ligament, or the crural arch, under which it passes.

300 EPIGASTRIC ARTERY. CIRCUMFLEX ARTERY.

The psoas muscle is at first in contact with it on the outside,
and the internal iliac vein on the inside. As it passes under
Pou part's ligament, it is immediately anterior to the psoas and
iliacus interniis muscles, where they are united, and the crural
nerve is exterior to it. Before it arrives at the lower edge of
Poupart's ligament, it sends off

The Epigastric Artery,

Which arises on its internal side, and proceeds downwards
and inwards about half an inch ; then it turns upwards and
inwards, and continues in that direction for a small distance,
after which its course is less oblique. It passes between the
peritoneum and the abdominal muscles, at the inner side of the
internal abdominal ring, behind the spermatic cord, and the
round ligaments in females.

It generally changes its oblique direction after passing about
two inches, and then proceeds in contact with the rectus and
very near its external edge; its ramifications are expended upon
the anterior parietes of the abdomen. And after it has arrived
as high as the umbilicus, it commonly divides into branches
which often inosculate with the ramifications of the internal
mammary.*

— The epigastric artery as before observed occasionally comes
off from the obturator ; but has then the same ultimate destina-
tion, as when it has its usual origin. —

An artery which is rather smaller than the epigastric, arises
nearly opposite to it, but rather lower, from the external side of
the external iliac. It is called

The Circumflex Artery of the Os Ilium,

And proceeds upwards and outwards to the upper margin of
the OS ilium, along which it continues very near to the spine.
It is distributed principally to the abdominal muscle, to the
iliacus internus and the psoas, and the parts contiguous.

* Several respectable surgeons have been taught by experience, that when
the abdomen is distended by ascites, the position of the epigastric artery is so
much altered, that it will sometimes be found in the middle of the oblique line,
which extends from the umbilicus to the superior anterior spine of the ilium.

FEMORAL ARTERY. EXTERNAL PUDICS. 301

The artery of the lower extremity, after passing under Pou-
part's ligament, takes the name of

Femoral Artery,

And proceeds downwards in a direction so spiral, that
although it is in front at the upper part of the thigh, it is
completely behind at the lower part. It sends branches to the
muscles of the thigh, as the aorta does to the viscera of the
abdomen, viz. by a few large vessels which extend and ramify
to a great distance among them.

The situation of the adductor muscles, and their attachment
to the OS femoris, is such, that the artery in this course must
necessarily perforate their common tendon, which it does at the
distance of one-third of the length of the bone from its lower
end. The aperture in this tendon corresponds precisely with
the general course of the artery ; and before the artery enters
this perforation, it is on the internal side of the bone; after it
has passed the perforation, it is in the posterior side of it. After
passing through the tendon of the adductors, it is denominated
the Popliteal Artery, and it retains this name until it divides.

It then proceeds downwards, being very near the bone, and
between the tendons of the flexors of the leg, covered by the
great nerve of the lower extremity, and very often, also, by the
vein. After crossing the articulation of the knee, when it is
between the heads of the gastrocnemus muscle, at the lower edge
of the popliteus muscle, it divides into the anterior tibial and
the common trunk of the peroneal and posterior tibial arteries.

The Femoral artery, soon after emerging from Poupart's liga-
ment, sends off very small branches to the inguinal glands, and
other contiguous parts. — One of these is, the superficial circum-
jiexa ilii, which pierces the fascia lata, and runs obliquely out-
wards toward the crest of the ilium. — Another is called, the
superficial epigastric, or arteria ad cutem abdominis of Haller.
This likewise pierces the fascia lata, and ascends between the
two layers of the superficial fascia obliquely upwards towards
the umbilicus. It is commonly cut in the operation for inguinal
hernia. — It also sends off the
VOL. II. 26

d

302 CIRCUMFLEX ARTERIES.

External Pudics,

Which are two or three small arteries that are generally
spent upon the scrotum in males, and the Labia Pudendi in
iemales.

About two inches below Poupart's ligament, the great branch
which has been called the muscular artery of the thigh, leaves it.
This vessel is commonly denominated

Arteria Profunda.

It arises from the back part of the trunk of the femoral, and
passes downwards and backwards, in a way that has been
compared to the separation of the internal iliac and the exter-
nal. Very soon after its origin, it sends off two branches,
which proceed, one on the internal, and the other on the
external side of the thigh, and are called the circumflexa
mterna and externa. It then passes downwards behind the
trunk of the femoral, and sometimes very near it, on the adduc-
tor muscles, and finally divides into branches, which are called
the Perforating.

The External Circumjlex

Sometimes arises from the femoral, but most commonly is a
branch of the profunda, as above stated. It passes under the
rectus and tensor vaginas femoris towards the great trochanter,
and generally divides into two branches, one of which continues
in the transverse direction, and sends branches to the upper and
back part of the thigh, and the parts contiguous to the joint ;
while the other descends in the course of the rectus femoris
muscle, and some of its ramifications extend near to the outside
of the knee.

The Internal Circumfex

Is often smaller than the other. It generally passes between
the psoas, and the pectineus muscles, and continues round the
thigh towards the lesser trochanter. Its ramifications are
expended on the upper portions of the adductor muscles and the
muscular parts contiguous to the lesser trochanter. It also sends
branches to the articulation.

POPLITEAL ARTERY. 303

The Perforating Arteries

Are two or three ramifications of the profunda, which pass
through the adductor muscles, and are expended upon the
flexor muscles on the back of the thigh. Some of the termi-
nating branches of the profunda itself are also called perforating
arteries.

The next branch of importance which is sent off by the
Femoral artery, leaves it before it enters the aperture in the
tendon of the adductors, and is called

The Anastomotic Artery.

This vessel soon inclines downwards. Its ramifications
extend into the vastus internus muscle ; some of them follow
the tendon of the adductors, and ramify about the internal
condyle.

Several small branches go off from the great artery soon
after it passes through the tendon of the adductors, which are
distributed to the contiguous muscles. Some of them are also
called

Perforating Arteries.

Among them is the principal Medullary or Nutritious Artery
of the OS femoris.

In the ham, the great artery and vein are called Popliteal.

The Popliteal Artery

Generally sends off several small branches. Two of them go
off on the inside, one above and the other below the knee ;
and two on the outside in the same manner. They are named,
from their situation, The Superior and Inferior Internal, and
The Superior and Inferior External Articulating Arteries.

The Superior Internal artery perforates the tendon of the
adductors above the internal condyle, and ramifies minutely on
the inner side of the joint.

The Superior External artery passes through the lower
portion of the biceps above the external condyle, and ramifies
minutely on the outer side of the joint. Its superior ramifica-
tions anastomose with those of the descending branch of the

J

304 POSTERIOR AND ANTERIOR TIBIAL ARTERIES.

external circumflex, while its inferior ramifications communi-
cate with those of the corresponding artery below.

The two inferior arteries originate nearly opposite lo the
middle of the joint and pass downwards.

The Inferior Internal artery passes under the internal head
of the gastrocnemius muscle, on the posterior and internal side
of the head of the tibia. Its ramifications communicate with
those of the corresponding artery above and of the tibialis
antica below. They also extend to the interior of the joint.

The Inferior External artery passes under the external head
of the gastrocnemius and the plantaris muscle, and continues
under the external lateral and capsular ligament. It is distri-
buted on the external and inferior part of the articulation, and
sends also some branches to the interior of the joint.

There is frequently an azygos vessel, called the Middle
Articular artery, which arises from the back of the popliteal,
and is distributed to the posterior part of the articulation.

The Popliteal artery after this, sends off a few small branches
to the heads of the muscles of the leg, and among them one of
considerable length, to each of the heads of the gastrocnemii.
At the under edge of the popliteus muscle, it sends off horizon-
tally a large branch, which passes directly forward between the
tibia and the fibula, above the commencement of the interosse-
ous ligament. After this, it continues to descend, nearly in the
same direction, under the soleus muscle, behind the tibia ; but
before it has proceeded farther than twelve or fifteen lines, it
sends off a branch which forms an acute angle with it ; and
approaches near the fibula, along which it descends.

The branch sent off anteriorly, is called the Anterior Tibial
artery.

The main trunk, which continues downwards, is called the
Posterior Tibial artery ;

And the branch which descends near the fibula is called the
Peroneal or Fibular artery.

• The Anterior Tibial Artery, (^Tibialis Antica.)
After its arrival on the anterior part of the leg, passes down

k.

THE PERONEAL ARTERY. 305

close to the interosseous ligament, with the tibialis amicus mus-
cle on the inside, and the extensor communis on the outside.
in the first part of its course ; and afterwards, with the extensor
pollicis pedis on the outside of it. It gradually inclines inter-
nally as it descends, so that a little above the ankle it is upon
the front part of the tibia. It proceeds thence with the tendons
of the extensor digitorum pedis, under the annular ligament,
to the upper surface of the foot, on which it continues to the
interstice of the first and second metatarsal bones, where
it descends to anastomose in the way presently to be men-
tioned.

In this course it sends off, soon after it has arrived at its
anterior situation, a recurrent branch, (recurrens tibialis) which
is distributed to the heads of the muscles and the ligaments of
the articulation, and which anastomoses with the branches of
the inferior articular arteries. It also sends ofF, on each side,
many arterial twigs to the contiguous muscles, and very fre-
quently one branch of considerable size, which passes down
near the fibula.

When it has arrived near the end of the tibia, it sends a
branch on each side, called the Internal and External Malleo-
lar. On the top of the foot, it takes the name of dorsal artery
of the foot, and among several smaller arteries, it sends off a
branch under the extensor brevis digitorum pedis, which passes
outwards and forwards, and supplies the muscles, &c., on the
upper part of the foot. This vessel is called Arteria Tarsa.
There is also another branch, called Metatarsa, which generally
arises about the middle of the foot, and passes obliquely outward
and forward, supplying the contiguous parts.

The Anterior Tibial artery having arrived at the space be-
tween the metatarsal bones of the first and second toes, bends
down to the sole of the foot, but previously sends off a branch
(dorsalis pollicis) which passes near the external edge of the
metatarsal bone of the great toe, and divides into two branches,
one of which gOes to the outside of the great toe, and the other
lo the opposite side of the toe next to it.
26*

306 PERONEAL ARTERY.

The Posterior Tibial Artery

After parting with the anterior tibial, sends off the Peroneal
or Fibular, as has been already stated, and then continues on
the back of the tibia, behind the internal ankle, to the sole of
the foot.

The Peroneal or Fibular Artery

Is not commonly so large as either of the two other arteries
of the leg, nor is it so constant. It passes down very near the
internal edge of the fibula. It is in contact, for some distance,
with the tibialis posticus muscle, and is anterior to the soleus
and the flexor pollicis longus ; it sends branches to the contigu-
ous muscles. After it has passed along two-thirds of the length
of the fibula, it frequently, but not always, divides into an ante-
rior and a posterior branch.

The Anterior Peroneal soon perforates the interosseous liga-
ment, and passing down some distance on its anterior surface,
continues to the ankle and upper surface of the foot. It gives
ramifications to all the contiguous parts in its progress, and
anastomoses with some of the small ramifications of the tibialis
antica.

The Posterior Peroneal Branch is the continuation of the
main trunk. It passes behind the external malleolus, and rami-
fies upon the external side of the foot.

The Posterior Tibial artery passes down, inclining rather
obliquely inwards, between the gastrocnemius internus, which
is posterior to it, and the tibialis posticus and flexor digitorum,
which are anterior to it. Upon the leg it gives off many small
branches, one of which, termed the Arteria Nutritia Tibia,
comes off high up,* and, after ramifying as it descends, sends a
branch to the medv\llary foramen of the tibia.

At the lower part of the leg, the Posterior Tibial is situated
rather superficially between the tendo Achillis and the tibia.
It proceeds thence behind the internal ankle in a deep situa-
tion, covered by an annular ligament, and passes between the

* This artery sometimes coHies off from the popliteal.

EXTERNAL PLANTAR ARTERY. 307

abductor muscle of the great toe and the bones of the tarsus.
It then divides into two branches — the internal and the external
plantar arteries.

TTie Internal Plantar Artery

Is commonly much smaller than the other ramification. It
passes in the direction of the internal edge of the foot, but at
some distance from it, and often lies between the aponeurosis
plantaris and the abductor pollicis. It frequently terminates by
anastomosing with one of the arteries of the great toe, and in its
course sends off several branches to the contiguous parts on each
side of it.

The External Plantar Artery

Is the continuation of the main trunk. It proceeds outwards
and forwards between the short flexor of the toes and the
flexor accessorius ; and continues afterwards between the first
of these muscles and the abductor of the little toe. At the
metatarsal bone of the little toe it begins to curve, and con-
tinues its curvature across the other metatarsal bones to the
interstice between the great toe and the one next to it, passing
between the tendons of the long extensor and the metatarsal
bones. At the interstice above mentioned, it anastomoses with
the tibialis anticus. The curvature, thus formed, is called the
Arcus Plantaris.

In this course, the External Plantar sends off several
branches to the heel and the parts of the foot, especially on the
external side ; the deep-seated parts of the foot being supplied
from the curve.

Digital branches go off from the curve, as they do in the
hand, from the curve of the ulnar. There is first a small branch
to the outside of the little toe, and then three regular branches,
which pass to the junction of the roots of the four small toes,
and divide, like the digital arteries of the hand, so as to send a
branch to the side of each toe. These digital arteries pass
between the muscle called Transversalis Pedis and the meta-

308 ARTERIES OF THE LOWER EXTREMITY.

tarsal bones. Near the heads of these bones, each of them
generally sends off two arteries that pass upwards between the
interossei muscles and the bones, and anastomose with the rami-
fications from the top of the foot.

The External Plantar, soon after sending off the third digital
artery, anastomoses with the anterior tibial, and then continues
to the junction of the root of the great toe with the one next to
it, when it divides into two branches, which go to the opposite
sides of those toes. In its course it also sends a branch to the
internal side of the great toe.

Of the Arteries of the Lower Extremity. (^See Plate ^{.facing

page 308.)

A. The Tendon of the External Oblique Muscle.

B. The Sartorius Muscle.
c. The Gracilis.

D. The Triceps Muscle.

E. The Rectus Femoris,

F. The Vastus Internus.

G. The Vastus Externus.
H. The Patella.

I. The Tilna.

K. The Head of the Fibula.

L. The Gastrocnemius Muscle.

M. The Soleus Muscle.

N. The Tibialis Anticus.

o. The Extensor Tendons of the Toes.

Arteries.

1. The Femoral Artery.

2. The Epigastric Artery.

3. The Circumflexa Ilii.

4. A Cutaneous Branch to the head of the Sartorius, the Glands, and Fat.

5. To the Inguinal Glands, and Fat ; it sends out a pudic branch also.

6. The External Pudic Artery.

7. The Profunda.

8. The Internal Circumjkx Artery.

9. The Profunda, proceeding deep into the flesh of the thigh before it
gives off the perforating branches.

The Branches of the Profunda are seen in the interstices of the Rectus and
Vastus Externus.

k.

■■/,//< /[

IT I

M

/'i /-

(j. 0./,r/u ...://,

ARTERIES OF THE LOWER EXTREMITY. 309

10. The Femoral Artery, where it lies betwixt the triceps and vastus in-
tern us muscle, before it perforates the triceps.*
11, f i^, 1.3. Articular Arteries, branches of the Popliteal Artery.

14. Th.e Anterior Tibial Artery X

15. The Reflected Branch of the Anterior Tibial Artery.

16. The Anterior Tibial Artery, continuing its course, and distributing
small branches to the surrounding muscles.

17. At this part it passes under the Annular Ligament.

18. The Internal Malleolar Artery.

19. The External Malleolar Artery.

20. The Tarsal Artery.

21. The Anterior Tibial Artery descending on the fore part of the foot.

22. The part at which the Anterior Tibial Artery sinks into the sole of the
foot, forming communications with the Plantar Arteries.

23. The last branch of the Anterior Tibial Artery, the Arteria Dorsahs
Poinds.

* Femoral Artery. This artery, near the place of its perforating the triceps,
is the subject of one of the most important surgical operations for popliteal
aneurism. In dissection it may be well to make this experiment : Place a
string so as to reach from the superior spine of the os ilii to the promi-
nent part of the inner condyle ; mark the middle of the string ; make an inci-
sion a very little towards the inside of it, in the direction of the string ; first,
you come to the sartorious muscle ; next, laying that aside, to a fascia, which
stretches from the triceps to the vastus internus ; when this is sht up you may
see the artery ; observe its shuation in regard to the vein, (he nervus longus, and
the sheath which surrounds it.

f This branch (the first perforating branch of the Popliteal Artery) is remark-
ably enlarged in Popliteal Aneurism.

% The Anterior Tibial Artery lies so under the projection of the Tibia, that it
is not often wounded ; yet it may be cut by a deep wound, and the student
should observe how it lies under the fascia and muscles.

" The Anterior Tibial Artery comes through betwixt the bones, one inch be-
low the projection of the knob of the Fibula ; we then cut by the edge of the
Peroneus Longus, and follow the partition fascia, which is betwixt this muscle
and the head of the Extensor Digitorum Commvnis. This partition carries us
deep, and we find the artery lying on the interosseous ligament."

When the artery is to be tied lower down, after slitting up the fascia, we
must cut betwixt the TUnalis Anticus, and Extensor PoUicis.

A

310 DISTRIBUTION OF THE VEINS.

CHAPTER IX.

OF THE PARTICULAR DISTRIBUTION OF THE VEINS.

Anatomists of great respectability have very difFereot
sentiments respecting the best method of describing the veins.
Some of them, in order to follow the course of the circulation,
commence with the small veins, and proceed to the large trunks
which are formed by their union. Others begin with the great
veins that empty into the heart, and proceed from them to the
small ramifications of the venous system, in a direction the
reverse of the circulation.

As the last method is the easiest for the student of anatomy,
it will be adopted here ; but it must always be kept in mind,
that the blood flows from the small veins into the larger, and
not from the latter into the former, as the mode of description
seems to imply.

The great trunk of the venous system differs considerably
from that of the arterial with respect to its connexion with the
heart ; for it communicates with that organ in such a manner,
that, when viewed from before, it appears like two vessels ; one
opening into the upper, and the other into the lower part of the
right auricle. When viewed from behind, it appears like a
continued tube, three-fourths of which are deficient anteriorly ;
and to the margin of this deficiency the right sinus or pouch of
the heart is connected.

In some preparations of the heart, where all the great vessels
connected with it are much distended by the injection, and the
pulmonary vessels are injected first, the right auricle is so much
pressed upon from behind, by the vessels which go to the right
lung, that the direction of the superior and inferior portions of

CORONARY VEINS OF THE HEART. 311

the vena cava, which thus communicate with it, is altered.
Each of them is turned obliquely forwards, so that it forms an
angle with the other. This occasions them to appear more
like distinct vessels than they otherwise would do.

The above mentioned portions of the great veins are denomi-
nated the Superior or Descending, and the Inferior or Ascend-
ing Vena Cava; as if they were perfectly distinct and uncon-
nected with each other.

The Coronary Veins,

Which are exclusively appropriated to the heart, may be
considered here, as they are not included in the general ar-
rangement of the veins.

The great vein of the heart begins at the lower part of the
right auricle, very near to the septum, which divides the two
auricles. It soon proceeds to the left in a circular direction,
surrounded with adipose matter, in the deep groove which
exists between the left auricle and the left ventricle. It con-
tinues between the auricle and ventricle, until it is immediately
over the septum, which divides the two ventricles. Here its
direction changes, and it proceeds to the apex of the heart,
where its small ramifications anastomose with others soon to
be described. In its course round the basis of the left ven-
tricle, it sends off several branches, one of which is of consider-
able size, that proceed from the basis towards the apex of the
heart, ramifying on the surface of the left ventricle.

A second vein, much less than the first, appears to proceed
from the great vessel at its commencement,* and continues on
the lower flat surface of the heart, between the two ventricles,
to the apex, accompanied by a branch of the right coronary
artery. This has been called the Middle Vein of the heart.

In addition to these there are several veins which begin at
the right auricle, and extend on the surface of the right ven-
tricle towards the apex of the heart. These have been called,
the Anterior Veins.

* It often opens into the auricle by a separate orifice.

312 SUPERIOR VENA CAVA AND ITS GREAT BRANCHES.

Of the Superior or descending Vena Cava, and the veins
which communicate with it.

This great vessel proceeds upwards from the superior and
posterior part of the right sinus or pouch of the heart ;* and a
portion of it is so involved by the pericardium, that it seems to
be included in that sac, as the heart is, in this situation. It is
somewhat anterior as well as to the right of the aorta. It
continues above the pericardium, adhering to the right lamen
of the mediastinum, and rather inclining forward. When it
is as high as the lower margin of the u[)per rib, it sends off a
very large branch, which conveys the venous blood of the left
arm and the left side of the head and neck. This large vein,
which is very important, both on account of its size and situa-
tion, proceeds in a transverse direction within the sternum,
almost in contact with, and but little below, the upper and
internal margin of that bone. Immediately behind, or within
the origin of the left sterno-mastoid muscle, it divides into the
left subclavian, which preserves a transverse course, and the
left internal jugular, which proceeds to the cavity of the cran-
ium by the foramen lacerum.

After sending off this transverse branch of the left, the
great vein continues upwards and behind the right sterno-
mastoid muscles, and there sends off, nearly at right angles,
the right subclavian vein. After it has parted with this vein,
it takes the name of Internal Jugular, and continues to the
right foramen lacerum, in the basis of the cranium. The
superior vena cava is, therefore, principally formed by the
union of the subclavians and internal jugulars from each side of
the body.

Immediately after the superior cava rises above the pericar-
dium, before it divides as above stated, it sends off, from its
posterior part, a large vein which is single, and, therefore, called

Vena Azygos.

This vessel projects backwards above the right pulmonary
artery and right branch of the trachea, and then curves down-

* See description of the heart, vol. i. page 504.

k.

VENA AZYGOS. 313

wards behind them. It proceeds down the spine to the right
of the aorta and at a small distance from it, into the abdomen,
between the crura of the diaphragm, and sometimes between
some of the portions of that nmscle, which are attached to the
dorsal vertebrae. In the abdomen it often anastomoses either
with the lumbar veins or the vena cav^a.

The azygos frequently sends off several small veins from its
curvature to the contiguous parts, and also the right Bronchial
Vein, which passes along the ramifications of the trachea into
the substance of the lungs.* In its course downwards it gives
off branches to the CESophagus, some of which are of conside-
rable size.

The Inferior Intercostal Veins originate directly or indirectly
from the azygos. In some cases there is no superior intercostal
on the right side ; and then the two or three uppermost of the
right intercostals are also derived from the azygos; and often
originate from it by a common trunk, which soon divides.
Most commonly the ten inferior intercostals on the right side
proceed directly from the azygos, and accompany the inter-
costal arteries. Their posterior branches pass into the ver-
tebral cavity, and communicate with the veins which are
there.

About the sixth or seventh rib, the vena azygos frequently
sends off a branch to the left, which descends on the left side
of the vertebrae, and sends off those left intercostal veins which
are below its origin. It passes through the diaphragm with
the aorta, or to the left of it, and anastomoses either with the
azygos itself, or in a way which is analogous to the anastomosis
of that vessel.

The Vena Azygos may be regarded as the great trunk of
the veins of the parietes of the thorax, which are thus collected,
because they could not with convenience pass singly to the vena
cava, as the arteries do to the aorta.

Soon after sending off the vena azygos, the Superior Cava
sends off the great transverse branch above mentioned. From
this it continues upwards but a short distance, when it divides,
* This bronchial vein sometimes arises from the superior cava.
VOL. II. 27

314

SUPERIOR INTERCOSTAL VEINS.

behind the right sterno-mastoid muscle, into the right subclavian
and right internal jugular.

The branches of the superior cava,
which thus intervene between the
great trunk and the subdivisions
behind the sterno-mastoid muscles,
are often called the Subclavian
Veins ; but they do not appear to be
accurately named.f For, 1st, they
are not situated under the clavicle,
and, 2dly, they are the common
trunks of the subclavians and internal
jugulars united.

There is a difference in the places
where some of the smaller veins origi-
nate on each side. The internal
mammary and the inferior thyroid,
on the right side, arise from the supe-
rior cava, or from the subclavian at
its origin. On the left side, they
arise from the subclavian.

The Superior Intercostal Veins

Are somewhat different on the
two sides. That on the right is
often the smallest and the least ex-

* The veins of the trunk and neck. 1. The superior vena cava. 2. The left
vena innominata. 3. The right vena ionominata. 4. The right subclavian
vein. 5. The internal jugular vein. 6. The external jugular. 7. The ante-
rior jugular. 8. The inferior vena cava. 9. The external iliac vein. 10. The
internal iliac vein. 11. The common iliac veins ; the small vein between these
is the vena sacra media. 12, 12. Lumbar veins. 13. The right spermatic
vein. 14. The left spermatic, opening into the left renal vein. 15. The right
renal vein. 16. The trunk of the hepatic veins. 17. The greater vena azygos,
commencing inferiorly in the lumbar veins. 18. The lesser vena azygos, also
commencing in the lumbar veins. 19. A branch of communication with the
left renal vein. 20. The termination of the lesser in the greater vena azygos.
21. The superior intercostal vein ; communicating inferiorly with the lesser
vena azygos, and terminating superiorly in the left vena innominata.
f They are now called vencB innominata. — p.

THE VERTEBRAL VEINS. 315

tensive. It commonly originates from the posterior and infe-
rior part of the subclavian opposite to the origin of the verte-
bral, and is generally distributed to the first and second inter-
costal spaces, but rarely to the third.

The Left Intercostal frequently originates near the left
internal mammary, and sometimes in common with it. It
descends behind the aorta on the left of the spine, and com-
monly sends off the six upper intercostal veins, of which the
two or three superior pass upwards from a part of the vein
which is opposite to the third dorsal vertebra. Its extent is
very difierent in different subjects. In some instances it passes
so low as to supply the seventh or eighth intercostal space.
This vein also gives off the Left Bronchial Vein, which sends
branches to the oesophagus and bronchial glands.

The Vertebral Veins

Arise from the subclavians, but sometimes they proceed
differently in different subjects : the right passing behind, and
the left before the subclavian artery of its respective side.
Each of them, however, becomes contiguous to its correspond-
ing artery. When it has arrived at the place in the transverse
processes, where the artery enters the vertebral canal, it sends
off an external branch, which passes up before, and nearly in
contact with those processes, and gives ramifications to the
contiguous muscles, and also to the cavity of the spine. These
last mentioned ramifications enter by the lateral apertures
between the transverse processes, and anastomose with the
veins and sinuses of the cavity. The branch often finally ter-
minates in the lateral sinus of the dura mater, by passing
through the foramen near the mastoid process of the temporal
bone. The Main TrunJc of the vertebral vein generally sends
off another external branch to the muscles near the basis of
the neck, and afterwards enters the canal with the vertebral
artery. While in this canal, it generally sends off two branches
through each of the lateral apertures between the vertebrae.
One of these branches passes backwards to the muscles of the
neck, and the other proceeds into the great spinal cavity, and
communicates with the venous sinuses.

316 THE INTERNAL JUGULAR.

When it has arrived at the atlas, the Vertebral vein sends
branches to the contiguous muscles of the neck. It also fre-
quently sends a branch through the posterior condyloid fora-
men of the occipital bone to the lateral sinus.

It is evident, from these circumstances, that the vertebral
vein carries a portion of blood from the sinuses of the brain
and of the spinal marrow, as well as from the muscles of the
neck, into the subclavian veins.

The veins of the head are frequently very different in differ-
ent subjects.

The Internal Jugular,

Already mentioned, is almost exclusively appropriated to
the cavity of the cranium ; and all the exterior veins of the
head are ramifications of one or more smaller vessels, which
pass up superficially on the neck, and are denominated Exter-
nal Jugulars. In some instances almost all the exterior veins
of the head are united to the internal jugular at the upper part
of the neck, and it of course conveys the blood of the exterior
as well as of the interior parts of the head. Frequently these
veins are divided between the internal and external jugulars,
but they are divided very differently in different subjects.

The Internal Jugular, however, almost always passes in the
same direction from the inside of the origin of the sterno-mas-
toid muscle to the posterior foramen lacerum of the cranium.
It is deeply seated on the external side of the common carotid
artery, and under the sterno-mastoid muscle. Between the
upper margin of the thyroid cartilage and the angle of the
lower jaw, it often sends off branches which are very different
in different subjects, but commonly pass to the anterior parts
of the neck and face: above these it generally sends another
to communicate with the external jugular. One of the branches
which often go off from the internal jugular is that which cor-
responds with the superior thyroid or laryngeal artery. This
vein, which has sometimes been called the Guttural, sends
many ramifications to the thyroid gland. The Ranular veins,
which are so conspicuous under the tongue, are also deriyed

THE EXTERNAL JUGULAR. 317

from it ; and it likewise sends branches to the larynx and
pharynx.

Before the internal jugular enters the foramen lacerum, it
suffers a partial dilatation, which is generally larger on one
side than the other.* This dilatation occupies the fossa at the
foramen lacerum. After passing through the aforesaid fora-
men, the internal jugular terminates in the lateral sinuses of
the dura mater.f These and the other sinuses within the
cavity of the cranium are important portions of the venous
system, which are interposed between the smaller branches,
spread upon the pia mater and the great trunks of the neck.
They will be described in the account of the brain. Into these
sinuses the very numerous veins of the pia mater, open, pro-
ceeding to the sinuses in a direction the reverse of that in which
the blood flows in those channels.

These veins are divided very minutely on the pia mater
before they enter the substance of the brain.

Into one of these sinuses, denominated the Cavernous, the
ophthalmic vein discharges its contents. This vein proceeds
from the anterior part of the sinus into the orbit of the eye
through the sphenoid fissure.J Its ramifications correspond
generally with those of the ophthalmic artery,<§. and some of
them pass out of the orbit to anastomose with the branches of
the facial vein.

The superficial veins of the neck are variously arranged in
different persons. There is often one considerable vein,

* When the veins of the neck are injected, it very often appears that a con-
siderable portion of the internal jugular is much larger on one side than the
other, as if it were affected with varicose distention.

It also often appears that the general arrangement of the exterior vein is
different on the two sides of the head and neck.

f It is asserted that the internal coat, or lining membrane of the internal
jugulars, is continued into the lateral sinuses, and extends throughout all the
sinuses of the dura mater ; so that the blood, during its passage through the
sinuses, does not come in contact with any membrane different from that of
the veins.

I See the account of this fissure in vol. i. p. 132.

<5> The Vasa Vorticosa of the choroides are one of the exceptions to this.
27*

318 GENERAL ACCOUNT OF THE SUBCLAVIAN.

The External Jugular,

Which is sent off by the subclavian, very near its union with
the internal jugular ; but sometimes it goes off from that vein
much nearer the shoulder. There are sometimes two external
jugulars, an anterior and posterior, nearly of equal size. More
frequently one of them is much smaller than the other. In a
majority of cases, the principal external jugular goes off near
the junction of the internal jugular and subclavian, as above
stated, and proceeds upwards towards the angle of the lower
jaw, passing between the platysma myoides and the sterno-
mastoid muscle. It often sends off, at the basis of the neck,
one or more branches to the contiguous muscles, and then
proceeds upwards. Near the angle of the jaw, it often com-
municates with the internal jugular : it then continues upwards,
covered with the parotid gland, near the temporal artery,
and finally divides into superficial and deep-seated temporal
branches.

The External Jugular, near the angle of the jaw, often
sends off the facial vein, which crosses the basis of the lower
jaw, near the facial artery, and distributes branches to the side
of the face and to the forehead. It also very often sends off,
near this place, the internal maxillary vein, which generally
ramifies in such a manner that its branches correspond with
those of the internal maxillary artery. Veins which corres-
pond to some of the other branches of the external carotid
artery, the lingual, occipital, &.c., are often sent off near this
place by the external jugular. They take the names of the
arteries to which they correspond, and commonly accompany
them.

The Subclavian Vein,

Although it originates differently on the two sides of the
neck, is situated alike on each of them. After parting with
the internal jugular, it proceeds over the first rib, under the
clavicle, and does not pass between the scaleni muscles, as is
the case with the arteries, but before the anterior scalenus
muscle. It soon joins the great artery of the arm, and pro-

GENERAL ACCOUNT OF THE GREAT VEIN OF THE ARM. 319

ceeds before or below it to the axilla. In this situation, it mves
off branches to the contiguous parts, ^'^S' 1^9.*

which correspond with those given off ^j

by the artery. In this course it also n „i 7

often gives off a large branch, called the

CepAaZic,

Which soon becomes superficial, and
proceeds downwards between the mar-
gins of the deltoid and pectoral muscles :
it continues superficial on the external
side of the biceps muscle, sending off
many cutaneous branches. Near the
external condyle of the os humeri, it
generally sends off a branch towards the
middle of the anterior part of the fore-
arm, which is called the Median Ce-
phalic, and also some other superficial
branches. It then continues over the
radius, and inclining to the back of the fore-arm, until it arrives
at the back of the hand, where it divides into branches, some of
which go to the thumb.

In the axilla, the great vein, there called

The Axillary Vein,
Generally divides into two or three branches. One, which is
commonly the largest, and appears like the continuation of the
main trunk, is called

* The veins of the fore-arm and bend of the elbow. 1. The radial vein.
2. The cephalic vein. 3. The anterior ulnar vein. 4. The posterior ulnar vein.
5. The trunk formed by their union. 6. The basilic vein, piercing the deep
fascia at 7. 9. A communicating branch between the deep veins of the fore-
arm and the upper part of the median vein. 10. The median cephalic vein.
11. The median basilic. 12. A slight convexity of the deep fascia, formed by
the brachial artery. 13. The process of fascia, derived from the tendon of the
biceps, and separating the median basilic vein from the brachial artery. 14.
The external cutaneous nerve, piercing the deep fascia, and dividing into two
branches, which pass behind the median cephalic vein. 15. The internal cuta-
neous nerve, dividing into branches, which pass in front of the median basilic
vein. 16. The intercosto-humeral cutaneous nerve. 17. The spiral cutaneous
nerve, a branch of the musculo-spiral.

320 GENERAL ACCOUNT OF THE GREAT VEIN OF THE ARM.

The Basilic Vein.

This vessel passes down, deeply seated, to the bend of the
elbow. It becomes superficial near the internal condyle, and
divides into several branches. One of these, called median
basilic, generally proceeds to join the median branch of the
cephalic, and from the union of these two branches is formed
the median vein, which passes down near the middle of the
anterior part of the fore-arm. This vein generally sends off a
branch which proceeds internally, see fig. 179, and anasto-
moses with the deep-seated radial veins of the fore-arm.
— This venous branch, which establishes a direct communica-
tion between the superficial and deep-seated veins at the bend
of the arm, is called the vena communicans, and is deserving
of particular attention on the part of the student. It is the
channel through which the blood is chiefly made to flow by
the action of the flexor muscles of the fingers, commonly put
in motion during venesection, from the deep-seated to the
superficial veins, so as to facilitate the withdrawal of blood in
that operation. It is provided with valves, which open in a
direction so as to prevent a return of blood toward the deep-
seated veins ; a direction which is different from that of any
other branch that I have yet noticed, connected with the deep-
seated system of the veins of the arm. In my own dissections
I have more frequently seen this vein open into the median
basilic, than into the median vein, as represented in fig. 179,
p. 319. The former therefore I look upon as the normal arrange-
ment. Occasionally it has opened into the median cephalic.
It passes from within outwards, through the fascia, at the outer
side of the tendon of the biceps, and between the pronator radii
teres, and supinator radii longus muscles.

— In some instances that rarer form of aneurysm at the bend
of the arm called aneurysmal varix, is produced not by a
direct communication made by an unhealed puncture from a
lancet through both coats of the median basilic vein and the
anterior wall of the artery by which the blood seems to get into
the superficial venous branch — but by one of the deep-seated

GENERAL ACCOUNT OF THE GREAT VEIN OF THE ARM. 321

brachial veins which has been opened by the same puncture,
SO as to receive the blood of the artery and transmit it exter-
nally through the ve7ia communicans into the superficial veins
at the bend of the arm, which form then an elongated pulsa-
tory tumor. Both punctures made with the lancet through
the median basilic vein, healing up in this case without forming
a communication with the artery. A patient presenting this
form of disease is now under my care. By pressing with the
finger between the place of puncture of the lancet, and the
outer end of the vena communicans which is usually below the
former, the pulsation of the veins above is arrested. This con-
stitutes one means of diagnosis of a peculiar form of aneurysm,
which sometimes gives rise to serious results, when meddled
with by the usual form of operation. —

There are frequently two other branches of the basilic vein.
One, which is small, passes down on the ulnar side of the
anterior part of the fore-arm, but does not extend to the wrist.
The other passes down on the ulna, and gradually proceeds to
the back of the hand, when it divides into several branches,
one of which is generally appropriated to the little finger.

The Axillary vein, after the Basilic leaves it, sometimes
divides into two branches, and sometimes continues undivided.
In either case it accompanies the humeral artery, and takes the
name of Humeral Vein or Veins. It sends off branches which
correspond to those of the artery, and continues to the bend of
the elbow ; here it is so divided, that two of its ramifications
accompany each of the three arteries of the fore-arm. These
ramifications sometimes communicate with each other by
anastomosing branches near the elbow, and they communicate
also with the superficial veins.

The superficial veins of the arm are so different in different subjects, that a
general description will rarely apply accurately to an individual case. It
may, however, be observed that a Cephalic vein will generally be found,
which very frequently arises from the subclavian instead of the axillary, and
commonly continues to the hand on the radial side of the arm. The super-
ficial veins, on the ulnar side of the fore-arm very frequently are branches
of a large vein which accompanies the humeral artery to the elbow, namely,
the basilic ; but the median vein, formed by branches of the cephalic and
basilic veins, is very often not to be found.

322 SITUATION OF THE INFERIOR VENA CAVA.

Of the Inferior Vena Cava and the Veins which are con-
nected with it.

This great vessel exceeds the Superior Cava in diameter. It
proceeds from the lower part of the right auricle, and very
soon perforates the diaphragm, at a small distance in front of
the spine, and rather to the right of the centre. As the peri-
cardium adheres to the diaphragm at this place, the vessel
appears to leave it abruptly. Immediately after leaving the
diaphragm, it proceeds along a groove in the posterior edge of
the liver, formed by the great lobe and the lobulus Spigelii.*
After leaving the liver it continues downwards, inclining back-
wards and to the left, and is soon in contact with the aorta,
which is on the left of it. It accompanies the aorta to its great
bifurcation, and divides in the same manner. It sends off,
during this course, branches to the diaphragm, liver, right
renal glands, the kidneys, and the testicles ; and also the lum-
bar and middle sacral veins.

The Inferior Phrenic Veins

Are thus denominated to distinguish them from other veins,
which are derived from the internal mammary, &;c. They
generally accompany the phrenic arteries, and are distributed
in the same manner.

The Hepatic Veins

Pass off from the vena cava, nearly at right angles, into the
substance of the liver, while this vein is in the groove of that
viscus, and before it has proceeded more than eight or ten lines
from the heart.

They arise from the anterior part of the vena cava, and are
generally three in number. Sometimes there are two only,
but then one of them divides immediately after it enters the
substance of the gland.

The distribution of these vessels in the liver has been
detailed in the account of that organ, and therefore need not

* Sometimes it is completely surrounded by the liver.

Ik.

VENA PORTARUM.

323

be stated here ; but the veins which unite to form the vena por-
tarum, and the trunk of that great vein also, before it is con-
nected with the liver, may be regarded as a portion of the regu-
lar venous system, and ought now to be considered.

Fig. 180.*

The Vena Poriarum

Passes downwards from the great sinus of the liver behind
the pancreas, and inclining to the left. In this course it sends

* The portal vein. 1. The inferior mesenteric vein ; it is traced by means
of dotted lines behind the pancreas (2) to terminate in the splenic vein (3).
4. The spleen. 5. Gastric veins, opening into the splenic vein. 6. The supe-
rior mesenteric vein, 7. The descending portion of the duodenum. 8. Its
transverse portion, which is crossed by the superior mesenieric vein and by a
part of the trunk of the superior mesenteric artery. 9. The portal vein. 10.
The hepatic artery. 11. The ductus communis choledochus. 12. The division
of the duct and vessels at the transverse fissure of the liver. 13. The cystic
duct leading to the gall-bladder,

324 THE SPLENIC VEIN.

branches to the gall-bladder, the stomach and pylorus, and the
duodenum. At the upper and posterior edge of the pancreas,
it sends off a very large branch to the spleen, which passes, with
slight meanders, along a groove in the pancreas.

The Splenic Vein

Often sends off the Inferior Mesenteric vein, which proceeds
downwards between the aorta and the left portion of the colon.
It also sends off some of the coronary veins and the left gastro-
epiploic vein to the stomach ; many small branches to the pan-
creas ; and, finally, either from the main trunk or its branches,
before they enter the spleen, the venae breves, which pass to the
great extremity of the stomach. Before it enters the spleen, it
forms several ramifications, which accompany the branches of
the splenic artery.

After sending off the splenic, the Ve7ia Portarum takes the
name of

The Superior Mesenteric Vein,

Which is larger than the splenic and passes from behind the
pancreas, before the transverse portion of the duodenum, into
the mesentery ; where it accompanies the superior mesenteric
artery.

It is evident that the above described portion of the vena
portarum simply performs the functions of a great vein ; but
when it takes on the arrangements for entering the liver, it no
longer acts like a vein, but an artery.

The lower portion of the trunk of this vein and its ramifica-
tions is denominated Vena Porta. Ventralis. The part which
ramifies in the liver. Vena Porta Hepatica.

The Capsular Veins

Are small vessels, one on each side. That on the right passes
from the vena cava to the right glandula renalis. That on the
left arises from the left emulgent vein.

EMULGENT VEINS. SPERMATIC VEINS. 325

The Emulgent, or Renal Veins,

Are very large vessels, and, like the arteries, go off nearly
at right-angles, one to each kidney.

The right emulgent vein is not so long as the left, and it is
rather anterior to its corresponding artery. The left emulgent,
in its course to the kidney, crosses the aorta, and is anterior
to it.

These veins pass to the sinus of each kidney, and ramify
before they enter it. The ramifications follow those of the
arteries.

The Spermatic Veins

Arise one on each side ; the right from the vena cava, and the
left from the emulgent vein. They proceed downwards behind
the peritoneum, and on the psoas muscle generally divide into
many branches, which communicate with each other as they
progress downwards, and form a plexus denominated Corpus
Pampiniforme. These branches proceed in the spermatic cord
to the back of the testis. The principal part enters the body of
that gland ; but some of the branches go to the epididymis. In
females the spermatic vein, like the artery, passes to the ovary,
the uterus and its appendages.

The Lumbar Veins

Correspond to the arteries of the same name. They arise
from the posterior and lateral parts of the inferior cava, and
those on the left side pass under the aorta.

The Middle Sacral Vein

Resembles the artery of the same name in its origin and
distribution.

The Inferior Vena Cava accompanies the aorta to the space
between the fourth and fifth lumbar vertebrae, and there it also
divides into the two

VOL. II. 28

326 INTERNAL ILIAC. VESICAL VEINS.

Primitive Iliac Veins.

The left vein crosses behind the artery of the right side, and
rather behind the left primitive iliac artery, which it accompa-
nies until they are opposite to the junction of the sacrum and
ilium, when it divides again, like the artery, into the internal and
external iliac veins.

The Internal Iliac, or Hypogastric Vein

Descends into the pelvis behind the artery, which it accom-
panies. Its ramifications correspond in general with those of
the artery, and, therefore, need not be particularly described.

The Vena Vesicates

Have such peculiarities that their ramifications require
particular attention. They arise from the hypogastric, very
near the origin of the obturator, and are large, as well as
numerous.

They are somewhat different in the two sexes. In men they
form a remarkable plexus on the lateral and inferior portions
of the bladder, and on the vesiculae seminales. This plexus
extends more or less to the prostate ; from it a number of
veins proceed to the symphysis of the os pubis, which com-
municate in their course with the pudic vein. From thence
arises the great vein of the penis, which proceeds in the
groove between the corpora cavernosa, and terminates in the
glans penis. This vein often divides, near the root of the penis,
into two : one of which is in the groove, and the other more
superficial.* i

In females, the venffi vesicales form a considerable plexus on
each side of the bladder and vagina. Many veins pass from
these to the upper portions of the bladder and the contiguous
parts, and form plexuses. The clitoris has a dorsal vein like
the penis, and it originates in a manner analogous to the dorsal
vein of the male.

* The pudic veins accompany the arteries of that name. They communi-
cate with the plexus, as above mentioned, and continue into the penis.

BRANCHES OF THE EXTERNAL ILIAC VEIN. 327

The External Iliac Vein.

The great trunk of the veins of the lower extremity proceeds
on the inside of the artery, under the crural arch or Poupart's
ligament. Before it passes from under the arch, it sends off
two branches, which answer to the circumflex artery of the
ilium and to the epigastric artery.

The Circumjlex Vein.

Arises from the external side of the iliac vein, and passes
towards the anterior end of the spine of the ilium. It divides
into branches, which accompany those of the artery of the
same name.

The Epigastric Vein

Arises from the external iliac, and accompanies the epigas-
tric artery. After passing a small distance inward and down^
ward, it turns up on the inside of the abdominal muscles. In
the first part of its course it sends off some small branches to
the spermatic cord.

After passing beyond Poupart's ligament, the name of the
great vessel is changed from external iliac to

Femoral Vein.

It proceeds downwards at first on the inside of the femoral
artery, but gradually changes its relative situation, so that, in
the thigh and in the ham, it is behind or on the outside of that
vessel.

At a short distance below Poupart's ligament, after giving
off some small branches to the external organs of generation,
and to the glands of the groin, it sends off, on the internal side
of the thigh, a very large vein, which is called the

Saphena Major.

This vein immediately becomes superficial, and passes down
on the internal side of the thigh, somewhat anteriorly ; giving
off some small branches to the contiguous parts soon after it
originates ; and many superficial veins afterwards. It con-

328 INSTANCES OF PECULIAR ARRANGEMENT OF THE VEINS.

tinues along the inside of the knee and leg to the internal ankle,
the anterior part of which it passes over. It then proceeds
along the internal part of the upper surface of the foot to the
middle, when it curves towards the external edge, and joins
the lesser saphena. On the leg and foot, it also sends off many-
branches, which anastomose with each other, and with those
of the aforesaid vein.

The femoral vein, after parting with the saphena, soon
sends off the vena profunda, and the circumflexae also, when
they do not arise from the profunda. These veins are gen-
erally larger than the arteries to which they correspond, and
their branches are more numerous ; but they observe the same
course.

The great vein accompanies the artery down the thigh, and
through the perforation in the adductor magnus; but it changes
its relative position, so that it is placed behind or on the exte-
rior side of the artery, at the lower part of the thigh. It is very
often behind it in the ham, where, like the artery, it takes the
uRme of popliteal. In the ham it sends off another superficial
vein, which seems very analogous to the basilar vein of the
arm. This is called

The Lesser or External Saphena.

It proceeds from the ham over the external head of the
gastrocnemius, and down the outside of the leg, sending off
many branches in its course. It passes behind the external
ankle, and near the exterior edge of the upper surface of the
foot, about the middle of which it inclines towards the great
saphena, and forms with it the anastomosis already mentioned. '

The popliteal vein, after passing across the articulation,
ramifies like the artery, but sends two veins, which accompany
each of the three arteries of the leg.

In a few instances, some of the larger veins have been found
to be arranged in a manner very different from that which is
commonly observed.

PULMONARY VESSELS. 329

One case of this kind has ah-eady been mentioned in the
account of the liver,* where the Vena Portarum terminated in
the Vena Cava, below the liver, without entering into it.

Another very remarkable instance of peculiar arrangement is
to be seen in a preparation now in the University of Pennsyl-
vania, in which the Inferior Cava, instead of opening into the
lower part of the right auricle, passes behind it, in the tract of
the Vena Azygos, and opens into the Superior Cava, in the
place where the Vena Azygos usually communicates with that
vessel, receiving the Intercostal Veins in its course.

In this preparation, the Hepatic Veins communicate directly
with the right auricle, at its lower part ; the middle and left
hepatic veins forming one trunk before they enter, and the
right vein passing in singly.f

Of the Pulmonary Arteries and Veins, see Plate I. page 241.

Those portions of the Pulmonary artery and veins which are
distinct from the lungs may be described very briefly.

It has been already observed, that the pulmonary artery
arises from the left and most anterior part of the basis of the
right ventricle, and proceeds thence obliquely backwards,
inclining gradually to the left side for about eighteen or twenty
lines, when it divides into twe branches, which pass to the two
lungs. This course places it under the curve of the aorta : for
that great vessel passes over the right branch of the pulmonary
artery, and the right side of the main trunk of it, in such a

* See note to p. 97, of this volume.

t The foregoing preparation was made by the present editor in 1814, since
which two other anomalous cases have occurred to him.

1819. Case 1st. The ascending cava passed into the thorax on the left side
of the spine, and getting as far as its upper part, was joined there by the trunk
of the internal jugular and subclavian of the left side. It there passed across
the vessels of the arch of the aorta and joined with the descending cava. The
vessels of the liver entered the heart at the usual place, in the lower part of the
right auricle.

1820. Case 2d. The trunk formed by the junction of the internal jugular and
subclavian of the left side, instead of taking its usual course, passed down ver-
tically, before the left branch of the pulmonary artery and before the left auri-
cle, then making a slight curve between this auricle and the diaphragm joiued
■with the ascending cava. — h.

28*

330

PULMONARY VESSELS.

manner that it proceeds downwards between the two branches
and behind the angle formed by their bifurcation. From this
place of bifurcation a short hgament proceeds to the lowejr part
of the curve of the aorta, which is almost in contact with it.

Fis. 181.*

This ligament was originally the canal that formed the com-
munication between the pulmonary artery and the aorta of the
foetus. Each of the great branches of the pulmonary artery
takes a direction backwards, and to its respective side. It soon
joins the corresponding branch of the trachea and the two pul-
monary veins, being anterior to the branch of the trachea, and

* Fig. 181. — a, Left ventricle, b, Right ventricle, c, Right auricle. The
left auricle is seen above the left ventricle of the same side, d, Vena cava in-
ferior, e, Subclavian and jugular veins ; those of the left side unite to form
the vena transversa ; those of the right, to form the vena innominata ; the
junction of these larger trunks, constitute the vena cava superior or descen-
dens. /, Left carotid, g, Left subclavian artery, arising from the arch of the
aorta, h, Descending aorta, i. k, Right subclavian, and right carotid, given
off from the arleria innominata, which is seen arising from the arch of the
aorta. I, Pulmonary artery, dividing into two branches, one for each lung —
the left passing in front of the descending aorta, the right behind the aorta,
where it begins to form the curve, m, Vena cava superior, n, Aorta, o, Left
pulmonary veins, entering auricle of same side. The right pulmonary veins,
are seen on the opposite side, p, p, Lungs, t, Trachea. —

PULMONARY VESSELS. 331

above the pulmonary veins. It is also invested, in common
with them, by that portion of the pleura which forms the
mediastinum, and thus enters into the composition of the root
of the lungs.

The Pulmonary Veins are four in number — two on each
side. In conformity to the mode of description which we have
adopted, it may be said that they arise from the sides of the
Left Auricle, and proceed nearly in a transverse direction, two
of them to each lung ; where they accompany the branches of
the artery and of the trachea, being invested by the mediasti-
num, in common with these branches. It has been observed
that they differ from veins in general, by preserving a diameter
nearly similar to that of the arteries which they accompany.

PART IX.

GENERAL ANATOMY OF THE ABSORBENT SYSTEM.

The absorbent vessels are small transparent tubes, of a deli-
cate structure, which exist in considerable numbers, in almost
every part of the body.

These tubes originate upon the surfaces of all the cavities of
the body ; and of the cellular membrane, in all the various parts
into which it penetrates ; upon the internal surface of the
stomach and the intestines; and probably upon the skin.*

— The Absorbent System is frequently described under the
name of the lymphatic ; but this latter term is not so appro-
priate as the former, as a generic name, since it applies only to
that large portion of the system whose office it is to take up the
serous fluids and such effete substances as are found in the midst
of the organs exterior to the cavities of the sanguineous capilla-
ries ; whilst another portion called the lacteals, originate from
the villous surface of the intestinal canal, for the purpose of
taking up and transporting the product of digestion under the
form of chyle. Both the lacteals and proper lymphatics, how-
ever, may be appropriately described under the name of absorb-
ents, as they are precisely similar in respect to structure, unite
together so as to form common trunks, and discharge their con-
tents by a common orifice into the venous system.
— The existence of the absorbent system was unknown to the
ancients : for although Herophilus and Erasistratus discovered
parts of it in their dissections of large animals at Alexandria
in Egypt, they were perfectly unconscious of the peculiar func-
tions it performed in the economy ; and so little worthy of

* See vol. i. p. 423.

DISCOVERY OF ABSORBENTS. 333

attention was their discovery deemed, that Galen and his
followers, down to the middle of the sixteenth century,
believed that the whole function of absorption, even that of the
nutritive materials, was performed by the veins. In 1656,
Eustachius observed the thoracic duct in the horse, which he
believed to be a vein, and named vejia alba thoracis. The
chyliferous vessels were first discovered in 1622, by Gaspard
Aselli, Professor of Anatomy at Pavia, while making the dis-
section of a living dog in the presence of some friends, and
were seen for the first time in man by Gassendi, in 1628. In
1649, Jean Pecquet observed anew the thoracic duct, while
dissecting a living dog, showed it to be the common termination
of the chyliferous vessels, and was the first to suggest that these
formed a distinct vascular system.

— Up to this time, the lacteals and thoracic duct, only had been
the subject of observation, and the existence of the general
lymphatic system had not even been suspected. The honor of
having discovered the general lymphatics, has been warmly
contested by three men, Olaus Rudbeck, a young Swedish
anatomist, Thomas Bartholine, a Dane, and George JolyfF, an
Englishman. It is now generally admitted to belong to Rud-
beck, who observed the lymphatics in 1651, and in the following
year, demonstrated them publicly before the young Queen,
Christina, of Sweden. Since that time this interesting depart-
ment of anatomy has had many zealous and successful cultiva-
tors, among whom may particularly be mentioned, Ruysch,
Meckel, Lieberkuhn, the Hunters, Hewson, Monro, Cruikshank,
Sheldon, Soemmering, Schreger, Werner, Haase, and Mascagni ;
and more recently, especially in the field of comparative ana-
tomy, Fohman, Lauth, Lippi, Rossi, Panissa, Arnold, Miiller
and Breschet.

Comparison hettveen the Absorbent Vessels and the Veins.

— The absorbent vessels like the veins, constitute an immense
system, which originate as minute tubes in all portions of the
body, run from the circumference to the centre, and converge
into two or more canals of considerable size, which open into

334 COMPARISON BETWEEN THE ABSORBENTS AND VEINS.

large venous trunks. Like the veins, also, the absorbents are
divided, into two portions or couches ; a superficial set of ves-
sels which are extensively spread immediately under the skin,
and accompany in general the superficial veins of the limbs;
and into a deep-seated or profound, which accompany the deep-
seated arteries and veins. Like the veins, tgo, the absorbent
vessels are provided abundantly with valves.
— Here the analogy ceases between the two systems of vessels.
The absorbents differ from the veins, in having their course
interrupted from time to time, by the lymphatic glands; by the
mode in which they run, not uniting successively into branches
and into trunks like the veins, but each running as it were an
independent course from their origin to near their termination,
and not enlarging much in diameter, though they anastomose
frequently with each other. The fluid which circulates in the
veins, is yet, though in a diminished degree, under the influence
of the heart (vis a tergo) ; the fluid of the absorbent vessels,
appears to be exclusively under the influence of the walls of the
vessels themselves. The origin of the veins have been clearly
shown by the microscope, to be from the arteries through the
intervention of the capillary vessels ; whilst the origin of the
absorbents though yet involved in much obscurity, on account of
their tenuity and the transparency of the fluids which they
carry, is believed to be wholly different. —

The absorbents which originate in the Lower Extremities
and the Cavity of the Abdomen, unite and form a large trunk
called the Thoracic Duct, which proceeds through the thorax,
and terminates in the left Subclavian Vein, at its junction
with the Internal Jugular. Those of the Left Upper Extre-
mity, the Left Side of the Head, and the contiguous parts,
form a trunk which terminates in the same place. While the
remaining absorbents, or those of the Right Upper Extremity
and the Right Side of the Head, ^c, also form a trunk which
terminates in the corresponding part of the Right Subclavian
Vein.

The absorbent vessels of middle size, which arise from
the union of the small vessels, and unite to form the larger, in

STRUCTURE OF THE ABSORBENT VESSELS. 335

their progress to these large vessels, pass through certain bodies
which have been denominated Conglobate Glands, and may
be considered as appendages of the absorbent system.

The absorbent vessels are composed of two coats, which are
thin, but dense and firm, and also elastic* The coats of the
thoracic duct may be separated from each other. The internal
surface of the exterior coat is fibrous. The internal coat is a
delicate but strong membrane. There is great reason to
believe that the above mentioned fibres are muscular, or at
least contractile ; for the absorbent vessels have been observed,
by Haller, to contract upon the application of strong sulphuric
acid. They have also been observed to propel their contents
with considerable rapidity, by their own contraction, inde-
pendent of pressure, or of motion communicated by any other
body.

Blood-vessels are sometimes observable in the coats of the
larger absorbents, in injected subjects. The vascularity of
these tubes may also be inferred from the inflammation which
frequently takes place in them.

Nerves have not been traced into their texture ; but the
absorbents seem to be painful when they are inflamed, and,
therefore, it is probable that they are supplied with nerves.

The absorbent vessels are very generally supplied with
valves, which are much more numerous in some of them than
in others ; and are different in their number, in the same
vessels, in different subjects.

Very frequently there are several valves in the course of an
inch : sometimes a valve will not appear in the course of
several inches. In the Thoracic Duct the number of valves is
very different in different subjects. These valves are folds or
plaits of the internal membrane, and are of a semicircular form.
There are commonly two of them together originating from
opposite sides of the vessel.

The absorbents are generally somewhat dilated on the side

* Microscopical observers find in addition to these a third coat, placed on the
inner face of the second which they call the epithelial lining. — p.

336 COMMENCEMENT OF THE ABSORBENTS.

of the valve which is next to their termination, and this occa-
sions their knotted appearance when they are injected. The
object of this valvular structure seems to be the prevention of
retrograde motion of the contained fluid, in consequence of
lateral pressure.

Where the different trunks of the absorbents open into the
veins, there are one or two valves to prevent the regurgitation
of the blood into them.

The valves of course prevent the injection of the branches
of these vessels from their trunks. In some animals the valves
have sometimes been ruptured, or forced back ; and the absorb-
ents have been injected in a retrograde direction. There are
but two or three instances upon record where this has been
practicable In the Human Subject.

In consequence of the impracticability of injecting the small
branches from the larger, the absorbent vessels cannot, gene-
rally, be demonstrated at their commencement, or origin. It
is, however, to be observed, that the Lacteals, or Absorbents
of the Intestines, appear no way different from other absor-
bents ; and they have been seen distended with chyle, from
their commencement, in certain subjects who had died sud-
denly. Their origins have been described very differently by
different observers.

Mr. Cruikshank describes them as originating on the sur-
faces of the villi, by a number of very small radiated branches
with open orifices ; which branches soon unite to form a
trunk.

Lieberkuhn believed them to commence in the form of an
ampuUula. (See page 42 of this volume.)

The second Monro also believed that the absorbents began
by very small tubes, with open orifices in several species of
fish.*

It is stated by Dr. Soemmering, upon the authority of Haase,

a German anatomist, that when mercury is forced backwards in

the absorbent vessels of the foot and the heart, it has sometimes

escaped on the surfaces of those parts. The probable inference

* See his work on the Structure and Physiology of Fishes, p. 34.

lllll^

ORIGIN OF THE ABSORBENT VESSELS. 337

from these facts is, that those vessels originate by open orifices
on the surfaces of the heart and foot.

Origin of the Absorbent Vessels.

— Mascagni, who devoted the greater part of his life to the
study of the absorbent vessels, was able to demonstrate their
existence in every part of the body, with the exception of the
substance of the brain, • the spinal marrow, the eye, bones,
placenta, and umbilical cord. Within a recent period Fohman*
has succeeded in detecting them on the surface of the enceph-
alon, in the meninges, in the plexus choroides, in the pla-
centa, and in the umbilical cord ; Arnoldf has seen them upon
many of the tissues of the globe of the eye ; and Cruikshank,
Soemmering, and Bonamy,J have succeeded in tracing them
into the interior of the bones. There can, therefore, at the
present moment, be no doubt of their general distribution
throughout the body.

— On the surfaces of the different membranes of the body, these
vessels have, however, been found to be most numerous ; and
Mascagni was induced to believe that these membranes, and
especially the serous and the cellular, the latter of which forms
the web-work of the whole body, consisted of a net-work of
absorbent vessels. But he does not explain himself clearly in
regard to the point in question, viz. the mode in which these
vessels have their origin.

— The great difficulty in determining this question in man and
the superior animals, is the obstacle which the valves present
to the injection of mercury backwards and towards their roots ;
for if this could be effected, as it has been in the excretory
ducts of the glands, the anatomist, by the aid of the microscope,
would probably soon be enabled to solve the difficulty, and
especially, as there is reason to believe that the radical absorb-
ents have a diameter superior to that of the sanguineous capil-

* Memoires sur les Vaisseaux Lympbat. etc., etc. Liege, 1833 ; and, Sur les
Vaisseaux Absorb, du Placenta et du Cord Umbilicale. —

f Anatomische and Physiol. Untersuchungen uber das Auge des Menschen.
Heidelburg, 1832.—

:j: Cruvielhier Anat. Spec. T. iii.

VOL. II. 29

338 GENERAL ANATOMY OF THE ABSORBENT SYSTEM.

laries. In the absence, therefore, of all positive knowledge
upon the subject, there has been much room for speculation ;
— some believing them to originate from the arteries, — some
by open mouths or gaping orifices, — and some by a net-work,
in which the vessels, tracing them towards their origin, seem to
anastomose again and again with one another.
— The first opinion was derived from the fact first noticed by
Cowper, Cheselden, and Ferrein, that in making delicate
injections of various parts of the body, the injecting . matter,
will pass occasionally from the arteries into the lymphatics;
and Breschet* has observed the same result when an in-
jection has been pushed at the same time in several of the
smaller branches of the veins, in the direction of their roots.
The researches of Panissa,f Miiller, and others, have shown that
this takes place but sparingly in any part of the body, and in gen-
eral, only when considerable force is used, and that in some por-
tions it cannot be effected at all. So that this communication
with the blood-vessels, cannot be looked upon as evincing the com-
mon mode of origin of the absorbent vessels, which are so very
numerous ; in many instances it is probably produced by a lace-
ration of the tissues from the force of the injection, by which means
some of the injected fluid insinuates itself into a ruptured absorbent
vessel. It is even possible that a communication may be made by
forcing a passage through the pores in the parietes of the vessels,
as Fohman has suggested.

— The origin by open mouths or gaping orifices, which was main-
tained by Lieberkuhn, Cruikshank, Cruveilhier, Magendie, and
others, but only with respect to the lacteals, does not appear to
be better founded. The orifices they saw probably resulted from
a laceration of the parts, since Rudolphi, Panissa, Breschet,
Fohman, and Lauth, in experiments made expressly to deter-
mine this point, have never observed them as a normal state,
either in the injection of dead bodies, or in the microscopical
observations of the transparent parts of living animals, or in
observations like that of Cruikshank, made by Lauth and

* Le Systeme Lymph, etc., par G. Breschet. Paris, 1836 —
t Observationes Antrop. Zoolomico Fisiologiche. By Prof. Panissa, Pavia,
1833.—

1^

ORIGIN OF THE ABSORBENTS. 339

Krause, on the lacteals of a human subject, that were found
distended with chyle. (See vol. ii. p. 69.)
— The mode of origin by a mesh or net-work, is not only the
one which is best supported by the concurrent testimony of
recent observers, but appears also to have been that supported
by Mascagni. This appears to be demonstrated by the three
only modes in which the capillary absorbent vessels have been
made obvious to the eye. That of Mascagni, in which a serous
cavity was filled with a colored fluid, with which the absorb-
ents of the lining serous membrane filled themselves, and thus
became visible ; that of Lauth, which consisted in filling the
minute absorbents with mercury, and gently pushing it with
the handle of a scalpel towards their capillary extremities, in
which, as in the veins, the valves cease to exist ; and that of
Cruvielhier and others, which consists in puncturing superfi-
cially the surface of the skin, or of the mucous and serous
membranes, with the point of a mercurial injecting tube, when
the mercury will be seen gradually to dilate the orifice into a
little sac, and then to insinuate itself into the absorbent vessels.
The absorbents injected by either of these modes appear to
constitute a dense net-work or plexus of vessels, which com-
municate on the opposite side of the membrane with larger
absorbent trunks, in which valves begin to be visible. From
the injected membrane, the cuticle of the skin or the epithe-
lium of the mucous tissue may be removed by maceration,
Fig. 182.* without liberating the mercury, which

^5!^gS''^jf^::^IWWI^^^B '^ '^"^ shown to be confined not
" M^y "■« merely in the cells of the cellular

|^,^ij>ij*^v ■ tissue, but in a system of tubes.

^^«?^f%;:/,>,,,-t,:f; — Fig. 182, is a specimen of the
'fi^wil^'^f"* lymphatics of the mucous membrane
''■"';.; of the stomach, prepared in this way

:„^,,,^„„, „„,;,,;,,.,,,,,:„,,.:,.,,,:.,:,:„ by Brcschet ; and fig. 183, page 343,

of the lymphatics of the mucous surface of the glans penis, and
of the skin of the scrotum. The vessels thus injected present

* Fig. 182, is a representation of the origin of the absorbents of the stomach,
after Breschet. a, Superficial layer, b, Deep-seated layer. —

340 GENERAL ANATOMY OF THE ABSORBENT SYSTEM.

very much the appearance of a mesh of arteries and veins, for
which, no doubt, they have been sometimes mistaken.
— But the lymphatic net-work is evidently seated above the
blood-vessels, for if the latter be subsequently injected, they
never rise up so as to cover the former; and where the blood-
vessels have first been filled, the lymphatics may be subse-
quently injected above them. In the mucous membranes
provided with epithelium, the situation of the superficial
absorbent net-work is precisely the same as in the skin ; but in
mucous membranes unprovided with epithelium, or rather in
which the epithelium exists in a state of undried mucus, the
situation of the lymphatic net-work is more naked, a condition
which is eminently favorable for the accomplishment of the
function of absorption.

— Each of the villi of the mucous membranes, are now believed
to be nothing more than delicate elevations of the mucous
membranes, comprising separate loops of the sanguineous and
absorbent vessels, and probably nervous fibrils, covered by a mu-
cous pellicle. The lymphatic vessels have the same mode of
origin in the lining membrane of the cavities of the heart, as well
as on the exterior of that organ as has been proved by Lauth,
Bonamy, and Cruveilhier,* who succeeded in injecting them.
— The origin of the lymphatic vessels, from tlie midst of the
nervous, muscular, and glandular structures, is not, from the
very nature of the parts, easily susceptible of demonstration.
Nothing positive, therefore, is known in regard to it, and it is
most probable that Mascagni was right in his suggestion, that
the numerous vessels which issue from the parts, originate in
the cellular tissue which forms the woof of the organs.
— The origin of the lymphatics from the cellular tissue and
serous membrane which is but a modification of the cellular,
is certainly more general than that from any other tissue of the
body, and there is much reason to believe, that it is the princi-
pal point from which they arise — the soil in which their radi-
cles are found ; and in the different organs of the body where

* Anat. Speciale, torn. iii. —

ORIGIN OF THE ABSORBENTS. 341

lymphatics are known to originate, it is most probable, though
not yet fully demonstrated, that it is from the cellular woof
alone they take their rise. In fact, the organs in which this
tissue does not enter, are the only one from which no lym-
phatics originate, viz. the nails, horns, epidermis, ivory of the
teeth, etc. Mascagni* and Cruveilhier have observed, in
respect to the cellular tissue and the serous membranes, so
many lymphatics in their combination as to be induced to
believe that they are formed of these vessels. The microscopi
cal researches of Fohman, Arnold, and Treviranus upon this
subject, have led them nearly to the same conclusion ; the two
first believing that the cellular tissue acts the part of a sponge
to the absorbents which have their radicles in it, and that its
filaments are probably composed of very minute elementary
lymphatic vessels. Treviranu3,f in some observations upon the
lower animals, (especially in the tortoise,) by the use of a glass
of very great magnifying powers, was led to believe that the
absorbents do take their origin in the cellular tissue which
appeared to be composed of elementary cylinders, closely inter-
laced together, some twisted, some zigzag in shape, and of such
minuteness as to have a diameter only the 0.0016, to 0.0002 of
a millimetre.^ Some of these appeared to unite together, and
formed larger cylinders, which went out from the mass, united
with others of the same kind, and thus formed trunks of 0.001
to 0.0023 of a millimetre in diameter, which had the appearance
of lymphatics, and opened into the lymphatic vessels. Thus
he believes, that when ultimately analyzed, the lymphatic ves-
sels will be found to originate on all the free surfaces of the
body, in the midst of the tissues, as well as in the intestinal villi,
by elementary tubes belonging to the cellular tissue, which con-
stitutes the basis or web-work of the organs ; and which tubes
have appeared to him on the villi and free surfaces of the body,
to terminate in vesicles that seemed in some parts to be pierced
with a hole.

* Vasor. Lymph. Corp. Human. Hist, et Tconogr. Sienne, 1787. —
I Bertrage Zur Aufklaerung der Erscheinungen und Gesetze, der organits-
chen Lebens. 1836, page 100. —

I A millimetre equals the 0.039379 part of an English inch. —

29*

342 GENERAL ANATOMY OF THE ABSORBENT SYSTEM.

— Whatever the facts may hereafter be found to be, in regard
to these researches of Treviranus — for the high magnifying
powers employed would necessarily render him liable to opti-
cal illusions — we are fully justified, at the present advanced
stage of anatomical science, in considering the absorbents
as not arising either from the arteries or veins, but as separate
vessels in the meshes of the cellular tissue, which divide, unite,
re-divide, and anastomose together again and again, till they
seem to occupy the whole mass of the tissue, and convert both
the proper cellular and serous membranes, into mere spongy
absorbing surfaces.

— It would seem that absorption took place in consequence of
the permeability of this net-work structure of the tissues to the
fluids in which the absorbents are bathed, (as has been so
clearly shown by E. Edwards* to be the case in the amphibise,)
whether the fluid consists of effused serum, transmitted through
the pores of the blood-vessels and mixed up with the effete
molecules of the organs, or of ecchymosed blood, or of purulent
collections ; and that this permeation is aided by an attraction
through the walls of the vessels into their interior, called endos-
mosis by Dutrochet, where the fluid is placed under the
influence of the absorbents, and is passed onwards towards the
thoracic duct. If the assertions of Treviranus should be found
correct, it might be considered as being pumped up through a
series of the minutest capillary tubes.

— The contractility of the absorbent vessels is very evident,
and exists even for many hours after death, as may be seen
by opening an animal shortly after it has been killed. Their
force of resistance is also very considerable compared with
arteries and veins of the same diameter. — In the inferior
extremities it is considered to be to that of the arteries in
the proportion nearly of 10 to 3. — These vessels are very
elastic, and one which is almost imperceptible to the naked
eye, becomes, when fully distended with mercury, half a line
in diameter.

* De I'Influence des Agens Physiques sur la Vie, etc. —

ABSORBENT GLANDS. 343

Fig. 183 *

./•

s::^')d

— This elasticity resides in the external coat of the vessels,
which is no longer considered muscular, but as a sort of yellow

* Fig. 183 (from Breschet,) represents the inguinal region of a young in-
fant, the prepuce slit open, in order to expose the glans. a, a, Two of the
superficial inguinal lymphatic glands, b, b, Efferent lymphatic vessels, filled
with mercury, terminating in these gland.s. c, c, The same lymphatic vessels,
laid bare in the groin, to exhibit their course in the subcutaneous cellular tissue.
d, d, The same vessels penetrating the tissue of the skin, where, by their rami-
fications and anastomoses, they form a dense net-work, e, e, which, properly
speaking, constitutes their origin. This net-work is on the exterior face of the
cutis vera, and is covered only by the epidermis. /, /, Arterial branches, dis-
tended with fine colored injecting matter, in order to render it certain that the
vessels filled with mercury, are lymphatic, and not sanguineous vessels. The
termination of these vessels in the lymphatic glands, moreover, prove their
character, g, g, Prepuce slit open on its upper part, in order to show its in-
ternal face, upon which is seen a beautiful net-work of lymphatics in the cuta-
neous tissue, which is here modified so as to appear like mucous membrane.
h, h, Net-work of lymphatics in the mucous membrane covering the glans
penis. The efferent vessels of the two inguinal glands are not seen in this
figure, as they arise from the opposite side of the glands, and run deep to get
into the cavity of the abdomen, below Poupari's ligament. —

344 GENERAL ANATOrST OF THE ABSORBENT SYSTEM.

elastic tissue, somewhat like the structure of the dartos, which
allows the lymphatics to extend themselves to a great degree
without breaking, and subsequently to return upon themselves
and propel their fluid contents onwards.

