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TREATISE
ON
SPECIAL  AND  GENERAL
ANATOMY.
BY  WILLIAM E
M
ER,  M. D.
ADJ. FBOF. ANAT. UNIV. PENNSYLVANIA--MEMBER OF THE AMERICAN PHIL.
      SOCIETY--SURGEON AT THE PHILABELPHIA ALMS HOUSE, &C.
Multum adhuc restat opeiia, multumque restabit, nee ulli nato, post mille tteculn
praecluditur occasio aliquid adjiciendi."
                                        SENECA, EPIST.
IN TWO  VOLUMES,  f   /^T""^^!?^
      VOL,. II.
^EC'OND  EDITION,  REVISED AND CORRECTED
      tfhitetelplifa:
CAREY &  LEA.
1830. 
Q4     ,

    v.a
Eastern District of Pennsylvania, to wit:

********  BE IT REMEMBERED, that on the seventeenth day o£
% seal. *  October, in the fifty-first year of the  Independence of the
********  United States of America, A, D.  1826—William E. Hor-
ner, of the said district, hath deposited in this office the title of a book,
the right whereof he claims as author, in the  words following, to wit:

" A Treatise on Special and General Anatomy.  By William E. Hor-
  ner, M.D., Adjunct Professor of Anatomy in the University of Penn-
  sylvania—Member of the American Philosophical Society—Surgeon
  at the Philadelphia Alms House, &c.  ' Multum adhuc restat operis,
  multumque restabit, nee ulli nato, post mille sjecula prsecluditur oc-
  casioaliquidadjiciendi.'—Seneca, Epist.  In two volumes.  Vol.11."

  In conformity to the Act of the Congress of the United States, en-
titled, "An Act for the Encouragement of Learning, by securing the
Copies of Maps, Charts, and Books, to the Authors and Proprietors
of such Copies, during the times therein mentioned"—And also to the
Act, entitled, "An Act supplementary to an Act, entitled,  'An Act
for the Encouragement of Learning, by securing the Copies of Maps,
Charts and  Books, to the Authors and Proprietors of such Copies
during the times therein mentioned,' and extending the benefits there-
of to the arts of designing, engraving, and etching Historical andothcK
Prints.'"
                                     D. CALDWELL,
          »        Clerk of the Eastern District of Pennsylvania. 
A  TREATISE  ON  ANATOMY.
BOOK  IV.
                       PART II.

                Organs of Assimilation.

                     CHAPTER I.

             OF THE ABDOMEN GENERALLY.

   The cavity of the abdomen occupies the space between
the inferior surface of the diaphragm and the outlet of the
pelvis; a  considerable part of it is, therefore,  within the
periphery of the lower ribs above, and of the pelvis below.
It is completely separated from the cavity of the thorax by
the diaphragm, with the exception of the  foramina in the
latter, for transmitting  the aorta, the ascending cava, and
the oesophagus.  It is bounded below by the iliaci interni,
the psoas, and ths levatores ani muscles; on the front and
sides  by the five pairs  of muscles called  abdominal; and
behind by the lesser muscle of the diaphragm, the Quadrati
Lumborum, the lumbar vertebrae, and  the  sacrum.   The
figure of this cavity is, therefore, too irregular to admit of
a very rigid comparison with any of the common objects
of life; but a little  reflection,  on the course of its parietes,
will make it perfectly understood.  It should be borne in
mind  that the very great projection of the lumbar vertebra?,
forms for it a partial vertical septum behind; which, in thin
subjects, is almost  in contact with the linea alba in front,
and may be easily distinguished through the parietes of the
abdomen,  when the intestines are empty.
  Vol.  II—2 
6'
ORGANS OF DIGESTION1.
  The abdominal cavity varies only, inconsiderably, in its
vertical diameter, owing to the resistance of the diaphragm
above, and of the pelvis below;  neither does it change be-
hind, owing to the resistance of the spine, the ribs, and the
muscles there.  But as the introduction of food, the develop-
ment of gazeous substances during digestion, the evolution of
the foetus, and  many other  conditions, require some pro-
vision for its undergoing an easy augmentation of volume;
the latter  occurs principally forwards and laterally, by the
yielding of the muscles and by the extension of their apo-
neuroses.   The  diaphragm and the abdominal muscles, for
the most  part, act alternately; as  the former descends in
inspiration, the latter relax and  give  way to the contents
of the abdomen: but in expiration, the abdominal  muscles
contract, and the diaphragm is pushed upwards by the vis-
cera.   In attempts at the  expulsion of faeces, and in par-
turition, these muscles contracting and the diaphragm being
fixed all at the same  moment, the cavity of the abdomen
is actually much diminished.
  The viscera contained in the cavity of the abdomen are
of three kinds.  One kind is engaged in digestion and as-
similation; another in the secretion and excretion of urine;
and the third in generation.  As these viscera are numerous,
and it is of great importance to  determine with precision
their position and relative situation, anatomists are agreed
to divide the cavity of the abdomen into several arbitrary
regions.   This  js the more advantageous, as the  bony pro-
minences bounding the abdomen are  not sufficiently nume-
rous and  distinct, to afford  those points of departure and
of relation which they furnish in  other sections of the body.
To obtain these regions, consider  a line  or  plane as ex-
tended  across the  abdomen, about  two inches below the
umbilicus, from the superior part of the crista of one ilium
as it appears through  the  skin, to  the corresponding point
of the other  side.   Strike on  each  side a line perpendicu-
lar  to the preceding by commencing at the lower end of the
anterior inferior spinous process  of the ilium, and carrying 
OP THE ABDOMEN.
/
it up to the diaphragm.   Extend a fourth line across the
abdomen parallel with  the first, and intersecting the  two
last where they come upon the cartilages of the false ribs.
It is evident that these four lines or planes, two horizontal
and two vertical, will, with the assistance of the parietes
of the abdomen, furnish nine regions: three above; three in
the middle, and three below.   The central region above,
is the Epigastric; and on its sides are the right and the left
Hypochondriac.  The central  region in the middle,  sur-
rounding the navel, is the Umbilical; and on  its sides are
the right and the left Lumbar.   The central region below,
is the  Hypogastric; and on its sides are the right and the
left Iliac.   There are also  some subordinate divisions; for
example, the hollow in the epigastric region around the en-
siform cartilage, is  called the pit of the stomach, or Scro-
biculis Cordis; and  for an inch or two  around the sym-
physis pubis is the region of the pubes, (Regio Pubis.)
   Anatomists differ among themselves about the points of de-
parture and the position of the lines separating the regions.
Some fix them at arbitrary distances from the umbilicus, and
others assume the points of the skeleton.   The  umbilicus is
the most fallacious mark, because its elevation varies consi-
derably, according to the state of distention of the abdomen,
it being comparatively higher when the abdomen is tumid,
than when it is not.   Neither does it answer  to take the
anterior ends of the last ribs as the points for the upper hori-
zontal line to pass through; as they,  sometimes, are almost
as low down as the umbilicus itself.   The superior anterior
spinous processes are also objectionable as the points of de-
parture for the vertical lines: as they leave too  much room
for the central regions of the abdomen, and too little for the
lateral.  I  have, therefore, thought proper to substitute the
anterior inferior spinous processes.


   General Situation of the Viscera of the Abdomen.

   When the abdomen is so opened as to leave its viscera in
their natural position, they will  be found as follows: 
ORGANS OP DIGESTION.
   1. The Liver, the largest gland of the body, is in the
right upper part of the  abdomen, immediately below the
diaphragm.   It occupies  nearly the whole of the right hy-
pochondriac region; the upper half of the epigastric; and the
the right superior part of the left hypochondriac.  The an-
terior extremity of the gall bladder projects beyond its an-
terior margin.

   2. The Spleen is situated in the posterior part of the left
hypochondriac region.

   3. The Stomach, in a moderate condition of distention, oc-
cupies the lower half of the epigastric region, and the right
inferior portion of the left hypochondriac.

   4. The smaller  Intestine, when  moderately distended
by flatus, occupies  the umbilical  region, the  hypogastric,
portions of the iliac on each side, and also the upper part
of the cavity of the pelvis, when the viscera of the latter
are empty.

   5. The Large Intestine traverses the  cavity of the abdo-
men in  such manner as to perform almost the entire circuit
of it.   It begins in the right iliac region by receiving the
lower extremity of the  small  intestine, it then  ascends
through the  right  lumbar and the  right hypochondriac,
passes into the lower part of the epigastric or into the up-
per of the umbilical, according  to the state of distention  of
the stomach; thence it gets into the left  hypochondriac, be-
ing fixed higher up there than in the corresponding region
of the other side; afterwards it goes down into the left lumbar
and into the left iliac;  thence it passes into the pelvis, and,
descending in front of the sacrum, terminates in the orifice
called anus.

   6. The Caul or Omentum is a  membrane, of various densi-
ties, in  different individuals, and lies in front  of the intes-
tines.   Sometimes it is found spread over the latter like an 
OP THE ABDOMEN.
9
apron, but on other occasions is drawn up into the umbili-
cal region, forming a ridge across it.

  7.  The Pancreas lies transversely in the lower back part
of the epigastric region.   It extends from the left hypo-
chondriac region to the right side of the spine, and is placed
behind the stomach, so as to be covered by it.

  8. The Kidneys and the Capsular Renales, two in number
each, are placed in the posterior part of the lumbar region
on the side of the spine.

  9. The Urinary Bladder  and the  Rectum, in the male,
occupy the cavity of the pelvis, and  in the female between
them are placed the uterus,  the ovaries, and the vagina.

  As, in the dissection of the  abdominal  viscera, the sub-
ject- is  commonly placed on its back, so the  preceding
description is made out with a strict reference to that po-
sition.  Some  modification  in  the shape of the abdomen,
as well as in the situation of its contents occurs in standing
upright.  The front of the  abdomen  becomes more protu-
berant, the lumbar vertebrae make a  greater projection for-
wards.  The  pelvis  is so adjusted, in  order to bring the
acetabula directly in the  line of support to the spine, that
the  convexity of the sacrum  presents almost upwards,
and the superior straight looks forwards and  upwards  to-
wards the navel, so that  much  of the weight of the viscera
is thrown upon the pubes.  In this attitude most of the vis-
cera descend, but more obviously the liver from its weight,
size, and solidity.   Portal has verified this descent by com-
paring the thrusts of poignards into  the liver in the erect,
with  those  inflicted in  the horizontal position.   He also
asserts that the same may be ascertained in the living body
by applying the fingers  under the false ribs, and  then di-
recting the  person to change from the recumbent into the
vertical position.  The spleen affords the same results when
it is slightly enlarged, and the descent of the liver and spleen
will of course ensure that of  the stomach and intestines. Ac- 
10
ORGANS OP DIGESTION.
 cording to Winslow, the pain and faintness which are felt
 after long abstinence, come from the vacuity of the sto-
 mach and intestines, which thereby withdraw their support
 from the liver, and permit it to drag upon the diaphragm.
   The presence of flatus in the stomach and intestinal canal,
 seems to be entirely natural to them; for it is comparatively
 rare to  find them destitute of it, even when  they contain
 no food or faeces.   The large intestine is, however, more
 frequently found contracted or empty than the small.  Owing
 to the flexible character of a considerable portion of the ab-
 dominal parietes, the latter by their own contraction as well
 as by atmospheric pressure,  are kept in close  contact  with
 the viscera, and the viscera again, by the same influence,
 are kept in close contact with one another; so that notwith-
 standing the irregularity of their forms and  the fluctuating
 size of the hollow ones, there is no unoccupied space in the
 cavity of the belly.
   Several instances are reported by anatomists, in which a
total transposition of the abdominal viscera has occurred, so
that those which belonged to the right  side were placed in
the left*   They are, however, exceedingly rare; in proba-
bly more than fifteen hundred  observations, I have never
met with one of the kind.
                    CHAPTER  II.

     OF THE PERITONEUM AND SEROUS MEMBRANES
                      GENERALLY.

             SECT. I.—OP THE  PERITONEUM.

  The sides of the abdomen are lined, and  its  viscera are
covered by a membrane called Peritoneum.  As the reflec-
tions of this membrane, by being thrown over the periphery
of almost every viscus of the abdomen, consequently assume
* Portal, Haller, Sandifort, &c. 
OF THE PERITONEUM.
11
the same shape; and as it lines, without  exception, the in-
terior surface of every part of the abdomen, its form is ex-
tremely complicated, and can only be judged of accurately
after the study of the viscera is completed.  For the pre-
sent it will only be necessary to give the outline of it, leav-
ing the details to each appropriate occasion.
  In man,  it is a complete  sac, having no hole in it; but
in woman,  its cavity communicates externally through the
fallopian tubes.   It has  a  double use: In consequence of
covering the viscera, it is so reflected from them to the sides
of the abdomen, that its processes keep the viscera in their
proper places, and therefore answer as ligaments: again, its
internal surface being smooth, indeed highly polished, and
continually lubricated by a thin, albuminous fluid, corres-
ponding with the synovial  membrane of the joints, the mo-
tions which the viscera have upon  each other in exercise,
and in the  peristaltic movements of the bowels, are much
facilitated.
  The manner in which a double night-cap is applied to
the head, will afford the easiest conception of the reflections
of the peritoneum.  If there  were only one viscus in the
belly, and  that of a somewhat regular outline, as the spleen,
the comparison would be rigid, and perfectly appreciable.
One part of the cap is close to the head, and compares with
the peritoneal coat of the spleen; the other is loose, and is
equivalent  to the peritoneum, where it is in contact with the
parietes of the belly.  It  is also evident from this,  that
none of the viscera can be said to be  within the cavity of
the peritoneum; that they are  all on its  outside; and that
a viscus, in  getting a coat from the  peritoneum, merely
makes a protrusion into its cavity.  Starting with this sim-
ple proposition, it is easy  to conceive of a  second, a third
body, and  so on, deriving  an  external coat from a protru-
sion into the same sac. Admitting these bodies to be spheres,
the  proposition is immediately intelligible; and, as a last
step from it, the idea is not rendered much more complex
by substituting  any bodies,  even the most irregular in form,
for these spheres.   Such,  then, is the fact in regard to the 
12
ORGANS OF DIGESTION"
stomach,  intestines, &c.; they all, with exceptions  to be
stated, derive an external coat from the peritoneum.

   The  Peritoneum  is for  the most part smoothly spread
upon the interior surface of the abdominal muscles.   It ad-
heres to them with considerable firmness by means  of in-
tervening cellular substance:  this adhesion, where it closes
the posterior opening of the umbilicus, is unusually strong.
Below, the uniformity of the  membrane as it descends from
the navel  to the pelvis is interrupted by its being reflected
over the urachus, and over the remains of the umbilical ar-
tery on either side.  Where  the urachus is, it forms  an ob-
long prominent ridge reaching to the upper extremity of
the bladder;  and, as regards  each umbilical artery, the du-
plicature is of variable breadths in different individuals; but
always  forms a well  marked falciform  process, reaching
from near the umbilicus to the lower  side of the bladder,
and dividing the  inguinal  region  into two parts or  fossae,
one next to  the pubes, and the other  nearer to  the  ilium.
In the  undistended  state of the bladder  the peritoneum
reaches to the pubes, is reflected from the latter to the up-
per, and then goes over the posterior surface of  the blad-
der.   In the male it goes from the posterior lower end of
the bladder to the rectum, but in the female it does not
descend so low there, and passes  from the bladder to the
vagina and uterus, and afterwards to the rectum.
  In the concavity of the ilium, and in the lumbar regions,
the peritoneum is attached by long loose cellular substance,
which permits it  to be stripped off easily, simply by tear-
ing.   In these several regions it encounters the colon, over
which it is  reflected, and  thereby forms the  Mesocolon;
thence it passes in front of  the kidneys, but separated from
them by a thick layer of cellular  and adipose  matter,  and
immediately afterwards it is thrown into a long duplicature,
extending obliquely across the lumbar vertebrae from  above
downwards,  and  to  the right side.   This duplicature in-
cludes the small intestines,  and is the Mesentery.
  In the highest regions of the abdomen, the peritoneum is
in the greater part of its extent  uniformly reflected over 
ANATOMY OF SEROUS MEMBRANES.
13
the concave surface of the diaphragm, and adheres so close-
ly to it, as to require a cautious and protracted dissection for
its entire removal.   As the remains of the umbilical vein
of the foetus are still found, but in a ligamentous condition,
going from the navel to the under surface of the liver, their
existence  gives rise to a broad falciform duplicature of  pe-
ritoneum, which passes from the upper half of the lineaalba
and  from  the middle line of the diaphragm  to  the liver.
Another line of attachment, or of reflection, of this mem-
brane to the liver, is found all along the  posterior margin
of the latter.   In the same region it  is also reflected from
the diaphragm to the spleen and to the stomach.   Such is
the general account of the course of the peritoneum.  Each
of the duplications has a distinct name, and some peculiari-
ty of organization or of relation, which will require a spe-
cific description and a frequent allusion to it.
  It is proved, from what has been  said, that the perito-
neum is a single and a complete sac,  and that with the  ex-
ception stated of  the fallopian tubes, there is  no hole in it
either for  the passing of blood vessels, nerves, or viscera.
And that it is so folded over the abdominal  viscera, that with
patience and sufficient address, one might remove it from
their surface and extract them, without oven laying open its
cavity:  an experiment said  to have  been successfully ac-
complished by Nicholas Massa* and some  other anatomists.

SECT. II.--GENERAL ANATOMY OP THE SEROUS MEMBRANES.

  As the peritoneum presents one of the best examples of a
numerous class of membranes,  called Serous,  it  will he
useful at this point to inquire  into their general  condition
and  properties.   They are,  for the  most  part  thin,  and
strongly resemble compressed cellular membrane, having
been, indeed, by some anatomists considered as such. They
invariably assume the form of perfect sacs, and as they  are

           *  Annot. Liber. Introduct. an. 1539. Portal.
  Vol. II.— 3 
14
ORGANS OF DIGESTION.
found in all parts of the body, they are kept distinct from
each other.   The arachnoid membrane of the brain, the pe-
ricardium, the pleura, the synovial membranes of the joints,
the bursae mucosae of tendons, the peritoneum,  and the
tunica vaginalis testis, belong to this  class.   They are not
all of the same thickness,  as some are much more dense
than others; they adhere to neighbouring parts by a lamina
of cellular substance, which is also of variable thickness and
ductility; indeed, on  some occasions,  it is not entirely dis-
tinct, from its extreme shortness and tenuity.
  As the serous membranes are  only displayed  over the
surface  of the organs which they cover, after the manner of
a double night cap drawn over the head; their cavity always
remains,  notwithstanding  it is variously modified by the
shape of the organs protruded  into it; and  has its parietes
in contact, owing  to  external  compression.   They are en-
tirely distinct from the intimate or peculiar structure of the
organs covered, and are displayed over those of the most
dissimilar functions, as, for example, the intestines and the
liver.   A sac of this description,  then, is of infinite impor-
tance in establishing between organs which border upon one
another, a strong demarcation: and consequently in warding
off any injurious influence which their  dissimilar natures,
would otherwise cause them to have upon each other.  Im-
portant organs are, therefore, invariably thus insulated,  s6
that whether  in a healthy or  in a  diseased  state, their
actions are carried on within themselves; and not only so,
but it is even possible, and indeed is found  in morbid dis-
sections, every day; that an organ may be diseased while  its
serous  covering is unaffected; or the reverse.    Thus we
have large suppurations in the liver, while its peritoneal
coat is healthy; large accumulations of water in the tunica
vaginalis testis, while the testicle itself is sound; in the tho-
rax, with sound lungs and  heart;  in the abdomen, with vis-
.cera generally  sound; in the joints, without an affection of
the  bones.   Nothing is more  common  than to see partial
 adhesions, the result of inflammation, causing the opposite
sides of these sacs to  adhere, without any evident constitu- 
ANATOMY OF SEROUS MEMBRANES.
15
tional  or  visceral derangement; and some of our plans of
cure, as in the hydrocele, are founded upon this  well es-
tablished fact.
  The serous membranes are throughout thin, transparent,
and white: in some points  their tenuity is so extreme that
they seem to consist simply in a smooth, polished surface,
spread over parts; this is strikingly the case on the interior
face of the dura mater, on  the ventricles of the brain, and
on the cartilages of the joints.   The evidence of their ex-
tension there, is consequently derived principally from in-
duction;  and from morbid alteration, in which they become
thickened.  Their internal surface, in a natural state, is al-
ways smooth, highly polished, shining; and being also lu-
bricated by its peculiar unctuous secretion, the opposite pa-
rietes, when they come into contact, glide freely upon each
other; a circumstance indispensable to the free action of the
joints, and to the peristaltic motion of the bowels. Bordeu
has asserted, that these remarkable characters of the serous
membranes, depend upon the compression and the friction
to which they are continually exposed: but  to this opinion
the argument of Bichat is  unanswerable,  that in their ear-
liest observable period in the foetus, they have the same po-
lish.
  The fluid secreted from the serous membranes resembles,
strongly, the serosity of the blood.  It is poured out conti-
nually by the exhalent orifices, and in a short time after-
wards is taken up by the absorbents, so that in a nafural state
there is seldom more than sufficient to lubricate the surfaces
of the membrane. When the abdomen of an animal recent-
ly killed is exposed to the air, this fluid rises in the form of
a vapour.  The several experiments,  as the application of
heat, mineral acids, and so on, which prove the abundance
of albumen in the serum of the blood, produce the same re-
sults when applied to the secretion from  the serous mem-
branes.
  The system of serous membranes has been considered by
Bichat and others as only a modification of cellular mem-
brane, for the following reasons   The inflation of ajr into 
lti
ORGANS OF DIGESTION.
 the cellular tissue subjacent to them, reduces them to the
 form of cellular substance.  Protracted maceration produces
 the same effects with more certainty and precision.   When
 cellular membrane is inflated, the parietes of the distended
 cells resemble strongly the finest parts of the serous system,
 as the arachnoid membrane.   There is an identity of func-
 tions and of affections, for they are both continually engaged
 in the great work of exhalation and absorption,  and suffer
 in the same way from  dropsical effusion, with the only dif-
 ference that the latter  is more amassed in the one than in
 the other.   My own experience goes to prove, that dropsy
 very seldom manifests itself,  to any extent, in the cellular
 tissue without also going to the serous cavities, and the re-
 verse.   The serous  membranes are also of a  uniform tex-
 ture, like cellular substance, and present no appearance of
 fibres.
  The serous membranes are furnished  with a great abun-
 dance of exhalent pores, and of absorbents, which carry on
 their functions  with  great activity.   They receive only the
 colourless part of the blood, whence the  uniform transpa-
rency of these membranes.   In order to establish the exist-
 ence of exhalent pores, by strangulating a  piece of intestine
 with a ligature  for thirty-six or forty-eight hours, they be-
 come evident, by dilating themselves so as  to receive red
 blood.   A fine coloured injection  produces the same  result;
 and also moistens, by the escape of its watery particles, the
 surface of the intestine, by a very fine halitus or dew.  The
 intestine of a living  animal, if wiped perfectly dry, will,
 after the same  way,  soon present another coat of serosity
 on its surface.   The existence of absorbents lo a great ex-
 tent in them, may also  be equally  well proved,  as they very
 readily  receive a mercurial  injection, which diffuses itself
 over their whole surface, and  causes them to have the ap-
 pearance of being formed entirely of such vessels.    The
 readiness with which fluid effused  into their cavities is taken
 up, is another proof  of the same.    Bichat once saw them
 distended with  air in a man who  had become emphysema-
 tous from poisoning.   Mascagni has frequently found them 
ANATOMY OF SEROUS MEMBRANES.
17
distended with the fluid of dropsical collections, which he
recognised by its colour.   It happened to the same anato-
mist to find in two bodies, where there had been an effusion
of blood into  the thorax, the absorbents of the lungs gorged
with blood.   This faculty of absorption may sometimes be
proved to continue for some hours after death, by keeping
an animal in  a warm bath.   Mascagni asserts, that he has
witnessed its continuance for fifteen, thirty,  and even for
forty-eight hours; it is not improbable, however, that there
was some illusion in these instances.
  It is more than probable that the serous  membranes are
entirely deprived of red blood vessels;  the latter unques-
tionably exist, in great  numbers, on the exterior surface,
where they creep through the cellular substance, but they
may be removed with a scalpel without affecting the conti-
nuity of these membranes.   Again, where  these mem-
branes are free and  unconnected on both surfaces, as in
some parts of the tunica arachnoidea, there is no appearance
of red blood  vessels.  In hernial protrusions, where there
is a considerable prolapse  of peritoneum, the blood vessels
which are found abundantly about the neck of the sac, do
not follow the course of the protrusion.   Unquestionably
some communication exists between the arterial system and
the serous membranes, as proved by exhalation and morbid
phenomena, but the mode is not well ascertained.
  In common hernia and in dropsy,  the serous membranes
become more thick: from my dissections I am inclined to
think, that this change is not so great as is generally allowed;
for most frequently, by a careful removal  of the exterior
cellular substance, they have  been restored to their primi-
tive condition.  In other cases, as in large umbilical hernia?,
they are so much attenuated as to be found with difficulty.
  The power of extension which these membranes possess,
is strikingly marked in dropsical effusions,  in  the develop-
ment of tumours, and in pregnancy; but much of this ap-
parent quality is derived from their mode of attachment to
adjacent  parts, whereby they are drawn  from one surface
to cover another.   This happens daily where the perito- 
18
ORGANS OF DIGESTION.
neum is drawn from the lower part of the abdomen to co-
ver the bladder in the distentions of the latter; in pregnancy,
where it is drawn  upon the growing uterus  from all the
neighbouring parts; and in the distentions of the stomach
by food or flatus, where  it is drawn up from the omenta.
The serous membranes  have also a power of contraction
equal to that of their extension;  but it should not be con-
founded with that condition where they are simply restored
by the connecting cellular substance, to the surfaces where
they originally belonged.
  The sensibility of the serous membranes, from the want
of nerves in them, is extremely obscure in a natural state,
and only affords an imperfect sensation of touch.   This is
proved by the impunity with which they may be irritated
on living animals.  But, when the condition of inflammation
is once established, they feel the most acute and distressing
pain.   Though they resist most frequently, and for a  long
time, disease in adjacent parts, yet it not unfrequently is ex-
tended to them at last.   In such cases it is generally a local
instead of a universal affection, which  is communicated to
them: Thus, in the cancer and scirrhus of the uterus; in
disease of the spleen, and so  on; the portion of peritoneum
nearest the affected organ, manifests the marks of the disease
by preternatural adhesions and by disorganization, without
the whole membrane being involved.
  As the serous system  consists  in many species of sacs,
so each of them has some  peculiarity of organization, of
attachment, and  of vital  properties, which  are stated else-
where in the account of the species themselves.