— Absorbent Glands do not exist at all in reptiles and in
fishes. The first trace of them is met with in birds, where
ihey are formed merely by the absorbent vessels, interwoven
and reticulated in the form of plexus. In man, their structure
appears in fact to be the same, but the meshes are minute.
Many anatomists, as Malpighi, Cruikshank, and Werner,
believed there existed particular follicles, forming round cells
with their walls in the interior of the glands, with which the
vasa inferentia and efferentia communicated, and upon which
the blood-vessels ramified ; but nearly all modern anatomists
who have investigated this subject, adopt the opinions of
Ruysch, Hewson, Meckel, and Mascagni, that these cells are
nothing but artificial dilatations of the absorbent vessels, and
that the entire structure of a lymphatic gland consists of
convoluted lymphatic vessels, densely arranged, and anasto-
mosing freely together, over which arteries and veins ramify, the
whole being embraced by common cellular tissue, in the form of
a capsule.

— Magendie has called the attention of the profession to a fluid
peculiar to the mesenteric glands, and which was known pre-
viously to anatomists under the name of the succus •proprius.
But Lauth has shown that this fluid does not exist in the
interlobular cellular tissue, and is in fact but a part of the
common contents of the blood-vessels, and found in all the
other lymphatic glands. The absorbent glands are softer and
larger in children and young persons than in adults, and
seem to diminish in number in old men. There is nothing in
this fact, according to Lauth, that should surprise us, since
the glands are made up only of convoluted vessels, which, like
the sanguineous capillaries, become less and less active, and
are here and there obliterated in the atrophy attendant upon
extreme old age.
— It is as yet considered very doubtful, whether the absorbents

GENERAL ANATOMr OF THE ABSORBENT SYSTEM. 345

have any communication with the secreting ducts of glands.
In injecting the excretory ducts of the glands with mercury,
especially tliose of the mamma, testicle, and liver, it is very
usual to find some of it escaping into the absorbent vessels.
This, which to all appearance, would seem to prove their
direct connexion, is notwithstanding considered by many dis-
tinguished anatomists, as caused by a rupture of some part of
the glandular structure, and that the mercury finds its way
into the openings made by the laceration in the absorbent ves-
sels. But the communication between these vessels and the
excretory ducts, takes place so readily, in the injection of the
latter, and so much without the appearance of extravasation,
as to render it most probable that there exists some anasto-
mosis between them. The same degree of doubt exists in
regard to the connexion between the absorbents and small
veins. It has been chiefly alleged to exist between them in
the excretory glands of the body, and in the absorbent glands
themselves ; in all which parts, the friability of their structure
renders them liable to laceration, by the pressure from a mer-
curial column, or by ordinary minute injection thrown in with
force. Though the fact is very evident, that many of the
absorbents may be filled by injection of the ducts of the
secernent glands, and that mercury passes with extreme
facility from the lymphatics of the absorbent glands into the
veins, the weight of testimony, is certainly at present in favor
of its taking place only in consequence of a laceration of tissue.
The statements of Lippi,* in regard to the free communica-
tion, between the lymphatic vessels and veins, are now disre-
garded, in consequence of its having been shown by Fohman,
Panissa, and Breschet,f that he had mistaken in his investiga-
tions capillary veins for lymphatic vessels.

— The opinion in regard to the terminations of the absorbents,
since the alleged venous communications of Lippi have been
disproved, has now the same as that entertained formerly.

* Illust. Fisiol. e Palhol. del Sistem. Limfat. Chil. etc. Firenze, 1825. — p.
f Vide Breschet, sur la Systeme Absorbaate.

346 TERMINATION OF THE ABSORBENTS.

by Hevvson, Cruikshank, and others ; namely, that the absorb-
ent and venous systems, can be considered as connected only
by the principal lymphatic trunk, the thoracic duct, which
opens into the left subclavian vein, and by the right brachio-
cephalic, and other branches, which open into the internal
jugular and subclavian of the right side. All other communi-
cations which take place between them may be received as ex-
ceptions to the normal structure.

— The most frequent of these, are the branches between
the thoracic duct, and vena azygos. In many amphibia and
reptilia, lymphatic hearts, or dilatations of the absorbent vessels
that are capable of contracting somewhat like a heart, have
been discovered by Miiller, which assist in the circulation of the
lymphatic fluid.* Nothing analogous to them, has, however,
been discovered in man. —

The bodies connected with the absorbent vessels, which are
called Conglobate Glands, are generally of a roundish, or irre-
gular oval form, and somewhat flattened. They are of various
sizes, from two lines in diameter to more than twelve. Their
color is frequently whitish, but sometimes it is slightly
inclined to red. They are invested with a covering of cellular
membrane, which appears like a membranous coat ; and they
are connected to the contiguous parts by a loose cellular sub-
stance. When the absorbent vessels connected with these
bodies approach near to them, they divide into a number of
ramifications, most of which enter into the substance of the
gland, while some of them run over it. On the opposite side
of the gland a number of branches go out, which unite and
form trunks similar to those which entered the gland. The
vessels which enter the gland are called Vasa inferentia, and
those which go out of it Vasa efferentia.

These vessels are generally much convoluted in the sub-
stance of the glands, so that those bodies sometimes appear
like a mere convolution of absorbent vessels. There has been

* See an interesting paper on this subject by Dr. Allison of Philadelphia —
Amer. Jour. Med. Science, Aug. 1838.

OF THE CHYLE. 347

much diversity of sentiment respecting the structure of these
organs.*

The absorbent vessels, in the different parts of the body,
generally contain fluids resembling those which are found in
those parts. Mr. Hewson opened the large absorbents in
many living animals of different kinds, and found that they
contained a transparent fluid, which coagulated when exposed
to the open air.

The arrangement of these vessels resembles that of the veins
in several respects. Many of them are superficial ; but there
are also deep-seated absorbents which accompany the blood-
vessels.

Of the Chyle.

— Under this name we designate the fluid, carried by the
absorbents of the intestinal canal during digestion; in the
intervals of digestion, the trunks of the same vessels in the
mesentery are filled only with the ordinary lymph. These
vessels of the intestinal canal are called lacteals, in consequence
of their white appearance when distended with chyle. The
lymph proper, is a fluid taken up by the radicles of the general
lymphatic system, and is mixed with the chyle in the thoracic
duct. Chyle is limpid in birds, a little opaque in herbivorous
animals, and very opaque in the carnivorous, including man.
The opacity of the chyle, appears to depend upon the great
number of globules suspended in it, which appear to be found
in birds and all the mammalia, notwithstanding, the blood
globules are elliptical in birds, and flattened in man. (See vol.
ii. p. 238.) According to Miiller, the chyle globules are to be
found in the first radicles of the lacteals, as he saw them dis-
tinctly in the calf; this favors the opinion that they are not
formed in the vessels themselves, but are probably taken up in

* Mr. Abernethy states, that the mesenteric gland of the whale consists of
large spherical bags, into which a number of the lacteals open. Numerous
blood-vessels are ramified on the surfaces of these cysts ; and injection passes
from them into the cyst. He also found cells in the glands of the absorbent
vessels, in the groin and the axilla of the horse. See Philosophical Transac-
tions, for 1796, Part I.

348 OF THE CHYLE.

the state of globules during digestion, and are probably the
results of the disintegration of the alimentary matter, by the'
digestive process. The chyle has a spermatic odor, an alka-
line taste, and varies in many respects, according to the nature
of the aliment subjected to the action of the digestive organs.
According to Magendie, Tiedeman and Gmelin, the chyle from
aliments containing an abundance of fatty matter, is very white
and full of oily particles, which, when the fluid is drawn from
the vessels, float on its surface like a sort of cream : while that
formed from food possessing little or no fatty matter, is more
opaque, and exhibits but little or no creamy covering upon its
surface.

— The chyle evidently undergoes a change as it ascends in the
thoracic duct. It exhibits more and more of a rose tint in place
of its creamy color, and is more coagulable and more assimi-
lated in appearance to the blood, the nearer to the top of the
thoracic duct, that we extract it for examination during the
act of digestion. During that period the duct is filled chiefly
with the contents of the lacteal absorbents ; but little of the
general lymph of the body, being at that time transported to
the duct. When withdrawn from the duct, chyle coagulates
of itself, and the action of the air heightens greatly its rosy hue.
The coagulation takes place in this fluid, from the same causes
that it does in blood ; from the fibrine which exists in a state of
solution in the recent chyle, returning to the solid state, and
inclosing a part of the globules.

— The serum in which the coagulum floats, is a solution of
albumen, containing likewise some of the globules, and at the
same time, has floating upon its surface a layer of fatty particles.
In the lungs, where the chyle passes, mixed with the venous
blood, the final change is effected, so that the chyle can
no longer be distinguished from the sanguineous fluid. The
opaque color of the chyle in the lacteals, according to Tiede-
mann and Gmelin, is dependent not only upon the number of
the globules it contains, but in part, also, upon the minutely
divided particles of fat which are suspended in it.

THE LYMPH. 349

Of the Lymph.

'■ — The term lymph has been very loosely applied by anato-
mists and physiologists, not only to the fluids of the lymphatic
vessels, but to the serum of the blood, to the transparent fluids
of the serous cavities, and to many albuminous and fibrinous
exudations. Latterly it has been more appropriately confined
to the contents of the general lymphatic system.
— It has been collected for examination from the thoracic duct,
and from the absorbent trunks of the head, neck and upper
extremities, in many animals after several days starvation, when
no materials had been afforded for the formation of chyle ; it
has also been recently obtained by Miiller, from the human
subject, in the case of a young man in the hospital at Bonn.
This individual had received a cut on the back of the foot
which could not be made to cicatrise, and the divided absor-
bents threw out, when pressed upon, a large quantity of lymph,
which was transparent, inoderous, saline to the taste, with
alcaline properties, and which, in about ten minutes after being
collected, formed a delicate coagulum resembling a spider's
web. The lymph, when examined with the microscope,
presented many globules, much less abundant, however, and
smaller than those of the blood. During coagulation part of
these globules, were inclosed in the clot, but the greater part
were suspended in the serum.

— The coagulation was evidently produced by the solidification
of a substance previously fluid, which is considered to be fibrine,
and which, in passing to the solid state, enveloped a certain
portion of these globules, that was before free.

Comparison between Chyle and Lymph.

— Both contain globules ; but they are few in number in the
lymph, and abundant in the chyle. Both contain fibrine in
solution. The most important difference between these fluids,
consists in the fatty matter, which the chyle holds in solution,
and which does not exist in the lymph. The other constituents,
fibrine albumen, salts, etc., are much the same in both.
VOL. II. 30

350 COMPARISON BETWEEN CHYLE AND LYMPH.

— In regard to the disposition of the coloring matter which
is generally found in chyle, and sometimes even in lymph,
whether it is in a state of general solution, or attached to the
globules, as in the case of the blood, we literally know nothing
as yet. Between these two fluids there are, as may be
observed, many points of analogy with the blood. The chyle
contains new globules formed by the digestion and disintegra-
tion of the alimentary matter, and which are destined, when
they have received the last finish of assimilation in their pas-
sage through the lungs, to constitute the nuclei of the red
particles of the blood.

— The lymph also contains globules formed from the wreck of
the old materials of the body, as they exist in the molecular
state throughout the different tissues. The size of these glob-
ules, as has been shown by some observers, is about equal to
that of the nuclei of the red particles of the blood. In the
state in which they are found in the lymph, they are destined
either to be thrown out from the body, as being worn out and
worthless, or to be restored by the action of the lungs, to the
same vital condition in which they were, previous to their
having been deposited from the blood to constitute the atoms or
molecules of the different organs. —

SUPERFICIAL ABSORBENTS. 351

CHAPTER X.

OF THE ABSORBENTS OF THE LOWER EXTREMITIES, THE
ABDOMEN, AND THE THORAX.

Under this head are arranged the ramifications of all the
vessels which unite to form the Thoracic Duct.

Of the Absorbents of the Loiver Extremities.

These absorbents, like the veins, are superficial and deep-
seated. The superficial lie in the cellular membrane, very
near the skin ; and form an irregular net-work which extends
over the whole limb. They are, however, most numerous on
the internal side.

The deep-seated accompany the arteries like the veins, and
there are two at least to each artery.

The Superficial Absorbents

Have been injected from the toes so as to form a net-work,
which occupies the upper surface of the foot. They have also
been injected in a similar manner on the sole. Those on the
upper surface of the foot generally proceed upward on the
anterior and inner side of the leg; but some of them pass on
the external side of it. Those on the sole are continued on
the back of the leg, but communicate very frequently with the
anterior vessels. Some of the absorbents from the outside of
the foot and leg enter into some of the popliteal glands, soon
to be described ; but they are not numerous ; and the principal
number continues up to the glands of the groin. The absorb-
ents which originate on the surface of the thigh, as well as
those which pass over it from below, incline gradually along
the anterior and posterior surface, to the internal side of it ; on
which they proceed in great numbers, and very near to each

352 ABSORBENTS OF THE INFERIOR EXTREMITIES.

Other to the inguinal glands. Superficial absorbents proceed
also from the buttock and lower part of the back, from the
lower part of the abdomen, the perineum and the exterior of
the genital organs, to these glands.

The Deep-seated Ahsorhents
Are named from the arteries they accompany.

The Anterior Tibial Ahsorhents.

The anterior tibial artery is generally attended by one which
comes with it from the sole, and by another which commences
on the upper surface of the foot. The first mentioned absorb-
ent continues with the artery. The last passes through an
aperture in the interosseal ligament, about one-third of the
distance from the ankle to the knee, and accompanies the fibu-
lar artery, while the anterior tibial artery is joined by other
absorbents about the same place. In some instances a small
absorbent gland occurs in this course at a short distance below
the knee.

The Posterior Tibial Absorbents

Have been injected from the under side of the toes. They
accompany the ramifications on the sole of the foot ; and, after
uniting, continue with the main trunk up the leg, where they
enter the popliteal glands.

The Peroneal Absorbents arise also from the sole of the foot,
and its external side. They accompany the peroneal artery,
and terminate in the popliteal glands, which receive also the
absorbents from the knee and ham.

From these glands four or five absorbent vessels proceed
which accompany the great blood-vessels of the lower extremi-
ty ; and, proceeding with them through the aperture in the
tendon of the adductors, continue upwards until they enter
some of the glands of the groin.

The glands of the ham and groin, which are so intimately
connected with the absorbents of the lower extremity, are very
different from each other.

ABSORBENTS OF THE INFEKIOR EXTREMITIES. 353

The Popliteal Glands, or those of the Ham, are but three or
four in number, and very small in size. They are generally
deep-seated, and very near the artery.

The Inguinal Glands vary in number from eight to twelve
or more. They are superficial and deep-seated. The svper-
Jicial communicate principally with the superficial absorbents.
The lowermost of them are at some distance below Poupart's
ligament, and the uppermost are rather above it. They are
exterior to the fascia lata of the thigh. Their number is generally
six or eight, while that of the deep-seated is but three or four.
— They are placed between the lamina into which the fascia
superficialis of the thigh divides at this point. —

The superficial absorbents from below, approach very near to
each other, and enter these glands. They are commonly dis-
tributed among three or four of the lowermost ; but some of them
pass by these, and proceed to one that is higher up ; and some-
times there are absorbent vessels which pass to the abdomen
without entering into any of the glands of the groin.

The deep-seated absorbents pass into the deep-seated glands,
which, as has been already observed, are but few, and lie very
near the artery, under the fascia of the thigh. The two sets
of glands are connected with each other by many absorbent
vessels that pass between them. The vessels which finally
go out of these glands are considerably less in number than
those which enter into thetn. They proceed under Poupart's
ligament, and, in some instances, a large proportion of them
passes through three glands which lie below this ligament, and
are often so arranged, that they lie on each side of the great
femoral vessels, and above them. One very frequently is found
on the inside of the femoral vein, in the vacuity between it
and the internal part of the ligament. All the absorbents of
the lower extremity, however, do not enter these glands. Some
pass along the great vessels and enter other glands near
the margin of the pelvis. Some, also, descend a short distance
into the pelvis, and unite with vessels that are passing from the
pelvis to the plexus and the glands that surround the external
iliac.

30*

354 INGUINAL AND EXTERNAL ILIAC GLANDS.

The absorbents which proceed from the glands last mentioned,
joined to those which pass under Poupart's ligament without
entering these glands, and some which come from the pelvis, form
a large plexus, which almost surrounds the external iliac
vessels, and contains many glands.

These External Iliac Glands vary in their number from
six to ten or twelve. They lie on the side of the pelvis, in the
course of the external iliac vessels, and some of them are of
considerable size. These glands and the plexus of absorbents,
extend in the track of the iliac vessels, to the first lumbar ver-
tebra. In this course they are joined by the plexus which
comes from the pelvis ; and soon after they arrive at the
Lumbar Glands, which form a very large assemblage, that
extends from the bifurcation of the aorta to the crura of the
diaphragm.

These glands lie irregularly on the aorta, the vena cava, and
the lumbar vertebrae. Most, if not all, the absorbents above
mentioned pass through some of them ; and from the union of
these absorbents, some of the great branches, which unite to
form the thoracic duct, are derived.

In this course, from the thigh to the lumbar glands, these
absorbent vessels are joined by several others. The Superficial
Absorbents of the scrotum commonly enter into the upper
inguinal glands, and thus unite to the great body of absorbents.

The Absorbents of the Testicles, originate in the body, and
the coats of the testicle, and in the epididymis, and are remark-
ably large and numerous. They proceed along the spermatic
cord, through the abdominal ring, to the lumbar glands. These
vessels are remarkable for the little communication they have
with each other.

The Deep-seated Absorbents of the Scrotum accompany the
absorbents of the testicle to the lumbar glands ; but those which
are superficial enter the upper inguinal glands.

The Absorbents of the Penis are also deep-seated and super-
ficial. The deep-seated arise from the body of the penis, and
accompany the internal pudic artery, into the pelvis. The
superficial absorbents arise from the prepuce, and pass along

ABSORBENTS OF THE ABDOMEN AND THORAX. 355

the dorsum of the penis. (See fig. 184, p. 361.) There are
frequently several trunks which receive branches from the lower
surface of the penis in their course. At the root of the penis
they generally separate to the right and left, and pass to the
glands on the respective sides.

In females, the absorbents of the interior of the clitoris
accompany the internal pudic artery. Some, which arise about
the vagina, pass through the abdominal ring with the round
ligament ; and others proceed to the inguinal glands.

Of the Absorbents of the Abdomen and Thorax.

The Absorbents of the lower portions of the jparietes of the
Abdomen and Pelvis unite into trunks that follow the epigas-
tric, the circumflex and the iliac, as well as the lumbar and
sacral arteries, &c. They proceed to some of the glands which
are in the groin ; or to the external iliac, the hypogastric, or
some of the contiguous plexuses.

The Absorbents of the Womb are extremely numerous ; and,
in the gravid state, are very large. Those which are on the neck
and anterior part of the body accompany the spermatic vessels.

The Absorbents of the Bladder pass to small glands on its
lateral and inferior parts, and finally join the hypogastric plexus.

The Absorbents of the Rectum are of considerable size.
They pass through glands that lie upon that intestine, and unite
with the lumbar plexus.

The Absorbents of the Kidney are superficial and deep-
seated. They are very numerous, but, in a healthy state of the
parts, are discovered with difficulty. Cruikshank describes
them as they appeared, filled with blood, in consequence of
pressing upon the kidney when its veins were full of blood.
Mascagni did not inject the superficial vessels with mercury;
but describes them as they appeared when filled with colorless
size, after he had injected the blood-vessels of the organ with
the colored fluid. The deep-seated absorbents pass out of the
fissure of the kidney with the blood-vessels, and unite with the
superficial ; they proceed to the lumbar plexus, and pass into
different glands.

356 ABSORBENTS OF THE INTESTINES.

Absorbent vessels can be proved to proceed from tlie pelvis
of the kidney, and the ureters, by orifices analogous to those
above mentioned.

The Glandulce Renales are also supplied with absorbents,
which are numerous in proportion to the size of the organs.
They commonly join those of the kidney.

The Absorbents of the Intestines

Have generally been called Lacteals, froTn the white color
of the chyle which they contain : but there seems no reason for
believing that they are different in their structure and nature
from the absorbents in other parts of the body. A small num-
ber of them appear as if they formed a part of the structure of
the intestines, and originated from their external surface, as
they do in other parts of the abdomen ; while the principal part
of them are appropriated to the absorption of the contents of
the cavity of the intestines.

The first mentioned absorbents run between the muscular
and peritoneal coats, and proceed for some distance length-
ways on the intestine, wiiile the otliers proceed for some dis-
tance within the muscular coat, with the arteries ; and, after
passing through it, continue between the lamina of the mesen-
tery.

Branches of these different absorbents are frequently united
in one trunk, so as to prove that there is no essential difference
between them.

The absorbents which come from the internal surface of the
intestines commence in the villi. The manner in which they
originate ha:s been the subject of considerable inquiry, as has
been stated in the account of the intestines.*

The lacteals or absorbents of the intestines are very numer-
ous. They pass between the lamina of the mesentery to glands
which are also seated between those lamina. The number of
these glands is very considerable,! and they are various in size —

* See page 41. f They have been estimated between 130 and 150.

ABSORBENTS OF THE INTESTINES. MESENTERIC GLANDS. 351

some being very minute, and others eight or ten lines in diame-
ter. They are generally placed at a small distance from each
other, and are most numerous in that part of the mesentery
which is nearest to the spine. They are almost always at
some distance from the intestines. They appear to be precisely
like the absorbent glands in other places.

These absorbent vessels, in their course frequently divide
into branches ; which sometimes go to the same gland, some-
times to different glands, and sometimes unite with other
absorbent vessels. As they proceed, they frequently enlarge in
size. When they have arrived near the spine, they frequently
form three or four trunks, and sometimes one or two ; which
proceed in the course of the superior mesenteric artery, until
they have arrived near to the aorta. Here they either pass
into the thoracic duct, or descend and join the trunks from the
inferior extremities, to form the thoracic duct. The absorbents
of the great intestines are not equal in size to those of the small ;
but they are numerous. They enter into glands, which are
very near, and in some places in contact with the intestine ;
and are commonly very small in size. The vessels which arise
from the caecum, and the right portion, as well as the arch of
the colon, unite Vk'ith those of the small intestines; while the
vessels from the left side of the colon, and the rectum, proceed
to the lumbar glands.

The absorbents of the intestines are frequently injected with
mercury ; but the injection does not proceed to their termina-
tion with so much facility as it does in other vessels of the same
kind. They have, however, very often been seen in animals
who were killed for the purpose after eating milk ; and in several
human subjects who had died suddenly during digestion. The
description of the origin of the lacteals, quoted in page 44 of
this volume, from Mr. Cruikshank, was taken from a subject
of this kind, of which an account is given in his work on the
absorbent vessels.

It is worthy of note, that in several instances, in which the
lacteals were thus found distended with chyle, the glands in the
mesentery were also uniformly white.

358 ABSORBENTS OF THE LIVER.

The Absorbents of the Stomach

Are of considerable size, and form three divisions. The ves-
sels of the first set appear upon both sides of the stomach, and
pass throtgh a few glands on the small curvature near the
omentum minus. From these glands they proceed to others,
which are larger, and which also receive some of the deep-
seated absorbents of the liver. The vessels from these glands
pass to the thoracic duct, near the origin of the coeliac artery.
The second arise also on both sides of the stomach, and pass to
the left extremity of the great curvature to unite with the
absorbents of that side of the great omentum. They then pro-
ceed with the lymphatics of the spleen and pancreas, to the tho-
racic duct. The last set, pass off from the right extremity of
the great curvature, and unite also with absorbents from the
right portion of the omentum. They proceed to near the pylo-
rus, and go to the thoracic duct, with some of the deep-seated
absorbents of the liver.

Although the absorbents of the stomach are deep-seated, as
well as superficial, it is a general sentiment, that they do not
contain chyle in the human subject; notwithstanding chyle
has been found in the absorbents on the stomach of dogs, and
some other animals. It ought, however, to be remembered,
that Sabatier has, in some instances, seen white lines on the
stomach, which he supposed to be lacteals.

The Absorbents of the Liver

Are especially interesting, because they have been more com-
pletely injected than those of any other viscus. They are deep-
seated and supcrfcial. The superficial, it has been already
observed, admit of injection in a retrograde direction, and, there-
fore can be exhibited most minutely ramified. They commu-
nicate freely with each other, and also with the deep-seated
vessels, by their small ramifications ; so that the whole gland
has been injected from one large vessel.

The gland is so large, that the absorbents of the superior and
inferior surfaces proceed from it in different directions.

ABSORBENTS OF THE LIVER. 359

A large absorbent is generally found on the suspensory-
ligament. This is formed by the union of a great many
branches that arise both on the right and left lobes, but princi-
pally on the right. It often passes through the diaphragm at
an interstice which is anterior to the xiphoid cartilage, and
then proceeds through the glands on the anterior part of the
pericardium.

Several absorbents proceed to the lateral ligaments on each
side, and then pass through the diaphragm. Some of these
branches return again into the abdomen, and the others generally
run forwards in the course of the ribs, and join those which pass
up from the suspensory ligament. The trunk, or trunks,
formed by these vessels, either pass up between the lamina of
the mediastinum, and terminate in the upper part of the thora-
cic duct ; or they accompany the internal mammary arteries,
and terminate on the left side in the thoracic duct, and on the
right in the trunk of the absorbents of that side.

The Absorbents on the concave side of the liver are as nume-
rous as those on the convex side ; they are also very abundant
on the surface of the gall-bladder. The greatest part of them
join the deep-seated vessels.

The Deep-seated Absorbents proceed in considerable numbers
from the interior of the liver through the portas. They accom-
pany the biliary ducts and the great blood-vessels of the organ ;
and, after passing through several glands, near the vena porta-
rum, terminate in the thoracic duct, near the commencement of
the superior mesenteric artery.

Mascagni states, that the absorbents of the liver will be dis-
tended, by injecting warm water into the biliary ducts, or the
vena portarum.

He also observes, that in those preparations in which the
superficial vessels are completely injected, in the retrograde
direction, the peritoneal coat of the liver appears to be com-
posed entirely of absorbent vessels ; and to be connected
to the membrane within, by many filaments, which are also
absorbent vessels.

360 ABSORBENTS OF THE SPLEEN.

The Absorbents of the Spleen

Are composed of superficial and deep-seated vessels; but
they differ greatly from those of the liver, in this respect, that
the soperficial vessels are remarkably small in the human subject.

Mascagni, however, asserts, that when the blood-vessels
of the spleen are injected with size, colored with Vermillion, these
absorbents will be filled with colorless size.

In the spleen of the calf the superficial absorbents, are
remarkably large.

In the human subject the superficial absorbents of the spleen
proceed from the convex to the concave surface, and there com-
municate with the deep-seated absorbents, which proceed from
the interior of the organ with the blood-vessels.

These Deep-seated Absorbents are very numerous, and also
large. They accompany the splenic artery ; and in their course
pass through many glands, some of which are said to be of a
dark color. The glands lie on the splenic artery, at a short
distance from each other. Tlie absorbents of the spleen receive
the absorbents of the pancreas in their course ; they unite with
the absorbents of the stomach and the lower surface of the
liver, and pass with them to the thoracic duct.

Little has been latterly said by practical anatomists res-
pecting

The Absorbents of the Pancreas.

Mr. Cruikshank once injected them in the retrograde direc-
tion ; he found that they came out of the lobes of the pancreas
in short branches like the blood-vessels, and passed at right
angles into the absorbents of the spleen, as they accompanied
the artery in the groove of the pancreas.

The Thoracic Duct*

Or common trunk of the absorbent system, is formed by the

union of those absorbent vessels which are collected on the

lumbar vertebrae.

* First discovered by Eustachius, in the horse, 1564 ; but he considered it a
vein for the nourishment of the thoracic viscera. — h.

^

THORACIC DUCT.

361

Fig. 184.*

These vessels, as it has been already-
observed, are derived from various
sources, viz.

The lower extremities ; the lower
part of the trunk of the body ; the
organs of generation ; the intestines,
with the other viscera of the abdomen
and pelvis, except a part of the liver.
Their number is proportioned to the
extent of their origin : for, with the
numerous glands appropriated to
them, they form the largest absorbent
plexus in the body, and are spread
over a considerable portion of the
aorta and the vena cava.

The manner in which these vessels
unite to form the thoracic duct, is very
different in different subjects; but in
a majority of cases it originates imme-
diately from three vessels, two of
which are the trunks of the absorbents
of the lower extremities, and the other
is the common trunk of the lacteals
and the other absorbents of the intes-
tines.

* The course and termination of the thoracic duct. 1. The arch of the aorta.
2. The thoracic aorta. 3. The abdominal aorta ; showing its principal branches
divided near their origin. 4. The arteria innominata, dividing into the right
carotid and right subclavian arteries. 5. The left carotid. 6. The left sub-
clavian. 7. The superior cava, formed by the union of 8, the two vense inno-
minatEB ; and these by the junction 9, of the internal jugular and subclavian
vein at each side. 10. The greater vena azygos. 11. The termination of the
lesser in the greater vena azygos. 12. The receptaculum chyli ; several lym-
phatic trunks are seen opening into it. 13. The thoracic duct, dividing oppo-
site the middle of the dorsal vertebrse into two branches which soon reunite ;
the course of the duct behind the arch of the aorta and left subclavian arter}'
is shown by a dotted line. 14. The duct making its turn at the root of the neck
and receiving several lymphatic trunks previously to terminating in the poste-
rior aspect of the junction of the internal jugular and subclavian vein. 15,
The termination of the trunk of the right branchio- cephalic duct.

VOL. II. 31

362 THORACIC DUCT.

These vessels generally unite on the second or third lumbar
vertebrae ; and, in some instances, the trunk which they form
dilates considerably, soon after its commencement ; in conse-
quence of which it was formerly called the receptacle of the
chyle. At first it lies behind the aorta, but it soon inclines to
the right of it, so as to be behind the right crus of the diaphragm.
In the thorax, it appears on the front of the spine, between the
aorta and the vena azygos, and continues between these ves-
sels until it has arrived at the fourtli or third dorsal vertebra.
It then inclines to the left, and proceeds in that direction until
it emerges from the thorax, and has arisen above the left
pleura, when it continues to ascend behind the internal jugular,
nearly as high as the sixth cervical vertebra : it then turns
downward and forward, and after descending from six to ten
lines, terminates in the back part of the angle formed by the
union of the left internal jugular with the left subclavian vein.
Sometimes, after rising out of the thorax, it divides into two
branches, which unite before they terminate. Sometimes
it divides, and one of the branches terminates at the above
mentioned angle, and the other in the subclavian vein, to the
left of it.

The orifice of the thoracic duct has two valves, which
effectually prevent the passage of blood into it from the system
of the vena cava.

There are sometimes slight flexures in the course of the duct ;
but it generally inclines to the left, in the upper part of the
thorax, as above mentioned ; and is then so near the left lamen
of the mediastinum that, if it be filled with colored injection,
it can be seen through that membrane, when the left lung is
raised up and pressed to the right.

The duct sometimes varies considerably in its diameter in
different parts of its course. About the middle of the thorax
it has often been found very small. In these cases it generally
enlarges in its progress upwards, and is often three lines in
diameter, in its upper part. Many anatomists have observed
it to divide and to unite again, about the middle of the thorax.

ABSORBENTS OF THE LUNGS. 363

The Absorbents of the Lungs.

The absorbents of the lungs are very numerous, and, like
those of other viscera, are superficial and deep-seated.

The large superficial vessels run in the interstices between
the lobuli, and, therefore, form angular figures of considerable
size. In successful injections, the vacancies within these figures
are filled up with small vessels, and the whole surface appears
minutely injected.

Mascagni observes, that the superficial vessels are very
visible when any fluid has been effused into the cavity of the
thorax; or when warm water is injected, either into the blood-
vessels of the lungs, or the ramifications of the trachea. Cruik-
shank demonstrated them by inflating the lungs of a still-born
child ; in which case the air passes rapidly into them.

The deep-seated absorbents accompany the blood-vessels and
the ramifications of the bronchise. They pass to the dark-col-
ored glands, which are situated on the trachea at its bifurcation ;
and on those portions of the bronchia which are exterior to the
lungs. The injection of the absorbents, which pass to and from
these glands, seem to prove that they are of the same nature
with the absorbent glands in general, notwithstanding their color.
They are numerous ; and they vary in size, from a diameter of
two lines to that of eight or ten.

From these glands, some of the absorbents of the left lung
pass into the thoracic duct, while it is in the thorax, behind the
bifurcation of the trachea ; others proceed upwards and enter
into it near its termination ; while those of the right lung
terminate in the common trunk of the absorbents of the right
side.

364 ABSORBENTS OF THE HEAD AND NECK.

CHAPTER XI.

OF THE ABSORBENTS OF THE HEAD AND NECK ; OF THE UPPER
EXTREMITIES, AND THE UPPER PART OF THE TRUNK OF
THE BODY.

The absorbents from the various parts of the bead pass
through glands, which are situated on the neck or the lower
part of the head. Those on the head are the least numerous,
and also the least in size. Some of them, which are generally
small, lie about the parotid gland. Several of them, which are
also small, are on the occiput, below and behind the mastoid
process. Sometimes there are two or three on the cheek, near
the basis of the lower jaw, about the anterior edge of the mas-
seter muscle. Below the lower jaw, in contact with the sub-
maxillary gland and anterior to it, there are always a number
of these glands, which are generally small, but often swelled
during infancy.

The Glands on the Neck are the most numerous. Many of
them are within the sterno-mastoid muscle, and accompany
the internal jugular vein and the carotid artery down to the
first rib. Many also lie in the triangular space between the
sterno-mastoid muscle, the trapezius, and the clavicle; therefore
it has been truly said that the glands of the neck are more
numerous than those of any other part except the mesentery.
They are frequently called Glandulce Concafenata. It has
already been mentioned that the various absorbents, which are
connected with these glands, unite on each side into a trunk,
which on the left passes into the thoracic duct, and on the right
into the common trunk of the absorbents of that side.

Of the Absorbents of the Head and Neck.

There is the greatest reason to believe that the brain and its
appendages are supplied with absorbents like the other parts.

k^

ABSORBENTS OF THE UPPER PART OF THE TRUNK. 365

Some of these vessels have been discovered in the cavity of the
cranium; but very little precise information has as yet been
obtained, respecting the extent, or arrangement of the absorb-
ent system, in this part of the body.

The absorbents on the exterior of the head are as numerous
as in other parts of the body. On the occiput they pass down,
inclining towards the ear, and continue behind it to the side of
the neck ; behind the ear they pass through several glands.
From the middle or temporal region of the cranium, they pass
with the carotid artery before the ear, and enter some small
glands that lie on the parotid ; from which they continue to
the neck.

They are on every part of the face, and unite, so that their
principal trunks, which are very numerous, pass over the basis
of the lower jaw, near the facial artery. They enter into
glands, which are also very numerous, immediately under the
jaw, or which are sometimes to be found on the cheek, at the
anterior edge of the masseter muscle. All the absorbents of
the exterior part of the head pass to the glands on the side of
the neck, already described.

Those from the interior of the nose accompany the ramifica-
tions of the internal maxillary artery, and proceed to glands
behind the angle of the lower jaw ; into which glands also enter
the absorbents of the tongue and inner parts of the mouth.

The absorbents of the thyroid gland, on the left side, pass
down to the thoracic duct ; those on the right, unite to the
trunk of the absorbents on that side, near its termination. It
has been remarked, that they can be readily injected, by
thrusting the pipe into the substance of the gland.

Of the Absorbents of the Arm and Upper Part of the Trunk,

The absorbents of the arm are superficial and deep-seated,
like those of the lower extremity.

The superficial absorbents have been injected on the ante-
rior and posterior surfaces of the fingers and the thumb, near
their sides. On the back of the hand they are very numerous,
and increase considerably in their progress up the fore-arm.
31*

366 ABSORBENTS OF THE ARM AND UPPER PART OF THE TRUNK.

As they yKoceed upwards, ihey incline towards the anterior
surface of the fore-arm ; so that by the time they have arrived
at the elbow, almost all of them are on the anterior surface.
Tlie absorbents on the anterior part of the hand are not so
numerous as those on the back. Sometimes there are digital
branches from the fingers, and an arcus in the palm ; but this
bow is not formed by one large absorbent, analogous to the
ulnar artery. On the contrary, its two extremities are con-
tinued over the wrist, and pass on the fore-arm like the
absorbents.

At the elbow some of them often pass into one or two small
glands, which are very superficial ; but the whole of the
absorbents, somewhat reduced in number, as some of them
unite together, pass along with the blood-vessels into the hollow
of the arm-pit, where they enter the axillary glands. There
are generally one or more vessels which pass in the course of
the cephalic vein, between the pectoral and the deltoid muscle,
and enter into some of the glands under the clavicle.

There are almost always several glands in and near the
axilla. Some of them are very near the great blood-vessels ;
sometimes one or more of them are much lower ; sometimes
they are to be found under the pectoral muscle. They are
commonly not so large as those of the groin, and are surrounded
with fat.

The deep-seated absorbents originate also at the fingers, and
soon accompany the branches of the arteries. Those which
attend the radial artery, originate on the back of the hand, and
also in the palm, where they are associated with the arcus
profundus. They go up with the radial artery to the elbow,
and sometimes pass through a small gland about the middle of
the fore-arm.

Those which attend the ulnar artery, commence under the
aponeurosis palmaris, and go with the artery to the elbow ; at
the bend of the elbow they are generally joined by one or
more, which accompany the interosseal artery; there they
unite, so as to form several trunks, which pass up to the axilla
with the humeral artery. They sometimes pass through one

RIGHT BRACHIO-CEPHALIC TRUNK. 367

or two glands, which are near the elbow; and they receive in
their course, deep-seated branches from the muscles on the
humerus.

The absorbents from the anterior and external part of the
thorax, and the upper part of the abdomen, also proceed to the
axilla, and enter into the glands there : those which are deep-
seated joining the deep-seated vessels. The absorbents of the
mammae pass to the same glands ; and when they are affected
with the virus of cancer, can often be perceived, in their course,
in the living subject.

The absorbents of the uppermost half of the back, and those
of the back of the neck, go likewise to the axilla.

The absorbent vessels, collected from these various sources,
proceed from the exterior to the innermost glands, but with a
considerable diminution of their number : they accompany the
subclavian vein, and are reduced to one or two trunks, that
generally unite before their termination. On the left side, the
absorbents of the head and neck generally open into the tho-
racic duct, as has been already observed ; and those of the left
arm also open into the thoracic duct, or into the subclavian
vein very near it. On the right side the absorbents from each
of these parts empty into the common trunk, which often is
formed by the union of large vessels, from four sources, and
called brachio cephalic ; namely, the head", the thyroid gland,
the right arm, and the right cavity of the thorax. The
diameter of the trunk is very considerable ; but it is often not
more than half an inch in length. It generally opens into the
right subclavian vein, at the place where it unites to the right
internal jugular.

Two respectable physiologists of Europe, (M. Seguin, of Paris and the late Dr.
Currie of Liverpool,) have doubted whether absorption takes place on the
external surface of the skin.* This question has been examined in a very
interesting manner by several graduates of the University of Pennsylvania,

* I believe that M. Seguin's Memoir on this subject was read to the Academy of Sciences
a short time before the meetings of that body were suspended. It was published by M.
Fourcroy, in La Medicine Eclairee par les Sciences Physiques, vol. iii. An extract from M.
Fourcroy's publication may be seen in the J9th chapter of the first volume of Dr. Currie's
" Medical Reports on the Effects of Water," &c., in which is also contained a statement of
the Doctor's own experiments and reflections.

36S FACTS RELATING TO CUTANEOUS ABSORPTION.

who chose it for the subject of their inaugural theses ; namely, Drs. Rous-
seau, Klapp, Daingerfield, Mussey, and J. Bradner Stewart.

The three first of these gentlemen state that when spirit of turpentine, and
several other substances which are commonly supposed to be absorbed by the
skin, were applied to it in a way which prevented their volatile parts from
entering the lungs by respiration, no absorption took place. But when the
inspireil air was impregnated with exhalations from these substances, they
perceived satisfactory proofs that the exhalations entered the system. From
these facts they inferred that when those articles entered the body by absorp-
tion, ihey were taken in by the lungs, and not by the external surface.

On the 01 her hand, the two gentlemen last mentioned, state that after immers-
ing themselves in a bath consisting of a decoction of rhubarb, of madder,
or of turmeric, their urine became tinged with these substances. They also
assert that the coloring matter of these different articles is not volatile ; and,
therefore, could not have entered the lungs during the experiments.*

The statement in page 301, from Dr. Soemmering, that when mercury is in-
jected backwards in the absorbent vessels which originate on the foot, it will
sometimes appear in small globules on the skin of the foot, has an important
connexion with this subject.f

About the middle of the last century, it was generally believed by anatomists
that absorption was performed by the veins. This doctrine seemed to be
established by the experiments of Kaaw Boerhaave, which are related with
many other interesting statements, in his work, entitled " Perspiratio Dicta
Hippocrati," &c., published at Leyden, in 1738. In these experiments it
appeared to the author, that when the stomach of a dog was emptied of its
contents, and filled with warm water, immediately after death, the water
passed into the minute ramifications of the veins of the stomach, and from
them to the vena portarum, and ultimately to the heart in large quantities.

This account appears to be disproved by some experiments of the late John
Hunter, made about twenty years after, and published in the Medical Com-
mentaries of Dr. William Huuter, part I.— Mr. Hunter's experiments have
been considered as establishing the fact, that absorption, (in the intestines at
least,) is performed exclusively by the lacteals, or proper absorbent vessels,
and not at all by the veins. Kaaw Boerhaave is of course supposed to
have been mistaken ; and Mascagni, who has repeated his experiments,
refers the appearance of water in the veins to transudations through the coats
of the intestines ; which he has observed to take place in a great degree.

In the year 1809, a memoir was presented to the national institute of France
by Messrs. Blagendie and Delile, which contains an account of some experi-
ments that have an important relation to the above mentioned subject.^: —

* The Thesis of Dr. Rousseau was published iu 1800. Those of Drs. Klapp and Dainger-
field in 1805. Dr. Mussey published in the Third Supplement to the Medical and Physical
Journal of Dr. Barton in 1809. Dr. Stewart published in 1810. Additional Observations by
Drs. Klapp, Rousseau and Smith, are published in the Philadelphia Medical Museum, vol. i.
new series.

t Since the publication of the first volume the author has enjoyed the advantage of con-
sultino- a translation, in manuscript, of some parts of the German edition of Dr. Soemmer-
ing's valuable work on the Structure of the Human Body.

t The title of the paper is a " Memoir on the Organs of Absorption in Mammiferous Ani-
mals." A translation of it was published in the Medical and Philosophical Register of New
York, and in several other periodical works.

EXPERIMENTS OF BOERHAAVE AND HUNTER. 369

The authors being greatly surprised at the rapiJity with which the pois^on of
Java, 6cc., appeared to enter the sanguiferous system, instituted a series of
experiments to determine whether these substances proceeded to that system
by the circuitous route of the absorbent vessels, or by the shorter course of
the veins. Two of their experiments are especially interesting. They made
an incision through the parietes of the abdomen of a living dog, who had
eaten a large quantity of meat some hours before, (that his lacteals might be
visible from their distention with chyle,) and drawing out a portion of the
small intestine, they applied two ligatures to it, at the distance of five inches
from each other. The portion of intestine between these ligatures was then
separated by incision from the rest of the intestinal tube, and all the lacteals
and blood-vessels, &:c., which passed to and from it, were divided, except one
artery and a vein. A considerable length of this artery and vein were de-
tached from all the surrounding parts, so that the authors supposed these
vessels to form the only connexion between the portion of the intestine^ and
the rest of the body. Into the cavity of the intestine, which was thus cir-
cumstanced, they introduced a small quantity of the poison, and, to their
astonishment, it produced its fatal effects in the same manner it would have
done if it had been introduced into the intestine while all its connexions with
the body were entire. This experiment, they assert, was repeated several
times, without any difference in the result.

After several other experiments, they finally separated the thigh from the body
of a living dog in such a manner, that the crural artery and vein were left
undivided. A quill was then introduced into the artery, and two ligatures
were applied to fix it round the quill. The artery was then divided between
the two ligatures. The vein was managed in the same manner. There was,
therefore, no communication between the limb and the body, except by the
blood which passed through the divided vessels and the quills. The poison
was then introduced under the skin of the foot, and soon occasioned the death
of the animal ; its deleterious effects commencing about four minutes after
its application to the foot. This experiment appears to prove decidedly that
the blood is the vehicle by which poison, when applied to the extremities, is
carried to the body ; although it may not determine the question whether this
poison was taken up by the absorbents or by the veins *

Some other experiments made by the authors gave results, which are very diffi-
cult indeed to explain. They wished to know if the blood of an animal thus
contaminated, would produce similar effects upon another animal ; and, with
a view to ascertain this point, they insinuated a small piece of wood, covered
with the poison, into the thick part of the left side of the nose of a dog.
Three minutes after the introduction of the poison, they transfused blood from
the jugular vein of the same side, into one of the veins of another dog.
About one minute after the commencement of the transfusion, the effects of
the poison began in the dog to which it was applied, and continued until his
death. Transfusion into the veins of the other dog went on during the whole
time, and he received a large quantity of blood from the dying dog, without
producing any effect. They varied this experiment in the following manner.
The thigh of a dog was separated from the body ; the artery and the vein

* Tliis experiment has been repeatefl in Philadelphia. See Professor Chapman's Medical
and Physical Journal for February, 1823, No. 10.— h.

STO THE ABSORBENT VESSELS.

were arranp;ed as in the former experiment ; and poison was introduced into
the foot. Three minutes after the introduction of the poison, the blood of the
crural vein was passed into the jugular vein of another animal and transfu-
sion was continued five minutes without producing any effect upon the animal
receiving the blood ; it was then stopped, and the crural vein was so arranged
that the blood flowed from it into the animal to which it belonged. This
animal very soon exhibited symptoms of the operation of the poison.*

From these very interesting experiments the authors infer that "foreign matters
do not always proceed through the Lymphatic or Absorbent Vessels, nhen they
enter into the Sanguiferous system."

This memoir was referred by the Institute to four of its members, who are
particularly distinguished by their profound knowledge of anatomy and phy-
siology. These gentlemen, after stating their belief that the functions of the
lymphatic or absorbent system have been completely ascertained by the ex-
periments and observations of Hunter, Cruikshank, Mascagni, ^c, say far-
ther, that in their opinion, the above mentioned inference ought to be a little
modified, and that facts are not sufficiently numerous, or applicable to the
point in question, to justify the inference xhdLt foreign matters do not always
proceed through the Lymphatic or Absorbent Vessels, rvhen they enter the Sangui-
ferous system. But Ihey also add, that as the author is still engaged in a
series of experiments on the subject, they will suspend their judgment
respecting the inferences to be deduced from the present staten.ent.

The most extensive account of the absorbent system is contained in the " His-
loria et Ichnographia Vasorum Lymphaticorum Corporis Hnmani" of Mas-
cagni,— " The Anatomy of the Absorbing Vessels of the Human Body, by
W. Cruikshank ;" — and " The Description of the Lymphatic System, by
William Hewson," (the second volume of his Experimental Inquiries,) are
also very interesting publications.

* An account of tliese experiments was published by M. Magendie in a pamphlet. A
statement of them is also contained in the report made to the Institute by the committee to
whom the memoir was referred, which is published in the Journal de Physique, for March,
1813. In that statement this last mentioned experiment is omitted.

A most interesting series of inquiries and experiments in regard to the laws of absorption
will be found in Professor Chapman's Journal of the Medical and Physical Sciences, No. 6,
in a report of a Committee of the Academy of Medicine, signed by Doctors Lawrence and
Coates, of this city. And a continuation of the same will be found in No. 10 of the same
Journal, signed by Doctors Lawrence and Coates. Since the publication of the latter, to
the regret of all who knew him, and to the great loss of Anatomy and of Physiology, the
indefatigable and excellent Lawrence is no more. — h.

k.

PART X.

OF THE BRAIN AND SPINAL MARROW : OF THE EYE AND

THE EAR.

CHAPTER XII.

OF THE BRAIN.

The whole of the soft mass, which fills the cavity of the
cranium, is called the brain. This mass is covered by three
membranes : two of which were called meninges or matres, by
the ancient anatomists : who believed that all the other mem-
branes of the body originated from them.

These membranes are denominated the Dura Mater, Tunica
Arachnoidea, and Pia Mater.

Of the Membranes of the Brain, and Sinuses of the Dura

Mater.

Dura Mater.

The Dura Mater encloses the brain and all its appendages,
and lines the different parts of the cranium. It consists of one
membrane of a very dense texture, which in several places is
composed of two or more lamina. It is the thickest and strong-
est membrane of the body, and is composed of tendinous fibres,
which have a shining appearance, particularly on its inner sur-
face. In many parts these fibres run in a variety of directions,
and decussate each other at different angles.

The dura mater adheres every where to the surface of the
cranium, in the same manner as the periosteum adheres to the

372 DURA MATER.

bones in the other parts of the body ; but is more firmly con-
nected at the sutures and foramina than elsewhere ; and so much
more firmly in children than in adults, that In separating it fi-om
the cranium, it is apt to bring along with it some of the fibres of
the bone to which it is attached. In the adult, the separation
of the bone from the membrane is less difficult, in consequence
of many of the fibres being obliterated ; although in old age the
adhesion is sometimes very strong.

The inner surface of the dura mater, which is remarkably
smooth, is in close contact with the brain, but adheres only
where the veins go into the sinuses ; and is lubricated by a fluid
discharged through its vessels, which guards the brain from
danger, according as it may be affected by the different states of
respiration.

The dura mater serves as a defence to the brain, and supplies
the place of a periosteum to the inside of the cranium ; giving
nourishment to it, as is evident from the numerous drops of
blood which appear after removing a portion of it from the
bone.

The proper blood-vessels of the dura mater are not very
numerous. Its arteries are derived partly from the external
carotids, and partly from the internal carotids and the vertebral
arteries. Corresponding veins accompany these arteries ; but
the dura mater by the separation of its two lamina forms also
reservoirs, that contain the venous blood, which is brought from
the substance of the brain. These are called sinuses, and are
very different from common veins.

Nerves have been traced into the dura mater by the French
anatomists, derived from the sympathetic in the neck. There
have been disputes respecting its sensibility ; but there is reason
to believe that in a sound state it has very little.
— Nervous fibrils have been likewise traced into the dura mater,
from the fourth pair and from several branches of the fifth. —
The dura mater sends also a cylindrical prolongation through
the basilar foramen to the margin of which it is closely adhe-
rent, and down the vertebral canal, to enclose the medulla
spinali. It sends also tubular prolongations over each of the

TUNICA ARACHNOIDEA. PIA MATER. 373

nerves as it passes out the foramina of the cranium and spine,
to assist in forming their neurileraa or sheath. —

Tunica Arachnoidea.

The Tunica Arachnoidea is an exceedingly thin, tender,
and transparent membrane, in which no vessels have been
hitherto observed.

It is spread uniformly over the surface of the brain, enclosing
all its convolutions, without insinuating itself between any of them.

At the upper part of the brain it adheres so closely to the
subjacent coat by fine cellular substance, that it can scarcely be
separated from it ; but in different parts of the base of the brain,
particularly about the tuber annulare and medulla oblongata,
it is merely in contact with the membrane under it, and may
readily be raised from it by the assistance of the blow-pipe.
— The Tunica Arachnoidea belongs to the class of serous
membranes and forms a double sac — one covering the surface
of the brain or rather of the pia mater, and the other giving an
internal polished facing to the dura mater. It does not however like
the pia mater pass in to line the ventricles. — A separate arachnoid
membrane is formed in these cavities. The arachnoid of the
outer surface of the brain passes down through the basilar fora-
men, to form one of the coverings of the spinal marrow. A
loose cellular tissue serves to connect it to the pia mater, both of
the brain and spinal marrow, which contains in the healthy state
a limpid secretion, amounting to one and a half or two ounces
called the sub-arachnoid fluid, which is supposed to serve as a
protection to the delicate cerebro-spinal mass. The greater
looseness of the arachnoid above noticed over the anterior part
of the tuber-annulare and the medulla ablongata, form what are
called, the anterior and posterior sub-arachnoid spaces. A third
space called the superior is found above the tubercula quadri-
gemina. The looseness of the arachnoid over the spinal marrow
forms a spinal sub-arachnoid space of considerable dimensions.

Pia Mater.
The Pia Mater, named from its tenderness, is an extremely
vascular membrane, made up exclusively of vessels and a deli-
cate cellular tissue which unites them together.
VOL. II. 32

374 PROCESSES OF THE DURA MATER.

It covers the brain in general, enters double between all its
convolutions, and lines the different cavities called ventricles.

It serves to conduct and support the vessels of the brain, and
allows them to divide into such minute parts, as to prevent the
blood from entering the tender substance of this viscus with too
great force.

The arteries of the pia mater are the same with those of the
brain and are derived from the internal carotids and vertebrals.

The veins differ in no respect from those of the other viscera,
excepting in this, that they do not accompany the arteries.

— It gets its nerves from the branches of the sympathetic
which attend the blood-vessels. Both it and the tunica arach-
noidea send cylindrical prolongations down the vertebral canal,
which surround the medulla spinalis.

— The pia mater is changed in character so as to become a
fibrous membrane, as it passes down over the crura cerebri,
the pons varolii and the spinal medulla, which latter it closely
embraces. —

Processes of the Dura Mater.

From the dura mater certain membranous processes go off,
forming incomplete partitions, which partially divide the cavity
of the cranium ; and in the same partial manner, separate the
parts of the brain from each other : thus preventing them from
pressing upon each other, and keeping them steady.

They are formed of the internal lamina or layer of the dura
mater, like a plait, and therefore each of them consists of a
double membrane.

The most conspicuous of these is denominated the falv,
which extends from the anterior to the posterior part of the
cranium, and divides the upper part of the brain into two
hemispheres ; but it is not sufficiently deep to divide the whole
of the brain : for, between the under edge of it, and the base
of the cranium, there is a large space occupied by a portion of
the brain, which is undivided : and, therefore, common to both
hemispheres.

The falx begins at the middle of the sphenoid bone, and,
continuing its origin from the crista galli of the ethmoid bone,

FALX MAJOR. TENTORIUM. FALX MINOR. 375

runs along the upper and nnidclle part of the head ; adhering
first to the frontal, then to the joining of the parietal, and after-
wards to the middle of the occipital bone.

In its passage it becomes gradually broader, and terminates
behind, in the middle of the tentorium.

It runs from before backwards in a straight direction, and
has some resemblance in shape to a sickle or scythe, placed with
its edge downwards ; from which circumstance it has obtained
the name o{ falx.

After extending backwards as far as the centre of the crucial
ridge, on the internal surface of the occipital bone, it extends
to each side, and forms a horizontal partition, which partially
divides the lower part of the cavity from the upper: but it does
not extend so far forward, as to separate, completely, the mass
which is under it, or the cerebellum, from the upper part of the
brain, or cerebrum.

This horizontal membrane is called the tentorium and also
the transverse septum : it is connected behind to the inner
transverse ridges and grooves of the occipital bone, and, at the
fore and outer edges, to the ridges and great angles of the tem-
poral bones, and terminates at the posterior clinoid process of
the sphenoid bone.

Between the inner edge of the tentorium and the posterior
clinoid process of the sphenoid bone, there is a large notch, or
oval foramen, where the brain and cerebellum are united, or
where the tnher annulare is chiefly situated which unites them.

The tentorium keeps the falx tense, and forms a floor or vault
over the cerebellum, which prevents the cerebrum from pressing
upon it.

The falx minor, or septum cerebelli, is placed between the
lobes of the cerebellum. It descends from the under and back
part of the falx in the middle of the tentorium, adheres to the
inferior longitudinal spine of the os occipitis, and terminates
insensibly at the edge of the foramen magnum of that bone.

Besides the process of the dura mater already described,
there are four of inferior consideration ; two of which are situ-
ated at the sides of the sella turcica, and two at the edges of
the foramina lacera.

376

SINUSES.

Sinuses of the Dura Mater.

As these partitions arise like plaits from the internal surface of
the dura mater, there must necessarily be a cavity, larger or
smaller, between the external layer of the dura mater, which lines
the internal surface of the cranium, and the basis of the partition
or process which arises from it : this cavity must continue along the
whole basis of the partition, and a section of it will be triangular.

Fig. 185.*

This cavity is of considerable size at the upper edge of the
falx, where it rises from the dura mater, and also where it forms
the tentorium ; and at the posterior edges of the tentorium,
where it adheres to the occipital bone.

The cavity at the upper edge of the falx is called the longi-
tudinal si7ius ; that at the posterior edge of the tentorium forms
two cavities, called the lateral sinuses ; and that which is at the
junction of the falx and tentorium has the name of the torcular,
or press of Herophilus ; so named, from a supposition enter-
tained by the older anatomists, that the columns of blood, com-
ing in different directions, compressed each other at this point.

* The sinuses of the upper and back part of the skull. 1. The superior
longitudinal sinus. 2, 2. The cerebral veins opening into the sinus from be-
hind forwards. 3. The falx cerebri. 4. The inferior longitudinal sinus. 5.
The straight or fourth sinus. 6. The vense Galeni. 7. The torcular Herophili.
8. The two lateral sinuses, with the occipital sinuses between them. 9. The
termination of the inferior petrous sinus of one side. 10, The dilatations cor-
responding with the jugular fossae, il. The internal jugular veins.

■^

SINUSES. 377

The veins of the brain open into these sinuses ; and the blood
flows through them into the internal jugular veins. They differ
from veins principally in this : that they are triangular, and, by
the tension of the dura mater, are protected from pressure.

The principal sinuses are,

1. The longitudinal sinus, which begins at the crista galli,
and, running along the upper edge of the falx until it arrives at
the tentorium, increases gradually in size, and terminates in the
two lateral sinuses. [In this sinus, and beneath the dura mater
near the top of the head, are many small bodies of various sizes
called glandulse Pacchioni. They are of various dimensions,
from a line and less to three or four lines in diameter. One of
the largest of these glands on each side protrudes through the
dura mater from the surface of the brain, and makes a pit in
the OS parietale. Vesalius demonstrated these bodies in 1543.
Pacchioni also demonstrated them fifty years afterwards ; and,
claiming them as a discovery of his own, succeeded in attaching
his name to them.]

2. The two lateral sinuses run in depressions of the occipital
and temporal bones, until they terminate in the internal jugular
veins at the foramen lacerum.

3. The torcular Herophili, which receives a large vein from
the interior of the brain, formed by the union of the two vena
Galeni, and is situated at the junction of the falx and tentorium,
opening into the longitudinal sinus, where it divides into the late-
ral sinuses.

These are the larger sinuses of the dura mater ; but, in addi-
tion to these, there are several small sinuses : as,

4. The inferior longitudinal sinus, which is situated at the
under edge of the falx, and receives blood from the central parts
of the cerebrum ; it terminates in the torcular Herophili, near
the beginning. The other small sinuses are situated under the
brain ; viz.

5. The circular sinus of Ridley,* which frequently surrounds
the pituitary gland, and carries the blood from the contiguous
parts to the

* An English anatomist, who flourished near the end of the 17th century.

32*

3T8

CEREBRUM.

6. Cavernous sinuses, which are placed at the sides of the
sella turcica, surrounding the carotid arteries and the sixth pair

'ISC.

186.

of nerves, and receive blood
from the circular sinuses the oph-
thalmic veins and several con-
tiguous parts, and discharge it into
the

7. Inferior petrous sinuses,
which are placed at the bases of
the partes petrosae, and discharge
this blood into the ends of the
lateral sinuses. To these should
be added

8. The superior petrous sinu-
ses, which are situated on the up-
per edges of the petrous bones.
They communicate both with the
lateral and the cavernous sinuses,
and receive some small veins from
the adjacent parts.

There are also several small sinuses near the great occi-
pital foramen, which communicate with the lateral sinuses,
and also with the vertebral veins. They are called occipital
sinuses.

The brain or the whole of the soft substance contained within
these membranes, is composed of four portions, viz., cerebrum,
cerebellum, tuber annulare or pons Varolii, and medulla oblon-
gata.

Of the Cerebrum.

The cerebrum completely fills the upper part of the cavity of
the cranium. It has some resemblance to the half of an egg,
which has been divided horizontally ; and is composed of two

* The sinuses of the base of the skull. 1. The ophthalmic veins. 2. The
cavernous sinus of one side. 3. The circular sinus ; the figure occupies the
position of the pituitary gland in the sella turcica. 4. The inferior petrous
sinus. 5. The transverse or anterior occipital sinus. 6. The superior petrous
sinus. 7. The internal jugular vein. 8. The foramen magnum. 9. The occi-
pital sinuses. 10. The torcular Herophili. 11, 11. The lateral sinuses.

CEREBRUM. 379

equal parts, which are separated vertically from each other by
the falx. This vertical separation does not extend through the
centre of the cerebrum, although it divides it completely before
and behind. A portion of the central part of the cerebrum ;
which is situated deeper than the under edge of the falx, is not
divided.

The upper surface of the two hemispheres is convex. The
under surface is rather irregular; it is divided in each hemi-
sphere into three lobes : the anterior, the middle, and the
posterior*

The anterior lobes of the brain are situated on the front part
of the base of the cranium, principally on the orbitar processes
of the OS frontis.

The middle lobes are lodged in the fossae formed by the tem-
poral and sphenoid bones.

The posterior lobes rest chiefly upon the tentorium, over
the cerebellum.

Between the anterior and middle lobes is a deep furrow,
corresponding to the base of the cranium on which they rest,
which is called the fossa Sylvii.

The surface of the brain resembles that of a mass of small
intestines, or of a convoluted cylindrical tube : it is, therefore,
said to be convoluted. The fissures between these con-
volutions do not extend very deep into the substance of the
brain.

The whole surface of the brain, thus convoluted, is covered
by pia mater ; which is connected to every part of the surface
by an infinite number of small vessels and processes, that
appear when this membrane is peeled off from the surface of
the brain.

The mass of the brain consists of two substances of different
colors ; one of which is, for the most part, exterior to the
other. The exterior substance is of a light brown color,
and is therefore called cineritious, or cortical, from its situa-
tion.

The internal substance is whhe, and is denominated the
medullary.

380 CORPUS CALLOSUxM,

The proportion of this medullary part is much greater than
that of the cortical. The cortical, however, surrounds it, so as
to form the whole of the surface of the cerebrum, that can be
strictly said to be exterior.

The color of the cortical part appears to be derived from
the blood ; as its intensity seems regularly proportioned to the
quantity of blood in the head. In subjects who have been
plethoric, or have had a determination of blood to the head ; it
is uniformly high-colored ; in pallid and exhausted subjects it is
of a fainter color.

The medullary matter is uniformly white ; but small red
points appear upon its surface, when cut, which are the sec-
tions of vessels which carry red blood ; and these points are
larger and more numerous in plethoric, than in exhausted
subjects. It is rather firmer than the cortical substance.

These two substances are most intimately connected in the
cerebrum, and indeed seem to be a continuation of each other.
In some parts they are blended together ; and in other places,
there are portions of cortical matter within the medullary.

The division of the cerebrum into two hemispheres extends
to a considerable depth from above, and also to a considerable
distance internally, from its anterior and posterior extremities ;
of course, the part which is undivided is in the centre.

The cortical part covers also the surfaces, which are in the
great fissure that forms the two hemispheres, and is occupied,
in a great degree, by the falciform process of the dura mater.
Towards the bottom of this fissure, and below the falx, these
surfaces being opposed to each other, and in contact, are slight-
ly united by adhesion of the membranes that cover them.

The central part, which is not divided, and which must
appear at the bottom of the fissure, when the two hemispheres
are separated from each other, is medullary ; being evidently
a union of the medullary matter of each hemisphere. This
undivided medullary part is equal to about one half of the
length of the hemispheres ; the fissures at each extremity ex-
tending inwards, about one-fourth of their length. On each
side of it, a fissure, equal to it in length, extends horizontally

LATERAL VENTRICLES. 381

into the medullary matter in each hemisphere, about half an
inch ; the whole of this unconnected surface, the middle of
which is directly at the bottom of the great fissure, is termed
corpus calhsum.

When the hemispheres are cut away to the level of this sur-
face, and the corpus callosum is examined, two raised lines
appear in the middle, which extend from one end of it to the
other ; and between them is a small groove of the same length.
This groove is called the raphe, or suture of the corpus callo-
sum. From the raised lines or bands on each side of the raphe,
small lines less elevated pass across the corpus callosum, and
are lost in the medullary matter. The hemispheres being thus
cut off at the level of the corpus callosum, on the cut surface is
to be seen the interior mass of medullary matter, with the cor-
tical part exterior, its edge exhibiting the convoluted surface of
the brain, and the pia mater, following the convolutions.

The medullary surface, thus exhibited, with the corpus cal-
losum in the centre, is denominated the centrum ovale.

The Ventricles.

In the brain there are four cavities called ventricles : three
of these are formed in the substance of the cerebrum : the
fourth is situated between the cerebellum, the pons Varolii,
and medulla oblongata. The two largest are called the lateral
ventricles, from their situations ; the others are named, from
the order in which they occur, the third and the fourth ven-
tricles.

— Another ventricle has more lately been discovered called the
fifth. It is very small and is situated between the two layers
of the septum lucidum. It communicates downwards between
the anterior crura of the fornix with the cavity of the third
ventricle. —

The lateral ventricles are cavities of an extremely irregular
figure : they are situated in each hemisphere a little below the
level of the corpus callosum : and, with the exception of the
partition which separates them, are directly under it. They
commence anteriorly, nearly on a line with the termination of

382 CORPUS STRIATUM.

the fissure that separates the two hemispheres anteriorly ; and,
continue backwards ahnost as far as the commencement of the
fissure that separates them posteriorly : when they have attained
this length posteriorly, they form a considerable curve, first
outwards, then downwards, and afterwards forwards, so that
they terminate almost as far forwards as they commenced ; but
much deeper.

At the posterior part of their curve, when they incline out-
wards, previous to their turn downwards, a process or continu-
ation of the cavity extends backwards, almost as far as the
cerebrum does itself. These elongations are called the posterior
cornua or sinuses, or the digital cavities.

Each ventricle may, therefore, be divided into three parts,
viz. The portion under the corpus callosum ; the portion
which continues outwards and downwards, and terminates
below it : and the posterior portion.

It has been compared to a ram's horn, by some who have
contemplated particularly the upper and lower portions of the
cavity ; and by others who have had the whole extent in view,
it has been called tricornis.

The bottom, or lower surface of these cavities, is varied in
almost every part of its extent. The front part of the bottom
of each ventricle is a broad and convex eminence, which
becomes narrower as it proceeds backwards ; so that it resem-
bles a portion of a pear. It inclines outwards as well as back-
wards, so that the narrow posterior extremities of the two
bodies are farther from each other than the anterior broad ex-
tremities.

The color of these bodies is cineritious externally ; but
they are striated with medullary matter within, and therefore are
called corpora striata.

Between their posterior extremities are two other eminences,
which incline to the oval form, and have a white or medullary
color ; although their substance, when cut into, is slightly
striated : they are called the thalami nervorum opticorum.
These bodies are very near each other: and, being convex in
form, are in contact at the centre : they adhere slightly to each

llbi.

THALAMUS NERVI OPTICl. FORNIX.

383

other ; and this adhesion is called the soft commissure, (commis-

sura 7nolUs.)

The corpora striata, and the thalami nervorum opticorum
Fig. 187.* join each other at the exterior

sides of the thalami : where
they are in contact, there is
the appearance of a narrow
medullary band, which con-
tinues during the whole ex-
tent of their connexion : it
has been called, by some,
tenia semicircularis, from its
form ; by others, centrum ge-
minum semicirculare, and tenia
striata.

— A vein of considerable size
runs along the upper surface
of the tenia, formed from the
veins which emerge from the

corpus striatum and thalamus and which vein empties into the

vena galeni of the same side.

* The lateral ventricles of the cerebrum. 1, 1. The two hemispheres cut
down to a level with the corpus callosum so as to constitute the centrum ovale
majus. The surface is seen to be studded with the small vascular points —
puncta vasculosa ; and surrounded by a narrow margin which represents the
grey substance. 2. A small portion of the anterior extremity of the corpus
callosum. 3. Its posterior boundary ; the intermediate portion forming the
roof of the lateral ventricles has been removed so as to completely expose those
cavities, 4. A part of the septum lucidum, showing an interspace between its
layers — the fifth ventricle. 5. The anterior cornu of one side. 6. The com-
mencement of the middle cornu. 7. The posterior cornu. 8. The corpus stria-
tum of one ventricle. 9. The tenia semicircularis covered by the vena corporis
striati and tenia Tarini. 10. A small part of the thalamus opticus. 11. The
dark fringe-like body to the left of the figure is the choroid plexus. This
plexus is continuous by a small process of it which passes through the foramen
of Monro, with the cavity of the third ventricle. A bristle is passed across,
through the two foramina of Monro, the extremities of which rest on the cor-
pus striatum of each side. Figure 11 rests upon the side of the fornix ; this
side portion, terminates in the posterior crus of the fornix, which runs down
the middle cornu of the lateral ventricle by the side of the hippocampus major
and is (here caWed corpus Ji7)ibriatum. 12. The fornix. 13. The commencement
of the hippocampus major descending into the middle cornua. The rounded
oblong body in the posterior cornua of the lateral ventricle directly behind fig.
13 is the Ergot, or hippocampus minor.

384 FORNIX.

— A yellowish band called the tenia Tarini or horny band form-
ed by a thickening of the lining membrane of the ventricle over-
lays this vein. —

These surfaces constitute the bottom or floor of the first por-
tion of the ventricles, which is under the corpus callosum : upon
this floor is laid a thin lamen of the medullary matter, of a
triangular form, called the Fornix, which covers the thalami
nervorum opticorum, and is attached to them by a membrane ;
so that when the ventricles are opened, the bottom appears to
consist of the corpora striata, and the fornix.

The upper surface or roof of the ventricles is concave ; from
the middle of it, immediately under the raphe of the corpus
callosum, there proceeds downwards a partition of medullary
matter, which separates the two ventricles from each other.
This is called septum lucidum, from its being nearly transparent :
below, it adheres to the fornix, and anteriorly, it is continued
into the medullary matter, between the corpora striata. This
septum lucidum is formed of two lamina or plates, which are
separated from each other in the anterior portion of the septum,
and thus form a small cavity, which has communication with
the third ventricle of the brain.

The fornix is not perfectly flat, but accommodated to the sur-
face of the thalami nervorum opticorum ; its under surface is
rather concave, and its upper surface convex. The anterior
angle passes down between the most anterior parts of the tha-
lami nervorum opticorum, and is divided into two small portions
called its crura, which can be traced some distance in that part
of the brain.

The body of the fornix is attached to the surfaces of the
thalami nervorum opticorum on which it rests by a very
vascular membrane, that is spread over the thalami, and
called tela choroidea and velum interpositum. At the edges
of the fornix, there are many blood-vessels in the membrane,
arranged close to each other, which are called the plexus
choroides.

The posterior side or edge of the triangular fornix termi-
nates in the corpus collosum, or the medullary matter which

■M||^

PLEXUS CHOROIDES. 385

is above it at that jDlace ; but the under surface is attached
throughout to the parts on which it lies, by the aforesaid mem-
brane.

The two posterior angles of the fornix form what are called
the crura, and they terminate in the following way.

The surfaces of the inferior portions of the lateral ventricles
are not uniformly concave ; but at the bottom of each there is
a prominent body, which begins where this portion of the
cavity winds outwards and forward, and continues its whole
extent. This prominence has a curved form, and is marked by
transverse indentations towards its extremity ; hence it has
been termed the hippocampus, or cornu ammonis.

A similar prominence, but smaller, and without the trans-
verse indentations, is to be found in the posterior portion of
the ventricle : this has, also, been called hippocampus ; but the
terms major and minor are applied to distinguish them.

The posterior angles of the fornix terminate in the large
hippocampi ; and the margin or thin edge of the two anterior
sides of the fornix, is continued to form an edge to the hippo-
campus ; and is called the icEnia hippocampi, or corpus Jim-
hriatum.

The word fornix was the ancient name of a vault or arch ;
and, from its supposed resemblance to an arch, this part has
been called by that name.

When the fornix is raised up, which must be done by divi-
ding it at the anterior angle, and detaching it from the thalami
nervorum opticorum, the thalami by dissecting off the velum in-
terpositum, are brought fairly into view, and appear like oval
bodies placed parallel to each other. They adhere slightly at
their upper surfaces, and, when separated, a fissure appears
between them, which is the third ventricle. At the upper
and front part of this third ventricle, near its commencement,
before the anterior crura of the fornix, and very near them, is
a white chord, like a nerve, which passes across the ventricle,
and can be traced to some distance on each side of the medul-
lary matter of the brain.

This chord is called the anterior commissure of the brain.
VOL. II. 33

386 COMMISSURES OF THE BRAIN.

The thalami nervorum opticorum being of an oval form, and
touching each other in the middle, there must be a vacuity
between them at their extremities. This vacuity is behind
the anterior crura of the fornix, and has been called Vulva,
Iter ad Infundibulnm, and Iter ad Tertium Ventriculum.