              SECT. III.--OP THE OMENTA.

  There  are four  processes  of the peritoneum,  each of
which  is designated under the term Omentum, Epiploon,
or Caul.

  1. The Omentum Minus or the Hepatico-Gastricum, ex-
tends, as its name imports, between the liver and the sto- 
THE OMENTA.
19
mach.   It begins at the transverse fissure of the liver, and
proceeds from it, from the right side of the lobulus spigelii,
the front of which it conceals, and from the inferior poste-
rior face of the tendinous centre of the diaphragm; it is at-
tached to the lesser curvature of the stomach in all the space
between the cardiac and the pyloric orifices.  Its right mar-
gin reaches beyond the pylorus to the duodenum, and in-
cludes the vessels going to the liver, and the biliary ducts;
in consequence of which, this margin is called the Capsule
of Glisson.
   The two laminae  which compose it are thin and transpa-
rent,  and have but little fat in them; in approaching the sto-
mach they become  very distinct  from each other, and re-
ceive between them the superior coronary vessels of the
stomach.  One lamina then goes before the stomach and the
other behind, in the form of a peritoneal covering. These
laminae having covered,  in that way, the  anterior and the
posterior surface of the stomach,  unite again on the greater
curvature of the latter, to form the beginning of the omen-
tum majus.

   2.  The  Omentum Majus or Gastro-Colicum, as indica-
ted by its name, is connected at one end all along the greater
 curvature of the stomach, and by the other along the trans-
 verse part of the colon.   As it commences by two laminae,
 so it is continued throughout in the same way.   It is com-
 monly  found more or less spread on the front surface of the
 small intestines, but occasionally it is tucked up in the epi-
 gastric region.  When fairly spread out either naturally or
 artificially, its course will be found as follows: It first of  all
 descends from the  stomach to the pelvis; it then turns up-
 wards so as to reverse its course, and continues to ascend
 till it reaches the colon.   Its two laminae then  separate and
 receive the colon between them, so that, in this respect, the
 arrangement is entirely conformable to what happens to the
 stomach.   The subsequent continuation of these laminae is
 the mesocolon, which will be more particularly described.
    As the omentum majus consists  of two laminae in  its
 whole  extent, it is clear  that it  resembles a  flattened bag 
20
ORGANS OF DIGESTION.
 lined by another bag,  so that in its whole thickness, when
 held between the fingers, there are four laminae.   It is an
 irregular quadrilateral  membrane, which in corpulent sub-
jects, is interspersed with a great deal of fat; but, in such
 as are emaciated, it is wholly destitute of the latter; and in-
 stead of being entire in its parietes, is a delicate reticulated
 membrane, so that the rule about the integrity of the peri-
 toneum is not fully accurate as applied to this section of it.
 On the  right side it is continuous with the omentum coli-
 cum, and on the left with the omentum gastro-splenicum.

   3.  The Omentum Colicum may be considered as a con-
tinuation of the omentum majus along the ascending and a
part of the transverse colon.  In  some rare cases, (for in
my own observations I have not met with the arrangement,)
its origin is continued downwards to the coecum, and at its
left margin is extended along the transverse  colon to the
spleen.   Much more  commonly it  is, as stated, simply
an appendage of the great omentum, or its right flank, ad-
vancing for a short distance along the ascending colon.
  It consists of but two laminae in all, commonly contain-
ing fat, but in this respect subject to  the  same rule as the
omentum majus.

  4. The Omentum Gastro-Splenicum is the  left flank or
margin of the omentum majus, extended from the great end
of the stomach to the spleen.  It of course consists of  but
two laminae, which contain between them the splenic vessels
and the vasa brevia.

  By looking for the posterior end of the gall bladder, and
then passing a finger under the right margin of the hepati-
cogastric omentum,  or, in other words, under the capsule
of Glisson, where it passes from the liver to the duodenum;
the finger will be found to have  insinuated itself behind the
stomach, and, by being directed downwards, will be thrust
into the sac or cavity of the  great omentum.  In children,
where the latter is less reticulated than in adults, and con-
sequently more entire, a large blow-pipe introduced at the 
OF THE OMENTA.
21
 same point will enable  one to inflate this cavity, and to se-
 parate its anterior from its posterior wall.   This aperture,
 called the foramen of Winslow, is precisely the means by
 which the internal or lining  lamina of the omentum majus
 is introduced, so as to make this process of peritoneum
 double throughout its whole  parietes.  Though this fact of
 duplicity is generally  conceded, no author heretofore, to
 my knowledge, has pointed out satisfactorily the means;
 and for the suggestion  of it, I am indebted  to a learned and
 zealous member of the profession, Dr.  Hugh Hodge of this
 city.   Struck, at an early period of his studies,  with the
 difficulty of tracing a double  sac to the omentum majus, out
 of a single membrane of the peritoneum, this suggestion
 was happily made by him,  to remove the difficulties of other
 explanations.   An  attempt at a diagram  formed upon any
 other principle I have  invariably seen to fail.  If the reader
 has conceived the idea, the inference will be plain, that the
 lining lamina of the omentum majus is continued as a com-
 mon peritoneal covering over the posterior face of the sto-
 mach, and then forms the posterior lamina  of the hepatico-
 gastric omentum. It will also be plain that the same lamina,
 having reached the colon in its return, continues afterwards
 as the upper lamina of the  transverse mesocolon.

  From what has been said concerning the general qualities
 of the peritoneum, it is to  be understood that though it en-
joys much power of gradual extension: nevertheless this
 quality is not sufficient to  enable it to endure, without a
 special provision; the  sudden and extensive dilatations to
 which the stomach and bowels are exposed, from the intro-
 duction  of food and from the' evolution of gases during di-
 gestion.   Of all the coats of these organs, it is the least ex-
 tensible and contractile; its rupture, therefore,  is guarded
against by one invariable rule.   For example: as the mus-
cular and other coats of the stomach dilate,  the peritoneum
is drawn from the omentum minus  and majus to cover the
stomach; therefore, as the stomach enlarges, the omenta di-
minish;  and as the stomach  decreases, the omenta,  by the
restoration of peritoneum,  resume their primitive size.  In
  Vol.  II.—4 
22
ORGANS OF DIGESTION.
this way the uterus, notwithstanding its great augmentation
in the progress of pregnancy, still  keeps itself covered by
peritoneum, from the ability of the  latter, as mentioned, to
slide  from one part and to  apply itself to another.  The
true intention, then, of the apparently useless length of
many processes of the peritoneum, is explained,  by their
being a provision  for the augmentation of the hollow vis-
cera of the abdomen,  in the  discharge of their natural func-
tions.   Adopting this explanation as the basis of our obser-
vations, we shall find that according to the probable or even
possible augmentation of a viscus,  so  are its peritoneal at-
tachments.  The stomach, which next to the uterus enlarges
more than any other viscus, gets its  subsidiary supply of
peritoneum from the length  of the omentum minus and ma-
jus; the colon, which is next in order, is supplied from  the
length of  its  mesocolon; the small intestines,  which  are
next, from the length of the mesentery.   The latter, how-
ever, would be too long for  that simple purpose; but the ob-
jection is removed, by  recollecting that the mesentery  has
also to  accommodate numerous  chains  of  lacteal glands,
through which the chyle must pass in its elaboration, before
it is fit to  enter into the general circulation.   The liver,
being of a size almost stationary, has its peritoneal attach-
ments proportionally short; and its peritoneal covering,
from the shortness of the connecting cellular substance, is
disqualified from sliding.  The  spleen  is in the same pre-
dicament with the liver, except that  its size is not station-
ary; but, in this case, the peritoneum presents a phenome-
non entirely remarkable: it  wrinkles upon the contraction
of the spleen.
  If this mode of reasoning, derived from an arrangement
of parts which no one  denies,  be correct; it follows that
physiologists have erred sadly in the  supposed uses of  the
omentum majus.   That this organ is, in fact,  only subsi-
diary to the enlargement of  the stomach and colon, so as
to prevent the rupture of their  peritoneal coat, and  that it
is neither intended to keep the  belly warm, as so learned a
naturalist as M. G. Cuvier  has suggested;*  nor is it a spe-
                  * XXII. Lecon D'Anat. Comp. 
OF THE OMENTA.
23
cial store-house for the wants of the system during the des-
titution of other aliment, further than adipose matter in
other parts of the body is.*  In regard to the first theory,
it does not appear that the inhabitants of cold climates are
better furnished with an omentum majus than those of the
torrid zone: that it is better developed in winter than it  is
in summer; that it is tucked up in warm weather to cool the
intestines, or spread out in cold weather to make them more
comfortable.   On the contrary, it is ascertained that its po-
sition is variable at all seasons; that in the coldest of weather
it is as often found  collected in the  epigastric region,  or  to
one  side of the abdomen, as  it is  in the  warmest;  conse-
quently its position is the result of whatever motions may,
for the time, have been impressed upon it by the distention
of the stomach,  and by the peristaltic movements  of the
bowels.   In regard to the theory of Dr. Rush, the objec-
tion is insurmountable, that  children, who are equally, if
not  more, exposed  to starvation  and  sickness  than adults;
never have fat,  except in very small  quantities,  in the
omentum, and  that  only along  the  course of its vessels.
The fat is, therefore, not to be viewed  as an  essential cir-
cumstance in the structure of the omentum, as all children
and many adults have it only very sparingly: for the omentum
being wanted as a membrane of reserve to the stomach and
colon, the deposite of fat in it is in obedience to one of the
general laws of the system, whereby the cellular substance
beneath  the serous membranes is disposed to secrete fat as
the  individual advances in life; which is exemplified on the
heart and in the pleura.  Another argument is, that in the
ruminating  animals,  where' there  are  four stomachs, and
from the vegetable nature of their aliment these  stomachs
must, in the  course of digestion, be very much distended,
the  great omentum is of proportionate magnitude.!
   As in other parts of the body the fat of the omentem accu-
mulates in animals that take little exercise, while it is very
deficient in such as lead an active life.

  * An inquiry into the uses of the omentum, by James Rush, Philad. 1809.
  ■f Cuvier, XXII. Lccon, loc. cit. 
24
ORGANS OF DIGESTION.
  I am induced to believe that the hard knots felt in the ab-
domen of such persons  as suffer from abdominal affections,
frequently depend upon the accumulations of the omentum
majus, at particular but variable points.
                   CHAPTER III.

            OF THE CHYLOPOIETIC VISCERA.

              SECT. I.--OP THE STOMACH.

  The Stomach (Ventriculus Stomachus) is a hollow vis-
cus, situated in the epigastric region, intended to receive at
one end  alimentary  matters from  the  oesophagus, and to
transmit them, at its other extremity, after digestion, into
the intestinal tube.   It is a sort of conoidal sac, curved con-
siderably upwards, and presents two Faces, two Orifices, two
Curvatures, and two Extremities.
  The Faces of the stomach are, from their position named
anterior and posterior, or, one presents to the spine and the
other towards the linea alba. The flat configuration is rendered
more obvious when the organ is empty; for when distended
it is rounded, and the anterior face is caused to look forwards
and upwards from the resistance of the spine behind.  In other
respects they do not present any thing worthy of particular
attention.
  The two Orifices of the stomach are named Cardia and Py-
lorus.  The first is at the left and most superior part, but re-
moved to the distance of two inches or more from the left
extremity.  It is generally considered a smooth uninterrupted
continuation of the oesophagus into the stomach, immediately
after the  oesophagus has passed through  the diaphragm into
the abdomen.  But in a preparation by me, Dec. 1828, made
by drying, and now in the cabinet of the anatomical chair, a 
OP THE  STOMACH.                 25
circular rounded pad is very perceptible at the cardiac ori-
fice; being elevated two lines or more all around, so that it
makes a perfect ring  of from eight to  twelve lines broad at
its base.  This pad seems to be formed of a substance sui
generis, which is almost perfectly white,  elastic, and con-
sists of the finest filaments resembling carded cotton: it is
placed between the lining membrane of the cardiac orifice
and the adjoining coat.   The pylorus, when viewed  exter-
nally, seems like a smooth continuation of the stomach into
the duodenum; but when felt, there is a manifest thickening
of the part, depending upon a structure to be presently ex-
plained.  It points upwards and to the left side, but is,  by
the  whole  thickness of the liver, lower  down than the
cardia.
   The  two Curvatures are designated the great and  small,
or the upper and the lower.  The  first, forming the upper
margin of the stomach, is  bounded  at its  extremities by
the orifices, and is very concave; its curvature is maintained
both by a natural configuration and by the small  omentum.
The great curvature forms the whole inferior periphery of
the  organ, extending  also from  one  orifice to the  other.
When the stomach is flattened, these curvatures form very
evident boundaries to the anterior and the posterior faces.
   The Extremities of this  organ are singularly dispropor-
tionate in  size.   That  on the left forms the base  of the
cone, or the large extremity, and projects considerably  be-
yond the cardia towards the spleen.   It is a rounded cul-
de-sac,  or  tuberosity,  the  dimensions of  which will of
course  vary according to  the state  of distention.  The
right extremity, on the contrary, is produced by a gradual
diminution of the organ from its middle to the duodenum.
When  the stomach  has approached within an inch or two
of the latter,  it  suffers a  sort of  constriction, which gives
to  the  right end a more cylindrical  shape.  This part is
sometimes called the little cul-de-sac, or the antrum pylori.
   Where the  stomach has been kept  empty for  some time
previous to death, it is found not much larger than  an in-
testine; its variable  magnitude,   therefore, prevents any
very rigid  rule of dimension from being applied to it; most 
26
ORGANS OP DIGESTION.
 commonly, however, we find it between the capaciousness
 of a pint and a quart measure.
   It is  retained in its situation by its continuity with  the
 oesophagus and duodenum; also by the hepatico-gastric, and
 the gastro-splenic omentum.   It is in contact above, at its
 lesser curvature, with the  diaphragm, the  left lobe of  the
 liver, and  the lobulus spigelii; at its great extremity with
 the spleen, at its posterior face with the pancreas, and at its
 greater  curvature with the colon and the mesocolon.

   The stomach is formed by four laminae of a character es-
 sentially differing from each other: The  Peritoneal,  the
 Muscular,  the Nervous, and the Mucous.
   The Peritoneal Coat envelopes the stomach completely,
 and adheres closely except at the curvatures, where, as has
 been mentioned, a provision is made for the distention of the
 organ, by the  looseness and the separability of the attach-
 ment of the two laminae of the omentum minus and majus.
 An uncovered space  will consequently be found  between
 the laminae at these places, along which the vessels run that
 furnish the stomach.   The peritoneal coat is very thin, and
 is attached to the subjacent muscular, by  very fine cellu-
 lar substance, which permits it to be raised from the mus-
 cular by a  careful dissection.
  The Muscular Coat is intermediate in thickness to that
 of the intestines and of the oesophagus, but  its fibres are
pale, are collected into flattened  fasciculi,  and go in three
 directions.   The most superficial are a continuation of  the
longitudinal fibres of the  oesophagus, are  less  numerous,
and  less uniform in  their  distribution,  than the  circular
fibres.   The greater  part of them forms a flattened broad
fasciculus, which extends along the  lesser curvature of the
stomach, from the cardiac to the pyloric orifice.   A thinner
and  less distinct fasciculus may be traced over the great
cul-de-sac,  and,  somewhat indistinctly,  along the greater
curvature,  and a few others may be seen on the anterior
and posterior faces of the stomach.  The second series con-
sists in  a lamina of circular fibres distinctly covering the
whole surface of the organ.  They are  not so numerous 
OP THE STOMACH.
27
 near the cardia, but become more abundant as they are exa-
 mined towards the pylorus, in the  vicinity of  which they
 are multiplied so as to form a lamina of two lines or more
 in thickness.  They are parallel with each other, and, when
 the stomach is much distended, their fasciculi separate so as
 to leave interstices between them in many places.   The in-
 dividual fibres do not surround entirely the stomach, but are
 rather segments of circles.  The third and deepest series of
 fibres may be called oblique, and are arranged into two broad
 flattened fasciculi, one of which is placed to the left side of the
 cardia, and is prolonged over the anterior and the posterior
 faces of the stomach;  while the  other, being  to the right
 of the same  orifice, is  extended over the anterior  and the
 posterior  faces of the cul-de-sac, where it supplies the want
 of transverse or circular fibres; they are considered as a con-
 tinuation  of the circular fibres of the oesophagus.
  The Nervous Coat  connects  the  muscular with the mu-
 cous.   It is formed from a compact, thick, and short cellu-
 lar substance, which contributes much to the general strength
 of the organ, and serves to conduct the blood  vessels and
 the nerves to the mucous coat.
  The Mucous or Villous Coat is the most  internal, is not
 quite a line  in  thickness, and can  be readily raised up by
 dissection.   In an undistended state of the stomach it is
 brought into a number of wrinkles, which are very irregu-
 lar in their form, size,  and direction, and disappear imme-
 diately on inflation, or at least  leave but very faint traces.
 It is continuous  with the internal membrane of the oesopha-
 gus and of the  duodenum, but presents a surface differing
 from either of them, and  which is  rendered very apparent
 by floating it in water.   The epidermis, which is continued
 along the  internal face  of the oesophagus, ceases around the
 cardiac orifice, and, by a slight maceration, may be raised
up and demonstrated to terminate there.
  This membrane or coat, the office of which is to secrete
the gastric juice for the digestion of articles of food, presents
 a surface that resembles very much common velvet, from
 whence the term villous was applied to it.  It is very com- 
28
ORGANS OP DIGESTION.
mon to find it, if examined a short time after death, present-
ing, particularly along the smaller curvature and at the great
end, a pink and sometimes a deeper colour, produced by an
accumulation of blood in its veins during the agonies of dis-
solution, and probably caused in the first instance by an ar-
rest of the pulmonary circulation.
   The texture of this  membrane is soft, loose, and  easily
lacerated.  When floated in  water and examined with a
magnifying glass, it is found  to  have  a superficial honey-
comb arrangement, and to be studded with a multitude of
small mucous orifices not more than the fiftieth part of a
line in diameter.   In the vicinity of the cardiac and of the
pyloric orifices, the same arrangement is more obvious and
conducts to some small muciparous glands, which are more
or less apparent, and called the glands of Brunner.
   At the junction of the  lesser  extremity of the stomach
with the duodenum,  the internal membrane is thrown into
a circular duplicature  constituting the pyloric valve, and
abridging the size of the orifice.  It is seen most favoura-
bly, in the distended  and  dried state,  and  then presents a
sort of septum  not unlike the form of the iris.   Around
the external  periphery of this ring, the circular  muscular
fibres have a sudden augmentation of numbers, which gives
them, when viewed from the duodenum, the appearance of
a distinct circular muscle, occasionally called the muscle of
the pylorus, but it does not exist in a  state so separate  as
this name indicates.   The opening of the  valve is general-
ly circular, but sometimes ovoidal, and it  is sometimes  to
one side.