It leads, of course, into the third ventricle ; but a passage
continues from it downwards and rather forwards, to the
infundibulum ; which is a process somewhat resembling a
funnel that is composed principally of cineritious substance,
and passes from the lower and front part of the third ventricle,
towards the sella turcica ; in which is situated the small body
called the Pituitary Gland.

The infundibulum is hollow at its commencement, and solid
at its extremity near the gland.

The adhesion of the thalami nerv. optic, to each other, at the
upper part of the third ventricle, has been denominated the
Commissura Mollis. The recession from each other at their
posterior extremities, in consequence of their oval figure, forms
another opening into the third ventricle when the fornix and
tela choroidea is raised, but which is closed when they are in
iheir natural situations upon it.

In the back part of the third ventricle is another medullary
chord, called the Posterior Commissure, which appears much
like the anterior commissure ; but does not extend into the
substance of the brain in the same way. Under this chord, or
posterior commissure, is a passage which leads to the fourth
ventricle, called Iter ad Q^uartum Ventriculum, or Aqueduct
of Sylvius.

Behind the third ventricle, and terminating it posteriorly,
are four. convex bodies, called Tubercula (^uadrigemina, or
Nates and Testes : the nates are uppermost and most convex ;
the testes are immediately below, and somewhat oval trans-
versely.

The nates and testes are situated so far backwards that they
are near the anterior part of the upper surface of the cerebel-
lum, and the anterior edge of the middle of the tentorium. The
posterior part of the fornix is directly over them, but it

COMMUNICATION OF THE VENTRICLES. 387

unites with the medullary matter of the cerebrum above it ;
there would, therefore, be a passage into the lateral ventricles
from behind, between the back of the fornix which is above,
and the nates and testes which are below ; but the velum inter-
positum passes in from behind, and attaches the lower surface
of the fornix to all the parts on which it lies ; and thus closes
the ventricles at this place. In this membrane, immediately
over the posterior end of the fissure called the third Ventricle,
and in contact with the nates, is the Pineal Gland. This body
is not so large as a pea, and is formed like a pine-apple, or the
cone of a pine tree.

When the fornix is raised by dissecting the membrane, it may
be elevated with the membrane and fornix.

The nature of this body is not understood : it resembles a
small gland in its appearance, but it is very soft ; and particles
of sand-like matter are often found in it.

There is a small chord on each edge of the third ventricle,
which appears to proceed from the pineal gland, and continues
on the edge of the ventricle to the anterior crura of the fornix,
to which it unites. These chords join each other under the
pineal gland: they are called the pedunculi, ov footstalks of the
pineal gland.

The membrane connected with the pineal gland, it has been
said, is the tela choroidea, or velum interpositum, in which the
plexus choroides is placed, at the edges of the fornix. This
membrane is extended, somewhat thinner and less vascular, so
as to line the surface of the ventricles. The plexus choroides
appears to begin at the end of each 'of the inferior portions of
the ventricles, where the pia mater penetrates from the basis of
the brain : it proceeds into the upper portions of the ventricles,
and continuing along the edge of the fornix, passes under that
body at its inferior angle, and meets the plexus of the opposite
side. Between this meeting of the plexus, and the crura of the
fornix, is a vacuity of an oval figure, which forms a communi-
cation between the ventricles of the brain. Under this vacuity
or foramen, the thalami nerv. optic, recede from each other,
and form the anterior passage into the third ventricle, described

388 THE CEREBELLUM.

at page 386, so that at this place the three ventricles communi-
cate with each other.

From the plexus choroides of each side, where it has
passed under the fornix at the anterior angle, a large vein is
turned backwards, so as to run nearly over the fissure of the
third ventricle towards the pineal gland. Several veins from
the surface of the ventricle join this vein near its commence-
ment ; thus formed, it passes along with the corresponding
vein from the opposite side, sometimes in contact and some-
times separated from it a small distance ; near the pineal gland,
these veins unite into one trunk, the great internal vein of the
brain, called the T-^ena Galeni : which terminates soon after in
the torcular Herophili.

Of the Cerebellum.

The cerebellum is situated in the lower and posterior part
of the cavity of the cranium, in contact with that portion of
the OS occipitis which is below the groove for the lateral sinuses.
It is, of course, much less than the brain.

It is covered above by the tentorium, and is divided below
into two lobes, by the falx minor.

The surface of the cerebellum differs in some respects from
that of the cerebrum. Instead of the convolutions, there are
small superficial depressions, which are nearly horizontal,
tending to divide the cerebellum into strata. The pia mater
extends into these depressions ; and the tunica arachnoidea
passes over them, as in the cerebrum.

The exterior part of the cerebellum is composed of cine-
ritious or cortical, and the interior of medullary matter, as is
the case with the cerebrum : but the proportions of these sub-
stances in the cerebellum, are the reverse of what they are in
the cerebrum.

If sections be made in the cerebellum, the medullary matter
is so arranged that it appears like the stem or trunk of a plant,
with ramifications extending from it. This appearance has
been called the Arbor vita.

PONS VAROLII. 389

On the basis of the brain is a part called Tuber Annulare, or
Pons Varolii, which is formed by processes from the cerebrum,
and cerebellum ; it is in contact with the anterior and inferior
portion of the cerebellum in the middle. From this part the
medulla oblongata proceeds downwards and backwards, under
the cerebellum : and between the cerebellum, the medulla ob-
longata, and the pons varolii, is the vacuity, called ihe fourth
ventricle of the brain.

When the brain is in its natural situation, this cavity is below
and behind the nates and testes ; and from the cerebellum there
passes up to the testes, a lamen of medullary matter, which
closes it above. This lamen is called the Valve of Vieussens,
or the Volve of the Brain. Below, the ventricle is closed by
a membrane, which connects the medulla oblongata to the cere-
bellum.

There is a passage into this cavity from the third ventricle,
which passes under the posterior commissure, the nates and
testes, entering the fourth ventricle below the testes.

Of the Basis of the Brain, and the Nerves which proceed

from it.

When the brain is detached from the basis of the cranium,
and inverted, (which can be readily done, if the nerves that
proceed from it are divided, as it is inverted,) the tunica arach-
noidea appears more conspicuous on the basis than it is on the
upper part ; the pia mater is disposed round the convolutions in
the same manner that it is above ; but the nerves and vessels
connected with the surface of the brain are so much involved
with these membranes, that considerable dissection is required to
expose them properly.

The anterior and middle lobes of the brain are very conspi-
cuous on the inverted surface. The anterior lobes appear separ-
ated from each other by the extension of the great fissure which
forms the two hemispheres. The middle lobes appear at some
distance from each other in the centre ; and the cerebellum forms
the posterior and most prominent part of the surface.

When the brain has been carefully detached from the cranium,
33*

390 BASIS OF THE BRAIN, AND NERVES PROCEEDING FROM IT.

and the nerves adhering to it are preserved, the olfactory or
first pair^**' of nerves appear on the anterior lobes, running nearly
parallel to each other at a small distance from the great fissure.
Tiiey are flat, and thin, and soft, in their texture ; their breadth
is rather more than one-sixth of an inch. They pass in
three divisions from between the anterior and middle lobes
of the cerebrum, which soon unite and run to the cribriform
plate of the ethmoid, where they expand into soft bul-
bous lobes, from which proceed the fibres that perforate the
cribriform plate, and are spread upon the Schneiderian mem-
brane.

Behind the olfactory nerves are the optic. Each of which
comes out between the anterior and middle lobes of the cere-
brum ; and after blending so as to meet its fellow, turns off
and passes through the optic foramen in the sphenoidal bone.
These nerves can be traced in the brain to the thalami nerv.
opticorum.

In the angle formed by the optic nerves posteriorly, is a mass
of softish cineritious matter (jpons Tarini) ; and also the infun-
dibulum which passes to the sella turcica.

In this soft cineritious matter are two round white bodies
that resemble peas ; they are called the Corpora Albicantia
of Willis or the Eminentice Mammillares. Behind these
bodies are two large medullary processes, called the Crura
Cerebri, which are best seen if some of the cortical part of the
adjoining middle lobes is dissected away. They come from
the medulla of the opposite sides of the brain, and gradually
approach each other until they arrive at the tuber annulare, or
pons Varolii.

The Pons Varoliif is a mass of considerable size, which has
a medullary appearance externally, but is striated within : it is
formed by the union of the two above mentioned crura cerebri,
and of two similar processes derived from the cerebellum, called
also its Crura. It lies over a part of the body of the sphenoid
bone, and of the cuneiform process of the occipital bone, and

* The nerves are numbered from before.

t Named from Varolius, physician to Gregory VIII. in 1573.

1^^

MEDULLA OBLONGATA. 891

under a portion of the middle lobes of the cerebrum and of the
cerebellum. There is a longitudinal depression on its surface,
made by the basilar artery ; and there are also many transverse
streaks on it.

The crura of the cerebellum, which runs into this substance,
are evidently continued from the arbor vitse or medulla of the
cerebellum.

The anterior edge of the cerebellum, part of which is in con-
tact with the pons Varolii, is remarkably prominent on each
side of it. These prominences are called the Vermes of the
cerebellum.

The medulla oblongata is continued backwards from the pos-
terior side of the tuber ; and somewhat resembles a truncated
cone inverted.

It lies on the cuneiform process of the occipital bone, and
extends to the- foramen magnum. It is indented lengthwise,
both anteriorly and posteriorly, by fissures which are very
evident : it is composed of medullary matter externally, and
cineritious matter within.

On each side of the anterior fissure, which is in view when
the brain is inverted, are two oblong convex bodies : those
which are next to the fissure are called the Corpora Pyrami-
dalia, and are the longest ; the two exterior are called Corpora
OUvaria, and are not so long.

The third pair of nerves come from between the crura of the
cerebrum, and pass forward, diverging from each other. They
proceed by the cavernous sinus, and, after penetrating the dura
mater, go out of the cranium at the foramen lacerum.

The fourth pair, the smallest nerves of the brain, resemble
sewing thread in their size and appearance. They come out
between the cerebellum and pons Varolii, but can be traced
backwards as far as the testes. They proceed forwards by the
sides of the pons Varolii, and after penetrating the dura mater
near the posterior clinoid apophysis, pass through the foramen
lacerum to the trochlearis muscles of the eye.

^\\Q fifth pair, the largest of the brain, arise from the crura
of the cerebellum, where they unite with the pons varolii : they

392 NERVES OF THE BRAIN.

pass forwards and downwards, and penetrate the dura mater
near the point of the petrous portion of the temporal bone.

This nerve appears Hke a bundle of fibres ; and, under the
dura mater, forms a plexus ; from which its three great branches
proceed to their destination.

The sixth 'pair arise from the medulla oblongata, where it
joins the pons varolii. It is often composed of two chords on
each side, one of which is very small ; they pass under the
pons Varolii, and through the cavernous sinus, with the carotid
artery : after emerging from this sinus they proceed through
the foramen lacerum to the abductor muscles of the eye. In
this course a small twig passes from it, which accompanies the
carotid artery through the canal in the petrous portion of the
temporal bone, and with a twig from the fifth pair, is the origin
of the intercostal nerve.

The seventh pair appear at the side of the medulla oblongata,
near the pons Varolii. It is composed on each side of two
chords, called Portia Dura and Portio Mollis, and of one or
more small fibres between them, called Portio Media. The
portio mollis can be traced to the fourth ventricle. The portio
dura seems to arise from the place of union of the pons Varolii
with the medulla oblongata and the crura cerebelli. The portio
media appears to originate in the same neighborhood, and
may be considered as an appurtenance of the portio dura.
They all proceed to the meatus auditorius internus, as it has
been called, in the temporal bone.

The eitrhth pair of nerves arise from the corpora olivaria on
the side of the medulla oblongata. They are composed in each,
of one chord called the Glosso-Pharyngeal, and of a conside-
rable number of small filaments, which unite and form another
chord called the Par Vogim.

With these nerves is associated a third chord, called the
Spinal Accessory Nerve of Willis, which passes up the spinal
cavity, being composed of twigs from the posterior and ante-
rior portions of almost all the cervical nerves.

The par vagum, with this nerve and the glosso-pharyngeal,
proceeds from its origin to the foramen lacerum formed by the

EIGHTH AND NINTH PAIR OF NERVES. 393

occipital and temporal bones ; where they all pass out of the
cranium ; separated from each other, and from the internal
jugular vein, by small processes of the dura mater.

Their destination is extremely different. The glosso-pharyn-
geal is spent upon the tongue and pharynx ; the par vagum
upon the contents of the thorax and abdomen, &tc., while the
accessory branch, which seems to have no connexion with them,
perforates the sterno-mastoid muscle, and is distributed among
the muscles of the shoulder.

The ninth pair arise from the corpora pyramidalia by many
filaments, that are united on each side into three or four fasciculi,
which perforate the dura mater separately, and then unite to pass
out of the anterior condyloid foramen of the occipital bone :
this pair is spent upon the muscles of the tongue.

Within the last three or four years, there have been many allusions in the
public papers, to the discoveries of Dr. Gall, formerly of Vienna, respecting the
brain. For information concerning these discoveries, the reader is referred to
a very learned and judicious Memoir, presented to the class of Mathematical
and Physical Sciences of the National Institute of France, by Messrs. Tenon,
Portal, Sabatier, Pinel, and Cuvier.

A translation of this report has been published in the fifth volume of the
Edinburgh IMedical and Surgical Journal for 1809. See, also. Lessons in Prac-
tical Anatomy by the present editor, part I.

Galen taught that there were two motions in the brain, one caused by the
pulsation of the arteries, the other by respiration, the air being admitted into
the ventricles through the ethmoidal and sphenoidal cells. Vasalius and Fallo-
pius refuted the latter opinion and exposed ils error. In 1744, Mr. Schlich-
ting, of Amsterdam, announced to the Royal Academy of Sciences of Paris,
that the brain was elevated in expiration and depressed in inspiration. MM.
Haller and Lamard repeated his experiments, and found that the motion of
the brain depended on a reflux of blood through the internal jugulars, in cases
of laborious respiration, besides the common motion from the pulsation of the
arteries. — See Discours sur I'Anatomie par Lassus. — h.

394

SPINAL MARROW.

CHAPTER XIII.

OF THE SPINAL MARROW.

The medulla oblongata is continued from the cavity of the
cranium, through the great foramen of the occipital bone, into
the great canal of the spine ; when it takes the name of Medulla
Spinalis or Sjjinal Marrow.

The dura mater passes with it through the great foramen,
and encloses the whole of it. At the commencement of the
spinal canal this membrane is attached to the surrounding
bones ; viz. to the margin of the great occipital foramen, and
to the atlas ; but below this it is loosely connected by a mem-
brane which sometimes appears to contain a little adeps. The
tunica arachnoidea and the pia mater also invest the medulla
spinalis. The arachnoidea appears unconnected with the
dura mater ; and it can easily be removed from the pia
mater. The pia mater adheres rather firmly to the substance it
encloses.

The spinal marrow consists of medullary matter externally,
and cineritious or cortical matter internally.

The fissures which are observable, anteriorly, and posteriorly,
in the medulla oblongata, are continued down the spinal mar-
row ; dividing it partially into two lateral portions : these fissures
penetrate to a considerable depth. Each of the lateral portions
is marked on its external surface, by a more superficial fissure,
which partially divides it into an anterior and posterior part ;
so that a transverse section of the spine has a cruciform ap-
pearance.

The nerves go off in fasciculi from the anterior and poste-
rior surfaces of each lateral portion of the spinal marrow ; so
that each nerve is formed of two fasciculi : one from before,
and the other from behind. The fasciculi are of different sizes
in different parts of the spine. The lowermost of the neck are

MEDULLA SPINALIS.— LIGAMENTUM DENTICULATUM. 395

large and broad; those of the back are slender: and those of
the loins, and upper part of the sacrum, are very large.

The uppermost of the fasciculi of the spine proceed almost at
right-angles with the medulla spinalis, to the foramina through
which they pass : those which are lower pass off in a direction
obliquely downwards ; and the lowermost are almost perpen-
dicular. Between the anterior and posterior fasciculi, a fine
ligamentous chord passes, which is attached above to the dura
mater as it passes through the foramen magnum, and continues
to the OS coccygis. It passes between the tunica arachnoidea
and pia mater, attached to the pia mater by cellular membrane.
It sends off a small process in a lateral direction, to be attached
to the dura mater in the interstices between the places where
the fasciculi pass through the dura mater, and nearly in the
middle between the upper and lower fasciculi.

The spinal marrow terminates in a point near the uppermost
lumbar vertebra. The ligamenta denticulata of the opposite
sides join together at this point, and form a small chord, which,
continuing downwards, is inserted into the os coccygis.

These ligaments may support, and keep fixed, the medulla
and the nerves, as they originate from it.

As the spinal marrow terminates at the upper lumbar verte-
bra the lumbar and sacral nerves go off above: they pass
down like a bunch of straight twigs, and are called Cauda
Equina, from a fancied resemblance to the tail of a horse.
The sheath, formed by the dura mater for the spinal marrow,
continues of its original size, and encloses them in one cavity.

The posterior and anterior fasciculi pass out separately from
the dura mater ; after they are out, the posterior fasciculus
forms a ganglion ; from which one nerve passes that joins the
anterior fasciculus, and thus forms the spinal nerves.

When the nerves go off, either from the spinal canal, or the
cavity of the cranium, the external lamen of the dura mater
where they pass out, attaches itself to the bone or the peri-
osteum ; while an internal lamen, together with the pia mater,
and, perhaps, the tunica arachnoidea, is continued with the
nerve.

396 VEINS OF THE SPINAL MARROW.

This process from the dura mater becomes so much changed,
that it has been considered as cellular membrane.

The pia mater and tunica arachnoidea seem also to invest,
not only the nerve in general, but the fibres of which it is com-
posed. On this account, probably, the nerves are larger after
passing through the dura mater, than they are when they leave
the brain and spinal marrow.

The Arteries of the Spinal Marroiv proceed from the head,
and, with several additions, continue downwards to the lumbar
vertebrae.

There is, generally, one artery on the front surface of the
medulla, which is formed by the union of two branches, that
arise from the vertebral arteries within the cranium. This
artery proceeds downwards and communicates with those of
the neck, and with the intercostal arteries, by the intervertebral
foramina, so that it preserves its size.

It terminates with the spinal marrow ; and the cauda equina
below it, is supplied by branches from the internal iliac, which
enter through the foramina of the sacrum.

There are, generally, two arteries on the posterior surface of
the medulla spinalis, which also pass out from the cranium ;
arising from the vertebral arteries or inferior arteries of the
cerebellum ; they have a serpentine arrangement, and com-
municate with each other, and with the ramifications of the
anterior spinal artery.

All of these arteries are dispersed upon the spinal marrow and
its membrane, and the parts immediately contiguous.

The veins correspond with the ramifications of the arteries ;
but they are collected into two larger branches called the Sinus
Venosi ; which are situated exterior to the dura mater, on the
front and lateral sides of the spinal canal. They extend the
whole length of the canal, and entering the great occipital fora-
men, communicate with the lateral and occipital sinuses.

THE EYE. "^ 397

CHAPTER XIV.

OF THE EYE.

It will be very proper to read the description of the orbit of the eye at page 120,
volume 1st, as an introduction to the following description of the organ.

In addition to that account of the bones, it is to be observed that processes of
the dura mater pass through the foramina optica and lacera, which line the
cavity of the orbit, and unite with the periosteum at the margin of it.

The eye is an optical instrument of a spherical form, which
lies in the orbit, in a bed of cellular membrane, more or less
filled with adeps for the convenience of its motions. Con-
nected with the ball of the eye, are several auxiliary parts
which are calculated for its motion and protection, as well as
accommodation in other respects.

Of the parts auxiliary to the Eye.

Above the upper margin of the orbit, on the prominences of
the OS frontis, called superciliary ridges, the adipose membrane
is commonly more full than it is in the other contiguous places ;
and the skin which covers it is thereby rendered prominent.

The supercilia or eyebrows grow out of this prominent skin.
The hairs which compose them are placed obliquely, with their
roots towards the nose. Their principal use seems to be to
defend the eye from sweat and other matters which roll down
the forehead. They are moved by the corrugator muscle, and
thus express certain passions ; and they are also moved by the
occipito- frontalis and orbicularis palpebrarum.

— The extent and degree of curvature of the eyebrows, differ
much in different individuals. The hairs of which they are
composed, are short, curved, highly elastic, and arranged in
VOL. II. 34

398 THE EYELIDS.

rows, the middle of which are the longest. The internal extre-
mities of the eyebrows, called the head, occasionally meet ; but
most usually, there is an interval between them called glabella,
which presents the smoothness and polish of other parts of the
forehead, and adds to the open and noble expression of the
face. The outer extremity or tail is terminated by a thin
series of hairs, (cauda supercilii) near the outer angle of the
frontal bone. The color corresponds generally with that of
the hair. —

The Eyelids or Palpehra,

Are formed by a slit or orifice in the skin (Jlssura palpebra-
rum) ; immediately under the skin, surrounding this orifice, is
a portion of the orbicularis muscle ; under this portion of the
muscle, there is a plate of cartilage, and under the cartilage, a
portion of tunica conjunctiva, or membrane that covers the
front part of the ball of the eye and lines the eyelids.

— The eyelids, may be considered two movable fleshy cur-
tains, nicely adjusted to one another at their free edges, and to
the anterior surface of the ball of the eye which they exactly
cover.

— They are composed of the skin externally, which is so thin
as to allow the light partially to pass through it, and which is
folded inwards at the free margin of the lids, so as to line their
inner surface, where it takes the character of mucous mem-
brane, (^tunica conjunctiva) ; from the lids, it it reflected again
over the anterior surface of the eyeball, so that the conjunctival
linings of both eyelids form one continuous membrane. The
lids are two in number, upper and lower, palpebra superioris,
palpebra inferioris. They are divided unequally by the trans-
verse fissures ; so that the upper lid is considerably the larger.
Was it not for this, as the motions of the lower lid are very
limited, the eye would be only half uncovered, in what is
called, opening the eye.

— The fissure which separates the lids is not exactly trans-
verse ; it is slightly depressed externally. The reverse is said
to be the case in regard to the Chinese, in whom the peculiar

1^

THE EYELIDS. 399

expression of the eye depends upon the depression of the inter-
nal angle below the level of the outer.

— The cellular tissue of the eyelids is very lax, but comprises
no adipose membrane. Hence the lids may suffer from oedema-
tous or sanguineous effusions, but are never burthened with fat.
The two lids unite at the extremities of the transverse fissure,
and form two angles, or canthi, the internal of which is the
largest, and is called the great canthus. This is owing to the
insertion of the orbicularis at the internal canthus upon a round
tendon, which does not exist at the outer canthus. —

The upper eyelids, therefore, are composed of the skin, of
some fibres of the orbicularis muscle, of the tendon of the leva-
tor palpebrae superioris muscle, of the cartilaginous plate, and
of the tunica conjunctiva. The under eyelid is formed in the
same way, with the exception of the cartilage, which, in it, is
confined to the margin. There is besides no muscle or tendon
in this lid analogous to the levator palpebrse superioris.

These cartilages form the margin of each eyelid, which is
called Tarsus. The upper cartilage is broad in the middle,
and narrow at each extremity, and accommodated to the form
of the eyeball and eyelid. The under cartilage is a narrow
flat rim, which does not extend far from the margin of the eye-
lid. A thin delicate membrane is extended from the upper
and lower margins of the orbit to these cartilages, and has been
considered as forming ligaments for them.

These cartilages are closely connected together by some
fibrous matter* at the external canthus, but terminate short of
each other at the internal, by an attachment to the bifid extre-
mity of the round tendon, in order to allow space for the
lachrymal puncta and ducts. The superior tarsal cartilage, is
much broadest in the middle, where it is about six lines wide.
The inferior is about two lines in breadth, and is nearly of the
same width in its whole extent. Their adhering borders, de-

* This fibrous matter, is part of a thin ligamentous expansion continuous
with the periosteum of the socket, attached to the margin of the tarsal cartilages,
and placed between the conjunctiva and orbicularis muscle. It is sometimes
called ligavientum latum palpebrarum. — p.

400 TARSAL CARTILAGES. TUNICA CONJUNCTIVA.

generate into cellular tissue, by which they are connected to
the fibrous layer of the lids. They present on the inner sur-
face a number of vertical grooves in which are lodged the
glands of Meibomius.

Their edges are formed obliquely, and apply to each other
in such way, that when the lids are closed a groove is formed
between them and the eye ; by which the tears are conveyed
towards the nose.

The use of these cartilages is to keep the eyelids properly
expanded ; and to form margins that apply accurately to each
other.

These cartilages are covered internally by the tunica con-
junctiva.

The levator palpebrae muscle, which arises from the bottom
of the orbit, at the upper part of the foramen opticum, and
passes over the superior muscle of the eyeball, is inserted by
a broad thin tendon or aponeurosis into the cartilage of the
upper eyelid, and draws it upwards, within the upper margin
of the orbit, when the eyelids are opened.

The antagonist muscle to the levator or that vv'hich closes
the lids, is the orbicularis palpebrarum.

The tunica conjunctiva, that lines the eyelids, is continued
from them, without any interruption of the surface, over the
anterior part of the ball of the eye ; in the same manner that
the reflected membranes are continued from one surface to
another.

Although this membrane is a continuation of the skin, it is
essentially different from its structure ; being extremely thin,
flexible, and sensible, and also transparent. It abounds with
vessels, which do not carry red blood in their natural state,
but receive it largely when they are inflamed or much relaxed.
It adheres firmly to the cartilage at the edge of the eyelids ;
and becomes more loose in its adhesion to the lids, as it
proceeds backwards. It is so reflected to the ball of the eye,
that it covers and adheres to about one-third of it anteriorly.
Where it first joins the eye, the adhesion is loose, but this
adhesion becomes firmer as it advances over the eye ; and it
cannot be separated from the cornea without maceration, and

GLAiVDS OF MEIBOMIUS. 401

a slight degree of putrefaction. The part immediately connected
with the cornea is extremely thin and delicate.

This membrane closes the orbit of the eye, and completes
the cavity which contains the muscles, lachrymal gland, &c.,
which are by this means precluded from contact with the exter-
nal air.

— The conjunctiva receives some very delicate nervous fibrils
from the branches of the fifth pair, called the lachrymal and
internal nasal. It contains, there is reason to believe, many
mucous cryptae or follicles, but from their minuteness, it is diffi-
cult to detect them. Stachow, however, asserts that with the
microscope he has seen them most distinctly, though in the pal-
pebral conjunctiva only. According to this observer they are
most numerous in the upper lid, and in the neighborhood. of the
tarsal cartilages ; especially at their extremities.

— He found them in groups of 8, 12, or 15 together, and
sometimes 50 or 60. That portion of the ocular conjunctiva
which covers the sclerotica is sometimes called the tunica
adnata. —

On the inside of each eyelid, apparently between the tunica
conjunctiva and the cartilages, are a number of lines runninc
inwards from the edge of the lid. These lines are of various
lengtlis, from one-fourth to near half an inch ; the longest are
in the middle of the upper lid. Some of them are straight ;
and others are serpentine : their color is a yellowish white.
There are generally more than thirty in the upper eyelid, and
more than twenty in the lower. They are called the glajids
of Meihomius* By pressure a sebaceous substance can be
forced out of them, in the form of fine threads, from orifices
on the edges of the eyelids. They are follicles into which the
sebaceous substance is secreted. This substance appears to
have a two-fold effect : it prevents the tears from running
over the eyelid, as any other unctious matter would do, and

* Charles Etienne demonstrated the little sebaceous glands of the eyelids,
and Casserius caused them to be drawn and engraved a long time before Henry
Meibomius. The latter gave his name to them by a letter printed in Helmstadt
in 1666, in which they were accurately described. See Lassus. — h.

34*

402 EYELASHES. LACRYMAL GLANDS.

it prevents the eyelids from adhering to each other, in conse-
quence of their contact during sleej3.

— The orifices of these glands, are very minute, but will
admit of the introduction of fine bristles. They are disposed
in one or two ranges, immediately behind the eyelashes, and
presenting toward the ball. These orifices lead into the
little lines or ducts, which Meibomius described as glands.
But the gland of Meibomius is now known to be a compound
follicle, or rather a series of minute glands ranged parallel with
each other upon the sides of the duct into which they open ;
some of which communicate together by lateral openings.
The oily matter which they deposit on the edges of the lids,
serves, in the ordinary state of the eye, to confine the tears, as
water is known not to pass so readily over a vessel, the margin
of which is greased.- —

The eyelashes or cilia are placed near the outer edge of the
lower part of the cartilages of each eyelid. They are always
more or less curved, and their convexities are opposed to each
other. By this arrangement the eye is defended from small ex-
ternal objects, and from light to a certain degree, without closing
the lid completely.

— The cilia consists of three or four ranges of hairs irregu-
larly placed, the middle of which are longest, and which gives
to the brush of hairs, a penicillous arrangement. They are
strongest and most numerous in the upper lid. Their bulbs or
follicles are placed between the skin and tarsal cartilages ;* and
of course are not met with in the internal canthus. The lashes,
or cilia are covered by an oily fluid, secreted by a number of
minute cuticular follicles, common round the roots of all hairs.
This secretion tends to keep the hairs separate, and prevents
that agglutination that would otherwise take place, from the dry-
ing of the lachrymal fluid, mixed as it is with the Meibomian
secretion. —

It is necessary, for the perfection of the eye, that the whole

* The tarsal cartilages thus intervene between the bulbs of the cilia and the
Meibomian glands. And upon this is founded Berlinghieri's operation for the
cure of Trichiasis, by the extirpation of the bulbs of the glands. — p.

LACHRYMAL GLAND. 403

surface covered by the tunica conjunctiva, viz. the anterior part
of the eyeball and the internal surfaces of the eyelids, should
be kept perfectly flexible and moist ; for this purpose the lach-
rymal fluid is constantly secreted, in varying quantities, by the
lachrymal gland, formerly called Glandula Innominata.*

This body is -situated in a depression, in the upper surface of
the orbit, near its external margin : it is exterior to, and above,
the tunica conjunctiva. It is of an irregular oblong form, and
rather flat; but it has some .thickness. The under surface is
lobulated, and forms two principal lobes.

From the anterior edge of the gland the excretory ducts, to
the number of six or seven, pass off. They terminate at a short
distance from the gland, near the upper end of the cartilage,
and near the external angle of the eye. They do not commu-
nicate with each other.

These ducts are so small, that they are not often seen by
the naked eye; but there is sometimes a chain of smaller glands,
which lie between the gland and the eyelid, nearly in the direc-
tion of the ducts. — This is called the palpebral portion of the
lachrymal gland, and is of small size.

— The layer or orbital portion of the lachrymal gland, is
about the size of an almond, and consists in a great number of
little fleshy granules of a reddish white color, in which the
extreme branches of the arteries terminate, and from which,
minute excretory ducts are believed to originate. The granules
are separated from each other by processes of cellular tissue,
which are sent in by the general cellular envelop of the gland,
and by nerves and blood-vessels. The excretory ducts originat-
ing from these glandular grains, form by inosculation the ducts
above mentioned, which open through the conjunctiva. The
orifices of these ducts in the conjunctiva, are readily seen in the
eye of bullocks, but in the human eye, cannot well be discovered,
without some artificial preparation.
— After immersing the human eye, for some time in water

* The necessity of this gland, exists only in land and amphibious animals,
in which the eye is exposed to the evaporating effects of the air. In fishes,
Sec, it is not met with. The eyes in them being moistened by the fluid in
which they live. — p.

404 PUNCTA LACHRYMALIA.

colored with indigo, ink, or blood, the orifices become visible,
and the ducts may be filled with mercury up to the gland.
The ducts are three or four lines in length. —

The fluid secreted by this gland, (viz. the tears,) is transpa-
rent, but is always salt to the taste. When evaporated, by
exposure to the air, some cubic crystals, and a small quantity
of mucilaginous matter remain. Chemistry has ascertained that
these crystals contain muriate of soda, and soda uncombined, and
that phosphate of lime and phosphate of soda may be obtained
by burning inspissated tears ; but the whole of the saline matter
does not amount to one-hundredth part of the tears in which
they are dissolved. The tears, therefore, consist of these salts,
and of mucus, dissolved in a large proportion of water.

The tears are carried from the eye by two small canals, which
commence, one on each eyelid, at the internal extremities of the
cartilages, opposite to each other.*

The orifices of these canals, being in small cartilages, (but not
in those called the tarsi,) are always open, and are called the
Puncta Lachrymalia.

Each of these canals run, within the edge of each eyelid,
from the place of its commencement to the lachrymal sac, which
is a larger membranous canal situated in the depression formed
by the anterior portion of the os unguis and the corresponding
portion of the upper maxillary bone ; and extending thence
along the bony canal is the nasal duct, which continues from
this depression into the nose, and terminates under the inferior
spongy bone near its anterior extremity.

These canals are very small at their commencement at the
puncta lachrymalia ; but this small portion is very short ; it
forms an angle with the remainder of the canal, which is con-
siderably larger.f

The canals gradually approach each other as they proceed

towards the lachrymal sac, into which they enter, in contact

with each other, but by distinct orifices.

* The Utile hollow at the internal caathus, in front of the caruncle, and
where the tears collect before entering the puncta, is called the laats Jachry-

malis. — P.

t These canals were known to Galen, and were particularly described by
Fallopius in 1584.— h.

LACHRYMAL SAC AND DUCT. 405

— The orifices in the puncta are sufficiently large to admit
readily a small bristle or probe. The ducts which lead from
the puncta to the lachrymal sac, are called canalicula lach-
rymalia. They are not straight ; they commence by ascend-
ing perpendicularly in the upper, and by descending in the
lower lid, for a line and a half; they are then turned at
a right angle upon themselves, and pursue a course nearly
horizontal to the lachrymal sac. Where the ducts turn
to form the angle, a sensible dilatation takes place, in which are
found one or two minute mucous cryptae,* which sometimes
embarrass the surgeon in operating through the ducts, the end
of the probe or tube becoming entangled in the lower folds. —

About one-fourth part of the lachrymal sac is situated above
the junction of the two eyelids, or the tendon of the orbicu-
laris muscle ; and the remainder below. After it descends
below the orbit of the eye, it contracts and takes the name of
the Lachrymal or Nasal Duct.

— The lachrymal sac is ovoidal in its form, and closed at
top ; it rises about two lines above the round tendon of the
orbicularis muscle, which is immediately in front of it, and
feels like a grain of rice. Its diameter is about equal to that
of a common goosequill. Anteriorly it is covered by the
integuments, the tendon above alluded to, and the orbicularis
muscle. Externally it is bounded by the caruncle, and con-
junctiva.—

The sac and duct have some resemblance to the Schneiderian
membrane in structure ; and are defended with a similar
mucus. The membrane of which they are composed, adheres
to the periosteum of the bony canal.

— Their walls are composed of two membranes, a mucous
and fibrous ; or rather of a mucous facing on a fibrous basis.
The mucous membrane, is internal, contains a number of
follicles, which secrete a lubrifying mucus, as in the urethra,
and as in the latter organ are apt, when inflamed, to produce
strictures or obstructions in the passage, and thus become one
of the causes of fistula lachrymalis.

* Dalrymple, Anat. of Human Eye, p. 277. Lond. 1834. — p.

406 CARUNCULA LACHRYMALIS.

— The length of the nasal duct is from four to six lines ; about
equal to that of the sac. The direction of the duct in its bony
canal, is downwards, backwards, and slightly inwards. At
its termination in the inferior meatus of the nose, (about seven
lines from the root of the nasal process of the u|3per maxillary
bone,) the mucous lining membrane is thrown into a sort of
valvular fold, which sometimes obstructs the introduction of a
probe into it, from the nostril. The swelling of this valve, in
coryza, measles, he, is said to be one of the causes of the
accompanying epiphora. —

The tears appear to enter the puncta lachrymalia upon the
principle of capillary attraction ; and to be propelled forwards
by the motion of the eyelids and the pressure of the orbicularis
muscle.

Between the puncta lachrymalia and the termination of the
eyelids, at their junction with each other, is a small angular
space, which is occupied by a body called the Caruncula
Lachrymalis ; which is of a reddish color, with a few small
hairs growing out of it : it is supposed to be glandular, and to
secrete a sebaceous substance. It has an effect in directing the
tears to the puncta lachrymalia.

— The caruncula lachrymalis, consists of a collection of
small mucous glands — seven in number — substitutes for the
Meibomian glands which are deficient in the internal canthus.
Six of these glands are placed upon a common level, and the
seventh is seated upon the top of the rest near their centre,
making the caruncle conoidal in shape, and about the size of a
grain of wheat.

— The conjunctiva is spread over then), and is pierced by a
number of small apertures, which are the orifices of the excre-
tory tubes of these glands. Each duct is garnished with a
small hair placed close to its orifice. —

Between the caruncula lachrymalis and the cornea, the
tunica conjunctiva, in many persons, forms a plait or fold,
which is very obvious when the eye is directed inwards ;
this has some analogy with the membrana nictitans, or third
eyelid of certain animals, and has been called the Valvula

TENSOR TARSI. 407

Semilunaris ; its principal use appears to be, to give increased
facility of motion to the globe in an outward direction, from the
looseness of its connexions between the lids and the ball.

The muscles of the eye, described at page 304, &tc.. are to
be ranked among the auxiliary appurtenances of that organ.

[At the internal corner of the eyelids is a small muscle which
I had occasion to observe for the first time in the winter of
1821-2. It has, I believe, escaped the notice of other anato-
mists till the present time. This muscle is about three lines
broad and six lines long, and arises from the posterior flat sur-
face of the OS unguis near its junction with the os ethmoides,
and passes forwards and outwards, lying on the posterior face
of the lachrymal ducts. As it approaches the junction of the
lids, it splits into two parts, nearly equal, each of which is
appropriated to a duct, and inserted along its course almost to
the punctum lachrymale.

To get a distinct view of it, the eyelids must be separated
from the eye and turned over the nose, leaving the tendinous
attachment of the orbicularis and ciliaris muscle. The semi-
lunar valve is brought into sight by this process, which must be
dissected away, and also the fat and cellular membrane beneath
it. The muscle is now seen, and by passing bristles through
the lachrymal ducts its connexion with them is rendered evident,
at the same time that we get a good idea of its size, origin and
insertion.

While making this inspection, by turning the muscle a little
aside, we shall be convinced of another fact of some impor-
tance, and which is equally neglected by most anatomists. It
is, that behind the tendon of the orbicularis muscle a ligamen-
tous matter passes from the corners of the eyelids to the flat
part of the os unguis, which ligament would keep the corner
of the eyelids from being deformed, notwithstanding the tendon
of the orbicularis be cut through in the treatment of fistula
lachrymalis. The lachrymal ducts are included in this ligament,
and pass through it into the sac instead of going along the
edges of the eyelids, as is commonly asserted.

This muscle appears to be intended to keep the puncta in

408 THE BALL OF THE EYE.

contact with the ball of the eye. Dr. Physick has suggested,
that it will also keep the edges of the eyelids applied to the
eyeball in cases of extreme emaciation where the eye is
much sunk. While investigating this subject, my attention
was called by Dr. Harlan to a motion prevailing in the puncta
lachrymalia, with which I was before unacquainted. The
puncta project themselves and retract much after the manner of
an earth worm, and it is probable that the latter motion may be
produced in some measure by this muscle.

In consideration of some of the functions of this muscle, I
have ventured to propose that it be called Tensor Tarsi.]*

The tendons of the four recti muscles, being spread upon the
anterior part of the ball of the eye, constitute a partial covering,
which has been called Tunica Albuginea.-f This tendinous
expansion does not extend to the edge of the cornea, but stops
short of it by several lines.|

Of the Ball of the Eye.

The spherical figure of the eyeball depends upon a strong
and firm external coat called the Sclerotica ; which has an
aperture in its anterior part, filled up with a transparent sub-
stance denominated Cornea, that closes it perfectly.

— The antero-posterior diameter of the globe of the eye, is
greater than the transverse. The former is about ten or twelve
lines, the latter about one line less. This difference is owing
to the projection of the cornea, it being a section of a lesser
sphere. A Transverse vertical section of the globe, taken at
any part, will represent a perfect circle. In short-sighted
persons, the antero-posterior diameter of the eye is greater
still, relatively to the transverse. A similar difference exists

* For a more full account of this muscle, see Horner's Anatomy.

f This is no longer considered as a proper membrane ; it is inseparably con-
nected with and forms a part of the sclerotic coat. The partial expansion of
these tendons seen through the conjunctiva, gives a brilliant glistening appear-
ance to the eye, from which is derived the common term, wJate of the eye. — p.

:j: By line, is meant one-twelfth of an inch.

BALL OF THE EYE.

409

between the eyes of young and old persons, and which accounts
in part for the change which time effects in the power of vision.
The axis of the globe of the eye does not correspond with the
axis of the orbit ; but is exactly parallel with that of the ball
of the opposite side, except in cases of obliquity or squinting.
The optic nerves running out in the direction of the axis of the
orbits, must therefore reach the balls of the eyes, on the inner
side of their axis.

Fig. 188.*

— The sclerotic coat forms about five-sixths of the globe of the
eye. The cornea the remaining sixth. —

The sclerotica is lined by a thin and delicate membrane, the
Choroides, which is in close contact with it, but does not extend

* A longitudinal section of the globe of the eye. 1. The sclerotic, thicker
behind than in front. 2. The cornea, received within the anterior margin of
the sclerotic, and connected with it by means of a bevelled edge. 3. The cho-
roid, connected anteriorly with (4) the ciliary ligament, and (5) the ciliary
processes. 6. The iris. 7. The pupil. 8. The third layer of the eye, the
retina, terminating anteriorly by an abrupt border at the commencement of the
ciliary processes. 9. The canal of Petit, which encircles the lens (12) ; the
thin layer in front of this canal is the zonula ciliaris, a prolongation of the
vascular layer of the retina to the lens. 10. The anterior chamber of the eye,
containing the aqueous humor: the lining membrane by which the humor
Ls secreted is represented in the diagram. 11. The posterior chamber. 12.
The lens, more convex behind than before, and enclosed in its proper capsule.
13. The vitreous humor enclosed in the hyaloid membrane, and in cells formed
in its interior by that membrane. 14. A tubular sheath of the hyaloid mem-
brane, which serves for the passage of the artery of the capsule of the lens.
15. The neurilema of the optic nerve. 16. The arteria centralis retinEe, em-
bedded in its centre.

VOL. II. 35

410 TUNICA SCLEROTICA.

over the whole internal surface of the eye, and is deficient in
the whole of the part occupied by the cornea.

On the internal surface of the choroides is spread the pulpy
expansion of the optic nerve, called the Retina; the natural
consistence of which is not much more firm than mucus.

Within these coats is a cavity that corresponds with the
figure of the sclerotica and cornea, but is divided by an incom-
plete membranous partition that separates the anterior part of
it, which is covered by the cornea, from the remainder. This
partition is called h-is ; and it has a circular vacuity in the
centre, directly opposite to the middle of the cornea, which is
denominated the Pupil. Rays of light, which penetrate the
transparent cornea, pass through the pupil into the posterior
part of the eye.

The eye, thus formed, is filled with several transparent sub-
stances, called Humors. The greatest part of the cavity,
posterior to the iris, is occupied by the vitreous humor, which
is thus denominated, from its apparent resemblance to melted
glass.

In front of the vitreous humor, and directly behind the
pupil, is a small body, with double convex surfaces, called the
Crystalline Lens or Crystalline Humor.

In the space between the lens and cornea is a thin fluid, de-
nominated, from its consistency, the Aqueous Humor.

Several of the parts, above enumerated, have exquisite deli-
cacy of structure, and require a very minute description.

Of the Tunica Sclerotica.

The Tunica Sclerotica, or external coat of the ball of the
eye, derives its name from a Greek word, which signifies to
make hard. It is composed of opaque white fibres, of great
firmness, which form a membrane of very close texture, that
supports the globular figure of the eye. It is thicker behind
than it is before ; but the expansion of the tendons of the recti
muscles gives it a' partial additional covering. — At its thickest
part, just at the outer side of the optic nerve, the sclerotica,' is
a line and a half thick. Immediately behind the insertion of

TUNICA SCLEROTICA. 411

the recti muscles, about half a line. The latter is the weakest
part of the parietes of the eye-ball, and a blow applied upon
the cornea will cause a rupture at that part, rather than at any
other. —

It has been considered, by many anatomists, as continued
into the cornea ; but it can be separated from it by putrefac-
tion ; and it is essentially different from it in structure.

The aperture in it, which is occupied by the cornea, is not
perfectly circular, but inclines somewhat to the oval form, the
transverse diameter being rather longer than the vertical.
• Posteriorly it is intimately connected with the optic nerve,
which enters it, not directly at the extremity of the axis that
passes through the centre of the cornea and pupil, but on the
inside of this spot.

The optic nerve has a firm coat (neurilema) which invests it
rather loosely ; this coat seems to be continued into, or expanded
upon the sclerotica. Within it the delicate nerve diminishes
considerably before it perforates the sclerotica, and appears to
be composed of fibres. At the small place of its penetration,
the sclerotica is very thin ; and it seems that the nerve does not
penetrate through one aperture, but these fibres pass separately
through very small foramina, in this thin part. The foramina
are necessarily very small, as the diameter of the whole perfo-
rated portion in some eyes, does not exceed two lines, or
one-sixth of an inch.*

The sclerotica, in its natural state, has few, if any, vessels,
that carry red blood. The great vascularity, which is so evi-
dent in ophthalmia, is in the tunica conjunctiva.

— It is perforated posteriorly immediately around the optic
nerve, with a great number of oblique foramina, through which

* We find one or two of these larger than the rest, for the transmission of
the central artery and vein of the retina. The space occupied by these fora-
mina, is called the lamina cribrosm, or sieve-like plate of the sclerotica. The
optic nerve is made up of bundles of medullary filaments, each of which is
enclosed in a minute envelop of cellular tissue, formed by a process reflected
inwards from the general neurilema of the nerve. By opening the eye, and
removing all the coats but the sclerotic, and then squeezing slightly and press-
ing forward the nerve, in the direction of the ball, the medullary matter will be
seen to exude through the foramina of the cribriform plate. — f .

412 CORNEA.

the ciliary arteries and nerves enter. A little in front of these
are seen other orifices, by which the veins emerge from the
interior ; and near its junction with the cornea, a few openings
are met with, which allow of the entry and exit of vessels, di-
rectly upon the iris. These latter vessels become very apparent
in iritis, but present a hue less intensely bright, than those more
superficial and more serpentine, which are involved in simple
conjunctivitis. — *

The Cornea.

The transparent membrane which fills up the vacuity in th»
anterior part of the sclerotica, is denominated Cornea, from its
resemblance to horn. It is said to be superior in strength to
the sclerotica ; and it is also very firm. It is formed of lamina,
that are separable from each other, which are supposed to be
connected by a very delicate cellular membrane.

This cellular membrane appears sometimes to contain a fluid ;
for, if a section be made of the coats of the eye, and pressure
be applied to the cornea, an exudation will be perceived, both
upon its internal and external surfaces.

— The cornea is composed of six or seven distinct lamella,
laying over each other like the leaves of a book, but which
cannot very readily be separated by maceration. The cellular
tissue which connects them enables us to slide the layers
slightly over one another between the thumb and finger. The
cells of this tissue are filled with a fluid ; hence it has been
called by some writers, substantia spongiosa cornea. This
fluid performs the important office of preserving the trans-

* The neurilema of the optic nerve which is an emanation from the dura
mater of the sl<ull, is lost upon the sclerotic tunic. Hence, Galen, and many
writers since him, even Zinn and Meckel, consider the sclerotic coat as derived
from the dura mater. Many have also described the choroid as derived from
the pia mater. It is better, however, to adopt the opinion of Albinus, Winslow,
and others, that these coats are peculiar and expressly adapted to the eye, and
that the sheath of the optic nerve, is continuous with the sclerotic without
abruptness, by a sort of insensible change, always seen when one membrane
terminates in another. This theory of formation, besides, is not borne out by
comparative anatomy ; for in scaly fish, where the dura mater is membranous,
the sclerotica, is corneous/ or bony. — p.

CORNEA. 413

parency of the cornea, by equably distending the cells. This
may be proved by a simple experiment, viz. by forcing the
fluid by pressure from a part of a recent cornea, when the
portion pressed becomes opaque, but has its transparency
restored by the return of the fluid on the removal of the
pressure. In old persons the cornea becomes denser in its
structure, and usually presents an opaque ring at its circumfer-
ence, called Aixus Senilis. —

The cornea is covered by the tunica conjunctiva, which
adheres firmly to it, but may be separated after maceration. It
can also be separated from the sclerotica after maceration, and
a slight degree of putrefaction, especially if the parts, when in
this situation, are suspended a short time in boiling water.

The cornea is lined internally by a fine serous membrane —
(membrane of Desamet,^ called the Capsule of the aqueous hu-
mor ; which will be evident if the coats of the eye are boiled.
In this case the cornea hardens, and the capsule of the aqueous
humor appears detached from it, like the cuticle raised by
vesication.

In a sound state, the sensibility of the cornea varies consi-
derably.* The vessels in its structure do not carry red blood ;
it is, however, much changed in its structure by inflammation ;
and it is said that blood has been found between its lamina, in
consequence of violent strokes upon the eye.

It is the segment of a smaller sphere than the sclerotica : and
therefore is more convex. The degree of convexity is very
different in different persons ; those in whom it is very great are
necessarily short-sighted. It is not perfectly circular, but rather
oval : the transverse diameter being the longest.

The cornea and sclerotica are connected to each other by
sloping surfaces. The edge of the sclerotica projects over the
internal lamen of the cornea, and the edge of the cornea passes
under the external surface of the sclerotica.

The separation above mentioned proves the cornea and scle-

* It is the opinioa of Dr. Physick, whose numerous and successful operations
on the eye have afforded him many opportunities of judging, that the incision
of the cornea always occasions some pain, which is very different, as to its in-
tensity, in different persons.

35*

414 CORNEA.

rotica to be distinct from each other. And although their
structure is essentially different in the human species, it is much
more so in some fishes and in some birds.

— The cornea is about six lines in its longest or transverse
diameter, and is a section of a spheroid, the diameter of which
would be seven lines and a half. Its thickness is nearly equal
throughout ; varying from a half to the three quarters of a line.
Mr. Ramsden and Sir E. Home assert, that it is rather thickest
in the centre. On the inner face of the cornea, at its junction
with the sclerotica, there is a slight groove, where the iris meets
the ciliary ligament and is attached in contact with it. This is
for the lodgment of a small vein, called the sinus circularis
iridis or canaliculus Fontance, which communicates with the
anterior ciliary veins. Branches from the ciliary nerves have
latterly been traced into the cornea by Schlemm and others.
According to Professors Knox, Cloquet, and Jurine, the most
internal layer of the cornea is united to the iris by short fibres,
which have something of a tendinous appearance, and by which
they think the contraction of the iris, augments the convexity
of the cornea. Professor Jacob considers this internal layer
of the cornea, (placed immediately in front of the lining mem-
brane of the aqueous humor,) as a peculiar layer of semi-
cartilaginous matter, like the capsule of the lens ; the ofiice of
which is to preserve the proper curve of the cornea ; and
which he has named the elastic cornea. He considers it as
terminating behind, by slipping in between the ciliary liga-
ment and sclerotica. It is this membrane, he thinks, which
forms the protruding pouch in ulcerations of the cornea.
Ramsden and Home, assert that the tendons of the recti
muscles are inserted into the layers, or rather expanded over
the surface of the cornea ; by the action of which the cornea
may be flattened. This, however, is but a revival of the opin-
ion of Morgagni and Briggs, which was refuted by Zinn — .

From what has been already stated, it appears that there
are pores in the cornea, through which the fluid situated
between its lamina may be pressed.

It is probable that an exhudation through these pores takes
place after death, as a pellicle then forms on the cornea, which,

THE CHOROID. 415

upon examination, appears to originate from the drying of a
fluid effused there. This has been considered as a proof of
death ; but there are few practical physicians who have not
seen a similar pellicle, during life, in persons who were very
weak.

The Choroid Coat.

The sclerotica and cornea compose a firm external shell for
the eye ; upon which its form depends.

The sclerotica is lined by a thin, flexible, very vascular mem-
brane, denominated Choroides ; which is in contact with it
nearly throughout its whole extent. The choroides has been
supposed to be derived from the pia mater; but this sentiment
is not confirmed by observation ; for the pia mater appears to
be connected with the interior surface of the sclerotica coat.
— The cellular tissue which forms the connection, has been con-
sidered by some an extension of the tunica arachnoidea. Frpm
its being tinged by the pigment of the choroid, it has been called
the memhrana fusca. — The choroid is so delicate a membrane,
and so vascular, that it has been considered by some anatomists
as a texture composed entirely of vessels and nerves. It has
three sets of arteries which are derived from the ophthalmic
branch of the internal carotid, viz.

1st. The long ciliary arteries, which are generally two in
number : they penetrate the sclerotic coat at the posterior part
of the eye, and pass, one on each side of the external surface
of the choroides, dividing at the ciliary circle, each into two
branches, which inosculate with each other around the ereat
circumference of the iris.

— One of the long ciliary arteries (internal inferior) passes
on the inner side, just below the horizontal diameter. The
other (superior external) passes just above this diameter, on the
outer side. It is to avoid this external vessel that, in the usual
operation for cataract, the needle is introduced a little below the
horizontal level of the eye. The only arteries which are attend-
ed by veins, are the two long ciliary. These ciliary veins origi-
nate in the iris. The blood which is conveyed by the short
ciliary arteries is returned by the vense vorticosae. —

416

VESSELS OF THE CHOROID.

Fig. 189.* '^d. The short ciliary arteries,

which are very numerous: they pene-
trate the sclerotic coat near the optic
nerve, are spread upon the choroides,
and anastomose very frequently with
each other : in their progress for-
wards they penetrate from the exter-
nal to the internal surface of the
choroides, and supply the iris and
ciliary processes.
— These are about twenty in number, at the place where
they divide to perforate the sclerotica ; but they originate from
the ophthalmic as three or four separate branches. —

3d. The anterior ciUary arteries, which are not very
numerous, penetrate the sclerotic coat just behind the margin of
the cornea. These are distributed among the branches of the
long ciliary arteries on the iris.

The veins of the choroides are very peculiar : besides those
which accompany the arteries above described, there are seve-
ral veins which are situated more internally than the arteries
and nerves, and about the middle of the eye : their branches
are not arranged in the usual manner, but run from the main
trunk, nearly in a semicircular curve, are almost parallel to
each other, and very numerous ; from this arrangement of their
branches, they are called the Vasa Vorticosa.

— There are, according to Zinn, four or five of these larger
trunks, the branches of which are vorticose, or thrown into
whirls, so as to admit of their arising from the whole surface
of the choroid, in front, and behind, as well as upon the side of
the trunks. This arrangement, has an arborescent appearance,
and has been compared to the weeping willow. The vorticose
vessels, being somewhat like the graceful pendent branches of
the tree. —

* Fig. 189 is a representation of the vessels of the choroid coat and iris.
The long ciliary artery and vein are seen running straight to the iris in front.
The vasa vorticosa are seen upon either side. The short ciliary arteries are
not seen in this figure. —

CILIARY NERVES.

417

— These veins as well as the long ciliary, discharge finally at the
back part of the eye into the ophthalmic veins or sinuses.*
— The arteries that run to the ball are very flexuous and
anastomosing, so that the impetus of the heart may be over-
come, and the retina undisturbed by the pulsation of any of
the vessels. The great vascularity of the choroid appears to
be for the purpose of secreting the pigment in abundance, so
as to absorb the rays of light that enter from the pupil, and cut
off those that penetrate on the side of the semi-opaque sclerotic
coat. —

The nerves which appear on the choroides, come from the
ophthalmic ganglion. They pass very obliquely through the
sclerotica, and run forwards, having a very flat appearance in
proportion to their size : five or six of them are of this descrip-
tion ; some others are very small. There are some filaments
which come from the nasal nerve, without passing through the
ganglion.

The internal surface of this coat is
covered with a black paste, denomi-
nated Pigmentum Nigrum. This
appears to be spread most thickly on
the anterior part of it, and thinner be-
hind, near the optic nerve ; it is said
to be thinner and less dark in old per-
sons. It seems to resemble the matter
of the rete mucosum of negroes, when
that is softened by putrefaction. It is
asserted that the color of this pigment has never been changed by
the ordinary chemical agents, or by moderate heat. When it is
washed away, the internal surface of the choroides appears to
be villous.

There is also a portion of this substance on the external sur-
face of the choroides. It is said that in very recent subjects,
this matter appears to be inherent in the structure of the inter-

* Zinn, De vasis Subtilior Oculi, 1790.

f A representation of the nerves of the choroid coat and the iris.

418 PIGMENTUM NIGRUM.

nal surface, and does not come off when it is rubbed gently ; or
even when immersed in water ; but it is certain, that a consider-
able quantity of it sometimes appears on the exterior surface of
the choroides, in eyes that are not very recent.

— According to some experiments recently made by M. Mon-
dini, and Professor Lavini, ihe dark-brown color of this pigment,
is owing to carbon and oxide of iron ; after incineration, parti-
cles of iron were readily attracted from the remains by the
magnet.*

— In the eyes of many animals — nearly all the ruminantia, the
horse, the cetacea, most of the carnivora, and some cartilaginous
fishes — the choroid presents at its back and lower part, a beauti-
ful brilliant membranous appearance, which is called the tapetiim
lucidum, from its power of reflection. It supplies the place of
pigment ; for underneath it the pigment is nearly or quite defi-
cient. Its color varies in different animals from greenish blue,
to yellow, and silvery white.

— The rays of light in these animals, will therefore make a
double impression upon the retina, as they pass through it to
the choroid and outwards again by reflection. In man this
tapetum does not exist, though the term is sometimes applied
to the inner surface of the choroid. According to Dalrymple,
the membrane of Jacob, is a double reflected serous membrane,
one reflection of which is spread smoothly over the inner sur-
face of the choroid in most animals, and seems to confine the
pigment and prevent its staining the retina, and which, in
maceration, breaks up and carries off" the pigment in shreds.
This appears to be the same membrane described by Mondini,
(^Memhrajia Mondini,) as a magnificent and delicate net-work,
with meshes so fine as to prevent the passage of a single
globule of the pigment to sully in the least degree the delicate
retina. It is now however well known that this inner surface
of the choroid, is formed of a series of cells which enclose the
pigmentary matter. These cells are hexagonal in shape and
form a continuous membrane which under the microscope

* Anatomy of the Eye by J, Dalrymple, London, 1836.

PIGMENTUM NIGRUM. 419

presents a tesselated appearance. The dark brown pigment
wherever deposited in the choroid, the ciliary body or processes,
the back surface of the iris, or even in the skin of the black,
is found lodged in cells of this description ; and where the
coloring is of the deepest hue, the cells will be found in greater
numbers, placed in layers one over another. Ruysch gave a
description of another membrane, since called the Memhrana
Ruyschiana, in which he asserted that he had raised the inner
vascular layer at the back part of the choroid where the final
ramifications of the vessels take place, as a separate membrane ;
anatomists now generally consider this separation to have been
artificial.

— The choroid is still however described as consisting of three
layers — an outer one which is principally made up of the veins
— a middle one consisting chiefly of minute arteries — and an
internal one, the pigmentary lining membrane which includes the
pigment in its cells — .

In the white rabbit, and some other animals, the pigmentum
nigrum is entirely deficient ; and the pupil of the eye appears of
a red color, owing to the blood-vessels of the choroides.*

The general connexion between the choroides and sclerotica
is very slight ; depending upon a fine cellular substance (the mem-
brana fusca before noticed,) and very small blood-vessels and
nerves.

But immediately around the margin of the cornea, the choroides
and sclerotica are firmly connected to each other, by the inter-
vention of a portion of cellular substance, which although soft, is
dense and compact, and of some thickness. As this substance
extends round the circumference of the cornea, it necessarily forms
a ring ; which is between one and two lines broad. This sub-
stance, thus placed, constitutes the Ciliary ligament ; which has,
to the great perplexity of students, been called by many different
names ; as Orbicularis Ciliaris, Annulus gangliformis, &;c.f

It is very distinguishable from the choroides, these lerotica, and

* Its deficiency is also observed in individuals of the human race, called
Albinoes or leuccEthiopics. — p.
f Discovered by Faiiopius in 1584.

420 CILIARY LIGAMENT.

the iris ; and appears generally of a gray color ; but contains the
ciliary nerves and arteries, in great numbers, as they pass to the iris.

In this circular band is a small canal, discovered by the
Abbe Fontana, as mentioned p. 414 ; its use is to lodge a
small venous sinus.*

All the choroides, which is posterior to the ciliary ligament,
is in close contact with the internal surface of the sclerotica ;
but the choroides continues anterior to the ligament ; and this
anterior portion takes a different position. It no longer lines
the internal surface of the shell of the eye ; but is reflected
inwards ; and takes a transverse direction, as if it were to
form a partition. This reflected part forms the ciliary body,
and the ciliary processes, which will soon be described.

The choroides begins to take this reflection inwards, at the
place where it is connected with the ciliary ligament. Imme-
diately anterior to the ligament, the cornea is continued from
the sclerotica, and, being more convex than the sclerotica, it
projects externally and anteriorly. As the ciliary ligament is
situated between the sclerotica and choroides, very near to the
place where the sclerotica unites to the cornea, and where the
choroides is reflected internally to form the ciliary processes,
the edge of the ciliary ligament must lie in the angle formed
by the cornea, which is anterior and external, and the reflec-
tion of the choroides, which is internal. To this edge of the
ciliary ligament is fixed the circumference of the circular
membrane, called Iris, which is now to be described.

The Iris

Is a flat membrane, which does not partake of the spherical
figure of the sclerotica and cornea, or of the choroides, but
extends across a portion of the cavity of the eye, and forms a
septum. As it is circumscribed by the ciliary ligament, it is
necessarily circular. It has a round foramen near its centre,
which is called the Pupil, which, in the healthy subject, varies

* See Fontana on the Poison of the Viper, vol. 2, page 310 ; and also Adolph
Murray, Nova Acta Upsal, vol. 3.

THE IRIS. 421

continually in size, according to the degree of light to which the
eye is exposed.*

The situation of the iris in the cavity of the eye is such,
that, at its circumference, it is nearly in contact with the cir-
cumference of the cornea ; it is actually in contact with the
anterior edge of the ciliary ligament, and with the anterior
surface of that part of the tunica choroides,. which is reflected
inwards, and forms the ciliary processes.

As the iris is flat or plane, and the cornea is the segment of
a sphere, there must be a considerable vacuity between them.
This vacuity constitutes the anterior chamber of the eye.

The iris, therefore, is a septum, passing across the eye at its
anterior part, and separating that portion of the cavity, which
is bounded exteriorly by the cornea, from the larger portion
formed by the sclerotica.

The anterior, or external surface of this membrane, is very
remarkable for its color ; in persons of a light complexion it
is generally of a light blue, intermixed with white ; or of a
gray, or light hazel, &c. In those whose complexions are
dark, it is almost invariably dark also. These colors are so
arranged, that frequently there is an appearance of lines, some-
times nearly radiated, more frequently curved in various direc-
tions, but tending from the circumference towards the pupil or
centre ; and when the general color of the iris is blue, these
lines are often whitish.

When this surface is examined in water with a magnifying
glass, it appears to be covered with very fine villi, which proba-
bly have the effect of increasing its lustre.

From a supposed resemblance of these colors to those of the
rainbow, the membrane has been called Iris, and is generally
known by that name ; but, unfortunately, another appellation
has been given to its internal and posterior surface, which is

* The iris is rather narrower next the nose, than on the side of the temple,
by which reason, the pupil is not exactly in the centre, as first stated by
Winslow in 1711.— p.

VOL. II. 36

422 STRUCTURE OF THE IRIS.

covered with a black pigment like the choroides, and has been
commonly called Uvea.*

This black pigment, on the internal or posterior surface of
the iris, has been supposed to have a great effect in determining
its general color ; and there is some reason for this opinion,
as the iris is partly transparent ; but there is a color inhe-
rent in it, which is most evident when the black pigment is very
carefully washed away.-f

Thus, the light hazel color remains unchanged after the black
pigment is removed ; and it is not probable that light blue is
much influenced by the black pigment.

The iris is capable of dilatation and contraction to a very
considerable degree, by which the pupil, or central vacuity is
enlarged or diminished. By this means it regulates the quantity
of light admitted into the eye. Upon the first exposure to
strong light, the pupil of every healthy person is observed
to be diminished, and upon the diminution of light, to be
enlarged.

It has been ascertained by experiment, that this motion of
the iris is not excited by the action of light immediately upon
it, but on the interior surface of the eye ; and this circumstance
has occasioned the greatest attention to the structure of this
extraordinary and important membrane.

Anatomists of the greatest respectability hold opinions
extremely different, indeed, respecting the structure of the iris.
They agree that there are many radiated fibres on the posterior
surface, commencing at its circumference, which can be readily
seen when the black pigment is washed away ; but while many
respectable anatomists declare that they have not been able to

* So called from its color, which is dark brown, resembling the skin of a
raisin. The inherent color of the iris is either light blue or orange, which, with
the pigment on its back part that varies in thickness and in intensity of die in
difl'erent subjects, form all the variety of colors of the human eye. — p.

f Sometimes the pigment is strewed here and there in patches, thicker than
in other parts, which gives a marbled appearance to the iris. The pigment,
which, like that of the choroid coal, is a secretion from the vessels of the part,
has reflected over it, the serous membrane of the posterior chamber of the
eye. — p.

ACTION OF THE IRIS. 423

see any circular fibres, Dr. Monro describes them minutely,
and has published a plate of them. He considers them as
forming a circle immediately round the pupil, which circle
makes about one-fifth part of the breadth of the iris.*

In the human subject, the iris does not appear to be divisible
into lamina.f It is abundantly supplied with arteries, which
form two circles upon it, and it has also a large supply of nerves.

The operations of the iris, in contracting the pupil, upon
exposure to light, and dilating it, when light is diminished or
withdrawn, have been explained very differently by persons
who have different sentiments respecting its structure. Some
of those persons, who do not believe in the existence of mus-
cular fibres in the iris, suppose its motions to depend upon the
sudden turgescence or depletion of its blood-vessels : while
others impute it to a peculiar quality, exclusively enjoyed by
this membrane.

Dr. Monro, who refers the contraction of the pupil to the
action of the circular fibres, which is excited by the stimulus
of light applied to the retina, considers this operation as analo-
gous to that of the abdominal muscles, in those cases of cough-
ing, which are produced by irritation of the glottis. The
action of the muscles, in these instances, being excited by sub-
stances applied to the glottis, which would have produced no
irritation if they had been applied to the muscles themselves.

The dilatation of the pupil appears, in the human species, if
not in other animals, to depend upon a different cause. It
seems to be a passive state of the eye, which takes place when
the stimulus is withdrawn, and the consequent action ceases.
There is some elasticity of the iris ; and a great many, perhaps
all, of its natural or healthy motions in the human species,
may be explained by the contraction of the circular fibres,

* Si-e his publication, entitled Three Treatises: On the Brain, the Eye, and
the Ear.

f According to H. Cloquet, the iris consists of two lamina, intimately united
near the pupil, but separable towards the greater circumference ; the anterior
layer appears to be composed mainly of the radiating muscular fibres, and the
posterior especially near the pupillary border of the circular or sphincter
muscle. It is, besides, lined, in front and behind with the transparent serous
inembraae of the aqueous chambers. — p.

424 JACOB, ON THE MUSCULAR STRUCTURE OF THE IRIS.

induced by irritation : and by the contraction of the rest of the
membrane in consequence of its elasticity ; which always
exhibits its effects when the muscular action ceases.

The elastic power in this case may have some analogy to
the elasticity of the arteries, which certainly produces some of
the contraction of those vessels; but there is another principle
of contraction superadded to this, which produces effects differ-
ent from those of mere elasticity.*

— It is a question not yet wholly decided, whether the con-
traction and dilatation of the pupil is dependent upon an invo-
luntary sphincter muscle, placed at the pupillary margin, and a
series of longitudinal or radiated fibres, running from the
greater to the lesser circumference of the iris, as asserted by
Monro and more recently still by Professor Maunoir and
others ; or whether it is simply an erectile tissue, dependent
in its contraction upon a rush of blood, under the influence of
some stimulation, into its serpentine vessels. Anatomists of
nearly equal reputation, have advocated these opposite theo-
ries. Small doses of belladonna, stramonium, or opium, dilate
the pupil; larger and poisonous doses, contract it. The
motions of the iris, contracting to diminish the quantity of
light admitted, when Uie rays excite too intense an impression
on the retina, and dilating to receive more when they are
feeble, appear, in many respects, like muscular action, and have
been compared to the heart, dilating to receive blood, and con-
tracting to expel it. We find the pupil after death in a
medium state between dilatation and contraction : if its move-
ments were dependent upon muscular action, this is what we
should expect necessarily to be the result of the relaxation of
the opposing sets of fibres. — Professor Jocob, of Dublin,!
describes the circular muscle as very visible, in some quadru-
peds after the pigment has been removed, on the back surface
of the iris, near the pupillary margin, and that it is about the
twentieth part of an inch in diameter. The longitudinal or

* Some persons, like the late Dr, Wollaston, exercise a voluntary control
over the movements of the iris, dilating or contracting it at will. — p.
t Medico-Chirurgical Transactions.

ORGANISATION OF THE IRIS.

425

Fig, 191.* dilating fibres, he has de-

scribed on the front of the
iris, as consisting of irregular
shaped naasses, placed in the
middle space between the
leater circumference and the
uipil, sending forward a num-
ur of little elevated lines or
ndons which terminate in
iops about the twentieth part
j1 an inch from the pupil, and
from which loops smaller striae
converge to the edge of the
central opening. The whole arrangement, he says, is like that
of the columncB carnece and chord<z tendinea of the heart.
The examination of a hazel eye, in a living subject, or of an
iris, under water, seems in favor of his views. Believing the
iris to be muscular in its structure, I have practised an opera-
tion for the formation of artificial pupil where the iris has no
posterior adhesions, which has in eight cases, resulted in the
most complete success, and was attended with surprisingly-
little irritation. After puncturing the cornea in the usual
method, 1 make an incision of two or three lines near the outer
margin of the iris concentric to the cornea so as to cut off at
their base a number of the radiating fibres. The inner portion
of the iris is next divided at right angles to this incision up to
the closed pupil. Immediately that this is done such action
ensues as seems to indicate the muscularity of the organ. The
inner circle of sphincter fibres divided across, contract, and as
the resistance which the radiated fibres previously made at the
point of division has been removed by their section at the outer
part of the iris, they form at once an oblong artificial pupil,
which is permanently preserved. In several cases this opera-

* Fig. 191, is a v^er)' accurate representation^ according to Professor Jacob,
of the posterior face of the iris, showing the coiumnce cornefe and chordcE
tendinese much magnified. The anterior surface of the iris presents a very
different appearance. — p.

36*

426 ORGANISATION OF THE IRIS.

tion has been unattended with the effusion of a single drop of
blood, and the restoration to sight was immediate.
— The iris is extremely vascular, and receives its blood partly
from the long, and partly from the anterior ciliary arteries.
They anastomose with each other, so as to form the greater
arterial circle round the outer margin of the iris, and then run
out in a serpentine course and from a lesser circle near the
pupillary margin. From this lesser circle, innumerable minute
vessels radiate towards the centre, and abruptly terminate at
the edge of the pupil. When the pupil is contracted to its
minimum size, these vessels become straight. The veins are
also abundant ; some terminate in the long ciliary veins, and
some in the vasa vorticosa.

— With nerves also, the iris is richly furnished, probably more
abundantly than any other tissue of equal size in the whole
economy. It is supplied from the ciliary nerves, which run
out between the choroid and sclerotica in the form of flattened
cords, after they have perforated obliquely the latter tunic.
— They inosculate with each other frequently in the greater
arterial circle of the iris, and appear under the microscope to
form little knots or ganglia ; the branches which they send
inwards towards the pupil, may be seen in some of the larger
quadrupeds to inosculate with each other, but cannot be traced
satisfactorily on account of their faint appearance and pulpy
character. —

In the foetus, prior to the seventh month after conception,
the pupil is closed by a delicate vascular membrane, called
the Membrana Pwpillaris ; which, after this period, com-
pletely disappears.*

— The membrana pupillaris as shown by W. Hunter and
J. Cloquet, consists of two layers, formed by an extension,
back to back, of the serous lining membrane of the anterior
and posterior aqueous chambers, across the pupil. This is
ruptured, or effaced by a retraction of its vessels, so as to

* The discovery of the Membrana Pupillaris is claimed by Wachendorf,
Prof, of Botany in the University of Utrecht ; by John Hunter ; by Haller ;
and by Albinus.

)iii'/.&i

MEMBRA.NA PUPILLARIS. 427

form the lesser arterial circle of the iris,* which is never seen
till after the rupture of the membrane. The lining membranes
of the two chambers then form a continuous coat. —

The iris was formerly supposed to be a continuation of the
choroid coat ; but it is now generally agreed that it is a
distinct membrane ; for when the eye is very slightly affected
by putrefaction, it can be pulled off, and the choroides left
entire.

The choroides, on the contrary, cannot be separated from
the ciliary processes without laceration ; and when the pig-
ment is washed away from its internal surface, it is very
obvious that these processes are continued from the substance
of the choroides and reflected inwards, so as to form a pro-
jection into the cavity of the eye.

Of the Ciliary Body, and the Ciliary Processes.

This internal projection forms a ring or a circle, which has
the ciliary ligament before described, near its circumference,
and anterior to it.f

It is so disposed, that the whole of its internal or posterior
surface appears to be formed into radiated plaits, which extend
from the circumference to the central vacuity, where they
terminate.

The whole of this structure, or the membrane thus plaited,
is called the ciliary body, while the plaits are called the ciliary
processes.

In a natural state of the eye, the ciliary body is covered

* The thickness of the iris, is considered three or four times greater than
that of the thinner portions of the choroid. When the pigment is carefully
wiped away from the posterior surface of the iris, we see a great number of
straight, raised, and converging lines, which are confounded into a membranous
zone near the pupil, formed by the circular fibres. These have some resem-
blance in shape to the ciliarij processes. — p.

f The ciliary ligament or circle, evidently serves as an attaching medium
between the iris, cornea, and sclerotica. Its structure is not fully understood.
Some modern anatomists, have considered it in the light of a nervous gang-
lion ; others as composed of muscular fibres. It forms the inner wall of the
canal of Fontana, described p. 414. Vide, Knox on the Muscularity of the
Ciliary Ligament. Ed. Philos. Trans, vol. x. — p.

428 CILIARY BODY AND CILIARY PROCESSES.

with a large portion of the pigmentum nigrum. It may be seen
very well by placing the eye on the cornea and removing the
posterior part of all the coats, without deranging the humors.
When thus viewed from behind, it has a black surface, and
appears like a ring formed of radiated lines; it has been com-
pared to a flower with radiated petals.

When the black paint is washed off, and the humors of the
eye removed with proper caution, the plaited structure of these
radiated processes will be very apparent ; it then will appear
that the membrane of the choroides is so arranged as to form
radiated plaits, and that these plaits are the ciliary processes.

These plaits or processes do not lie upon each other, but are
placed on their edges, one edge looking into the cavity of the
eye, and the other edge anteriorly towards the iris.

Each ciliary process seems to originate from two lines or
smaller plaits, called the ciliary strice, which soon unite and
form it. The process or plait, thus formed, is rather larger at
its central extremity than at any other part ; and their central
extremities are not of equal lengths, but alternately longer and
shorter.

The ciliary processes do not extend to the centre of the circle
of which they are radii, but stop short of it ; and thus include
a circular vacuity or aperture, which is larger than the pupil of
the iris, and situated a little way within or behind it. This
aperture is occupied by the crystalline lens (to be hereafter
described) ; but the central extremities or terminations of the
ciliary processes do not adhere to the lens, for they are loose
and movable; but they are in contact with its anterior surface,
near the margin.

It is, however, to be observed that the ciliary processes are
loose only at their central extremities ; for, towards their other ex-
tremities, they seem to adhere, anteriorly, to the iris ; and, poste-
riorly, to the retina, and to the capsule of the vitreous humor.

— The ciliary processes vary in number from 70 to 85, and
are divided into the large and small, the latter being included
within the spaces of the former. They are extremely vascular
and when minutely injected and magnified, their vessels present

CILIARY PROCESSES.

429

the appearance of the nervures or vessels of a willow leaf. Their
intimate structure and function are unknown. Home, Wallace*
and others from their observations on the inferior animals, believe
Fig. 1 92.f them to be muscular and to

aid in adjusting the focal
distance of the lens, to the
capsule of which they are
indirectly connected ; draw-
ing it backwards and for-
wards like a magnifying
glass, with 80 strings attach-
ed to its margin. Others,
with equal reason have
believed them to be erec-
tile, altering the posi-
tion of the lens by their
expansion or contraction.
Fishes with spherical lenses, according to Mr. Wallace, have
no ciliary processes ; the adjustment of the lens being in them
effected by a single membrane or muscle attached at one
point: the rolling of the lens, as it is drawn backwards,
it being a sphere, can make no difference in regard to its
functions. —

The ciliary body, (or the radiated ring formed by all the
processes) is about two lines broad in the human subject ; but
the part next to the nose is rather narrower than the rest of it.

The black pigment is spread over the whole of the posterior,
or internal surface of the ciliary body ; but it is much more
abundant towards the circumference than towards the centre.
It is also more abundant in the furrows between the ciliary
processes than it is in the processes themselves ; and as the
membrane, of which the processes or plaits are formed, is of a

* Structure of the eye, by W. C. Wallace. New York, 1536.

t This figure from Zinn's work, represents the corpus ciliare or circle of
ciliary processes in man, on a large scale. In the centre is seen the iris, with
its pupillary opening. There is certainly no direct connexion, between the
central extremities of the ciliary processes and the capsule of the lens. — p.

430 THE RETINA.

whitish color, the processes, at their central extremities, have
a whitish cast.

The black pigment is also spread over the anterior surfaces
of the processes ; on all that part which is loose, and not in
contact with the posterior surface of the iris.

When the pigment is completely washed away, the color
of the ciliary body appears grayish ; but if the eye has been
successfully injected, it will appear to be composed almost
entirely of vessels ; and to have a villous surface.

The Retina.

Within the tunica choroides, and in contact with its internal
surface, is a third coat of the eye, the Retina. This coat is
evidently derived from the optic nerve, although its texture
appears somewhat different.

Before the optic nerve arrives at the ball of the eye, a small
branch of the ophthalmic artery penetrates its coats ; and when
the nerve perforates the tunica sclerotica, as described in page
410, this artery passes with it.

On the internal surface of the choroides, the nerve forms a
small prominence ; and from this, the retina expands, with
many ramifications of the aforesaid artery in it.

The retina has the appearance of mucus, and the semi-
transparency of a surface of ground glass ; but when immersed
in water, it floats like a membrane.

By particular management, when the retina floats in water,
a considerable quantity of the soft substance may be removed,
and a delicate, soft, transparent, membranous substance, with
the vessels, will remain.

The retina, therefore, seems to consist of a delicate, vascular,
membranous web, with a medullary pulpy matter spread upon
it, and supported by it.

Thus constituted, the retina extends from its origin, at the
optic nerve, to the commencement of the ciliary processes.

It lines the choroid coat, and is, therefore, in contact with
the pigmentum nigrum, on its internal surface, but it is simply

THE KETINA. 431

in contact with it, and is not tinged by it. No vessels pass
from it to the choroides : and, when a posterior section of the
eye is made, it slips from it without any appearance of adhesion,
being attached only to the optic nerve.

Most anatomists agree respecting these circumstances, but
there is the greatest difference of opinion respecting the extent
of the retina. Several distinguished anatomists, of the last
century, thought very differently from each other on this sub-
ject ; and two of the first anatomists of the present day have
embraced opinions entirely opposite. Monro is convinced
that it extends under the ciliary processes, to the crystalline
lens: and Soemmering asserts, positively, that it terminates at
the commencement of the ciliary processes.* Some of the
anatomistsf of London incline to the opinion embraced by
Soemmering; and the late ingenious Bichat adopted the opinion
embraced by Monro.

Both parties confide in their own observations, and refer to
the eye. An object which appears so very different to different
persons, who have good sight, cannot be very distinct. The
pulpy substance of the retina appears to terminate at the com-
mencement of the ciliary processes ; but a membrane of a
very different texture seems continued from it to the crystal-
line lens.

Although the eye and the retina have long been objects of
anatomical attention. Professor Soemmering made an inter-
esting discovery respecting it, so lately as the year 1791, viz.
that, at the posterior part of the retina, on the axis of the eye,
and, of course, a little exterior to the entrance of the optic
nerve, there is a spot of a circular or oval figure, about one
line, or rather more, in diameter, of a yellowish or saffron
color, which is brightest about the centre.

In the centre of this spot is a round hole, equal in diameter
to one-fourth of the spot. There are, generally, several small

♦ This opinion of Soemmering, which was advocated by Zinn and Mor-
gagni, and more recently by MecJjel, is now generally admitted. By careful
observation it may be seen terminating a short distance behind the ciliary
body. — p.

•f- See the new CyclopEedia, by Dr. Reese and others, article eye.

432

SPOT OF SOEMMERING.

plaits of the retina about this place ; one of these, which is
very constant, extends from the optic nerve to this spot.

The color of this spot is pale in children, bright in young
persons of mature age, and pale at an advanced period of
life.

The foramen is to be found in the foetus, but not the yellow
spot. The color of the spot diminishes when vision is obstruct-
ed ; and the spot disappears when vision is lost.

Fi^. 193.*

There is the greatest reason to believe that the retina is the
seat of vision ; but it has been ascertained, most decisively,
that the extremity of the optic nerve, from which the retina
originates, is insensible to the rays of light.

— Professor Knox of Edinburg, and J. Dalrymple, from
many careful observations made upon the subject, consider
the folds of Soemmering, as entirely a post mortem appearance,
dependant on a collapsing of the retina, consequent to the
escape of the fluids through the cornea, which takes place
speedily after death. This corresponds with my own observa-

* Fig. 193 represents the retina, to which the optic nerve is attached behind,
expanded in the form of an incomplete sphere over the hyaloid membrane of
the vitreous humor, and terminating in front a short distance from the lens.
The lens is seen lodged with its capsule, in a depression on the front of the
vitreous humor, and surrounded by a series of delicate folds, (zona ciliaris,)
which correspond with the ciliary folds of the choroid, (see fig. 191.) The spot
of Soemmering is seen near the entrance of the optic nerve. — p.

AMMON ON THE SPOT OF SOEMMERING. 433

tion, made upon the eye of a convict within three hours
after execution. In this case the yellow spot of Soemmering
was very manifest, and about two lines in diameter; but the
surface of the retina was perfectly plain, and the foramen
appeared to be but a superficial depression, the size of a small
pin's head, with a slightly elevated brilliant yellow margin.
Dalrymple observed in one case the surface of the retina, per-
fectly smooth, and as the fluid escaped, the circular edges of
the cup-like depression, (which he with Meckel and others,
consider the foramen of Soemmering merely to be,) were elon-
gated, elevated, and finally came in contact, forming the fold of
Soemmering.

— According to Ammon, who has written a work, ex-professo
upon the yellow spot of Soemmering, there is never at any
period of life to be found the foramen of which this author
speaks. The depression on the surface of the retina, and the
appearance of a foramen are owing to the more intimate union
at this point, of the choroid and retina by the intermedium of
vessels. The yellow spot, limhus luteus — according to him,
is very vascular, and is usually apparent fourteen or fifteen
months after birth, and is always to be found in the healthy
adult eye. He has twice sought for it in vain, in cases of
amaurosis, and once in congenital cataract. In the early pe-
riods of foetal life, the choroid is red, and contains no black
pigment.

— After the pigment is deposited, and toward the period of
birth, its color in the axis of the eye, where the yellow spot
is to appear, is of a lighter brown than in other parts. As the
spot begins to make its appearance fourteen or fifteen months
after birth, the yellowness is first obvious on the outer side of
the retina, next to the choroid, and he believes is entirely de-
pendent on the action of light upon the retinal surface of the
choroid pigment.

— The pigment, diluted with water, and exposed to the action
of the rays of the sun, he says assumed a yellowish appearance.
VOL. II. 37

434 ACTION OF THE IRIS.

Inflammation of the eye, he asserts may produce the same
change, as seen especially on the uvea, in inflammation of
the iris around the pupillary margin, where is formed the brown
circle, so commonly attendant on severe iritis. In the early
state of development of the foetal eye, be found the sclerotica
and choroid protuberant inward, opposite the place where is
subsequently formed the yellow spot, at which point penetrate
some of the ciliary arteries that branch from thence into the
retina. The appearance of the black spot or foramen of Soem-
mering, he believes to be caused by a rupture of the delicate
retina at this point, bringing into view the black pigment on
the face of the choroid. In its first stage of formation the retina
appears to be a transparent layer, readily separated both from
the choroid and the optic nerve.

— The use of the yellow spot, which he considers the most
sensitive part of the eye, is to give a common axis to the organ,
and stability during the exercise of vision. Hence the vacilla-
tion of the balls, and occasional squinting common to young
infants prior to the formation of the yellow spot, as well as the
rolling of the balls, in congenital cataract. " Centrum retinae,
in quo macula flava occurrit, prse caeteris ejus partibus lucis
assimilation! optum esse videtur; necessario inde sequitior,
puncretinse locum imprimis lucis radiis offici et quasi detineri,
non potest igitur non uterque oculus uno eodumque dirigi
motu, et uno quasi stabiliri axe. IJJormalis autem haec oculi
conditioni tunc desiderafur, cum macula lutea nondum formata
est, sive cum suspicari licet, hujus organi genesin prohibatum,
aut ejus oeconomiam turbatum esse."*

— In the human eye, the external medullary pulpy layer of the
retina, when beaten up, presents all the appearance of cerebral
matter, a fact first observed by Galen. The nervous matter
is, however, arranged in the form of fibres, agreeably to the
recent microscopical observations of Langenbeck and Trevira-

* Fred. Aug. ab Ammon, de Genesi et usu macnlae luteas, in retina oculi
humani obvise. Accedit tabulae in aes incisa. — Vinariae, 1830.

VASCULARITY OF THE RETINA. 435

nus. According to the latter, when the optic nerve has pene-
trated through the sclerotic and choroid to the retina, its cylin-
ders or nervous tubes spread themselves out on every side,
either singly or in bundles ; each cylinder, or collection of
tubes bending inwards through the vascular layer, and termi-
nating in the form of a papilla on the surface of the vitreous
humor. In the eye of the halibut, the fibrous structure of the
retina appears very manifest.

— Considering the mode of formation of the retina, as described
above, its great sensibility to light, and the known insensi-
bility of the optic nerve to that stimulus if the rays fall on it in
any part of its course without first impinging on the retina, this
tunic cannot be regarded as a mere expansion of the optic
nerve, any more than the nerves themselves can be viewed
as a mere expansion of the brain. It may better be viewed
as a peculiar structure, expressly provided for the purpose of
receiving the impression made by the rays of light ; the nerve
being the mere agent by which this impression is transmitted to
the brain, where it becomes a sensation.

Vascularity of the Retina.

— It receives its supply of blood principally from the arteria
centralis retina of Zinn, a branch of the ophthalmic which en-
ters the optic nerve at a short distance from the ball, and passes
through the central foramen in the cribriform plate of Albinus,
vide p. 410. — Its distribution is principally to the internal vas-
cular layer of the retina, and in the healthy state contains only
the white portion of the blood. The blood is returned in veins
which terminate in a single trunk that passes out through the
cribriform plate. —

[Within three or four years a membrane has been discovered
by Mr. Jacobs, Demonstrator of Anatomy in Trinity College,
Dublin, which is situated between the retina and the tunica
choroidea. Its tenuity and delicacy are extreme. It is dia-
phanous and is thought by its discoverer to be a serous mem-
brane. It extends from the optic nerve as far forwards as the

436

TUNICA JACOBI.

retina goes, and adheres by a delicate filamentous structure to
both the retina and the choroid coat, but much more firmly to
the former. Mr. Jacobs asserts that this filamentous structure,
by which it adheres to the other two coats, is vascular: as this
assertion, however, is founded on a process of reasoning, and
not on absolute demonstration, our assent may very properly
be withheld from it till an injection is brought forward to prove
the fact. This membrane is well marked also in the sheep, ox,
horse, dog, and other domestic animals ; indeed, in all the
mammalia which he has had the opportunity of examining. It
exists, also, in birds and fishes, and is said to be particularly
strong in the latter. M. Cuvier has described it in fish as one
of the lamina of the retina, but its sensible properties are
asserted by Mr. Jacobs to be very dissimilar to those of the
retina.

As this membrane may possibly be confounded by the stu-
dent with one of the lamina of the human retina, it should be
borne in mind that the latter consists of two parts, a pulpy or
nervous expansion and a reticulated vascular structure on
which the pulp is laid, the pulpy part being external.

The reticulated structure is called by some the tunica. vascu-
losa retinae. Most anatomists have known and admitted these
two membranes as composing the retina, yet but few have had
the expertness to separate them from each other, and to leave at
the same time the membranous structure visible. Albinus had
the success to accomplish this separation ; and I am informed,
on the authority of Dr. Physic, that Mr. Hunter also succeeded
in it.

When the common dissection of the retina is made and fixed
in clear water, this membrane will be seen floating around It
in delicate flocculi ; but if a more careful dissection be made,
by fixing the eye to the bottom of a basin of water, by its cor-
nea, through the aid of shoemaker's wax, and the sclerotica
and choroidea be removed from behind, this membrane may
be turned down entire from the retina, with the end of the
handle of a scalpel.]

%

VITREOUS HUMOR. 437

Fig. 194.* — Fig. 194 represents

on the left, the retina,
with a portion of the op-
tic nerve attached to it.
The external membrane
(tunica Jacohi) is turned
down, and the foramen of
'%o^gM?ia^.^^iymjaLiS£as^g:ag^ Soemmering instead' of a

distinct hole, presents the appearance of a fold or depression
with elevated sides. The figure to the right, shows the retina
expanded over the vitreous humor, and the place may be
observed from which the optic nerve has been cut away, and
from which the vessels branch out. To the right of this is seen
the foramen of Soemmering, represented as a black spot, sur-
rounded by a dark shade. —

Of the Humors of the Eye.

The three humors of the eye, viz. the Aqueous, the Crys-
talline, and the Vitreous, are separately invested with a
membranous capsule, which is very delicate, and perfectly
transparent.

The Vitreous Humor

Occupies almost all the cavity of the eye which is posterior
to the iris. It of course possesses a spherical form. It has a
depression in the centre of its anterior surface, in which the
posterior surface of the crystalline lens is received. It is
covered by the retina as far as the retina extends.

The peculiar consistence of this body, which resembles that
of melted glass, is owing to its membrane ; which is a spheri-
cal sac, divided by many septa, or partitions, that form small
irregular cavities, in which a fluid is contained. Tiiis mem-
branous sac is most perfectly transparent, and very flexible ; it
has, however, some strength ; as it will support the weight of
all the fluid it contains, and may be suspended from a hook or
forceps. The fluid may be separated from the membranes,
by beating the vitreous humor in a cup with a spoon : or by
37*

438 CANAL OF PETIT.

suspending the vitreous humor, and then puncturing it. In
either case the fluid escapes ; but tlie internal arrangement of
the membranes is not visible.

It is said that when this body is frozen, the portions of fluid
in the different cavities, have sometimes been distinguishable
from each other, as distinct pieces of ice ; and that their form is
that of small wedges, with their edges directed to the crystalline
lens as a centre, and their bases to the circumference of the
vitreous humor. It is also said, that if this body be immersed
in a solution of potash, the membranes will become opaque,
while the fluid continues transparent ; and that the appearance
of the cells, thus exhibited, agrees with the form of the pieces
of ice above mentioned.

This membrane is now generally called the Tunica Hyaloi-
dea, from two Greek words which imply a resemblance to glass.*

Its particular structure is not perfectly understood. Vessels
are not generally seen on it in the adult; but, in the foetus, the
artery in the optic nerve, (called the central artery of the retina,)
sends a branch through the vitreous humor to the crystalline
lens ; and some branches of this artery are to be seen on the
tunica hyaloidea.f

— The reflection of the hyaloid membrane over this branch of
the artery in its course from behind forwards through the
centre of the vitreous body, forms a passage for the vessel,
called canalis hyaloideus. —

Throughout the greatest part of its extent, it appears to con-
sist of but one lamen ; but at the front part, near the ciliary
processes, there are two lamina. The internal, or posterior,
seems to be a portion of the proper tunica hyaloidea, and
passes behind the crystalline lens. The external, or anterior,
passes over and before the lens ; or at least is attached to the

* Discovered by Fallopius in 1584.

■}■ It is also believed that vessels pass from the ciliary processes of the choroid
to the ciliary folds {zona ciliaris) of the hyaloid tunic, between which the cho-
roid processes are embedded. The hyaloid tunic must be very vascular, though
usually containing only white blood, for in calves and sheep driven with blows
to the shambles, the vitreous humor is often tinged with blood. — p.

CANAL OF PETIT.

439

anterior part of the capsule, in which the lens is contained. It
is supposed, by some anatomists, that this membrane is con-
tinued completely over the crystalline lens ; but it has not been-
separated from it.

As this lamen extends round the crystalline lens, it is in con-
tact with the ciliary processes ; or, with a production from the
retina, which is suppossd by some anatomists to pass between
them. It is impressed with radiated plates by the ciliary pro-
cesses, and some of the pigmentum nigrum of these processes
adheres to it.

As these lamina of the tunica hyaloidea are separated by the
crystalline lens, there is a vacuity between them, around the
margin of the lens, and this vacuity must necessarily be circu-
lar in its course.

It is not probable that any considerable quantity of fluid is
contained in this vacuity ; for the two lamina concerned in its
formation, appear in contact with each other. It can be
readily demonstrated by puncturing the external lamen, and
blowing into it through a small pipe. When thus distended,
there appear to be incomplete partitions in the canal, or partial
adhesions of the lamina forming it, which have the effect of par-
titions ; these partitions are placed in a radiated direction, at
some distance from each other, and give the canal a peculiar
indented appearance. It is called by the name of the celebrated
Petit who discovered it.

The anterior lamen of the tu-
nica hyaloidea, which forms part
of this canal, seems to adhere to
the coats of the ciliary processes ;
for, if a section is made behind
the ciliary ligament of all the
coats of the eye, the vitreous
humor will be found adhering
to the anterior portion of the
section, when it is lifted up.

— Fig. 195, is an enlarged

representation of the canal of

Petit (called godronne, from its resemblance to the puckers or

ornaments of silver plate.) It is here shown inflated with air,

440 ZONA CILIARIS.

SO as to give it the beaded or puckered appearance. The lens
is seen inclosed in its capsule, over which the anterior layer of
the hyaloid is believed to pass. On the outer side is seen the
canal of Petit; and on the outer side of this again, the corona,
or zonula ciliaris of Camper and Zinn, stained by the pigment,
and in the folds of which are placed the ciliary processes.
The two bodies are thus, as it were, dove-tailed together, and
vessels, according to Dr. Knox, pass from the latter to the former.
Fig. 196.* — The zona, or corona ciliaris of

---] Camper and Zinn, may be seen very
distinctly by removing the sclerotica,
choroid, iris, and retina, one or two
days after death, leaving the vitreous
humor entire, with the lens embedded
in its anterior part. We then per-
ceive a number of striae on the vitreous
humor, converging towards the lens,
as seen in fig. 196, corresponding in appearance with the cili-
ary bodies, and narrowed on the inner side exactly as the latter
is. These appearances have been noticed by most wa'iters,
merely as the marks left by the ciliary processes ; but I have
satisfied myself, by a careful microscopical examination of the
eyes of different animals, that it has a real existence, and con-
sists of folds of the vitreous humor, which commence behind
by a well defined margin and terminate in front, by being
attached to the capsule of the lens; the furrows between these
folds being capable of receiving the folds of the ciliary bodies.
By this means, these two bodies are firmly connected or dove-
tailed together, one of which (the choroid) has considerable
strength and firmness, and the other (the hyaloid tunic) is
extremely delicate in structure. By means of this connexion,
the tunic of the vitreous humor and the lens, through the
medium of the ciliary ligament, become attached at the place
of junction of the sclerotic coat and the iris, and without which,
the mechanical construction of the eye would have been imper-
fect.— *

* Vide article Eye, in the Cyclopedia of Anatomy and Physiology, from
■which many of these figures have been taken.

CRYSTALLINE LENS. 441

When the fluid contained in the tunica hyaloidea is discharg-
ed and collected, it appears to resemble, in all its properiies,
the fluid in the anterior chamber of the eye ; which, from its
consistence, has been called the Aqueous Humor. This cir-
cumstance proves that the particular consistence of the vitre-
ous humor is derived from the arrangement of its internal
membranes.

The fluid, thus obtained, consists of water slightly impregnat-
ed ; 1st, with albumen, 2dly, with gelatine, and 3dly, with
muriate of soda.

The vitreous humor appears necessary, to give the ball
of the eye the necessary size, for the performance of its
optical functions ; to keep the retina properly distended, and
to retain the crystalline lens at the proper focal distance from
the retina.

The Crystalline Lens

Is a solid body ; although it is considered as one of the hu-
mors of the eye. It is of a softish consistence, and has been
compared to gum half dissolved ; but is more firm in the cen-
tre than about the circumference.

When sound it is perfectly transparent in young and mid-
dle-aged persons ; but is yellowish in old age. It is convex
on both surfaces, but the convexity of the different surfaces is
different. The anterior surface, which is the least convex, is
the segment of a sphere, whose diameter varies from six to
nine lines. The posterior surface, which is most convex, is the
segment of a sphere, whose diameter varies from four lines and
a half, to five lines and a half. This lens is most convex in
young subjects.

It is invested with a tunic of the same lenticular form with
itself, which has some firmness ; but in a healthy state, is
also perfectly transparent. The lens either does not adhere at
all to the tunic, or so slightly, that it projects from it with
a very slight pressure, as in the operation of extracting the
cataract.

442 CRYSTALLINE LENS.

Fig. 197.* The posterior surface of this tunic

adheres firmly to the tunica hyaloidea,
with which it is in contact : and this
last tnenibrane is generally ruptured in
the attempt to separate them, although the separation can
sometimes be effected without rupture.

The anterior surface is so intimately connected with that
lamen of the hyaloid tunic which passes before it from the
canal of Petit, that it is not separable without laceration ; and
it, therefore, has not been ascertained, whether or not this
lamen extends completely over the surface.

As the capsule of the lens is thus connected with the tunica
hyaloidea, and this last mentioned tunic adheres to the ciliary
body, it necessarily follows that the lens is confined in its
proper position behind the pupil.

Notwithstanding the soft consistence of the exterior portion
of the lens, there is reason to believe that it has a peculiar
organization ; for if it be immersed some time in a diluted solu-
tion of the nitrate or muriate of alumina, or in several other
fluids, and then dried, it will be found to be composed of con-
centric lamellae, which resemble those of the bulbous roots ;
and these lamellae will appear to consist of fibres.

It has been supposed that muscular fibres entered into the
composition of the crystalline lens, but this opinion has never
been generally adopted. f

Between the lens and capsule a small quantity of a trans-
parent fluid is sometimes found, which escapes whenever the
capsule is punctured. This fluid is supposed to be most abun-
dant on the anterior surface, and is called liquor Morgagni.
— The lens, according to Berzelius, consists of a peculiar

* Fig. 197 shows the difference of convexity in the lens at different periods
of life, as represented by Soemmering. To the left is the lens of a foetus. The
middle one is that of a child six years of age ; the right is that of hn adult. The
lens varies in consistence as well as color, as life advances. In infancy it is
soft and pulpy, in youth firmer, so as readily to be crushed between the thumb
and finger — and in old age it becomes tough and firm. Hence the operation
of cutting up the lens for the cure of cataract, is more appropriate in children
than old persons, in whom, from its toughness, it is apt to roll under the needle
and inflict injury on the iris. — p.

t See Dr. Young's Memoirs in the Philosophical Transactions for 1793.

CRYSTALLINE LENS.

443

coagulable albuminous matter, 35.9 — alcoholic extract with
salts, 2.4 — watery extract with traces of salts, 1.3 — membrane
forming the cells, 2.4 — water, 58.0. The liquid contained in
its cells is more concentrated than any other in the body. The
albuminous matter is peculiar, inasmuch as the concentrated
solution instead of becoming a coherent mass on the applica-
tion of heat, becomes granulated, exactly as the coloring
matter of the blood when coagulated, from which it only varies
Fig. 198. in the absence of color;

it differs also from fibrine
in not coagulating spon-
taneously.

— The lens, which at first
sight appears to be a sim-
ple homogeneous body,
more consolidated so as
to form a sort of nucleus
at the centre, is in fact
organized like other parts
of the body. The con-
centric lamellae of which
it is composed are re-
solvable into fibres. The arrangement of these fibres differs
in the different classes of animals ; according to Sir D. Brewster,
in birds and some fishes, as the cod and haddock, the fibres
converge in straight lines, from the two opposite poles of the
spheroidal lens, like the meridians of a globe. In some other
fishes, in reptiles, and a few of the mammalia, the fibres do not
start from a single point, but from two septse at each pole.
The third or more complex structure exists in the mammalia
in general, in which three septa, as in fig. 198, diverge from
each pole of the lens, at angles of 120 degrees ; the septa of
the anterior surface bisecting those of the posterior. The
mode in which these fibres are laterally united, is very inti-
mate— by a sort of reciprocal indentation or rack-work. The
lens in its embryonic development, is formed in three sepa-
rate parts, which are subsequently united at the poles. If the

444

STRUCTURE OF THE CRYSTALLINE LENS.

lens is macerated for a short time in water, or water acidu-
lated with mineral acid, it separates readily from the centre
to the circumference in layers which may readily be reduced
to fibres, as seen in the human lens and in the lens of a fish,
(Lophius piscatorius,) fig. 199.

Fig. 199.* — The opaque structure of the

lens opens at the septae in many
cases of cataract, and presents
the dehiscent appearance seen
occasionally through the trans-
parent capsule. — The fluid call-
ed liquor Morgagni, said to ex-
ist between the capsule and
lens, Professor Jacobs considers a post mortem result, like that of
the pericardium ; the fluid escaping from the cells of the lens.
In the eyes of domestic animals examined shortly after death
no fluid is met with, but if many hours are allowed to elapse,
a small quantity is found in the capsule. My own observations
made both with the naked eye, and with the use of a strong
lens, are in confirmation of his views.

— This distinguished anatomist considers the semicartilaginous
transparent capsule to be applied, immediately on the surface
of the lens, so as to preserve its pulpy exterior in the proper
curvature.

— Between the lens and capsule there is evident connexion at
the back part, where Albinus has injected a vessel passing
from the capsule to the lens. When the anterior part of the
capsule is opened, Mr. J. believes it is the contraction or
shrinking of the capsule which breaks the connexion, and
forces the lens from its bed ; an occurrence which we find
does not always take place in operations upon the eye, without
artificial aid. —

* The small figure to the left in this cut, represents the human lens,
macerated in water containing a few drops of acid for several days, when it is
found split open by fissures extending from its centre to its circumference.
The large figure to the right, is the lens of a fish prepared in the same way by
Mr. Jacobs ; its fibres unfolded with a delicate needle, and presenting a tufted
appearance. — p.

AQUEOUS HUMOR. 445

No blood-vessels are to be seen in any of the humors of
the eye, or their capsules, excepting those of the foetus. In
the fcetus a branch can be traced from the central artery of the
retina, through the vitreous humor, to the posterior surface of
the crystalline capsule, on which it ramifies. In similar sub-
jects vessels have been seen passing from the ciliary processes
to the anterior surface of the capsule ; and it is also asserted by
very respectable anatomists that they have seen vessels passing
from the capsule into the substance of the lens.

The use of the crystalline lens is to concentrate the rays of
light, so as to form a distinct image at the bottom of the eye.

The Aqueous Humor

Occupies the space which is between the crystalline lens and
central extremities of the ciliary processes and the cornea.
This space is divided by the iris into two chambers, very dis-
similar in figure, which communicate with each other by means
of the pupil. The posterior chamber is much smaller than the
anterior, and its existence has been doubted ; but it is easily
proved by freezing the eye, when it is found filled with a part
of the aqueous humor in a state of congelation.

The aqueous humor, in a natural state, is perfectly trans-
parent ; but in the fcetus, and for a short time after birth, it is
reddish and turbid. It consists of water impregnated with
albumen, gelatine, and muriate of soda ; and of course resem-
bles somewhat the fluid of the vitreous humor.

It is probable that this fluid has also a capsule appropriated
to it ; for, after boiling an eye, a delicate membrane can be
found lining the internal surface of the cornea, and extending
from it over the anterior surface of the iris. It has not yet
been traced as far as the pupil, but it is probable that it
extends through the pupil, and lines the posterior chamber
also.*

* This capsule was discovered by Messrs. Demours and Descemet, who dis-
puted each other's claim in 1767. It is thought to be useful in preventing the
cornea from being penetrated by the aqueous humors, and the pigmentum
nigrum from being washed off the iris, and making this humor turbid. M. J.

VOL. II. 38

446

CHAMBERS OF THE AQUEOUS HUMOR.

The aqueous humor is quickly renewed after it has escaped
in consequence of wounds or operations, and blood, accident-
ally effused into this cavity, is often absorbed.*

This fluid preserves the convexity of the cornea, and admits
the free motions of the iris ; allowing, at the same time, a
ready passage to the rays of light.

Fig. 200.f — The annexed enlarged cut from Soem-

mering shows accurately the comparative
size of the two chambers of the aqueous
humor, and how the posterior is formed
by the iris in front, the capsule of the lens
behind, and the ciliary processes with a
small portion of the hyaloid tunic between
these processes and the margin of the cap-
sule, upon the side. The anterior cham-
ber is that formed between the iris and the
posterior face of the cornea,
— Petit has calculated, that the whole
amount of the aqueous humor, does not weigh more than four
or five grains, and that the space between the iris and the cap-
sule of the lens is less than a quarter or half a line ; while
Winslow insisted, that the iris and capsule were in contact in
youth and middle life, when the pupil was contracted.

Certain it is that adhesion takes place readily between them,

and that the posterior chamber is so narrow, that no surgeon can
with any certainty introduce an instrument into it, without the
risk of wounding the vascular ciliary processes, or the iris.

The following are the dimensions and admeasurements

made by Petit and Young, of the different parts of the globe of
the eye.

Cloquet says, that he has traced it in the posterior chamber of the eye. From
this account it appears that there is one capsule, in early foetal life, for the
anterior chamber, and another for the posterior chamber, and that the Mem-
brana Pupillaris is formed by these capsules being stretched across the pupil,
back to back. — h.

* The aqueous humor, according to Mr. Hunter, can be coagulated with
Goulard's Extract.— h.

f Memoirs of French Academy for 1721.

DISSECTION OF THE EYE. 447

Inches.

Length of the optical axis, . . . 0.91

Vertical cord of the cornea, . . . 0.45

Versed sine of the cornea, . . . 0.11

Horizontal cord of the cornea, . . . 0.47

Diameter of pupil as seen through ditto, 0.27 to 0.13

Distance of iris from cornea, . . . 0.11

Distance of iris from anterior surface of lens, 0.02

Radius of anterior surface of lens, . • 0.30

Radius of posterior surface of lens, . . 0.22

Principal focal distance of lens, . . . 1.7.3
Distance of the centre of the optic nerve from the
central fold, (jyellow spot, limhum luteum,) in
the axis of vision, . . . .0.11

Range of eye, or diameter of the field of vision, 1.100

It will be very beneficial to every student of anatomy to dissect this delicate
organ himself, as he will thereby acquire more accurate and precise ideas of its
structure than he can possibly obtain from the ordinary demonstrations.

The eyes of sheep and oxen will serve very well for beginners, as many of
them will be required, and they can be easily obtained. They resemble the
human eye in many respects ; and the circumstances in which they differ may
be readily ascertained by the diligent student ; especially if he dissects the
human eye afterwards.

For this purpose, it will be requisite to have forceps, finely pointed ; with
knives and scissors that are equally delicate in structure ; and also a pair of
strong scissors, bent like those in the cases of pocket instruments.

"When removing the exterior parts, it will be useful to preserve a portion of
the optic nerve, to take hold of.

The dissection of the coats of the eye can be best performed when the eye is
placed in a vessel of water ; which should be shallow or deep, according to the
diflferent stages of dissection.

In some dissections it will be serviceable to form a bed of jelly, to support
the eye, as proposed by Mr. C. Bell.

As the first process in tliis operation, the sclerotic coat can be readily separa-
ted from the choroides, and the cornea with it.

After examining the external surface of the choroides, the ciliary ligament,
and the iris, the iris may be peeled off from the choroides.

The choroides, by a careful process, may then be separated from the retina,
which it leaves surrounding the vitreous humor. The ciliary processes, being
a part of the choroides, come away with it.

The preparation being in water may now be suspended by the optic nerve.
It consists of the vitreous and crystalline humors and the retina. The retina,
originaiing from the optic nerve, adheres anteriorly, also, with so much firm-
ness, that it will support the part enclosed.

448

DISSECTION OF THE EYE.

The retina may be removed without lacerating the tunics of either of the
humors ; and the pjgmentum nigrum, which often adheres to that part of the
vitreous humor which was connected with the ciliary processes, may be washed
away with a piece of soft sponge. By this washing, the radiated grooves in the
vitreous humor, which were connected with the ciliary processes, will be very
apparent.

To examine the iris in its natural situation, an aperture may be made in the
cornea of a fresh eye near its circumference, and the cornea cut out with the
strong scissors. This exposes the anterior surface of the iris.

The iris may then be easily removed, and the crystalline lens, with the cen-
tral extremities of the ciliary processes surrounding it, will be exposed to view.

To examine the ciliary processes on the other side, a lancet may be plunged
into another eye, somewhat anterior to the middle, and the eye divided by
means of the strong scissors. The anterior section should then be laid on the
cornea, and the ciliary process will appear very distinctly, seen through a por-
tion of the vitreous humor. The retina may also be seen at the same time,
and a judgment may be formed of its extent. The view will be more distinct,
if part of the vitreous humor should be cut away with the scissors and forceps,
so as to lessen the quantity without deranging the parts under it.

Several methods have been proposed for rendering the structure of the vitre-
ous humor, and the processes of the tunica hyaloidea, more distinct. None of
them have been very successful : but, if the vitreous humor be suspended in
water by means of a thread passed through that part which surrounds the
crystalline lens, and some large incisions be made into the most depending part
of it, after some days of suspension its bulk will be diminished, by the discharge
of the fluid. If, in this situation, it be immersed in a solution of nitrate of
silver, the tunica hyaloidea will become very apparent ; and, by various degrees
of exposure to light, may have its color varied from a whitish opacity to a dark
brown.

The appearance of the retina is also much changed by immersion in the solu-
tion of nitrate of silver. This eflect of the solution, at first sight, appeared
calculated to decide the question respecting the extent of the retina ; but, after
several applications, it could only be said, that the pulpy substance of the retina
appeared to terminate at the commencement of the ciliary processes, while a
membrane of a different texture seemed continued from it to the crystalline
lens.

THE EAR. 449

CHAPTER XV.

OF THE EAR.

The organ of hearing is composed of three distinct parts, viz.
1. The exterior portion, which, although merely auxiliary, is
denominated the External Ear. 2. A chamber, situated in
the petrous portion of the temporal bone, which is called the
Cavity of the Tympanum. 3. A deeper seated cavity in the
same bone, which, from its complicated form, is denominated
the Labyrinth.

Of the External Ear.

The External Ear consists of the expanded portion, exterior
to the head, commonly called the Ear, and a wide tube passing
from it to the cavity of the tympanum, called Meatus Audito-
rious Externus.

The form of the Ear is so familiar to every one, that it is
not necessary to describe it. The uppermost and longest por-
tion is denominated Pinna. The small pendulous part below is
called Lobus.

The form as well as the firmness of the pinna, depends
entirely upon a cartilage : the lobus consists of skin and cellular
membrane.

The skin which covers the pinna is particularly delicate ;
and, when the cuticle is separated from it by maceration, it
appears to be perforated with an unusual number of foramina,
which are the orifices of the sebaceous glands. It is connected
to the subjacent cartilage by a dense cellular membrane, which,
in most places, is free from adeps.

The cellular membrane of the lobus contains adeps very
delicately arranged.

38*

450 THE EXTERNAL EAR.

The circumference of the ear is formed by a fold of the mar-
gin of the cartilage : and this folded edge is denominated Helix,
from its winding direction. It commences in the cavity called
Concha, to be presently described ; and, after proceeding for-
wards and upwards, it turns round backwards and downwards.

Within this prominent margin is a second prominence, called
the Antihelix, which appears to be formed by a convexity of
the surface of the cartilage, but is found in every ear. It is
nearly semicircular, with its concavity towards the meatus ;
and it forms the margin of the cavity called Concha, above
mentioned. The upper portion of the antihelix consists of the
two superficial ridges, which unite after forming between them
a shallow depression, the Fossa Navicularis or Scapha.

The helix and antihelix form, therefore, three cavities or
depressions, viz. 1. A sulcus, occasioned by the fold of the
helix, which is sometimes called Fossa innorninata. 2. The
Fossa Navicularis ; and 3. The Concha, which may be con-
sidered as the proper orifice of the ear.

Besides these prominences and fossae there are two other
eminences, called Tragus and Antitragus, formed, also, by
this cartilage. The Tragus is anterior to the meatus audito-
rius, and covered by a continuation of the skin of the face.
It projects backwards, so as partly to cover the meatus. On
the inside of it there is commonly a tuft of hair, from which
its name is derived.

The Antitragus is opposite to the tragus, on the posterior
margin of the concha.

On the posterior surface of the ear the convexity of the
concha is very conspicuous.

When the skin and cellular membrane is carefully removed,
and the cartilaginous skeleton of this structure is examined,
its form will not appear so regular as that of the undissected
ear • for there are several deficiencies or vacuities in it ; the
most remarkable of which is between the tragus and the helix.

The cartilage thus formed is attached to the bones of the
face and cranium, by three ligamentous membranes, which
connect it to the zygomatic and the mastoid processes of the

THE EXTERNAL EAR. 451

temporal bone, and to the aponeurosis on the squamous por-
tioq of the same bone.

In addition to the common muscles of the ear, described at
p. 301, vol. i. there are a few muscular fibres, which, m some
subjects, may be discerned on particular parts of the cartilage,
and therefore are considered as muscles proper to these portions
of the ear.

There are five of these portions of fibres ; two on the helix,
one on the tragus, one near the antitragus, and the fifth on the
other side of the ear.

The Major Helicis is on the anterior and most prominent
part of the helix above the tragus. The Minor Helicis is lower
down on the helix in the concha.

The Tragicus lies on the tragus, and the Antitragicus
behind the antitragus, while the Transversus Aaris is on the
other side of the ear, on the prominence formed by the concha
near its circumference.

It may be observed respecting the muscles of the ear, that
eren the common muscles, which are by far the largest, are
unabje, in many persons, to move that organ ; and the proper
muscles, in a large majority of mankind, cannot be perceived to
produce any effect at all.

There are difficulties in explaining the form of the cartilage ;
for, notwithstanding the well-known opinion of the geometri-
cian said to have been employed by Boerhaave, that the line
of reverberation is directed to the meatus auditorius externus
from every part of the ear, in many persons the cartilage is so
situated that the concha appears to be the principal, if not the
only part, from which sound can be reverberated into the
meatus.

It may be questioned whether the backward position of the
ear, which is commonly observed at the present day, is alto-
gether natural ; as a more prominent position seems much
better calculated for the reverberation of sound ; but this posi-
tion of the cartilage is observable in many infants at birth.

It is asserted by some comparative anatomists, that the car-
tilage is stronger and more elastic in proportion to its size, in

452 MEATUS AUDITORItJS EXTERNUS.

man, than In any other animal ; and that the lobus is peculiar
to the human ear.

The Meatus Auditorius Extermis is a tube, extending
from the concha to the membrana tympani, the external
extremity of which is principally composed of cartilage, and
the internal of bone. The cartilage in the external portion of
the tube is a continuation of the substance of the concha. It
does not solely form a complete tube, for, when the meatus is
opened longitudinally and spread out, this cartilage appears
triangular in shape ; a fibrous membrane being joined to it to
complete the tube.

In addition to the deficiency thus arising, there are two others,
one of which, that has a transverse position, is of considerable
size. These deficiencies are called Incisurce ; and the fibrous
structure which closes that which is transverse, has been called
by Santorini, who described it, Musculus Incisurce Majoris.

The cartilage is attached to the bony portion of the meatus
at the lower part of its margin, and forms about one half of the
length of the meatus.

The skin covering the external ear is continued into the
meatus, and lines it throughout ; extending over the incisurae,
and also over the membrana tympani. It adheres more firmly
to the periosteum of the bony part of the meatus than to any
other portion of the canal. Some fine hair is often observa-
ble growing out of it at the external extremity. As the skin
advances deeper in the meatus it becomes more and more
delicate and sensible. The extreme pain excited by the pene-
tration of an insect, or the introduction of an instrument, into
the ear, evinces the great degree of sensibility with which it is
induced.

Exterior to the skin, in the cellular membrane which sur-
rounds it, are many small glands* of a yellowish color, whose
ducts open upon the surface of the meatus, and pour upon it
the substance called cerumen or ear-wax. These glands are
most numerous about the middle of the meatus and at those

* Discovered by Stenon, in 1662. — p.

CAVITY OF THE TYMPANUM. 453

places In which the cartilage is deficient. The cerumen is
fluid at first, and gradually thickens. In some diseases of the
meatus it has the appearance of pus. The use of this secretion
is probably to exclude insects, for which it is well calculated
by its tenacity and bitterness ; and also to defend the delicate
surface upon which it is spread.

The direction of the meatus is inwards and forwards : it is
also curved, with the convexity upwards ; but it is very easy,
by management of the external ear, to admit the rays of the sun
to the bottom of the meatus, and bring the membrana tympani
into view.

— Its length, in the adult, is about ten or twelve lines. It
is a little greater along the inferior part of the meatus, in conse-
quence of the oblique manner in which the canal is closed at its
internal extremity, by the membrana tympani.
— The cerumen is composed, according to Vauquelin, of a fatty
oil, of a peculiar albuminous substance, and yellow coloring
matter. According to Rudolph! and Fourcroy, the bitter prin-
ciple of the cerumen is the same as that of the bile.
— The external ear is a simple acoustic instrument, a sort of
trumpet, for the purpose of catching the sonorous vibrations,
and transmitting them to the membrane of the tympanum, to
which it is connected by the meatus auditorious externus. Its
removal, however, does not appear to impede, very seriously,
the function of hearing, as the rays still find their way down
the meatus. It is not found in purely aquatic animals, but in
those only which hear through the medium of the air. In
some birds, and some reptiles, there are, in front of the tym-
panum, two valves or lips, susceptible of opening and shutting,
like the eyelids. —

A vertical section of the meatus is of the oval figure. In the
foetus the bony part of this duct is not formed, and the meatus
consists entirely of cartilage.

Of the Cavity of the Tympanum.

The meatus auditorius externus is terminated abruptly by
the membrana tympani, which forms a septum that closes it
completely.

454

CAVITY OF THE TYMPANUM.

On the inner side of this septum is the cavity of the Tym-
panum, which may be regarded as the continuation of the bony
meatus.

It differs, however, from the form of this canal ; for its
diameter is greater, and it is not so regularly cylindrical.

It is not deep; as the distance from the membrana tympani,
which constitutes the external side, to the opposite internal
side, is seldom more than three or four lines.

— Its antero-posterior diameter is about six lines, and its
vertical diameter rather more: though from the inequality of
its surface, and its connexion with the mastoid cells and
Eustachian tube, it is difficult to assign its exact dimensions. —

The breadth of the cavity of the tyn)panum is, therefore,
greater than its depth.

It is situated immediately between the membrana tympani,
and the labyrinth which is on the inside of it.

In its natural state this cavity has two apertures ; one of which
communicates with the fauces, by means of the Eustachian
Tube ; and another which leads into the cellular structure of the
mastoid process.

There are also two deficiencies in the bony plate, which
separates it from the labyrinth, called the Foramen Ovale,
and Foramen Rotundum ; but in the natural state of the parts
these deficiencies are closed, and there is no direct conmiunica-
tion of the tympanum either with the labyrinth or the meatus
auditorius externus : the only direct communication being those
above mentioned, with the fauces and the mastoid cells.

That deficiency in the bone between the tympanum, and the
labyrinth, which is called Foramen Ovale, is closed by one of
the small bones of the ear, called the Stapes. The other defi-
ciency, called Foramen Rotundum, is covered by the membrane
which lines the tympanum.

In the cavity of the tympanum are four of the smallest bones
of the body, which are articulated with each other so as to form
one flexible piece. This piece is attached by one end to the
membrana tympani, and the other to the Foramen Ovale; and
it is moved by small muscles connected with it.

»1^A

CAVITY OF THE TYMPANUM. 455

The cavity of the tympanum is lined by a membrane which
has been considered as similar to the periosteum : but it is as-
serted by Bichat that this membrane, when inflamed, resembles
the mucous membranes ; and that in its natural state it secretes
a mucus which passes into the fauces by the Eustachian tube.

This lining membrane is continued over the internal surface
of the membrana tympani, and was supposed by the aforesaid
author to be reflected so as to cover the small bones of the ear.

The opinion of Bichat respecting the nature of the mem-
brane, is rendered probable by analogical reasoning, viz. The
internal surface of the cavity must be in want of mucus or
cuticle, as it is in contact with the air. The membrane is very
sensible in a sound state, and therefore is very different from
periosteum, which it was supposed to resemble.

— The tympanum or middle ear, is but an accessory part of
the organ of hearing, the use of which is to augment and trans-
mit sound received through the medium of the ear. It is found
only in mammalia, birds, and reptiles. The whole organ of
hearing in fishes, consists merely in a membranous bulb, placed
at the exterior, and upon which is ramified the auditory nerve.
— The most simple idea that can be formed of the tympanum,
(as seen in its development in the human foetus and in inferior
animals,) is, that of a cylindrical prolongation of the mucous
membrane of the pharynx, to the front part of the labyrinth,
where it is dilated to form the cavity of the drum, and contract-
ed on the side of the pharynx to form the Eustachian tube. A
bony shell is subsequently formed around the drum, and the
tympanic half of the Eustachian tube. The closure of the
tympanum by bone, is not complete. The membrana tympani
forms part of the wall on the side of the meatus. The internal
wall of the cavity of the tympanum, is formed by the bony
labyrinth. The mucous membrane reflected from the pharynx
into the cavity of the tympanum, is extremely thin, delicate and
very vascular and receives many filaments of nerves. It lines
the whole circumference of the cavity, as well as the mastoid
cells communicating with it, and is reflected over the chain of
bones, and subserves the part of capsular ligament in holding
them together at their place of articulation. —

456 MEMBRANA TYMPANI.

The Membrana Tympani,

Appears to be fixed, in a bony ring in the meatus auditorluSj
and is nearly circular in form. It is not perpendicular to the
meatus, but has an oblique position in it ; the inferior margin
projecting farther inwards than the superior.

The external surface forms a conical concavity, being appa-
rently drawn in by the malleus, one of the small bones of the
ear, to which it is attached.*

It is asserted by several anatomists, that this membrane
may be separated into four lamina, viz. 1. The Cuticle ; and,
2. The Cutis ; which are continued from the skin of the
meatus externus. 3. The proper Membrani Tympani ; and
4. The Lining Membrane of the Tympamim; which is
extended over the internal surface of the membrana tympani.
Notwithstanding these laminae, it is almost transparent in the
living subject when in a healthy state, and appears highly
polished on its external surface, when light is thrown upon it.
It has been injected so as to appear vascular in every part ;
and one or two vessels are sometimes seen even in common
injected preparations. In some cases of inflammation it has
been uniformly red.

It was formerly asserted by Rivinus, a professor at Leipsic,
that there was a natural aperture in this membrane ; but
although this opinion has had several votaries, it is certainly
erroneous. At the same time it is to be observed, that an
aperture occasioned by accident or disease, is sometimes per-
ceived in persons who enjoy the faculty of hearing to a consid-
erable degree. Some persons, thus circumstanced, are accus-
tomed to force tobacco smoke from the mouth through the ears.
It is asserted by a respectable anatomist f that the membrana

* In birds, it is always found convex outwards. This is a universal mark of
distinction in the membrana tympani of birds and mammalia, the two classes
of animals only, in which it exists as a thin vibrating membrane. — p.

f See Mr. Home's Memoir on the structure and uses of the membrana tym-
pani in the Philosophical Transactions for 1800.

EUSTACHIAN TUBE.

457

tympani, when viewed in a microscope, which will magnify
twenty-three times, appears to be supplied with muscular fibres
arranged in a radiated manner. These fibres are on the inter-
nal side of the membrane. He thinks that, under favorable
circumstances, they can be seen with the naked eye.

Fig. 201.*

e""

1i, i,. 9 "'" c'"V e' i

The Eustachian Tube.
The communication between the cavity of the tympanum
and the fauces is formed by the Eustachian Tube, a canal

* Fig. 201, represents a vertical section of" tlie auditory apparatus of the left
side ; the labyrinth being a little enlarged, in order to render its description
more intelligible to the student, a, External ear. b, Lobus of the ear. c.
Antitragus. (/, Concha, the bottom of which is continuous with the meatus
auditorius. e, c, Petrous portion of the temporal bonCj in which the auditory
apparatus is lodged, e'. Mastoid process of the temporal bone, e", Portion of
the glenoid cavity of the temporal bone, in which is articulated the condyle of
the lower maxillary bone, e"', Styloid process of the same bone, e"", Ex-
tremity of the carotid canal, traversed by the internal carotid artery, before it
penetrates into the cavity of the cranium. /, Meatus auditorius externus, g,
Membrana tympani. /«, Cavity of the tympanum, from which the chain of

VOL. II. 39

458 EUSTACHIAN TUBE.

which consists of bone at one extremity, and of cartilage at
the other. It commences in the upper and anterior part of
the cavity of the tympanum, and continues forwards and
inwards through a part of the petrous portion of the temporal
bone, above the fissure in the cavity for receiving the condyle
of the lower jaw. The bony canal terminates in a very
rough and irregular orifice, which is united to a tube com-
posed of cartilage and of membrane, that terminates by a
large orifice behind the inferior turbinated bone of the nose,
and on a line with it.

— The whole length of the Eustachian Tube is nearly two
inches. The bony portion is about eight lines long ; the carti-
laginous from an inch to an inch and a quarter. The latter
rests against the side of the internal pterygoid process of the
sphenoid bone, to the periosteum of which it is attached ; and
on its under surface gives attachment to some of the muscles of
the palate. The course of the tube is nearly horizontal ; it
runs outwards, backwards, and slightly upwards. The open-
ing of the tube into the fauces is funnel-shaped and large
enough to receive the end of the little finger. It contracts sud-
denly, at the place of union of the cartilaginous and bony por-
tion, and it is there barely large enough to admit a good sized
bristle. From this point the calibre of the tube again increases
somewhat in size, in its course to the cavity of the tympanum. —

This tube is lined by a continuation of the membrane of the
posterior nares, which becomes more thin as it proceeds
towards the cavity of the tympanum.

Above the Eustachian Tube, and separated from it by a thin
plate of bone, is a small canal which is nearly parallel to it, and

bones has been removed, i, Two openings leading into the cells of the petrous
portion of the temporal bone. On the internal wall of the cavity of the tympa-
num, are seen two openings, the fenestra ovalis, leading to the Vestibule, I ; and
the fenestra rutunda, leading to the cochlea, n. m, Semicircular canals, k,
Eustachian tube leading from the pharynx to the cavity of the tympanum, o,
Auditory nerve. The protuberance made on the internal wall of the cavity of
the tympanum, is called the promontory. The opening called apertiira cJwrdcB,
and the pyramid, are on the posterior wall of the tympanic cavity, and cannot
be well seen in this figure.

FORAMINA AND PROTUBERANCES OF THE TYMPANUM. 459

continues so to the end of the petrous bone ; this contains the
nternal muscle of the malleus.

The Mastoid Cells.

In the upper and back part of the cavity of the tympanum,
nearly opposite to the orifice of the Eustachian tube, is an
opening which communicates with the cells of the mastoid pro-
cess. These cells do not appear different from those in other
bones, and are lined with a membrane apparently similar.
Their size is proportioned to that of the mastoid process, and
consequently they do not exist in the fcEtus.

— The mastoid cells or sinuses, communicate freely with one
another, and with the cavity of the tympanum, at the posterior
superior part of the latter. The opening into the cavity of the
tympanum is irregular and lodges the short leg of the incus.
The mastoid cells, are analogous in structure to the frontal and
sphenoidal sinuses, which differ entirely from the common
cellular tissue or diploic cavities of bones. The diplce is
placed between the two tables of the bones, whilst the sinuses
have two tables on their exterior, forming vacuities with the
usual compact walls and diploic structure on either side. —

Foramina and Protuberances of the Tympanum.

That part of the surface of the cavity of the tympanum
which is opposite to the membrana tympani, is very irregular,
but it contributes to the formation of several parts which are
very important in the structure of the ear.

When the lining membrane is removed, the aperture called
Foramen Ovale (^fenestra ovalis,) appears in a conspicuous,
situation, rather above the middle of this surface. It would
open directly into the Vestibule, or middle chamber of the
Labyrinth ; but it is closed by the base of the stapes.

Above the foramen ovale is a prominence of the surface, in
which passes the canal for the Fortio Dura of the seventh pair
of nerves.

460 BONES OF THE EAR. MALLEUS. INCUS.

Under the above mentioned foramen is a more striking
protuberance called the Promontory, wiihin which is a part of
the Cochlea, the anterior division of the Labyrinth.

At the under and posterior part of the promontory is the
Foramen Rotundum (^fenestra rotunda,^ which opens into
the Cochlea. This foramen is smaller than the foramen ovale ;
and in its recent state is covered by the membrane which lines
the tympanum.

— Accordino; to M. Ribes,* the membrane closinfr the fenes-
tra rotunda, is a secondary membrane of the tympanum,
formed of three layers ; viz. the linino; membrane of the tym-
panum, the lining membrane of the cochlea, and between them
a peculiar middle membrane ; its structure being like the mem-
brane which closes the bottom of the meatus auditorius externus.
— It is probable that a similar arrangement, exists at the
fenestra ovalis, upon which the stapes rests, though it has
not been satisfactorily demonstrated. The size of both these
fenestrae, is greatly inferior to that of the membrana tym-
pani. —

Behind the foramen ovale is a protuberance w^ith a perfora-
tion in it. This is called the Pyramid. It is excavated, and
contains the muscle of the stapes, which passes out through the
perforation.

The Bones of the Ear.

The four small bones in the cavity of the tympanum are
denominated Malleus, Incus, Orbicularc, and Stapes. (See fig.
202, p. 463.)

The Malleus resembles a crooked club more than any of
the hammers now in use. It consists of an irregular roundish
head, a neck, and a long tapering body, called the Manubrium,
or handle. It has also two processes ; one arising from the
neck, which is long and slender, like a bony fibre, and, there-
fore, called Gracilis. The other, called Brevis, arises from the
upper end of the handle. The handle of the Malleus forms an

* Memoire sur Quelques Parties de I'Oreille Interne.

BONES OF THE EAR. ORBICULARE. STAPES. 461

angle with its body, the salient side of the angle presenting
outwards ; the space from this angle to the termination of the
manubrium, or in other words the whole manubrium is con-
nected with the membrana tympani.

The Incus resembles a molar tooth, with two roots, widely
separated from each other. On the body is a depression which
is connected with the head of the malleus. One of the roots
or crura is much longer than the other.

The Os Orhiculare is equal in size to a small grain of sand.
It is connected to the extremity of the long crus of the incus,
and to the upper part of the stapes.

The Stapes has a strong resemblance to the common stirrup.
The upper part is called its head, the lower part its base, and
the two lateral portions its. crura. One of the crura is longer
than the other. A groove is also observed on the inner side of
its crura, when they are examined with a microscope. The
base is applied to the Foramen Ovale.

The situation of these bones is such that the head of the
malleus and the body of the incus are in the upper and anterior
part of the cavity of the tympanum, which extends above the
membrana tympani. The malleus is the most anterior of
the two bones : its manubrium projects downwards, and is
included between the internal lamen of the membrana tym-
pani and the membrane itself. Its long process extends hori-
zontally inwards and forwards, into the fissure of the glenoid
cavity.

The incus is so placed that the depression on its body re-
ceives the head of the malleus. The shortest leg projects
backwards horizontally, and is attached by a ligament to a
point in the opening into the mastoid cells. While the long
leg projects downwards like the handle of the malleus, but
behind it, and at a small distance inwards from the membrana
tympani.

The situation of the stapes is almost at right angles with the
long leg of the incus, projecting inwards. Between the head
of the stapes and the long leg of the incus, the os orhiculare
intervenes.

39*

.,.i^JibS^jbit^Y:^2^iifSAt

462 MUSCLES OF THE BONES OF THE EAR.

When these bones are viewed in their natural position, the
short leg of the incus projects horizontally backwards, the
long process of the malleus horizontally forwards; the han-
dle of the malleus, and the long leg of the incus, directly down-
wards, one connected with the membrana tympani, and the
other with the foramen ovale, by the intervention of the orbi-
culare and stapes.*

The Muscles of the Bones of the Ear.

The aforesaid bones appear to be regularly articulated for
motion with each other, and they are furnished with several
muscles.

One of these muscles runs in the bony canal above the Eus-
tachian tube, and is inserted into the posterior side of the
handle of the malleus, below the root of the long process. Its
effect is to draw in the malleus, and membrana tympani. It
is therefore called Tensor Tympani, or Internus Auris.

Another muscle, as it is supposed to be, runs in the fissure
on the outside of the Eustachian tube, and is inserted into the
long process of the malleus.

This is supposed to draw the malleus obliquely forward, and
of course to relax the tympanum. It is therefore called Lax-
ator Tympani, or Externus Mallei; but there are the strong-
est doubts respecting the muscularity of this organ.

Morgagni, Haller, Lieutaud, and Meckel, could not satisfy
themselves that it was muscular ; and Sabatier also doubts it ;
while Bell, Fyfe, Hume, Bichat and Gavard, appear to adopt
the opinion of its muscularity.

Some anatomists describe a third muscle of the malleus as

arising from the superior posterior margin of the meatus audi-

* Lassus, in his excellent discourse on Anatomy, informs us that Fallopius
and Eustachius described nearly the whole interior of the ear. The most
ancient authors had remarked the thin transparent membrane which closes the
extremity of the meatus externus. Fallopius describes particularly the tympa-
num ; of the four bones within it, the malleus, incus, os orbiculare, and stapes,
Berenger de Carpi described the two first ; Ingrasias, Eustachius, Columbus, and
Louis Collada, a Spanish physician, disputed the discovery of the fourth with
each other ; and Vesling assures us that Francis de la Boe, a Dutch physi-
cian, discovered the third, which is the smallest. — h.

iiiii

CHORDA TYMPANI. 463

torius, where the membrana tympani adheres to it, and uniting
to the neck of the malleus. It is supposed to draw the malleus
and membrana tympani upwards and forwards. This, how-
ever, is noticed by few authors. (It is called the Laxator
Tympani minor.)

The stapes is also supplied with one muscle called the Sta-
pedius, which lies in the cavity of the pyramid. Its tendon
passes through the foramen in that protuberance, and is inserted
into the posterior part of the head of the stapes. It pulls the
head of the stapes upwards and backwards.

Fig. 202.* — Breschet, in an admirable

ff ^ paper on the organ of hear-

\ / ing, after very careful researches

on the subject, admits but
two muscles to the chain of
bones, the tensor tympani or
internus auris, and the sta pe-

'^^^^43i*'^/%^^'"'-*"^ ^''•'^' which he calls laxator

tympani. In birds, there is but

- \ -" '/one muscle attached to the

I \ \ chain of bones, and that is a

I \ tensor of the tympanum. In

^ 6 C ■& reptiles, even when the chain of

bones was met with, Breschet was unable to discover a

single muscle. —

The Chorda Tympani.

In the upper and posterior part of the cavity of the tym-
panum is a small nervous chord which enters by a foramen

* Fig. 202, is a magnifiecl representation of the cavity of the tympanum,
and its chain of bones, a, a, Cavity of the tympanum, b, Membrani tym-
pani. c, Manubrium of the malleus, the end of which is attached to the mid-
dle of the membrani tympani. d, Head of the malleus articulated with the
incus, e, Processus gracilis, arising below the neck of the malleus, and extend-
ed into the glenoidal fissure of the temporal bone ^ upon its extremity is inserted
the laxator tympani muscle of the malleus, if it really exist. /, Tensor tym-
pani muscle, g, Incus, the horizontal short leg of which is placed in the cavity
leading to the mastoid cells, the long vertical leg of which is articulated with
the OS orbiculare, h. i, Stapes, the top of which is articulated with the os orbi-
culare, and the base rests upon the membrane, closing the fenestra ovalis.
k, Stapedius muscle. —

464 CHORDA TYMPANI.

near the basis of the pyramid, and passing downwards and
forwards, goes out at an aperture in the fissure of the cavity
for the head of the lower jaw. In this course it crosses the
long leg of the incus, and the manubrium of the malleus,
and passes between them, being in contact with the manu-
brium.

This nerve comes off from the portio dura immediately
before it emerges from the foramen stylo-mastoideum, and
after passing a short distance through a small canal, enters the
cavity of the tympanum as above described. After passing
out of the cavity of the tympanum, it joins the lingual branch
of ihe fifth pair of nerves.

It was believed by the late Mr. John Hunter, that the chorda
tympani is not simply a branch of the portio dura, but that
it is the twig of the reflected branch of the spheno-palatine
nerve, which, entering the os petrosum by the Vidian Fora-
men, joins the portio dura ; and after passing with it a consider-
able distance, leaves it at the place above described.*

There is the greatest reason to believe that the principal object of the structure
above described, is to transmit to the labyrinth those impulses of the air
which occasion sound. The membrana tympani, with the small bones and
their muscular appendages, seem to be the agents for this purpose. The
Eustachian tube and the mastoid cells are subservient parts. The effect of
the chorda tympani in the cavity has not been ascertained.

With this view of the subject, it is surprising that persons, in whom the mem-
brana tympani has been destroyed, should enjoy the sense of hearing in a
very considerable degree of perfection. Such, however, is the fact.

It is necessary thai there should be a communication between the cavity of the
tympanum and the exiernal air, in order that the function may be duly per-
formed.

This is evinced by the deafness which results from the obstruction of the Eus-
tachian tube, and the cure of this deafness by relieving that obstruction ; as
well as by the salutary effects of opening the membrana tympani ■,-\ and even
of instituting a communication through the mastoid cells, in cases where the
obstruction of the Eustachian could not be removed.

It has been supposed that the Eustachian tube has the effect of transmitting sound
to the ear, and particularly the voice of the individual of whose structure it is a
part ; and it is certain that we hear our voices very distinctly, (although pecu-
liarly modified,) when the external orifices of the ears are closed : but the well-

* I have followed Mr. H. in this dissection, and have no doubt of his opinion being cor-
rect.— H.

t See Dr. Sim's paper on this subject, in the first volume of Memoirs of the Medical
Society of London ; and Astley Cooper's in the London Philosophical Transactions.

THE BONY LABYRINTH. 465

known fact, that a small watch, when placed in the month, and not in coniact
with any part of it, is scarcely heard, if heard at all, renders this opinion very
doubtful. It ought, however, to be remembered, during the investigation of
this subject, that persons who hear with difficulty are almost invariably in
the habit of opening their mouths when they listen.

Of the Lahyrinth.

Those parts of the organ of hearing which have been ah-eady
described, seem calculated for concentrating the vibrations of
air; and for communicating, with some modification, the motion
they occasion, to the Lahyrinth.

This important portion of the ear consists of three very dis-
similar parts, which communicate with each other, and form one
general cavity.

The central part of the cavity is a chamber, of a form which
approaches to the oval, and has been compared to that of a
grain of barley. It is called the Vestibule.

At one extremity of this chamber (the posterior) are three
tubes, each of which is curved so as to form a large portion of a
circle. These tubes communicate with the vestibule, by each
extremity ; but they form only five orifices, because two of their
extremities are united before they open into the vestibule.
These tubes are denominated the Semicircular Canals.

At the other extremity of the vestibule is a conical tube con-
voluted like the shell of a snail. This is called the Cochlea.
It also conmnunicates with the vestibule.

The Ldhyrinth, thus complicated in its form, is situated on
the inner side of the cavity of the tympanum. Its position is
such, that the Vestibule, and the Cochlea are opposite to the
Membrana Tympani and the Semicircular Canals are posterior
to it. , The apex of the cochlea is on the side of the labyrinth
which is next to the tympanum ; the basis of the cochlea is
next to the brain.

The texture of the bone which immediately surrounds these
cavities is much harder than that of the other parts of the os
petrosum ; and if the bone of a foetus be used, these softer parts
may be cut away so as to leave behind the bony substance

466 VESTIBULE. COCHLEA.

which surrounds these cavities, corresponding exactly to their
form.

The Lnhyrinth, when thus prepared, may be considered as
a solid body which has been enveloped in a softer substance,
and is brought into view by detaching the soft substance,
which surrounded it.

In the foetus it is nearly as large as in the adult, so that the
structure of the ear can be investigated with great advantage
in such subjects.

The Vestibule

Is situated within the Foramen Ovale. There are two
remarkable depressions of its internal surface ; one, which is
in the superior part, is called Semi-eliptical ; the other, which
is below, has the name of Hemispherical.

When the dried preparation is examined, there are several
foramina in this cavity, viz. the Foramen Ovale, already men-
tioned, a round aperture, by which it communicates with
one of the cavities of the cochlea, and the five openings of the
semicircular canals. Besides these, there are several small
perforations from the Meatus Auditorius Internus for the
transmission of nerves.

The Cochlea

Commences at the anterior part of the vestibule. It is a
conical tube, so convoluted that it has the form of the shell of
a snail making two circuits and a half round a centre.

It may be considered as wound in a spiral direction round a
pillar of bone. To this central pillar the name of Modiolus is
applied. It commences at the Cavity called Meatus Auditorius
Internus ; and at its base is somewhat excavated. It gradually
diminishes in diameter as it proceeds towards the apex of the
cochlea, and is, therefore, conical in form ; but it does not pre-
serve this form to its termination, for near the apex it gradu-
ally becomes broader, and thus forms a second cone inverted.

LAMINA SPIRALIS AND SCALA OF THE COCHLEA. 467

This last portion of the central pillar is called the Infundihu-
lum. It is hollow ; and the portion of bone which covers its
cavity, constitutes the basis of the inverted cone and the apex
of the cochlea. It is called the Cupola.

The tube thus wound round the modiolus, or the cochlea, is
divided from the beginning to the end by a partition.

The cavities are called Scala, and the partition Lamina
Spiralis.

The Lamina Spiralis is made up of four parallel strips,
which compose its breadth.

1st. A plate of bone.

2d. Outside of this, a softer plate, which appears cartila-
ginous.

3d. A cellular portion, which appears to contain a pellucid
fluid.

4th. A thin membranous strip, which completes the septum
or partition.

These parts may be distinguished from each other, when
magnifying glasses of sufficient power are used.

The bony plate is composed of two lamina with small can-
celli between them, in which are canals for the transmission of
the fibres of nerves. These canals are extended into the carti-
laginous part.

The membranous part which completes the septum is con-
tinued into the lining membrane on the surface of the cochlea.

The bony portion of the scala does not extend towards the
apex of the cochlea so far as the cartilaginous and membranous
portions ; and none of them continue to the apex, for the lamina
spiralis terminates in the infundibulum before it has arrived at
the apex. Its extremity has the form of a hook, and is, there-
fore, termed Hamulus.

As this septum does not extend to the apex of the cochlea,
the two scalae necessarily communicate with each other at the
apex.

These different bands or strips which compose the lamina
spiralis, are called its Zones, and are termed Zona Ossea, Zona
Coriacea, Zona Vesicularis, and Zona Membranacea.

468 THE THREE SEMICIRCULAR CANALS.

From what has been stated it follows that there are two
cavities of the cochlea, each of which continues throughout its
whole extent. One begins at the vestibule ; the other at the
tympanum. But a membrane extended over the foramen
rotundum separates this last from the tympanum. They com-
municate with each other at their terminations. From their
origins they are denominated Scala Vestibuli and Scala
Tympani.

As both the cochlea and the vestibule are filled with a fluid,
it is evident that a vibration produced on the membrane of the
foramen rotundum may be communicated through the two
scalse to the vestibule.

The three Semicircular Canals

Are placed obliquely behind the vestibule. Their position
is such that one is Superior, another Posterior, and the third
Exterior. The superior and posterior are so placed that one
extremity of each may be considered as internal and the other
external. They unite at their internal extremities, which
therefore form but one orifice in the vestibule. Their other
extremities, being separated to a considerable distance, form
each one orifice ; while the external canal, which is smaller
than the others, opens by two orifices.

Each of these canals is nearly of the same diameter, viz.
rather more than two lines.

At one of their extremities, each one of them has an enlarge-
ment, which is called Ampulla ; and there is no other variation
of their diameters.

The cavity of the labyrinth, thus complicated, is perforated
by many small foramina, through which various nerves are
transmitted.

These foramina communicate with the large canal on the
posterior side of the petrous bone, called Meatus Auditorius
Internus ; which continues very near to the basis of the cochlea,
and transmits the seventh pair of nerves.

The bottom of this cavity is divided by a lidge into two
unequal fossae ; the uppermost of which is the least.

.,4^L\-';. Ji^iiitlj;

MEMBRANOUS LABYRINTH. 469

In the tipper Fossa are two foramina ; the anterior, which
is the largest, serves to transmit the Portio dura, a part of the
seventh pair, to be hereafter described, which passes through
the petrous bone to the face. The posterior foramen forms a
pit with a cribriform bottom, which admits nervous fibrillae to
the vestibule.

The anterior part of the Inferior Fossa is also cribriform ; its
perforations lead to the cochlea ; one of them, which passes
through the modiolus to the infundibulum, is larger than the
rest. The posterior part of this fossa is occupied by foramina,
which pass to the vestibule and semicircular canals ; but they
are not so numerous as those which lead to the cochlea.