   It is very common to find the stomach divided as it were
into two compartments, by a contraction of its middle, re-
sembling that of an hour glass.  It is  said that this occurs
habitually during digestion; in my personal observations,
however, I have seen the stomach  more frequently in this
state when it contained nothing, not  even air, than  when
articles of aliment were in it.

  The stomach is extremely vascular.  Its arteries,  being 
INTESTINAL CANAL.
29
branches of the Caeliac, are the  Gastric, the Right, and the
Left Gastro-Epiploic, and the Vasa Brevia.  The first goes
along its lesser curvature, the second and the third along its
greater curvature, and the last,  from four to six in number,
go to its cul-de-sac.   They all  approach it between the la-
minae of its omenta, and undergo many divisions and sub-
divisions in the  cellular coat; they at length terminate by
forming a very fine  and delicate vascular arrangement in
the substance of the mucous membrane, and by  being suc-
cessfully injected give to the latter a thorough tinge of red.
The veins follow the course of the arteries, and like them
have frequent anastomoses, but are larger; they terminate
either directly  or  indirectly  in the  trunk of  the Vena
Portarum.   The nerves of the  stomach come from the Par
Vagum, and  from the semilunar ganglion of the Sympa-
thetic.   Its lymphatics arise from both the external, and
the internal surfaces, and their trunks having to pass first
of all to the lymphatic glands, situated along the curvatures,
afterwards empty into the thoracic  duct.


         SECT.  II.--OP THE  INTESTINAL CANAL.

   The Intestinal Canal is from  thirty to thirty-five feet in
length, and extends from the pylorus to the  anus.   Owing
principally to a well marked  difference in magnitude, it is
divided by anatomists into the small  and into the Large In-
testine.

                Of the Small Intestine.

   The Small Intestine (Intestinum Tenue) commences at
the pylorus; and terminates in  the right iliac region by a
lateral aperture into  the large intestine.  It is four-fifths of
the length of the whole canal,  and consequently measures
from twenty-four to twenty-eight feet.  When moderately
distended its  diameter is about one inch.   It retains from
one end  to the  other an  uninterrupted cylindrical shape,
with the exception  that if the two ends be  compared, the
   Vol. II—5 
30              ORGANS OP DIGESTION.
upper will be found larger than what is stated as the medi-
um measurement, and the lower smaller; or, in other words,
as the intestine decreases  successively from above down-
wards, it as a whole is slightly conoidal, though this dimi-
nution is so gradual that it is not perceptible at any given
point.
  The Small Intestine, like the stomach, consists of four
distinct coats, the peritoneal, the muscular, the cellular, and
the mucous.
  The Peritoneal Coat is complete, and forms the external
surface.  It is continued afterwards in two laminae from the
intestine to the lumbar vertebrae, thereby constituting the
Mesentery.  The two laminae, where they depart from the
intestine, are loosely connected with each other, for the pur-
pose of allowing room for the dilatation of the intestine, on
the same principle which is exemplified in regard to the sto-
mach.
  The Muscular Coat is next to the  peritoneal.   Its fibres
are pale, and form a lamina not so thick as common writing
paper.  The superficial  ones  are longitudinal,  not  very
distinct, and too much separated to form a perfect coat. The
others all run in a circular  direction, approaching to the
spiral, and are sufficiently numerous to form a perfect coat;
none of them perform a complete  circuit of the intestine,
but are rather  segments of circles.   This coat is united to
the peritoneal by a thin scattered cellular substance.
  The Cellular Coat of the small intestine, also called the
nervous, like that of the stomach, is only a lamina of con-
densed  cellular  substance, which  serves  as a  medium  of
connexion between the muscular and the mucous coat; and
also conducts to  the latter the blood vessels, nerves, and
lacteals.
  The Mucous Coat is the most internal, and when it has
been cleaned by maceration,  exhibits an opaque pearly co-
lour.   It is remarkable for having its extent very consider-
ably augmented beyond that of the  other  coats; by being
threwn into a great number of permanent folds, or duplica-
tures, which lie one upon another successively, like the shin- 
INTESTINAL CANAL.
31
 gles upon the roof of a house.   These duplicatures are the
 Valvulae Conniventes, and are, for the most part about three
 lines in breadth.  They are either placed in the direction of
 the circumference of the intestine, or are very slightly ob-
 lique; they seldom go all around, but are rather in segments
 of circles, and by being  arranged successively, their  ends
 pass one another, or are connected by slight elevations. They
 are more numerous and broad in the upper than in the lower
 half of the intestinum tenue, and are  evidently intended to
 retard the progress downwards of alimentary matter, and to
 increase the surface for absorption and for exhalation.
   The mucous membrane, on the side which it presents to
 the cavity of  the intestine, is furnished with a great num-
 ber of delicate cylindrical projections, resembling the down
 on the skin of an unripe peach, and  called  Villi, from
 whence the term villous  has also been applied to this coat.
 These villi are to be found in abundance every where;  but
 in the upper half of the intestinum tenue they are so nume-
 rous as to stud its whole surface, and  to be in contact with
 each other.   They are from one-fourth to a  line in length,
 and some of them when  examined with a microscope ap-
 pear flattened  and fungiform.  According to the  estimate
 of  Meckel,* where they  are thickest, every  square inch of
 intestine furnishes about four thousand of them, and by ex-
 tending this computation, with  a proper allowance for di-
 minished  numbers below, their aggregate amount is about
 one million.
  Each Villus is composed of an artery, a vein, and a lym-
 phatic,  all united by cellular substance.  From the extreme
 vascularity of  the mucous membrane,  the  blood  vessels
 readily receive a fine injection  and  thereby become  evi-
 dent, forming  a very delicate vascular network  in each of
 the villi.  It is ascertained that the lymphatic opens on its
 surface, but whether  by  one or more  orifices  is  yet  un-
settled.   According to the celebrated  Lieberkuhn, there
is commonly but one orifice at the end  of each villus,  and
very rarely two; this  assertion he considered  himself as
* Manuel D'Anat. 
ORGANS OF DIGESTION.
having established by passing a current of air through the
villus till it was dried, and then slitting it open.   Hewson,
Cruikshank, and W. Hunter, on the contrary, are said to
have found many more, amounting even to twenty, on such
villi as were gorged with chyle.  The subject has been fruit-
ful with controversy to anatomists, and ranks many distin-
guished champions on each side; but as from the  minute-
ness of the parts under  discussion and the consequent ne-
cessity of microscopical observations, it is exposed to much
fallacy and illusion, it  cannot be  satisfactorily settled,
though the general  analogies of papillary structure are in
favour of the latter authorities.   The more important fact,
however, is ascertained by the admission of all,  that there
is a branch of the lymphatic system in every villus, which
has, for its function,  the absorption of chyle from the cavity
of the intestine.

  An abundance of Mucous Glands is found deposited in
the cellular coat of the small intestine, between the muscu-
lar and the villous;  the ducts of which open upon the in-
ternal surface of the latter,  in the  interstices of the villi,
and from their smallness  require the intestine to be floated
in water and examined with a magnifying glass, before they
can be recognised.   In order to see the glands themselves,
the intestine must be cleaned by soaking it in water; it is
then  to be slit open longitudinally and held between the eye
 and the  light, in which case the glands  appear like little
 points or spots in the thickness of the intestine.   They are
 more abundant in the beginning of the latter, decrease  about
 its middle, and increase again  towards its termination.
 Their structure is very simple, as they consist in a conge-
 ries of blood vessels, terminating in short canals secreting
 mucus.*
   Some  of these glands  are microscopical, and are called
 cryptae;  others are to be found from that size to  a line in
 diameter, and flattened.  They are either  alone or in clus-
 ters.  The former (Glandulae Solitariae. Brunneri) are  found
* Soemmering', de Corp. Hum. Fabrica. 
INTESTINAL CANAL.
33
principally about the duodenum and the neighbouring por-
tion of the small intestine.  The latter (Glandulae  Agmi-
natae,  Peyeri) exist  principally  in  the lower part  of the
small intestine, and are collected into clusters varying from
a few lines to three or four inches in length, but  seldom
more than eight  or nine lines broad.   All of these mucipa-
rous glands are too much  flattened to project sensibly into
the cavity of the intestine, and when they do, there is rea-
son to believe that they are in a diseased  state.   They are
least abundant near the mesentery.

  The Small Intestine, though an uninterrupted tube from
one end to the other, is divided  by anatomists into  Duode-
num, Jejunum, and  Ileum.   There is  some reason  for the
first name, but  the  two latter may be very conveniently
blended, as has  been done by some, under  the  term Me-
senteric Portion of the intestinal canal.
  The Duodenum, named from  its  being about  twelve in-
ches,  or twelve fingers' breadth in length, is nearest to the
stomach; or, in  other words, is  the commencement of the
canal.   It is larger than either of the others, and is, more-
over, susceptible of great dilatation, whence it has also been
called Ventriculus Succenturiatus.  Its direction is much
varied; beginning  at the pylorus it first of all passes upwards
and to the right side, till  it reaches the neck of the gall-
bladder; it then turns downwards  so  as to form  a  right
angle with itself, and descends in front of the right  kidney
to the third lumbar vertebra, being there placed behind the
superior lamina of  the transverse mesocolon.   It then forms
a round  elbow, crosses the spine obliquely in ascending
from  right to  left, and  making  its appearance to the left
of the second lumbar vertebra, is there continued into the
mesenteric portion of intestine.
   The beginning of the duodenum is  moveable, and has a
peritoneal  coat  continued from the lesser  omentum; the
descending and  the transverse portions have no proper pe-
ritoneal coat, but are only loosely fixed between the laminae
of the mesocolon; the  termination is  both moveable and 
34
ORGANS OP DIGESTION.
 has a peritoneal covering, from  being at the commence-
 ment of the mesentery.
   From the course assigned to the duodenum, it is evident
 that it forms the segment of a circle, the concavity of which
 looks to the left side.   This concavity is occupied by the
 head of  the pancreas.   The transverse portion crosses the
 spine below the latter, and is separated from it by the su-
 perior mesenteric artery and by the vena portarum; behind
 it are the crura of the diaphragm, the ascending cava, and
 the aorta.
   The organization of the duodenum is the same with that
 of other  portions of the intestinum tenue.   Its peculiarities
 consist only in a partial deficiency of peritoneal coat, and
 in its augmented size.   Its internal or mucous coat is very
 much  tinged with  bile, abounds in valvulae  conniventes,
 and  about four inches  from  the  pylorus is marked  by a
 small tubercle or elevation, indicative of the orifice of the
 biliary and of the pancreatic ducts.
   The Jejunum and Ileum form the remaining length of the
 small intestine, and have  no  external  marks of difference
 from each other.   They are  strung  along the  mesentery,
 and in consequence of their great length are  thrown into
 folds or  convolutions, which  give to  them a complicated
 appearance.  There is, however,  no  difficulty in tracing
 them regularly from one  end to the other.  They occupy
 the umbilical, the hypogastric, and a part of the  iliac re-
 gions, and are surrounded by the circuit of the colon.   The
 upper two-fifths is the jejunum, and the lower three-fifths
 the ileum.   This distinction, originally introduced  by Ga-
 len,* from a supposition that the jejunum was more fre-
 quently found empty than any other intestine,  has no rigid
anatomical support   The only difference between the two
is, that the  valvulae conniventes, abundant in the whole
length of the jejunum, become less so at the upper part of
the ileum, and finally disappear entirely towards its lower
extremity.   The distinction has therefore been rejected by
* Portal, Anat. Med. 
INTESTINAL CANAL.
35
the  most approved modern authorities,  such as Haller,
Soemmering, Meckel, and so on.
  It sometimes happens, that the intestinum tenue has one
or more blind pouches appended to its  sides and opening
into  its cavity.

  The Mesentery (Mesenteriurn)  is a process of peritone-
um which serves, as mentioned, to connect the intestinum
tenue to the posterior parietes of the abdomen, and extends
its connexions from the left side of the second lumbar ver-
tebra to the right iliac fossa. This attachment, called the root,
is about six inches  in length; whereas its lower circumfe-
rence, which encloses the small intestine by giving it a pe-
ritoneal coat, is of  course the whole length of the bowel,
and  consequently from twenty-three to twenty-seven feet in
length.   This expansion becomes  intelligible  the moment
that  the arrangement of the part is inspected, and is some-
what after the manner of a ruffle, except that it is not puck-
ered at the root.
  The two lamina? of peritoneum which form the mesen-
tery, contain between them the superior mesenteric artery,
and  the corresponding  portion of the vena portarum;  an
abundance of lymphatic or  lacteal glands  and vessels; ra-
mifications from the solar plexus of the sympathetic nerve;
and a considerable quantity  of cellular and of adipose  tis-
sue.   The  superior  lamina  is  continued  directly into the
mesocolon, and at the place of junction the transverse part
of the duodenum is very perceptible beneath.  The lower
lamina descends  along  the posterior  parietes of the  abdo-
men, concealing the large blood vessels there and the ureters.


                Of the Large Intestine.

  The Large Intestine (Intestinum  Crassum) exceeds
much in its  diameter the  small intestine,  and differs also
from it in not being by any means  so regularly cylindrical.
It commences at the inferior end of the small intestine and
terminates  at the anus, describing in this course, as men-
tioned, a circle which surrounds two thirds of the abdomen, 
36
ORGANS OF DIGESTION.
and embraces the intestinum tenue.  Like the latter, though
only a continuous tube, it  is divided into three parts; the
commencement of it, which is below the insertion of the
ileum, and about two inches in length, is the Coecum or Ca-
put Coli; the remaining portion, which occupies almost its
whole length, is called the Colon, until it reaches the pel-
vis, when the name is converted into Rectum.

  The Mesocolon is a reflection or duplication of perito-
neum, that fixes the  large intestine to the posterior parietes
of the abdomen.   This duplicature  is not of a breadth so
uniform  as the mesentery,  but  allows to the  middle of the
large intestine very considerable motion, up and down,  ac-
cording to the distention of the stomach, while the lateral
portions  are  very much confined.   For  example, in the
right iliac fossa the mesocolon is so short that the posterior
surface of the gut is in contact with the iliac fascia, and ad-
heres to  it by loose cellular substance; in the  right and left
lumbar regions the bowel  is immoveably fixed in front of
the kidneys, but in the space between these two points, that
is to say, where the bowel traverses the hypochondriac and
the epigastric or umbilical  regions,  the peritoneal attach-
ment, here called, from its situation, the transverse meso-
colon,  is so long and loose that it forms a  complete and
moveable septum between  the small intestine and the sto-
mach.   In  the left iliac region, again,  the large intestine,
after having  been bound down to the left lumbar, is sud-
denly loosened by an increased breadth of the mesocolon,
which  permits it to form a  large convolution  called  its sig-
moid  flexure.   The  mesocolon is then continued into the
pelvis in front of the sacrum, first of all a little to the left
of the  middle line of the latter, and, as it descends, it gets
directly in front of the middle line.   The portion of it in
the pelvis  is called  mesorectum,  after the   gut which it
serves to attach.
  The composition of the  mesocolon is precisely the same
with that of  the mesentery, though it  be not so thick; it
therefore consists in two laminae of peritoneum, which con-
tain between them some adipose and cellular  matter, along 
INTESTINAL CANAL.                37
with the arteries, the veins, the nerves, and the lymphatic
vessels, and glands belonging to the large intestine.

  When the large intestine is inflated, it is rendered very
obvious that it decreases in size from its commencement to
the lower part of  the sigmoid flexure, it then increases
again in size just above  the  anus.   Its surface is arranged
into three series  or longitudinal rows of projections sepa-
rated by  transverse depressions, the whole corresponding
with an internal cellular arrangement, by the latter surface
being the reverse of the former.
  Its coats, like the small intestine, are four in number; the
peritoneal, the muscular, the  cellular, and the mucous.
  The Peritoneal Coat prevails in its whole extent with the
exception of the lower part of the rectum: on the ascending
and the descending portions of the bowel, however, where
the latter comes in contact with the parietes of the abdo-
men, the peritoneum does not invest it entirely; but the
transverse portion or the arch, as it is called, and the  sig-
moid flexure,  are completely surrounded.
  The surface of this intestine is studded with small  pro-
jections of various  lengths, called  Appendices Epiploicae,
which are small duplicatures of peritoneum containing fat.
  The Muscular  Coat is thin, like that of  the small intes-
tine, and consists in two orders of fibres, the longitudinal,
and the transverse or circular.
  The longitudinal fibres have the peculiarity of being  col-
lected into three equidistant, flattened fasciculi or bands, of
about half an  inch  in breadth, which  begin  by a common
point at the extremity of the coecum, and extend to the up-
per end of the rectum.  One  of them is along the line of
junction with  the mesocolon, another anterior, and the third
inferior.  These fibres, being shorter than the other coats of
the gut,  have  the effect of puckering them into the internal
cellular condition alluded to; for when they are cut through,
the intestine is much elongated, and its cells disappear.  It
occasionally happens that the longitudinal fibres,  instead of
being confined to the bands alluded to, exist in considerable
quantity over the intermediate spaces; in this case the  eel'
  Vol. II.—6 
38
ORGANS OF DIGESTION.
 lular arrangement is restricted,  and in some  instances en-
 tirely dispensed with;  of the  latter, an  example is in the
 Anatomical Museum.
   The circular muscular fibres form a thin semi-transparent
 lamina beneath the last, and do not present any peculiarity
 of interest.
   The Cellular Coat is a condensed thin lamina of cellular
 substance, serving to connect the muscular with the mucous
 coat, and to conduct the  blood vessels  and nerves to their
 terminations on  the latter.
   The Mucous Coat lines smoothly the internal face of the
 cellular, and has no doublings or folds, exclusively in it,
 like the valvulae conniventes of  the  small intestine.   The
 transverse projections which it makes between the longitu-
 dinal bands, into the cavity of the gut, and separating the
 cells of the large intestine from  each other,  are not mere
 duplicatures of it alone, but are  also constituted by the other
 coats.
   Near its commencement this coat has the fungous appear-
 ance of the stomach, but about the sigmoid flexure it has a
 plane, smooth, and,  to a degree, a polished surface.  It has
 but few villi, such as exist in the  small intestine; indeed,
 by some anatomists it is denied that it has any. Its mucipa-
 rous glands and follicles are numerous, and when somewhat
 enlarged, they project; they are unusually conspicuous about
 the sigmoid flexure and in the rectum.  Its lacteals are not
 abundant.

   Each division of the large intestine has some peculiari-
 ties of structure and connexion; which  may now be  at-
tended to.

   The Coecum, or  Caput Coli, is generally from an inch
 and a half to two inches long, has  a rounded termination be-
 low and somewhat to the left, from which proceeds an in-
testinal process, the Appendicula  Vermiformis.  The latter
 is  from three to four inches long,  is cylindrical, has a dia-
 meter of two or three lines, and  consists also  of the same
number of  coats, having the same structure with  other 
INTESTINAL CANAL.
39
 portions of the intestinal canal; its base is  the point from
 which the three longitudinal bands start.  It is attached by
 a narrow duplicature  of peritoneum,  a process of the me-
 sentery, which permits it to float loosely in the abdomen.
 It seldom contains faeces, but is kept distended by flatus.
   The coecum, as mentioned, is for the most part  confined
 to the right iliac fossa, but we very frequently see it with
 a length of peritoneal attachment permitting it to descend
 for a short distance into the pelvis.

   The Ileo-colic  Valve (Valvula  Bauhini)  is formed at
 the junction of the ileum with the caput coli.  This valve,
 destined to prevent the return of  faecal  matter  from the
 large into the small intestine, consists in a transverse ellip-
 tical opening, or slit,  whose lips become  approximated in
 the distentions of the  colon.  The ileum runs  into the left
 wall of the large  intestine, and continues its  cellular  and
 mucous coats into the corresponding  coats of the latter.  The
 circular muscular fibres of the large intestine separate to a
 certain degree to permit this introduction,  but their further
 separation is restrained at each commissure or corner of the
 lips, by  a blending of the structure, aided  by a  few liga-
 mentous fibres, designated  as the retinacula of Bauhin or
 of Morgagni; which, however,  are frequently not very dis-
 tinct.  The lips themselves, formed  principally by the mu-
 cous membrane, approach one another  after the manner of
 the ship  dock or hydraulic gate; the superior is somewhat
 broader than the inferior.   Their power as well  as their
 existence depend entirely on the tension which is kept up
 by the natural connexions of the parts; for a very slight dis-
 section causes them to become almost effaced, and, instead
 of forming an elliptical transverse opening, to be converted
 into  a round patulous one.

  The Colon, properly speaking, has  some regional  dis-
tinctions which are serviceable to accurate description.  The
 right lumbar  colon, which is bordered in front by the small
intestine and behind by the  right kidney, extends  from the 
40
ORGANS OF DIGESTION.
ileo-colic valve, to the margin of the  false ribs of the cor-
responding side.   The transverse colon, bordered above by
the stomach and  below by the small  intestine, goes from
one hypochondriac region to the other.  It is  generally
found more distended than the other portions. The left lum-
bar colon descends from the hypochondriac region of the
left side to the sigmoid flexure, being bordered behind by
the left kidney and in front by the small intestine. The sig-
moid flexure, placed in the  left iliac fossa, forms a convo-
lution but very indifferently described by the term applied
to it.   It is occasionally  very long and  loose, and termi-
nates at the left  sacro-iliac symphysis.   It is not infre-
quently found destitute of the partitions  which prevail in
other parts.

   The Rectum begins at the  left sacro-iliac symphysis, and
passes obliquely downwards  to  the centre of the  sacrum,
thence  in  front of the middle line of the sacrum, and of
the coccyx, to terminate  at  the point of the latter.   It is
not regularly cylindrical,  but, just above the anus, is dilated
into a wide pouch, flattened from before  backwards by the
pressure of the bladder, and very distinguishable upon the
introduction of the finger, for it is but seldom in a contract-
ed state.   It of course has a flexure in it adapting itself to
the concavity  of the sacrum, and is bounded in front by the
bladder, the prostate gland and  the vesiculae  seminales of
the male, and  by the vagina  and the  uterus of the female.
   The  peritoneum covers only the superior two-thirds of
the rectum, and attaches it, by the short  duplicature called
the mesorectum, to the front of the sacrum. A small pouch,
passing down between the vesiculae seminales almost to the
base of the prostate, is formed  by the peritoneum  in  its
course from the rectum to the bladder.
   The muscular coat of the rectum has a thickness and red-
ness surpassing much that of any other intestine, and is di-
vided very clearly into two laminae, the external of which
consists in longitudinal and  the internal in circular fibres.
The external forms in itself a complete coat continuous with 
    GENERAL ANAT0M1' OF THE MUCOUS MEMBRANES.   41

the longitudinal bands of the colon, but  is much  increased
by additional fibres.   The circular fibres also form a com-
plete coat, and, just below the pouch of the rectum,  are
multiplied so much for eight or ten lines as to be a perfect
internal sphincter muscle,  bearing a strong analogy with
the pyloric muscle of the  stomach.  At  the anus, an  ar-
rangement of the  muscular  coat prevails, which, as far as I
know,  has not been heretofore attended to by anatomists.
The longitudinal fibres, having got  to  the lower margin
of the internal sphincter, turn  under  this  margin between
it and the external sphincter, and  then ascend upwards
for  an  inch or two in contact with  the  mucous coat, into
which  they are finally inserted.   This  connexion must
have obviously much influence in the  protrusions of the mu-
cous coat, which  sometimes take place.
  The mucous coat of the  rectum is thick, red, and fun-
gous, and abounds in  mucous lacunae  and glands.  It is
smoothly laid above, but below it is thrown into superficial
longitudinal folds called columns.  The wrinkling of  the
anus is from the influence of the external sphincter ani mus-
cle.  In some subjects large cells are formed in the cavity
of the rectum by transverse doublings of the mucous coat
only, resembling the  valvulae  conniventes of the small in-
testine; this, however, is not the most frequent arrange-
ment, though deserving of notice.
  The large intestine is supplied with blood from a part of
the superior mesenteric, from  the whole of the inferior me-
senteric, and  from the internal  pudic  artery.   Its veins
empty into the vena portarum.   Its nerves are  derived
from the solar and the hypogastric  plexus of the sympa-
thetic.

  SECT. III.--OP THE GENERAL ANATOMY OF THE MUCOUS
                      MEMBRANES.

  The extent of the mucous  coat of the alimentary canal,
and the important and varied sympathies which it has with
most other parts of the body,  render useful some remarks 
42
ORGANS OF DIGESTION.
 on membranes of this kind generally.  Mucous Membranes'
 are so called from the nature of the secretion  which they
 furnish: and the term having been first applied to the lining
 coat of the nose, a similitude of character has caused its ex-
 tension to that of other organs.  The celebrated Bichat, the
 founder of the science of general anatomy, was the first to
 adopt fully, and to perceive the value of this classification;
 since which it has been almost universally received by ana-
 tomists.
   As the skin forms an external covering to the body, so
 mucous membrane lines the internal surface  of the hollow
 viscera.   When it is recollected that this membrane forms
 an internal tegument to  the  whole  alimentary canal, from
 the mouth to the anus; to all of the  urinary and genital ap-
 paratus;  to the whole respiratory system, from the nose
 down the trachea and throughout the lungs;  it will be ad-
 mitted that in its extension it exceeds much that of the skin.
   A  mucous membrane presents two surfaces, one of which
 adheres to the  contiguous parts, and  the other is  free  by
 being internal.  The adherent surface is attached by a cel-
 lular structure somewhat condensed.   This cellular struc-
 ture is principally remarkable for its want of disposition to
 secrete fat into its interstices; a property of  immense  im-
 portance, as without it, obstructions would be  continually
 occurring to the destruction of life: it is pervaded by a mul-
 titude of fine vessels and nerves, running forward to be spent
 upon the mucous membrane; and has been  unfortunately
 named nervous coat, by anatomists of high authority.  The
 strength of attachment which it furnishes is somewhat va-
 ried;  for example, in the small intestinal canal  I have of-
 ten seen the mucous  membrane caught at one end and en-
tirely withdrawn from the other coats, an experiment which
 alone can give rigid ideas of its greater length, as by it all
 the duplicatures or valvulae conniventes are stretched out.
The experiment succeeds much more  certainly by the regu-
lar pressure of a column of water between the tunics of the
intestine. The mucous membrane of most organs is arranged
into wrinkles and duplicatures, for the purpose of augment- 
     GENERAL ANATOMY OP THE MUCOUS MEMBRANES.  43

 ing its extent.  This  arrangement  prevails in the nose,
 and, as mentioned, in the oesophagus, in the stomach and
 intestines; to  say nothing of many other instances which
 are noticed in the description of  each organ.  In some ex-
 amples they  are permanent, and  in others depend  on the
 state of contraction of an exterior muscular coat.  The in-
 terior face of the mucous membranes, allowance being made
 for the inequalities just stated,  moreover presents,  when
 closely viewed, an abundance of  more  minute depressions
 and of elevations, causing it to resemble velvet.   Some of
 these depressions  are so large as to give it a cellular ap-
 pearance, as  in many parts of the intestinal  canal, and the
 gall-bladder, and  have been  particularly described  by Sir
 Everard Home.

   In regard  to organization, the  mucous membranes are  of
 a soft, spongy  consistence;  easily yield to mechanical vio-
 lence; and depend for their strength upon the surrounding
 cellular coat.  They are not of a uniform  thickness; for
 example,  they  are much thinner  in the urinary and genital
 apparatus, than in the  alimentary canal;  they also present
 some varieties  of consistence.  They yield very readily  to
 putrefaction, and are quickly reduced to a pulpy state by
 the  action of the  mineral acids.   Caustics of all kinds act
 more promptly on them than on the  skin, owing  to the
 protection of the  latter by the  epidermis;  Bichat  states,
 that in the practice  of the Hotel Dieu, this effect  is fre-
 quently exemplified, by the administration of lunar caustic
 among the common people for the purpose of poisoning.
 The nitric acid leaving the silver, quickly applies itself  to
 the mucous membrane t)f the stomach, and disorganizing it,
 forms  a whitish eschar,  which,  if life is preserved long
 enough, is finally detached in a membranous form.
   One of the remarkable properties of the mucous surfaces
 of the stomach and intestines is, that of t coagulating milk.
 According to the experiments  of Spallanzani,  the  gastric
juice, in the  living state, assists  in  this change; but it  is
 perfectly  well  known in domestic affairs, that the dried 
44
ORGANS OP DIGESTION.
stomach  of a calf, where the juices have been completely
evaporated, is also productive of it.  The observations of
the same author led him to conclude, that the peritoneal and
the muscular tunics  of the stomach are insufficient to pro-
duce this effect.
  The internal surface of all the  mucous membranes is fur-
nished with small projecting points or spiculae, called pa-
pillae  or  villi.  They are particularly conspicuous and nu-
merous,  as mentioned, on the upper surface of the tongue
and in the small intestine, and bear an analogy of function
and organization with the very fine papillae which are seen
every where on the  surface of the cutis vera.   It is to be
remembered that in the stomach their organization is suited
to the secretion of gastric juice, and that in the  intestines
the origin of  the lacteals is interwoven with them.  These
papillae are every where furnished with nervous filaments,
giving them a high degree of sensibility; and with an abun-
dance  of blood vessels.  The term papillae has been more
exclusively applied to the projections on the surface of the
tongue, from their greater size; they are there also more
distinctly covered with an epidermis, frequently called epi-
thelium.   The villi, from their connexion with the process
of digestion, have been emphatically denominated the roots
of animals.  According to M. Beclard,* who has examined
them upon a plan of his own contrivance well suited to ac-
curate  microscopal observation, they are presented under a
diversity of shapes.   Those of the pyloric half of the sto-
mach  and of the duodenum  being broader than  they are
long,  are composed  of very small thin laminae,  having a
tufted  arrangement.   Those of the jejunum are  long and
narrow, having more the form commonly assigned to them,
while in  the lower part of the ileum and in the colon  they
again become laminated.
  It should be observed that notwithstanding the assertion
of Lewenhoeck, Hewson, Hunter, and  others, the fact is
still called  in  question, by two  of the most distinguished
anatomists of the  present time,  MM. Beclard and J. F.
* Anat. Gen. p. 253. 
    GENERAL ANATOMY OF THE MUCOUS MEMBRANES.   45

Meckel, whether the orifices of the lacteals are, under any
circumstances, visible on the surface of the villi.  Admit-
ting that they do not open as stated, the power of intersti-
tial absorption in the mucous membrane will still account
for the chyle finally getting into the lacteals, as well as for
fluids getting into the circulation from the stomach, when
its continuity with the intestinal canal has been interrupted.
  The Epidermis or Epithelium of mucous membranes is
very distinct at their external orifices, but becomes less and
less apparent towards the  interior of the body,  until finally
it cannot be seen at all; and the probability is that it is en-
tirely  deficient,  notwithstanding  the assertion  of Haller
to the contrary.   A pathological proof may be brought to
our aid in settling this question.  It is a matter of common
observation,  that when the interior of mucous membranes
is exposed by an eversion for a long time, to the action of
the atmosphere, they take on more of the structure of skin,
and become  evidently covered  with  a cuticle  which  pro-
tects them and  diminishes their secretion.   This is exem-
plified in eversion of the vagina from prolapsed uterus, in
elongated and tumid  labia interna, and in other ways; re-
store  the parts  to  their natural  situation,  and  they are
brought  back to their original structure.  In  the partial
prolapse of  the mucous  membrane  of the  rectum,  from
piles, corresponding  circumstances occur.  From this we
infer, that the development of cuticle depends very much
upon the degree of exposure which any surface of the body
has to undergo.  The reverse also  takes place: shut up
or close any  surface  of the skin so that it is put on the foot-
ing of an interior cavity, and it immediately begins to as-
similate  itself to a mucous membrane.  This is proved by
the tendency in young children to a detachment of the cu-
ticle, or  excoriation  of the  opposed  surfaces  of the deep
wrinkles about  their  thighs and in their perineum; a ten-
dency  obviated by  the habit of nurses of covering  these
surfaces  with powdered starch.  It is also manifested fre-
quently in the dressing of wounds with sticking plaster,
where an incautious approximation of the contiguous sur-
faces of skin, not only is followed by excoriation, but even
   Vol.  II.—7 
■Hi
ORGANS 01r DIGESTION.
by ulceration; a fact,  the importance  of which used to be
set in proper relief by Dr. Physick in  his surgical lectures,
and of which I have seen an example  in a case of extirpa-
ted female mamma.

  The mucous membranes vary in colour from a very light
pink to a deep red, which is owing to  the blood that  circu-
lates in them.  In cases of  suffocation they become almost
brown from the congestion of blood in them, while in fainting
they turn white from the desertion of the latter.  These ves-
sels, after having penetrated the thickness of the membrane,
ramify with extreme  minuteness on its surface.  In conse-
quence of this superficial situation, the vessels being unsup-
ported on one side, are exposed to rupture from slight con-
cussions; in this way hemorrhage is produced in the lungs
from coughing, and bleeding at the nose from blows upon
the head.
  Exhalent vessels exist in great numbers in the mucous
membranes;  this is especially the case in the lungs, where
the  pulmonary perspiration, as it is called, is very obvious
to common  observation.   Elsewhere, this  discharge is so
much  blended with the mucus of the part that it is difficult
to appreciate its quantity.    From the superficial situation
of the blood vessels, it is clear that the exhalent orifices or
pores, have but a short course to run.   This is considered
by Bichat as a satisfactory reason for  the  tendency of the
blood to escape through them, or to ooze out where there
is no rupture.
  Absorbents exist also in great numbers, as proved  by the
absorption of chyle, of watery drinks from the intestinal ca-
nal; and by the inhalation of the vapour of spirits of turpen-
tine into the lungs, rapidly communicating the particular
smell of this article to the urine.   There are,  moreover,
cases recorded of obstructed urethra, where the urine has
been almost entirely absorbed by the mucous coat  of the
bladder.
   In regard to nerves, the mucous membranes are well fur-
nished with  them.    Bichat  has remarked that, wherever 
     GENERAL ANATOMY OF THE MUCOUS MEMBRANES.  47

 these membranes are situated  near the surface of the body
 and enjoy common sensibility, they are almost wholly fur-
 nished from the central portions of the nervous system; this
 is exemplified in the conjunctiva, the pituitary membrane,
 the palate, the glans penis, &c.   On the contrary, the sym-
 pathetic nerve furnishes the intestines, the bladder, and the
 excretory tubes generally.
   Mucous Glands, as they are called, exist throughout the
 system of mucous membranes, being situated either under
 them or in  their thicknesses.   From them is derived the
 mucilaginous fluid which  lubricates so abundantly their in-
 terior surfaces, so as to facilitate the  passage of extraneous
 bodies, and, at  the same time,  to protect the membrane
 from mechanical violence.   These  glands are of various
 sizes, from that of the tonsils  and the muciparous glands
 on the lips, cheeks, and root of the  tongue, to the almost
 imperceptible cryptae of the bladder  and urethra.   Their
 shape is either lenticular, rounded, or that of a pouch.   The
 two  former have their parietes of a sensible thickness, but
 the last are too thin to be distinguished  from  the mucous
 membrane itself.   For the most part the excretory duct of
 these glands is short and patulous, so as to lead directly into
 the substance of the gland.    This is remarkably the case
 with the tonsils, which consist in a congeries of these folli-
 cles; and with  the glands on the root of the tongue.   In
 some animals they are so numerous as to form almost  a dis-
 tinct lamina to the intestines; after the manner of the human
 subject, on the palate and parietes of the mouth.
   The Mucosity discharged from these glands is one of the
 principles of animals,  and, as is well  known, exists also to
 a great extent in some vegetables.    When perfectly pure
 and fluid, it is white, transparent, inodorous,  and insipid.
 It is insoluble in alcohol, but soluble in acids.  Water form,s
more than nine  tenths of it, the remainder is mucus, pro-
perly speaking, blended with some neutral salts of soda and
 potash.

   The  mucous membranes are exposed to a  multitude of
 morbid alterations,  such as polypus, scirrhus, cancer, phleg- 
48
ORGANS OF DIGESTION.
morrhagiae or serous fluxes, blenorrhagiae or mucous fluxes,
inflammation in all its forms, gangrene, ulcerations, and
congestions.
                   CHAPTER  IV.

       OF THE ASSISTANT CHYLOPOIETIC VISCERA,

                SECT. I.--OF THE LIVER.

  The Liver (Hepar, Jecur) is the largest glandular body
in the human frame.  It, as  mentioned, occupies the whole
of the right hypochondriac region, the upper half of the epi-
gastric, and, as it becomes thinner in going towards the left
side, it occupies a small space in the right superior part of
the  left hypochondriac region.   Its whole  superior face is
in contact with the diaphragm; on the left it is bounded by
the  spleen, and below by the stomach and the transverse
colon;  behind it, are the vertebral column and the ascend-
ing cava.
  The shape of the  liver is like one half of an ovoidal body
cut  into two in the direction of its long diameter, and having
the thick end  turned to the right side.   It  is about ten
inches  in length by six or seven wide, and weighs from four
to five  pounds in the adult.  Its colour is a reddish brown,
generally, though, on its under surface and  about its edges,
broad blue or black patches are constantly met with, which
do not indicate any  morbid derangement.
  Its upper  surface  is of a uniform convexity, rather more
prominent at the right posterior part than  elsewhere; ad-
justs itself accurately into the concavity made by the under
surface of the diaphragm; and is unequally divided from be-
fore backwards by the suspensory ligament.   The anterior
margin is thin, and is notched  where the suspensory liga- 
THE liver.
49
ment begins; the posterior margin is much thicker, and has
near its middle a broad depression, to fit it to the projection
of the vertebral column.  The ascending vena cava forms a
superficial sulcus upon this margin, and frequently there is
a complete  canal  through the substance  of the liver  for
transmitting it.   The right extremity is very thick, and
almost fills the hypochondriac region of that side, while the
left extremity is reduced to a thin, tapering, and flexible
edge.
  The under surface of the liver is much more irregular than
the upper; it is traversed in an  antero  posterior direction,
in a line corresponding with the attachment above of the sus-
pensory ligament,  by the umbilical fissure, (Sulcus Umbili-
calis) which extends from the notch in the front edge to the
depression behind, and obtains its name from having accom-
modated in the foetal state, the umbilical vein, now convert-
ed into a round ligamentous cord.   In the posterior part of
this  fissure  is likewise to be seen, in the same condition,
what remains of the ductus venosus.  The anterior portion
of the umbilical fissure is not unfrequently converted into a
complete canal, by a portion of hepatic substance crossing it
like a small bridge.   The transverse fissure (Sulcus Trans-
versa, Intermedius) is situated in the middle  of  the under
surface of the liver, and extends along a third or a fourth of
the long diameter  of the latter.   It begins somewhat to  the
left  of  the  umbilical fissure, and, crossing  it at right  an-
gles,  proceeds towards the right extremity.  It contains the
vena portarum, the hepatic artery, and the hepatic duct; all
of which, are bound to each other by a close cellular sub-
stance.
   The suspensory  ligament above, and the umbilical fissure
below,  give occasion  to  divide the liver into Lobes; right,
and left; of which  the right  is by much  the largest, and ac-
commodates almost entirely the  transverse  fissure, having
also on its under surface some subordinate elevations, to wit,
the Lobulus Spigelii and the Lobulus Quartus, together with
the Gail-Bladder.
   The Lobulus Spigelii is placed between the transverse fis- 
50
ORGANS OF DIGESTION.
sure and the posterior margin of the liver, to the right of the
posterior end of the umbilical fissure.  Its shape is somewhat
prismatic, bifurcating in front; one of  the  elongations is a
papilla overhanging the transverse fissure, and  is therefore
considered as one side of the gateway (porta) opened for the
vena portarum; the other elongation is a small ridge, some-
times called Lobulus Caudatus, and is lost gradually on the
under surface of the great lobe, by inclining to the right.
  The Lobulus Quartus, Anonymus, not by any means so
elevated as the last, but having a flattened surface, is placed
in front of the transverse fissure, between the fore end of the
umbilical fissure and the gall-bladder; its posterior extremity
is the second porta of the Liver, and is just opposite that fur-
nished by the Lobulus Spigelii.
  The liver, from being completely enveloped in peritoneum,
has a smooth glossy appearance.  The reflections  of this
membrane, from it to the parietes of the abdomen, form the
ligaments  as they are called, which consist each of two
laminae.  The Falciform Ligament, or Suspensory, contain-
ing in its anterior margin the remains of the umbilical  vein,
now called Ligamentum Teres, begins at the umbilicus, ex-
tends from it along the linea alba and the middle line of the
diaphragm,  and, as mentioned, is reflected to the upper sur-
face of the liver, from the anterior to the posterior margin.
The Right Lateral Ligament is situated behind, and departs
from the back part of the diaphragm to the posterior margin
of the right lobe.  The Left Lateral Ligament also goes from
the back part of the diaphragm, and is attached along the
posterior margin of the left lobe. Where the suspensory liga-
ment inclines on each side into the lateral, it passes with so
much obliquity as to leave some portion of the posterior mar-
gin of the liver uncovered by peritoneum; the latter, where
it describes the periphery of this space,  has been rather un-
necessarily designated as the Coronary Ligament.
  In addition to the peritoneal coat, the liver has another
connecting it with the peritoneum, and  seeming to be only
condensed cellular substance, which also penetrates into the
substance of the gland, and holds its constituent parts toge- 
THE LIVER.
51
ther.   It is particularly well seen within the circle of the
coronary ligament.


           Of the Organization of the Liver.

  The Liver, besides its glandularjsubstance, is extremely
vascular, and is formed principally by the ramifications of
three kinds of blood vessels, the Vena Portarum, the Hepatic
Artery, and the Hepatic Veins.    The two first convey the
blood to it, and the third removes it again, into the general
circulation, by emptying into the ascending vena cava. There
are also branches of the hepatic duct, lymphatic vessels, and
nerves.
   The glandular  substance is fragile  and easily lacerated;
when torn it assumes the appearance of a congeries of sphe-
rical  or polyedrical grains,  (acini,) united in mass by the
elongations of the cellular  coat,  and traversed by the trunks
of the blood vessels.  Each of  these  granulations is about
the size of a millet seed, and is a representative of the en-
tire gland, as its structure is complete in itself, being formed
by the terminations of the blood vessels, and by the origin
of a branch of the hepatic duct,  called the porus biliarius.
When examined with a microscope,  it is said  that those
acini are composed of a yellow and of a brown looking sub-
stance; it has not, however, occurred to  me to see the dis-
tinction in a very satisfactory way.

   The Vena  Portarum  having  arisen from the junction of
all the veins of the stomach,  intestines,  pancreas,  and
 spleen, is about three inches in  length when it reaches the
transverse fissure, by going  over the  duodenum and under
 the pancreas.  It immediately  divides into two  branches,
 called  collectively the Sinus Venae Portarum, which is at
 right angles with the trunk of the vein; the  right branch
 being the shortest and  largest,  is distributed by radiating
 trunks to the right lobe of the  liver;  the left branch is dis-
 tributed, after the same manner, to the left lobe, to the lo-
 bulus spigelii,  and  to  the  lobulus quartus.   Some of its 
52
ORGANS OF DIGESTION.
branches anastomose with the hepatic veins, which accounts
for the ease  with which an injection will pass  from one
to the other.   Other branches of a smaller description anas-
tomose with the pori biliarii, but with less freedom than in
the preceding case; and  lastly the most delicate ramifica-
tions are spent upon the  cortical or  yellow matter of the
acini, without penetrating to the brown.:-

  The Hepatic Artery is a branch of the cceliac, and in ap-
proaching the transverse fissure divides into three or more
branches, that penetrate the substance of the liver, between
the sinus portarum  and the ducts as  they come out; one
branch goes to the right lobe, another to the left, and a third
to the lobulus spigelii.   There is some variety  in regard to
the precise mode of distribution, and their division into
subordinate ramifications frequently occurs before they get
fairly into the substance of the liver.  When  there, they
seem to be intended for the nourishment of this organ, ac-
cording to the observations of several  able anatomists; and
follow the ramifications of  the vena  portarum and of the
biliary ducts, forming  upon them a very delicate and com-
plicated tissue of anastomosing vessels, some of which, pro-
bably the vasa vasorum, communicate with the  vena por-
tarum.

   The Pori Biliarii, or the commencing ramifications of the
biliary duct,  take their origin in the acini; and,  as is said,
upon the boundary between the two kinds of matter, avoid-
ing the  brown and passing through the cortical, t  The
larger branches converge  into their  respective trunks suc-
cessively or in pairs; while the primordial, or most minute
ones, converge several of them to the same point, giving a
penicillous appearance.   It is asserted that a fine injection
passes more readily from them into the lymphatics than into
any other  order of vessels, which  may account  for  the
promptitude  of jaundice upon an obstruction of the hepatic
duct.