' Contents of the Labyrinth.

This interesting cavity is lined throughout by a delicate
membrane. It contains sacs and tubes, and a plexus of deli-
cate nerves, which constitute a soft labyrinth within that which
is composed of bone.

In the cavity of the Vestibule are two sacs distinct from each
other, and also from the lining membrane.

One of these denominated Sacculus Sphericus, or Sacculus
Vestibuli, is situated partly in the Hemispherical Cavity of
the vestibule, and has no direct communication with any other
part.

It contains a limpid fluid, and is said to have so much firm-
ness, that when opened with the point of a lancet, it will retain
its form.

The other sac is situated partly in the depression called
Semi-elliptical, nearly opposite to the foramen ovale : it is so
transparent that it is sometimes seen with difficulty, and appears
like a bubble of air in a fluid. All the membranous semicircu-
lar canals, which are soon to be described, communicate with
it by each of their extremities: it has been called Alveus Com-
munis by Scarpa, and Utriculus by Soemmering.

In the bony canals already described, are three Membra-
nous Semicircular Canals, which resemble them in form.
VOL. II. 40

470 COCHLEA.

They have an ampulla at one extremity, as they arise from the
sac above mentioned, and are cylindrical during the remainder
of their course ; they are transparent, and have smaller diame"
ters than the bony canals, although they are rather longer.

The Auditory Nerve.

Upon this structure, viz. the Sacs in the Vestibule, the Mem-
branous Tubes in the Semicircular Canals, and the Lamina
Spiralis of the Cochlea, are expanded the fibres of the Audi-
tory Nerve.

This nerve, with the Portio Dura, and its appendage, the
Portio Media, composes the seventh pair of nerves of the
brain.

It is called Portio Mollis, and is very distinct from the Portio
Dura, although they pass together along the Meatus Audito-
rius Internus.

Corresponding to the foramina and the cribriform structure
of the bottom of the meatus auditorius internus, the Auditory
Nerve passes into the labyrinth in branches, or fibrillae, of
various sizes. One portion of them enters the vestibule, and
has been traced upon the alveus or utriculus, and its internal
surface; and also upon the semicircular membranous tubes.
Another portion seems exclusively appropriated to a part of
these tubes. And a third is spent upon the sacculus sphericus.

These nervous fibres seem to terminate in a pulpy expansion
on the internal surface of the aforesaid sacs and canals, in a
way which has some analogy with the termination of the
optic nerve.

A large bundle of these fibrillae enters the cochlea at its
base ; and the largest of them passes through a foramen,
mentioned before, along the centre of the modiolus to the
infundibulum.

These fibrillae divide most minutely, and passing between
the plates of the Lamina Spiralis, as well as the other parts
of the bony structure of the cochlea, at length form a plexus,
which has the appearance of a pulpy membrane, that is

COCHLEA.

471

extended over the whole of the lamina spiralis. Thus is the
auditory nerve distributed.

— The central portion of the modiolus, which contains a
great number of minute canals, was called by Scarpa the tractus
spiralis foraminulosus. The nerves of the cochlea enter these
canals and pass out successively at right angles between the
two bony plates forming the zona ossea of the lamina spiralis,
to be expanded on the membranous portion of the lamina.
The nervous pulp is expanded in a naked state, and the neurile-
ma which it throws off, forms, according to Breschet, the basis
of the membranous structure of the lamina spiralis. —

Fig. 203.*

To complete the account of the labyrinth, it is to be observed
that a pellucid fluid certainly exists in it, exterior to the sacs

* Fig. 203, is a vertical section of the cochlea made through lis axis in
order to exhibit its internal structure, much magnified, a a a, Branch of the
auditory nerve to the cochlea {nervus cochharis), over which the veins are seen
running and penetrating in small branches through the lamina spiralis. The
arteries are not shown here, but they have the same course as the veins, b,
Filaments of the nerve, lodged in the zona ossea of the cochlea, c c, Anasto-
moses of the filaments of the nerve with one another in the form of loops, in
the zona media, d, The neiirilema abandoning the nervous loops, in order to
iosm, according to Breschet, the zona membranosa. The blood-vessels are

472 COCHLEA.

in the vestibule, and to the membranous semicircular canals ;
so that the membranous labyrinth may be said to be immersed
in a fluid.

This fluid fills, also the cochlea.

— A useful distinction has been made by many anatomists
of the parts of the labyrinth or internal ear, into a bony laby-
rinth and a membranous labyrinth. The bony labyrinth,
consisting of the bony vestibule, cochlea, and semicircular
canals, forms only the frame-work or walls to more important
parts. The sacs of the vestibule, the membranous lining of the
cochlea, and the membranous semicircular tubes, are the parts
upon which the auditory nerves and vessels are distributed, and
form the structures immediately concerned in the production of
hearing. The membranous cochlea, so far at least as has yet
been observed, lines the internal face of the scala of the bony
cochlea, and appears to serve as its periosteum as well as a
field for the expansion of the cochlear division of the auditory
nerve. The vestibule and the semicircular canals have a perios-
teal lining membrane distinct from their membranous structure
and from which the limpid fluid of the labyrinth is secreted.
The membranous sac of the vestibule, and the membranous
canals, occupy but a small part of their respective bony cavi-
ties, with the walls of which, according to the recent researches
of Breschet, they are only indirectly connected by the nerves
and blood-vessels which enter their structure through foramina
in the bony labyrinth. The limpid fluid alluded to, (p. 410,)
called the lymph of Cotunnius, from the anatomist who first
described it, is found not only filling the cavities of the mem-
branous labyrinth, but likewise fills up completely the space
between the membranous and bony vestibule, and the mem-
seen accompanying all these branches, e, A venous sinus, excavated in the
bone, at the outer margin of the zona memhranosa. The venus sinus e, opens at
the margin of the lamina spiralis, which divides the scala tympani below from
the scala vestibuli above. Between the windings of the double tube, which
resemble the turns of a circular pair of stairs, is seen a process of bony mat-
ter passing in to the modiolus. The bristle is passed in at the infundibulum,
through the scala tympani, and brought out through the scala vestibuli, show-
ing the communication of these cavities. —

ENDOLTMPH. PERILYMPH. 473

branous and bony canals. It is asserted by Brugnone and
Ribes, that the lymph but partly fills the cavity in its natural
condition ; but Breschet,* from elaborate researches in man and
a variety of vertebrated animals, declares this to be an error.f
The membranous structure is afloat as it were in this fluid,
and is affected by the slightest impulse communicated to the
fluid, through the membrane closing the foramen rotundum
and foramen ovale, with which the fluid is in contact. The
fluid of the membranous labyrinth is denser in fish than in land
animals. M. E. Barruel has examined it chemically in the
great seal, (Squalus Cat. L.) He found it viscous and transpa-
rent, containing a matter floating in it, which when dried formed
a calcareous powder.

— For the sake of clearness of description, Breschet proposes
to call the fluid within the men)branous labyrinth the endo-
hjmph ; that between it and the bony labyrinth the perilymph.
The auditory nerves terminate in delicate villi, which project
in the cavities filled by the endolymph ; and in order to give
the sonorous impulse transmitted from without more effect
upon the nerves, there is placed in the cavity of the labyrinth
from one to three calcareous substances which are thrown into
agitation by the impulse. These have been long known to
exist in the ears of osseous fishes, as small concretions of car-
bonate of lime, see fig. 203, called otoliths ;J and Breschet has
found them invariably in the state of granular powder which
he calls otoconie,\\ in man, the three upper classes of verte-
brated animals, and in cartilaginous fishes. The cavity in
which the perilymph is contained in the cochlea, vestibule
and semicircular canals, is continuous, so that an impulse
transmitted through the membrane of the foramen rotundum,
would pass along the scala tympani across the infundibulum,

* Recherches Anatomiques et Pathologiques sur 1' Organs de 1' Ouie et sur
1' Audition, dans 1' Homme et les Animaiix Vertebras ; par G. Breschet. Me-
moires de 1' Academie Royale de Medecine ; torn. v.

-f- Cotugno and P. F. Meckel held the same opinions as Breschet.

^ OCj, cjToj, ear ; Xi9oj, stone. 0 Orof, «()*•(£, sw/jj, powder, dust, etc.

40*

474

CALCAREOUS CONCRETIONS IN THE LABYRINTH.

down the scala vestlbuli, and be felt both in the vestibulum

and semicircular canals. In
the same manner the action
of the chain of bones upon
the foramen ovale, would
be felt through the entire
labyrinth.

— It has been suggested that
'^ the two foramina, (ovale
and rotundum,) are provid-
ed for the purpose of render-
ing more complete the trans-
mission of the vibration of
the membrana tympani.
One is acted on by the
chain of bones, the other
by the air of the tympanic
cavity; both' at the same
time causing movements in

* Fig. 204, is a magnified view of the bony labyrinth of the right side of
the body, with the membranous labyrinth (consisting of semicircular tubes,
median or utricular sinus sometimes called saccuhis ellipticus and saccttlus spheri-
cus,) pulverulent concretions, and the termination of the nerves. The two scala
of the cochlea are also seen, as well as their openings into the vestibule and
into the cavity of the tympanum. The bony labyrinth is represented as cut
open, showing the membranous labyrinth. All the parts marked with the
asterisks (**) are filled with the lymph of Cotunnius. a, Ampulla of the
anterior or semicircular canal, b, Ampulla of the internal semicircular canal.
c. Ampulla of the posterior semicircular canal, d, Anterior membranous semi-
circular canal, e, External membranous semicircular canal. /, Posterior
membranous semicircular canal, g, Common membranous canal resulting
from the junction of the anterior and posterior canals, d and/, h, Place where
the semicircular canal opens into the utricular or median sinus, i, i, Utricular
or median sinus, filling a greater part of the vestibule, and exhibiting through
its walls a mass of calcareous powder at h, (otoconie utriculaire.) I, /, Sac
containing also a mass of calcareous powder at OT, {otocotiie saccvlaire.) w, Ner-
vous fasciculus, forming an expansion, o, on the ampulla of the anterior canal;
another,^, on that of the external ; and a third, q, on the sinus utriculosus. r,
Nervous fasciculus distributed on the sac. v, Nervous fasciculus distributed
on the posterior ampulla, s, s, Lamina spiralis, s, End of the lamina, form-
ing its hamulus or hook, t, Commencement of the scala tympani near the
fenestra rotunda, which is not shown here, u, Commencement of the scala
vestlbuli. X, Modiolus or column, round which is wound the lamina spiralis.

CALCAREOUS CONCRETIONS IN THE LABYRINTH. 475

the lymph, at opposite points in the labyrinth, which should
pass once through different portions of the labyrinth, agitate
all the parts on which the nerves are spread, and finally neu-
tralise each other in the semicircular canals and in the scala of
the cochlea, so as to prevent the repetition and reverberation
of single sounds.

— The calcareous concretions above alluded to, are found, in
the mammiferae, only in the alveus communis and sacculus
ellipticus of Scarpa, in which the semicircular tubes open, and
which Breschet calls the middle sinus. They form a small
single granular mass. Opposite these concretions the auditory
nervous filaments terminate in great number, and the promi-
nent villi which they form seem even to reach the concretions.
— Gregoire St. Hilaire and Breschet, have instituted compari-
sons between the parts of the labyrinth which form the organ
of hearing proper, and the parts contained in the globe of the
eye. The endolymph they call the vitrine auditive, and con-
sider it functionally analogous to the vitreous humor of the eye,
in allowing the sonorous rays or impulses to pass through it, and
in keeping distended the membranous labyrinth upon which the
nerves terminate, and which they consider analogous to the
retina. The light calcareous concretions are, as they think, for
the purpose of increasing the effect of the impulses, as the cry-
stalline humor increases the effect of the luminous rays by con-
centrating them into a focus. Arnold and Tiedemann consider
the membrana tympani as analogous in its office to the iris, regu-
lating, by its state of tension or relaxation, the degree of impres-
sion made upon the nerves of hearing. This comparison is ren-
dered more complete, by the recent discovery by Arnold, of an
auricular ganglion, which is considered as an appendage of the
sympathetic nervous system, and which, according to them, is
as much the central regulator of the sympathetic or instinctive
movements of the membrana tympani, as the ophthalmic gang-
lion is of that of the iris.

ij, y, Bristle lodged in the infundibulum {Helicotrome,) by which the two scala
communicate together at the top of the modiolus, z, Place where the modio-
lus is continuous at its summit, with the walls of the osseous labyrinth, w, w,
w, Membranous portion of the lamina spiralis. —

476 jacobson's nervous anastomosis.

0/ Jacobson's Anastomosis,^ or the Nervous Plexus of the
Tt/mpanum and the Auricular Ganglion of Arnold.

— The cavity of the tympanum receives nerves from various
sources, which communicate together upon the walls of that
cavity so as to form a plexus, and which are chiefly spent upon
the parts situated in the tympanic cavity.

— This plexus is formed by branches from the great sympa-
thetic, the glosso-pharyngeal, the trigeminal or fifth pair, the
facial, the auricular ganglion, and the pneumogastric.
— This plexus, see fig. 205, is found on the outside of the walls
of the cranium, and on the outer face of the inner wall of the
cavity of the tympanum. It is observed in all animals endowed
with a tympanum : and in fishes that possess only an auditory
bulb, formed by the labyrinth, it is found spread in a few fila-
ments on the outer face of the bulb, the usual situation of the
tympanum in other animals.

— Shortly after the glosso-pharyngeal nerve emerges from the
jugular fossa, it forms a gangliform enlargement, called the
ganglion of Andersch, from the anatomist who first described
it, or s^angUon petrosum, from its proximity to the petrous
bone. From this ganglion passes, upwards and forwards, the
nerve of Jacobson, and enters a small canal, the orifice of
which opens in the excavated border, which separates the
carotid canal from the jugular sinus. The nerve emerges
from the canal near the anterior border of the fenestra rotunda,
traverses the promontory, comes in front of the foramen ovale,
passes below the anterior part of the tensor tympani muscle,
and curves forward between this muscle and the Vidian nerve,
to terminate in the auricular ganglion of Arnold.
In the latter part -of its course it is parallel with the proper

* The existence of this plexus was first made known by M. Jacohson, of
Copenhagen, who traced an anastomosing loop from the glosso-pharyngeal
nerve through the cavity of the tympanum, which there left branches, and
thence was reflected downwards to' join the third branch of the fifth pair.
Since then, the nerve has been shown to terminate, or arise in a ganglion, dis-
covered by Arnold of Zurich, on the lower surface of the third branch of the
fifth pair of nerves, called auricular ganglion, ganglion oticum, ganglion maxillo-
tympanique, — P.

AURICULAR OR OTIC GANGLION OF ARNOLD.

477

nerve of the tensor tympani muscle, which comes off from
this ganghon.

Fig. 205.*

— This is the usual method of describing the course of this
nerve, but we might, according to Breschet, with equal pro-
priety adopt the views of Arnold, and consider it as arising
from the ganglion which is evidently the fact in regard to
many of the inferior animals, as the nerve is larger near the
ganglion, than in the tympanic cavity. As it enters the tym-
panum, it gives off one filament to the fenestra rotunda and

* Fig. 205 exhibits a view of the auricular ganglion of Arnold and its connex-
ions with surrounding parts. A, Right side of the cranium. B, Petrous portion
of the temporal bone. C, Cribriform plate of the ethmoid bone. D, Turbinated
bone. £, Carotid artery. P, Internal jugular vein, a, Auricular ganglion or
ganglion of Arnold, sending off its branches to the tympanum, to the soft palate,
and its descending twigs of communication, b, Ganglion of Meckel, or spheno-
palatine ganglion, c, Ganglion of Gasser, or semilunar ganglion of the fifth pair
of nerves, rf, Opthalmic nerve, e, Superior maxillary nerve. /, Inferior max-
illary nerve. ^, Chorda tympani. /;, Malleus, j, Incus. /;, Glosso-pharyngeal
nerve. I, Ganglion formed on this nerve, called ganglion of Andersch ox ganglion
petrosum. m, m, Branches from it through the tympanum to the auricular gang-
lion called Jacobson's Anastomosis, n, Branches of communication between
this nerve, and the carotid plexus and ganglion, o. — p.

478 AURICULAR OR OTIC GANGLION.

the raucous membrane surrounding it, and another to the
membrane surrounding the margin of the foramen ovale.
Whilst in the bony structure of the promontory it gives off
several filaments tlirough canals in the bone ; viz. several
filaments of communication pass through the osseous wall of
the carotid canal to unite with the carotid plexus of the sym-
pathetic ; others form a junction with the vidian or chorda
tympani nerve. A filament from the pneumogastric (the
tympanic) anastomoses with it, either before or after its entry
into the cavity of the tympanum. A filament is sent off from it
in the direction of the Eustachian tube, and another branch is
occasionally met with, between this nerve and the portio
dura, which Breschet is disposed to think is continuous with
the pars media of the seventh pair of nerves. Many minute
blood-vessels accompany these branches. See fig. 205.
— The auricular ganglion of Arnold, is small, though more
than double the size of the ophthalmic, and is ash-colored and
pulpy like those of the sympathetic nerve. It is situated in
advance of the ganglion of Gasser, on the lower surface of
the inferior maxillary nerve at the inner margin of the fora-
men ovale of the sphenoid bone. The existence of this
ganglion may readily be detected by any one skilled in minute
dissection.

— It is united by short nervous roots, and cellular tissue to
the third branch of the fifth pair of nerves. Besides the
branches mentioned as coming from the auricular ganglion,
Arnold, Breschet, and others, describe branches of communi-
cation which pass from it ; one to the superior cervical ganglion
of the sympathetic along the tract of the arteria meningea
magna, one which passes into the internal auditory meatus to
anastomose with the auditory nerve, as well as other branches
which unite with filaments of the fifth and facial nerves. I
have not as yet been able to trace these filaments with entire
satisfaction, and those who have attempted to follow minute
nervous fibrils through bony parts can well appreciate the
difficulties of the undertaking. The German anatomists in
general, consider this ganglion, as well as the ophthalmic,

THE AQUEDUCTS.— COURSE OF THE PORTIO DURA. 479

spheno-palatine, submaxillary, and naso-palatine, as so many
appendages or cranial terminations of the sympathetic nerve. —

The Aqueducts.

It is, probably, on account of this fluid, that two small canals
exist ; which are called, after the anatomist who first suggested
their use, the Aqueducts of Cotunnius.*

One of these commences in the scala tympani of the cochlea,
near the foramen ovale ; and terminates in the jugular fossa,
by a small orifice, situated before the spine that separates the
eighth pair of nerves from the internal jugular vein. It is
called the Aqueduct of the Cochlea.

The other originates in the vestibule, under the common
orifice of the two canals, and terminates on the posterior sur-
face of the petrous bone, by a small orifice, which is situated
at some distance behind the meatus auditorius internus. It is
called the Aqueduct of the Vestibule.

— The aqueducts of the cochlea and vestibule are large in
the foetus and during the growing period of the bone ; and as
Itard has first observed, become in old age extremely minute
and often entirely obliterated. The external orifice of the
aqueduct of the vestibule corresponds to a venous sinus (sinus
petrosum,) and that of the cochlea to the internal jugular
veins. The researches of Brugnone and Ribes have shown
conclusively that the aqueducts are simple foramina for the
introduction of veins. —

To this account of the ear it ought to be added, that the
Portio Dura, after entering into the petrous bone by the fora-
men in the upper fossa of the meatus auditorius internus, pro-
ceeds in a canal which is called the Aqueduct of FaUopius,
through the bone, to the foramen stylo-raastoideum, on its
inferior surface, where it emerges, and is distributed to the face.
It is therefore called the Facial Nerve by some anatomists.

In the course of this nerve from the meatus through the solid
bone, it forms a remarkable angle, and then passes between the

* See Sandiford's Thesaurus Dissertationum, &c., vol. i.

480 FUNCTIONS OF DIFFERENT PARTS OF THE LABYRINTH.

cochlea and the semicircular canals, to the foramen stylo-
mastoideum.

In this course it soon receives the Vidian nerve already
mentioned; and it sends off the chorda tympani, immediately
before it passes out at the foramen stylo-mastoideum. It also
sends off small fibrils to the muscles of the bones of the ear.

It has not been ascertained whether the portio dura, the Vi-
dian nerve, and the chorda tympani, have any effect upon the
function of hearing.

The situation of those branches of the auditory nerve which are expanded in
the vestibule and the semicircular canals, is somewhat different from the sit-
uation of those which are in the cochlea ; but it has not yet been ascertained
how far their functions are different.

The information on this subject derived from comparative anatomy, is very
interesting; but, for want of more acquaintance with the state of this func-
tion, in the different animals, no very decisive inferences have been drawn
from it.

The vestibule and semicircular canals occur much more frequently than the
cochlea, which is to be found in few animals, if any, besides those of the
classes of mammalia and of birds. It is therefore supposed necessary to
that perfect state of hearing which the animals of these classes enjoy. But
there remains a considerable difficulty on this subject ; the cochlea is not, by
any means, so perfect in birds as in quadrupeds ; yet many birds appear to
have clear perceptions of musical sounds, and some birds imitate articulate
sounds with considerable accuracy.

That the impression which produces hearing is made on the nervous expansions
in the Labyrinth, does not appear to be doubted by any one. The structure
of the whole organ, and the analogy between it and the eye induce a strong
belief that this is the case.

This belief is confirmed by a dissection recorded by Mr. Haighton,* in which
Original Deafness was found to depend upon a quantity of cheese-like matter,
which filled the whole labyrinth, and was attended with a considerable
diminution of the size of the auditory nerve, while all the other parts of the
organ were in a perfectly natural state.

* See Memoirs of the Medical Society of London, vol. 3.

PART XI.
OF THE NERVES

The nerves are those whitish cords which pass from the
brain and spinal marrow to the various parts of the body.

A general account of their origin is contained in the descrip-
tion of the basis of the brain and of the spinal marrow,* which
may be considered as introductory to the present subject.

The nerves, in general, appear to be bundles or fasciculi of
small cords, each of which is composed of a series of fibres
that are still smaller. These fibres consist of medullary mat-
ter, which is derived from the brain and spinal marrow, and
is enclosed in a membranous sheath that appears to arise from
the pia mater. The smaller the fibre, the more delicate is the
membrane which invests it.

As the nerves proceed from the brain and spinal marrow,
through the foramina of the cranium and the spine, they are
enclosed in a sheath formed by the dura mater ; but when
they arrive at the exterior extremities of the foramina in those
bones, this coat, derived from the dura mater, appears to sepa-
rate into two lamina. The exterior lamen combines with the
periosteum, and the interior continues to invest the nerve, but
seems to change immediately into cellular substance; so that
the exterior coat of the nerves may be regarded as composed
of cellular membrane, which is continued from the sheath
derived from the dura mater.

It has been supposed that the membrane which forms the
sheaths for the medullary fibrils of which the nerves are com-
posed, is of a peculiar nature ; but it appears to be derived from

* See volume ii. p. 389.
VOL. II. 41

482 GENERAL STRUCTURE OF NERVES.

the pia mater, investing the brain and the spinal marrow. It
is very vascular.*

The ramification of a nerve is simply the separation of some
fibres from the general fasciculus. The branch commonly forms
an acute angle with the main trunk.

The course of these branches from their origin to their ter-
mination is generally as straight as possible.

When the nervous chords are examined in an animal
recently dead, there is an appearance of white lines arranged
in a transverse or spiral direction. The cause of this appear-
ance is not well understood.

In various parts of the body networks are formed by the
combination of different nerves or the branches of nerves. In
those instances the branches of one nerve unite with those of
another, and form new branches. These new branches again
divide, and their ramifications unite with other new ramifi-
cations to form other new trunks. These new trunks divide
again, and form new combinations in the same way.

The trunks last formed proceed to the different parts of the
body, as other nerves do which arise immediately from the brain.

These combinations are denominated Plexuses. There are
several of them in the cavities of the abdomen and thorax,
formed by the ramifications of the par vagum and the sym-
pathetic nerves. The four lower cervical, and the first dorsal
nerve, form a very remarkable plexus of this kind, which
extends from the side of the neck to the axilla, and forms the
nerves of the arm. The lumbar nerves form a similar plexus,
although not so complex, from which the crural nerve arises.
The anterior nerves of the sacrum also unite for the formation of
the great sciatic nerve.

It appears to be clearly ascertained, that the great object of
this peculiar arrangement is the combination of nervous fibres
from many different sources, in each of the nerves, which are

* Several authors have written professedly on the strncture of the nerves,
viz. Monro, in his " Observations on the Structure and Functions of the Nerv-
ous System."— Bichat, "Anatomie Generale." — Fontaaa, "Treatise on the
Poison of the Viper." — Reil, " Exercitationes Anatomicce."— Scarpa, " Annota-
tiones Academics." — Prochaska, " De Structura Nervorum."

I regret that it has not been in my power to procure Reil, Prochaska, or Scarpa.

STRUCTURE OF NERVES. 483

distributed to any organ. Thus, the smaller nerves of the
arm, that are distributed to the different parts, are not to be
regarded simply as branches of any one of the five nerves which
are appropriated to the upper extremity, but as composed of
fibres which are derived from each of them.

Many of the nerves are enlarged in particular places, so as to
form small circumscribed tumors, which are denominated
Ganglions.

These Ganglions are generally of a reddish color. By
very dexterous management, they can be shown to consist of
a texture of fibres. The larger cords which compose the
nerve, seem suddenly to be resolved into the small fibres, of
which they consist. These small fibres, after proceeding sepa-
rately a greater or lesser distance, according to the size of the
ganglion, and changing their relative situation, are again com-
bined in cords, which recompose the nerve.

These fibres appear to be surrounded by a fine cellular
substance, which is vascular, moist, and soft. It is asserted
that, in fat subjects, an oily substance, resembling fat ; and in
hydropic subjects, a serous fluid has been found in this texture.

Ganglions are often connected with but one nerve, which
seems to enter at one extremity and go out at the other. But
they frequently receive additional branches from other nerves,
and send off additional branches to parts different from those to
which their principal nerves are directed. When connected with
but one nerve, they have been called simple ganglions : when
they receive and give off additional branches, they are denomi-
nated compound ganglions. It does not appear that there is any
important difference in their structure, in these cases.

The simple ganglions occur in the nerves of the spinal mar-
row— the posterior fasciculus of the nerves having always
formed a ganglion before it is joined to the anterior fasciculus.
The sympathetic nerve, throughout its whole extent, forms com-
pound ganglions.

The use of this particular structure does not appear to be
perfectly known. It seems, however, certain, that the different
fibres — (of which the nerves forming ganglions are composed)
— are blended together and arranged in a manner different

484 NERVES OF THE BRAIN.

from that in which they were arranged before the nerve entered
the ganglion.

It ousht to be observed, that the combination of nervous
fibrillae, so as to bring together those fibrils which originally
belonged to different cords, seems to have been kept in view
throughout the whole arrangement of the nervous system. It
is not only in the plexus and the ganglion that this appears,
but, also, in some of the larger nerves ; for in them the fibres
which form the cords that compose the nerve, instead of run-
ning parallel to each other, along the whole extent of the
nerve, form a species of plexus in their course, separating
from the fibres with which they were originally combined,
and uniting with the fibres of other cords ; as in other cases of
plexus.*

There have been doubts respecting the possibility of a repro-
duction of the substance of the nerves when it has been de-
stroyed ; but it appears to have been clearly proved by the
experiments of Mr. Haighton and others, that a reproduction
does really take place so as to continue on the transmission of
the nervous fluid .f

Nine pair of nerves proceed from the brain through the fora-
mina of the cranium. They are called Nerves of the Brain,
or Cerebral Nerves. One pair passes off between the cranium
and the spine, which is called Sub- Occipital. Twenty-nine
or thirty pair pass through the foramina of the spine : they are
denominated Cervical, Dorsal, Lumbar, and Sacral, from the
bones with which they are respectively connected. There are
seven pair of cervical nerves, twelve dorsal, five lumbar, and
five or six sacral — amounting, with the nerves of the brain, to
thirty-nine or forty pair.

Nerves of the Brain.

The nerves which go off from the brain and medulla oblon-
gata are named numerically, according to the order in which
they occur, beginning with the anterior. They also have other

* See Monro's Observations on the Structure and Functions of the Nervous
System. Plate xviii.
t See London Philosophical Transactions, for 1795, Part I.

FIRST PAIR OF NERVES.

485

names, which generally are expressive of the functions of the
different parts to which they are distributed.

Those which go to the nose are anterior to all the others, and
are, therefore, denominated

The First Pair, or the Olfactory Nerves.

They arise by three delicate white fibres (or roots) from the
under and posterior part of the anterior lobes of the brain, being
derived from the Corpora Striata. They proceed forward to
the depression on the cribriform plate of the ethmoid bone, on
each side of the crista galli. — They lie in this course between
the pia mater and arachnoid imbedded in the sulcus between two
convolutions — . The upper surface occupies a small sulcus
formed by the convolutions of the lower surface of the brain,
and, therefore, has a longitudinal ridge on it. The lower surface is
flat. Their texture is like that of the medullary part of the brain.

On each side of the crista galli each of them forms a pulpy
enlargement of a brownish color, which is called the bulb, and
has been considered as a ganglion.

Fig. 206.*

From this bulb many fine and delicate cords go off, which
proceed through the dura mater and the foramina of the cribri-

* Olfactory nerve, with its bulb ; and the branches which it sends to the lin-
ing membrane of the inner wall of the nostril, or septum. — The other division
of its branches, sent to the upper and middle turbinated bones, have been
41*

486 SECOND PAIR OF NERVES.

form plate to the Schneiderian membrane. — These ramifications
of the olfactory nerve seem to receive a coat from the dura
mater, as they are much more firm after they have passed through
it. They appear to be arranged in two rows as they proceed
from the ethmoid bone — one running near to the septum, and
supplying the upper part of the membrane covering it; and the
other to the opposite surface of the ethmoid bone so as to be
distributed over the upper and middle turbinated bones. — -

The Second Pair, or the Optic Nerves,

Originate from the Thalami Nervorum Opticorum, and appear
on the external and lower surface of the brain, on each side of
the sella turcica.

— Each optic nerve has two roots one from the thalamus, and
one from the nates of the lubercula quadrigemina. —

Each of them seems like a chord of medullary matter en-
closed in a coat derived from the pia mater, and has not the
fasciculated appearance of the other nerves. The medullary
matter, however, appears to be divided by processes that pass
through it, which are derived from the coat of the nerve.

They proceed obliquely forward and inward, on each side
of the sella turcica, in contact with the brownish cineritious
substance, (^pons Tarini,) in which the infundibulum and the

removed in the section, which has been made longitudinally, through the left
nostril just to the left side of the septum, leaving the right nostril entire. 1,
Frontal sinus. 2, Os nasi. 3, Crista galli of the ethmoid. 4, Sphenoidal
sinus. 5, Sella turcica. 6, Basilar process of the occipital bone joining the
body of the sphenoid. 7, Posterior opening of the right nostril. 8, Trumpet
shaped orifice by which the Eustachian tube of the right side opens into the
pharynx. 9, Velum pendulum palati or soft palate, cleft near its middle.
10, Line of section of the hard or bony palate. «, Olfactory nerve, b, Its
three roots of origin, c, Its bulb, from which, the filaments are seen proceed-
ing through the cribriform plate of the ethmoid, to supply the septum narium.
d, Nasal branch of the ophthalmic nerve ; this branch after being reflected
back from the orbit passes into the nostril, through the anterior foramen in the
cribriform plate, and divides there into two branches, e, Naso-palatine nerve,
a branch of the fifth pair. It comes off from the spheno-palatine ganglion or
ganglion of Meckel, gives off twigs to the lining membrane of the septum in
its course, passes through the foramen incisivum, where it forms the naso-pala-
tine ganglion or ganglion of Cloquet, is joined with its fellow of the opposite
side, and distributes branches (g) to the mucous membrane of the mouth cover-
ing the hard palate, h, Posterior palatine nerves, i, i, Septum nasi. —

THE THIRD AND FOURTH PAIR OF NERVES. 487

corpora albicantia of Willis are situated.* Anterior to this
substance they come in contact with each other, and again
separate, in such a way, that it is an undecided question whether
they decussate each other, or whether each forms an angle, and
is in contact with the other at the angle.

— The innermost fibres of the two nerves are now ascertained
to cross each other, those of the right side passing to the left
eye, and vice versa. The external portions of the nerve con-
tinue straight to the eye of the same side. —

From this place of contact, each nerve proceeds to its respec-
tive foramen opticum, where it receives a coat from the dura
mater, which extends with it to the eye, as has been described
in the account of that organ.

The Third Pair of Nerves,

Are sometimes called Motores Oculorum, in consequence of
their distribution to several muscles of the eye. They arise at
the inside of the crura cerebri, and make their appearance on
the basis of the brain, at the anterior part of the pons Varolii.

They originate by numerous threads, which soon unite so as
to form a cord, which passes through the dura mater, on each side
of the posterior clinoid process, and continues through the caver-
nous sinus, and the foramen lacerum, to the orbit of the eye.

Before this nerve enters the orbit it generally divides into two
branches which are situated one above the other. The Upper-
most Branch is spent principally upon the rectus superior mus-
cle of the eye, but sends a twig to the levator palpebrae. The
Inferior Branch is distributed to two of the recti muscles, viz.
the internus and the inferior, and also to the inferior oblique.
It likewise sends a twig to a small ganglion in the orbit, called
the Lenticular or Ophthalmic Ganglion,^ from which proceed
the fine ciliary nerves that perforate the sclerotic coat. J

The Fourth Pair of Nerves,
Are called the Pathetic, in consequence of the expression of

* See vol. ii. page 387.

f This ganglion, which is considered as among the smallest in the body, lies
on the outside of the optic nerve, near its entrance into the orbit, and is gene-
rally surrounded by soft adipose matter.

% See vol. ii. page 417.

488 FIFTH PAIR OF NERVES.

the countenance produced by the action of the muscle on which
they are spent. They arise froai the sides of the valve of the
brain, below and behind the tubercula Quadrigemina,* and are
so small that they appear like sewing threads. They proceed
round the crura of the cerebrum, and appear on the surface
between the pons Varolii and the middle lobes of the brain.
They proceed along the edge of the tentorium, which they per-
forate, and passing through the upper part of the cavernous
sinus, enter the orbit by the foramina lacera. They are exclu-
sively appropriated to the Superior Oblique or Trochlearis muscle.

The Fifth Pair of Nerves,

Are called Trigeminus, because each nerve divides into three
great branches.

These nerves come out from the crura of the cerebellum
where they unite to the pons Varolii, by distinct fibres, which
are connected so as to form a cord or nerve, that is larger than
any other nerve of the brain. In many subjects this cord
seems partially divided into two portions, the anterior of which
is much smaller than the posterior, and appears softer at its origin.

It passes into a short canal formed by the dura mater, near
the anterior extremity of the petrous portion of the temporal
bone, at a small distance below the edge of the tentorium. It
is perfectly loose and free from adhesion to the surface of this
canal : but it soon passes out of it under the dura mater, and
then adheres to that membrane. After leaving the canal, it
expands like a fan, but still consists of fine fibres, which have
some firmness. It is said that there are seventy or eighty of
these fibres in the expansion, but they appear to be more numer-
ous. Round the circumference of the expansion is a substance
of a brownish color, into which the fibres enter. This is the
Semilunar Ganglion, or the Ganglion of Gasser, and from it
the three nerves go off.

— If the ganglion be carefully turned out of its bed it will be
found to belong only to the large posterior root of the nerve,
which is considered the sensitive tract. The small or anterior
root which is called the matartract, merely lies in contact with

* See vol. ii. page 391.

OPHTHALMIC NERVE.

489

the under surface of the ganglion without passing through it and
can be traced along with the inferior maxillary nerve to the mus-
cles of mastication. —

The three nerves pass off from the convex or anterior side of
the ganglion, and are denominated the Ophthalmic, the Saptrior
JMnxillary, and the Inferior Maxillary.

The Ophthalmic Nerve,

Is a trunk of about three quarters of an inch long; it passes
into the orbit of the eye through the foramen lacerum : and it
there divides into several branches, which are called, from their
distribution, the Frontal or Supra Orbitar, the Nasal and the
Lachrymal.

Fig. 207.*

* A diagram, showing the fifth pair of nerves with its branches. 1. The
origin of the nerve by two roots. 2. The nerve escaping from the cms cere-
belli. 3. The Gasserian ganglion. 4. Its ophthalmic division. 5. The frontal
nerve, giving off the supra-trochlear branch, and escaping on the forehead
through the supra-orbital foramen. 6. The lachrymal nerve. 7. The nasal
nerve, passing at 8 through the anterior ethmoidal foramen, and giving off the
infra-trochlear branch. 9. The communication of the nasal nerve with the
ciliary ganglion. 10. A small portion of the third nerve with which the gang-
lion is seen communicating ; the ganglion gives off the ciliary branches from its
anterior aspect. 11. The superior maxillary nerve. 12. Its orbital branch.
13. The two branches communicating with Meckel's ganglion ; the three
branches given off from the lower part of the ganglion are the posterior palatine
nerves. 14, 14. The superior dental nerves, posterior, middle, and anterior.

490 OPHTHALMIC NERVE.

The Frontal or Supra Orhitar branch proceeds forward io
the upper part of the orbit, exterior to the membrane which
lines it, and divides into two ramifications. One of these is
small, (^siipra-trochlear,) and passes out of the orbit near the
pulley of the superior oblique, to be spent upon the orbicularis
muscle and the contiguous parts.

The other ramification, the proper supra-orbital, passes
through the supra orbitary foramen, or through the notch,
which is in the place of that foramen, and divides into a num-
ber of twigs, some of which pass transversely towards the
side of the head, and communicate with twigs from the portio
dura. Most of the others extend upwards on the head. Some
are distributed to the anterior part of the occipito-frontalis
muscle, and the integuments of the forehead ; others are spent
upon the upper portion of the scalp. Some of the extreme parts
of these ramifications also communicate with the portio dura.

The Nasal Branch proceeds obliquely forward towards the
inner side of the orbit, and sends a twig in its course, to the
lenticular ganglion, called the ganglionic branch. It also
sends off some small twigs, to join the ciliary nerves which
go from the ganglion. These twigs are called ciliary or
iritic, as their distribution is upon the Iris. On the inside of
the orbit, a branch leaves it, called the internal nasal, which
proceeds through the Foramen Orbitare Internum Anterius
to the cavity of the cranium, and passes a small distance upon
the cribriform plate of the ethmoid bone, under the dura mater,
to a fissure in the said plate near the crista galli, through
which it proceeds into the cavity of the nose. Here it divides
into twigs, some of which pass on the septum near its anterior
edge, and terminate on the integuments at the end of the nose,
while others pass down on the inferior turbinated bone.

15. The infra-orbital branches distributed upon the cheeii. 16. The inferior
maxillary nerve, 17. Its anterior or muscular trunk. 18. The posterior trunk;
the two divisions are separated by an arrow. 19. The gustatory nerve. 20.
The chorda tympani joining it at an acute angle. 21. The submaxillary gang-
lion. 22. The inferior dental nerve. 23. Its mylo-hyoidean branch. 24.
The auricular nerve, dividing behind the articulation of the lower jaw, to reu-
nite and form a single trunk. 25. Its branch of communication with the facial
nerve. 26. Its temporal branch.

SUPERIOR MAXILLARY NERVE. 491

After parting with the ramifications to the nose, the remain-
der of the nasal branch, named external from its place of
distribution, continues to the internal canthus of the eye, and
sends twigs to the lachrymal sac, the caruncula lachrymalis, the
eyelids, and the exterior surface of the upper part of the nose.

The Lachrymal Branch receives a filament from the fourth
nerve in the cavernous sinus ; it proceeds obliquely forward
and outwards, towards the lachrymal gland. In its course, it
sends off a twig, which passes through the spheno-maxillary
fissure, and communicates with a twig of the upper maxillary
nerve, and one or more twigs that pass through foramina in
the malar bone to anastomose over the malar bone with
branches of tempero-malar and facial nerves. The main
branch passes to the lachrymal gland, and some twigs continue
beyond it to the contiguous parts.

The Superior Maxillary Nerve.

The second branch of the fifth pair is examined with great
difiiculty on account of its peculiar situation. It proceeds from
the semilunar ganglion, and passes through the foramen rotun-
dum of the sphenoid bone into the upper part of the zygomatic
fossa. In this situation it sends a twig called orbital to the
orbit by the spheno-maxillary fissure, and a branch, called the
Infra Orbitar, which appears like the main nerve as it preserves
a similar direction, to the infra orbitar canal. At the same place
it sends downwards two branches, which unite together almost
immediately after their origin, and, as soon as they have
united, enlarge into a ganglion.* The ganglion is called the
Spheno-palatine, or ganglion of MecTiel. It is rather of a tri-
angular figure, and lies very near the spheno-palatine foramen.
It gives off a posterior branch, which passes through the ptery-
goid foramen to the cavity of the cranium : some branches which
proceed through the spheno-palatine foramen to the nose, and
are called the Spheno- Palatine or Lateral JSasal Nerves : and
an inferior branch that proceeds through the posterior palatine
canal, and is called the Palatine Nerve.

The small branch, which wasfrst mentioned, as going to the

* Sometimes a single branch passes downwards instead of two ; but it forms
a ganglion in the same place.

492 SECOND BRANCH OF THE FIFTH PAIR.

orbit by the spheno-maxillary fissure, divides into two ramifica-
tions. One of them unites with a twig of the lachrymal branch
above mentioned, and passes out of the orbit, through a foramen
in the malar bone, to the face where it is distributed. The
other passes also through a foramen of the malar bone, into the
temporal fossa, and, after uniting with twigs from the Inferior
Maxillary Nerve, proceeds backwards and perforates the aponeu-
rosis of the temporal muscle, to terminate on the integuments of
the temporal region.

Before the Infra Orbitar branch enters the canal of that
name, it sends off two twigs, called Posterior Dental Nerves,
which pass downwards on the tuberosity of the upper maxil-
lary bone, and enter into small canals in that bone, that are
situated behind the antrum maxillare. They subdivide into
fine twigs that proceed forward to the alveoli of three or four
of the last molar teeth, and penetrate each of the roots by a
cavity at its extremity. Twigs also proceed from these nerves
to the posterior part of the gums and buccinator muscle.

After the posterior dental nerves have left it, the Infra Orbi-
tar nerve proceeds forwards in the canal of that name ; and
near the extremity of it, gives off the anterior dental nerve,
which accompanies it for some distance, and then proceeds down-
wards in a canal in the bone anterior to the antrum maxillare.
In its course this nerve divides into many fibres, which pass to
the roots of the incisor, canine, and small molar teeth, each in
its proper canal. These dental branches sometimes pass in the
antrum maxillare between the lining membrane and the bones.
The Infra Orbitar nerve passes out of the foramen upon the
cheek, and divides into several branches of considerable size,
which are distributed on the face from the side of the nose to
the back of the cheek, and also upon the under eyelid and the
upper lip.

The Pterygoid Nerve, or posterior branch, passes backwards,
from the ganglion to a canal in the base of the pterygoid process
of the OS sphenoides, and proceeds through it. After leaving
this canal, it passes through a substance almost as firm as carti-
lage, which closes the anterior foramen lacerum, at the basis of
the cranium, and divides into two branches. The smallest of

SECOND BRANCH OF THE FIFTH PAIR. 493

them, called the Vidian Nerve, proceeds with a small artery to
the small foramen or Hiatus Fallopii, on the anterior side of the
petrous portion of the temporal bone, and continues, through a
small canal, to join the portio dura of the seventh pair in the
larger canal called the Aqueduct of Fallopius, at the first turn in
that canal.* The other branch of the pterygoid nerve proceeds
to the foramen caroticum, and passes through it, with a twig of the
sixth pair, to join the first cervical ganglion o( ihe Intercostal Nerve.

The Spheno-P alatine , or Lateral Nasal Nerves, consist of
several branches which pass from the spheno-palatine ganglion
through the spheno-palatine foramen into the nose. Some of
them are distributed to that part of the pituitary membrane,
which is above the upper meatus, and others to the part which
is immediately below it. Some of the branches which thus
enter the nose are spread upon the septum ; one among them
extends upon it, downwards and forwards, to the anterior part
of the palatine process of the upper maxillary bone, where it
enters into the foramen incisivum, and terminates in the lining
membrane of the roof of the mouth.f — The naso-jjalaiine
ganglion, or ganglion of Cloquet is formed on this branch while
in the foramen. —

The Palatine Branch proceeds through the canal formed by
the upper maxillary and palate bones, to the roof of the mouth
and soft palate. Soon after its origin, it sends off a twig which
proceeds down a small canal that is behind it. It also sends
off, as it proceeds downwards, several twigs to that part of the
membrane of the nose which covers the inferior turbinated
bone. When it arrives at the roof of the mouth, it divides into
several branches which run forwards, and are distributed to
the membrane which lines the roof of the mouth. Some of its
branches pass to the soft palate, the uvula, and the tonsils ;
small filaments pass into the back part of the upper jaw.

* The late Mr. John Hunter believed that this nerve parts from the portio
dura at the lower end of the aqueduct, and is the chorda tympani.

f The curious distribution of this nerve appears to have been known to the
late John Hunter, and also to Cofnnnius ; it is minutely described by Scarpa,,
and is delineated by Soemmering in his plate of the nose. — See " Observations
on certain parts of the Animal Economy," by J. Hunter, p. 219, and also
Scarpa, " De Organo Olfactus." In this last are some interesting ob.servations
relative to the ducts of Steno.

VOL. II. 42

494

INFERIOR MAXILLARY NERVE.

The Inferior Maxillary Nerve, or the Third Branch of the
Fifth Pair,

Passes through the foramen ovale into the zygomatic fossa,
and divides into tivo branches, one of which, the external,
sends ramifications to many of the contiguous muscles, as the
temporal, the masseter, the buccinator, the pterygoid ; and,
also, to the anterior part of the ear and the side of the head.
The other internal branch passes between the pterygoid mus-
cles, and divides into two ramifications, one of which proceeds
to the tongue, and is called the. Lingual or Gustatory, while
the other passes into the canal of the lower jaw.

Fig. 208.* The Lingual Nerve proceeds

between the pterygoid mus-
cles, and, in its course, is joined
by the chorda tympani. It
continues forward between the
maxillary gland and the lining
membrane of the mouth ; and
passes near the excretory duct of
that gland, above the mylo-hy-
oideus and the sublingual gland
to the under side of the tongue,
near the point : it then divides
into a number of branches which
enter into that body between
the genio-hyoideus and lingu-
alis muscles. This nerve has
been supposed to be particular-
ly concerned in the function of
taste, because many of its branches continue to the upper sur-

* This cut exhibits the nerves distributed to the tongue and some neighbor-
ing parts. 1. A fragment of the temporal bone containing the meatus audito-
rius externus, mastoid and styloid processes. 2. Stylo-hyoid muscle. 3. Stylo-
glossus. 5. Tongue. 6. Hyoglossus muscle. 7. Genio-hyo-glossus muscle.
8. Genio-hyoideus ; the two last arise from the inner surface of the symphysis
of the lower jaw. 9. Sterno-hyoid muscle. 10. Sterno-thyroid. 11. Thyro-
hyoid, upon which the hyoid branch of the lingual nerve is seen ramifying.
12. Omo-hyoid muscle crossing the common carotid artery (13) and internal
jugular vein (14.) 15. The external carotid giving off its branches. 16. The
internal carotid. 17. The Ungual or gustatory branch of the third division of

THE LINGUAL NERVE. 495

face of the tongue, especially near the point. In its course it
has a communication with the ninth pair of nerves, and sends
twigs to the membrane of the mouth and gums, and the con-
tiguous parts.

After parting with the lingual nerve, the inferior maxillary
continues to the upper and posterior orifice of the canal in the
lower jaw. Before it enters this canal it sends a branch to the
submaxillary gland, and to the muscles under the jaw.* It
then enters the canal, attended by blood-vessels, and proceeds
along it to the anterior maxillary foramen, on the side of the
chin, through which it passes out. In this course it sends
twigs to the sockets of the teeth, and generally supplies all the
large and one of the small grinders. Before it leaves the jaw
it sends a branch forward in the canal of the bone, which sup-
plies the remaining teeth on the side to which it belongs. After
passing out, through the anterior foramen, it is spent upon the
muscles and integuments of the front of the cheek, the chin and
the under lip.

— A branch of some importance called the Anterior auricular,
comes off from the inferior maxillary nerves between the
pterygoid muscles. It passes backwards and in close contact
with the articulation of the jaw, and there forms a plexus.
From this plexus two branches are sent off. One called
ascending or temporal, ascends to the front of the ear, and is
distributed on the scalp in company with the branches of the
temporal artery. It supplies the pinna and meatus of the ear,
and communicates with the facial nerve and various branches

the fifth pair, giving off a branch to the submaxillary ganglion (18) and com-
municating a little farther on with tlie hypoglossal nerve. 19. The duct of the
submaxillary gland, or duct df Wharton, passing forwards to the sublingual
gland, 20. The glosso-pharyngeal nerve. 21. The hypoglossal nerve curving
round the occipital artery. 22. The descendens noni nerve, forming a loop
with (23), the communicans noni, which is seen to arise by filaments from the
upper cervical nerves. 24. The pneumogastric nerve, emerging from between
the internal jugular vein and the common carotid artery, and entering the chest.
25. The facial nerve, emerging from the stylo-mastoid foramen, and crossing
the external carotid artery.

* The branch which passes from the lingual nerve to the sulmaxiUary gang-
lion, see fig. 208, is now generally considered to be a continuation of the chorda
tympani, which passing down in the sheath of the lingual nerve to the capsule
of the submaxillary gland, terminates in the submaxillary ganglion. — p.

496 SIXTH PAIR OF NERVES.

of the superior maxillary. The descending also sends branches
to the external ear ; it supplies the parotid gland, and com-
municates with the inferior dental and auricularis magnus
nerve. —

The Sixth Pair of Nerves,

Are called Motores Externi. They arise from the com-
mencement of the medulla oblongata, and proceed forward
under the pons Varolii. They proceed through the dura mater
on the inside of the fifth pair; they appear to pass through the
cavernous sinuses, but are enclosed in sheaths of cellular mem-
brane while they are in those sinuses. When in this situation
they are near the carotid arteries, and each nerve sends off one
or more very fine twigs, which being joined by a twig from
the pterygoid branch of the fifth pair, descend along the carotid
artery through the carotid canal, and then unite themselves to
the upper extremity of the upper cervical ganglion of the
intercostal nerve.

The sixth pair afterwards pass into the orbit of the eye,
each through the foramen lacerum of its respective side, and is
spent upon the Rectus Externus or Abductor muscle of the eye.

The Seventh Pair of Nerves

Comprises two distinct cords, which have very different des-
tinations ; and have, therefore, been considered as different
nerves, by several anatomists. One of these cords is appro-
priated to the interior of the ear, and is the proper Auditory
Nerve. The other is principally spent upon the face, and,
therefore, has been called the Facial. They have, however,
more frequently been denominated the Seventh Pair, and dis-
tinguished from each other, in consequence of a great differ-
ence in their texture by the appellations of Portio Dura and
Portio Mollis.

These two cords pass off nearly in contact with each other,
from the side of the upper part of the Medulla Oblongata,
where it is in contact with the pons Varolii ; but the Portio
Mollis can be traced to the fourth ventricle, while the Portio
Dura is seen to come out from the union of the pons Varolii

SEVENTH PAIR OF NERVES. 497

with the medulla oblongata and the crura cerebelli. The
Portio Dura, at its origin, is on the inside of the Portio Mollis.
Between these cords are one or more small fibres, called
Portio Media, which seem to originate very near them, and
finally unite with the Portio Dura.

Each of the seventh pair of nerves, thus composed, proceeds
from its origin to the meatus auditorius internus of the tempo-
ral bone; there the portio mollis divides into fasciculi, which
proceeds to the different parts of the organ of hearing in the
manner described in the account of the ear.*

The Portio Dura enters an orifice at the upper and anterior
part of the end or bottom of the Meatus Auditorius Inter-
nus. This orifice is the commencement of a canal, which has
been called the Aqueduct of Fallopius, and proceeds from the
Meatus Auditorius Internus to the external foramen, between
the mastoid and styloid processes at the basis of the cranium.
This canal first curves backwards and outwards, near to the
upper surface of the petrous bone, then forms an acute angle,
and proceeds, (backwards and downwards,) to the stylo-mas-
toid foramen, passing very near the cavity of the tympanum
in its course.

The Portio Dura, as it passes into the canal from the meatus
internus, seems to receive an investment from the dura mater.
It fills up the canal, but does not appear to be compressed.
Near the angle it is joined by the twig of the Vidian nerve,
which proceeds from the pterygoid branch of the fifth pair and
enters the petrous bone by the small foramen innominatum on
its anterior surface. In its course through the canal it sends
off some very small twigs to the muscles and appurtenances of
the small bones of the ear, and to the mastoid cells ; and, when
it has arrived almost at the end of the canal, it sends off in a
retrograde direction, a small branch which proceeds into the
cavity of the tympanum, (entering it by a foramen near the
base of the pyramid,) and crosses the upper part of it, near the
membrana tympani, between the long processes of the Malleus
and Incus. This twig is the Chorda Tympani; it proceeds

* See vol. ii. p. 469.

42*

498

SEVENTH PAIR OF NERVES. PORTIO DURA.

from the cavity by a fissure on the outside of the Eustachian
tube, to join the lingual branch of the fifth pair, as has been
already mentioned.*

The Portio Dura, after passing out of the Foramen Stylo-
Mastoideum, is situated behind and within the parotid gland.

Fig. 209.t

* The late John Hunter believed that the chorda tympani is merely a con-
tinuation of the twig of the pterygoid branch which joins the portio dura above.
See Observations on certain parts of the Animal Economy, page 220.

•}■ The destribution of the facial nerve and the branches of the cervical
plexus. 1. The facial nerve, escaping from the stylo-mastoid foramen, and
crossing the ramus of the lower jaw ; the parotid gland has been removed in
order to see the nerve more distinctly. 2. The posterior auricular branch ; the
digastric and stylo-mastoid filaments are seen near the origin of this branch.
3. Temporal branches, communicating with (4) the branches of the frontal
nerve. 5. Facial branches, communicating with (6) the infra-orbital nerve.
7. Facial branches, communicating with (8) the mental nerve. 9. Cervico-
facial branches, communicating with (10) the superficialis colli nerve, and
forming a plexus (11) over the submaxillary gland. The distribution of the
branches of the facial in a radiated direction over the side of tlie face consti-
tutes the pes anserinus, 12. The auricularis magnus nerve, one of the ascend-
ing branches of the cervical plexus. 13. The occipitalis minor, ascending
along the posterior border of the sterno-mastoid muscle. 14. The superficial
and deep descending branches of the cervical plexus. 15. The spinal acces-
sory nerve, giving oS a branch to the external surface of the trapezius muscle.
16. The occipitalis major nerve, ihe posterior branch of the second cervical nerve.

EIGHTH PAIR OF NERVES. 499

Here it gives off a twig to the back of the ear and head called
the posterior auricular, one to the digastric and one to the
stylo-hyoideus muscles. It perforates the gland after sending
filaments to it, and then divides into branches which are
arranged in such a manner that they constitute what has been
called the Pes Anserinus.

To describe the various branches in this expansion would
be more laborious than useful. Some of them called tempero-
facial are spread upon the temple and the upper part of the
side of the head, and unite with the supra-orbitar branches of
the ophthalmic nerve. Some pass above and below the eye,
and are distributed to the orbicularis muscle, and communicate
with nervous twigs that pass through foramina in the malar
bone, &tc. Some large branches named facial pass trans-
versely. These cross the masseter muscle, and divide into
ramifications which are spent upon the cheek and the side of
the nose and lips, and communicate with the small branches of
the superior maxillary nerve.

A large number of branches, the cervico-facial, pass down-
wards. Many of them incline forwards, and are spent on the
soft parts about the under jaw ; while others proceed below
the jaw to the superficial muscles and integuments of the
upper part of the neck, communicating with the branches of
the contiguous nerves.*

The Eighth Pair of Nerves,

Are very frequently denominated the Par Vagum, on account
of their very extensive distribution.

They arise from the medulla oblongata between the Cor-
pora Restiformia and the Corpora Olivaria. Each nerve
consists of a cord, which is anterior, and called the Glosso-
Pharyngeal; and of a considerable number of small filaments,

* A most minute and labored description of the nerves of the face was pub-
lished by the celebrated Meckel, in the seventh volume of Memoirs of the
Royal Academy of Sciences of Berlin, for the year 1751, accompanied with a
plate, exhibiting the side of the head, of three times the natural size. This is
republished in the Collection Academique : Partie Etrang^re. — Tom. viii.

500 GLOSSO-PHARYNGEAL.

which arise separately, but unite and form another cord, the
proper Par Vagum. Associated with these is a third cord,
called the Spinal or Accessory Nerve of Willis, which origi-
nates in the great canal of the spine, and, passing up into the
cavity of the cranium, goes out of it with these nerves through
the foramen lacerum.

The two first mentioned nerves proceed from their origin to
the posterior foranien lacerum, and pass through it with the
Internal Jugular vein, — being separated from the vein by a
small process of bone. They are also separated from each
other by a small process of the dura mater. In the foramen
they are very close to each other; but soon after they have
passed through it, they separate and proceed towards their
different destinations.

The Glosso-Pharyngeal proceeds towards the tongue, be-
tween the stylo-pharyngeus and the stylo-glossus muscles, fol-
lowing the course of the last mentioned muscle to the posterior
part of the tongue. At the commencement of its course it
receives a twig from the Portio Dura, and one also from the
Par Vagum. It soon gives off a branch which passes down
on the inside of the common carotid to the lower part of the
neck, where it joins some twigs of the intercostal to form the
cardiac nerves. Afterwards it sends off several twigs to the
muscles of the pharynx and its internal membrane, and also
some twigs which unite with others from the upper cervical
ganglion of the Sympathetic, and form a network that lies
over the anterior branches of the external carotid. The Glosso-
pharyngeal finally enters the tongue, at the termination of
the hyo-glossus muscle ; and after sending branches to the
lingualis, and the various muscles inserted into the tongue,
terminates in small ramifications that are spent upon the sides
and middle of the root of the tongue, and upon the large pa-
pillae.

— It sends off likewise two or three filaments to supply the
stylo-pharyngeus muscle, and tonsillitic branches which form-
ing a circular plexus round the base of the tonsil gland
communicate with the posterior palatine nerves that come off

;'iJ;lSb'^;'";'/:»it

PAR VAGUM. 501

from the ganglion of Meckel. While situated in the jugular
fossa the pneumogastric exhibits two gangliform enlargements ;
one, the Superior, called the jugular ganglion of Miiller, the
second, the inferior, named the ganglion of Andersch, or the
petrous ganglion. From the latter passes olFthe tympanic nerve
{Jacobson''s nerve) to supply the tympanic cavity as described in
the account of the ear. —

The Par Vagum

— As it passes through the anterior part of the foramen lace-
rum presents a small rounded ganglion embraced by the dura
mater which forms a canal about the nerve. Shortly after
it has passed through the foramen lacerum, it forms a
ganglionic enlargement of about an inch in length, from which
a number of white nerves proceed, anastomosing with the
surrounding trunks. —

As it descends, it adheres to the superior ganglion of the
intercostal, and also to the ninth pair. It proceeds behind
and on the outside of the carotid, and is contained in the
same sheath of cellular membrane which encloses that artery
and the Internal jugular vein. Each of these nerves, soon after
it leaves the cranium, gives a twig to the glosso-pharyngeal ;
soon after that it sends off a branch called the Pharyngeal,
which unite to one from the accessory nerve, and to one or
more from the glosso-pharyngeal, and proceeds to the middle
constrictor of the pharynx, when it expands into ramifications
that form a plexus from which proceed a number of small twigs
that go to the larynx, and some that pass down on the common
carotid artery.

It then sends off, downward and forward, the Superior
Laryngeal nerve, which continues in that direction behind
the carotid artery, and divides into an external and internal
branch.

The Internal Branch, which is the largest, proceeds be-
tween the OS hyoides and the thyroid cartilage ; and divides Into
numerous ramifications which are distributed to the arytenoid

502 PAR VAGUM.

muscles and to the membrane which lines the larynx and
covers the epiglottis. It is said that fine twigs can be traced
into the foramina, which are to be seen in the cartilage of
the epiglottis ; — some ramifications can be traced to the pha-
rynx ; — others communicate with the branches of the recurrent
nerve.

The External Branch sends twigs to the pharynx, to the
lower and inner part of the larynx, and to the thyroid gland.

In its course downwards, the great nerve sometimes sends off
a twig, which unites with one from the ninth pair that passes to
the sterno-hyoidei and sterno-thyroidei muscles.

It uniformly sends off one or more twigs called cardiac,
which pass into the thorax and combine with small branches
from the sympathetic or intercostal nerve, to form the Cardiac
plexus, which sends nerves to the heart.

After entering the thorax, the right trunk of the Par Va-
gum passes before the subclavian artery ; and the left trunk
before the arch of the aorta ; and immediately after passing
these arteries, each of the nerves divides into an anterior and
posterior branch. The anterior is the continuation of the Par
Vagum ; the posterior is a nerve of the Larynx ; which from its
retrograde course, is called the Recurrent or Inferior Laryngeal
Nerve. *

On the left side the Recurrent Nerve winds backwards round
the aorta, and, on the right side, round the subclavian artery,
and proceeds upwards, deeply seated, on the side of the tra-
chea, to the Larynx. Soon after its origin it sends filaments
to a ganglion of the sympathetic, to the cardiac plexus, and to
a pulmonary plexus, soon to be mentioned. In its course
upwards, it sends twigs to the trachea and the oesophagus. It
proceeds behind the thyroid gland, and sends twigs to that
organ. At the lower part of the larynx it sends off a branch
which communicates with branches of the superior laryngeal
nerve. It also divides into branches which are spread upon
the posterior crico-arytenoid and the arytenoid muscles ;
and also upon the lateral crico-arytenoid and the thyro-aryte-
noid muscles, as well as upon the membrane which lines the

PAR VAGUM. 503

back part of the larynx and the contiguous surface of the
pharynx.

There is a difference in the arrangement of the recurrents on
the different sides, in consequence of one winding round the
aorta, while the other winds round the subclavian artery.

— The superior laryngeal nerve is the proper nerve of sensa-
tion to the larynx, and is chiefly distributed on its mucous mem-
brane. The recurrent is the nerve of motion to this organ, and,
as above described, is mainly spent upon its muscles. —

After sending off the recurrents, each trunk of the Par
Vagum proceeds behind the ramifications of the trachea ; but
previously detaches some small branches, which are joined by-
twigs from the intercostal and from the recurrent, and form a
plexus upon the anterior part of the vessels going to the lungs.
This Anterior 'plexus, after sending off some minute branches
to the cardiac nerves and the pericardium, transmits its branches
with ihe bronchia and the blood-vessels, into the substance of
the lungs.

Some of ihe branches which proceed from the par vagum,
pass down on the posterior part of the trachea, and enter into
the membrane which forms it, and the mucous glands which are
upon it ; and some pass to the oesophagus.

When the par vagum is behind the great vessels of the lungs,
a number of branches go off transversely, and are also joined
by some fibres from the sympathetic. These form the Posterior
'pulmonary plexus ; the ramifications from which proceed into
the substance of the lungs, and are principally spent upon
the ramifications of the bronchia. It has been said,* that the
small twigs into which they divide, very generally penetrate
into the small ramifications of the bronchia, and are spent
upon their internal membrane. The branches of the posterior
pulmonary plexus are more numerous than those of the
anterior.

Soon after sending off the nerves of the pulmonary plexus,
the Par Vagum proceeds downwards upon the oesophagus ;
the left nerve being situated anteriorly, and the right posteri-

* See Buisson, in the continuation of tlie Descriptive Anatomy of Bichat.

504

SPINAL ACCESSORY.

Fig. 210.* orly. Each of these nerves forms

a plexus known as the oesophageal,
which nearly surrounds the oesopha-
gus, as they descend on it ; but
the network is thickest on the pos-
terior side. They pass through the
diaphragm with the oesophagus,
and unite again so as to form con-
siderable trunks. These terminal
branches of the nerve are called the
gastric.

The Anterior, which is the small-
est, proceeds along the lesser curva-
ture of the stomach to the pylorus.
Some of its fibres are spread upon
the anterior side of the stomach and
the lesser omentum. Others of
them extend to the left hepatic, and
also to the solar plexus.

The Posterior trunk sends
branches to surround the cardiac
orifice of the stomach. Many
branches are spread upon the under
side of the great curvature of the
stomach. Some of them pass in
the course of the coronary artery to
the coeliac, and unite to the hepatic
and splenic plexus ; and one trunk,
which is thick, although short, pro-
ceeds to the solar plexus.

The Accessory Nerve of Willis,

Which has been mentioned as associated with the eighth

pair of nerves, within the cranium, has a very peculiar origin.

* Origin and distribution of the eighth pair of nerves. 1, 3, 4. The medulla
oblongata. 1. Is the corpus pyramidale of one side. 3. The corpus olivare.
4. The corpus restiforme. 2. The p6ns Varolii. 5. The facial nerve. 6. The
origin of the glosso-pharyngeal nerve. 7. The ganglion of Andersch. 8. The
trunk of the nerve. 9, The spinal accessory nerve. 10. The ganglion of the
pneumogastric nerve. 11. Its plexiform ganglion. 12. Its trunk. 13. Its

td.:4i.'-L>Sit„:,^i

NINTH PAIR OF NERVES. 505

It arises by small filaments, which come off from the spinal
marrow, between the anterior and posterior fasciculi of the
cervical nerves, and proceeds upwards to the great occipital
foramen, between these fasciculi. It commences sometimes
at the sixth or seventh cervical vertebra, and sometimes about
the fourth. It enters the cavity of the cranium through the
foramen magnum, and proceeds upwards and outwards, so as to
join the eighth pair of nerves at some distance from its origin, and
in this course it receives filaments from the medulla oblongata.

After approaching very near to the eighth pair of nerves,
it accompanies it to the foramen lacerum, and passes out in
its own separate sheath. It then leaves the eighth pair and
descends towards the shoulder, proceeding through the sterno-
mastoid muscle. Soon after it emerges from the cranium, it
sends a ramification to the pharyngeal branch of the Par
Vagum and another to the Par Vagum itself. After passing
through the upper and back part of the sterno-mastoid muscle
it terminates in the trapezius. It adheres to the ninth pair of
nerves as it passes by it, and sends a twig to the sub-occipital
and some of the cervical nerves. It also gives ramifications to
the sterno-mastoid muscle as it passes through it.

It has already been stated that the Laryngeal and Recurrent Nerves appear to
answer different purposes in their distribution to the Larynx. When both of
the recurrent nerves are divided in a living animal, the voice seems to be
lost. When the laryngeal nerves only are divided, the strength of the voice
remains, but it is flatter. The recurrent nerves, therefore, seem essential
to the formation of the voice. The laryngeal nerves are necessary to its
modulation.

The history of the investigation of this subject up to that time, is contained in
Mr. Haighton's paper in the third volume of Memoirs of the Medical Society
of London. The later researches of Mr. Reid and Mr. Hilton, may be
studied with advantage in regard to the structure and functions of the par
vagum nerves.

The Ninth Pair of Nerves.

Each of these nerves arises from the groove in the medulla

pharnygeal branch forming the pharyngeal plexus (14), assisted by a branch
from the glosso-pharyngeal (8), and one from the superior laryngeal nerve (15).
16. Cardiac branches. 17. Recurrent larvngeal branch. 18. Anterior pulmo-
nary branches. 19. Posterior pulmonary branches. 20. (Esophageal plexus.
21. Gastric branches. 22. Origin of the spinal accessory nerve. 23. Its
branches distributed to the sterno-mastoid muscle. 24. Its branches to the
trapezius muscle.

VOL. II. 43

506 CERVICAL NERVES.

oblongata, between the corpora pyramidalla and the corpora
olivaria. Three or four fasciculi of distinct filaments, unite
to form it. Thus composed, it proceeds to the anterior condy-
loid foramen of the occipital bone, and passes through the
dura mater. It seems firmly united, by the cellular mem-
brane, to the eighth pair, and to the first ganglion of the
sympathetic, soon after it passes from the occipital bone. It
is either connected to the sub-occipital nerve by a small
ramification, or it joins a branch which proceeds from the
sub-occipital to the cervical, and bends round the transverse
process of the atlas. It passes between the internal carotid
artery and the internal jugular vein, and crosses the external
carotid at the origin of the occipital artery. At this place it
generally sends downwards a large branch which is called the
Descendens Noni. Passing forwards, it is on the outside of
the posterior portion of the digastric muscle, and inclines
downwai'ds ; but near the tendon of the muscle it turns
upwards, and proceeds on the inside of the mylo-hyoideus,
where it divides into ramifications, which, at the anterior
edge of the hyo-glossus muscle, begin to enter the substance
of the tongue, between the genio-glossus and the lingualis
muscles.

Some of the branches of this nerve unite with those of the
lingual branch of the fifth pair. Others are distributed to
almost all the muscles connected with the tongue.

— It also interchanges filaments of communication, with the
pneumogastric and spinal accessory at the base of the skull
behind the internal jugular vein. Branches likewise pass
between it and the superior cervical ganglion. —

The branch called descendens noni passes down in the
course of the common carotid artery, and sends fibrils in
its progress to the upper portions of the omo-hyoid and sterno-
thyroid muscles ; it unites with ramifications of various sizes
from the first, second, and third cervical nerves, which form a
bow under the sterno-mastoid muscle, from which ramifications
go to the lower portions of the sterno-hyoid and thyroid muscles,
and of the omo-hyoid.

CERVICAL NERVES. 507

Of the Cervical iSlerves.

The tenth or last pair of the head, commonly called the
Sub-occipital, may be arranged with these nerves, because it
arises, like them, from the medulla spinalis, and is distributed
to the muscltfs on the neck. — If counted with the cervical
nerves it will make eight pair to the neck. —

The Sub-occipital Nerves

Arise on each side of the spinal marrow, nearly opposite to
the interval between the great foramen of the os occipitis and
the atlas.

Each of these nerves consists of an anterior and posterior
fasciculus, or bundle of fibres, which pass outwards immedi-
ately under the vertebral arteries between the os occipitis and
the atlas, and form a ganglion, from which proceed an anterior
and a posterior branch.

The anterior branch is united to the second cervical nerve
below, and to the ninth nerve, or the hyoglossal, above. It
also sends filaments to the upper ganglion of the great sympa-
thetic nerve.

The posterior branch is spent upon the Recti, the Obliqui,
and some other muscles of the head.

The proper Cervical Nerves consist of seven pairs ; of which
the first six go off between the vertebrae of the neck, and the
seventh between the last of the neck and the first of the back.

The First Cervical Nerve,

Passes out between the atlas and the Vertebra Dentata. It
originates from two fasciculi, which are connected to each
other at a ganglion, and then separate into an anterior and a
posterior branch.*

The anterior branch is connected by filaments with the
accessory nerve, with the ninth pair of the head, and with
the upper ganglion of the sympathetic. It is also connected

* This arrancrement is common to the nerves of the spine. The ganglion is
formed in all the spinal nerves by the posterior fasciculus.

508 CERVICAL NERVES.

with the second cervical nerve, and sends some branches to
the muscles on the anterior part of the spine.

The posterior branch, after communicating with the poste-
rior branches of the sub-occipital and the second nerves of the
neck, perforates the complexus muscle, and ascending upon
the back of the head, is distributed with the occipital artery.

The Second Cervical Nerve,

Sends off, from its Anterior Branch, a twig which descends
to the lower cervical ganglion of the sympathetic, and a con-
siderable ramification to the third cervical nerve. It also sends
off some twigs to the sterno-mastoid muscle, and others to join
the accessory nerve. Some of its small ramifications pass
down upon the external jugular vein, and others unite with
the descending branch of the ninth pair of the head. A small
branch is also concerned in the formation of the phrenic nerve.
Two larger branches of this nerve wind round the posterior
edge of the sterno-mastoid, and are spread under the integu-
ments of the anterior, lateral, and posterior parts of the neck
and lower parts of the head ; they have a communication
with the portio dura of the seventh pair.* — These two branches
are called the auricularis magmis and the superjicialis colli.
They both receive filaments from the third cervical nerve.
They wind over and cross the outer surface of the sterno-
cleido-mastoid. The auricularis is directed to the ear, sends
branches to the pinna and lobus, to the integument over the
parotid gland and the skin behind the ear. The superficialis
colli passes forward in the direction of the submaxillary gland
over which it assists in forming a plexus and sends branches
to the integuments of the side of the neck, the chin, and side
of the face, and anastomoses with branches of the facial. The
posterior branch of the second cervical nerve called occipitalis
major, is spent upon the extensor muscles of the head and
neck. — Another small branch from the second cervical named

* These superficial branches have sometimes been described as coming from
a plexus ; but they often arise directly from the second cervical nerve.

CERVICAL NERVES. 509

the occipitalis minor runs up along the posterior border of the
sterno-cleido-mastoid to be distributed to the integuments of the
side and back part of the head. See fig. 209.