    * Mappes, I. F. Meckel, loc. cit.      i I. F. Meckel, loc. cit. 
THE LIVER.
53
   The Hepatic Veins arise in the  acini from the capillary
 terminations of the vena  portarum and the hepatic artery.
 Their branches are successively accumulated into three large
 trunks, the collective area of which vastly exceeds that of
 the vessels bringing  the blood to the liver.  Two of these
 trunks come from the right lobe and one from the left, to
 empty into the ascending cava, while it is still in contact
 with the liver, immediately below  the diaphragm; just be-
 low the preceding trunks there are five or six, sometimes
 more small hepatic veins,  coming from the posterior margin
 of the liver,  and from the lobulus spigelii.  The hepatic
 veins are destitute of valves, and remarkable  for the thin-
 ness  of their parietes.  An injection passes readily from
 them into the other systems of vessels.   They may be re-
 cognised by their insulated course, by their  consisting in
 trunks which converge from the periphery of the liver to
 the vena cava, while  all the other vessels diverge  from the
 transverse fissure to the periphery, and consequently cross
 the course of the hepatic veins.

  At the bottom  of the transverse  fissure of the liver is to
 be found a condensed  cellular fibrous tissue, which invests
 the vena portarum,  the  hepatic  artery,  and the biliary
 ducts; and, as they all keep together in  their ramifications,
 this tissue follows them  throughout  the substance of  the
 liver, and thereby forms sheaths for them.  It may be con-
sidered as continuous with the processes  sent in from the
cellular coat; and contrary to the opinion of Glisson, whose
capsule it has been called, it is devoid of muscular structure.


                  Of the  Gall-Bladder.

  The Gall-Bladder (Cistis Felled) is a  reservoir for  the
bile secreted by the liver.  It is fixed on the under surface
of the great lobe, to the right of the umbilical fissure, and
removed from  the latter by the lobulus  quartus.  It is an
oblong pyriform sac,  having its anterior extremity or fun-
  VOL. II—8 
 54               ORGANS OF DIGESTION.

 dus projecting somewhat beyond the anterior margin of the
 liver, while the posterior end reaches to the transverse fis-
 sure.  Its long diameter inclines slightly to the right side,
 so that it is not  precisely in an antero-posterior  line.   It
 varies in its shape in different subjects,  being  much more
 spheroidal in some than in others.   Its fundus  is round-
 ed and obtuse, while the posterior end is gradually reduced
 to a narrow neck, which is bent up on itself, so as to retard
 the flow of a fluid through it.   Its upper surface is in con-
 tact with the substance of the liver, and is received into a
 broad shallow fossa,  while the lower surface is projecting,
 and by coming in contact with  the transverse colon, tinges
 it with bile, by transudation after death.

   The Gall-Bladder has three coats, a peritoneal, a cellular,
 and a mucous one.
   The Peritoneal Coat is not complete, but only covers that
 part of the sac not received into the fossa on the under sur-
 face of the liver; it is, therefore, a continuation of the pe-
 ritoneal coat of the latter; sometimes, however,  the gall-
 bladder is  so  loosely attached to the liver  that it almost
 hangs off from it, in which case the peritoneal coat is nearly
 complete.
   The second coat is condensed cellular membrane.  Through
 it ramifies a great number of lymphatics, and blood vessels;
 below, it attaches the peritoneal to the  mucous coat, and
 above, the latter to the liver.
   The Mucous Coat is  always tinged of a deep  green or
 yellow, by the bile which it contains percolating after death;
 for it is  said to  be,  before  that, of a light colour.  This
 coat is thrown into irregular tortuous folds or wrinkles of
 extreme  delicacy, in the intervals of which are many round
 or polyedrous cells, causing it to look, when floated in wa-
 ter, like  a fine honeycomb; such as are about the fundus of
the sac are superficial, and not  so distinct; but those near
 its middle and about the neck, are a line or a line and a half
 deep.  In the neck or apex,  and in the beginning of the
 cystic duct,  are from  three to seven, sometimes twelve, se-
 milunar duplicatures of the internal membrane, which also 
THE LIVER.
55
 retard the flux and afflux of any fluid,  though they do not
 afford so much resistance to the ingress as to the egress of
 it.  These  duplicatures are sometimes arranged into a spiral
 valve, projecting from the  inside of the duct,  and forming
 two or three turns.*  Very small mucous follicles  exist
 over the internal face of  this membrane,  the  discharge of
 which fills the gall-bladder  when the  secretion of bile has
 been interrupted by diseased  action, as in yellow fever, or
 by scirrhus of the liver.
   The artery of the gall-bladder is a branch of the hepatic.
 Its veins empty into the vena portarum.   Its nerves come
 from the sympathetic, and its lymphatics join those of the
 liver.


                 Of the  Biliary Ducts.

   A succession of very fine branches having arisen from the
 acini of the liver,  these branches are united into three or
 four trunks by the  time they reach the transverse fissure.
 These trunks then coalesce into a single one, the Hepatic, of
 eighteen or twenty lines in length, and about the diameter of
 a writing quill.   The Hepatic Duct is then joined at a very
 acute angle with the duct from  the gall-bladder,  which is
 somewhat shorter and smaller; the union of the two forms
 the Ductus Communis Choledochus. The latter is larger than
 either of the others singly, and is three or three and a half
inches long; it descends behind  the right extremity of the
pancreas through its substance, passes for an inch obliquely
between the coats of the  duodenum, becoming at the same
time diminished in  diameter;  and finally ends by an orifice
still more contracted, on the internal face of this gut, in its
second turn, and about three  or four inches from the stomach,
The orifice is marked by a small surrounding tubercle some-
what obscured by the valvulae conniventes.
  The Biliary Ducts are situated along the right margin of

  *  Discovered latterly by M. Amussat of Paris.  M. Amussat has also de-
 tected muscular fibres in the gall-bladder and biliary ducts, in which we
see an analogy with other hollow viscera.—Am. Med. Jour, vol, ii. p. 193. 
56
ORGANS OF DIGESTION.
the lesser omentum, and  have the vena portarum and the
hepatic artery to their left. The reflection of the peritoneum
along with the cellular substance which includes these several
parts, is spoken of frequently under the term Capsule of
Glisson.
  The bile ducts are formed by two coats; the external is a
fibrous, lamellated, and very extensible membrane, while the
internal is mucous, having the same structure with that of
the gall-bladder, of which it is in direct continuation.  In
the Cystic Duct, and at the lower part of the Common Duct,
are several longitudinal  folds.  The Common Duct some-
times receives, just before it empties into the duodenum, the
pancreatic duct.

                     Of the Bile.

   This secretion from the liver, is of a deep  yellow, some-
times green colour; when recently secreted,  it is thin and
fluid; but after it has been conveyed to the gall-bladder, and
permitted to remain there for some time, it becomes as thick
as molasses, and increases also in the intensity of its colour
and in bitterness.   Some anatomists have believed that there
was a more direct communication between the liver and the
gall-bladder than  that through the  hepatic and  the cystic
duct; but repeated and close  observations have proved the
opinion  to be erroneous, or, at  least, destitute  of proper
proof;  it is,  therefore clear, that the difference between
the hepatic and the cystic bile, depends upon the watery par-
ticles being removed from the latter, by the absorbing pow-
er of the internal coat of the gall-bladder.
   According  to Berzelius the chemical analysis of bile fur-
nishes about eighty parts of water, eight of a particular sub-
stance which assumes a resinous condition on the application
 of an acid; three of mucus; and  nine of saline matters, of
 which soda is a principal constituent. 
THE SPLEEN.
57
               SECT.  II.--OF THE SPLEEN.

  The Spleen (Lien, Splen) is situated deeply in the poste-
rior part of the left hypochondriac region, and is bounded
above by the diaphragm, below by the colon, and  on the
right  by the great end of the stomach,  and by the pan-
creas.
  Its  colour varies from a deep blue  to a dark brown.   In
shape it resembles the longitudinal section of an oval, being
flat or very slightly concave on the surface next to the sto-
mach and  convex on  that  contiguous to the  diaphragm.
Occasionally its margins are notched, but this is not invari-
ably the case.  Its flat surface is slightly depressed longitu-
dinally in the centre, where the blood vessels enter it by six
or eight foramina.
  Several spleens sometimes exist in the same individual,
in which case the supernumerary ones are not larger than
nutmegs.   The common size of this organ is about four and a
half inches long, by two and a half or three wide, in which
case it has  a solid firm feel; but it very often exceeds these
dimensions; its transition and varieties of magnitude are so
frequent, that no  settled rule can be established.   In its in-
ordinate enlargements I have seen it only slightly  smaller
than the liver, its texture in this case is  soft and easily la-
cerated .
  It is  fixed in its place by three points of reflection or
processes of peritoneum, whose names indicate sufficiently
their  places of attachment.   They are the Gastro-Splenic
Ligament,  in which are the vasa brevia of the stomach; the
Splenico-Phrenic; and  the Splenico-Colic.   These reflec-
tions by being continued over the  spleen, give it a complete
peritoneal  coat, which  is raised  up  with more difficulty,
than the corresponding  membrane of any other Viscus of
the abdomen.
  The  Internal or proper coat of the  spleen is a grayish,
compact, extensible, and elastic membrane, the use of which 
58
ORGANS OP DIGESTION.
 is evidently to sustain the natural shape of the  organ, and
 to support its parenchymatous structure.   It sends in pro-
 cesses to accompany the blood vessels, and from its internal
 face there proceeds a multitude of lamellae and of fibres,
 which traverse its cavity in every direction, and reduce it
 into a cellular condition  not unlike the spongy structure of
 bones.
   The spleen, in proportion to its size, is furnished to a re-
 markable degree with blood.   The  largest branch of the
 cceliac artery  runs  to  it along the superior margin of the
 pancreas, forming  numerous  serpentine flexures, and dis-
 tinguished for its thickness; it divides into several trunks
 for penetrating into the spleen, and enters by the foramina
 in the fissure.   The veins come out by a number of trunks
 equal to what the artery is divided into; they assemble then
 into a single trunk, which attends the artery along the pan-
 creas, and is remarkable for  the tenuity and extensibility
 of its coats.  The  splenic vein  is destitute of  valves, and
 empties into the vena portarum.  The spleen has also lym-
 phatic vessels; and  is furnished with nerves from the solar
 plexus.

   Of the Intimate Structure of the Spleen.—The  Sple-
 nic artery having penetrated into this organ, is divided and
 subdivided into a radiating succession of very fine branches,
 which according to  the injections of Ruysch do not anasto-
 mose with each other;  in consequence of which, one part
is sometimes finely  injected and not  another, of which, in
my own observations, I have had an example.   The veins,
on the  contrary, do anastomose, not  only as regards the
collateral branches of the  same primitive trunk, but also by
the collateral branches of' different trunks.  These anasto-
moses are not large.  The arteries terminate freely in the
veins, as may be proved by fine  injections, and by the mi-
croscope. ^
  The mass of the  spleen, upon superficial examination,
seems to consist  in  a dark brown pulp, contained in the
 cells dividing the cavity of the  internal coat, and may be 
THE SPLEEN.
59
easily demonstrated by tearing the spleen, and scraping it
with a knife handle.  MM. Assolont and Meckel believe,
that blood, besides being in the arteries and veins, is placed
in a state of particular combination  and of intimate  union
with the other organic elements of this viscus, and with a
large quantity of albumen; and that this combination of the
blood forms the dark brown pulp alluded to.  The great
quantity of albumen in the pulp, is readily proved  by the
hard coagulum which  it forms, when steeped in alcohol.
But a question has  arisen whether the pulp is extravasated
in the cells which contain it, or whether it is still retained
in the extremities of the blood vessels.   Superficial exami-
nation is in favour of the first, but M. Marjolin denies it on
the following  grounds; that injections cautiously made pass
immediately from the arteries to the veins; and that the
spleen,  when successfully injected and frozen, does not ex-
hibit ice in the interstices of its vessels, while their  capil-
lary ramifications, distended  by the injected  fluid, are dis-
tinctly seen.   From these he concludes that the glandular
structure of the spleen is formed essentially of arterial and
venous  capillary vessels with very delicate and extensible
coats, and  that they communicate with one another without
the intermedium of any cell; that the extreme tenuity of
these vessels,  and their extensibility in every direction, are
sufficient  to  explain the augmentation  of volume  of the
spleen,  under certain circumstances, as well  as the promp-
titude of its diminution under others.

   In addition  to this pulp, many observers have met  in the
spleen with an abundance of rounded corpuscles, varying
in size from an almost imperceptible magnitude to a line or
more in diameter.*  They are of a gelatinous consistence,
soft, grayish, and semi-transparent, and either cluster toge-
ther,  or are widely separated.    By Malpighi they were
considered glandular, and  by Ruyscht as convoluted ves-

  * Malpighi, Ruysch, Hewson, Home, Dupuytren, Meckel, &c.
  f Epist. Anat. IV. 
GO
ORGANS OP DIGESTION.
 sels.  Professor Soemmering, from the following paragraph,
 seems to join in  the opinion of the latter:  " Qui nonnun-
 quam  occurrunt, acini vel glomeruli, microscopii ope ac-
 curatissime explorati nihil  sunt, nisi vasorum fasciculi, vel
 teretes penicilli aut cirri vasculosi."  According to the ob-
 servations of Sir Evd. Home, they swell considerably after
 an animal has finished drinking.
  The spleen,  from having no excretory duct,  and  conse-
 quently from our inability to ascertain whether it secretes,
 has its nature  and uses shrouded in mystery.   No  single
 theory concerning it has ever been generally adopted, for
 speculations have multiplied in proportion to the obscurity
 of the subject.  The idea however on the use of this body,
 which to me is most reasonable, is, that it acts a subsidiary
 part to the liver.   It would seem, indeed, as a general rule
 in regard to glandular structures and such other  highly vas-
 cular organs of the  body as have an intermittent function,
 that the blood  which is  sent to them during their state of
 activity, should be passed off during a different channel,
 while they are in a state of repose.   This  does a  double
 service, it prevents superfluous secretions, and it also keeps
 up the vascular equilibrium of the body, as there must be
 always in readiness a quantity of blood sufficient for  the
 supply of  any secretion  which  may be wanted for  the
time.
  This proposition  will derive some additional illustrations
 from the foetal state.  The kidneys being then inactive the
glandulae renales take off their blood, and thereby prevent
what would otherwise be  a very inconvenient secretion of
 urine;  again, the  lungs being also then inactive, the circu-
lation through them is proportionately reduced,  and  the su-
perabundant blood is circulated through the thymus  gland.
But as the full functions of the lungs and of the kidneys are
established upon  birth, and continue uninterrupted  during
life, their supplementary organs, the thymus  gland, and
 the  capsulae renales, are not wanted, and they wither away
 after the early period of infantile existence is passed.
  But in regard to  the liver, its  functions also suspended
 during foetal life, are of an intermittent kind throughout 
THE PANCREAS.                  65
life, the spleen may therefore be considered a vicarious or-
gan for it during the wh'ole period of existence, receiving
its blood during the continuation of uterine life, and, in the
intermission of action, during common life.   The spleen is
therefore an organ useful to the foetal and to the perfect state,
and we consequently never see it in the collapsed and dwin-
dled condition of the thymus and renal gland.
  The same reasoning which applies to the spleen will also
apply to the Thyroid Gland, for the latter may be consi-
dered as executing for the salivary glands, during foetal and
perfect existence,  what the spleen does for the liver.   For
it is ascertained, that the salivary glands are inactive during
foetal existence, have only an  intermittent  action during
perfect life, and therefore probably stand  in need of a sup-
plementary organ during their periods of inactivity.  .

              SECT. III.--OF THE PANCREAS.

  The Pancreas  (Pancreas) is  the largest of  the salivary
glands.  It is fixed in the lower back part of the epigastric
region, and  extends horizontally across the spine, being
separated  from it by the lesser muscle of the diaphragm. It
is connected to the spleen on the left;  at  its right extremi-
ty is surrounded  by the  curvature of the duodenum; is
bounded  in front  by the stomach, which conceals it; and
is placed between two laminae of the mesocolon.
  The pancreas is about six or seven inches long, two wide,
and  flattened before  and behind.  Its  figure would be re-
presented by  a parallellogram,  were it not that its right
extremity is enlarged considerably into  a  head or tuber,
to which Winslow gave  the name of the  Lesser Pancreas.
The anterior face of this  organ is turned obliquely upwards,
and  is covered  by the superior lamina of the  mesocolon.
The posterior face looks obliquely downwards, and  is in
contact with the  aorta,  the vena cava ascendens, the su-
perior  mesenteric vessels, and several nerves:  along the su-
perior  margin of this face exists a long superficial fossa, oc-
cupied by the splenic artery and vein.
  Vol. II.—9 
66
ORGANS OP DIGESTION.
    With the exception of the  loose covering given by the
 mesocolon,  the  pancreas has  no peritoneal  coat; neither
 has it an appropriate tunic, unless we  consider as such the
 lamina of condensed cellular membrane which envelops it,
 and sends in processes between its lobules, as in the case of
 the salivary glands in the neck.

    Of the Minute Structure of the Pancreas.—This body,
 like the other glands which discharge saliva, is of a light gray
 or pink colour.   It consists in lobules of various forms and
 sizes, united by an intermediate cellular tissue, and having
 their interstices occupied by numerous blood vessels. These
 lobules, by a slight maceration,  may be separated and re-
 solved into small granular masses, constituting integral por-
 tions of the gland.
   The  arteries of the  pancreas come principally from  the
 splenic, as it cruises along the superior margin.   The veins
 empty into the splenic, and thus finally into the vena por-
 tarum.   It is furnished with nerves from the solar plexus,
 and has lymphatics.
   The  excretory duct of this  gland (Ductus Wirsungii)
 arises, by very fine roots or tubes, from each of the  small
 granular masses.   These tubes coalesce into larger  ones,
 which run transversely  from  the periphery towards  the
 centre of the gland, inclining slightly, at the same time, to-
 wards the right.   These  secondary tubes finally discharge
 successively into a single one, which runs the whole length
 of  the  gland nearly in its middle.   The  single  tube, by
 these additions, enlarges continually from left  to right,
 being small where it begins at the splenic extremity of  the
pancreas, and about the size of a crow quill at the duodenal.
At the latter place it is joined by the duct of the lesser
pancreas, which is derived after the same rule as itself. The
pancreatic  duct, almost  immediately afterwards, empties
into the ductus communis choledochus, or runs at the side
of the latter, and makes a distinct  opening  near it into the
duodenum, at the posterior part of the second  curvature. 
BOOK V.
            OF THE URINARY ORGANS.

  The  Urinary Organs,  (Organa  Uropoietica,) being
destined to secrete and to convey the urine out of the body,
consist  in the Kidneys, the Renal Capsules, the Ureters,
the Bladder, and the Urethra.

                   Of the Kidneys.

  The Kidneys (Renes) are two glandular bodies, fixed one
on either side of the spine, for the secretion of urine. They
are in the back part of the lumbar regions, have their spinal
edges inclining very slightly forwards, and extend from the
upper margin of the eleventh dorsal to the lower margin of
the second lumbar vertebra; the right,  however, is ten or
twelve lines lower down than the left, owing to the thick pos-
terior margin of the right lobe of the liver, which presses it
downwards. The  kidneys are covered in front by the peri-
toneum and lumbar portions of the large intestine, but in
such a manner as to be separated from them by a thick sur-
rounding layer of fat; behind, they repose upon the lower
part of  the great diaphragm, upon the quadrati lumborum,
and upon the upper end of the psoae magni muscles.
  The kidney is a hard solid body, of  a brown colour; in
shape it is a compressed  ovoid, excavated on the margin
which it presents  to the spine, and bears a very strong re-
semblance to the common kidney bean.  Its flat surfaces pre-
sent forwards and backwards, and the broad end of the ovoid
is above.  Its periphery is smooth, so that one does not see
from an external examination the lobules or internal divi-
sions.   The  excavation  of  the kidney, called its fissure 
lib
URINARY ORGANS.
 (hilum renale) occupies about one-third of its long diameter,
 is bevelled in front,  and leads to the very interior of the
 gland; conducting  its blood vessels and  excretory duct,
 which have to pass through  a quantity of cellular and adi-
 pose matter.  The  kidneys are generally of equal size, being
 about four inches long, and two wide; and each one weighs
 three or  four ounces.   They have no ligaments for keeping
 them in  position, but depend for the latter upon the adja-
 cent cellular adhesions and blood vessels.
   The kidney being destitute of a peritoneal coat, has a well
 marked capsule  which envelops it entirely and penetrates
 into its fissure for  some depth, where it is perforated with
 foramina for transmitting the blood vessels  and the ureter.
 This capsule is white, semi-transparent, fibrous, strong, and
 elastic: it adheres to the surface of the kidney by delicate
 cellular and vascular filaments, which are so weak that they
 permit it to be stripped off without difficulty,  and when so
 removed, some remains of the original lobulated  condition
 of the organ are manifested.
   The kidney receives from the aorta one or more branches,
 called  the renal  or  emulgent arteries; they divide  as they
 approach the fissure, and having  got into  the substance of
 the gland are distributed by innumerable  twigs to all parts
 of it.  Some  terminate in veins, others  in the  substance
 of the organ,  and  others, again,  in the  excretory tubes.
 The veins equal in  number the arteries, and are somewhat
 larger.  When both, or even  one, of these systems of blood
 vessels is  injected with wax and corroded, its branches are
 so abundant as to maintain the form of the  gland.   In en-
gaging in the fissure of the kidney, the arterial ramifications
 are in front, the  veins in the middle,  and the commence-
ment of the ureter  behind.*  The artery  on the  right side
is  longer than that on  the left.   The reverse is the case
with the  emulgent veins, as they empty into the vena cava
ascendens.   This arrangement is owing to the relative po-
sition of  the aorta and the vena cava ascendens, as the first
is  on the left side  of the spine  and the  last  on the right
side.
* This rule is subject to frequent variations. 
THE KIDNEYS.                   69
  The nerves  come  from the solar plexus of the sympa-
thetic, and adhering  to  the arteries cannot be traced very
far through the glandular structure.  The quantity of lym-
phatics is considerable.

  Of the Minute Structure of the  Kidney.—When the
kidney is cut open longitudinally, it obviously consists  of
two kinds of substance, differing in their situations, colour,
consistence and texture.   The one nearest to the periphery
of the gland is called from its position Cortical (Substantia
Corticalis,  Glandulosa) while the other, being  more in-
ternal, is designated  as  the Medullary or Tubular (Sub-
stantia Medullaris; Tubulosa; Fibrosa.)

  The Cortical or Secretory Substance forms the whole
circumference of the kidney, and, on an average, is about
two lines in thickness; butf it is thicker  at some points,  as
from its interior face processes converge towards the centre
of the gland, which separate the tubular  part into  as many
distinct portions of a conoidal shape.   It is composed prin-
cipally of arteries and veins ramifying among small grani-
form  corpuscles, that  secrete the  urine, and  are very dis-
tinct when viewed with a microscope.  It tears with facili-
ty, thereby presenting this granular appearance, and is of a
dark, or reddish brown colour, varying considerably, how-
ever, according to the cause of death.

  The granular corpuscles which form the mass of the cor-
tical or  Secretory  substance, are  individually imperfectly
visible to the naked  eye, and appear like rounded points.
The celebrated Ruysch, who was distinguished for the suc-
cess of his injections, and for the acuteness of his vision,
declared that they consisted wholly in the very fine extre-
mities of arteries  and veins having a penicillous  arrange-
ment;  while Malpighi  and Schumlansky viewed  them  as
purses or small sacs  of a  glandular character specifically
suited to  secrete urine, and upon  whose parietes the blood
vessels  ramified.  From these granuli the incipient extre-
mities of the tubuli uriniferi take their rise. 
70
URINARY ORGANS.
   The Tubular or Conoidal portion, consists in from twelve
to eighteen conoidal fasciculi  (Pyramides  Malpighianse)
presenting their rounded bases towards the  cortical matter,
and enclosed in it, while their apices  converge to the cen-
tral cavity of the kidney, the surface of which  they form.
The bodies  of these pyramids, as just mentioned,  are se-
parated by processes of the cortical matter;  but their apices
are free, and project from the internal surface  of the kid-
ney so as to resemble as many small nipples,  whence they
are called Papillae Renales.   Frequently two of the pyra-
mids coalesce so as to form but one papilla together; in such
case the latter generally preserves a duplicate appearance.
The papillae are arranged into three vertical rows, one be-
fore, one in  the  middle, and another behind; those of the
foremost row are turned backwards; those of  the middle
look inwards; and those behind look forwards.  Not un-
frequently there  is a  small  depression (foveola) on  the
very summit of the papilla.   The tubular part is of a lighter
colour and harder than the cortical, but the  difference in
these respects is not always very manifest.
   The conoidal fasciculi may each be considered, along with
its appertaining cortex, as a sort of distinct gland, or at least
as a lobe; for upon them depend  the lobulated  appearance
of the kidneys of a foetus, and of animals.   Each cone,
when analyzed, is found to consist in  a collection of tubes
(Ductus Uriniferi Bellini) converging from the circum-
ference of the kidney to the  apex of  the papilla.   These
tubes are more numerous  near the base in  consequence of
their successive junction in approaching the  apex:* their
terminating  orifices, on the latter,  appear like small pores,
from which  the urine can be squeezed in little drops.
   In the  early part  of the course of  the ductus uriniferi,
while they are still in the cortical matter, they are  wound
up in a very serpentine and tortuous manner, and are distin-
guished by the name of cortical canals, or ductus Ferrenii.t
They commonly go alone, winding their  way in the corti-

  * Schumlansky, Dis. de Struct. Renum, Strasburg, 1788.
  f A. Ferrein; sur la Structure des reins et du foie, Mem. de Paris, 1749. 
THE KIDNEYS.
71
cal substance until they reach its  most interior face, they
then  become straight, form the medullary substance, and
have  the name of the conduits of Bellini.*
   Some of the calculations on this  subject are not a little
curious.  It was ascertained by Ferrein that in each of the
conoidal fasciculi (Pyramides Malpighianae) there were,
at least, seven hundred subordinate cones or pyramids; and
as the number of cones is generally about fifteen, these py-
ramids  would amount to ten thousand five hundred.  Again,
each of the subordinate pyramids (Pyramides Ferrenii)  is
composed of many hundred uriniferous tubes, and, by the
observations  of Eysenhardt,t each of these tubes consists of
twenty smaller ones.
   The  arteries  of  the  kidneys  in ramifying,  minutely
through its structure, adopt the  following  arrangement.
They first of all pass through  the processes sent inwards
from  the cortical matter  between  the large cones, and,
having  got into  the  cortical matter,  they divide  into very
fine twigs, which form arcades around the bases of the py-
ramids of Ferrein, and pass between  them. J  These arcades
have  but few   anastomoses  with each  other,  and  their
branches go  almost  exclusively to the cortical  substance,
very  few of them  being  found  on the  tubular.   Their
branches radiate from the convexities of the arches, so as to
surround the base of each cone, and  to penetrate to the sur-
face of the kidney.   Some of these  branches terminate  in
corresponding veins, and others on the granular corpuscles.
The connexion between the corpuscles and the arteries, has
been  compared  to that  between  grapes and the stems on
which they grow, so as  to  form a  bunch.   A similar con-
nexion  of the  corpuscles with the  veins is not quite evi-
dent,  and even,  if it does exist, remains yet to be proved.
In one instance, I found in a young female subject one of
the kidneys in the pelvis in front of the rectum.  A similar
case has been seen by Professor Hensinger;§ and I have met

  *  L. Bellini, de Structura Renum. Florence, 1662.
  f  De Struct. Renum. Obs. Micros. Berlin, 1818.    * Schumlansky.
  § Am."Med. Jour. Vol.  iii. p. 442, 
72
URINARY ORGANS.
 with two instances of a coalition across the spine, of the two
 kidneys, so as to present the appearance of a bilobed organ.

   Of the Excretory Duct of the Kidney or the  Ureter.

   The Ureter is a canal  which conveys the urine from the
 kidney to the bladder.  It commences in the centre of the
 kidney by an  enlargement  called pelvis,  which branches  off
 into three or four  portions, (calices) one above, one below,
 and one or two intermediate.   Each of  these  calices is  di-
 vided, at its free extremity, into three or four short funnel-
 shaped terminations (Infundibula.)   Each of these termina-
 tions embraces  by its expanded orifice, the base of a pa-
 pilla, so  as to permit the latter to project into it, and thereby
 to distil its urine there.   Very frequently the number of pa-
 pillae exceeds  that of the infundibula, in which case two of
 the former project into one of the latter.
   The pelvis of the kidney having emerged at the fissure be-
 hind the vessels, from beingexpanded and somewhat conoidal
 in shape is reduced to a  cylindrical  canal, which, properly
 speaking, is the ureter: the latter is about the size of a goose-
 quill, and descends through the lumbar region, between the
 peritoneum, and the psoas magnus muscle.   It dips into the
 pelvis by crossing  in front  of the primitive iliac vessels and
 the internal iliac, crosses the vas deferens at  the back of the
 bladder,  and  penetrating obliquely the coats of the latter,
 terminates in an orifice ten or twelve lines behind that of the
 neck of the bladder.
   The excretory duct of the kidney is formed by two coats.
 The external is a condensed, fibrous, and cellular tissue, but
 is  destitute of any thing like muscle.   The internal is a thin
mucous lamina, which can  be raised  up without much diffi-
 culty, and is continuous,  at its lower end, with  the internal
 coat of the bladder; at the upper end, it is supposed by
 some anatomists to be reflected over the papillae, and even  to
pass for some distance into  the tubuli uriniferi.   This duct
has considerable powers of  extension, as  manifested by its
 transmitting large  calculi  from the kidney,  and also by it<= 
THE RENAL CAPSULES.
73
 general enlargement in some cases of obstructed urethra; its
 sensibility is exquisite when irritated by a calculus passing
 down it.
                 Of the Renal Capsules.
   The Renal Capsules (Capsulas Renales, Renes Succentu.
 riati,) are two small bodies, one on either side, placed upon
 the upper end  of the kidney.   They are of a yellowish
 brown colour tinged with red, have  no excretory ducts, and
 are more distinctly developed and softer in the perfect foetus
 than in the adult; whence they are ranked among those or-
 gans, as the thymus gland, and so on, which, having some
 peculiar value  in foetal existence, are perhaps unnecessary
 to that of the adult. *   They are of a triangular  pyramidal
 shape, flattened before and  behind, and rest by a  concave
 base upon the kidney; they are about fifteen lines high and
 as many wide.
   They are surrounded by a proper coat of lamellated con-
 densed cellular tissue, which by detaching inwards its pro-
 longations,  keeps the parts of these  bodies together,  and
 marks out their divisions.  In the centre of the renal cap-
 sule, a cavity may, from time to time, be found; but, accord-
 ing to my own observations, nothing is less certain than its
 existence; and, in the opinion of Meckel, when found, it is
 the result of cadaverous decomposition.  In the foetus it con-
 tains a reddish viscid fluid, which seems to consist in a large
 share of albumen, as it coagulates with alcohol; in children
 this fluid becomes yellow; in adults it is dark brown; and in
 old people it is either entirely deficient, or in a remarkably
 small quantity.

   Of the Minute Structure of the Capsulse Renales. The
 arteries of these bodies come from the emulgents, from  the
phrenics; and from the aorta. The veins of the right one ter-
minate in the cava ascendens, and of the left in the emulgent.
Each one is divisible into lobes, and  by a slight maceration
may be reduced  into lobules and small granulations.  The

  * This opinion has recently been confirmed in a dissection of a foetus,
by myself, where the kidneys being absent the capsulse renales existed
   Vol. II.—10 
74
URINARY ORGANS.
external part is rather more consistent and yellow than the
internal.   The granulations seem to have an intimate con-
nexion with the veins, as they are easily penetrated by fluid
injections from the latter.
  Reputed excretory ducts for these bodies have been found
going to the testicles,  to the pelvis of the kidneys, and to
the thoracic duct, but no  weight is now attached to such
assertions.

                    Of the Bladder.
  The Bladder, (Vesica  Urinaria,) the reservoir for the
 urine, is placed in'the pelvis, just behind the symphysis of
the pubes.   When pressed upon, as it commonly is, by the
adjacent viscera, it is flattened somewhat before and behind;
but, removed from the body and inflated, it is an elongated
sphere or oval; the greatest diameter of which is vertical, in
regard to the linea ilio-pectinea.  The superior end of the
bladder is called the upper fundus, and the lower end the infe-
rior fundus; the latter is rather more obtuse  than the other;
and between the two is the body.  The neck of the bladder
is its place of junction with the urethra.  The form of the
bladder is influenced by age and by sex; in  very  young in-
fants it is cylindroid,  and, owing to the smallness of the
 pelvis,  rises up almost wholly into  the abdomen.  In the
 adult woman, who has frequently born children, it is nearly
 spherical, has its greatest diameter transverse,* and is more
 capacious than in man.
   The bladder is bounded in front by the pubes,  above by
 the small intestine, behind by the rectum, and below by the
 prostate gland and the vesiculae seminales.   From its supe-
 rior end there proceeds to the umbilicus a long conical liga-
 ment, the urachus, which is placed between the linea alba
 and  the peritoneum, and produces a slight elevation or
 doubling of the  latter.   In mankind the urachus is solid;
 some very rare cases, however, are reported in which it has
 been hollow, so  as to permit the urine to flow through it
 from the bladder.  This vicious conformation has generally
 been attended with a congenital obstruction of the urethra, t
   * H. Cloquet, Anat. Descrip.      f Sabatier, Anat. vol. iii. p. 19. 
THE BLADDER.
75
When the anterior  parietes of the abdomen  are put  upon
the stretch, a semilunar fold of the peritoneum is  seen to
proceed, on either side of the urachus, from the lateral sur-
face of the bladder almost to  the umbilicus.   These folds
contain, in their loose edge, the fibrous remains of the um-
bilical arteries of the foetus, called, subsequently to uterine
life, the Round Ligaments of the  bladder, though they have
little or no influence on its position.   The bladder is also
fixed in its situation by the pelvic aponeurosis, a membrane
elsewhere described with  the organs of generation.

  The bladder consists of four coats: the Peritoneal, the
Muscular, the Cellular, and the Mucous.
  The Peritoneal  Coat is very imperfect, and is  derived
from  the part of the peritoneum which descends from the
anterior parietes of the abdomen into the pelvis.  It covers
the upper and the posterior face of the bladder, and then
passes to the  rectum, by sinking  down between these two
organs,  so as  to form the small pouch beneath the lower fun-
dus of the bladder; the apex of  this  pouch reaches within
an inch of the base of the prostate.  The upper margin of
this pouch next to the bladder  forms a strong horizontal
doubling, stretching across the pelvis, when the rectum is
empty, and is on a level with the posterior end of the vesi-
culae seminales.  Being connected to the subjacent muscular
coat by a thin lamina of loose cellular membrane, the peri-
toneum may be dissected off without difficulty. In consider-
able distentions of the  bladder, it is reflected from  the up-
per end of the latter to the  abdominal  muscles in a line
much above the pubes,  whereby a good  opportunity  is af-
forded of reaching, with  an instrument, the cavity of the
bladder without injuring the peritoneum.
  The Muscular Coat is of a thickness intermediate to that
of the stomach and of the  oesophagus,  and its fibres are pale.
They pass in very varied directions,*  and are collected into
flattened fasciculi, leaving  interstices between them, through
which the internal coat is  occasionally caused to protrude,
in strictures and other  obstructions of the urethra.  These
• Santorini; Septemd. Tabul. 
76
URINAKF ORGANS.
fasciculi, for the most part, arise about the neck of the blad-
der, and ascending upwards, before, behind, and laterally,
terminate at the superior fundus in the base of the urachus.
Within these, which may be considered as the longitudinal
fibres of the bladder,  there are others forming a thinner la-
mina, whose course is transverse, or oblique, they serve to
connect the preceding.   As the muscular fibres are collect-
ed at the neck of the  bladder, and at the urachus, there is,
of course, an increased thickness at these points.
  The Cellular Coat consists in a close,  dense, lamellated,
and fibrous tissue, very extensible and difficult to tear.   It
is impervious to water, adheres closely to the muscular coat
without and to the mucous within,  so as to  form a strong
bond of union between them.  It is pervaded by many ves-
sels and nerves, which it conveys to the mucous coat.
  The Mucous Coat is also  called the villous, but is much
more smooth than the corresponding one of the stomach.
It is white with a slight tinge of red, and abounds with mu-
cous follicles, which,  though small and scarcely discernible
in a natural state, are  rendered very obvious by disease.  It
stretches with much facility, but, like other mucous mem-
branes, does not restore itself readily, and is rather thrown,
in the contracted state of the bladder,  into wrinkles or folds
having a diversified course, and of a fugitive character, as they
disappear again upon the next distention. It is very vascular.
  The internal  face of this  coat presents, at  its inferior
part, the following appearances:
  1. The Vesical Triangle (Trigonus Lieut audi, Trigone
Vesicate) is placed immediately behind and below the neck
of the bladder, occupying the space between it and the ori-
fices of the ureters.   It is an equilateral triangle of an inch
in length, its surface is smooth, is not affected materially in
extent either by the  dilatation  or  the  contraction  of the
bladder, and is elevated so as to be sufficiently distinct and
well defined.
  2. The anterior angle of the triangle looks into the ori-
fice of the urethra, and  is generally so elevated that it has
obtained the name of  Uvula Vesicae; it is, however, simply
a projection of the mucous membrane depending upon the 
THE BLADDER.
77
subjacent third lobe of the prostate; which, at this point, is
not unfrequently much enlarged in the aged, and then pre-
sents a great difficulty in the introduction of a catheter.
  3. The Orifices of  the  ureters form the posterior angles
of the triangle, and are contracted somewhat below the size
of the canals  themselves.   They are said, by Mr. Charles
Bell,* to be furnished each  one with  a small fasciculus of
muscular fibres, which runs backwards  from the orifice of
the urethra, just beneath the lateral margins of the triangle,
and, in its contraction, will stretch the orifice of the ureter
so as to permit an easy passage of the urine into the blad-
der.  The retrogradation of the urine is prevented by the
ureter passing obliquely,  for six or eight lines, between the
muscular  and mucous coat;  there  is something also in the
obliquity  of the orifice itself which assists in this effect; as
I have ascertained by removing the muscular coat entirely,
at this point, and dissecting up the ureter, notwithstanding
which, the bladder,  when inflated, still retained its con-
tents.   Where the ureter penetrates the muscular coat,  I
have in several instances  found a layer of longitudinal mus-
cular fibres enveloping it for half an inch, or an inch.
   4.  The Inferior Fundus of the bladder (bas-fond of the
French) is a depression  of the general concavity of the
bladder, of about six lines  in depth, placed  between the
base of the triangle and  the posterior side of the bladder.
In the erect position,  calculus, when one has it, lodges there.
   5.  The Internal Orifice of  the  neck of the bladder,  re-
sembles strongly that of  a Florence flask,  modified,  how-
ever, by the projection of the uvula vesicas,  which makes
it somewhat crescentic below.  The neck of the bladder pe-
netrates the prostate  gland,  but, at its  commencement,  is
surrounded by loose  cellular tissue containing a very large
and abundant plexus  of veins, t  The internal layer of mus-
cular fibres is here transverse;  and they cross and intermix
with each other in different directions, forming a close com-
pact tissue, which has the effect of a particular apparatus for

  * Med. Chir. Trans.  Vol. III.
  f Mascagni, Anat. Univers. Str. prim. tab. spec. Fig. V. 
78
URINARY ORGANS.
retaining the urine, and  is called  Musculus Sphincter Ve-
sicae Urinaria;.   Generally, anatomists have not considered
this  structure as distinct from the muscular coat at large,
but Mr. Charles Bell, of London, whose reputation as an
anatomist is well established, gives the following account
of it: "Begin the dissection by taking off the  inner mem-
brane of the bladder from around the orifice of the urethra.
A set of fibres will be discovered on the lower half of the
orifice,  which being carefully dissected, will  be found to
run in a semicircular form round the urethra.  These fibres
make a  band  of about half an inch in breadth, particularly
strong on  the  lower part of  the opening, and,  having
mounted a little above the orifice on each side, they dispose
of a portion of their fibres in the substance of the bladder.  A
smaller  and somewhat weaker set of fibres will be seen to
complete their course, surrounding the orifice on the upper
part; to these sphincter fibres  a bridle is joined, which
comes from the union of the  muscles of the ureters."*
That a power exists in the neck  of the bladder of retaining
completely the  urine, has been  satisfactorily demonstrated
to me in a case  of  fistula in  perineo, which was presented
to the notice  of Dr. Physick and myself, a few years ago.t
Occasionally  there exists on each side of the  neck of the
bladder, passing from it to the  pubes, a muscle of half an
inch in breadth, the effect of which is, to draw the neck of
the bladder towards the symphysis pubis.
   As the urethra of the male performs the double office
of conducting both semen and urine,  it will be  described
more properly along with the organs of generation.
   The Urine has a considerable number of constituents, the
proportion of which varies  according  to  age,  health, and
other circumstances.   Water forms about nine-tenths of
it, the  remainder  is  an  animal matter insoluble in  alco-
hol;  uric  and lactic acids; lactate of ammonia; sulphate of
potash and of soda; hydrochlorate of soda and of ammonia;
phosphate of soda and of lime; fluate of lime.

  * Diseases of the Urethra, &c. p.  10. Lond. 1820.
  | Chapman's Med. and Phys. Journal, 1824. 
BOOK  VI.
                 Organs of Generation.


                     CHAPTER  I.

     OF THE ORGANS OF GENERATION IN THE MALE.

   The Male Organs of Generation  consist in the Testicles
and in the Penis, with their appendages; or, in the language
of some anatomists, in the Formative and in the Copulative
Organs; which distinction has been applied to both sexes.

                SECT. I.--OP THE PENIS.

  The Penis (Membrum Virile, Mentula) from perform-
ing two offices; one of which is the conducting of urine from
the bladder, and the other the projection of semen into the
female; has accordingly a  peculiarity of structure, which
allows it to assume a state of rigid distention or of collapse,
according  to the exigencies of the system.   Its shape is al-
most cylindrical, but terminating in front by an obtusely
pointed extremity.  It adheres by its posterior end or root
to the bones of the pelvis, at and below the symphysis
pubis.
  It is formed by common integuments, by cellular tissue,
by the Corpus Cavernosum, and by the Corpus Spongiosum!

  The skin on the penis is more thin and delicate than it is
on most other parts of the  body, and is furnished with  a
considerable number of sebaceous follicles or glands about
the root of the organ, with  hairs growing from the centre
of them.  This same skin, in passing to the abdomen over 
80
ORGANS OF GENERATION.
 the pubes, is  somewhat protruded by a subjacent deposite
 of fat and cellular matter,  causing an appearance corres-
 ponding with the mons veneris of the female; and is also
 generally thickly covered with short curly hair, which, as
 the individual advances in life, proceeds in a pointed direc-
 tion to the umbilicus.  The skin of the penis is but loosely
 connected to the organ, so that it slides readily backwards
 and forwards, and by its elasticity is well suited to the va-
 rying states of erection and collapse.   At the anterior ex-
 tremity it is thrown into a duplicature or fold, the Prepuce,
 (Preputium,) the internal lamina of which being inserted
 circularly into the penis, some distance back from  the point,
 permits a considerable portion of the extremity of the penis,
 called the Glans, to remain uncovered when the prepuce is
 drawn back.   The under middle part of the prepuce is at-
 tached to the extremity of the  glans by a vertical  longitudi-
 nal duplicature,  called the  Fraenum,  which extends to the
 orifice of  the urethra.
  The skin does not actually stop at the  circumference of
 the glans, but is continued smoothly over it, modified how-
 ever so much in its structure, as to be much more adherent,
 soft, delicate,  vascular,  and  sentient; its  cuticle is a thin
 epithelium readily separated by maceration.  The project-
 ing circular and oblique shoulder of the glans, behind which
 the skin becomes firmly joined to the penis, is called Coro-
 na gland is.  The contracted portion  behind the corona is
 the neck (collum.)  On the surface  of the  neck and  the
 posterior face of the corona, the  skin is furnished with an
abundance of small glandular masses or follicles, (Glandulae
 Odoriferas Tysonii,)  which secrete the thick  white  seba-
ceous matter, (smegma prosputei,) that accumulates when
personal cleanliness is not attended to.

  The penis, in addition to other modes of attachment to
 the bones of the pelvis, is fixed by the Ligamentum Sus-
pensorium.  The latter is  a triangular vertical fibrous la-
 mina,  which proceeds  downwards from  the symphysis
 pubis to the dorsum of  the penis; and, according to Mr.
 Colles, envelops this organ to  the glans, forming its cellu- 
THE PENIS.
81
lar coat, .and being continued into the fascia superficialis ab-
dominis.  Posteriorly it is  lost insensibly on the fascia of
the thighs, covering the adductor muscles.  At its origin it
is occasionally furnished with muscular fibres; one strongly
marked instance of which has been presented to me in my
own dissections.