The Third Cervical Nerve,

Sends down, from its Anterior Branch, the principal trunk
of the phrenic nerve. It also sends twigs to the fourth cervi-
cal, to the lower cervical ganglion of the intercostal, and to the
descendens noni of the hypoglossal. Some of its branches
unite with .twigs of the accessory nerve, and others are spent
upon the muscles and integuments of the shoulder and lower
part of the neck. A small Posterior Branch is spent upon the
muscles of the back of the neck.

Cervical Plexus.

— The successive anastomosing loops and communications,
which take place between the branches above described as
coming off from the sub-occipital and the three upper cervical
nerves, and the neighboring nervous trunks, form a mesh or
network of nervous filaments that has received the name of
cervical 'plexus. This plexus is divided into the Anterior and
Posterior. The anterior, which is much the larger, is formed
from the anterior branches of the nerves. This plexus rests
beneath the platysma and sterno-cleido-mastoid muscles, and
covers the outer surface of the levator scapulae, middle sca-
lenus, and splenius muscles. The neighboring nerves with which
it has communication are the spinal accessory, the pneumogastric,
the sympathetic, and the hypoglossal ; it forms a junction also
with the descending branch of this latter nerve {descendens noni)
by a distinct cord called the communicons noni, which two trunks
form a loop over the carotid vessels.

— The posterior branches given off by each one of these same
cervical nerves and the sub-occipital just as they emerge from
the spinal column, form in a similar manner the posterior cer-
vical plexus, which is placed between the complexus and
semlsplnalls colli muscles. The branches forming this plexus
are intended as has been already described, for the sup-
43*

510 ' CERVICAL NERVES.

ply of the muscles and integuments on the back part of the head
and neck — .

The Nerves of the Diaphragm,

Are generally denominated the Phrenic. The principal
root of each of them is commonly derived from the third cer-
vical nerve, but frequently the second and the fourth cervical
nerves contribute to their formation ; they are sometimes also
joined by a twig which is derived from the ninth pair.

Each nerve proceeds down the neck, between the rectus
capitis major and the scalenus anticus, and continues across
the fore part of the latter muscle ; it descends into the thorax
within the anterior end of the first rib, between the sub-
clavian vein and the artery. It sometimes receives a twig
from the fifth cervical nerve, and a twig passes between it and
the great sympathetic. After entering the thorax, they de-
scend, attached to the, mediastinum, before the root of the
lungs. In consequence of the projection of the point of the
heart to the left, the course of the left is a little different from
that of the right ; that of the right proceeding in a more per-
pendicular direction. When they arrive at the diaphragm,
they divide into many ramifications, which have a radiated
arrangement, and terminate on the fibres of that muscle, both
on the upper and lower surface. Some fibres from each nerve
are continued downward, and communicate in the abdomen with
the fibres of the sympathetic.

— The descending branches may readily be traced into
the phrenic and solar plexus. Those of the right phrenic
nerve may in addition be traced into the hepatic plexus. Upon
the branches of this nerve in the upper surface of the dia-
phragm, I have occasionally found distinct ganglia deve-
loped.—

The Fourth, Fifth, Sixth and Seventh Cervical Nerves,

May be comprised in one description. They pass off suc-
cessively from the medulla spinalis between the vertebrae,
like the other nerves. Their Posterior Branches are generally

BRACHIAL PLEXUS.

511

distrlbated to the back of the neck, and are very small. Their
Anterior Branches are principally appropriated to the upper
extremities, and are very large. They generally send each a
small twig to the lower cervical ganglion of the intercostal
nerve, and a few small branches to some
of the contiguous muscles. They are
arranged and combined so as to form the
net- work, now to be described, which is
called the Brachial or Axillary plexus ;
and, in the formation of this plexus, they
are joined by the anterior branch of the
first dorsal nerve.

The Brachial Plexus

Extends from the lower part of the
side of the neck into the arm-pit. It
commences in the following manner. The
fourth and fifth cervical nerves proceed
downwards, and after uniting to each other
about an inch and a half below their
egress from the spine, they separate again,
almost immediately, into two branches.

The sixth cervical nerve, after passing
downwards, divides also into two branches,
one of which unites with the upper-,
most branch that proceeds from the union
of the fourth and fifth, and the other
with the lowermost, and they all proceed
downwards.

* The Brachial plexus of nerves with its branches and their distribution. 1.
The brachial plexus. 2. The short thoracic nerves. 3. The long thoracic or
external respiratory of Bell. 4. The phrenic nerve. 5. The supra-scapular
nerve. 6. The subscapular nerves. 7. The external cutaneous nerve. 8.
The point at which it pierces the deep fascia. 10. The origin of tlie median
nerve by two heads. 11. The bend of the elbow where the median passes be-
tween the two heads of the pronator radii teres, and of the flexor sublimis digi-
torum. 12. Its muscular branches. 13. Its anterior interosseous branch. 14.
The point at which the nerve passes beneath the annular ligament, and divides
into six terminal branches. The branch which crosses the annular ligament is

512 NERVES OF THE ARM.

The seventh cervical is joined by the first dorsal, which pro-
ceeds iijjwards, and unites with it at a short distance from the
spine. The cord produced by their junction soon unites with
one of the cords above described. As these different cords pro-
ceed downwards, they divide, and their branches again unite.
The axillary artery, which passes in the same direction, is sur-
rounded by them. In this manner the axillary plexus is com-
monly formed.

The muscles about the shoulder, both before and behind are
supplied by the axillary plexus. Thus, it sends two branches
called the Short Thoracic to the Suh-scapularis, Teres Major,
and Latissimiis Dorsi, behind ; and to the Pectoralis Major
and Minor and the Mammary Gland. It also sends off a branch
called the Supra-Scapular or Scapularis, which commonly arises
from the upper part of the plexus, and proceeds through the
notch in the upper costa of the scapula to the supra and infra
spinatus, teres minor, he.

— Three or four small branches called Sub-Scapular, go to the
muscle of that name. An important branch called the Long
thoracic, or external respiratory of Sir Charles Bell, arises high
up in the plexus from the fourth and fifth cervical nerves and
descends along the side of the chest over the serratus major
amicus muscle to which it is distributed. —

Nerves of the Arm.

All the great nerves of the arm are derived from the axillary
plexus. There are six of them, which are denominated The
Musculo- Cutaneus ; The Median;* The Cubital, or Ulnar;

the superficial palmar. 15. The ulnar nerve giving off several muscular
branches to the triceps which have received no name. IG. The point at which
it passes between the two heads of the flexor carpi ulnaris. 17. Its dorsal
branch. 18. The termination of the nerve dividing into a superficial and deep
palmar branch. 19. The musculo-spiral nerve. 20. Muscular branches of
this nerve. 21. Spiral cutaneous nerve. 22. Posterior interosseous nerve,
piercing the supinator brevis muscle. 23. The radial nerve. The two last
nerves are the terminal branches of the musculo-spiral. 24. The point at
which the radial nerve pierces the deep fascia. 25. The circumflex nerve of
the shoulder joint.

* Sometimes called Brachial.

NERVES OF THE ARM. 513

The Internal Cutaneiis ; The Radial or Muscular S])iral ;
and ihe Circumjlex or Articular.

The Musculo- Cutaneous,

External Cutaneous, or Perforating Nerve of Casserius,
passes obliquely through the upper part of the coraco-brachialis
muscle. Before it enters the muscle, it sends a branch to it.
After leaving the muscle it passes down the arm between the
biceps and the brachialis internus, to which it also gives
branches. It proceeds to the outside of the biceps, and con-
tinues under the median cephalic vein to the anterior and ex-
ternal part of the fore-arm ; along which it passes under the
integuments. — It perforates the fascia so as to become sub-
cutaneous at the outer part of the bend of the elbow. — On the
lower part of the fore-arm it divides into many branches,
which extend to the root of the thumb and back of the head,
and terminate in the integuments.

The Median Nerve,

Which is one of the largest of the arm, often proceeds from
the axillary plexus next to the musculo-cutaneus ; it passes
down the arm, very near the humeral artery, within the edge
of the biceps flexor muscle, and, during this course, gives off
no branches of any importance. — It comes off from the plexus
by two roots which embrace between them the axillary artery ;
a fact which it is injportant to recollect in ligature of this
vessel in the axilla. — After passing the bend of the elbow, it
proceeds under the aponeurosis of the biceps, between the
brachialis internus and the pronator teres, and continues down
near the middle of the fore-arm, between the flexor sublimis
and the flexor profundus. At the elbow it sends branches to
, several nmscles on the anterior side of the fore-arm, and to the
integuments. Among these branches is one, called the Ante-
rior Interosseal Nerve, which passes down on the anterior
surface of the interosseal ligament, with the artery of that name.
This nerve sends branches, in its course, to the long flexor of
the thumb, and the deep flexor of the fingers. When it arrives

il4

NERVES OF THE ARM.

at the pronator quadratus, it sends branches to that muscle,
and, passing between it and the interosseus ligament, perforates
the ligament, and soon terminates on the posterior side of the
wrist and hand.

As the Median Nerve proceeds downwards, it becomes
more superficial ; and continuing among the tendons of the
flexors of the fingers, it gives off a branch called superficial
palmar which crosses the annular ligament and is principally-
spent upon the integuments of the ball of the thumb and the
Fig. 212.* palm of the hand. This great nerve

passes with the tendons under the an-
nular ligament ; and immediately after,
while it is covered by the Aponeurosis
Palmaris, and by that portion of the
artery which is called Arcus Sublimus,
it divides into six branches, one muscu-
lar and five digital, which separate from
each other at acute angles, and subdi-
vide so as to send a ramification to each
side of the thumb, one to the radial side
of the index, one which subdivides to
the adjoining sides of the index and
little finger, and one which branches in
like manner to the radial side of the
ring finger, and the ulnar surface of the
middle. The muscular branch goes to
the thumb.

* Relation of the nerves and veins at the bend of the elbow. 1. The radial
vein. 2. The cephalic vein. 3. The anterior ulnar vein. 4. The posterior
ulnar vein. 5. The trunk formed by their union. 6. The basilic vein, piercing
the deep fascia at 7. 9. A communicating branch between the deep veins of
the fore-arm and the upper part of the median vein. 10. The median cephalic
vein. 11. The median basilic. 12. A slight convexity of the deep fascia,
formed by the brachial artery. 13. The process of fascia, derived from the
tendon of the biceps, and separating the median basilic vein from the brachial
artery. 14. The external cutaneous nerve, piercing the deep fascia, and divid-
ing into two branches, which pass behind the median cephalic vein. 15. The
internal cutaneous nerve, dividing into branches, which pass in front of the
median basilic vein. 16. The intercosto-humeral cutaneous nerve. 17. The
spiral cutaneous nerve, a branch of the musculo-spiral.

NERVES OF THE ARM. 51'

The Cuhital or Ulnar Nerve

Is also of considerable size. It passes down on the inside of
the triceps extensor muscle, to the great groove formed by the
olecranon process and the internal condyle of the os humeri ;
and, in this course, it often sends a branch to the triceps, some
smaller twigs to the' upper part of the fore-arm, and one which
piercing the fascia anastomoses with the internal cutaneous.
From the groove it proceeds on the anterior part of the fore-
arm, between the flexor carpi ulnaris and the flexor sublimis,
to the wrist. At a small distance above the wrist it sends off
a branch, called the Dorsalis, which passes between the flexor
ulnaris and the ulna, to the bac4c of the fore-arm and wrist,
where, after sending ramifications to the integuments and con-
tiguous parts, it divides into branches which pass to the little
finger and the finger next to it. These branches send off, in
their course, many twigs which pass to the skin and cellular
substance.

The ulnar nerve then proceeds with the artery, over the
annular ligament, on the radial side of the os pisiforme, and
divides into two branches ; one of which is called the superfi-
cial, and the other the deep-seated palmar.

The Superficial divides into two principal branches, an
external and an internal. The external passes under the apo-
neurosis palmaris ; and, after sending a branch to combine
with one from the median and some twigs to the contiguous
muscle, it subdivides into two branches, one of which goes to
the ulnar side of the ring finger and the opposite side of the
little finger. The other branch sends off some twigs to the
muscles, and proceeds along the ulnar side of the little
finger.

The Deep-seated palmar branch of the ulnar nerve passes
between the muscles of the little finger, under the tendons of
the flexors, and accompanies the deep-seated arterial arch in
the palm of the hand, giving branches to the interossei, and
other contiguous muscles.

516 NERVES OF THE ARM.

The Radial or Musculo- Spiral

Is the largest of the nerves of the arm. It passes from the
axillary plexus downward, backward, and outward, under the
triceps muscle to the external side of the os humeri. In this
course, it gives off several muscular branches to the different
portions of the triceps. It also frequently gives off a large
branch called spiral cutaneous, which passes downwards on
the outside of the olecranon, to the back of the fore-arm, and
continues to the back of the hand, furnishing many branches
which terminate in the integuments. It then proceeds down-
wards between the supinator radii longus and the brachialis
internus. Immediately after passing the articulation of the
elbow, it divides into two branches, one denominated the Su-
'perficial or Radial, and the other the Profound or Posterior In-
terosseous. The Superficial soon joins the radial artery, and
proceeds downwards, sending branches to the contiguous mus-
cles. In its course about the middle of the arm it passes
beneath and across the tendon of the supinator longus, and
proceeds between it and the tendon of the extensor carpi radi-
alis longior ; it soon after divides into two branches, which are
principally distributed to the thumb and fore-finger, and also
to the integuments. — In the middle third of the arm only is this
branch in relation with the radial artery ; it is there found
lying to the outer side of the vessel. —

The Profound branch pierces the supinator brevis muscle,
proceeds to the back of the fore-arm under the radial extensor,
and continues to the back of the wrist and hand. In this
course it divides into two branches, which are distributed to
all the muscles on the back of the fore-arm muscles, and the
integuments. — One branch runs down as far as the posterior
part of the wrist joint which it supplies. It there forms a long
gangliform swelling as is common with the nerves which sup-
ply the joints of the extremities. —

The Internal Cutaneus

Is the smallest of the nerves which proceed from the axillary
plexus. It descends in the course of the basilic vein, and very

m. .:■!-'

DORSAL NERVES. 517

near it piercing the brachial aponeurosis about the middle of
the arm. Above the elbow it divides into an Internal branch,
which proceeds over the Basilic Vein, and separates into
branches that pass down on the side of the fore-arm ; and an
External Branch that passes under the Median Basilic Vein,
and continues down on the anterior part of the fore-arm.
— There is a long and delicate nerve usually seen on the inner
side of the one just described, called the nerve of Wrisherg,
or the lesser internal cutaneous. It usually arises from the
common trunk of the last cervical and first dorsal, but is
variable in its origin. It sends branches to the inner and front
side of the arm as far down as the elbow joint. It anastomoses
with the first intercosto-humeral in the axilla, and with the
internal cutaneous, and spiral cutaneous at the elbow. —

The Articular or Circumflex

Nerve proceeds backwards from the plexus, between the
teres major and minor, and passes nearly around the body of
the OS humeri with the posterior circumflex artery, at a small
distance below the head of the bone. It is distributed to the con-
tiguous muscles, viz. the subscapularis, teres minor and major,
latissimus dorsi and deltoid, and to the articulation ; but its prin-
cipal branches terminate in the deltoid muscle. — Some branches
pierce the deltoid, become cutaneous and are distributed to the
integuments of the shoulder. —

The Dorsal Nerves

Proceed from the cavity of the spine between the dorsal ver-
tebrae. They are sometimes called Intercostals, because their
anterior branches pass between the ribs, like the blood-vessels
of that name. There are twelve pairs of them, and they are
named numerically, beginning from above.

These nerves proceed from the medulla spinalis by two
fasciculi of fibres — one from each of its lateral portions — the
posterior fasciculus is the largest. After passing through the
lateral foramen and the dura mater, a ganglion is formed by
the posterior fasciculus : the anterior fasciculus unites to the
VOL. II. 44

518 LUMBAR NERVES.

posterior just beyond the ganglion so as to form a single nerve
which ahnost immediately divides into an anterior and a pos-
terior branch, of which the anterior is the largest.

The posterior branch proceeds backwards, and is distributed
to the muscles of the back. The anterior branch passes towards
the angle of the rib, in contact with the pleura. Soon after its
orio-in, this anterior branch sends off two ramifications which
unite to the intercostal nerve, at the ganglion ; it then proceeds
forwards with the blood-vessels, between the internal and ex-
ternal intercostal muscles, in the groove near the lower margin
of the ribs ; and terminates on the anterior part of the thorax.
In its course it sends branches, not only to the intercostal mus-
cles and pleura, but to the other muscles and the integuments of
the thorax.

Some of the dorsal nerves differ from the others, as to the
ramifications which they send off.

The first nerve, of this order, joins the lower cervical nerves
in the axillary plexus ; but it sends off the ramifications to the
sympathetic, and also a branch, which passes under the first rib
like the other dorsal nerves.

The second nerve sends off a branch, which passes through
the external intercostal muscle into the axilla, and combines
there with the lesser internal cutaneous nerve, (or nerve of
Wrisberg) being distributed with it to the integuments of the
internal and posterior part of the arm. — It is sometimes larger
than usual and supplies the place of the nerve of Wrisberg. —

The third dorsal nerve also sends off a cutaneous branch,
which is distributed to the axilla and the back part of the arm.

These cutaneous branches of the second and third dorsal
nerves, are called Intercosto-hiancral nerves.

The lower dorsal nerves supply the muscles and integuments
of the abdomen.

Of the Lumbar Nerves.

There are five pairs of these nerves. The first of them
passes off between the first and second of the lumbar vertebras,
and the others succeed regularly ; so that the last pair is situated
between the last lumbar vertebra and the sacrum.

LUMBAR NERVES. 519

The first lumbar nerves arise from the medulla spinalis, before
it forms the cauda equina ; the other four pair are formed by the
Cauda equina.

They commence from the medulla by anterior and posterior
fasciculi, which are united just beyond the ganglion formed on
the posterior root. From this union anterior and posterior
branches go off, which are very different in size, the anterior
being the largest.

The posterior branches are distributed to the muscles of the
back. The anterior send branches to the ganglions of the sym-
pathetic nerve, and also communicate with each other to form
the Lumbar Plexus, which is situated on the lateral parts of the
bodies of the lumbar vertebrae, before their transverse processes,
and supplies nerves to the muscles of the thigh.

The First Lumbar Nerve

Is connected, by its anterior branch, to the last dorsal and the
second lumbar. From the same branch two ramifications go off
to the Quadratus Lumborum, and obliquely across that muscle,
to the lower part of the abdominal muscles near the spine of the
ilium.

— These are called the superior and inferior musculo-cutaneous ,
external spermatic, or ilio-scrotal nerves. The superior traverses
the transversalis muscle near the crest of the ilium, and divides
into two branches. One called the abdominal, passes across the
abdomen to the rectus muscle, to which and the integument
covering it, it is distributed ; the other branch named scrotal,
passes out at the external abdominal ring, and is distributed to
the skin of the groin and that covering the os pubis, to the scro-
tum of the male, and the labium externum of the female. The
inferior musculo-cutaneous is smaller than the superior, but has
nearly a similar distribution : it anastomoses with the latter near
the anterior superior spine of the ilium. —

The Second Lumbar Nerve,

— Sends off a branch called the External Cutaneous, which
perforates the outer border of the psoas near its middle, crosses

520

LUMBAR NERVES.

the iliacus internus muscle, and runs be-
neath the fascia covering it, to reach the
interval between the anterior and superior
spinous processes of the ilium, where it
passes from the pelvis underneath Pou-
part's ligament. About two inches be-
low this point it pierces the fascia lata,
and is distributed to the integuments of
the outer and posterior part of the thigh,
the anterior filaments which it gives off
reaching as far down as the knee. This
external cutaneous is sometimes sent off
from the anterior crural.
— Another branch is sent off from the
second lumbar called the External Sper-
matic, or genito-crural, which perforates
the front of the psoas muscle and the fas-
cia covering it. It descends along the
inner border of this muscle till it meets
with the external iliac artery near Pou-
part's ligament, where it divides into a
spermatic or genital, and a crural branch.
The spermatic branch passes out from the
abdomen with the cord and is distributed
on its cremasteric investment. In the
female it sends branches to the round lig-
ament. The crural or femoral branch runs
out through the sheath of the vessels, just
at the outer margin of the femoral artery,
pierces the sheath and is spent upon the
integuments of the inguinal region, or
upper third of the front of the thigh.f —

* A diagram showing the lumbar and sacral plexuses, with the nerves of the
lower extremity. 1. The five lumbar nerves ; which, with a branch from the
last dorsal constitutes the lumbar plexus. 2. The four upper sacral nerves ;
which, with the last lumbar, form the sacral plexus. 3. The two musculo-
cutaneous nerves, branches of the first lumbar nerve. 4. The external cuta-
neous nerves. 5. The genito-crural nerve. 6. The crural or femoral nerve.
7. Its muscular branches. 8. Its cutaneous branches, middle cutaneous. 9.

t The external spermatic often comes off from the second lumbar nerve.

LUMBAR NERVES. 521

The Second Lumbar, after sending off these branches,
passes downwards, and joins the Third lumbar nerve. From
this union of the second and third nerves, a branch called the
Cutaneous Medius, which will soon be described, proceeds
downwards.

After sending off this branch, the united trunk of the second
and third joins the Fourth ; and fiom this union is sent off the
Obturator Nerve, which passes through the aperture in the
meoibrane that closes the foramen tbyroideum ; the Crural
Nerve, which passes under Poupart's ligament ; and a third
branch that proceeds downwards, and joins the Fifth lumbar
nerve. The Fifth lumbar nerve, with this accession from
above, descends into the pelvis, and unites with the sacral
nerves, forming a branch called the lumbosacral.

This arrangement of the lumbar nerves constitutes the
Lumbar Plexus, which, as has been already stated furnishes
three nerves to the lower extremity, namely, the Cutaneous
Medius, the Obturator, and the Crural Nerve.

The Cutaneous Medius, which arises from the union of the
second and third nerves, and very frequently from the anterior
crural, as has been already observed, proceeds downwards,
and frequently adheres to the crural nerve, for a short distance,
near Poupart's ligament, but soon leaves it, and ascends on the
inside of the thigh, supplying the integuments as low as the knee.

The Obturator Nerve,

Descends into the pelvis, and passes out of it at the upper
part of the foramen tbyroideum ; proceeding downwards in an
internal direction, to be distributed on the inside of the thigh.

Its descending or saphenous branches. 10. The short saphenous nerve. 11.
The long or internal saphenous. 12. The obturator nerve. 13. The gluteal
nerve ; a branch of the lumbo-sacral nerve. 14. The internal pudic nerve.
15. The lesser ischiatic nerve. 16. The greater ischiatic nerve. 17, The pop-
liteal nerve. 18. The peroneal nerve. 19. The muscular branches of the pop-
liteal. 20. The posterior tibial nerve ; dividing at 21, into the two plantar
nerves. 22. The external saphenous nerve, formed by the union of the com-
municans poplitei and communicans peronei. 23. The anterior tibial nerve.
24. The musculo-cutaneous nerve, piercing the deep fascia, and dividing into
two cutaneous brandies, for the supply of the dorsum of the foot.

44*

522 ANTERIOR CRURAL NERVE.

This nerve is generally accompanied by the obturator artery
and vein : the artery being above, and the vein below it.
When it has arrived at the foramen ovale or thyroideum, it
sends off a branch to the internal and external obturator mus-
cle, and, after passing these muscles, divides into two branches,
which are distributed to the muscles on the inside of the thighs,
the adductors, the pectineus, gracilis, &;c.

— From the branch which supplies the adductor brevis, a small
filament is sent to unite with the long saphenous nerve, which
comes from the crural ; the branch to the adductor longus, gives
off the long cutaneous nerve, which after uniting with the short
saphenous nerve, descends to the knee, communicates there with
the long saphenous nerve and is distributed to the skin upon the
inner side of the leg. The branch to the adductor magnus after
piercing this muscle, is called articular as it passes down with
the popliteal artery and pierces the back part of the knee joint,
to be distributed on the synovial membrane — .

The Crural Nerve,

Is situated at first behind, and then on the outside of the
psoas muscle. It passes under Pou part's ligament with the
great femoral vessels, being on the outside of the artery.

It is distributed to the integuments, and also to the muscles
which are situated on the anterior and internal parts of the
thigh. Some of its ramifications go off before it passes under
Poupart's ligament. Of these some muscular branches are
distributed in the psoas, and iliacus internus. Several of them
are superficial and are spent upon the integuments, and are.
therefore, denominated Cutaneous. — They are distinguished
by the terms Cutaneous Anterior, Cutaneous Internus, accord-
ing to their situations, and are distributed to the integuments on
the front and inner portions of the thigh.

The deep-seated branches are the largest. They are prin-
cipally spent upon the muscles on the anterior and the internal
side of the thigh, namely, the four extensors, the adductors,
the pectineus, the sartorius and the gracilis. Among the
nerves coming off from the crural there is one, called the Long

SACRAL NERVES. 523

Saphenous, which has a different destination. It accompanies
the great artery of the thigh to the place where it perforates
the Adductors ; it there separates from the artery, and passes
over the tendon of the Adductors, under the sartorius muscle ;
thence it continues, with the great saphena vein on the inside
of the leg, to the internal ankle ; sending branches to the
integument, in its course. It terminates in skin and cellular
substance on the upper and internal surface of the foot.
— Another branch is generally found coming from the outer
crural called the short saphenous or accessory nerve of the
saphenous. It anastomoses with the obturator and with the
long saphenous nerve. It sends off some cutaneous branches in
the middle of the thigh behind the internal saphena vein, and
distributes filaments to the skin at the inner surface of the knee.
When this nerve is absent its place is supplied by branches
from the long saphenous. —

The Sacral Nerves

Are composed of those cords of the cauda equina which
remain after the formation of the lumbar nerves. They are fre-
quently stated to consist of five or six pairs, four of vv'hich pass
through the foramina of the sacrum and the fifth between the
sacrum and the os coccygis.* The cords of which they are
respectively composed arise by anterior and posterior fasciculi.
When they have arrived opposite to the foramina of the sacrum,
through which they are to pass, a ganglion is formed, at which
they unite ; they then divide into anterior and posterior
branches.! The uppermost of the anterior branches are large,
and pass through the anterior foramina of the sacrum. The
posterior are small, and go through the posterior foramina.

The Posterior Branches are generally spent upon the mus-
cles which lie on the sacrum and posterior parts of the pelvis,
externally.

The anterior branches of the three first nerves send ramifica-
tions to the sympathetic. They unite to each other, and are

* The sixth pair, when they exist, proceed in a groove in the os coccygis.
f The ganglions of the fourth and fifth nerves are extremely small, and not
so near the foramina as those of the others.

5:24 SCIATIC nerve.

joined by the last lumbar nerve, and by a branch of the fourth
sacral, in the formation of the great sciatic nerve. This union
constitutes the Sciatic Plexus.

The anterior branch of the fourth nerve transmits branches
to the sympathetic : it also sometimes sends a branch to the
united nerves above, or the sciatic plexus. It sends branches to
the hypogastric plexus, and to the contiguous muscles.

The fifth and sixth pairs, which are very small, terminate also
in the contiguous muscles and in the integuments.

From the Sciatic plexus, or the nerves which compose it, sev-
eral smaller branches go off. There are generally two which
pass off backwards through the ischlatic notch, and are denomi-
nated Gluteal, as they are distributed to the glutei muscles.
From the lowermost of these a branch descends on the thigh.

The Pudic nerve, which is appropriated to the organs of
generation, also passes off from this plexus, and appears to
consist of fibres which are derived from each of the nerves that
compose it. It proceeds between the sacro-ischiatic ligaments
and divides into two branches — an inferior and a superior. The
inferior passes between the erector penis and the accelerator
urinaj muscles, and is distributed to those muscles, to the bulb of
the urethra and the interior of that canal, to the scrotum and
dartos.

The superior proceeds along the os pubis to the symphysis,
and passes between the bone and the body of the penis to the
dorsum. A considerable branch accompanies the artery on the
dorsum, and terminates by many ramifications, on the glans
penis ; after sending branches in its course to the integuments
generally, and to the prepuce.

In females, the Inferior pudic nerve or perineal proceeds
along the external labia pudendi to the mons veneris, sending off
many ramifications in its course.

The Superior pudic nerve proceeds as in males, alono- the
branch of the pubis to the superior surface of the clitoris, and
terminates principally upon the extremity of that organ.
— A nerve called the Lesser Sciatic, passes out through the
sciatic notch below the pyriformis muscle. It gives off some
muscular branches to the glutei muscles, and two that are

SCIATIC NERVE. 525

cutaneous ; one of these two the pudendaUs longus inferior
(perineal cutaneous) winds round the tuberosity of the ischium
and is distributed to the inner surface of the scrotum, and
the skin on the lower surface of the penis. The other cutane-
ous nerve is called the middle posterior cutaneous and is spent
upon the integuments of the middle and back part of the thigh
and of the leg as far down as the calf. On the leg it forms a
junction with the external saphenous nerve.
— Some muscular branches are sent off likewise from the
sacral plexus to the pyriformis, gemini, and quadratus femoris
muscles. —

The sacral nerves unite in the sciatic plexus to form the
great nerve of the lower extremity, which is next to be de-
scribed.

THE GREAT SCIATIC NERVE

Proceeds from the pelvis through the ischiatic notch, between
the pyramidalis, and the superior gemellus muscle ; it then
passes down to the back part of the thigh, between the tube-
rosity of the ischium and the great trochanter of the os femoris ;
and continues downwards, inclining from within outwards, to
the ham, where it is situated between the tendons of the
semi-tendinosus and semi-membranosus on the internal side,
and the tendon of the biceps on the external. In this course
it sends off branches to the muscles on the posterior part of the
thigh.

As the great nerve passes down the thigh, it sends off ob-
liquely downwards and outwards, a large branch which is
called the Fibular, that passes across the head of the fibula to
the external and anterior part of the leg. The place where
this branch separates from the main nerve is different in dif-
ferent subjects. It continues in contact with it for some dis-
tance, connected only by cellular membrane.

The Fibular or Peroneal Nerve

Proceeds downwards on the inside of the tendon of the
biceps, and crosses obliquely to the outside of the external

526 POPLITEAL NERVE.

head of the gastrocnemius : it then passes inwards between
the peroneus longus muscle and the fibula : and descending
between the muscles on the front of the leg, divides into two
branches, one of which inclines to the exterior side of the leg,
and the other preserves an internal situation. In its course
from the great sciatic nerve to the fibula, it sends off some
superficial ramifications. The two branches into which it
divides, after passing over the fibula, continue downwards.
The Internal or Anterior Tibial goes under the head of the
extensor longus digitorutn to reach the outer side of the ante-
rior tibial artery, and after supplying the muscles on the ante-
rior part of the leg, passes under the annular ligament of the
ankle, at the external side of this artery ; on the upper part of
the foot, it divides into two ramifications, one of which proceeds
forwards near the internal edge of the foot and the other near
the external ; they divide again, and are distributed to the parts
on the upper surface of the foot, one of their ramifications
descending with the continuation of the anterior tibial artery
to the sole of the foot.

The External Branch of the fibular nerve called musculo-
cutaneous, as it proceeds downwards, supplies ramifications to
the contiguous muscles, and passing through the fascia on the
outside of the leg, continues between it and the skin towards
the foot. In this course it generally divides into two branches,
which are spent upon the upper surface of the foot.

The Great Sciatic Nerve, after the fibular nerve leaves It,
continues down the thigh, between the tendons of the flexors,
behind the great blood-vessels, and, of course, exterior to them.

Popliteal.

In the ham, this great nerve takes the name of Popliteal, and
proceeds across the articulation of the knee, between the heads
of the gastrocnemii, to the posterior side of the tibia : here it
passes through the upper portion of the soleus or gastrocnemius
internus, and continues between it and the long flexor of the
toes, near the Posterior Tibial Artery ; descending with that
artery to the hollow of the os calcis. In this situation it has
the name of

DISTRIBUTION OF THE TIBIAL NERVE. 527

Posterior Tibial Nerve.

At the commencement of this course, a small distance below
the internal condyle of theos fetnoris it gives off some muscular
branches to the heads of the gastrocnemius muscle, and one to
the knee joint which pierces the ligament of Winslow ; it sends
off another of considerable size, called the Communicans Tibia,
or Poplitei, or Snphena Externa, which passes down behind the
gastrocnemius, and gradually inclines externally, so that it is
situated on the external edge of the tendo Achillis, soon after
the commencement of that tendon, and proceeds behind the
external ankle, near the outer side of the foot, to the smaller
toes : distributing branches to the contiguous parts. In its course
on the back of the leg, it sends off a branch which unites with
one of the superficial ramifications of the fibular nerve called
Communicans per onei ; the trunk thus formed, descends to the
outer part of the foot.

The Posterior Tibial Nerve, in its course downwards, sends
branches to the contiguous muscles, and a few twigs which form
a species of network on the artery. In the hollow of the os
calcis it sends off a superficial branch to the integuments of the
sole of the foot, which proceeds on the outside of the aponeu-
rosis plantaris : it there also divides into branches, which are
denominated the Internal and External Plantar Nerves.

The Internal Plantar Nerve proceeds forwards, alongside of
the tendon of the long flexor muscle of the great toe, giving
off small branches in its course ; about the middle of the foot
it divides into four branches, one of which proceeds to the inside
of the great toe ; and a second to the angle formed by the great
toe and the toe next to it, where it divides and sends a branch
to the opposite sides of those toes : the other two branches are
distributed in a similar manner, to the succeeding toes. These
digital branches are connected with each other by small ramifi-
cations.

The External Plantar Nerve proceeds with the external
plantar artery towards the external side of the foot, between
the short flexor of the toes and the flexor accessorius. Near

528 COMMENCEMENT OF THE SYMPATHETIC NERVE.

the external edge of the foot, about the posterior end of the
metacarpal bones, it divides into three branches. One pro-
ceeds to the outside of the little toe ; another passes to the
angle between the fourth toe and the little toe, and divides into
branches which are distributed to the corresponding sides of these
toes. The third branch proceeds more deeply in the foot, from
the external towards the internal edge of it, and is spent upon
the deep-seated contiguous muscles.

The Great Sympathetic or Intercostal Nerve.

— The great sympathetic system is characterised by the
greyish color and the softness of its nerves, and the gangli-
form enlargements found upon them in various situations, con-
nected together by intervening cords or nervous filaments.
These ganglia are found in the head, neck, thorax and abdo-
men. Many of them are placed about the viscera and along
the course of the blood-vessels of the trunk and head, having
intercurrent branches, so as to form large centres or plexuses,
from which nerves are distributed to the neighboring organs.
A ganglionated cord composed of a large number of ganglia
and intercurrent trunks, is formed in a line between the head
and OS coccygis, on either side of the spinal column, for the
double purpose of its interchanging filaments with the spinal
nerves as they leave the intervertebral foramina, and commu-
nicating with the sympathetic nervous plexuses placed over the
middle portion of the spine. It communicates with the cerebral
nerves in like manner, at their exit from the cranium, with the
exception of the fourth and sixth, with which it forms junctions
in the cavernous sinus, and the auditory, optic, and olfactory,
with which it is connected at the places of their final distribution.
Although this system does not send out branches as distinct
nervous trunks to the extremities, it nevertheless gives fila-
ments to all the spinal nerves, among the rest those that form
the cervical, lumbar, and sciatic plexuses, and which they
accompany in their distribution. The filaments which go to
the extremities form, however, but a minute portion of this
extensive system. They are not the agents of cerebral sensa-

^^i^^^Mtm^

GENERAL PLAN OF DISTRIBUTION. 529

tlon or voluntary motion, but of that organic sympathy or sen-
sation, and those organic movements, which, to the knowledge
of every one, exists in the viscera of the abdomen, susceptible
of being but little influenced by the will, and which are
mainly concerned in the great processes of digestion, circu-
lation, and nutrition. Hence, from its manner of distribution,
the sympathetic has been called the nervous system of organic
life. The general, though not exclusive route of distribution
of its branches is along the outer surface of the arteries. At
the roots of the greater vessels, the nerves are collected in
such numbers, occasionally intermixed with ganglia, as to
form plexuses, which take the names of the arteries ; as the
hepatic, the gastric, mesenteric plexus, &;c. For this reason
the sympathetic has been called by some, the vascular system
of nerves. The term of sympathetic, which is the more gene-
rally used, appears to be derived from the fact of this system
associating the different organs in separate sets or apparatuses,
so that they are enabled to work together in their healthy
condition, to the certain fulfilment of a common object. Thus
we have the stomach, the liver, the pancreas, the intestines,
and possibly the spleen, forming a combination for the purposes
of digestion ; the kidneys, the ureters, and the bladder,
for the removal of the urine : and this association is main-
tained through the agency of the different central plexuses or
ganglia, from which branches are sent to supply these different
organs.

— The sympathetic nervous system not only emits branches of
communication to the cerebro-spinal, but likewise receives
filaments from the latter in return, which are intermingled
with and distributed to the organs along with its own parti-
cular class of nervous fibres. This is especially the case in
regard to the neck, the thorax, and the pelvis, where the
voluntary and involuntary movements, though each at times
exercised alone, are nevertheless much mixed and inter-
mingled.

— But the viscera of the abdomen in which voluntary cerebral
power of all other parts can be least exerted, receive their
VOL. II. 45

530 GREAT SYMPATHETIC OR INTERCOSTAL NERVE.

supply, with but very (ew exceptions, solely from the great
sympathetic system.

— It is not now considered proper to apply the term origin, to
the anastomosis which the sympathetic forms with the fifth
and sixth nerves in the carotid canal, an anastomosis which
has nothing in it different from the other junctions of this sys-
tem with the cerebro-spinal nerves. Later researches have
proved likewise that the sympathetic ascends much higher in
the head, where is found in fact six sympathetic ganglia, each
one forming a little centre from which branches proceed in
various directions, especially about the blood-vessels. These
are all connected more or less directly with each other, with
the cerebral nerves, and with the superior cervical ganglion of
the sympathetic below, to the ascending nerves of which they
seem to be superadded.

— Of these sympathetic ganglia, we have 1st. As the upper-
most, the ganglion of JRibes* situated in the cavity of the
cranium on the anterior communicating artery of the brain,
2d. The ciliary or lenticular ganglion, placed on the outer side
of the optic nerve just after its entry into the orbit. 3d. The
naso-palatine ganglion, or ganglion of Cloquet, placed in
the foramen incisivum of the upper maxillary bone. 4. The
spheno-palatine ganglion, or the ganglion of Meckel, located
in the spheno-maxillary fissure. 5. The sub-maxillary ganglion,
situated on the outer side of the capsule of the sub-maxillary
salivary gland ; and 6th, The auditory ganglion, or ganglion
of Arnold, found just at the lower margin of the foramen
ovale of the sphenoid bone, and which has been described at
page 476. To these might be added a ganglion that is occa-
sionally found at the upper opening of the carotid canal on the
surface of the carotid artery, which has been named the carotid
ganglion, or the ganglion of Laumonier, from the anatomist
who first described it.f But in the far greater number of cases,
in which I have looked for this ganglion, it consisted of a but
slight elongated expansion of one of the nerves, which assist

* So named from the anatomist who discovered it.

f As it is found when present at the top of the carotid canal and by the side
of the cavernous sinus, it has also received the name of cavernous ganglion.

SYMPATHETIC GANGLIA IN THE HEAD. 531

in forming the carotid plexus, found at this point. The man-
ner in which these ganglia communicate one with another and
with the superior cervical is well shown in fig. 214.
— The branches that are there seen connected with the upper
part of the superior cervical ganglion, and which are described
as descending from the carotid canal by Dr. Wistar, are now
believed to be the proper ascending branches of the superior
cervical ganglion itself, intended to place the important organs
which are found in the cranium and face, in sympathetic con-
nection with the great centres of organic life, the heart and
the stomach.

— From the carotid plexus, filaments ascend along the branches
of the carotid artery ; one of these ascending with the anterior
artery of the cerebrum, meets its fellow of the opposite side
on the anterior communicating artery, and on it is formed the
ganglion of Ribes ; thus constituting at their superior termina-
tions an anastomosis of the sympathetic nerves of either side,
as is found to take place below at their inferior extremity, on
the front of the os coccygis.

— A small branch is also seen -fig. 214, directed forwards and
upwards to communicate with the ophthalmic or ciliary-
ganglion. This ganglion as before described, page 490, has
branches also passing in the orbit between it, and the motor
oculi and the nasal branch of the fifth pair of cerebral nerves.
From the ciliary ganglion pass off nine or ten ciliary nerves,
which pierce the sclerotic coat at the back part of the ball, and
are distributed to the tunics of the eye ; one branch, according
to Tiedemann, accompanying the centralis retinae artery to the
interior of the eyeball.

— From the carotid plexus, a communication is made forwards
and downwards with the spheno-palatine ganglion, which is
the largest of all the sympathetic ganglia of the head.
— On one of the nasal branches sent inwards and forwards
from the ganglion, called the naso-palatine, is found the
ganglion of Cloquet, which is then put in connection with the
sympathetic nerve, through the medium of the ganglion of
Meckel, or spheno-palatine. — But these ganglia have already

532 UPPER TERMINATION OF THE SYMPATHETIC NERVE.

been described in their connection with the nerves of the
head.

— The submaxillary ganglion is of small size, and sends its
branches principally to the ducts of the submaxillary and sub-

Fig. 214.*

lingual salivary glands, and some few which anastomose with
the surrounding branches of the lingual and facial nerves. It is

* The cranial ganglion of the sympathetic nerve. 1. The ganglion of Eibes.
2. The filament by which it communicates with the carotid plexus (3). 4. The
ciliary or lenticular ganglion, giving ofl" ciliary branches for the supply of the
globe of the eye. 5. Part of the inferior division of the third nerve, receiving
a short thick branch from the ganglion. 6. Part of the nasal nerve, receiving
a longer branch from the ganglion. 7. A slender filament sent directly back-
wards from the ganglion to the sympathetic branches in the cavernous sinus.
8. Part of the sixth nerve in the cavernous sinus, receiving two branches from
the carotid plexus. 9. Meckel's ganglion (spheno palatine.) 10. Its ascending
branches, communicating with the superior maxillary nerve. 11. Its descend-
ing branches, the posterior palatine. 12. Its anterior branches, spheno-palatine
or nasal. 13. The naso-palatine branch, one of the nasal branches. * The
swelling which Cloquet imagines to be a ganglion. 14. The posterior branch
of the ganglion, the Vidian nerve. 15. Its carotid branch communicating with
the carotid plexus. 16. Its petrosal branch, joining the angular bend of the
facial nerve. 17. The facial nerve. 18. The chorda tympani nerve, which
descends to join the gustatory nerve. 19. The gustatory nerve. 20. The sub-
maxillary ganglion, receiving the chorda tympani nerve from the gustatory.
21. The superior cervical ganglion of the sympathetic.

SYMPATHETIC NERVE. CERVICAL GANGLIA. 533

placed in connection with the ganghon of IMeckel, and through
that with the other gangha and the carotid plexus, by means
of the superficial petrous or Vidian nerve, which, as already
described, after having become the chorda iympani, terminates
in the submaxillary ganglion. — The auditory ganglion has been
already fully described, as well as its branches of communication
with the surrounding parts at page 476. —

The sympathetic system has been said to commence in the
cranium with those small ramifications of the pterygoid branch
of the upper maxillary nerve, and of the sixth pair, which ac-
company the carotid artery through the canal in the petrous
portion of the temporal bone. These small nerves form a net-
work which surrounds the artery in the canal and gives rise to
the incipient sympathetic, a small cord which passes down close
to the nerves of the eighth and ninth pairs of the neck. Oppo-
site to the second cervical vertebra, this nerve is swelled or di-
lated, so as to form a body of a light red color, which is more
than an inch in length, and has the form of two cones united to
each other at their bases. This is the Superior Cervical Gang-
lion of the Sympathetic Nerve, and from it the nerve descends,
behind the Par Vagum, on the front part of the neck.

This ganglion receives twigs from the first, second, third, and
fourth pairs of cervical nerves, and also from the eighth and
ninth nerves of the head. It sends off several twigs, which
pass behind the carotid artery at its bifurcation and are joined
by twigs of the Portia Dura and the Glosso-Pharyngeal nerves.
From these united twigs proceed very small ramifications,
which accompany several branches of the external carotid
artery, and some of them pass down with the Common Ca-
rotid.

This superior ganglion also furnishes small twigs which
accompany the Glosso-Pharyngeal to the tongue and pharynx.
Sometimes a twig from it passes on the back part of the thy-
roid gland to communicate with the recurrent nerve. From
this ganglion go off some small branches, which, uniting with
others from the superior laryngeal nerves, form the superior or
superficial cardiac nerve, which will be soon described.
45*

534 SYMPATHETIC NERVE. CERVICAL GANGLIA.

The trunk of the Sympathetic Nerve descends, on the front of
the neck, from this ganglion, as has been ah-eady stated. In
its course it receives very small twigs from the fourth and 6fth
cervical nerves', and sends some very small twigs which appear
to go to the oesophagus, and some which unite to the laryngeal
nerve and go to the thyroid gland. Some twigs which are
larger proceed from it into the thorax, and go to the cardiac
plexus hereafter to be described.

Opposite to the interval between the fifth and sixth cervical
vertebrae it forms another ganglion, of an irregular shape, much
smaller than the first. This ganglion, in different subjects,
differs in size as well as in several other respects. Sometimes
it is entirely wanting, and sometimes it is doubled. It is denom-
inated the Middle Cervical or Thyroid Ganglion. When the
fourth, fifth, and sixth cervical nerves do not send ramifications
to the sympathetic nerve, this ganglion receives twigs from
them.

The Middle Cervical, or Thyroid Ganglion sends many
ramifications downwards. Some of them enter the thorax
and contribute to the formation of the Cardiac Plexus ; others
accompany the inferior thyroid artery, and, with twigs from
the recurrent nerve, form a plexus which extends towards the
thyroid gland. Some proceed downwards before, and others
behind, the subclavian artery, to the next ganglion ; among
them is generally one which may be regarded as the trunk of
the Sympathetic.

This third Ganglion is denominated the Inferior Cervical,
or the First Thoracic. It is almost constantly found in the
same situation, viz. between the transverse process of the last
cervical vertebra and the head of the first rib, and is partly
covered by the origin of the vertebral artery. It is generally
larger than the middle ganglion. It receives branches from
the sixth and seventh cervical, and the two first dorsal nerves.
Ramifications pass from it to the par vagum and recurrent
nerve, and also to the cardiac and pulmonary plexus.

From this ganglion the Sympathetic Nerve proceeds down-
wards on the side of the spine, as will be described hereafter.

CARDIAC NERVES. CARDIAC PLEXUS. 535

The Nerves of the Heart,

Being derived from branches which have already been men-
tioned, are now to be described.

They arise principally from an arrangement of nerves deno-
minated the Cardiac Plexus, or Plexuses, which is situated above
the curve of the aorta, and extends, on the posterior side of it,
from the root of the arteria innominata to the bifurcation of the
pulmonary artery. This plexus is composed of nerves which
are principally formed by the union of small ramifications that
are derived fiom the three above mentioned ganglions of the
Sympathetic Nerve, and the nerve itself; and also from the Par
Vagum, and some of its branches.

These nerves are denominated the Cardiac. They descend
on their respective sides of the neck, but are somewhat different
on the different sides. On the right side three nerves have been
described as particularly entitled to this name, and on the left
side but two.

The first on the right side is denominated Superior, or Su-
perficial Cardiac Nerve. It generally arises by several fine
threads, which unite into one delicate cord that passes down
by the side of the common carotid. When it has arrived on a
line with the middle ganglion, it sends a twig to the thyroid
plexus, and another that communicates with a twig from the
par vagum, which continues downwards on the carotid artery.
After passing beyond the ganglion, it divides into several
branches, which unite themselves to branches of the recurrent
nerve that are going to the middle ganglion.

The second, which is denominated the Middle Cardiac, the
Great Cardiac, or the Deep Cardiac, is the largest of the three.
It arises from the Middle Cervical, or Thyroid Ganglion, by
five or six fine fibrils, which finally form one, that passes
before and across the subclavian ; and at that place, as well as
lower down, it receives twigs from the par vagum: below this,
it is joined by a considerable twig from the recurrent, and ter-
minates in the Cardiac Plexus, to which it contributes largely.

The third cardiac nerve of the right side is called the Infe-

536 CARDIAC NERVES.

rior, or the Small Cardiac Nerve. It originates from the
third, or lower cervical ganglion, by many fibrils which unite
into a smaller number that form a plexus. It crosses behind
the subclavian, and proceeds on the outside of the arteria inno-
minata to the curve of the aorta ; continuing between it and
the pulmonary artery, to the anterior coronary plexus. In this
course it receives several fibres from the recurrent and the par
vagum.

On the left side the first cardiac nerve arises from the upper
ganglion. The second derives its origin from the two lower
ganglions.

The left superior or superficial cardiac nerve arises like the
right, by many distinct fibres, and proceeds downwards in the
same way. It descends between the carotid and the subcla-
vian, and when it has arrived at the place where they origi-
nate from the aorta, it divides into a great number of small
ramifications. Some pass before the aorta, either to join the
branches of the inferior cardiac, or to unite with the cardiac
branches of the left nerve of the par vagum. The others pro-
ceed behind the aorta, and enter into the common cardiac
plexus.

The second cardiac nerve of the left side may be called the
Great Left Cardiac, and has a double origin, as above men-
tioned. The principal branch in its composition arises from
the lowest cervical ganglion, and passes behind the transverse
portion of the subclavian artery. Where the inferior thyroid
artery arises from the subclavian, this branch receives a consider-
able number of ramifications, which arise from the upper gang-
lion, and are interwoven with each other before they unite to it.
It passes behind the curve of the aorta, and terminates in the
great cardiac plexus, which it particularly contributes to form.
Here it is joined by many fibres from the par vagum.

The Cardiac Plexus

Is situated principally behind the curve of the aorta, at a
small distance above the heart. It commences as high as the

CARDIAC PLEXUS. 537

origin of the arteria innominata, and extends downwards to the
bifurcation of the pulmonary artery.

As has been ah-eady mentioned, it is principally composed of
branches from the middle cardiac nerve of the right side, and
the inferior cardiac nerve of the left ; but it receives branches
from the superior cardiac of the left, and sometimes of the right
side. Some fibres of the inferior cardiac of the right are also
united to it.

Many branches proceed from this plexus.

A sniall number pass upon the aorta, and seem to enter into
its texture.*

Some of them also combine with the ramifications of the Par
Vagiim in the anterior pulmonary plexus.

The majority proceed to the basis of the heart, near the origin
of the pulmonary artery and the aorta, and constitute the 'proper
nerves of that organ. They accompany the coronary arteries,
and are so arranged around them that, by some anatomists, they
have been said to form plexuses, which have been denominated
Coronary.

The Sympathetic Nerve, as has been stated above, proceeds
from the ganglion, called the Lower Cervical, or the First Tho-
racic, before the neck of the first rib. It continues to descend,
in the same direction, along the spine, exterior to the pleura, to
the inferior part of the thorax. Near the head of each rib it
forms a ganglion, which unites with the intercostal nerve behind
it, by two branches, and thus forms an indirect communication
with the medulla spinalis.

From several of the uppermost of these ganglions small twigs
proceed to the pulmonary plexus, and also to the great trunk of
the aorta, below the curve forming a species of net-work, or
plexus upon it.

From the ganglions near the heads of the fifth and sixth
ribs, and from four or five of the ganglions which succeed
them, small nerves arise, which proceed downwards on the

* It has been asserted that some of the anatomists of Paris have traced these
nerves on the aorta, to a great distance from the heart.

538 SPLANCHNIC NERVES. SEMILUNAR GANGLION.

sides of the bodies of the vertebrae, and unite into one trunk
that is denominated the Splanchnic Nerve, because it is distri-
buted to the viscera of the abdomen. — This nerve proceeds be-
hind the crus of the diaphragm, on its respective side, into the
abdomen. A second and smaller nerve, of the same destina-
tion, called the lesser Splanchnic Nerve, arises lower down, from
two or three of the lowermost dorsal ganglions, and penetrates
separately into the cavity of the abdomen : it then generally
divides into two branches, one of which unites to the great
splanchnic nerve, and the other proceeds to the renal plexus
soon to be described.

As soon as the great splanchnic nerve has entered the abdo-
men, it divides into many branches, which commonly form small
ganglions on each side of the coeliac artery, but above it. These
ganglions are generally contiguous : but sometimes they are at
a small distance from each other, and united by nerves. They
are, however, commonly spoken of as one, and called the Semi-
lunar Ganglion. They are of irregular forms, and very different
from each other in size, as well as form. Those formed by the
splanchnic nerve on one side are sometimes different from those
on the other.

From this assemblage of ganglions proceed many small nerves,
which are woven together so as to form a network denominated
the Solar Plexus.

This plexus is situated anterior to the spine and the crura of
the diaphragm, behind the stomach and above the pancreas ;
and is extended upon the coeliac and superior mesenteric arte-
ries. Some ramifications from the par vagum and the phrenic
also join it.

•The lower part of the solar plexus, which surrounds more
immediately the coeliac artery, is termed the Coeliac Plexus.
From it networks of nerves extend upon the great branches of
the artery to the organs to which they go.

They extend to the stomach, (although it is supplied by the
par vagum,) along the superior coronary or gastric branch of
the coeliac ; and the fibres in their composition being spread

CffiLIAC, MESENTERIC, AND RENAL PLEXUSES. 539

upon the coats of the stomach, unite with the branches of the
par vagum, which are also spread upon them.

A similar net-work, denominated the Hepatic Plexus, extends
upon the Hepatic Artery, and from it to the Vena Portarum ;
and accompanies those vessels into the substance of the
liver. It also sends branches to the biliary duct and gall-
bladder ; to the stomach by the arteria gastrica dextra ; and to
the omentum.

The Splenic Artery is invested by a similar but smaller ar-
rangement of nerves, denominated the Splenic Plexus. In its
course to the spleen, this plexus sends some nerves to the
pancreas ; and also to the stomach and omentum, with the
left gastric artery.

The superior mesenteric artery is surrounded by a network,
which extends to it directly from the solar plexus, and is the
largest of all which proceed from that plexus. The Mesenteric
Plexus at first nearly surrounds the artery, and proceeds with
it between the lamina of the mesentery. In this course it
sends branches, with the arteria colica dextra, to the transverse
portion of the colon. Between the lamina of the mesentery,
it sends ramifications with all the branches of the artery, to
the small intestines generally ; to the coecum, and the riohx
portion of the colon, as well as to the mesenteric glands.

From the lower part of the solar plexus a network proceeds,
on the front of the aorta, to the inferior mesenteric artery, and
surrounds it. Nerves from this plexus accompany the artery
to the left portion of the colon and the rectum. Some
of their ramifications combine with those of the hypogastric
plexus.

The Emulgent Artery is attended by nerves, which are
arranged like a network on its anterior and posterior surfaces,
and are denominated the Renal Plexus. They are derived
from the solar plexus, and frequently contain small ganglions.
They proceed with the artery to the fissure of the kidney, and
are distributed with its different ramifications, in the substance
of the organ.

540 SPERMATIC AND HYPOGASTRIC PLEXUSES.

Some branches pass from them to the renal gland with the
capsular artery.

Before the renal plexus arrives at the kidney, it sends off,
from its inferior part, some new fibres, which, after joining
some others from one of the lumbar nerves, accompany the
spermatic arteries, and are, therefore, called the Spermatic
Plexus. In the male, these fibres proceed through the abdomi-
nal ring, and many of them go to the testis, but they are
followed with great difficulty, on account of their small size.

In the female, they go to the ovary and the Fallopian
tubes.

From the great plexuses above, a small network continues
downwards on the aorta, receiving fibres from the intercostals
on each side ; at the great bifurcation of the aorta it divides,
and is joined on each side by many ramifications from the
third lumbar nerves, which thus form a plexus of considerable
extent, that sends nerves to the bladder, rectum, and vesiculae
serninales in males ; and to the uterus and vagina, as well
as the bladder and rectum, in females.* This is called the
Hypogastric Plexus.

The plexuses above mentioned are derived from the
splanchnic nerve, which come off from the Sympathetic in the
thorax.

The Sympathetic Nerve, after giving off the lesser splanch-
nic, is diminished in size, and approaches nearer to the bodies
of the vertebrae. It passes through the crura of the diaphragm,
and then proceeds forwards and downwards upon the spine,
between the tendinous crura of the diaphragm and the psoas
muscle ; near the vena cava on the right side, and the aorta on
the left. In this course, it generally receives one or two small
cords from the anterior branch of each of the lumbar nerves ;
these cords proceed downwards and forwards, between the

* Although the testicle receives nerves which are derived from the sympa-
thetic, the penis and other external parts of the organs of generation do not to
much extent : the nerves which accompany the pudic artery being derived from
those which unite to form the great sciatic.

^^;»^M^'^^^'>iv;* :>,^,^Jto«^

THE GANGLIA. 541

bodies of the vertebrae and the psoas muscle, and a ganglion is
generally formed at the place where they join the nerve.

In its descent on the lumbar vertebrae, the sympathetic sends
off several nerves that unite to the network which descends on
the aorta from the plexus above. After passing over the lum-
bar vertebrae, it descends into the pelvis, close to the sacrum, on
the inner side of the great foramina : here it also forms gang-
lions and communicates with the sacral nerves, and likewise with
the hypogastric plexus. It terminates on the os coccygis, where
its minute fibres join those of the opposite side, and form a gang-
lion at their place of junction, called the coccygeal ganglion or
ganglion impar.

VOL. II. 46

542 GENERAL ANATOMY OF THE NERVOUS SYSTEM.

CHAPTER XVI.

GENERAL ANATOMY OF THE NERVOUS SYSTEM.

— In man, and animals nearest him in the scale of organi-
zation, the nervous system, by its bulk and general distribution,
no less than by the important functions it executes, forms a
very prominent part in the constitution of the body. So early
as the time of Herophilus, who flourished nearly three centuries
before the commencement of the Christian era, the connexion
of the nerves with the brain had been discovered ; as well as
the fact that these parts were to be regarded as the instruments
of sensation and motion. In the sixth century, the idea was
also entertained by Galen that there was some specific differ-
ences among the nerves. He held that the nerves of sensation
originated in the brain, and those of motion, in the spinal
cord. Closely connected, as it was found to be, with the phe-
nomena of life, the nervous system has been, since the com-
mencement of the seventeenth century, a subject of much re-
search among anatomists; but, from its being the most delicate
and complicated in its structure of all the tissues of the body, it
has necessarily required extremely careful and oft repeated ex-
amination, to arrive at any accuracy in regard to its structure.
The progress made in its investigation has consequently been
slow. Comparative anatomy has lent its aid to the elucidation
of nervous structure. One after another, in the downward grade
of animals, have been found provided with nervous centres and
nervous cords, and the recent observations of Tiedemann, Ehren-
berg, Remak, etc., have rendered it extremely doubtful that any
animal exists, without a nervous system properly proportioned
to the force and vitality of its vital actions.
— The nervous structure of man and many of the inferior
animals, is found disposed in masses, as in the brain and spinal
marrow ; rolled up in the form of round cords, called nerves,
which branch in every direction through the body ; and as
small knots, or ganglia, which are developed in the course, or at

THE CINERITI0U3 AND MEDULLARY NEURINE. 543

the origin of the nerves. Though thus diversified in its mode of
disposition about the body, the nervous substance, or neurine, as
it is now more appropriately called, is susceptible of being divided
from its physical qualities and difference of functions, into two
kinds, the cineriiious and medullary.

Of the Cineriiious Neurine.

— The cineriiious neurine, substantia cinerea, has as the term
imports, derived its name from its gray or ash color, and is
soft and pulpy. It is found only in the brain and spinal mar-
row, and in the ganglia of the nerves.* It forms the central
part of the medulla spinalis, and the portion of it lodged in that
position, has received the name of the nucleus of the spinal
marrow. It is found also, in the central parts of the cerebrum,
the cer-ebellum, the crura cerebri, the pons varolii and the
medulla oblongata. It forms, besides, the whole of tbe outer
covering of the cerebrum and cerebellum, existing there in the
form of a layer, a line to a line and a half in thickness, dipping
down between and covering the bases and sides of the convo-
lutions of the cerebrum, as well as the horizontal layers of the
cerebellum, and thus amplifying the superficies of those organs
to three or four times that of the interior surface of the walls
of the cranium. From the external position it occupies in
these organs, it has been called, though very inappropriately,
the cortical substance of the brain. It is very abundantly
supplied with blood-vessels, which exist in it in the form of
meshes of capillary vessels conveying red blood, and pervade
its whole substance, so as to render it, if not the most, one of
the most, vascular portions of the body. This great vascularity
appears to be the cause of the grayish brown color from which
the name of cincritious has been derived. It is of a darker
color in man than any other animal, and is found gradually
to become paler, as we descend in our investigations, along
the animal scale. Some of the central deposits of cineriiious

* The microscopical observations of Kemak and Mailer, have shown it to
exist occasionally in the nerves of the sympathetic, and in some of the enceph-
alic nerves of the cerebro-spinal system. But in such cases, the nerves con-
taining it are devoted wholly to the organic functions, and may be considered
rather as elongated funicular ganglia.

544 CINERITIOUS GLOBULES.

matter in the interior of the brain, are of a deeper color than
that covering the surface : that in the crura cerebri is so dark
as to have received from Soemmering* the name of locus niger ;
that of the corpus dentatum of the cerebellum is yellowish.
— A striking peculiarity in the mode of deposition of the cine-
ritious matter, is its distribution in detached "portions. Thus, the
cineritious coatings of the cerebrum and cerebellum, have no
direct continuity with each other ; nor have the cineritious
deposits in the interior of these organs, any communication
except through the medium of the white or medullary portioa
of the brain, with that of the spinal marrow, or of the different
ganglia upon the trunks of the nerves.

— The cineritious matter, when examined with the microscope,
either in the brain, spinal marrow, or ganglia, is found composed
of cellular globules or granules varying from j^^g to 55^5 part of
an inch in diameter, having no distinct linear arrangement, but
embraced in meshes of capillary vessels and granular cellular
tissue, which serve as capsule about them. These globules form
a granular mass or layer spread over and amidst the medullary
matter. Each of these globules, according to Valentine, con-
tains two nuclei, one concentric and within the other, the smaller
and interior one being called the nucleolus. It has long been
suspected that the globules of cineritious substance, were in
some way connected with the termination or origin of the ner-
vous fibrils, as the bellies of the muscles are with their tendons.
Gall considered the cineritious substance as the matrix or genera-
tor of the white fibres. But this assertion is unfounded, if it
be used to imply more than a close and inseparable relationship
between the two sets of fibres. — The question of their connec-
tion may now be considered as nearly decided. Remak and
Muller,f both assert, that in their microscopical investigations
they have seen tooth-like white fibres coming off from the sur-
face of the cineritious globules. In the ganglion, Remak suc-

* This variety of color in different portions of the cineritious substance, is not
peculiar to man. Cuvier found it to be the case in regard to the ganglia of some
of the lower animals. In the Helices he found the ganglia red, and in the
Aplysia, black, while the nerves were white. There is in some places pigmen-
tary matter deposited in the gray substance even in man, as in the locics niger.

t Mailer's Physiology, Part 3, vol, i., Bennet's Translatio--,

STRUCTURE OF MEDULLARY NEURINE. 545

ceeded in isolating these tooth-like processes to an extent of
many times their diameter, so as to be enabled to observe their
similarity to the primitive gray fibres of the ganglionic nerves.
There is therefore some reason to believe that this is the mode
of origin of many of the ganglionic nerves — that is, those which
exclusively belong to the organic functions, — and that many of
the cerebro-spinal nervous filaments originate in the same way,
especially those which have latterly been denominated by Mr.
Marshall Hall the excito-motory, or with more propriety, the
reflex system of nerves.

Of the Medullary Neurine.

— The medullary neurine, substantia medullaris, forms a large
portion of the interior of the cerebrum and cerebellum, and has
received its name from its central position in these parts, like
that of the medulla or marrow within the cavity of a bone.
But this term is far from being generally appropriate, for the
medullary nervous substance, is found forming the exterior of
the crura cerebri and cerebelli, the pons varolii, medulla oblongata
and spinal marrow, and constitutes very nearly the entire
structure of the nervous cords. But the term, introduced at an
early period, has become so hallowed by usage, as to be con-
sidered classical and is very generally employed. The medulla-
ry nervous substance in its natural state is every where of a
white or cream color. Unlike the cineritious substance of the
brain, the medullary is apparently placed no where in detached
masses ; the nervous cords are continuous with the medullary
portion of the spinal marrow and this again with the medullary
masses of the encephalon. The ganglia themselves being no
interruption to the course of the nervous cords.
— Unlike the cineritious matter also, the medullary is every
where found to be fibrous ; a fact that was first demonstrated
by Vieussens in 1684,* and which is now as generally admitted
as any other truth in anatomy and physiology, and may be shown
convincingly on a hardened brain to the most sceptical inquirer.
— The mode adopted by Vieussens in order to display these
medullary fibres, was that of scraping its surface in the recent
* Vieussens, Neurographia Universalis.

46*

546

PRIMITIVE MEDULLARY NEURINE.

State ; the same adopted by Gall, Spiirzhelm, Reil, and others,
in the present century, by whom the anatomy of the brain,
though still very imperfect, has been greatly advanced.
— In the medullary neurine, when examined with the micro-
scope, no globules of considerable size and detached distribu-
tion, like those of the gray matter, are ever met with. Whether
examined in the brain, spinal marrow, or white nerves, it pre-
sents, when separated into its ultimate elements, the appearance
of parallel white fibres (studded here and there with minute
nerve cells,) the diameter of which, according to R. Wagner, is,
in the nervous cords, the J^th part of a line.

Fig. 215.* — These primitive fibres are simple

threads, formed of a cylindrical sheath,
filled with the nervous matter. This
nervous matter or neurine, forms during
ql life a transparent colorless oil-like fluid.

It coagulates after death, and then pre-
sents the white opaque curdy appear-
ance with which all anatomists are
familiar. Each one of these fibres,
according to the elaborate investigation of Ehrenberg and Miiller,
however frequently they may cross each other, or appear to
unite, whether they are rolled up in separate bundles as in the
nerves or penetrate in masses through the ganglia or through
the substance of the brain, never unite or do more than come in
close apposition with one another ; every where being kept sep-
arate by their neurilematic sheaths, which insulates them as

* Fig. 215. — Minute structure of nerve (from Wilson). 1. The mode of
termination of nerve-fibres in loops ; three of these loops are simple, the fourth
is convoluted. The latter arrangement is found in situations where an exalted
degree of sensation exists. 2. A nerve- fibre from the brain, where the neuri-
lematous covering is very thin, showing the varicose appearance produced by
traction or pressure. 3, A nerve-fibre enlarged to show its structure — viz. a
tubular enveloped, and a contained substance, neurine. 4. A nerve cell or
granular globule of cineritious neurine, showing its composition to consist of a
granular looking capsule, and granular contents. 5. Its nucleus containing a
nucleolus. 6. A nerve cell from which several caudate (or tooth-like) processes
are given off. It contains like the preceding, a nucleated nucleolus. 7. The
third constituent of the medullar}' masses, namely, granules or rather minute
cells. These are dispersed among the cerebral fibres in great numbers j they
present every variety of size and are many of them nucleated.

NEURILEMA OF THE WHITE FIBRES.

547

completely from one another as the Fig. 216.*

windings of a silk thread, insulate the
coils of wires, which serve as the con-
ductors of a galvanic battery. When
the bundles of white fibres constituting
two or more nerves come together, and
appear to anastomose directly or form a plexus, there is there-
fore only a separation of the primitive filaments and a recombi-
nation of them in a different order as they leave the plexus, so
as to render more intimate the connexion existing between differ-
ent organs of the body. In this manner the nervous substance
of each fibril, is maintained separate in its course, so as to have
no functional communication, Fig. 217.f

except with the part from which
it arises, and that to which it is
distributed ; and however flexu-
ous or involved its direction may
be, or with whatever different
orders of nerves it may be inci-
dentally bound up, its functions
are, nevertheless, as directly and
singly exercised, as though there
existed but one order of fibres
in the body. The extremities
of the nervous fibres, are not
abrupt like the cut ends of a
cord. They appear to have their origin in the gray matter in
the form of a loop, and to terminate at their distant extremities
in loops, which is highly convoluted in the cutaneous papilli
and other sensitive parts, as shown in fig. 215. The neurile-
matic covering investing the primitive fibres, is very delicate,
almost gelatinous or structureless in the brain, so as to render

* Fig. 216, is a microscopical view, after Raspail, of a transverse sectiou of
a branch of a ganglionic nerve, which appears as a single cord. The cut ends
of the numerous filaments are here seen, included in the general sheath or
neuriiema of the cord.

■)■ Fig. 217, a similar transverse section of a median nerve, which exhibits
several cords, ever}' cord or fasciculus having its own membrane, and all in-
cluded in an envelop or neuriiema common to the whole. The cut ends of the
fibrils forming each fasciculus are seen. The single dark spot represents a
blood-vessel.

548 CHEMICAL ANALYSIS OF THE BRAIN.

the tracing of the fibres through that organ, a matter of extreme
difficulty.

— But the existence of the neurilema there is nevertheless evi-
dent, and especially, as I have several times had occasion to
observe in cases of atrophy of parts of the brain, where the
nervous substance had disappeared, and the neurilema been left,
forming a shrunken mould of the part.

— In the sympathetic nervous system, there is, according to
Remak, a mixture of white and gray fibres, constituting the
trunks of the nerves. The primitive gray fibres, originate from
the sympathetic ganglia, are about one half the diameter of the
corresponding white fibres, and have their surface here and there
beset with minute granules of gray matter. The white fibres
which are seen in the sympathetic nerves intermixed with the
gray, especially in the neck, the loins, and the splanchnic nerves,
are believed to be additional sensitive, and perhaps excito-motor
nerves extending into them from the cerebro-spinal system.
— Some of the cerebro-spinal nerves, as the trigeminus and
glosso-pharyngeal, contain some gray fibres of a similar sort,
which are derived from the sympathetic, and intermixed with
those coming from the brain.

— Mr. Johns* is the only chemist who, in his analysis of the
brain, has hitherto separately examined the gray and white mat-
ter. He has stated that the white matter contains more fat than
the gray, and that its albumen is more firm. The following
comparative analysis was made of the brain of one of the insane
patients who died at the Salpetriere.

Entire Brain, (^Density 1048.)

Water, . . . . _ 77.0

Albumen, - - - - - - 9.6

White fatty matter, - - - - 7.2

Red fatty matter, - - - - 3.1

Osmazome, lactic acid, salts, - - - 2.0

Earthy phosphate, - - - - 1.1

* Journal de Chimie Med. 1835 ; Solly on the brain, p. 8. London, 1836.

DIVISIONS OF THE NERVOUS SUBSTANCE. 549

( Comp.

Analysis.)

White Subst.

Gray Subst.

Water, -

- 73.0

-

-

85.0

Albumen,

9.9

-

- 7.5

White fatty matter

, 13.9

-

-

1.0

Red fatty matter,

- 0.9

-

- 3.7

Osmazome, etc..

1.0

-

-

1.4

Earthy phosphate,

0.3

-

- 1.2

Functional Divisions of the Nervous Substance.

— The student who wishes to form for himself a comprehen-
sive and philosophical knowledge of the structure and func-
tions of nervous matter, will do well to examine it in its
simplest state of development as it is found in the radiated or
star-shaped animals, in which unequivocal voluntary locomo-
tive power exists, and where it is found dissected and simpli-
fied as it were by the hand of nature. In these animals we
find a ring of nervous ganglia, connected by intermediate cords
or commissures which unite them together, surrounding the
mouth and oesophagus ; and from the little nodules or ganglia
which are placed opposite the rays or limbs of the animal, part
nervous cords, which are distributed to the muscles, and are
unquestionably the instruments of locomotion. Proceeding
in his investigations up through the articulated, molluscous,
and vertebrated animals to man, he will find the nervous sys-
tem expanded in form, and complicated in arrangement, so as
to harmonize exactly with the development of the different
classes of animals, and the elevation of their vital functions.
Life, which appeared at the zero point of the scale, to be
manifested chiefly by motions excited by the contact of bodies,
(mere excito-motory phenomena,) becomes complicated as we
ascend, with the presence of other functions, larger ganglia
being placed at the region of the head, which give the instinc-
tive impulses to the animal. As we proceed upwards towards
man, we find a cerebral ganglion, assuming more and more
the appearance of a brain, and endowed with instinctive
faculties, which approach slightly in character to the moral
and intellectual. Finally, in man himself we find this part

550 DIVISIONS OF THE NERVOUS SYSTEM.

expanded forward and upward so as to constitute a preponde-
rating mass of nervous substance, called encephalon or brain,
which retains all the instinctive properties found in similar
organs of the animals below him, and is endowed in addition
with the high and governing qualities of the mind ; some of
the organs, as those in the interior of his body, still living and
acting by a system of excito-motory or organic phenomena,
like those of the radiata, and for which we find arranged a
separate system of ganglia and nerves.