  The Corpus Cavernosum of the penis,  forms by much
the most considerable portion of the whole organ.  Exter-
nally it is a white fibrous membrane, of a dense  structure,
enjoying extensibility and  an extreme degree of  contracti-
lity.   Its fibres pass for  the most part longitudinally, ex-
cept about the root, where they are blended with the peri-
osteum of the bone, and with  the tendons of  the muscles.
This coat of  the penis is occasionally called its elastic liga-
ment.  It arises  by two  conical  crura, from the inter-
nal face of the crura of the pubes  and ischia to within a
little distance of the  anterior part of the tuber ischii.   At
the lower part of the symphysis pubis these crura join and
form a body; which, when stripped  of  its  connexions,
resembles two cylinders lying along  side of  each other,
united; and which terminate  in common anteriorly, by a
truncated cone, covered obliquely by the glans.  At the
posterior  part of the corpus cavernosum, in its centre, there
is a septum, almost complete, also  of the same elastic sub-
stance, which separates the  two halves from each other; but
anteriorly this septum is more imperfect, having an arrange-
ment like the  teeth of a comb, whence the  term  Septum
Pectiniforme has been given it.
   In the middle of the corpus cavernosum above is a lon-
gitudinal depression for lodging the veins of the penis, and
in the same manner there is another below, for the corpus
spongiosum urethrae.   The cavity of this membrane is filled
by a spongy  tissue, that arises from its internal face, and is
formed of filaments and little laminae; they, by crossing each
other, make  a multitude of cells, which have a perfectly
free  communication  with  one another, and generally  are
somewhat occupied by blood.  A fine injection through the
   Vol. II.—11 
82
ORGANS OF FENERATION.
artery of the corpus cavernosum will fill these cells and re-
turn through the veins;' from which cause the cells may be
considered as intermediate to the two orders of vessels.

   The Corpus  Spongiosum  Urethrae extends  from ten or
twelve lines behind the junction of the crura of the corpus
cavernosum, to the anterior extremity of the  penis.   Ex-
ternally  it has  a  coat resembling that of the corpus caver-
nosum, except  that it is thinner, and in its centre is the ca-
nal for the passage of urine.   Between the canal and the
coat is a  spongy structure, much finer than that of the cor-
pus cavernosum,  and though  the cells communicate freely,
still they have the appearance of convoluted veins.   The
corpus spongiosum is not of equal diameter  in  its whole
course, for its commencement in the perineum, where it is
pendulous, is enlarged into what is termed a Bulb;  from
this it diminishes gradually to the anterior end, where it is
again enlarged  into the glans penis.
   The Urethra is a canal, whose length varies according to
the degree of erection in the penis, and extends from the
neck of the bladder to the extremity of the glans.  It has
several curvatures, and  receives in its course the ductus
ejaculatorii, the  excretory ducts of Couper's glands, and
the mucous lacunae of its own  internal membrane.   The
first part of this canal which traverses the prostate gland is
from fifteen to  eighteen  lines in length,  and is called the
Prostatic Portion; it  is well supported by this body, al-
though its own  sides are very thin.  On its inferior surface
is  a doubling which constitutes the Verumontanum or Ca-
put Gallinaginis.   On either side of the caput gallinaginis
the canal of the urethra is depressed into something like a
cul-de-sac, where are to be found the lacunae of the prostate
gland.
  Between the  Prostate and the Bulb is the Membranous
part of the urethra, about eight or ten lines long; it is un-
protected, except by a soft covering, which seems in some
measure to be a mixture of gelatinous matter and muscular
fibre.   The  former was considered by Littre as a glandular 
THE PENIS.
83
body which secreted a viscid humour into the interior of
the canal; the latter probably is the part described by Win-
slow as the inferior prostatic muscle; which, arising on each
side of the membranous canal, goes to be inserted into the
corresponding  branch of the pubes  near the symphysis.
The membranous part of the urethra does not get into the
end of the bulb, but penetrates it from above, half an inch
or  more occasionally, from its extremity, just below the
junction of the Corpora Cavernosa.
  The canal varies in its dimensions;  at its commencement,
which is synonymous with  the neck of the bladder, it is
large: it then contracts at the back of the caput gallinaginis,
and immediately enlarges in the fore part of the prostate.
The membranous part is small;  the canal then  enlarges in
the bulb.  In the body of the penis the canal is successive-
ly diminished, till it comes almost to the glans, when it is
so remarkably enlarged again  as to get the name of Fossa
Navicularis; it terminates finally by a short vertical slit at
the extremity of the glans.
  In the whole length of the canal there are two whitish
middle lines, one above, and the other  below;  and  in the
membranous and spongy portions, excepting the fossa na-
vicularis, longitudinal folds of the lining membrane exist,
which are effaced by distention.  In the upper part of the
canal there are a great many mucous lacunae;* Loder has
marked about sixty-five; there  is one particularly large in
the upper surface of the fossa navicularis, which, it is said,
has stopped the point of a bougie and been  mistaken for
stricture, f
  Mr. Shaw has described a set of vessels immediately on
the outside of 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  mem-

  * Tabula Anat.
  f Sir Everard Home  has lately communicated to the Royal Society  a
highly interesting paper on the structure of the lining membrane of the
urethra. From his microscopial observations he is induced to think that
it is muscular. 
S4
ORGANS OF GENERATION.
branous part of the urethra, and forms even a small bulb
there.*  His preparation, being a quicksilver injection of the
part,  is certainly a very satisfactory demonstration of its
existence, yet,  in my own observations, where  the blow-
pipe has been resorted to, it has rather appeared to me to
be the cellular  membrane connecting the canal of the ure-
thra with the corpus spongiosum.
  The arteries  of the penis come from the internal pudic;
some of its veins follow the  course of the arteries,  and
others collect into the vena magna ipsius penis; the nerves
come from the  internal and external pudics.

   SECT. II.--OF THE  MUCOUS  GLANDS AND APPARATUS.
  The Seminal Vesicles (Vesiculse Seminales) are two con-
voluted tubes, one on each side, two inches in length; placed
on the lower fundus of the bladder, between it and the rectum
and behind the prostate gland.  At their anterior extremities
they approach very nearly to each other, being only separa-
ted by the intervention of thevasa deferentia. They are fixed
to the bladder, and surrounded by a thick mass  of  adipose
and  cellular matter, with many blood vessels, principally
veins, passing through it.
   When inflated and  dried, they present the semblance of
cells, but are in fact, long tubes; which, by being convoluted,
are reduced to  the apparent dimensions mentioned.   When
dissected and stretched out, they are four or five inches long
by three lines in diameter.
   There are also several pouches on each side of the long
tube which increase the number of cells. The convolutions
are preserved by the  intermediate cellular tissue.   These
bodies  consist  of two  coats: an external, which is  fibrous
and cellular; and an internal, which is mucous, being a con-
tinuation  of lining membrane of the urethra.   They are
commonly filled by a drab-coloured thick fluid, supposed to
be a mixture of the semen, with their own proper secretion
though, of this, Mr. Hunter doubted, t  The excretory duct

  * Med. Chir. Trans, vol. x.
  | Observations on the Animal CEconomy. 
                    MUCOUS GLANDS.                   85

of each vesicle is about a line and a half long, when it joins
in the subtance of the prostate with the vas deferens of the
same side; a common  canal (Ductus Ejaculatorius) is thus
formed, which runs parallel with its fellow, below the  ure-
thra.*

   The Ductus Ejaculatorius is about eight or ten lines long,
and opens by an oblong  orifice, at the lateral anterior face
of the Caput Gallinaginis:  it is larger behind than before,
which gives it a conical shape,  and allows fluids injected to
pass freely from  the vas deferens to the vesicula, and the re-
verse.

   The Prostate  Gland (Glandula Parastata\)  is a body
about the size and form of a  horse chestnut, fixed on the
neck of the bladder, and penetrated by the urethra, which
traverses it much nearer its superior than its inferior  sur-
face.  The  base of it is turned backwards,  and the point
forwards; its inferior surface rests upon the rectum, and its
sides, in  the distentions of this organ by faeces,  are over-
lapped by it.  The Prostate has, posteriorly,  a notch in its
centre, which divides it  into two lateral lobes, and by rais-
ing the Vesiculae Seminales, we see where their excretory
ducts penetrate the gland, and separate from  the body of it
the little tubercle, to which Sir Everard Homef has parti-
cularly called the attention of the profession, and considered
as a Third  Lebe, it being certain  that it is frequently the
seat of disease and tumefaction.
   On the under surface of the canal formed in the prostate,
by the urethra, is the oblong elevation called the Verumonta-
num, or Caput Gallinaginis.  It commences a little in front
of the uvula vesicae, and, being broader and higher behind,
comes to a point very gradually before; it is about eight or

  * Lately, in a dissection executed at the university by Dr. Togno, a mus-
cle was found on the inferior surface of the seminal vesicles arising from the
prostate gland, and inserted into them.  This is said to be a common ar-
rangement in some animals
  tFrom ','$»,(«,,, sto.
  1 Diseases of Prostate. 
8G .
ORGANS OP GENERATION.
ten lines long. Along the posterior part of this ridge is a long
cleft, being the orifice of a lacuna  first observed  by Mor-
gagni; and in front of it are the orifices, bordering upon each
other, of the ductus ejaculatorii.
   The prostate consists in a condensed, white, extensible,
though easily lacerated fibrous cellular tissue, within which
are placed a great number of mucous follicles, that have from
eight to twelve ducts, or, according to Loder, from  thirty-
two to forty-four, passing obliquely forwards, and  termi-
nating in the urethra, as stated, at each side of the urethral
crest,  or  caput gallinaginis.   The fluid secreted is thick,
ropy, white, and semitransparent,  in a healthy state.   The
prostate is  surrounded by a  fibrous capsule,  to  be de-
scribed.
   The lacunae of  the third  lobe penetrate the coats of the
bladder, behind the caput gallinaginis.

   Of the Glands of Couper.—These glands are also in-
tended for the secretion of mucus, or a fluid very much like
it, into the canal of the urethra. They are two in number,
one on each side, and are situated in advance of the pros-
tate, between the  laminae of the triangular ligament, at the
point where the bulb of the urethra adheres  to it.  Com-
monly they are about the  size of a garden pea, but not un-
frequently much  smaller, and in some instances, cannot be
found at all, which induced  Heister to declare, that he had
searched for them fruitlessly.  They are yellowish, hard,
and consist of several lobules united together.  Each one
has an excretory duct that  receives readily a bristle, and
passes obliquely forwards, between the corpus spongiosum
and the canal of the urethra, to terminate in an oblique ori-
fice in the latter, about an inch distant from the gland.
   One or more  glands, of the same description, are occa-
sionally found just in front of Couper's.   They also dis-
charge their secretion into the adjacent part of the urethra.
In my own dissections I have not met with them. 
THE TESTICLES.
87
             SECT. III.--OP THE TESTICLES.

   The Testicles (Testes, Didymi) are two in number, Qne
 on either side of the scrotum.  From being the seat of the
 secretion of sperm or the male prolific liquor, their function
 is of the first importance in  the  act of generation.  They
 are of an oblong oval form, somewhat compressed laterally;
 and present  their edges forwards and  backwards.   From
 being suspended near the middle of their posterior edge by
 the spermatic chord, the  upper end points somewhat for-
 wards, while the lower one is directed in the same degree
 backwards.  They are about an inch and a half long, by
 one inch in breadth,  and eight or nine lines in thickness.
 They are of equal size  generally, but in case of a difference
 it is in favour of the  right; the latter is also remarkable for
 being suspended higher than the left, a feature in ancient
 statuary so universal, as to prove  the vigilance and accuracy
 of the sculptors of those days, in regard to the proportions
 and peculiarities of the human form.
   The testicle is enveloped by several tunics; they are the
 scrotum, the dartos, the tunica vaginalis, and the tunica al-
 buginea.

   The Scrotum  is merely a continuation of the common
 skin from the inner  side of the thighs, the perineum, and
 the  penis, and is common to the two  testicles.   It is a
 symmetrical  bag, and the two halves are  marked off from
 each other by a middle line or elevation of the skin called
 the Raphe, which begins in the perineum at the anus, and,
 winding around the scrotum, is continued along the under
 surface of the penis to the prepuce.
   The skin of the scrotum is thin, darker  than elsewhere,
but has  a thick, strong epidermis;  it has  many sebaceous
follicles in it, and is  sparingly furnished with  hair.  It is
very extensible, as manifested in fatigue, and by hydrocele;
and may be contracted again so as to draw the testicles close
under the pubes, though for the latter power it principally
depends upon the  subjacent coat.  Its surface is covered 
88
ORGANS OP GENERATION.
with wrinkles, for the most  part transverse, and ending at
the raphe; they are  effaced during its  great distentions in
hernia and dropsy, and  then it has a smooth  shining sur-
face.

  The Dartos is placed within the scrotum, and forms two
distinct sacs or tunics, one for each testicle.  It arises from
the inferior margins of  the  crura of the ischia and of  the
pubes, and lines the scrotum  till it reaches the raphe;  it is
then reflected upwards  to  form the partition  between the
testicles,  (septum scroti,) and  terminates at the corpus
spongiosum urethrae.   This  membrane, according to  the
observations  of MM. Chaussier, Lobstein, and Breschet,*
does not exist in the scrotum till the descent of the testicle,
and then appears to  be  an expansion of the gubernaculum
testis.
  It receives a considerable number of blood vessels, which,
owing to the thinness of the skin, may  be seen  in the living
body ramifying through its substance: its  general appear-
ance is therefore reddish.  It is destitute of fat, and consists
in long fibres much  matted together, and passing  in every
direction: they are easily  separated by distention with  air
or water, and by slight  maceration.  Its powers of contrac-
tion are exceedingly well  marked upon the application of
cold to the scrotum, from which cause, it  has been consi-
dered  by many anatomists as muscular; the only distinct
evidences, however, which I have met with of a resemblance
to the latter, have been found generally on its posterior face,
near the perineum, t   From its equivocal character, J. F.
Meckel has very ingeniously suggested that it forms the tran-
sition from cellular to muscular tissue,  and that there exists
between it and other muscles the same relation that there
is between the muscles of the superior and of the inferior
orders of animals. Among the latter the fibrous structure is
indistinctly marked, and is masked by gelatine; an element
  * Dictionnaire des Sciences Med. tome VIII.
  f Since the first edition I have dissected one subject, (January, 1830,)
where the fibres were evidently muscular, though interwoven. 
THE TESTICLES.
89
of  the  cellular  tissue which envelops  and conceals  the
fibrine, an element of the muscular tissue.

  The fibres of the  cremaster muscle, which are next in
order, form a very imperfect covering to the testicle,  and
belong rather to the  spermatic chord: what remains to be
said concerning them will be  more  properly introduced
into the account  of the  latter.  The  cellular substance
that connects the dartos and the cremaster with the tunica
vaginalis forms  a  compact and  perfect lamina, sometimes
spoken  of  as the  Tunica Vaginalis Communis  Testis.
There is one for each testicle, which  it surrounds entirely,
as well  as its chord,  and connects the chord to the margins
of the abdominal rings as stated in the account of them.
At its upper end it is continuous with the cellular substance
that unites the peritoneum to the parietes of the abdomen, as
may be proved by inflating it, when the air will penetrate
accordingly through the abdominal canal.

   The Tunica  Vaginalis was  originally a process of pe-
ritoneum,  communicating with  the  cavity  of  the latter
through the  abdominal canal;  but, in the adult, it appears
as a complete and  distinct sac.   As it is very rigidly com-
parable to  a double night-cap drawn over the head^ we ac-
cordingly find that the testicle, along with the epididymis",
is pushed into it from behind.   That portion of the tunica
vaginalis which  is in contact with the testicle, or rather with
the tunica  albuginea, adheres  so closely that it  cannot be
separated except very partially, and in shreds;  but it may
be detached easily from the epididymis,  with the convolu-
tions of which  it  is in  immediate contact.  This sac is
longer and larger than the  testicle itself, from which cause
it ascends for several lines above the superior end of the
gland, and  the free part hangs loosely about it.   Its cavity
may, with  but little force, be injected so as to hold an ounce
or two of fluid.
  This  membrane is smooth  and polished on the surface
forming its cavity, and contains a small quantity of synovial
   Vol. II.—12* 
90
ORGANS OP GENERATION.
halitus, which allows the opposed surfaces to glide freely
upon one another.  Its  exterior connexion with the dartos
is  so  slight that it may be withdrawn without dissection,
with the exception of an adhesion at the lower end  of the
testis,  arising from the remains of the gubernaculum:  in
such case, however, it still continues to be invested by the
tunica vaginalis communis, from which it can only  be re-
moved by a special dissection.

  The Tunica Albuginea is the proper coat of the testicle,
is  in immediate contact with its  glandular structure, and
serves to  maintain its shape, as well  as to protect it from
pressure.   From its  internal surface  proceed many mem-
branous, horizontal  fibres,  which form  partial  partitions
of its  cavity and incline  towards its posterior part, where
they terminate in a longitudinal projection, called Corpus
Highmorianum.  The latter is of a prismatic  shape, some-
what broader  above than  below, and is but of little conse-
quence, except that it was once erroneously supposed to  be
a sinus into which the seminiferous tubes discharged.   The
albuginea is perforated by several foramina along its poste-
rior margin, where there is a deficiency of tunica vaginalis,
for the passing of excretory ducts and  blood vessels.
   This membrane is dense, strong, white, and fibrous, re-
sembling in structure the tunica sclerotica of the eye, and
the dura mater of the brain.

   Of the Minute Structure of the Testicle*—The glan-  •
dular portion of the testicles consists in a congeries of con-
voluted tubes  (Tubuli Seminiferi) amounting to 300, ac-
cording to Dr. Munro; and whose aggregate length is  5208
feet;  the  diameter of each  one does  not exceed one two-
hundredth part of an inch, and its length  is somewhat short
of seventeen  and a half feet.   These  tubes form convolu-
lutions or hanks, the threads of which are serpentine, very

   * Hunter, Med. Comment, p. 1, 1777.  Albinus, Acad. Annot. Lib. ii.
 Loder, Tab. Anat. Ruysch, Thes. Anat. iv. Haller, Op. Min. torn.  ii. Alcx-
 Munro, de Testibus, Ed.  1755. 
THE TESTICLES.
91
much like the thread of a ravelled stocking; and are held
together by a delicate cellular  substance easily softened by
maceration.   Each tube  forms of itself a hank  or lobule,
which is kept distinct from  the adjacent ones by the parti-
tions of the albuginea, and  may be easily picked out from
them.   Their extreme  tenuity  and delicacy  of  structure
cause them, when well  macerated, drawn  out with a pin,
and then  suspended in water, to resemble  a tangled skein
of fine silk.
  The tubuli seminiferi  finally terminate in straight tubes,
called the Vasa Recta, which unite near the centre of the
testicle, in a somewhat complicated arrangement,  obtaining
the name of  Rete Vasculosum  Testis.  From  the latter
there proceed from twelve to  eighteen  ducts (Vasa Effe-
rentia) which go upwards  and backwards  to penetrate the
corpus  highmorianum and  the tunica albuginea.   Each of
these vasa efferentia  is  then convoluted upon itself into a
conical body, called  Conus Vasculosus, which presents its
base  backwards.  Each cone at  its base  has its tube en-
tering successively into  the tube of which the Epididymis
is formed.
   Notwithstanding  the  extreme  tenuity of these  several
arrangements in the excretory ducts of the testicle, they
may  be  entirely filled with quicksilver from the  vas de-
ferens; but the task is one of great difficulty, and rarely suc-
 ceeds.
   The Epididymis is the prismatic  arch which rests verti-
cally on the back of the testicle, and adheres to it by the
reflection of the tunica vaginalis.   It is enlarged at both
ends, the upper of which being formed by the Coni Vascu-
losi,  is called the Globus Major, and the lower enlargement
 is the Globus Minor.   It is formed of  a single convoluted
 tube, of the fourth of a  line in diameter.    After this tube
 has got to the lower end of the globus minor it becomes less
 convoluted, enlarges, turns upwards on the  inner  side of
 the epididymis and obtains  the name of Vas Deferens.  Be-
 fore it reaches the top of the epididymis it has become per-
 fectly straight, or almost so.   There is a blind duct which 
02
ORGANS OF GENERATION.
begins at the top of the epididymis and terminates below:
the object of it is not understood.


               Of the Spermatic Chord.

  The Spermatic Chord is a fasciculus of about half an inch
in diameter, which may be felt very readily through the
skin of the scrotum, passing from the upper end of the tes-
ticle to the external abdominal ring.  It is formed by the
Vas deferens; the Spermatic Artery and Veins; the Lym-
phatics of the Testicle; and the  Nerves; all being covered
in by the Tunica Vaginalis Communis, and by the Cremas-
ter Muscle.

  The Cremaster Muscle, also  called the tunica elythroi-
des,* being derived from the internal oblique and the trans-
verse muscle of the abdoment  forms a very complete enve-
lope to the chord from  the abdominal ring to the testicle.
But when it reaches the latter its fibres spread  out and be-
come indistinct upon the tunica vaginalis communis, as  they
there consist in small, pale, scattered fasciculi, many of which
terminate insensibly, while others form on the front of the
tunica vaginalis loops, having their convexities downwards.
This muscle draws the testicle upwards, an action very dif-
ferent from the corrugation of the scrotum.

  The Vas Deferens, or the proper excretory  duct of the
testicle, is a white tube of about  a line and a half in diame-
ter, and has a cartilaginous feel.   Its parietes are thick, as
its cavity will not receive a body larger than a bristle, with-
out being put upon the  stretch.   It traverses a long space,
and in doing so, first passes at the back of the chord  from
its commencement, to the internal abdominal ring; having
reached  the latter, it then abandons  the spermatic artery
and vein, and dipping  into the pelvis, by the side of the

      * Eat/?fev, a sheath.          \ See Abdominal Muscles. 
THE TESTICLES.                  93
bladder, goes between the lower fundus of the latter and the
ureter.  It then converges towards its fellow, along the un-
der extremity  of the bladder, at  the  inner margin of the
vesicula seminalis, of the same side, and finally terminates
in the urethra  near the  neck of the bladder.   About two
and a half inches from its termination it enlarges and be-
comes somewhat tortuous.
   This duct consists of two coats, the external one is  hard,
compact, and occasionally fibres are seen in it, but its struc-
ture is not very evident, and is peculiar.  The internal is a
mucous membrane.
   For the description of the remaining portions of the chord,
see Spermatic  Artery,  Vein, Lymphatics, and Plexus of
Nerves.