— In tracing up the anatomy of the nervous system in this man-
ner, it will be found to consist entirely of the cineritious and
medullary neurine, variously disposed throughout the body, so
that the whole nervous structure, can be classed according to its
functions into three parts. 1st. Ganglia composed principally
of cineritious neurine, and which are believed to be the only
sources of power in the nervous system. 2d. Commissures or
bands which connect and associate the different ganglia with
each other, composed sometiiDes of the cineritious, but most
generally of the medullary neurine. And 3dly. Nerves or
cords, formed almost exclusively of the medullary neurine,
which establish communications between the ganglia, and all the
different portions of the body. The nerves are but the passive
agents of the ganglia, and have but a single and common func-
tion, and the commissures, so far as their offices have yet been
made out, have no more ; but the ganglia, differing among them-
selves greatly in size and form, seem on either half of the body
to be each one endowed with its peculiar function. Solly,* a
late writer on this subject, has fully carried out this idea in his
treatise on the brain.

— Adopting at the outset, this rational and philosophical view
of the nervous system, the student will have a physiological
guide before him, which will, more satisfactorily than any
other, lead him through this interesting and important portion
of anatomy, that is yet far from being perfectly understood,
and is obscured by a multitude of terms, applied often coarsely
to different parts of the same physiological organ, from their
fancied resemblance to other objects, or from mistaken views

* Op. citat.

GENERAL ANATOMY OF THE NERVOUS SYSTEM. 551

in regard to their functions. The perpetuation of these sense-
less terms, devised, many of them, at an early period of the
science, and the conflicting accounts given of the structure and
functions of the different parts of the brain, have rendered
the nervous system a perplexing study, from which even a zeal-
ous student is apt to rise despairingly, his memory loaded with
names, and his mind charged with very indefinite notions of the
structure and functions of nervous matter. Neurology within
the last half century, has made such rapid advances, that anato-
mists have become emboldened, to study the parts of the nervous
system in their natural order ; tracing the fibres of the brain
from below upwards, without reference to the artificial system so
long practised, of dividing it in horizontal slices, which can no
more teach the structure of its different parts, than would a series
of transverse sections of the thigh, teach us the origin, course,
and uses of the different muscles of that region. Following out
these views of late investigators of the nervous system, we shall
see many difficulties to disappear from the tangled subject, and
the whole present itself in a light much more lucid and tangible
to the mind.

Of the Ganglia.

— The term ganglion, which was originally applied to a
knot or rounded mass of isolated cineritious neurine developed
in the course of the white fibres of a nerve, may well be
applied, since the term has come into such common use, to any
isolated mass of cineritious substance, whatever its form ;
whether spread out in a thin layer, folded upon itself as in the
outer part of the cerebrum and cerebellum, or forming a long
cylindrical mass surrounded by the white matter, as in the
spinal marrow ; since the generally rounded ganglia of the
nerves, present themselves under all varieties of forms, and
thus prove that shape exercises no specific influence in regard
to their function.

— Hence, the outer layers of the hemispheres of the brain, are

now spoken of as the hemispherical ganglia,* in which the

intellectual and moral faculties have their seat ; the cineritious

* Solly oper. citat.

552 THE NERVES.

nucleus of the spinal marrow, as a series of spinal ganglia,
(found in the lower animals to consist of separate
knots,) whose office in particular it is, to preside over the
sensations and voluntary motions of the limbs and body ; the
ganglia of the sympathetic nerve, having mainly under their
control the peculiar sensations and involuntary motions of the
visceral organs.

Of the Medullary Neurine forming the Commissures.

— White bands of medullary neurine are found in many por-
tions of the cerebro-spinal system, passing from side to side
between symmetrical ganglia, (arising from one, so far as we
can carry our investigation, and terminating in the other,) which
are called commissures, and whose office it appears to be, to
attach together these different organs so as to give to them a
certain sort of unity in their operations.

— We have one instance of the many commissures that exist,
in the corpus callosum, which is extended across between the
two hemispheres of the cerebrum, at the only place where they
can come in contact, immediately below the falx major ; and
another in the white fasciculi that pass across from the cere-
bellum over the pons varolii, (see fig. 224, page 577,) and meet
with those of the opposite side on the middle line of the pons.
These constitute the great commissures or bonds of union of
the two sides of the cerebrum and cerebellum.
— In the ganglia of the syn) pathetic, parts of the fibres of the
evident white cords connecting the ganglia together, are
believed, by Solly, to belong to the system of commissures.

Of the Nerves.

— The means by which the ganglia are placed in connexion
with the organs of sense, the skin, muscles, and other portions
of the body, are the thousands of white medullary filaments,
which, shortly after their origin from the central parts of the
nervous system, pass out among the other tissues of the body,
where they are rolled up into cylindrical cords and receive the
name of nerves. These, for the purposes of greater clearness
in description, are represented as dependencies of the central

THE CINERITIOUS AND MEDULLARY NEURTNE. 553

ganglia and running from them to the different parts of the body.
But they are, in fact, merely agents of communication, between
the various ganglia of the nervous system, and the different
organs of sense and motion ; some fibres carrying impressions
from without inwards to the ganglia ; others in the opposite
direction, transporting the motive or other influences which these
impressions have excited in the ganglia, (especially those of the
cerebrum,) outwards to the muscles.

— It has been already observed, that the medullary substance,
consists, when closely analyzed, of minute elementary fila-
ments, each one surrounded by a separate neurilema, or cylin-
drical sheath, which isolates it in its passage through the dif-
ferent parts from its origin to its termination, and at the same
time serves to support it in connexion with the coats of sur-
rounding filaments, a number of which go to constitute a
nervous cord. In the brain and spinal marrow this same fila-
mentous arrangement exists, though more difficult of observation
there, in consequence of the nervous filaments, as they are
extended upwards into the brain, being no longer rolled up in
cords, but placed in juxtaposition with each other so as to form a
solid mass, each filament at the same time being compressed
into a smaller space, so as to be diminished in its diameter.
— The diameter of the primitive filaments found in the nerves
is, as has been already stated, about ,JS.th part of a line, or
nearly the 3500th part of an inch. But as they pass up into
the brain through the spinal marrow, or through the encephalic
nerves, they become so much lessoned in their diameter as not
to measure more in the medullary substance of the brain than
the TCoo^h part of an inch, or more than T^goo^h where they
terminate in the cortical portion. From this cause and the
great delicacy of the investing neurilema there is much diffi-
culty in tracing their individual course within the cranium, but
the fact that a large portion of the white fibres of the brain are
continuous with those of the nerves, will no longer admit of
being called in question. We say a part of the white fibres
of the brain, for there is some reason to believe, that accord-
ing to the doctrines of Gall, some white fibres, arise de novo,
in the gangliform masses of cineritious matter placed at the
VOL. II. 47

554 COURSE OF THE NERVOUS FIBRES.

base of the brain, and go to increase its bulk. On the other
hand, recent researches have shown that a part only of the
nerves, are continuous with the brain ; some terminating and some
originating in the gangha as organic filaments, and others termi-
nating and originating in the cineritious substance of the spinal
marrow and the base of the brain, to which the term excito^
motory has been applied. The anatomical grounds for the adop-
tion of this term require to be investigated. That it renders the
'study of the functions of the nervous system, more clear and
comprehensible, is something in proof of its anatomical correct-
ness. The researches of Flourens* have shown, conclusively,
that the seat of ordinary sensation and voluntary motion, is ex-
clusively in the brain, and that yet there are many parts of the
body gifted with peculiar instinctive sensations and involuntary
movements, which are capable of exercising their offices to a
greater or less extent, even when separated from the brain.
Such are the parts which receive their supply from the ganglia
of the sympathetic, and some too which obtain it through nerves
sent off from the spinal marrow and medulla oblongata.
The dissections and experiments of Sir C. Bell, before
whose time the spinal marrow was considered a sort of
tail-like appendage to the brain, as well as those of Magendie,
have established as unquestioned facts, that the anterior and
posterior roots of the spinal nerves, and the anterior and pos-
terior colunms of the spinal marrow from which these roots
come out, are destined, — the former or anterior, for motion,
and the latter or posterior, for sensation. Many of the other
opinions of Sir C. Bell, in relation to the nervous system,
have not stood the test of closer examination, and according
to Mr. Grainger, his own views in regard to them were altered.
Thus, beside the anterior and posterior columns of each half
of the spinal marrow he admitted a middle or lateral portion,
between them, which other anatomists have not been able to
discover. He supposed all the white fibres of the cord conti-
nuous with those of brain on the one hand, and with those

* Recherches Experimentales, sur le Propr. et les Foiict du Syst. Nerveux.
2d edit. 1842.

ORIGIN OF THE SPINAL NERVES. 555

of the nerves on the other; the most superficial of the fibres
of the cord passing away, as the cervical nerves, and that thus
the whole were given off in succession, till the most internal
left it below, as the sacral and coccygeal ; thus making the
spinal marrow merely a large nervous cord, in which the cine-
ritious matter placed in its interior, appears no more to be
needed than in any other nervous trunk. At the upper part,
however, of the spinal marrow, where his imaginary lateral
column is placed, he believed the nerves destined to respira-
tion arose, and that these were capable of exercising their
functions occasionally, as in sleep and apoplexy, through the
influence of this column alone, without, and even in opposition
to the agency of the will.

— Sir C. Bell however by his experiments, established an inter-
esting fact, that the function of respiration, even in man, is
partly an instinctive act, and thus opened a new and impor-
tant path of investigation. Anatomists following in his train
of observation, have shown the cineritious nucleus of the
spinal marrow, to be the source and origin of many of the
fibres of the spinal and cerebral nerves, as he supposed the
lateral column of the medulla oblongata to be to the respira-
tory. Meckel and Cruvielhier assert that this appears to them
to be the case ; Ollivier and Gall, have asserted it more boldly.
Mayo and Marshall Hall,* seem to have proved it by their
experiments, in which they separated the cord from the brain at
various heights, and observed that nerves which came off from
below the place of separation, running to the eye, nose, anus,
etc., were still found, on mechanical irritation, to possess a sort
of instinctive sensation, and to be capable of producing com-
bined involuntary muscular movements to a certain extent.
More recently Mr. Graingerf of London, by adopting an
improved method of investigating the origin of the nerves,
has succeeded in tracing a part of the fibres of the anterior
and posterior roots of all the spinal nerves, into the cineritious

* Vide Mayo's Physiology, and M. Hall on the Nervous System.

f On the Structure and Functions of the Spinal Cord. London, 1838.

556

GENERAL ANATOMY OF THE NERVOUS SYSTEM.

matter of the spinal marrow, where they appear to end ;
another portion of the fibres of the same nerves, turning
upwards, and constituting a part of the spinal cord in its
course to the brain. This arrangement of the nerves in the
medulla, see fig. 221, Mr. Grainger observes, he demonstrated
Fig. 218. to the entire satisfaction of

Professors Arnold, Bur-
dach, and Sir C. Bell.
The same thing has also
been nearly conclusively
shown to exist in regard
to the encephalic nerves,
the principal difference
between which and the
^^ spinal nerves is the origin
of the former from a differ-
ent portion of cineritious
matter, and their not so
usually having their fibres
of sensation, and their
fibres of motion rolled up
into a common fasciculus,
as is the case with the
spinal nerves, but running
out to their destination
^■'' '''j mainly as distinct nerves,

either of motion or sensation. The fibres of the anterior and
posterior roots of the spinal nerves, that terminate in the spinal
marrow, are called by Hall and Grainger, the true spinal,
excito-motory , or incident and rejlcx spinal nerves, and are con-
sidered to derive their origin and power from the cineritious
matter of the spine in which they arise, and to have functions
as much involuntary and organic, as any of those which belong
to the sympathetic nervous system. Those which pass upwards
into the brain are called the cerebral sensiferous and cerebral
motorial nerves.
— Fig. 218, is a plan of the spinal cord from Grainger, intended

GENERAL ANATOMY OF THE NERVOUS SYSTEM. 557

to show the arrangement of the gray and fibrous substances
in profile, the course of the true spinal or excito-motory
nerves, and that of the true cerebral sensiferous and motorial.
A. Posterior surface of the cord. B. Anterior surface. C. The
cineritious or grey matter in the centre of the spinal marrow.
D, E. The true spinal or reflex nerves ; the incident or spinal
sensiferous nerve may be supposed to approach the spine at
D, the true motor spinal nerve leaving at E, which is capable
of producing contraction in the part to which its fibres are dis-
tributed when excited by the cineritious matter that receives
the stimulus brought by the incident spinal nerves at D. The
roots of the fibres of the two sides probably form some con-
nection in the cineritious matter. F. The cerebral sensiferous
fibres going to the brain. G. The motor cerebral fibres dis-
tributed to the muscles of volition. The respiratory nerves
of Sir C. Bell, will no longer then stand apart as a separate
system, but comes under the same category with the excito-
motory, to which the great sympathetic, as has been already
shown, in a measure belongs.

47*

558 THE MEDULLA SPINALIS.

CHAPTER XVII.

OF THE SPECIAL ANATOMY OF THE SPINAL MARROW AND
BRAIN, AS DESCRIBED FROM BELOW UPWARDS.

— Having investigated the general anatomy of the nervous
system, the student may enter with advantage upon the study
of its particular parts ; and for the convenience of demonstra-
tion, it will be best to retain the artificial divisions, commonly
made, viz. : 1st. The brain and spinal marrow, which forms
the cerebro-spinal axis of Meckel, and the forty-two pairs of
encephalic and spinal nerves which they give off; and 2d. The
ganglia aad nerves of the great sympathetic or ganglionic
system.

Of the Medulla Spinalis of Man.

— The medulla spinalis, is a cylindrical cord, slightly flattened
in its antero-posterior diameter. In the adult it is on an
average about sixteen inches in length, and extends from the
first or second lumbar vertebra,* to the basilar foramen of the
occipital bone, where it is directly continuous with the medulla
oblongata, and through the latter with the cerebrum and cere-
bellum.

— The transverse or larger diameter of the cord, is, at the mid-
dle of the back, five lines ; but at the lower part of the neck,
and the lower part of the back, where the great plexuses of
nerves are given off to the upper and lower extremities, it is a
line or two more. It is surrounded by three membranes, like
the brain ; viz. the dura mater, tunica arachnoidea, and the pia
mater, the latter of which closely embraces the medulla. It is
enclosed its whole length in the spinal canal, the diameter of
which is much greater than that of the medulla ; it doos not

* Keuffel has seen it commencing opposite the eleventh dorsal vertebra in
one case, and the third lumbar in another.

THE MEDULLA SPINALIS. 559

occupy exactly the centre of the canal, hut, according to 0111-
vier, rests against its anterior wall in the vertical position, and
inclines towards the posterior, especially at its lower part, when
the individual rests upon his back. The consistence of the
medulla is much greater when healthy and observed in the recent
state, than is generally supposed ; it surpasses that of the cere-
brum and cerebellum, though it is in general less than that of
the pons varolii.

— The weight of the medulla spinalis, separated from its mem-
branes and nerves, is in the adult in proportion to the entire
mass of the brain, according to Meckel, as one to forty. Man,
however, is, of all animals, the one in which the medulla spi-
nalis is the least in comparison with the brain : a fact, well
exemplified by comparative anatomy, in which it will be found
that the more we recede from man in the scale, the greater is
the proportion of the medulla to the encephalon. The spinal
medulla presents in its course two remarkable enlargements ;
one, superior, named cervical or brachial, which extends from
the third cervical vertebra to the second dorsal ; and the second,
between the fourth dorsal vertebra and the second lumbar,
which is called the lumbar or crural. Below the crural plexus
the medulla is fusiform, and terminates most generally in a
point, but sometimes in a bulb, and occasionally in a bifurca-
tion.

— The spinal cord, is divided into two symmetrical portions —
that is, — one for each side of the body by two median fissures ;
one called the anterior median fissure, forms a groove on its front
surface of a depth equal to one-third of the diameter of the cord,
the other gi'oove on its back part, called the posterior median
fissure, is deep at the upper part of the medulla, but becomes
quite superficial below. The anterior median fissure is more
distinct and wider than the posterior. Both fissures run the
whole length of the cord, and are to be found at all periods of
life. In fig. 219, are seen transverse cuts of the medulla, show-
ing its division by the anterior and posterior median fissures, into
the two symmetrical halves.

560

CINERITIOUS NEURINE OF THE SPINAL CORD.

Fig. 219.* — The transverse sections

b c of the cord show that it is

solid throughout, though it
has erroneously been as-
serted by some anatomists
to possess a canal in its centre. Its outer portion is composed
exclusively of the white or fibrous neurine, and its interior con-
tains a considerable portion of the cineritious or pulpy neurine,
called sometimes the nucleus of the spinal marrow.
— The quantity of cineritious or gray matter included, varies
very much at different heights of the cord, as seen in the follow-
ing cuts.

d

Fig. 220.t

— Every where in the spi-
nal cord the medullary en-
velops the cineritious neu-
rine, the reverse of what
takes place in the lobes of
the cerebrum and cerebel-

* Fig. 2 L9 represents transverse sections of the spinal cord at different heights,
the large proportion of the central cineritious neurine compared with the me-
dullary, and the variation in shape and size of the former, at different portions
of the spine ; the size of the medulla being always greater at the points, where
the largest number of roots to the spinal nerves are given off. The anterior
surface of the cord, which is seen above, shows the anterior median fissure ;
opposite to it below, is seen the posterior.

The shape of each symmetrical portion of the cineritious nucleus, is more or
less semilunar ; the anterior extremity or horn being blunt or round, and pre-
senting towards the point where the anterior roots of the nerves are given off.
The posterior extremity is acuminated, and terminates in the lateral fissure from
which arise the posterior roots of the nerves, and which divides each half of the
spinal marrow, into the posterior, and autero-lateral column, a, Is a section
opposite the eleventh dorsal vertebra, b, a section opposite the fifth dorsal, and
c, one opposite the fourth cervical.

t Fig. 220, rf, is a representaiionofa^transverse section of the spinal marrow,
opposite the third cervical vertebra. The bulk of the cineritious neurine in this,
contrasted with that of a section immediately below it, opposite the fourth cer-
vical, (see fig. 219,) from which the brachial plexus in part arises, is very small,
e. Is a transverse section of the medulla oblongata, a little above the middle of
the corpora olivaria showing the arrangement of its cineritious neurine, in three
portions, corresponding with the divisions of the medulla oblongata, into three
bodies. 1. Cineritious nucleus belonging to the corpus pyraraidale. 2. Cine-
ritious nucleus belonging to the corpus olivare of the same side. The dark line
below fig. 2, belongs to the corpus pyramidale. Both of the figures in this cut
are taken from Solly.

FISSURES OF THE SPINAL MARROW. 561

lum. The contrast of color between the two substances is the more
marked, the younger the subject upon which the examination
is made. In old age the contrast ceases to be distinct ; the
central nucleus of the medulla presents but a grayish tint,
yellowish at its border where it unites with the medullary
matter, which has likewise become of a yellowish color.
— The shape of the cineritious nucleus of the medulla spinalis,
is in most parts like that of two )— ( united thus back to back ;
in others it presents the appearance of four bands of cineritious
matter, one anterior and one posterior to each half of the
medulla.

— These four bands, or the two c' are very generally united
together in the centre of the medulla, though Keuffel, has
found those of each side entirely separate. The anterior horns
or bands, do not quite reach the surface of the cord, but are
exactly opposite the connexion of the anterior roots of the
nerves with the spine. The posterior extend completely
through its substance, at the point where the posterior roots are
connected with the cord. The bulk of the cineritious matter
is always larger, where the largest amount of nerves are
connected with the medulla, as in the brachial and lumbo-
sacral plexus. It is also relatively to the white neurine,
larger in man than in any other animal. The anterior horns
of the cineritious matter, are not so long, but are thicker than
the posterior.

— The anterior and posterior median fissures do not quite
extend into the cineritious nucleus ; the bottom of the fissures
is closed by a layer of white matter, which is evidently trans-
verse in the anterior, and, as I have repeatedly seen, is
formed of a sort of medullary pellicle arising from the anterior
part of each half of the cord, so as to form a union or commis-
sure between the two halves. The posterior fissure is closed in
a similar way, notwithstanding the assertion of Gall and Spur-
zheim that the fibres of the posterior commissure were longitudi-
nal in their directions. The longitudinal appearance of the fibres
observed by these anatomists is made by the tearing up of the
vessels in removing the pia mater. Each of these transverse

562 ANTERIOR AND POSTERIOR ROOTS OF THE SPINAL NERVE.

bands is pierced with a great number of openings, through which
the vessels run from the pia mater into the cineritious nucleus.
— The medulla spinalis is divided, as we have seen, into two
symmetrical halves, by the anterior and posterior median
fissures. Each half of the cord has connected with it upon
the side, thirty-one pair of nerves, called the spinal nerves;
each nerve communicates with the medulla, (or, as is more
commonly said, arises from it,) by two roots, called the anterior
and posterior roots of the spinal nerves. Viewing the spinal
cord and nerves in connexion with their functions, it would be
more correct to say, that the anterior roots only arise from the
cord and run outward, and that the posterior terminate in the
cord ; for it has been satisfactorily proved, as has been before ob-
served, that the anterior roots are the nerves of motion, that is,
conductors of the will to the voluntary muscles, and that the
posterior are the nerves of sensation, conveying the impressions
from without, through the medium of the spinal marrow to
the brain, which is the seat of consciousness.
— The fasciculi of the posterior roots are much larger than
those of the anterior. They pass through a small oblong
ganglion, just before their connexion with the cord, while
upon the anterior roots there is no ganglion. Upon the outer
side of the ganglion the filaments of both roots are inextricably
interwoven. The fasciculi of both roots of the different spinal
nerves, form flattened pyramids, at the base of which they
communicate with the medulla spinalis, and the pyramids
formed by each root nearly touch each other at their upper
and lower margin, throughout the whole length of the spine.
— The anterior arise from a superficial fissure on the external
surface of the medulla, which extends throughout its whole
length, and is exactly opposite the termination of ihe anterior
horn of cineritious matter. This is called the anterior lateral
fissure. Between the bottom of this fissure and the anterior
horn of cineritious matter, there is nothing but a very thin
lamen of medullary matter.
— The connexion of the posterior roots, is by a fissure much

WHITE AND GRA.Y SUBSTANCE OF THE CORD. 563

deeper than the former, which is called the posterior lateral
fissure. The bottom of this fissure is formed by the projection
of the posterior horn of the cineritious crescent.
— From the greater depth of this fissure, and from the results
of experiments by vivisection upon the spine, it has been con-
sidered as subdividing each half of the spinal cord into two
columns. The anterior, which comprises all between this
posterior lateral, and the anterior median fissure, is called the
motorial column, and that which is behind the posterior lateral,
the sensorial column. The anterior forms a large part of each
half of the cord, as seen in fig. 221, and is frequently spoken
of as the antero-lateral column. At the lower part of the dor-
sal, and in the lumbar region, it is one-fourth part larger than
the posterior ; in the cervical region it is double the size, and in
the medulla oblongata, yet to be spoken of, it forms a still larger'
portion.

— The white fibres of the cord are very simply arranged,
lying parallel to each other ; in consequence of which they
are easily stripped off, leaving the surface below smooth and
regular, so that, as Sir C. Bell observes, " it appears that the
superficial layers, furnish the roots of the higher nerves, and that
the lower layers, go off to the roots of the nerves, as they suc-
cessively arise."

— The cineritious matter, on making a longitudinal cut of the
cord, is seen passing up, as a column of granular matter, and
terminating in the medulla oblongata, at the lower part of the
fourth ventricle of the brain, and between the corpora restifor-
mia, where it forms a grey mass called by Wenzel, tuberculum
cinereum. The gray matter of the cord does not, in the adult
or in the embryo, present the appearance of separate, gan-
glionic masses, of which Gall believed it to consist. It is,
however, believed by Miiller, Mayo, Hall, Grainger, Solly,
and others, to be entirely analogous in its offices to the nodules
of the articulata, though it is not, as in animals of that class,
interrupted in the intervals of the attachment of the nerves.
This opinion is in accordance with the laws of development
in the inferior animals. In . the pupa of some insects, the

564 CONNEXION OF THE NERVES WITH THE CORD.

ganglia exist in an isolated state, but are made to approach each
other in the more perfect development of the animal and become
fixed into a sort of spinal marrow, without any impairment of
their functions.

— The function of the gray matter of the spinal cord, may
nevertheless be precisely the same in man, as though it was
divided into separate masses. It has before been shown that
no communication takes place laterally between the fibres of
the medullary matter, however closely they may run in con-
junction, their neurilematic covering isolating them from each
other. The same may take place in regard to the globules of
cineritious matter, each of which is surrounded and separated
from the rest by a cellular envelop, and appears, as shown by
the microscopical observations of Remak and Miiller, to act an
independent part in giving origin to an individual medullary
fibre.

Connexion of the Nerves with the Cord.

— In this granular mass of cineritious substance in man and the
inferior animals, there are no fibres of any description to be
seen in a longitudinal section. But in a transverse cut, as has
been pointed out by Bellingeri, Mayo, and Grainger, a spotted
appearance is presented, in consequence of the intermixture of
the white fibres with the gray-substance. " The source and
connexion of the white fibres," says Grainger,* " thus placed
within the gray, are not known ; but it is certain that they must
in part, if not entirely consist of certain fibres, which pass into
the gray substance from the spinal nerves." He believes
the peculiar crescentic shape of the gray matter depends upon
the anatomical connexion of the nerves ; some of the fibres of
both the anterior and posterior roots, passing into the gray
substance, the junction of which is favored by one horn
being turned forward and the other backward. After repeated
examination, in man and the superior animals, Mr. Grainger,
appears to have fully verified the opinion, entertained by most

* Ob. citat.

CONNEXION OF THE NERVES WITH THE CORD.

565

Fig. 221.

anatomists of the present day, that the fasciculi of the spinal
nerves, are more or less connected at their origin with the
cineritious neurine of the spinal cord. Fig's 221 and 222,
represent the connexion of the spinal nerves with medulla of
the dog, and such as he proved it in man, in conjunction
with his colleague Mr. Cooper, and Professor BischofF of
Heidelburg.

— Fig. 221 is the anterior surface of
the spinal cord, where is seen the
true roots of the anterior or motor
nerves. A, The anterior median
fissure, B, the anterior lateral. C C,
The anterior roots of the nerves ;
c' those running up the cord to the
brain, and forming part of the
white matter encircling the gray
neurine, and called the cerebral or
true volition fibres, and c", spinal or reflex, seen dipping in the
gray matter of the cord.

— Fig. 222, is a view of the posterior
surface of the same cord. D, the
posterior median fissure, E, poste-
rior lateral ; F F, posterior root of
the nerves, dividing into f, cerebral
or true sensiferous fibres, which
run up on the posterior part of the
cord to the brain ; /', true spinal or
incident nerves according to Hall
-f and Grainger, seen entering the
gray substance of the cord. These
roots are invested with the gray
matter like the fibres from the crus cerebri in the corpus
striatum. In fig. 218, is seen a plan of the arrangement of the
gray and fibrous structure seen in profile.

— All the parts within the cavity of the cranium to which the
medulla spinalis runs, are classed under the general name of
encephalon or brain, which consists of a variety of parts vary-
voL. II. 48

Fig. 222.

566 LIGAMENTUM DENTICULATUM.

ing much among themselves in regard to structure and function^
and which have been concisely but very clearly described in
their general outlines, at page 371.

— It has there been shown that the brain and spinal marrow,
are similarly inclosed within three continuous protecting
membranes ; the dura mater, tunica arachnoidea and pia
mater, which terminate in closed sacs over the top of the brain,
and in an acute extremity at the lower portion of the spinal
marrow.

— The dura mater and tunica arachnoidea are analogous in
structure, throughout the whole of their extent ; but the pia
mater is considerably modified in the spinal canal.
— The line of division established between the medulla spi-
nalis, and the medulla oblongata, is within the ring formed by
the atlas vertebra; this division is altogether arbitrary, and
Cruvielhier has shown, by a number of experiments, that in flex-
ion of the head, the spinal marrow is drawn up above that level.
In the whole extent of the movable chain of bones forming the
spinal column, flexion takes place in various directions, and
it is to admit of this movement without risk of compressing
the medulla, that the cavity of the bony canal, and that of the
spinal dura mater and arachnoid membrane, are so much
larger in diameter than the medulla itself. The immediate
protecting organ of the medulla in flexion and extension of
the spine is the pia mater, which in the spine tightly embraces
the medulla, and is there so changed, that instead of the deli-
cate cellular and vascular appearance, which it presents before
it descends from the brain, it has become a firm, resisting,
fibrous membrane. A close inspection of this membrane as
it exists in the spine of the elephant and bullock, as well as
in man, has convinced me of a fact, which has generally
escaped the observation of anatomists ; viz. that it forms like-
wise, by a duplicature of itself upon the sides of the medulla,
the ligamentum denticulatum, described in page 395, which
ligament is fastened at its outer margin by processes of insertion
in the dura mater.
" — FipT. 223, is a drawing I have made from the cervical portion

I.IGAMENTUM DENTICULATUM FORMED BY THE PIA MATER. 567

of the spinal marrow of the elephant, a, Is the dura mater;
the arachnoid membrane being removed, c, The medulla
spinalis, d, The pia mater, closely embracing the medulla,
and dipping in, in the form of a fold, to the bottom of the ante-
rior median fissure e, and the posterior y*. g, Doubling of the
pia mater, forming the ligamentum denticulatum. i, i, The
tooth-like processes of the ligament, by which it is inserted into
the inner face of the dura mater ; the ganglion k, formed on
the posterior root of the nerve, as well as the anterior root, is
closely embraced by a process from the dura mater b, forming
its neurilema. In this manner the medulla is always effectually
maintained in the middle of the lateral diameter of the spinal
canal.

Fig. 223.

Of the Medulla Oblongata.

— ^The medulla oblongata, (see fig. 224, page 577,) is obviously
a prolongation of the spinal marrow as its name imports, and is
the medium of communication, between all the parts of the
body which receive nerves from the spinal cord and all the por-
tions of the cerebrum and cerebellum above. Hence it has
been called the central point of the nervous system, and as it
gives origin to nerves, (pneumogastric, etc.,) directly connected
with the performance of functions the most immediately neces-
sary to life, it is deserving on the part of the anatomist of the
most patient study. It occupies the groove in the basilar pro-
cess of the occipital bone, and is covered on its posterior surface
by the cerebellum.
— It is about fourteen lines long, nine lines wide at its largest

568 MEDULLA OBLONGATA.

part, and about six lines thick. Below, it is continuous insensi-
bly with the spinal marrow ; above it terminates in, or rather
passes through the pons varolii, (fig. 224,) by means of which it
is continuous with the cerebrum ; and on its back part through
the corpora restiformia, it is continuous with the cerebellum.
— The anterior median fissure of the medulla spinalis is con-
tinued up over the medulla oblongata ; it may be traced as a
superficial groove over the pons varolii and is seen terminating
in the fissure between the crura cerebri.

— The posterior median fissure extends up on the back part of
the medulla oblongata, to a cavity called the fourth ventricle,
where the back part of the medulla oblongata seems to open
and branch off towards the cerebellum. These two fissures
divide the medulla oblongata into two lateral halves, like the
divisions of the spinal marrow. On each of these divisions we
observe three elevations. One called the corpus pyramid ale (b.
fig. 224), from its triangular shape, which is broader above than
below, and bounds the anterior median fissure ; one called the
corpus restiforme, from its rounded shape, m, that forms the side
of the posterior median fissure as well as part of that of the
fourth ventricle, where it diverges from its fellow to so to the
cerebellum. Between the two, upon each side, is seen an ob-
long elevation, called the corpus olivare, c c, which is situated
a little obliquely from without inwards, and from above down-
wards. These three bodies do not, however, occupy the whole
surface. of the medulla oblongata; between the corpus olivare
and the corpus restiforme, an unelevated band of fibres is seen
passing up called the corpus innominatum by Cruveilhier,* and
which was first particularly pointed out by Sir C. Bell, as the
lateral column.f

— In the account of the spinal marrow, it has been observed
(page 556,) that the anterior and posterior roots of the spinal
nerves, have been proved unquestionably to be endowed with

* Sir C. Bell's division of each half into three columns, is no longer con-
sidered tenable.

t These parts have had the name of posterior pyramids applied to them by
Eolando and Ollivier. The same term has been applied by others to the corpus
restiforme.

MEDULLA OBLONGATA. 569

different functions ; the anterior witii that of motion, the poste-
rior that of sensation, and that the same division exists in regard
to each half of the spinal column, though it has not been proved
upon what part of the side of the medulla the line of demarca-
tion exists. The deep lateral fissure, where the posterior roots
of the nerves emerge, has been assumed as dividing each half of
the spinal marrow into a posterior column, and an antero-lateral ;
the posterior made up as experiments upon living animals would
seem to show, wholly of fibres of sensation, and the latter com-
posed on its front part exclusively of fibres of motion ; the fibres on
the back part of the latter or antero-lateral column adjoining the
posterior roots of the nerves, belonging to the column of sensation.
We are therefore justified in considering with Solly and other
recent writers, that the line of division between the fibres of sen-
sation and those of motion, though unmarked, exist somewliere
in the middle between the two orders of roots of the nerves.
The absence of any tnarked line of division between the motorial
and sensorial columns, being no evidence against this view, as
nervous fibrils, when in juxtaposition have no intercommunication.
— ^The two lateral fissures cannot well be traced up on the sides
of the medulla oblongata, in consequence of their being oblite-
rated by some curved transverse fibres,* concave on their up-
per part, which seem to come from the corpora pyramidalia,
and run over to the cerebellum. But a division of the medulla
upon the side exactly between the roots of the nerves, extended
upwards by tearing, in parts that have been prepared for dis-
section, has a tendency to separate between the corpus olivare
and the corpus innominatum. From this it may be considered
probable, that all in front of this division, forms the motorial
column, and all behind it the sensorial. For facility of de-
scription, however, it is best to take the posterior median fis-
sure as the line of division, and treat of the posterior column
and the antero-lateral column.

* These fibres have been called arciform or bow-shaped, by Santorini and
Rolando ; and by Solly, the cerebeller fibres of the anterior columns. But the
observations of Cruvielhier, render it probable, that these fibres come from the
vertical septum of the medulla, described and figured by Sir C. Bell, in the
T «r>M„n Philos. Trans, for 1834.

48*

570 THE CORPUS RESTIFORME.

— The corpus restiforme, is continuous with the posterior column
of the cord, enlarges as it ascends, and gradually recedes from
its fellow of the opposite side, and turns backwards and out-
wards, to throw itself into the cerebellum, of which it forms the
inferior part of the crus, e fig. 224. The cavity left by this
divergence seen only on the upper part of the medulla oblongata,
forms a part of the fourth ventricle, (sinus quadratus,) and is in
its shape resembling the letter V ; the posterior median fissure
extended through it, gives it the appearance of the nib of a pen,
and it was therefore called the calamus scriptorius, by Herophi-
lus. Part of the lateral portion called innominata, goes upwards
towards the cerebrum, and part may be traced backwards, ter-
minating insensibly on the sides of the corpus restiforme, and
going with it to the cerebellum. By cutting off the corpus res-
tiforme at the crus of the cerebellum, and stripping it downwards,
we separate the column of sensation from that of motion ; the
cavity of the fourth ventricle is then found expanded, and a mass
of cineritious substance is seen exposed at top of the calamus
called tuberculum cinereitm, ov fasciola cinerea by Wenzel, which
is continuous below, with the posterior horn of cineritious sub-
stance in the cord, and upon the sides with the corpus restiforme ;
the gray substance of which, is here increased in bulk exactly in
proportion with the increase of the corpus restiforme over the
posterior column of the cord.

— The antero-lateral column of the spinal marrow is continued
up over the anterior and lateral surface of the medulla oblon-
gata to the pons varolii, constantly increasing in size, and upon
it are developed the corpus pyramidale and corpus olivare ; a
part of its fibres though, as just observed, passing off towards
the cerebellum. Fifteen to eighteen lines below the pons varolii,
is seen in the anterior median fissure after the removal of the
pia mater which dips into it, a decussation of white fibres which
nearly obliterates the fissure, fig. 224. This crossing, is tech-
nically called the decussation of the pyramids, and is formed
of three or four bands of medullary matter which pass over
from each" anterior column to the opposite side, then run
upwards parallel with the median fissure, and constitute the

CORPUS PYRAMIDALE. 571

corpus pyramidale. All the constituent fibres of the motorial
part of the cord, do not share in the decussation. Those on the
front and on the back part of the column, making about two-
thirds of the whole, cross in bands one over another, like the
fingers of the two hands when obliquely interlocked, while
the middle fibres of each motorial tract, pass straight up
through the pons to the hemisphere of the brain of the same
side.* ^

— On tearing carefully the corpus pyramidale from above
downwards in a prepared organ, or separating it in the manner
of Cruvielhier by the aid of a jet of water, it will be found that
some of the decussating fibres are in contact with the gray
substance, and that the inner face of the pyramid, has a column
of gray neurine attached to it, which increases in bulk as it
approaches the pons, and near which it terminates abruptly;
this is considered as representing in position, a portion of the
anterior horn of the nucleus of the cord.

— The white fibres of the exterior, dip round the gray matter
at its abrupt termination near the pons, and thus form the groove
between the medulla oblongata and the pons, which is filled up
with a process of the pia mater.
— On the outer side of the pyramid is placed the

Corpus Olivare.

— This is a body of a ganglionic shape, formed interiorly of
a vesicle of cineritious neurine arranged in folds, which, accord-
ing to Burdach, is appended to the 'anterior horn of the gray
substance belonging to the cord. Hence this vesicle is filled
in its centre with white fibres, as well as covered on its outer
surface with the white fibres which belong to the exterior of the
medulla oblongata.

* The fact of the decussation of these fibres, which is now universally ad-
mitted, was first pointed out by Mistichelli in 1709. A decussation of the fibres
had been believed to exist somewhere; as early as the time of Hippocrates and
AretSBUs, in consequence of injuries of one side of the head, producing very
generally, palsy of the opposite side of the body. All the fibres not crossing,
we are enabled to comprehend, why palsy is sometimes, though very rarely
found to occur on the same side of the body with the cerebral lesion.

572 CORPUS OLIVARE.

— When cut through transversely as seen in fig. 221, page 565,
it presents a serrated appearance, hke the corpus dentattim
of the cerebellum, fig. 224, page 577. By the facility with
which the corpus olivare may be turned out from its position,
as shown in the dissection of Mr. Solly, it appears to be a
ganglionic mass, intruded as it were between the ascending
fibres of the medulla, and bulging them outwards. It forms
in many animals a large ]obe for the origin of the pneumo-
gastric nerves, and its office is considered by Mr. S. as
exactly analogous in the human systeui. It appears to send
up no fasciculus of fibres to the brain, except those that origi-
nate in the interior of its cineritious vesicle ; the so called olivary
bundle of fibres of Gall and Spurzheim, which are extended
into the brain, coming from the lateral part or the antero-
lateral column, called by Cruvielhier the corpus innominatum.
This has already been described, page 570, as sending off
one band of fibres to join the corpus restiforme ; the other is
continued up, behind and around the corpus olivare,* lined on
its inner or central face with cineritious substance, and which,
enlarging as it ascends, and passing over the upper surface of
the pons varolii, is expanded into the optic thalamus. The
latter band thus forms in its course the anterior wall of the
fourth ventricle, and is brought into view by brushing away the
tuberculum cinereum, or gray matter of that ventricle. This
band constantly increasing as it ascends, has been called the
fasciculus cuneatus, (Burdach,) and fasciculus of reinforce-
ment, as it is much mixed up with gray matter on its inner

* The corpus olivare was considered a ganglion by Spurzheim, Prochaska,
and Vic d'Azyr, though they did not attempt to determine its office. Solly con-
siders it the ganglion of the pneumogastric nerve, part of the fibres of which,
both from the result of experiments upon the ganglion, and from analogy with
its structure in the inferior animals, he believes to originate from it. He con-
siders it highly probable that it is a central point upon which is received the
organic sensations arising from the lungs, and from which emanates that
peculiar imperative power that the system of respiratory nerves conduct, and
by which they call the, muscles of respiration into action, without the agency
of the will. This is very probably the case in regard to a portion of the fibres
of the pneumogastriC; forming its reflex system of nerves ; other fibres in all
probability pass up into the brain, to constitute the cerebral sensiferous and
motorial portion of this nerve.

SULCI OR FISSURES OF THE CEREBELLUM. 573

face, from which it seems to derive no fibres. The arrange-
ment of the cineritious substance of the medulla oblongata, is
seen in fig. 220, e, page 560.

— It will thus be seen that the medulla oblongata, is very com-
plicated and intricate in its interior structure. It has been
variously described by different anatomists, and its structure is
not yet probably thoroughly understood. Its anterior or motorial
fibres appear evidently directed upwards towards the cere-
brum ; its posterior or sensiferous pass backwards and out-
wards as the corpus resiforme, (inferior peduncle of the
cerebellum) to the centre of the cerebellum, where it meets
with a cineritious mass, called the corpus dentatum. From
this point its fibres are radiated in increased numbers, to the
circumference of the cerebellum, from whence, they have been
considered by Foville as again reflected inward, returning nearly
upon the same course to be converged into the crus cerebelli
of each side, and continued onward to form a part of the
structure of the pons.

Of the Cerebellum.

— The cerebellum lies below the posterior lobe of the cerebrum,
in a cavity inclosed, below and behind by the sphenoid and
occipital bones, laterally by the petrous portions of the tem-
poral bones, and above by the tentorium. It measures trans-
versely at its greatest breadth, from three inches ten lines, to
four inches ; longitudinally in the centre, twenty lines ; either
lateral portion is about two inches long, and about sixteen lines
thick at its middle. The lateral parts are called hemispheres.
The central poriion, from being the first part of the organ de-
veloped in the inferior animals and in the human foetus, is
called the fundamental portion by Gall and Spurzheim.* It
consists of tvvo portions, the inferior and superior vermiform
processes, so named from the transverse ridges upon the sur-
face, which give them the appearance of a worm. The anterior

* Reil considered this central part, a general .commissure, but this is evi-
dently an error, for we find this part sometimes, constituting the whole cerebel-
lum, as in rabbits, where there are no lateral lobes to connect.

574

MEDULLARY STRUCTURE OF THE CEREBELLUM.

portion of the superior vermifonTi process is elevated, and is
called the monticulus.

— When viewed from above, the two hemispheres externally
appear circular, and at the place where they are joined to the
central portion are deeply notched before and behind. Hence
they form two fissures in tl>e median line ; one looking towards
the cerebrum, and receiving the tubercula quadrigemina, g, fig.
225, termed the semilunar fissure : the other backwards,
receiving the falx cerebelli, and is called the purse-like fissure,
from its narrowness at first, and its subsequent enlargement.
Reil, employs the term horizontal or lateral fissures, to desig-
nate those depressions which extend transversely across the
fore part of the cerebellum, and contain the processes or parts
of its crura passing to the pons varolii.*

— These fissures are continuous with the intervals between
the upper and under posterior parts of each hemisphere, which
extend as far as the purse-like fissure. Thus a deep furrow may
be traced all round each hemisphere dividing the cerebellum into
an upper and under portion. Each hemisphere has five lobes,
two on the upper, and three on the under surface ; these are
separated from each other by deep furrows or fissures, which
pass in to the central medullary nucleus, as seen in fig. 225, in
which is represented a vertical section of one hemisphere.
— Each one of these lobes, is subdivided, as we may see, into
a nun)ber of lobules, by a series of smaller furrows. These
are found on the periphery of the lobes, and on the sides of
the large fissures which separate the lobes from each other, and
each one of these lobules again is formed of a number of hori-
zontal leaflets. Each leaflet is composed of a folded layer of
cineritious neurine half a line thick on its outer side, and of a
medullary layer within. The cineritious coverings of the leaf-
lets are all continuous together, so that each hemisphere of the
cerebellum has a cortical covering of cineritious matter, with a
superfices equal to that of a sphere twenty inches in diameter,
but plaited and folded up in a compact mass, to suit the narrow
space in which it is lodged in the cranium.

^ * Reil, Mayor's Translation, Anat. and Med. Commentaries.

MEDULLARY STRUCTURE OF THE CEREBELLUM. 575

— The medullary matter contained in the leaflets of each lobule,
are radiations from a larger medullary mass at the base of the
lobule, called a twig. The medullary twigs of each lobe, are
derived in a similar way from larger white masses, called branches,
and the branches again form a large medullary mass in the cen-
tre of each lobe called the trunk. The whole of this beautiful
arrangement of the medullary matter, forms what is called fanci-
fully, the thuya, or arhor vita. If we trace these medullary
fibres again out in a reversed direction (that is from the centre of
each lobe of the cerebellum, towards the pons and medulla ob-
longata,) we shall find that anteriorly the trunk of the arbor vitae
or the medullary nucleus, advances towards the medulla oblongata,
inclosing laterally the fourth ventricle ; each trunk then divides
into three processes or pedunciiU ; one pair passes up as rounded
columns to the testes of the tubercula quadrigemina, and is
called the peduncle of these bodies, processus e cerebello ad
testes oblique or intercerebral commissure of Solly ; a second
pair to the medulla oblongata, (corpora restiformia,) and a third
pair, over the lower surface of the pons, called its peduncle or
the great commissure of the cerebellum. Under the term crus
cerebelli, all these three parts are commonly, though inaccurately
comprised. Between the inner borders of the two rounded col-
umns which go to the testes, and closely adherent to them, is
spread a thin layer called the valve of Vieusseus, valve of the
brain, valve of the cerebellum.. This so called valve, forms the
roof to the fourth ventricle ; when it is broken through, that
cavity is exposed.

— Each one of the lamina or leaflets of the lobes of the cere-
bellum, are susceptible of being unfolded in a properly prepared
part, and spread out so as to form a flat membrane, with a cine-
ritious covering on its outer side, and a medullary layer within,
consisting of parallel fibres, which can be traced down to the
central medullary twig of each lobule. The last part of the
stratum consists of coarse and curvilinear fasciculi, which con-
stitute the central mass of medullary matter of each hemisphere
(trunk of the arbor vitse,) fibres of which may be raised up in a
properly prepared cerebellum with the forceps, in fine filaments
the size of the thread of a silkworm.

576 CEREBELLUM.

— The fibres of the peduncle of the pons, that is, of the lateral
part of the crus cerebelli which forms the great commissure of
the cerebellum according to Reil,can be traced in the backward
direction, outwards and inwards, upwards and downwards, so
as to appear to go almost to every part of each hemisphere of
the cerebellum. The fibres of the corpus restiforme, when
isolated, appear to pass in a similar direction. A vertical sec-
tion of any part of the cerebellum, will show the arborescent
arrangement of the white matter, (fig. 225.) But a section to
exhibit the corpus dentatum, must be made at the inner side
and in the course of the fibres of the corpus restiforme, which
is in favor of the view of Gall, who considered the corpus
dentatum as a ganglion of reinforcement to the corpus resti-
forme, and called it the ganglion of the cerebellum.*
— We have followed Reil in the main, in his description of the
cerebellum, as it involves no theory in respect to its formation;
but it appears equally probable, that the views of Gall lately
elucidated by Foville, are equally correct ; viz. that the cerebel-
lum is developed by diverging fibres which proceed from the
corpus restiforme to the circumference of the organ, and then
are reflected inwards or converged to form the peduncle of the
pons, and that of the tubercula quadrigemina.
— From this description it will be seen that the medulla oblon-
gata, is formed of four plans of different fibres ; that of the cor-
pus pyramidale, that of the corpus olivare, that of the medullary
lamen of Sir Charles Bell, (corpus innominatum,) and fourthly,
that of the corpus restiforme. The first one is formed by the
anterior or motorial column of the spinal marrow exclusively ;
that is, of the column between the anterior roots of the nerves,
and the anterior median fissure. The second starts fiom the sano;-
lionic mass of the corpus olivare and seems to run up with the fibres
of the third bundle placed behind it. The third formed of one
half of what is considered the motorial part of the lateral column
of Sir C. Bell, (and which he considers the cerebral strands of

* The best method pf unraveling a lobe, is that of Reil. A portion about
an inch broad is to be cut out of a fresh cerebellum, and placed for twelve or
twenty-four hours in a weak solution of caustic potash, then in distilled water
for some hours more, and finally left from twenty-four to forty hours in pure
alcohol.

CEREBELLUM.

577

sensation,) and the fourth, formed of the posterior and sensorial
half of this lateral column, united to the posterior column of the
spinal marrow, which forms the corpus restiforme.
. Fig. 224 *

* Fig. 224, is a representation of the cerebellum, and a part of the base of
the brain, showing especially the course of the anterior columns of the spinal
marrow, to their termination on the hemispherical ganglia. A, A, Antero-
lateral column of the cord continued on to the hemispheres of the cerebrum.
B, Corpora pyramidalia, the decussating fibres of which are seen. C, Corpora
olivaria. D, Pons varolii. F, Crus cerebri, g, Anterior cerebral ganglion or
corpus striatum. H, Cineritious or cortical neurine of the hemispheres forming
■what have been called the hemispherical ganglia. 1, Cerebellum, a, Olfactory
nerve, b, Optic nerve ; on its outer side, I, I, are seen the white fibres expand-
ing into the base of the middle lobe, c. Fourth nerve, d, Sensory root of the
fifth pair of nerves, e, Roots of the facial and auditory nerves. /, Anterior
commissure, h, Eminentia mammillares ; on the left side the cineritious
matter is scraped away so as to show the origin of the fornix from it in front,
and a medullary band going on the inner face of the optic thalamus, i, to the
corpus geniculatum externum, from which the root of the optic nerve has been
cut. k, Trunk of the fifth pair as it emerges through the transverse fibres of
the pons, D, which form the commissure of the cerebellum. On the opposite
side, these transverse fibres have been removed, to exhibit the passing of the

VOL. II. 49

578 PONS VAROLII.

— The corpus restiforme, has been traced backwards into the
clneritious coating of the cerebellum, and there is much reason to
consider that its fibres form a doubling or reflection there, and
again come forwards as a part of the pons varolii. The other
three columns we can trace upwards through the anterior part of
the pons varolii, and crura cerebri, to the brain.

Pons Varolii.

— By dividing on the lower surface of the pons the transverse
fibres which come from the cerebellum to the depth of about
one-eighth of an inch on the middle line, and then scraping
them back towards the cerebellum, the fibres of the corpus
pyramidale will be seen advancing through the pons varolii,
emerging from the anterior or upper edge of this body, transvers-
ing the upper part of the crus cerebri, a part of the thalamus
opticus, and finally expanding into the corpus striatum g, to
concur in the formation of the lobes of the cerebrum. The
divergence of the two crura cerebri, forms the posterior bounda-
ries of the lozenge-shaped cavity of the base of the brain. The
fibres of the corpus pyramidale are separated from each other in
their course through the pons, by gray matter, and the fasciculus ap-
pears in consequence to increase in its breadth. According to
Tiedemann, the transverse fibres of the pons, forming what

fibres of the anterior column, from the corpus pyramidale, which begin to
diverge and to be reinforced.

On the left side, the brain being inverted, is seen a vertical section of the
cerebellum, made through the entrance into it of the corpus restiforme m, (Pos-
terior column of the spinal marrow.) w. Corpus dentatum or ganglion of the
cerebellum, showing the augmentation of the corpus restiforme in the ganglion,
and from which the medullary branches and twigs divide to the leaflets of the
cerebellum. The whole of this medullary arrangement, constitutes the arbor
vitffi. 0 0, Nervous fibres cut ofi", whicli spread out from the thalamus into the
convolutions of the middle lobe, p, Medullary fibres which pass through the
corpus striatum, reinforced as they proceed to the anterior lobe. The middle
lobe of the brain on this side is entirely removed, which exposes the side of the
^reat lateral ventricle, q. In front of it a small section of the anterior lobe is
seen, and the fibres which radiate into that lobe from the thalamus and corpus
striatum. E, Inner termination of the fissure of Sylvius, from which the
middle lobe has been cut, showing its proximity to the corpus striatum in the
central part of the brain. 5, Fourth pair of nerves, i t, Anterior lobe of the
cerebrum, u, Middle lobe, v, Posterior lobe. On the right side, just below the
corpus olivare, are seen the arciform fibres of Santorini. In front of e is seen
the auditory and facial nerves.

COURSE OF THE ASCENDING FIBRES THROUGH THE PONS. 579

has been called the commissure of the cerebellum, are seen in
the foetus, to form a junction with the ascending fibres of the
corpus pyramidale.

- — The fibres composing the anterior half of the lateral column
(corpus innominatuin) ascending principally to the outer side
or back part of the corpus olivare, plunge into the pons varolii,
from the floor of the fourth ventricle, and pursue their course
through the crus cerebri, F, fig. 224, to their appropriate gan-
glion in front, the posterior cerebral, a, a, better known under
the name of thalamus nervi optici. These fibres form the
upper part of the crus cerebri, and are separated in that
body, from the ascending fibres of the corpus pyramidale, by
a deposit of dark-colored cineritious matter, called the locus
niger of Soemmering. This tract, which is considered sensory
by Bell and Solly, and motory by Foville,* is covered above
where it forms the upper part of the crus cerebri by the
valve of Vieussens, and the tubercula quadrigemina g. The
course of these fibres through the posterior cerebral ganglion
(thalamus) is not so distinctly marked, as those of the corpus
pyramidale B, fig. 224, through the corpus striatum, or ante-
rior cerebral ganglion ; they are more intimately intermixed
with the cineritious substance in the centre of the former.
From the outer side of this ganglion, the medullary fibres are
seen issuing forth, and spreading in every direction to terminate
in the cineritious outer covering of the cerebrum. The pons, it
will be seen then, as its name imports, is a sort of bridge
between the medulla oblongata, cerebrum, and cerebellum ;
formed of transverse fibres coming from the cerebellum particu-
larly well marked on the lower surface of the pons, of the
ascending fibres of the medulla oblongata, and of the processus
e cerebella ad testes or oblique commissure which passes on its
upper surface from each lobe of the cerebellum to the tubercula
quadrigemina, bodies which are placed on the back of the pons.
Included within these parts immediately below the valve of
Vieussens which is spread between the two processes or oblique
commissures last mentioned, is the fourth ventricle, or ventricle
of the cerebellum, from which a canal called the aqueduct of
* Encephalon, Diet, de Med. et de Chir. Pratiques.

580 VALVE OF VIEUSSENS.

Sylvius or iter e tertio ad quartum ventriculum, is extended up
underneath the tubercula quadrigemina to the third ventricle,
which will be found between, and extending a little above the
crura cerebri. Among the white fibres constituting the pons, there
is likewise intermixed a considerable quantity of cineritious matter.

The Valve of Vteussens,

— Arises from the central or fundamental portion of the cere-
bellum and is extended upwards in the middle line to the lower
two bodies of the tubercula quadrigemina — the testes. It is
attached on each side to the processus e cerebella ad testis, form-
ing as it were a portion of the pons, and part of its fibres passes
under the tubercles to reach the thalami nervorum opticorum.
It has been confounded in description with the processus cere-
belli ad testes ; it ought rather to be called the processus cerebelli
ad cerebrum. It covers in its course the top and sides of the
fourth ventricle, is formed of a thin medullary lamen on its outer
or posterior face and of a delicate cineritious layer on its inner.
It received improperly the name of valve, from Vieussens ; from
the appearance it presented when its upper end was cut off, by
the system of horizontal slicing, with which this anatomist studi-
ed the brain ; its detached end there seeming to face down like
a valve to shut off the communication between the third and
fourth ventricle. The cineritious matter is thickest at the middle
portion of the valve, where its structure is least resisting, and
from whence arises tlie fourth pair of nerves.

The Crura Cerebri

— Formed in the manner already described, are cylindrical,
and closely approximated at their origin from the anterior and
upper part of the pons. They are about six lines long, and six
lines thick, and form the column of fibres, from which the hemis-
pheres of the cerebrum are developed. As they pass up they
recede from each other, in order to approach the middle of each
hemisphere, where they terminate in the corpora striata and
thalami nervorum opticorum. They flatten themselves as
they recede from each other, and leave necessarily a cavity
between them, which forms a part of the third ventricle. The

THE CEREBRUM. 581

commissure of the optic nerves bounds them in front, and the
triangular cavity left by their divergence is closed up below by
the tuber cinereum, (pons Tarini) which surrounds the base of
the eminentiae mammillares h, fig. 224. Into these latter bodies
passes a band of white matter, which comes from the corpus
innominatum or lateral portion of the medulla oblongata.

The Tubercula Quadrigemina,

— (Lobi optici of animals, see fig. 225,) are four tubercles
placed upon the top of the pons, upon which they rest by their
lateral borders, and form an arch over the aqueduct of Sylvius.
— They form two pairs ; the superior called the nates, the infe-
rior the testes. These bodies are rather small and rudimental
in man, but large in the inferior animals. Tliey contain in their
interior some cineritious matter, and are covered on their outer
surface, by medullary fibres. Their direction is obliquely for-
wards and upwards. The posterior tubercles or testes are the
smaller, nearly hemispherical in shape, and are separated from
the anterior by a transverse groove. This groove is crossed by
another in the antero-posterior direction, which separates the two
bodies of the right, from those of the left side.
— Upon the testes terminates the valve of Vieussens, the rounded
column of each side called processus e cerebella ad testes, which
form the lateral boundaries of the fourth ventricle, and a trian-
gular medullary fasciculus from the side of the pons, which may
be traced upwards from the fascia innominata of the antero-lateral
column. The fibres from these sources pass up through the
tubercles, appear to be reinforced in the gray matter there, and
expand into the optic thalamus of each side, with which the
nates is continuous in an oblique direction, though partially sep-
arated from it by a slight groove. From the anterior extremity
of the nates, part some medullary fibres, which form a thin layer
over the corpus geniculatum externum of the corresponding thala-
mus, to assist in the formation of the optic nerve. A similar arm
of medullary matter passes, into the thalami, from either testis.

Cerehntm.
— The cerebrum is that portion of the encephalic mass, which
49*

582 ANTERIOR AND POSTERIOR GANGLIA OF CEREBRUM.

occupies all the cavity of the cranium, with the exception of
the fossa, formed on the inferior portion of the occipital bone.
It forms, as it were, a sort of efflorescence or expansion on the
top of the spinal column, into the centres of which on each side,
{corpus striatum and thalamus opticus,^ we have now traced
all the fibres of the medulla oblongata and cerebellum. The
volume of the cerebrum, a structure which is peculiarly large
in man, is from eight to tv/elve times greater than that of the
cerebellum.*

— The corpus striatum, {anterior ganglion of the cerehrum,)
and the thalamus nervi optici, (posterior ganglion of the
cerebrum,^ receive the fibres which come upwards from the
spinal marrow, and are continuous with those from the cere-
bellum. The corpus striatum is placed in front and slopes
obliquely upwards, forwards, and outwards, in the direction of
the anterior and middle lobes of the cerebrum, and thus
receding from its fellow of the opposite side, contributes to
form the cavities called the lateral ventricles. It is about two
and a half inches long, about an inch broad at its anterior part,
and is terminated in a tail-like process behind, which embraces
the upper portion of the thalamus. The thalamus is placed
more posteriorly ; it is about two inches long and one broad,
and is sloped downward and backward in the direction of the
posterior lobes of the cerebrum, and the posterior part of the
middle lobes ; by receding from its fellow of the opposite side,
it forms the upper and lateral boundaries of the third ventricle.
It is covered with medullary fibres on its outer face, and pre-
sents four rounded elevations. Three of these are found at its
posterior extremity ; one is above the other two, and is called
the tuherculum posterius superius ; those below consist of the
corpus geniculatum internum, and corpus geniciilatum exter-
num ; and there is one in front called tuherculum ante-
rius. its interior is composed of cineritious neurine, which is
continuous between the organs of the two sides, forming the

* In three young subjects, Cruvielhier found the weight as follows : —

lbs. oz. oz.

Cerebrum, weighing 2 2 Cerebellum, 4^

(( (( O Q t« Cl

EXPANSION OF THE FIBRES INTO THE HEMISPHERES. 583

commissura mollis of the third ventricle. The corpus stria-
tum is cineritious on its upper surface, or that which presents
to the ventricle, and is made up in its interior of alternate
strata of cineritious and medullary neurine, which gives it
when divided vertically a striated appearance, from which it
has received its name. The cineritious neurine in both these
organs, is marked with white medullary lines, which Gall first
described as the origin of new medullary fibres reinforcing
those which come from the medulla oblongata, to be expanded
into the cerebrum. Hence he assigned to the corpus striatum
and thalamus, the names of ganglia of the cerebrum.
— From all points of the surface of these two ganglia, except
those which form the walls of the ventricles, medullary fibres
radiate in all directions, forming the solar rays or fan (even-
tail) of Vieussens, and the radiating crown of Reil. Many of
the fibres which emerge from the thalamus, pass also through
a portion of the corpus striatum, and seem bridled, as it were,
by the curvilinear band of white fibres called tenia striata which
is placed along the inner margin of the corpus striatum.
— The fundamental point in the anatomy and physiology of
the cerebrum, consists in determining the ulterior course of the
fibres which radiate from these two ganglia, corpora striata,
and thalami optici, in order to constitute the convolutions of
the cerebrum, and the various bands which connect the differ-
ent parts of the brain together. This has not yet been satis-
factorily accomplished.

— Gall and Spurzheim, have considered them as passing off as
bundles of diverging rays, in the form of inverted cones, to the
outer or cineritious covering of the hemispheres, (hemispherical
ganglia,) and that new fibres from the termination of these, or
the same reflected inwards, pass subsequently in an opposite
direction under the name of converging fibres to form the
commissures. Tiedemann and Foville, with at least equal
reason, have considered the hemisphere of each side as formed
of a layer of medullary fibres, in the form of a sac, the com-
mencing point of development of which as seen in the foetus,
is at the sides of the corpus striatum and optic thalamus ; the
fibres of the sac being covered on its outer face with the gran-

584 THE PINEAL GLAND.

ular cinerltious neiirine, and the whole folded and plaited, so
as to present on the exterior the appearance of sulci and con-
volutions, and to be susceptible of being packed away, in the
narrow compass of the walls of the cranium. In either view
of the case, each convolution will consist of four layers, two
exterior and cineritious, two interior and medullary : the latter
of which may readily be separated by a jet of water in the
middle line, so as to allow the doubling forming the convolu-
tion to be straightened out.

— The corpus callosum, or commissura magna cerebri, is
evidently formed in part by a layer of white fibres, which,
proceeding from the upper and outer margin of the thalamus
and corpus striatum, turns inwards and passes transversely
over to the middle line of the body, to unite in some way that
is not fully understood, with a similar band from the opposite
side ; forming an arch or vault over the thalamus and corpus
striatum, which constitutes the roof of the lateral ventricles.
The remaining part of the structure of the corpus callosum
consists of a more external and thicker layer of white fibres,
which evidently come in from the hemispheres of the cere-
brum, as may be seen in an attempt to separate these parts
from above outwards and downwards.

— On the top of the tubercula quadrigemina, is seen a small
conoidal mass of cineritious matter, called the pineal gland,
(conarium,) which usually after the seventh year of life, con-
tains some particles of gritty or sabulous matter. From it,
extends a small band of medullary matter called its peduncle to
each thalamus. . The use of this organ is not known. Descartes
considered it, absurdly enough, the seat of the soul, after other
uses had been found for the corpus striatum, fornix, and other
parts, for which at different periods the same high office had
been assigned. Solly is disposed to consider it with its peduncles
a commissure between the thalami, and which he calls the
pineal commissure. Above this body, and between the tuber-
cula quadrigemina and back part of the corpus callosum, is the
great lateral Jis sure of Bichat, where the pia mater covering the
cerebellum and posterior lobes of the cerebrum is extended into
the ventricles in the interior of the brain. A portion of it enve-

THE HIPPOCAMPUS. 585

lops closely the pineal gland, and is extended over the top of the
third ventricle, constituting the velum interyositum, and down
the middle cornua of the lateral ventricles, forming the 'plexus
choroides. At the bottom of the middle cornua, the plexus
choroides communicates with the pia mater lining the fissure of
Sylvius. The ventricular serous or arachnoid membrane, is a
distinct membrane having no communication with that on the
outer surface of the brain. The so called posterior commissure
of the third ventricle, is formed merely by the bulging forwards
of the white fibres of the nates, in consequence of the cineritious
developments within.

— The Fornix, {inferior longitudinal commissure,^ is extended
over the upper surface of the velum interpositum. It has the
shape of a vaulted roof, as its name imports, and forms the roof
of the third ventricle, and part of the lower surface or floor of
the two lateral. It arises by two rounded cords called the ante-
rior pillars or crura of the fornix, from the eminentia mammil-
lares (bulbce fornicis) two small rounded bodies that are found
at the basis of the brain, (see fig. 224,) medullary externally,
and cineritious within, and into which fibres extend both from
the ascending columns of the medulla oblongata, and from the
interior of the thalamus.

The course of each of these cords, is first forward, then up-
ward, and then backward, through the grey matter lining the
lateral walls of the third ventricle. The crura thus form two
semicircles, concave posteriorly, that shortly unite on the median
line, the back surface of which is free and unattached, while the
front convex surface, receives fibres from the anterior lobes and
from the under part of the great transverse commissure or corpus
callosum, by which means, a thin delicate partition is formed,
hetiveen the lateral ventricles, called septum- lucidum. The fornix
in its passage backwards and under the corpus callosum, to which
it is attached, spreads laterally, and at first is nearly of the width
of half an inch ; but afterwards becoming much wider, it de-
scends to be connected with the convolutions, first of the back
part, and afterwards of the inner and under part of the posterior
lobes. Two bands of white matter called the posterior pillars
or crura of the fornix, pass one on either side down into the mid-

I

586 THE COMMISSURES.

die cornua of the lateral ventricles. While tracing the fibres of
the fornix in this portion of their course, two projections are ob-
served which have received the absurd appellation of hippocam-
pus major and hippocampus minor, which are usually described
as distinct bodies, situated in the descending and posterior cornua
of the lateral ventricles. When carefully examined in a brain
that has been well hardened in alcohol, the hippocampus major,
will be found to consist of cineritious neurine, covered by a thin
layer of medullary fibres on its inner or ventricular face. This
cineritious neurine is a part of, and continuous with, the external
or cortical coat of the cerebrum. The hippocampus is a part of
a convolution. The medullary fibres come from the under part
of the cerebrum, in various directions, and being collected at the
inner edge of this body, form what have been usually called the
posterior pillars or crura of the fornix, or the tenia hippocampi,
but which we must regard merely as the posterior and descend-
ing extremity of the inferior longitudinal commissure. The
cineritious neurine over which the fibres of the fornix pass at its
anterior inferior, and posterior inferior extremities, is in fact but
a continuation of that neurine which forms a part of the hemis-
pheral ganglia ; that is, a part of the convoluted surface of the
brain, but in this situation covered by the inferior fibres of the
fornix or inferior longitudinal commissure. In this mode of in-
vestigation the real character of the hippocampus major becomes
manifest.

— The hippocampus minor, is in some respects analogous to
the hippocampus major, for it is formed by the projection at ,
the bottom of one of the fissures dividing the convolutions at
the inner side of the posterior lobe, where it is covered by the
posterior fibres of the longitudinal commissure. It differs from
the hippocampus major in this respect, that the projection is
caused by the central or medullary surface of the convolution,
and not by the deep doubling inwards of the two layers as is
the case in regard to the hippocampus major. It will thus
be seen that the fornix serves to connect together many
portions of the hemisphere of the same side, as the corpus
callosum does those of the opposite sides. Several other
commissures of less masnitude are described in the cere-

VENTRICLES. INFUNDIBULUM.

587

brum, viz. the middle commissure of the third ventricle
formed by the union of the cineritious substance of the two tha-
lami ; the anterior commissure of the third ventricle, which
passes across between the corpora striata and the neighbor-
ing parts of the cerebrum, in front of the anterior crura of the
fornix, and which sends some filaments which arch forwards

Fis. 225.*

7 119 106 E

to the origin of the olfactory nerve ; the superior longitudinal
commissure described by Mayo as running along the sides of
tlie longitudinal fissure above the corpus callosum, to connect

* Fig. 225, is a vertical section of the cerebrum, cerebellum and medulla
oblongata. A, Anterior lobe of the brain. B, Middle lobe. C. Posterior lobe.
Z), Cerebellum. £, Medulla spinalis, i7, Medulla oblongata. JT, Pons varolii.
L, Crus cerebri. /, Section of the corpus callosum, which is situated at the
bottom of the fissure, separating the two hemispheres of the brain, g, Optic
thalamus, of which the back part only is seen. The corpus striatum is placed
in front of it, though not seen in this figure, and at the bottom of the dark space
which forms the lateral ventricle. Below the thalamus is seen the section of
the lubercula quadrigemina, (the superior eminences of which are called the
nates, the lower, testes,) and below that again the valve of Vieussens ; which
arises from the medullary layer of the central portion of the cerebellum, D.
Below the corpus striatum is the lateral ventricle. Between the optic thalamus
and the crus, is seen the third ventricle; (the fornix which separates these two

5bo ORIGIN OF THE ENCEPHALIC NERVES.

together the convolutions placed above that part ; and the
intercerehral commissure or valve of Vieussens, which has already
been described. A laterel view of the different parts of the
brain, is seen in the vertical section opposite, as well as the
position of the ventricles, the channel of communication between
them, and the relative position of the encephalic nerves at
their origin.

Where the brain is reversed, we observe at its base a deep
fissure, which separates the anterior from the middle lobes. This
is called the Fissure of Sylvius, and lodges the lesser wings of
the sphenoid bone, and the middle cerebral artery. By tracing
this fissure outwards, we fall upon an isolated cluster of five or
six convolutions, called the Islmid of Reil, which forms the
bottom structure to the corpus striatum.

— At the inner end of the fissure of Sylvius, is a triangular plane
of medullary matter, pierced by blood-vessels, which run into
the corpus striatum ; it is called the substantia perforata.
Immediately behind the optic commissure, and in front of the
eminentia mammillares, is found a small mass of grey matter,
called the tuber cinereum, which forms part of the floor to the
third ventricle.

— The infundibulum is a funnel-shaped reddish cineritious cord,
two and a half lines long, which seems to spring from the tuber
cinereum at the base of the third ventricle, and terminates on the
pituitary gland. It presents an open cavity on the side of the
third ventricle, and in the foetus communicates with the cavity
in the gland ; after birth its inferior extremity appears to be

ventricles, and the septum lucidum have been removed.) Between the tuber-
cula quadrigemina and the pons is the aqueduct of S3ivius, or the passage from
the third ventricle to the fourth, which forms the cavity, m. between the cere-
bellum and the medulla oblongata. 1, Olfactory nerve. 2, The eye, upon
which terminates the optic nerve, the root of which may be traced back, over
the crus cerebri to the optic thalamus, and the nates. Next below the optic is
seen the third pair of nerves, motor oculi. 4, The fourth pair running to the
superior oblique muscle of the eye. 5, Superior maxillary branch of the fifth
pair. 5', Ophthalmicbranchof the fifth pair. 5", Inferior maxillar)' branch of
the fifth pair. 6, Sixth pair, or motor externus. 7, Facial or portio dura;
below the origin of this is seen the trunk of the auditory nerve, or portio mollis.
9, Glosso-pharyng'eal. 10, Pneumogastric. 11, Hypo-glossal. 12, Spinal
accessory of Willis. 14, 15, Cervical nerves. The ophthalmic ganglion is
seen near the eye at the outer side of the optic nerve.

ORIGIN OF THE ENCEPHALIC NERVES. 589

closed. Some medullary fibres have been traced from it to the
optic nerve. It is closely embraced by the pia mater.

Between the eminentia mammillares, in front, the pons Varo-
lii, behind, and the crura cerebri on the sides, is found a layer
of whitish gray matter, called the pons Tarini, or locus perfora-
tus. It forms a bridge between the parts above mentioned, so
as to aid in closing the bottom of the third ventricle, and is
perforated by several thick tufts of arteries which are distributed
in the optic thalami.

— The Pituitary gland or hypophysis cerebri, is a small body
weighing about ten grains, placed in the cavity of the sella
turcica of the sphenoid bone, where it is closely embraced
upon its side and part of its upper surface, by the processes
of the dura mater forming the cavernous sinus, which mem-
brane is reflected into the cavity of the sella turcica, and forms
a capsule to the gland.

— It consists evidently of two lobes, an anterior and posterior,
as may be seen in the human subject. It is large, and may
be studied to advantage in the calf, where it forms a body
about an inch long, and five-eighths of an .inch wide. The
posterior lobe is about a third the size of the anterior, and
receives the apex of the infundibulum, through an oval opening
left in the dura mater. It is conoidal in front, and received in a
corresponding cavity of the anterior lobe, between which is
reflected a partition of very vascular cellular tissue from the side
of the capsule. The large lobe is cineritious and granular in its
centre, and medullary on its outer face.

— The posterior is of a grayish-white color, and presents two
eminences; one, which is continued forwards to the cineritious
centre of the anterior lobe, and one, which in the calf is evi-
dently fibrous and continuous backwards with the infundibulum.
The use of this organ is not understood ; in the human foetus, it
is larger at the fifth month of intra-uterine life than at birth. It
is proportionably larger in the inferior animals than in man, and
in fishes it forms a large lobe with a cavity in its centre. Wenzel
asserts that he has frequently found it diseased in epileptic sub-
jects ; and latterly Arnold has traced to it, several branches of
the sympathetic nerve which seem to originate from it.
VOL. II. 50

590 ORIGIN OF THE ENCEPHALIC NERVES.

On the Immediate Origin of the Encephalic Nerves.

— By reference to fig. 225, it will be seen that all the ence-
phalic nerves, (with the exception perhaps of the olfactory,)
originate from portions of the base of the brain, into which
has been directly traced the fibres of the spinal cord. It has
been shown that the nerves arising from the spinal medulla,
consist of two distinct classes, those of sensation and those of
motion : and that each nerve is, in all probability, composed in
part of filaments which, reflected at their origin from the gray
substance of the spinal cord, have no connexion with the
brain, and are called the reflex, or excito-motor ; and -partly of
those which are directly continuous with the brain, called the
sensiferous or cerebral. The encephalic nerves may be justly
considered as originating much in the same manner, with the
exception that their sensitive and motor roots, are, in general,
continued on as distinct trunks, to their termination in the organs.
— Their origin is derived in a great part from the medulla
oblongata, which contains a large amount of cineritious matter,
and from whence there is reflected a greater amount of nervous
fibrils, than from any similar bulk of the spinal cord ; some of
their fibres being also continued upwards to the brain, like the
sensiferous of the spinal cord. If it were possible to isolate dis-
tinctly the sensory from the motory fibres of the nerves, it
would be better to describe them in the direction in which they
act, the sensory from without inwards, and the motory from
the central organs towards the circumference. As this cannot
be done, they are considered from convenience of description,
as all originating from the central organs.

— The hypoglossal arises in the sulcus between the corpus
pyramidale and corpus olivare, by three roots placed in a line
with the anterior roots of the spinal nerves, which emerge by
a number of minute filaments from the anterior columns of the
medulla oblongata. It is a motor nerve.

— The spinal accessory of Willis, as has been observed, (page
464,) arises from the cervical portion of the spinal marrow.
— It commences from the lateral part of the cord, usually oppo-
site the fifth cervical vertebra, behind the ligamentum den-
ticulatum, and near the posterior roots of the spinal nerves.

ORIGIN OF THE ENCEPHALIC NERVES. 591

The nerve ascends on the side of the medulla, between the
ligament and the posterior roots of the nerves, and continues
to receive filaments of origin from the medulla as high up as
the roots of the pneumogastric with which the radical filaments
of this nerve seem continuous. It receives filaments as it
passes by, from the posterior root of the sub-occipital, and is
sometimes connected with the posterior root of the first proper
cervical. It passes up through the occipital foramen, and goes
out from the cavity of the cranium in conjunction with the par
vagum, with which it has been considered associated as a
motor nerve for the external respiratory muscles. It is a round
nerve like the third or the sixth.

— The pneumogastric or par vagum, is a mixed nerve in its
distribution, in consequence of its receiving motor filaments
from the spinal accessory and other nerves, which ^re wrapped
up in its general sheath. It is believed, however, to be a sen-
sory nerve, entirely, at its origin from the lateral tract of the
medulla oblongata, immediately behind the corpus olivare, where
it consists of from seven to fourteen flattened fasciculi.

The glosso-pharyngeal, is believed to be a compound nerve,
giving nerves of sensation to the mucous membrane of the back
part of the tongue and to the fauces, and nerves of motion to
some of the muscles of the pharynx. It originates by two roots,
which seem to come partly from the lateral tract, and partly from
the corpus olivare, immediately above the pneumogastric. It
has been considered the special nerve of taste ; but the nerve
of taste appears not to be a distinct trunk. The fibres endowed
with this function, are probably included in the branches of the
glosso-pharyngeal and the fifth. The three latter nerves, spinal
accessory, pneumogastric and glosso-pharyngeal make the eighth
pair of the old anatomists.

— The auditory nerve, (portio mollis of the seventh pair,) is ex-
clusively one of sensation ; it originates by two roots, one of
which passes through the substance of the medulla oblongata,
and takes its origin from the corpus restiforme. The other winds
round the restiform body, and arises from the medullary strife in
the cineritious substance of the fourth ventricle.

592 ORIGIN OF THE ENCEPHALIC NERVES.

— lihe facial nerve (portio dura of the seventh pair,) is con-
sidered the principal motor trunk to the fifth pair. It emerges
from the groove between the corpus pyramidale and olivare, but
may be traced backwards according to Solly, through the pons
varolii, to the inner side of, and in contact with, the sensory root
of the fifth pair of nerves. It then divides into two roots ; one
arising from the motor column of the spinal cord, and the other
from the cerebeller or arciform fibres of the anterior column (see
fig. 224.)

— The motor externus or abductor oculi (sixth pair) proceeds
from the anterior narrowed part of the corpus pyramidale, and
Is exclusively a nerve of motion.

— The trigeminus or fifth, is partly a mixed nerve, and arises
by two roots, one for sensation and one for motion. The former
called the portio major, constituting the great bulk of the nerve,
emerges, from between the transverse fibres of the pons varolii,
and can be traced down through the medulla oblongata, to the
posterior columns of the spinal cord, an inch and a half below
the pons. On the portio major, is formed exclusively the gang-
lion of Gnsser ; upwards of a hundred filaments have been
counted in this root.

— The motorial root, portio minor, traverses the pons by a dis-
tinct aperture and appears to originate from the antero-lateral or
motorial portion of the spinal cord. These motor fibres join the
third branch of the fifth pair, beyond the ganglion of Gasser,
and supply the muscles of mastication.

— The patheticus or fourth nerve, arises from the valve of Vieus-
sens, near the tubercula quadrigemina, where it is placed in close
connexion with other nerves going to the eye and its auxiliary
parts ; viz., the optic and the motor oculi communis.
— The motor oculi communis, or third nerve, emerges from the
inner side of the crus cerebri, but it takes its rise by two roots ;
one of which can be traced to the locus niger of the crus, and
is there continuous with the ascending motor columns of the
medulla oblongata ; the other passes round the outer margin of
the crus, just in front of the pons, and is closely connected with
that part of the origin of the optic nerve, nearest the peduncle.

BULB OF THE OLFACTORY NERVE. 593

This is called the accessory root of Rolando. It is particularly
well developed in the bullock. This nerve sends a large root
to the ophthalmic ganglion,, from which the ciliary nerves are
derived. It appears to be the motor nerve of the iris, for when,
in the experiments of Mr. ]\fayo, the third pair was irritated, the
iris was observed to contract.

— The optic or second nerve, the largest of all those of the
cranium, tracing it from its chiasm backwards, (where the
inner half of the fibres of each nerve seem to cross over to the
opposite side,) winds round the crus cerebri, to which it is
attached by a thin medullary lamen at its outer edge. As it
reaches the thalamus the nerve is divided into two roots, one
of which arises from the coi'jms geniculatum externum of
that organ ; the other passes over the corpus geniculatum
internum to which it is slightly connected, to arise by two slips
from the tubercula quadrigemina — one from the nates, and the
other from the testes. This latter is the principal origin of the
nerve in the inferior animals ; hence the tuberculi quadrigemina
have been called the optic tubercles.

— The olfactory or first pair of nerves, appears to originate
by three roots, near the fissure of Sylvius, close to the substance
of the corpus striatum. One of these is connected with the
anterior commissure of the middle ventricle ; and one with the
lateral prolongation of the corpus callosum at this part ; the
third or central root comes from a papillary eminence of the
cineritious structure in the posterior part of the fissure of Syl-
vius. The nerve formed by the union of these roots runs out
in a triangular groove on the lower surface of the anterior
lobes, to its bulb, by the side of the crista galli of the ethmoid
bone. The structure of the bulb is cineritious and pulpy
in man. In the inferior animals, as the horse and sheep, and
in the human foetus, it is of a similar structure, and forms a
large olfactory lobe with a ventricle within it, on the anterior
and inferior face of the brain. It would therefore in man be
more correct, as Blainville and Rolando have observed, to
consider the bulb as an olfactory lobe or ganglion, from which
the true olfactory nerves are spread into the Schneiderian
membrane, and the grayish cord extending back from it and
50*

594

DEVELOPMENT OF THE BRAIN IN THE F(ETUS.

j^

'M^.^

ordinarily called the nerve, as but a commissure to connect it
with the brain.* —

Development of the Brain in the Foetus.
In their course of development in the foetus, the spinal
Fig. 226.f marrow and brain present many

phases of structure, which cor-
respond to a considerable extent,
with the perfect forms of these
parts in many of the inferior ani-
mals. Two minute longitudinal
cords, with five pairs of gangli-
onic swellings at their upper or
anterior parts, constitute all that
exists of the cerebro-spinal axis in
a human embryo of seven weeks.

* The student will find his progress, in the difficult study of the nervous
system accelerated by the possession of preparations upon which the nerves have
been prepared and dried ; or what is next best, by drawings, which, at the same
time that they are kept in the main true to nature, give to the subject, some-
thing of the clearness of a diagram. In the latter respect, the student will
derive considerable assistance from the " Plates of the Cerebro-Spinal Nerves,
■with references," by Dr. P. B. Goddard ; in Manec's two plates, of the cerebro-
spinal axis, and of the sympathetic nerve, the size of life ; and in Professor
Lobstein's treatise, " De structura, usu, et morbis, nervi sympathetici," the
three last of which have been translated with additions, by the editor of this
work. Quain's anatomical plates which have also been issued under the super-
vision of the editor, by Carey & Hart, of this city, will be found to contain not
only a complete exhibition of the nerves, but of all the parts of the human body.

f Anatomic du Cerveau, &;c. par F. Tiedemann.
t Fig. 226.— A.

Side view of the brain and spinal marrow of a fcetus of seven weeks, a.
Hemispheres of the cerebrum, a'. Corpus striatum and optic thalamus, b.
Mass, from which is subsequently formed the tubercula quadrigemina. c. Ce-
rebellum, k. Spinal marrow enlarged at the top where it forms its bulb d.

B.

Brain of a foetus of twelve weeks, d. Spinal marrow, expanded and curved
above, forming the medulla oblongata, c. Cerebellum, below which is seen
passing one of the ascending cords of the medulla, b. Mass of the tubercular
quadrigemina. The crus of the cerebrum is seen directed downward and for-
ward, a. Hemispherical sac.

C.

Brain and spinal marrow of the same fcetus seen from behind, d. Medulla
spinalis, c. Cerebellum, a. Hemispheres of the brain, b. Mass of the tuber-
cula quadrigemina.

DEVELOPMENT OF THE BRAIN IN THE FCETUS. 595

This represents the condition of the brain in the lowest
class of fishes. Of these ganglia, (of which those of one
side are well shown at A, fig. 226 taken from the work of
Tiedeniann,) the two lower pairs represent the medulla oblon-
gata ; the two next above the lobes of the cerebellum ; the two
middle ones the mass of the tubercula quadrigemina which
is of larger size than any of the rest ; the fourth the optic
thalami or posterior ganglia of the brain proper, and the up-
permost of all, the copora striata, or anterior ganglia of
the brain, which are even so early as this covered over on
each side with a thin membranous sac, filled with fluid, and
constituting the rudimental hemispheres of the brain. These
parts are all curved upon each other, so as to correspond with
the direction of the future cranium.

— In the progress of development, the three lower sets of
ganglia speedily become united together on the median line,
leaving within cavities filled with fluid, continuous with each
other, connected behind with a canal formed in the same way in
the centre of the spinal marrow, and with a larger cavity in front
formed by the membranous sac of the hemispheres. This latter
cavity represents the common hollow of the ventricles, which as
yet, shows no mark of subdivision.

— A further step of development is seen at B, which is a
representation of the brain and spinal marrow of a fcEtus
of twelve weeks. The olfactory, the optic, and some other
nerves of the brain are now found connected with it, and the
spinal accessory is seen at the lower part. At this period of
growth it may be considered the type of the same parts, as they
exist in their perfect state, in the amphibia.
— At C, we have a view of the same foetal brain from its upper
aspect. The lower surface of the same parts would now
if examined, exhibit the crura cerebelli coming off" exclusively
from the medulla oblongata, and the crura cerebri, extended
beneath the mass distinguished as that of the tubercula quad-
rigemina, to the thalami and corpora striata. If the membra-
niform hemisphere be laid open from above, we see at the bot-
tom of the cavity the corpora striata, which are curved like an
arch round the crura cerebri, the fibres of which radiating for-

o96 DEVELOPMENT OF THE FffiTAL BRAIN.

wards and to the sides, form the hemispheres. On the front of
this cavity, will be seen already formed the anterior part of two
large commissures of the brain, the corpus callosum and the
fornix. On separating the two thalami, we find them as yet
not united at their middle parts so as to constitute the middle
commissure of the third ventricle, or commissure mollis. By
cutting into the mass of the tubercula quadrigemina, we find it
a sac ; the cavity of which opens below by a small orifice into
the fourth ventricle, which is continuous with that of the
medulla spinalis, and above has a similar communication with
the third ventricle.

— In the foetus of four months, the medulla spinalis is yet very
large in proportion to the bulk of the brain and encloses a
cavity with which the posterior and median fissures commu-
nicate. It is distinctly composed of longitudinal fibres and has
formed on its bulb or medulla oblongata little elevations, which
represent the corpus pyramidale and the corpus restiforme. Be-
tween these bodies a middle or lateral band is seen but on which
there is as yet no appearance of the corpus olivare. The cor-
pora restiformia which are extended backwards and outwards
on each side to form the cerebellum, have connected with
their cerebeller extremities the ganglion of the cerebellum or
corpus dentatum. The cerebellum is small and shows none
of its horizontal folds. The great hollow mass of the tubercula
quadrigemina has become altered in form, and contracted in
the middle, diminishing somewhat its great cavity, which is
subsequently to become a mere channel between the third and
fourth ventricles called the aqueduct of Sylvius. In front of
this contraction the small bodies forming the tubercula quad-
rigemina proper, begin to appear, and behind, the rudiment of
the pons varolii is visible. The thickness of the membranous
walls of this mass is about a line and three quarters behind,
but is not more than a third of a line in front. The hollow
hemispheres of the cerebrum, are considerably more developed
backwards and upon the sides, but as yet do not cover the
tubercula quadrigemina or the pons. On separating the two
sacs of the hemispheres, they will be found united in front so
as to form the front part of the corpus callosum, which is as

FffiTUS OF FOUR MONTHS. 597

yet but little developed. Below is seen the two anterior crura
of the fornix, which come up from the eniinentia mammillares,
unite slightly together, turn round the thalami, and subse-
quently diverging to form the posterior crura of the fornix or
corpus fimbriatum, are lost in the lower and posterior part of
the hemispheres. On the outer side of these crura there is a
doubling inwards of the walls of the ventricles, evidently in-
tended to form the hippocampus major, and a corresponding
elevation behind, the rudiment of the hippocampus minor. Tbe
great cavity in each hemisphere, which forms as yet but one large
ventricle, terminates in front in a canal which leads into the
cavity of the bulb. The anterior commissure not being formed
and the fornix as yet incomplete, there is no separation between
the middle and lateral ventricles. The larger part of this cavity
is filled up with the plexus choroides. The thalami are about a
quarter of an inch long and nearly two lines broad, and seem
placed as it were, as a bulbous expansion on the posterior ascend-
ing fibres of the crus cerebri. On their upper surface are seen
the peduncles of the pineal gland which unite together to form
that body.

— The corpora striata, are well formed and smooth, but do
not present the striated appearance when divided across.
— The cerebral hemispheres are about ten lines long and nearly
a quarter of an inch broad, and form two sacs, one over each
crus cerebri, which are as yet chiefly connected together by the
anterior portion of the corpus callosum, and the fornix. The
texture of the walls of these hemispheres is now plainly seen to
be fibrous on its inner face. On the outer surface the structure
though not fibrous, does not yet present any resemblance to
cineritious matter. The fibres from the anterior columns of the
medulla oblongata may be traced upwards and forwards; at first
they are covered and partially interlaid with the transverse fibres
from the cerebellum, that are to form in part the future pons
varolii ; two membranous processes are then detached upwards
on the back of the hollow mass known as that of the tubercula
quadrigemina, the larger portion of the fibres of the crus, passes
up through the optic thalamus ; some bundles of fibres descend
on the inner and lower side of the thalamus to the eminentia

m

598 DEVELOPMENT OF FffiTAL BRAIN.

mammillares, and all the remaining fibres which are still very
numerous, pass below the thalamus, and after sending up a band
into the corpus striatum, radiate like the branches of a fan into
the membranous hemisphere. These radiating fibres having gain-
ed the top, redescend in the middle line to reach the crura of the
fornix ; — some of the fibres of both hemispheres uniting at the
front to form the corpus callosum.

— The fibres described as descending to the eminentia mammil-
lares from the crura cerebri, mount upwards as the pillars of the
fornix, and are continued first backwards and then downwards
as the posterior pillars of the same body, to the bottom of what
is to become the middle cornua of the lateral ventricles. A sin-
gular and interesting connection is thus early seen in the
course of the fibres, which indicates the shape of the future
ventricles, and shows at the same time that the development of
the brain takes place in two directions.

— In the foetus of^ Jive months, we find the medulla spinalis
still tubular and capable of being inflated in a downward
direction from the fourth ventricle.

— The tube is expanded at the two enlargements of the
medulla, where the brachial and sacral plexuses of nerves have
their connection with it.

— No corpus olivare is yet developed. The cerebellum now
shows its divisions into central or fundamental, and lateral
portions, the latter of which cover over behind the bottom of
the fourth ventricle. The transverse fibres of tlie pons are
better developed, and the ascending stratum of fibres called the
valve of Vieussens, sent up by the pons to the tubercula quadri-
gemina, is well seen. The two hemispheres of the cerebrum
are prolonged more backward, and are about an inch and a
quarter in length. As yet they exhibit no convolution, except
at their internal and anterior part.

— The masses of the tubercula quadrigemlna do not yet present
the eminences called nates and testes.

— The corpus callosum and the fornix have increased in size,
and two thin lamina extend from the latter to the former,
forming the commencement of the septum lucidum. These
lamina have a ventricle between them, the fifth, that commu-

FffiTUS OF SIX MONTHS. 599

nicates with the third which is now provided with its anterior
commissure and the infundibulum.

— The walls of the hemispheres are very thin ; on laying them
open, the eminence analogous to the corpus striatum is found,
surrounded and imbedded as it were, in the ascending fibres of
the crus cerebri. It is not yet connected to the thalamus by
the band called tenia striata. The olfactory nerves are seen
arising in front from a hollow bulb, which communicates on each
side with the anterior cornu of the lateral ventricle. The optic
nerves come off partly from the mass of the tubercula quadri-
gemina and from the thalami. The dura and pia mater are now
well seen. In this stage of development, the brain of the foetus
resembles much the perfect brain of the lower mammalia. At
the sixth month the arachnoid membrane becomes apparent.
The hemispheres of the cerebrum are still smooth on their upper
surface, but much thicker and have extended so far backwards
as to cover the tubercula quadrigemina and the cerebellum.
The corpus callosum is so far developed backward, that the two
hemispheres can no longer be separated in the middle line so as
to expose the great ventricular cavity, without lacerating some
of the fibres of that commissure. The fourth ventricle or the
ventricle of the cerebellum is diminished much in size, the pons
has greatly increased, and the valve of Vieussens is marked
with the grey substance, forming the bands of Wensel. The
optic thalami are not united by their middle commissure. But
the anterior commissure uniting the two corpora striata together
has become apparent. At the seventh month, the cavity in the
medulla spinalis is found much diminished, and the inner face of
its walls is covered with a granular substance, closely adherent
to the pia mater which enters in at the median fissures. In the
region of the back the medulla is very narrow, not more than a
line in diameter, while it is double that size at the points at which
it is connected with the roots of the brachial and lumbar plexu-
ses. At the upper part of the medulla oblongata it is found
about four lines and a half in diameter.

— The cortical substance of the cerebrum has not taken its
proper cineritious hue, a result which is only effected after birth.
On the olivary or lateral fasciculus of this portion now appears

600

DEVELOPMENT OF FffiTAL BRAIN.

for the first time the corpus oUvare, consisting chiefly of a mass
of granular matter.

— Each lobe of the cerebellum is about an inch in breadth.
The hemispheres of the cerebrum have increased greatly in size
in proportion to the growth of the cerebellum and medulla.
They are extended even posteriorly to the cerebellum and are

Fig. 227.*

about two inches in length. On their upper surface the convo-
lutions have now become apparent ; but the walls are still very
thin, compared with the great size of the ventricles. The nates
and testes are conspicuous on the masses of the tubercula quad-
rio'emina, and in front of the eminentiae mammillares is seen the
pituitary gland.

— On opening the ventricles, the corpus callosum is found
developed backwards to its full extent, and enveloped in part
by a plane of fibres that comes from the outer side of the corpus
striatum and the thalamus. On the outer side of this plane and
in contact with it, another diverging layer which belongs to the
cerebral hemispheres passes up as an expansion from the crura
cerebri through the corpus striatum and the thalamus ; the fibres

* Left hemisphere of the brain with the radiation of the fibres seen after the
removal of the top portion of the cerebrum in a foetus of six months, a. Point
of radiation ; within, at this point but not seen, is the corpus striatum, b, b, b, b.
Fibres of the crus cerebri which radiate forward, bacliward and outward, c.
The radiating fibres of the periphery which cover on their outer face the pre-
ceding, and are overlaid themselves on the exterior with a soft granular cover-
ing, d. Fissure of Sylvius.

THE SPINAL MARROW. 601

of this layer pass up to the top of the brain, form a part of the
corpus callosum, and join with those of the opposite side. The
middle triangular portion of the fornix, called the lyra, is now
developed between the extended portions of its crura, and the
divisions of the ventricles are completely formed. The middle
commissure of the thalami, nor the tenia striata are yet plainly
shown. The foetal human brain presents at this stage of its
growth, very much the same appearance, that it has in the
animals nearest to man ; with the exception that in the foetal
brain the proportionate development of the cerebrum is much
greater.

— The cerebro-spinal axis may now be considered as completely
formed. The subsequent changes which occur during the eighth
and ninth months consist chiefly in its general growth, the
closing up of the cavity of the medulla spinalis with vascular
granular matter that after a time becomes ash-colored and forms
the nucleus of the medulla, and the development of the peri-
phery of the hemispheres, which having become too extensive
for the surface of the walls of the cranium, have their surfaces
folded inwards in the form of convolutions, so as to encroach
upon and nearly efface the cavity of the lateral ventricles. —

VOL. II. 51

GLOSSARY*

EXHIBITING THE DERIVATION OF CERTAIN ANATOMICAL

TERMS.

A.

Acetabulum, The cavity which receives the head of the thigh-bone ; from ace-
tum vinegar^ so called, because it represents the acetabulum or saucer of the
ancients, in which vinegar was held for the use of the table.

Acini. From acinus a grape.

Acromion. A process of the scapula ; from aKpo^ extremity, and ujnoi the shoulder.

Anastomosis. The communication of vessels with one another ; from ava through,
and jo/!o mouth.

Anatomy. The dissection of the human body ; from ava and tcjivo to dissect.

Anconeus. A muscle ; so called from ayKUf the elbow.

Aorta. Aoprr], from anp air, rnpioi to keep.

Aponeurosis. A tendinous expansion ; from ottcj, and vcvpov a nerve; from an er-
roneous supposition of the ancients, that it was formed by an expansion of nerve.

Apophysis. A process of bone ; from ajro^voj to proceed from. A synonyme of
process.

Arachnoides. A net-like membrane ; from apa^vrj a spider, and ciSo; likeness.

Artery. From arip air, r/jpcoj, to keep ; because the ancients supposed that air
only was contained in them.

Arthrodia. A species of connexion of bones ; from apdpocj to articulate.

Arytccnoides. The name of two cartilages of the larynx ; also applied to some
muscles of the larynx ; from ap-uraiva a funnel, and siJoj a shape.

Astragalus. A bone of the tarsus ; so called from its resemblance to a die used
in ancient games, from a^paXa a eockal or die.

Atlas. The first vertebra of the neck ; so called, because it sustains the head ;
from the fable of Atlas being supposed to have supported the world ; or from
arXao) to sustain, because it sustains the head.

Azygos. A term applied to parts without a fellow, from a priv. and fuyoj a
yoke, because it has no fellow.

B.

Bursa. A bag ; from livpua : generally applied to the bursse mucosae.

c.

Cancelli. Lattice work ; generally applied to the reticular substance in bones.
Cardia. The superior opening of the stomach ; from KapSia the heart.
Carotid. The name of some arteries of the neck and head, from Kapooi to cause to
sleep : for, if tied with a ligature, the animal was said to be affected with coma.

* By Dr. Hooper.

604 GLOSSARY.

Carpus. Kapnos ; the wrist.

ClavicuJa. The clavicle or collar bone, a diminutive of davis a key ; so called

from its resemblance to an ancient key.
Clinoid. Four processes of the sella turcica of the ethmoid bone are so called,

from (cXivj? a bed, and ci&oq likeness ; from their supposed resemblance to a couch.
Clitoris. A part of the female pudenda ; enclosed by the labia raajora ; from

K^tit,! to enclose or hide.
Colon. The first of the large intestines; from (cojXoi', quasi koiXov, from KoiXoi

hollow.
Coracoid. From Kopa^ a crow, and tiJos resemblance ; shaped like the beak of a

crow.
Coronary. From corona a crown. The vessels of the heart, stomach, (fee, are

so called because they surround the parts in the manner of a crown.
Cotyloid. From Korv^n the name of an old measure, and eiSos resemblance : re-
sembling the kotule.
Cranium. The skull ; Kpaviov, quasi, Kapaviov from Kapa the head.
Cremaster. A muscle so called ; from Kpcpaw to suspend, because it suspends

the testicles.
Cribriform. From cribrum a sieve, it being perforated like a sieve.
Cricoid. Annular, round, like a ring ; from KpiKog a ring, and siJos likeness.
Cuboides. A bone of the foot ; from Kv6oi a cube, and siSoi likeness ; because it

resembles a cube.
Cuneiform. Some bones are so called ; cuneus a wedge, and forma likeness, being

shaped like a wedge.

D.

Deltoid. A muscle resembling the Greek letter A : from A, and tiSoi resemblance.
Diaphragm. The muscle which separates the thorax from the abdomen ; from

ita<ppayroi to divide.

Diarthrosis. A movable connexion of bones ; from StapOpou to articulate.

Digastric. From 6is twice, and yasvp a belly ; having two bellies.

Diploe. The spongy substance between the two tables of the skull ; from SiirXou
to double.

Duodenum. The first portion of the small intestines ; so called because the an-
cients supposed that it did not exceed the breadth of twelve fingers ; from
duodenus, consisting of twelve.

Dura Mater. The outermost membrane of the brain ; called dura, because it is
much harder than the other membranes, and mater, from the idea of the an-
cients that it was the source of all the other membranes.

E.

Embryo. The child in the womb is so called before the fifth month, after which,
it is termed /ixiws ; from £^/?potj to bud forth.

Enarthrosis. An articulation of bones ; from tv, in, and apQpov a joint or articula-
tion.

Enteric. Belonging to the intestines ; from tvrtpov an entrail or intestine.

Epidermis. The scarf or outermost skin ; from m upon, and Stppii the skin.

Epididymis. The small oblong body which lies above the testicles ; from t-ai
upon, and StSvpoi a testicle.

GLOSSARY. 605

Epigastric. The superior part of the abdomen ; from cki upon, and yairip the

stomach.
Epiglottis. A cartilage of the larynx so called ; from tin upon, and yXumj the

aperture of the larynx, being situated upon the glottis.
Epipktjsis. A portion of bone growing upon another bone, but separated from

it by a cartilage ; from evi upon, and <pvcj to grow.
Epiploon. The membranous viscus of the abdomen, which covers the intestines.

and hangs to the bottom of the stomach ; from cimrXcio to swim upon.
Ethmoid, From £0//os a sieve, and etSos resemblance ; being perforated like a sieve.

F.

Fascia. An expansion, enclosing other parts, like a band, from /ascis a bundle.
Falciform. Shaped like a sithe; from /a/a;, a sithe.
Fasciculus. A little bundle, dim. oi fascis a bundle.
Fauces. The plural of faux, the top of the throat.

G.

Ganglion. TayyXiov, a knot in the course of a nerve.

Gastrocnemius. The muscle which forms the thick of the leg ; from yainp a belly,
and KVYj^v the leg.

Genio. Names compounded with this word belong to muscles which are attached
to the chin, as genio-glossus, genio-hyoideus, itc. ; from yevsiov the chin.

Ginglymus. An articulation ; from yiyyXvjioi a hinge.

Glenoid cavity. From y\rivr] a cavity, and eiJoj resemblance.

Glosso. Names compounded with this word belong to muscles which are at-
tached to the tongue ; as glosso-pharyngeus — glosso-staphylinus, &c. ; from
yX&jo-ffa the tongue.

Glottis. The superior opening of the larynx at the bottom of the tongue ; from
yXurra the tongue.

Glutaus. The name of a muscle : from yXaroi the buttocks.

Gomphosis. Toj^fuxn;, a species of immovable connexion of bones ; from yofKpoi;
a nail, because one bone is fixed in another bone like a nail in a board.

H.

Helix. The outward circle of the ear ; from ei\toi to turn about. ,

Hepar. The liver. ' HTrap an abdominal viscus.

Hyaloid. From i5aXoj glass, and tihi likeness ; the capsule of the vitreous hu-
mor of the eye is so called, from its transparent and glassy appearance.

Hymen. The membrane situated at the entrance of the virgin vagina; from
Yfirjv Hymen, the god of marriage.

Hyoiiles. A bone of the tongue, so called from its resemblance to the Greek v ;
from D, and siSoi resemblance.

Hypochondrium. That part of the body which lies under the cartilages of the
spurious ribs : from ino under, and ^ovSpoi a cartilage.

Hypogastric. The lower region of the fore part of the abdomen ; from vno under,
and yacrjp the stomach.

I.

Ileo7i. A portion of the small intestines ; from ei'Xtcj to turn, being always convo-
luted.

51*

606 GLOSSARY.

Ischium. The part of the OS innomiaatum upon which we sit ; from laj^yuio
sustain.

L.

Lacuna. The excretory duct of the glands of the urethra and vagina : from

lacus a channel.
Lamhdoidal sutjtre. So called because it is shaped like the letter A ; from A,

and £1^05 resemblance.
Larynx. The superior part of the windpipe ; Xapvy^ the larynx.

M.

MasseHr. A muscle of the face, which assists in the action of chewing ;

fxaaaaonai tO cliew.

Mastoid. From naaros a teat, and etSi; likeness ; shaped like a nipple or teat.

Mediastinum. The production of the pleura, which divides the thorax into two
cavities ; from medium the middle, quasi in medio stare.

Mesentery. The membranes to which the intestines are attached : from /iso-os
the middle, and cvrcpov an intestine, because it is in the middle of the intestines.

Mesocolon. That part of the mesentery in the middle of the colon ; from utaoi
the middle, and ko'Xov the colon.

Metacarpus. That part of the hand between the carpus and fingers ; from utra
after, and Kap-noi the wrist.

Metatarsus. That part of the foot between the tarsus and toes ; from utra after,
and rapooi the tarsus.

Mylo. Names compounded with this word belong to muscles which are attach-
ed near the grinders, as mylo-hyoideus, &c. ; from jivM a grinder tooth.

o.

Odontoid. Tooth-like ; from oJ*? a tooth, and tiSoi resemblance.

(Esophagus. The canal leading from the pharynx to the stomach ; from oiw to

carry, and ^ayco to eat ; because it carries the food into the stomach.
Olecranon. The elbow, or head of the ulna ; from uiy^svn the cubit, Kpaviov the head.
Omentum. An abdominal viscus ; so called from omen a guess, because the

soothsayers prophesied from the inspection of the part.
Omo. Names compounded with this word, belong to muscles which are attached

to the scapula, as omo-hyoideus, kc. from oj/^oj the shoulder.
Omoplata. The scapula or shoulder blade ; from to^o; the shoulder, and TrXaTws

broad.
Osteology. The doctrine of the bones ; from o^tov a bone, and \oyo% a discourse.

P.

Pancreas. A viscus of the abdomen ; so called from its fleshy consistence ; from

nav all, and Kpi:ai flesh.
Parenchyma. The substance of some of the viscera was so called, from iraptyKvo^

to pour through.
Parotid Gland. From -trapa near, and ovj the ear ; because it is situated near

the ear.
Pelvis. A bony cavity shaped like a basin ; from tcXvj a basin.
Pericardium. The membrane which surrounds the heart ; from itspi around,

and Kap&ia the heart.

GLOSSARY. 607

Pericranium. The membrane which covers the bones of the skull ; from rcpi

around, and Kpaviov the cranium or head. -
Periosteum. The membrane which surrounds the bones ; from -Ktpi around, and

oiMv a bone.
Peristaltic motion of the intestines ; from nepntWu to contract.
Peritoneum. The membrane lining the abdomen, and covering its viscera : from

ncpiTcivoi to extend around.
Phalanx. The bones of the fingers and toes are called phalanxes, from their

regular situation, like a <pa\ay^ or arrangement of soldiers.
Pharynx. A membranous bag at the end of the mouth; avo th (peptiv because

it conveys the food into the stomach.
Phrenic or diaphragmatic nerve, ^pevsi the diaphragm; from <ppriv the mind;

because the ancients supposed it to be the seat of the mind.
Pia Mater. The innermost membrane of the brain ; so called because it em-
braces the brain as a careful mother folds her child.
Pleura. The membrane lining the thorax ; TrXcvpa the side.
Plexus. A kind of network of vessels or nerves, from plecto, to weave together.
Psoas. A muscle so called ; from xpoa the loin, being situated in the loins.
Pterygoid process. From Trrcpv^ a pen or wing, and eiJoj likeness, so called from

its likeness to a pen or wing.
Pylorus. The lower orifice of the stomach, which opens into the intestines ;
■ from jrvXoco to guard an entrance, because it guards as it were the entrance of

the bowels.

R.

Raphe. A suture ; from paTrra to sew.

Penes. The kidneys, otto r« peiv, because through them the urine flows.

Retina. The net-like expansion of the optic nerve, on the inner surface of the
eye ; from rete a net.

Rhomboides. A muscle so called from its shape ; from pojiSos, a geometrical fig-
ure, whose sides are equal, but not right-angled, and tiJoj a likeness.

Rotula. The knee-pan ; a dim. oi rota a wheel, from its shape.

s.

Sacrum. A bone so called ; from sacer a word, because it was once offered in

sacrifices.
Salvatella. A vein of the foot, so called because it was thought that opening it

preserved health, and cured melancholy ; from salvo to preserve.
Sanguis. The blood ; airo r« aaeiv yvia, because it preserves the body.
Sartorius. A muscle, so called because tailors cross their legs with it ; from

sartor a tailor.
Scapha. The depression of the outer ear, before the anti-helix ; from (TKa<pij a

little boat or skiff.
Scaphoides. A bone of the carpus, so called from its resemblance to a skiff;

from 0Ka(i>ri a skiff, and eiSos likeness.
Sclerotic. A term applied to the outermost or hardest membrane of the eye ;

from (TK'Snpooj to make hard.
Sesamoid banes. From (tijoo^t; a grain, and siJoj likeness ; from their resemblance

to the semen sesami.

608 GLOSSARY.

Sigmoid. Parts are so called from their resemblance to ihe letter E ; from E,

the letter Sigma, and etSo; likeness.
Sphenoid. From cipnv a wedge, and etSoi likeness ; shaped like a wedge.
Sphincter. The name of several muscles, whose office it is to shut up the apert-
ure around which they are placed ; from (r^iyyco to shut up.
Splanchnic. From iy!T\ayxvoi an entrail.

Symphysis. A connexion of bones ; from avfitpvio to grow together.
Synarthrosis. A connexion of bones ; from cw with, and apdpov a joint.
Synchondrosis. A species of union of bones by means of cartilage ; from aw

with, and ■^ovipo; a cartilage.
Synneurosis. A species of connexion of bones by means of membrane ; from aw

with, and vevpo^ a nerve ; because membranes, ligaments, and tendons, were

by the ancients considered as nerves.
Syssarcosis. A species of connexion of bones by means of muscle ; from aw

with, and aap^ flesh.
Systole. The contractile motion of the heart and arteries ; from avuTcWa to

contract.

T.

Tmdon. From tcivu to extend.

Thorax. Qwpa^. The breast^or chest.

Thyroid- From dvpeoi, a shield, and etSo; likeness ; shaped like a shield.

Trachea. The wind-pipe ; so called from its roughness ; from rpaxvi rough.

Trochanter. A process of the thigh-bone, so called from rpoxos a wheel.

u.

Ulna. A name for the cubit ; from oXcvn the cubit.

Ureter. The canal which conveys the urine from the kidney to the bladder ;

from «pov the urine.
Urethra. The passage through which the urine passes from the bladder ; from

upov the urine.
Uvea. The posterior lamen of the iris, so called because in many animals it is

of the color of unripe grapes ; from uva an unripe grape.
Uvula. The conical substance which hangs down from the middle of the soft

palate ; so called from its resemblance to a grape. A dim. of uva a grape.

V.

Valves. From valves, folding doors.

Vertebra. The bones of the spine are so called : from verto to turn.

X.

Xiphoid. So called from the resemblance to a sword ; from |i^of a sword, and
eiSas likeness.

z.

Zygoma. The cavity under the zygomatic process of the temporal bones ; from
^vyoi a yoke.

INDEX.

A

Antihelix, i
Antitragus, i

i 450
i 450

Abdomen,

ii

13

Annulus abdominalis,

i 328

contents of.

ii

15

cruralis, »

i 329

Abdominal muscles,

326

Antrum Highmorianum, •

i 88

regions,

ii

16

Aorta, i 514 i

i 240

ring,

328

Aponeurosis pal maris,

i 364

Abductores vide muscles.

plantaris,

i 391

Absorbents, general anatomy

Apophysis,

i 52

of.

ii

332

Appendix to the diaphragm.

i 343

origin of,

ii

337

vermiformis, i

i 54

glands.

ii

343

Appendices epiploicae, i

i 58

termination.

ii

346

Aqua labyrinthi, i

i 472

of the lower ex-

Aqueductus cochlea3.

i 69

tremities.

ii

351

vestibuli.

i 69

of the abdomen

Sylvii, i

i 386

and thorax,

ii

352

Fallopii,

i 69

/ of the intestines

ii

356

Aqueous humor, i

i 445

of the head and

Arachnoidea tunica, i

i 373

neck.

ii

264

Arbor vitas, i

i 388

of the upper ex-

Arch, femoral.

i 329

tremities.

ii

365

Arciform fibres, i

i 569

Absorption, cutaneous,

ii

368

Arcus senilis, i

i 413

Acetabulum,

i

169

Arthrodiae,

i 53

Acini,

i

78

Arteries, structures of, i

i 210

Adductores vide muscles,

form of, i

i 221

Attachment of the lungs.

498

distribution of, i

i 240

Adipose tissue.

408

acromialis, i

i 271

Air cells,

523

adipose, i

i 291

Alimentary canal.

ii

27

alveolar, i

i 256

Alveoli,

104

Anastomotica, i

i 303

Alveus communis.

ii

469

anterior tibial, i

i 304

Ampullae,

ii

468

aorta thoracica, i

i 281

Amygdalae,

474

abdominalis, i

i 283

Analysis of bone,

23

articular of the knee, i

i 303

of cartilage,

38

articularis posterior, i

i 281

of muscle.

299

axillary, i

i 270

of brain.

ii

548

basilar, i

1 267

Angles, occipital and facial.

134

brachial, i

i 273

Anus, prolapsus,

ii

60

brevis, i

1 273

Ankle joint.

264

bronchial, i

i 281

blU

INDEX.

Arteries, buccinator,

256

Arteries, iliac internal,

294

carotid common,

246

ileo colic.

289

external,

247

lumbar.

295

internal ,

259

infra orbital,

256

cavernous,

261

innominata.

242

carpi radialis,

275

intercostal superior,

269

centralis retinas,

261

inferior.

282

cerebelli inferior,

267

interosseal.

276

superior.

267

internal plantar.

307

cerebral, ii 268 and

264

maxillary,

254

cervicalis anterior.

269

mammary.

265

posterior,

269

ischiatic,

298

ciliary,

262

lingual.

248

circumflex anterior,

272

laryngeal.

248

posterior,

272

lachrymal,

261

ilei,

300

lateralis nasi,

250

humeri,

272

labial is inferior,

249

femoris.

302

lumbar.

292

coccygeal,

298

mammary external,

271

corporis callosi.

264

mesenteric superior,

288

coeliac,

285

inferior,

289

colic, media and dex

-

malleolar.

205

tra.

ii

287

mediastinal,

266

communicans cerebri

,ii

263

meningea anterior or

coronaria dextra,

ii

287

parva.

ii

254

labiorum.

ii

249

media or magna

' ]]

254

ventriculi.

ii

286

posterior,

267

cystica.

ii

387

metacarpal,

275

dental or maxillary in-

metatarsal,

307

ferior.

255

nasal.

257

digitales man us,

277

obturator,

296

pedis.

307

occipital.

250

dorsalis linguae.

249

oesophageal.

ii

281

penis.

298

ophthalmic.

ii

261

emulgent,

291

palatine superior.

ii

257

epigastric,

300

palpebral.

ii

253

ethmoidal.

262

pancreatic.

ii

287

facial or external max-

pancreatico-duodena

-

illary,

ii

249

lis,

ii

287

femoral,

ii

301

palmaris profunda.

ii

275

frontal,

ii

263

perforantes,

ii

303

gastric, inferior,

ii

289

peroneal.

ii

306

gastro-duodenalis.

ii

287

pharyngea superior,

ii

257

gastro-epiploica dex-

inferior.

ii

250

tra,

ii

287

phrenic.

ii

284

sinistra.

ii

287

plantaris externa,

ii

307

gluteal.

ii

297

popliteal.

ii

303

haemorrhoidal middle

,ii

297

profunda femoris,

ii

302

superior.

ii

299

humeri.

ii

273

hepatic.

ii

286

pterygoidea,

ii

256

humeral.

ii

273

palatine superior,

ii

257

helicinae.

ii

180

pterygo-palatine.

ii

257

iliac common.

ii

293

pudic external,

ii

301

external or hy-

internal.

ii

298

pogastric,

ii

299

pulmonary.

ii

329

INDEX.

611

Arteries, piloric,

286

Articulations of the fingers,

i 255

radial,

274

of the ribs,

i 255

ranina,

249

of the hip joint,

i 257

recurrens radialis,

274

of the knee.

i 259

ulnaris,

275

of the tibia and

tibialis.

305

fibula,

i 263

renales,

291

of the ankle joint,

i 264

sacralis media,

293

of the tarsus and

laterales.

295

metatarsus.

i 266

scapularis superior.

269

of the toes.

i 267

internal.

271

Arytenoid cartilages.

i 478

spermatic,

291

Auricles of the heart.

i 505

spheno-palatine,

257

spinal.

283

B

splenic,

287

stylo-mastoid,

251

subclavian.

264

Base

of the brain, ii 389

sublingual,

248

of the cranium, ii 125

submaxillary or inf.

255

Bile,

ii 105

submental.

249

Biliary ducts, ii 102

subscapular,

271

Bladder urinary, ii 127

superficial cervical or

Blooc

, colormg matter of, ii 235

ascending.

266

crassamentum, ii 234

supra-orbital,

262

serum, ii 233

supra-renal.

291

globules of, ii 237

supra-scapular,

269

Bones, general anatomy of.

i 13

tarsal.

ii

305

number of,

i 14

temporalis, anterior

Gerdy on.

i 25

and posterior,

ii

252

Deutsch and Miescher

profunda

ii

255

on the microscopical

thoracicae externae.

ii

271

structure of,

i 30

thyroidea inferior.

ii

266

formation and growth,

i 40

superior.

ii

248

Astragalus,

i 212

tibialis antica.

ii

304

atlas,

i 142

postica.

ii

306

calcis,

1 213

transversalis cervicis

ii

266

carpus,

i 191

faciei.

ii

353

clavicle,

i 175

perinei.

ii

299

coccyx,

I 152

tympanica.

ii

253

costoe.

155

ulnar,

ii

275

cuboid,

215

umbilical.

ii

395

cuneiform,

216

uterine,

ii

297

ethmoides, ]

75

vertebral.

ii

266

femur,

201

vesical.

ii

296

fibula.

207

Articulations in general,

ii

232

frontal, i

61

of the head.

ii

239

humerus,

181

of the vertebrae.

ii

241

hyoides, i

118

of the lower jaw

, i

244

ileum.

164

of the clavicle

innominata, i

163

and scapula,

ii

245

ischium, i

166

of the OS humeri

,i

246

lachrymal, i

90

of the elbow.

i

248

malar, i

91

of the wrist,

i

250

maxillary superior, i

86

of carpal and mc

-

inferior, i

96

tacarpal bones

,i

254

metacarpus, i

196

612

INDEX.

Bones, metatarsus,

i 217

Canaliculi lacrymales, i

nasal,

i 89

Callus, formation of

naviculare,

i 214

Canthi, i

occipital,

i 72

Capsulae suprarenales, i

palati,

i 92

Capsule of Glisson, i

parietale,

i 64

Caput gallinaginis, i

patella.

i 209

Cardia, i

phalanges manus,

i 199

Cardiac plexus, i

pedis,

i 219

Cartilages, structure of

pisiform.

i 195

temporary and per-

pubis.

i 167

manent.

radius,

i 188

accidental develop-

Sacrum,

i 151

ment of

scaphoides,

i 192

Caruncula lacrymalis, i

scapula,

i 177

myrtiformes, i

semilunaris,

i 193

Casserian ganglion, i

sesamoid,

i 221

Caudae equina, i

sphenoid.

i 79

Cavity of the cranium.

sternum,

i 160

thorax.

tarsus.

i 211

abdomen, i

temporal ,

i 66

nose,

tibia,

i 205

mouth,

trapesoides,

i 193

Centrum ovale, i

turbinata.

i 95

Cerebellum, i

ulna,

i 186

Cerebrum, i

vertebra; true,

i 138

Ceruminous follicles, i

false.

i 151

Cervical ganglia, i

vomer.

i 95

Chordae tendinae,

wormiana or triquetra,

i 57

Chorda tympani, i

of the ear, i

i 460

Choroidea, i

stapes, i

i 460

Choroid plexus, i

malleus, i

i 460

Cellular membrane,

incus, i

i 460

Qilia, i

Blood vessels, general anato-

Ciliary ligament, i

my of, i

i 207

body, i

capillary, i

i 223

processes, i

Brain, general account of.

i 371

vessels and nerves, i

membranes.

i 372

ganglion, i

special description of.

i 558

Ciliary epithelium,

development of.

i 594

Clitoris, i

analysis of i

i 548

Circle of Willis, i

Bursae mucosae,

i 275

Circulation foetal, i

Bronchia,

i 517

Chyle, globules of i

glands of

i 518

comparison with blood

Brunners glands,

i 71

and lymph, i
Chromato genous apparatus.

C

Cochlea, i

Calamus scriptorius.

li 570

Colon, i

Caecum,

li 53

Columnae carneae,

Calices renales,

ii 121

Commissura magna cerebri, i

Canalis Fallopii,

i 69

anterior, i

of Fontana, .

ii 414

posterior, i

of Petit,

ii 439

media or mollis, i

Canals of Havers,

i 29

Conglomerate glands, i

Canalis arteriosus.

ii 205

Coni renales, i

INDEX.

613

Coni vasculosi, ii
Conjunctiva, ii
Corium, i
Cornea, ii
Comu ammonis, ii
Cornua of the ventricles, ii
Corona glandis, ii
Coronary vessels v. arteries.
Corpus pampiniforme, ii
callosum, ii
striatum, ii
pyramidale, ii
olivare, ii
restiforme, ii
cavernosum penis, ii
vaginae, ii
spongiosum urethrae, ii
fimbriatum, ii
papillare, i
highmorianum, ii
luteum, ii
Corpora albicantia, ii
quadrigemina, ii
Corpuscles of bone and carti-
lage, i
of the spleen, ii
of the kidney, ii
Corpusculum arantii, i
Cortical portion of the brain , ii
of the kidney, ii
substance of the teeth, i
Cotyloid cavity and ligament, i
Cowper's glands, ii
Cricoid cartilage, i
Crystalline lens, ii
Crura eerebelli, ii
cerebri, ii
penis, ii
Cutis vera, i
Cuticle, i
Cupola, ii

D

148
398
425
412
385
382
162

143
381
382
391
171
170
159
188
162
385
389
147
196
390
336

44
111
122
509
329
120
102
169
158
426
411
390
390
160
411
430
467

Dartos, ii

140

Desmoid tissue, i

223

Derma, i

426

Dentition, aberration of, i

117

Diaphragm, i
Diapnogenous apparatus, i
Digital cavity, ii
Diplos, i

343
426

382
18

Diploic sinuses, i

55

Ductus comunis choledochus, ii

104

Wirsungii, sue pan-

creaticus, ii

107

Whartonianus,

472

Bartholini,

472

Stenonianus,

469

arteriosus Botalli,

ii

205

venosus,

ii

205

e tertio ad quartum ven-

triculum.

579

brachio cephalic,

367

ad nasum.

404

hepaticus,

102

cysticus,

103

prostaticus,

156

thoracicus.

ii

360

Duodenum,

47

Dura mater.

ii

371

E

Ear, external.

449

drum of,

453

labyrinth,

456

lymph.

473

calcarious concretions,

473

nerves.

477

function,

480

Ejaculatory duct.

155

Elastic tissue,

229

Enamel,

112

Enarthrosis,

51

Encephalic nerves.

485

Ensiform cartilage.

162

Eminentise mammillares,

390

Epidermis,

430

Epidydimis,

140

Epigastric region,

16

Epiglottis,

477

Epiphysis,

15

Epiploon,

25

Epithelium, cylinder,

65

tesselated,

64

Erectile tissue,

164

Eustachian tube,

458

Eye, orbit of.

127

ball of,

108

auxiliary parts.

397

humors of,

445

measurement.

447

manner of dissecting.

447

Eyelids,

398

Eyebrows,

397

Excito motory nerves,

556

Extremities, bones of sup..

174

inf.,

201

F

Face,

85

YOL. II.

52

614

INDEX.

Fascia superficialis abdomi-
nis, i 331
lata, i 329
of the pelvis, or iliac, ii 176
of the perineum, ii 172
Fallopian tubes, ii 193
aqueduct, i 69
Falx cerebri, major and mi-
nor, ii 375
Fauces, i 474
Femur, i 201
Femoral ring, i 329
Female organs of generation, ii 183
Fenestra ovalis and rotunda, ii 454
Fibrous tissue, i 223
Fasciculi and fibres of mus-
cles, i 280
Fibro-caitilage, i 230
Fingers, i 199
Fimbria, ii 194
Fissures of the liver, ii 88
of the orbit, i 120
Foetus, head of, i 135
trunk, i 173
thorax, 1 526
extremities, i 221
heart, i 529
lungs, i 532
abdomen, ii 202
face, i 136
circulation of, ii 204
Follicles, sebaceous, i 413
muciparous, ii 72
of Lieberkuhn, ii 71
of Boehm, ii 67
Fontanelles, i 136
Foot, articulation of the, i 264
Foramen ovale, i 537
ccecum, i 467
of Winslow, ii 62
Fornix, ii 383
Fossa ovalis, i 506
navicularis, ii 163, ii 450
Fourchette, ii 184
Fraenum vulvas, ii 184
praeputii, ii 171

G

Galactopherous ducts, i 495

Gall-bladder and duct, ii 103

Ganglia, general anatomy of, ii 551

sympathetic, ii 530

cervical, ii 534

thoracic, ii 537

Ganglia lumbar, ii

sacral, ii

semilunar, ii

Ganglion of Arnold, ii

lenticular, ii

of Casser, ii

of Meckel, ii

otic, ii

ophthalmic, ii

Gastric liquor, ii

Generation, male organs of, ii

female organs of,ii

General anatomy of the bones, i

of fibrous tissue, i

muscular tissue, i

serous membranes, ii

mucous membranes, ii

ligamentous tissue, ii

erectile tissue, ii

alimentary canal, ii

sanguiferous system, ii

arterial, ii

venous, ii

absorbents, ii

Gimbernat's ligament, i

Ginglimus, i

Glands, general anatomy of, ii

parotid,

submaxillary,

sublingual,

pineal,

pituitary,

prostate,

thymus,

thyroid,

Cowper's,

lymphatic,

mucous,

lacrymal,

meibomii,

of Tyson,

of Peyer and Brun

ner,

Glandulae Pachioni,

epiglottidea,
agminatae,
solitarias,
Glans penis,

clitoridis,
Glissons capsule,
Globules of the blood,
of the chyle.
Glottis, ligaments of,

chink and ventricle of,
Gomphosis,

540
541

538
530

487
488
491
477
487

88
138
183

13
223
279

20

63
229
178

27
209
209
229
232
326

53

77
469
471
472
387
38G
156
526
487
158
343

71
403
401
170

73
377
480

75

74
162
184
101
237
238
479
481

53

INDEX.

615

Graafian vesicles, ii 196

Gubernaculum testis, ii 203

Gumes, i 459

H

Hairs, structure of, i

bulb and color, i

Halitus, ii

Hand, v. bones and muscles.

Havers glands,

Head, dimensions of,

Heart, structure of
situation of
dimensions of
malformation of
action of

Hepatic duct,

lobules,

Helix,

Hip-joint,

Hippocampus major.

Hyaloid tunic.

Humor vitreous,

crystalline,

aqueous,

hyaloid,

Hottentots, peculiarity of

Humerus,

Hymen,

Hypochondriac regions,

Hypogastric,

441

444
21

235
132
511
216
217
533
226
102

98
450
257
385
438
437
442
445
438
185

81
186

18

18

Iteradquartumventriculum, ii 386
Iter ad infundibulum, ii 386

I

Ileum, ii 48

Incus, ii 460

Infundabulum of the cochlea, ii 467
of the pituitary

gland, ii 386

of the kidney, ii 121

Incisurae auris, ii 452

Inguinal region, ii 18

Integuments, i 403

Intestines, muscular coat, ii 41

villous coat, ii 42

villi of ii 69

division of, ii 45

small, ii 46

large, ii 53

follicles of ii 71

Interarticular cartilages, i 244

Intervertebral substance, i 241

Iris, ii 420

Isthmus faucium, ii 474

Ivory of the teeth, i 103

Jacob's membrane, ii

435

Jaw V. bones.

Jejunum, ii

48

Joints, Ugaments of the ankle, i

226

elbow, i

264

wrist, i

250

hip, i

257

knee, i

259

shoulder ,i

246

K

Kerkringius, valves of,
Kidneys, structure of,
Kiernan, researches of,

ii

119

ii

65

ii

95

Lacerti ligamentosi, i

I 240

Lachr3niial sac, i
duct, i

I 404
I 404

puncta, i
Lacteals, or lymphatic vessels, i
Lactiferous ducts, i

1 404
i 332
i 495

Labyrinth, L
Lamina cribrosa,

I 465
I 76

spiralis, i
Larynx, structure of,

i 467
I 476

Lateral ventricles, i

I 381

Leg,

Lens crystallina, i

Limbus luteus, i

I 264
i 441
1 433

Linea alba,

I 327

semilunaris.

i 328

Ligaments of the joints,
Ligamentum acromio-clavicu-

I 239

lare,

i 245

bicorne.

i 246

adscititum,

i 248

conoid.

i 246

coronary, i
cotyloid,
cricothyroidean,
cruciforme.

i 89
i 257
i 486
i 261

epiglottidean,
Gimbernat's,

i 486
i 328

Poupart's,

i 329

1

616

INDEX.

Ligamentum nuchae,

i

249

Mons veneris, i

i 183

orbiculare,

i

243

Morsus

diaboli, i

i 194

pubic,

i

273

Motions of the skeleton.

i 397

rotundum s. te-

of the muscles.

i 287

res,

i

258

Motor tract, i

i 569

round or umbi!

i-

Monticulus cerebelli, i

i 574

cal,

ii

90

Mouth,

cavity of.

i 458

subclava,

i

242

Mucous

membranes, i

i 63

suspensorium I

e-

follicles, i

I 72

patis,

ii

90

glands, i

I 75

penis,

ii

167

Muscular fibres,

I 823

radiated.

i

245

sheaths.

t 281

transversalis at

-

Muscles

, general anatomy of,

1 279

lantis.

i

240

of organic life,

I 280

triangular,

ii

173

analysis of.

I 298

trapesoid,

i

246

individual.

L 300

Lips,

i

306

abductor oculi.

I 305

Liquor Cotugni,

ii

469

pollicis manus.

371

Morgagni,

ii

442

digiti minimi

sanguinis.

ii

232

manus,

375

Liver, minute anatomy of.

ii

98

pollicis pedis.

393

Lobulus spigelii,

ii

88

indicis pedis.

395

quartus.

ii

89

medii digiti pedis, 396

Lungs, structure of

i

320

tertii pedis.

396

Lymphatic vessels,

ii

349

minimi pedis.

396

Lumbar regions,

ii

18

adductor oculi.

304

Lunula,

i

440

pollicis manus,
indicis,

372
375

M

minimi digiti,
magnus femoris,

373

376

Malleus,

460

pollicis pedis.

393

Mammae,

493

digiti medii,

395

Mastoid cells,

67

tertii,

395

Meatus auditorius externus,

452

minimi,

394

internus,

69

indicis.

395

Mediastinum anticum,

499

accelerator urinae.

337

posticum,

499

anterior auris.

371

Medulla oblongata,

391

attollens auris.

301

spinalis.

394

arytaeno-epiglotti-

of the boYies,

35

deus superior.

486

Medullary substance of the

inferior.

486

brain,

380

anconeus,

364

of the kidney

122

azygos uvulae.

320

lining membrane.

33

buccinator

309

neurine.

545

biceps, flexor cubiti.

362

Membrana pupillaris.

426

brachialis internus.

I 362

tympani.

454

biceps flexor cruris,

L 384

Membranous urethra.

168

corrugator supercilii,

1 300

Mesentery,

51

ciliaris.

303

Mesenteric glands.

356

compressor nasi.

306

Mesocolon,

61

crico-thyroideus,

307

Metacarpus,

196

constrictor isthmii fau

-

Metatarsus,

217

cium, I

309

Mitral valves,

510

constrictor pharyngis

Modiolus,

466

inferior, i

320

INDEX.

617

es, constrictor pharyngis

Muscles, genio glossns.

315

medius, i

320

gluteus maximus,

377

superior, i

320

medius.

378

cremaster, i

336

minimus,

378

coccygeus, i

348

gemelli,

379

complexus, i

353

gracilis,

387

coraco-braciiialis, i

361

gastrocnemius,

388

cruralis, i

383

hyoglossus.

315

crico-arytasnoideus

intercostales extern

i,i

324

posticus, i

484

interni

) ^

324

lateralis, i

484

iliacus internus,

347

depressor labii supe-

interspinales,

358

rioris, i

308

intertransversales,

358

anguli oris, i

308

infraspinatus,

3.59

labii inferioris,i

308

indicator.

370

digastricus, i

314

interosseous.

374

dartos, i

336

levator palpebrae

deltoides, i

360

super.

i

303

erector penis, i

336

anguli oris,

i

307

clitoridis, i

340

labii super.

extensor carpi radi-

alaequenasii

307

alis longior, i

368

labii inferioris,

309

brevior, i

368

scapulae,

354

ulnaris, i

369

lingualis,

317

digitorum commu-

longus colli,

321

nis, i

369

levator ani,

340

metacarpi pollicis, i

370

latissimus dorsi.

350

primi internodii, i

370

longissimus dorsi.

352

pollicis minor, i

370

lumbricales.

372

pollicis pedis, i

385

levator tympani

longusdigitor.ped.i

386

major.

ii

462

brevis, i

391

minor.

ii

462

flexor carpi radialis, i

365

masseter,

311

ulnaris, i

365

mylohyoideus.

315

sublimis perfo-

multiftdus spinae

355

ratus, i

366

occipito-frontalis,

300

profundus per-

orbicularis palpebrarum,!

302

forans, i

266

oris,

310

longus pol-

obliquus superior oculi

) f

305

licis, i

367

inferior,

305

flexor brevis pollicis, i

371

descendens abdominis,

326

parvus digit.

ascendens.

332

minim., i

373

capitis superior.

357

longus digitor.

inferior.

357

pedis, i

390

omo-hyoideus,

316

pollicis,!

390

obturator.

348

brevis digitor.

opponens pollicis,

371

ped. i

291

obturator externus,

377

digitor. acces-

pterygoideus internus,

312

sorius, i

392

externus

)i

312

brevis pollicis

platysma-myoideus.

313

pedis, i

393

palato pharyngeus,

319

digit, mini-

pectoralis major,

323

mi, i

394

minor,

323

genio hyoidius, i

315

pyramid alls,

335

52*

\

618

INDEX.

, psoas niagnus, i

346

parvus, i

346

palmaris longus, i

864

brevis, i

371

pronator teres, i

365

quadratus, i

367

prior indicis, i

374

annularis, i

374

medii, i

374

posterior indicis, i

374

annularis, i

375

medii, i

375

pectinalis, i

376

pyriformis, i

378

popliteus, i

384

peroneus longus, i

387

brevis, i

387

tertius, i

386

plantaris, i

389

quadratus lumborum,i

346

femoris, i

380

retrahens auris.

recti oculi, i

304

rectus capitis

inferior, i

322

lateralis, i

322

abdominis, i

334

capitis posticus, i

356

femoris, i

382

rhomboideus, i

351

sterno-cleido-mas-

toideus, i

314

sterno hyoideus, i

316

thyroideus, i

316

stylo glossus, i

317

hyoideus, i

317

pharyngeus, i

318

salpingo -pharyn-

geus, i

320

subclavius, i

323

serratus anticus, i

324

posticus su-

perior, i

352

posticus in-

ferior, i

351

sphincter ani, i

338

vaginae, i

341

splenius, i

351

spinalis dorsi, i

352

semi-spinalis dorsi, i

354

colli, i

356

sacrolumbalis, i

353

scalenus anticus, i

357

medius, i

357

posticus, i

357

Muscles, supraspinatus, i 359

subscapularis, i 361

supinator longus, i 367

brevis, i 369

sartorius, i 381

semitendinosus, i 383

semimembranosus, i 384

soleus, i 389

stapedius, ii 463

temporalis, i 311

thyrohyoideus, i 317

triangularis sterni, i 325

transversalisabdom. i 333

transversus perinasiji 337
trapezius or cucul-

laris, i 348

trachelo-mastoideus,i 354

transversalis colli, i 356

teres major, i 360

minor, i 360

triceps cubiti, i 363

femoris, i 376

tensor palati, i 818

vaginae, i 880

tibialis anticus, i 385

posticus, i 390

transversalis digitor, i 396

pedis, i 396

thyreo arytasnoideus,! 485

epiglotticus, i 485

tensor tympani, i 462

vastus externus, i 382

internus, i 382

zygomaticus major, i 310

minor, i 310

N

Nabothi ovula, ii 192

Nails, i 440

Nares, posterior, i 449

Nates of the brain, ii 886

Neck of the Bladder, ii 134

Nervous system, general

view of ii 481
Nerves, origin of ii 482
structure of ii 483
of the brain, ii 485
of the spinal marrovr,ii 564
ganglionic, ii 529
, general anatomy of ii 543
functional division of ii 549
primitive filaments of ii 547
excito-motory or re-
flex, ii 553

INDEX.

619

Serves, connection with the

Nerves, sympathetic.

528

spinal cord.

564

cranial ganglia of,

532

origin of encephalic

566

Neurileraa,

547

1st pair, olfactory,

485

Neurine, cineriteous,

544

2d optic.

486

medullary,

545

3d motor oculi

)^^

486

analysis of.

548

4th pathetic.

487

Nipple,

495

5th trigeminus

488

Nymphae,

185

6th abducens,

496

0

7th acoustic and

Obliquus ascendens v. mus

-

facial,

ii

496

cles.

8th pneumogas

-

CEsophagus,

ii

28

trie,

ii

499

Omentum,

ii

61

9th hypoglossus

jii

505

Ophthalmic ganglion.

ii

487

cardiac.

ii

535

Orbit of the eye.

i

120

glossopharyngeal.

ii

499

Orifice of the urethra,

ii

186

vagus,

ii

501

of the stomach.

ii

32

accessory of Willis

ii

504

Ossification,

i

40

vidian,

ii

492

Ossa v. bones.

recurrent,

ii

502

Os tineas.

ii

193

phrenic.

ii

510

Otoconie or otolithes.

ii

473

ciliary,

ii

490

Ovaries,

ii

195

descendens noni.

ii

506

Ovula Graafiana,

ii

196

ganglionic,

ii

528

Nabothi,

ii

192

median.

ii

513

P

palatine.

ii

491

nerygoid.

ii

492

Palatum mollis.

461

ingual or gustatory

,ii

494

Papillae renales,

ii

123

anterior auricular.

ii

495

conoidal,

465

tympanic (Jacob-

filiform.

465

son's)

ii

501

majores.

465

cervical.

ii

507

of the skin,

425

suboccipital.

ii

507

Parietal v. bones.

auricularis, magnus

ii

508

Parotis,

469

superficialis colli,

ii

508

Pancreas,

105

communicans noni.

ii

509

Pelvis, cavity of.

171

external respiratory

, ii

512

dimensions of.

173

ulnar,

ii

515

of the kidney.

121

radial or musculo-

Pelvic fascia,

177

spiral,

ii

516

Perineal fasciae,

173

great intercostal.

ii

528

Perichondrium,

36

interosseus.

ii

516

Pericardium,

502

cutaneus internus,

ii

516

Periosteum external.

32

perforans Casseri,

ii

513

internal.

33

musculo cutaneus,

ii

513

Pericranium,

56

obturator,

ii

Peritoneum,

22

crural.

ii

Penis,

158

ischiatic.

ii

Peyer's glands,

73

tibial.

ii

Pes anserinus.

499

sacral.

ii

Pes hippocampi.

385

peroneal.

ii

Pharynx,

490

splanchnic.

ii

538

Phalanges,

199

iris sympathetic :

Pinna,

449

nerves of,

ii

532

Pia mater.

373

spermatic,

ii

540

Pineal gland,

ii

387

620

INDEX.

Pituitary gland,

i 386

Round ligaments,

ii

190

Pigmentum nigrum, i

i 417

Rotula or patella,

i

209

Placenta, i

i 206

Rugffi,

ii

188

Pleura,

i 498

Rete vaginae or plexus reti

-

Plica semilunaris,

i 407

formis.

ii

188

Plexus pulmonary,

i 503

brachial, i

i 511

cardiac.

i 536

S

lumbar.

i 502

solar,

i 538

Sabatier on fcetal circulation

, i

535

hypogastric,

i 540

Sacs of the vestibule.

ii

469

renal,

i 539

Sacculus laryngus.

481

spermatic.

i 540

sphericus,

ii

469

choroides,

i 384

hemisphericus.

ii

469

Plexuses of the sympathetic, :

i 539

Salivary gland.

469

Pons varolii.

i 89

Scala tympani,

ii

468

Tarini, i

i 390

vestibuli.

ii

468

Pomum adami.

i 477

Sclerotica,

ii

410

Portal vein, i

i 323

Scalenus, v. muscles.

Portio dura and mollis, i

i 392

Scrotum,

139

Poupart's ligament,

i 328

Sebaceous glands.

413

Prepuce, i

i 170

Semilunar valves.

510

Prostatic gland.

i 156

Septum scroti.

139

Processus vermiformis,

i 54

narium.

123

Promontary or pyramid, i

i 460

pectiniform.

160

Protuberantia annularis.

i 389

pellucidum,

384

Pulse, of the, :

i 288

cordis,

505

Puncta lacrymalia, i

i 404

Serum of the blood.

203

Pupil, i

i 420

Serous tissue.

20

Pulmonary vessels, i

i 329

Semicircular canals,

468

Pylorus, i

i 32

Schneiderian membrane.
Sinus lateral,

torcular Herophyli,

453
376
377

R

longitudinal,
occipital,

ii
ii

376

378

Radius v. bones.

petrous,

ii

378

Raphe scroti, i

i 139

cavernous,

ii

377

corporis callosi, i

i 381

circularis of Ridley,

ii

377

Receptaculum chyli, i

i 362

sphenoidal,

78

Rectum, i

i 58

Valsalvae,

509

Reflex nerves, i

i 553

of the nose.

457

Renal capsules i

I 117

venous of the heart,

564

Rete mucosum,

I 415

Skeleton,

54

Reticular membrane,

I 408

Skin, structure of,

411

Reticulated tissue of bones,

I 16

Spheno-maxillary fissure,

122

Regions, abdominal, i

I 17

ganglion.

ii

491

Retina, i

I 430

Spine, curvature of,

139

Retinacula morgagni, i

I 57

Spinal marrow.

ii

394

Ribs, movement in respirat.

165

nerves.

ii

566

true and false.

I 165

Spermatic cord.

ii

141

Rimi glottidis.

t 487

Spleen,

ii

107

Ring, crural.

I 327

Spongy part of the urethra,

ii

165

abdominal.

I 331

Spot of Soemmering,

ii

433

Right auricle.

I 505

Stapes,

ii

460

ventricle,

I 507

Stomach, fibres of.

ii

35

INDEX.

621

Submaxillary gland, i 470

Sublingual gland, i 470

Superciliary ridges, ii 397

Sutures, i 57

Subcutaneous capsules, i 238

Syndesmology, i 223

Synovial capsules, i 234

sheaths, i 238

Taenia semicircularis, ii 383

hippocampi, ii 385

Tapetum lucidum, ii 418

Tarsus of the eylids, ii 399

Tela choroidea, ii 387

Teeth, composition of, i 100

alveoli, i 107

development, i 110

permanent, i 113

Tensor v. muscles.

Tendons, general anatomy of, i 287

Tentorium, ii 375

Testicles, ii 138

Testes of the brain, ii 386

Thalamus nervi optici, ii 382

Throat, i 474

Thoracic duct, ii 360

Thorax, cavity of, i 497

Thyroid gland, i 487

cartilages, i 477

ligaments, i 478

Thymus gland, i 527

Tongue, structure of, i 462

Tonsils, i 474

Tragus, ii 450

Trachea, i 517

Trigonum vesicae, ii 135

Trunk, ii 137

Tuba Eustachii, ii 457

Tuber annulare, ii 389

cinereum, ii 386

Tubercula quadrigemina, ii 386

Tubuli uriniferi, ii 123

seminiferi, ii 148

Tunica conjunctiva, ii 400

sclerotica, ii 409

albuginea, ii 408

adnata, ii 401

elythroida, ii 142

vaginalis communis, ii 144

testis ii 144

albuginea testis, ii 145

arachnoidea, ii 473

hyaloidea, ii 438

Tunica Jacobi, ii 435

Ruyschiana, ii 419

Tympanum, cavity of, ii 453

U

Ulna, v. bones.

Umbilicus, ii 14
Umbilical fissure, ii 87
ligament, ii 90
vessels, ii 204
region, ii 17
Urachus, ii 202
Urinary organs, ii 1 17
bladder, ii 127
Ureters, ii 126
Urethra of male, ii 161
length of, ii 167
of female, ii 199
Uterus, ligaments of, ii 190
fibres, ii 192
cavity, ii 192
changes during preg-
nancy, ii 203
Utriculus, ii 469
Uvea, ii 422
Uvula, ii 461

Vagina, ii 186

Valves of the veins, ii 231

of the absorbents, ii 235

Valve of the colon, ii 57

of Bauhin, ii 56

Botal, i 530

Eustachius, ii 507

Vieussens, ii 389

semilunar, i 509

tricuspid, i 507

mitral, i 510

of Thebesius, i 507

Valvulae conniventes, ii 41

Vasa recta, ii 148

efferentia, ii 148

vorticosa, ii 416

Vas deferens, ii 153

Veins, structure of, ii 229

distribution of, ii 310

bronchial, ii 315

vesicales, ii 826

pulmonary, ii 828

Uterine, ii 198

vertebral, ii 315

Vena cava superior, ii 812

inferior, ii 825

azygos, ii 312

622

INDEX.

Vena portarum, ii 323

Vein, axillary, ii 319

basilic, ii 320

cephalic, ii 319

coronary, ii 311

capsular, ii 324

circumflex, ii 327

emulgent, ii 325

external iliac, ii 327

internal iliac, ii 326

epigastric, ii 326

saphena major, ii 328

minor, ii 328

femoral, ii 317

galeni, ii 388

hepatic, ii 322

hypogastric, ii 326

superior intercostal, ii 314

inferior, ii 313

primitive iliac, ii 326

jugular external, ii 318

internal, ii 316

lumbar, ii 325

sacral, ii 325

mesenteric, ii 224

phrenic, ii 322

subclavian, ii 318

splenic, ii 324

spermatic, ii 325

Velum pendulum palati, ii 462

interpositum, ii 387

Ventricles of the heart,
of the brain,
of the larynx,

Verumontanum,

Vertebrae, v. bones.

Vestibule,

Vesicula seminalis,
graafiana.

Villous coat.

Villi of the tongue,
of the stomach,
of the intestines,

Vidian nerve.

Vitreous humor.

Vocal ligaments,

Vulva,

Ventriculus succenturiatus,

W

11

507
381
480
164

466
154
196
66
465
37
42
ii 492
ii 437
481
ii 183
ii 47

Weber, measurement of the

capillaries, ii 226

Wrist, V. bones.

Zona ciliaris,
ossea,
coriacea,
membranosa,
vesicularis,

ii 440

ii 467

ii 467

ii 467

ii 467

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