   The Testicles undergo a remarkable change in their posi-
tion, from the earliest development of their rudiments  to the
perfect foetal  state.  They are not formed in the  scrotum,
but in the abdomen just below the kidneys; from which po-
sition they are gradually transferred.   About the middle of
the third month of gestation they are two  lines long, and
placed behind the peritoneum, to which they loosely adhere.
The vas deferens then, instead of rising up on the side  of the
epididymis, goes straight down into the pelvis. At this peri-
od may be seen the  gubernaculum testis, discovered  by J.
Hunter,* which becomes more distinct in a few weeks after-
wards, and assumes a triangular appearance.  This guberna-
culum has the office of drawing  the testicle down into the
scrotum; its point commences in the upper part of the latter,
somewhat  below  the external abdominal ring;  it  passes
through the abdominal canal, ascends upon the iliacus  inter-
nus muscle, and is attached by its base to the inferior end
of the testicle.   In front of the  gubernaculum a process,
or small pouch of peritoneum, passes  through the  abdo-
minal canal to the  upper part of the scrotum.   By the con-
traction of the gubernaculum, the testicle is brought,  about
the seventh or eighth month, into the scrotum, by sliding
Med. Comment. Lond. 1777. 
94
ORGANS OF GENERATION.
✓
down behind the pouch.   The  lower end of the pouch at
which the testicle is finally arrested becomes the tunica va-
ginalis testis.
  As soon as the testicle has reached the scrotum, the neck
of the pouch has a tendency to close and to become oblitera-
ted, which is commonly accomplished at the period of birth;
yetitsometimes remains open for a longer time, and becomes
the occasion of congenital hernia.  Very generally, at birth,
the orifice of the pouch will receive the end of a probe to the
depth of a line or two;  but all below is perfectly closed, and
has its structure so condensed and altered that no one, from
a view of it alone, "would  suppose that the cavity of the tu-
nica vaginalis had ever communicated with that of  the pe-
ritoneum, t


     SECT. IV.--OF THE MUSCLES AND FASCLK OF THE
                       PERINEUM.

                    Perineal Fascia.

  The Perineal Fascia is placed  just beneath the skin of the
perineum, and covers the muscles,  It occupies nearly all
the space, between the anus and  the  posterior margin of the
scrotum, and between the rami of the pubes and the ischium
on each side; it is very firmly  fixed to these bones, and is
gradually blended with the cellular substance of the poste-
rior part of the scrotum.  This  fascia is rather thin, but, in
case of a rupture of the posterior part of the urethra, prevents
the urine from showing itself in the perineum, and drives
it into the cellular structure of the scrotum.  In abscesses of
the perineum, it also  prevents  the fluctuation from being
very evident.

  f The explanations and anatomy of this process have been treated at large
in the following works:
  Girardi, Tabul. II. adj. Septemd. Tab. Santorini.
  Hunter, Observations on certain parts of the Animal OZconomy.  W. Hun-
ter, Med. Commentaries.
  Edwardi Sandifort, Opusc. Anat.
  Wrisberg Comment. Medici Fhysiolog. &c. 
MUSCLES AND FASCIA OP THE PERINEUM.       95
             The Musculus Erector Penis,

  Is so  situated as  to  cover the whole of the crus of the
penis which is not  in contact with the bony margin of the
pelvis.   It arises, therefore, tendinous and fleshy, from the
anterior part of the tuber  ischii; its fleshy fibres adhere to
the internal and external margins of the rami of the pubes
and  ischium, and proceed  upwards; just  before the union
of the crura of the penis,  they end in a flat tendon which
is lost on the side of the elastic membrane of  the penis.*
  Its use is not well understood.


           The Musculus Accelerator Urinas,

  Lies on  the bulb and back part of the corpus spongiosum
urethrae; it is a thin muscle consisting of oblique fibres.
  It arises by a pointed  production from the side of the
body of the penis; its origin is continued obliquely across
the  inferior surface of the crus penis,  where the latter
begins to form the body of the penis.   It arises also for an
inch from  the inner side of the ramus of the pubes, between
the  crus penis and the triangular ligament of the urethra.
The muscles of the opposite sides are inserted into one ano-
ther by a white  line,  which marks the middle of the bulb
of  the  urethra; and by a point, into the anterior extremity
of the sphincter ani, where they are joined by the transversi
perinei.
   In order to see the  origin of these muscles  very distinct-
ly, separate  them  from each other in the middle line, and
dissect them from the corpus spongiosum.  Cut transversely
through the corpus spongiosum about  three  inches before
the  triangular ligament, and dissect it clearly from the cor-
pus cavernosum, turning it downwards so that it may hang
by the membranous part  of the urethra.   By putting the
two acceleratores on the stretch, it will  be seen that, besides
the origins mentioned, they arise also from each other by a

  * The late Dr. Lawrence informed me that he had frequently found mus-
cular fibres between the bone and the crus penis. 
96
ORGANS OF GENERATION.
tendinous membrane that is interposed between the corpus
spongiosum and cavernosum; so that they literally surround
the bulb of the urethra, constituting a complete sphincter
muscle for it.  This account of the accelerator urinae is pe-
culiar  to  myself.   I have  adopted it from the  strong ana-
logy between it and the sphincter vaginae.
   These two muscles  are  considered by M. Chaussier as
forming but  one; in that case  its origin will be reversed,
and commence in the middle line of the perineum instead
of terminating there.   As  this  muscle and the erector pe-
nis touch by their contiguous faces, it is difficult to get into
the membranous  part of the urethra in  lithotomy without
cutting through the muscular fibres of one  or the other.
   It propels the urine  and  semen forward.


          The Musculus Transversus Perinei,
   As its  name implies, passes directly across the perineum;
it arises from the inner side of the ischium, just at the ori-
gin of the erector penis, and is inserted where the sphincter
ani and acceleratores join.
   I have observed that when the lower part of the accelera-
tores was extended  much below their usual line,  and strong-
ly developed, that  the transversus was  very irregular  in
its origin and course; consisting frequently of a few fibres
which did not  deserve the  name of a distinct muscle, and
lying almost unappropriated in the adipose matter of the
part.
  Occasionally a fasciculus  of muscular fibres exists, called,
by Albinus, Transversus Perinei Alter, which arises in front
of the former muscle, and is inserted into the perineal junc-
tion just behind it.
  The use of these muscles seems to be to contribute to fix
the bulb of the urethra.

             The Musculus Sphincter Ani,

  Consists in a plane of fibres which surrounds  the anus in
order to  keep it closed.   It has two fixed points, the last 
        MUSCLES AND FASC12E OP THE PERINEUM.       97

bone of the os coccygis behind, and the perineal union of
the other muscles in front; its lateral diameter occupies about
one-half of the space between the tuberosities of the ischia,
and it is in the middle of this space.
  Besides closing the orifice of the rectum it will draw the
bulb of the urethra backwards, or the point of the os coc-
cygis forwards.

                The Musculus Coccygeus,

  Belongs to the interior of the pelvis.   It arises  by a
small, tendinous, and fleshy beginning, from the  spine of
the ischium, and, lying on the anterior face of the anterior
sacro sciatic ligament, it is inserted into the side of the last
bone of the sacrum and of all those of the os coccygis.
   It draws the os coccygis forwards.
   A large quantity of adipose and cellular matter exists on
the side of the rectum, between it and the parietes of the
pelvis, concealing the perineal surface of  the levatores  ani
muscles.

               The Musculus Levator Ani,

   Arises fleshy from the  back of the pubes near its sym-
physis, and from near the superior margin of the foramen
thyroideum above  the obturator internus muscle.  It also
arises from the aponeurosis pelvica, where this membrane is
extended as a thickened semilunar chord  from the superior
margin of the thyroid foramen towards the spinous process
of the os ischium.   This second part of  the origin of  the
levator ani is defectively described in most books on ana-
tomy.  It is then seen to cross obliquely, as far as the spine
of (lie ischium, that portion of the obturator internus which
arises from the plane of the ischium.
   From this extensive origin the fibres converge and descend
backwards, and have three distinct places of insertion;  the
posterior fibres  are  inserted  into  the two last bones of the
os coccygis; the middle, and by far the greater number,  are
inserted into the semi-circumference of the rectum between
   Vol. II.—13 
98
ORGANS OF GENERATION.
its longitudinal fibres and the circular fibres of the sphincter
ani; and finally,  the  most  anterior fibres pass obliquely
downwards and backwards on the side of the vesical end of
the membranous part of the urethra, and on the side of the
prostate gland, and are inserted  into the common place of
junction of the perineal muscles.

      The Triangular Ligament of the Urethra,

   Is a membrane which fills up the space below the sym-
physis of the pubes, and answers as a septum between the
perineum and the pelvis; when closely examined, it is seen
to connect itself to the internal edges of the rami of the pubes
and ischia on the inner posterior sides of the crura penis as
far down as the beginning of the latter.   At its lower edge
its ligamentous character is not so well defined.   On its an-
terior surface is the bulb of the urethra, and just at the ex-
tremity of the latter, enclosed by the ligament and adhering
to it, are Couper's Glands.  A perforation exists in it, through
which passes the membranous part of the urethra.   This
opening is not very apparent, in consequence of its edges
being continued a little distance on the canal, but by detach-
ing them the whole becomes well defined.
   The relative situation of the bulb and of the membranous
part of the urethra  is such, that the former goes towards the
anus, while the latter passes upwards towards the neck of
the  bladder, they consequently form a considerable  angle
with each other.   The membranous part of the  urethra is
much the deepest, the recollection of which is all important
in lithotomy, as it teaches us to avoid the  one, and  to  cut
into the  other.   It may also be observed,  that the  hole in
the  triangular ligament is  an  inch below the symphysis
pubis.
   By removing the upper corner of the triangular ligament,
 we are made acquainted with another just behind it, which
 is totally distinct.   This ligament is half an inch broad, is
 thick and strong, particularly at its lower edge, and is very
 firmly  attached laterally to each pubes, just below the sym- 
PELVIC FASCIA.
99
 physis.  Mr. Colles calls it pubic ligament, with great pro-
 priety; I would suggest as somewhat more expressive, the
 term Inter-Pubic ligament, as it serves to distinguish it from
 another called  pubic, which is above  the pubes,  and  de-
 scribed in  the account of the recti abdominis muscles.  The
 breadth of this  having been stated at half an inch, it is ob-
 vious that  the hole in the triangular ligament, is half an inch
 below its lower edge.


                    Pelvic Fascia.

   The Pelvic Fascia  (Aponeurosis Pelvica) connects  the
 bladder to  the sides of the pelvis. *(This fascia descends from
 the ilio-pectineal  line to  about midway in the depth of the
 pelvis; here  it is reflected from the surface of the  muscles
 (the Levatores Ani) and applies itself to the prostate gland
 and bladder  on  the body of which it is ultimately lost.   At
 the angle  of its  reflection,  this  fascia appears particularly
 strong and white,  but  becomes more weak and thin as it
 lines  the muscles  and covers the  bladder.  In tracing this
 membrane if will be seen that from the pubes just below the
 symphysis, a pointed production of it constituting its anterior
 margin is fixed  into the  side of the neck of the bladder.
 This  pointed production on each side is called by most ana-
 tomists the anterior Ligaments of the  bladder.  Between
 them, just  beneath the symphysis of the pubes, a pouch laro-e
 enough to  receive the end of the  finger,  is formed by  the
 union of the  fasciae of the two sides; this pouch  connects
 the middle anterior part of the neck of the bladder to  the
 lower margin of the symphysis pubis.'**
  This fascia adheres closely to the periosteum of the pubes
 between the  upper margin of the thyroid foramen  and the
 crista of the  pubes; about the middle third of the linea  in-
nominata it is obviously a continuous membrane with the iliac
fascia  which covers the iliacus internus muscles;  but behind
 this,  again, it arises from the remaining third of the linea
 innominata.

                 * Colles' S'irgical Anatomy, 
100
ORGANS OF GENERATION.
  The portion of this fascia which Mr. Colles speaks of as
particularly strong and white, forms a bow, the concavity
of which looks upwards, one end of the bow being fastened
to the pubes above the foramen thyroideum, and the other
end to the ischium above its  spine.  The perineal surface
of this bow is an important  point of the origin of the le-
vator ani.   Above the bow this  fascia is very thin,  for
the fibres  of the  obturator internus  can be readily seen
through it.
  At the bow the fascia divides into two laminae, one pur-
suing its course to the bladder and rectum; the other covers
 the lower  part of the obturator internus muscle, and there-
by  constitutes the obturator  fascia.  The levator ani is  in-
terposed between the two laminae.  The aponeurosis pelvi-
ca also forms a bow or semilunar edge in front of the sacral
nerves.
                   CHAPTER  II.

   OF THE ORGANS OF GENERATION IN THE FEMALE.

  The Copulative Organs in the female are, the Vulva and
the Vagina; the Generative are the Uterus and the Ovaria.


               SECT. I.--OF THE VULVA.

  The term Vulva is applied  to the most superficial of  the
copulative organs, and consists in the  Mons Veneris,  the
Labia Externa, the Labia Interna, the Clitoris, the Vesti-
bulum, the Orificium Urethrae, the Fourchette, and the Fos-
sa Navicularis.

   The Mons Veneris is  the  protuberance on the fore part
of the pubes.   Its size varies considerably according to the 
THE VULVA.
101
state of obesity of the subject,  in  consequence of its being
formed by a deposite of fat between the skin and the bone;
in corpulent women it is very large and prominent, where-
as in such as are much emaciated it simply describes the
outline of the bones.  The skin there  is abundantly fur-
nished with sebaceous glands seated in the cellular  texture
beneath it, and about the size and shape of mfllet seed.   At
the age of puberty a growth of hair  takes  place upon it,
which is not so long as the correspondent growth upon men,
and is not so much disposed to spread itself over the lower
part of the abdomen,  as  life  advances.  In women who
have abused coition these  hairs become much curled.

   The Labia Externa are a  continuation of the mons vene-
ris downwards in  the form of an oblong eminence on either
side.   Their elevation is  produced in the same way by a
deposite of  fat  beneath  the  skin.   They are somewhat
broader  and more prominent above  than below.  On the
side which is next to the thigh the integument is common
skin, sparingly covered with  hair; but on the other face it
is a mucous membrane, being a continuation of  that of the
vagina.  The skin here, as well as at the commencement of
every mucous membrane, is insensibly changed into  the
latter.   They have many sebaceous glands externally,  and
mucous glands internally, upon them.
   Much  cellular  membrane,  like that  of  the scrotum, is
found in their interior structure, whereby they  enjoy great
extensibility in  order  to  favour the dilatation of the parts
in parturition. The rima which exists between them is the
Fissura Vulvae of authors, and is about  twice the length of
the  orifice of the vagina: this arrangement  of it gives in-
creased facility to the expulsion of the foetus.

   The Fourchette or Frenulum Vulvae, is situated at the
posterior commissure  of the  labia externa, and is a thin,
narrow transverse duplicature of skin, which, owing to its
weakness, is most frequently ruptured at the  first act of
parturition, and then disappears. 
102
ORGANS OF GENERATION.
   The Clitoris bears,  in some respects, a resemblance to
 the penis of the male, but is by no means so large.   It is
 situated immediately below the symphysis pubis, and con-
 sists in a cylindrical body of three or four lines in diameter,
 with two crura.  The body is an inch long; the crura are
 likewise of the same length, and  arising from the internal
 face of the corresponding crus of the pubes, unite beneath
 the symphysis so as to  form the body.  The body is not
 straight, but has the anterior half bent downwards and for-
 wards.  The exterior  covering, or capsule of the clitoris,
 in its texture, resembles  the elastic ligamentous membrane
 of the corpus cavernosum penis; and is moreover,  filled
 within by a similar cavernous or cellular structure, which is
 divided into two  equal parts by a septum pectiniforme, and
 is susceptible of distention during sexual excitement.   The
 clitoris is supplied also with  blood vessels  and nerves like
 the penis, and is held up to the  under part of the symphy-
 sis pubis by a suspensory ligament.
  The anterior extremity of the  body of the  clitoris is
 found in  the rima vulvae,  about an inch below the upper
 commissure  of the  labia externa.   It  projects somewhat,
 and bears a general resemblance in shape with the end of
 the penis, whence its  name of glans clitoridis; but it has
 not the same organization,  excepting the delicacy, the ex-
 treme sensibility, and the vascularity of the skin which co-
 vers it.  The clitoris has no corpus spongiosum, neither is
 it concerned, like the  penis,  in conveying the urine from
 the bladder.   Its glans is  covered by a doubling of  skin
called the prepuce, and is likewise  furnished with the glan-
 dulae Tysoni, from which is  discharged  a smegma, or se-
baceous fluid as in the male. The prepuce does not furnish
a regular well defined fraenum.
  The Erector Clitoridis  muscle corresponds with the erec-
tor penis.   It arises from the ascending ramus of the ischi-
um, and, covering the inferior  face of the crus clitoridis,
runs as far forwards as the commencement of the body.

  The Labia  Interna are two duplicatures of thp mucous 
THE VULVA.
103
membrane of the vulva, which pass down, one on each side,
from the clitoris.  The prepuce of the latter terminates, on
either side, in the labia,  while  the latter are continued up-
wards,  by a  narrow  process, to the under  surface of the
glans clitoris.   They arise, all along their base, from the
internal sides of the  labia externa,  or  majora; and being,
wider in the middle than elsewhere, they terminate insen-
sibly about half way  down the orifice of the vagina.  Be-
tween the laminae of  each  one  is placed a vascular cellular
substance, susceptible of distention  and of partial erection
during  sexual excitement.   In  young subjects their vascu-
larity communicates  a vermilion tinge, which is  lost and
becomes brownish in the progress of life.  As they are ef-
faced during parturition, their chief use seems to be a pro-
vision for the great distention of the vulva, which then oc-
curs.
   The  labia interna are about half an inch broad in the na-
tural state, and  do not project obviously beyond  the labia
externa, except in cases of extreme emaciation, where the
prominence of the latter has been destroyed by a removal
of its fat.  They are, however, very subject, as the indivi-
dual becomes old, to a pointed elongation, increasing their
breadth to an inch,  or  an inch  and a half; and to become
thickened and indurated.   A tribe of Hottentots,  the Bos-
chismans, living near the Cape of Good Hope,  are uniform-
ly subject to this  enlargement; which,  for a long time was
represented,  by travellers,  as an organ  superadded to what
is common in the human species.

   The  Vestibulum is a depression of twelve or fifteen lines
long, between the labia interna; it is bounded above by the
clitoris  and below by the orifice of the vagina.   It  is abun-
dantly furnished with mucous lacunae.

   The Urethra of the female has its external orifice (Ori-
ficium  Urethrae) in the  inferior part of the  vestibulum
about one inch below the glans clitoridis, and  is generally
marked by a slight rising, which is  easily distinguished by 
104
ORGANS OF GENERATION.
the sensation of touch alone; its margin is often bounded by
a little caruncle on each side.   The urethra itself is an inch
long, larger and much more dilatable than that of the male;
its course is obliquely downwards  and forwards from the
neck of the bladder; passing under the symphysis of the
pubes, and being slightly curved  from that cause.  It con-
sists of two membranes, a lining and an external one.  The
lining  membrane is a continuation  of that of the bladder;
it is  thrown into  several longitudinal folds, and has many
mucous follicles  in  it.   The  external coat of  the  urethra
consists of condensed laminated cellular membrane, forming
a cylindrical body of half an inch  in its transverse diameter,
and which has given the idea of the existence of  a prostate
gland in the female.  The lower and lateral surfaces of this
cylinder are in contact with the vagina, forming a protube-
rance  into its  cavity; and the upper surface  is firmly con-
nected to the triangular ligament  of the pubes.

  The Fossa Navicularis is that portion of the rima vulvae
which is below the vestibulum, and anterior to the orifice
of the vagina.


               SECT. II.--OF THE VAGINA.

   The Vagina is  a thin  membranous canal which leads from
the vulva to the uterus.  It is from four to six inches in
length, differing according to age and pregnancy, and  bein«-
much  shorter in  women who  have  borne children than in
virgins.   It is placed between the bladder in front and  the
rectum behind, being flattened by  them so  as to bring its
anterior and posterior surfaces into contact.    Its anterior
extremity is the smallest of the two, and presents its great-
est diameter vertically,  while that of the posterior is  trans-
verse.   As it follows accurately  the central line of the pel-
vis,  it is consequently curved with  its concavity forwards.
Its anterior parietes are shorter than  the posterior,  both from
the smaller depth of the pelvis in this direction,  and from
their mode  of connexion with the uterus. 
THE VAGINA.
105
   The vagina is formed by two tunics;  a fibrous and a mu-
cous one. The  first is external, of a light red colour, highly
clastic, and seems to consist of condensed cellular membrane,
the fibres of which are much intermixed, and pass in every
direction.  It is vascular, and  immediately adjacent to the
large venous  sinuses of the pelvis.   The mucous membrane
being a continuation of that of the vulva, is at and near its
anterior orifice of a vermilion tinge; while  posteriorly it
is grayish and frequently spotted, so as to give it a marbled
appearance;  its thickness diminishes as it recedes from the
external orifice; and upon being floated in water many mu-
cous lacunae are observable upon it.
   The  internal surface of the vagina is commonly covered
with the mucus which comes from  its lacunae.  On the an-
terior or pubic  portion it is divided  longitudinally by a mid-
dle ridge, which commences by a sort of tubercle just below
the orifice of the urethra, and proceeds backwards, becoming
indistinct as it approaches the uterus.   Transverse ridges
formed in the same way by folds of the mucous membrane,
arise from the sides of the last at  its anterior portion, and
give a roughness to that part of the vagina.  The inferior
side, or that  next to the rectum, has the same kind of ar-
rangement of the mucous membrane, but not so distinct.  In
a majority of subjects the uterine half of the vagina is per-
fectly smooth,  but the rule does not always hold.

   The Corpus Spongiosum Vaginae is an erectile tissue like
that of the penis, and closely resembles in structure the cor-
pus spongiosum urethrae.  It is placed at the anterior end
of the vagina,  on its outer circumference, just below the
clitoris, and at  the base of the labia minora or interna.   It
is  an inch broad, and a line or two  thick,  adheres closely
to the fibrous coat of the  vagina, and extends around the su-
perior semi-circumference of the orifice, but not around the
inferior.  It  is  frequently called Plexus Retiformis.

   The Sphincter Vaginae Muscle surrounds the anterior ori-
     Vol. II.—14 
108
ORGANS OF GENERATION.
fice of the vagina, and covers the  plexus retiformis.  It is
about an inch and a quarter wide, and arising from the body
of the clitoris passes backwards and downwards to be in-
serted into the dense, white substance, in the centre of the
perineum, common to these muscles, the transversi perinei
and the anterior point of the sphincter ani.

  The Transversus Perinei of the  female, has the same cir-
cumstances of origin and insertion as in the male, but is not
quite so strong.

  On each side of the orifice of the vagina,  near its middle,
is frequently found  a mucous gland the size of a garden pea:
it corresponds with Couper's gland of the male subject.

  The Hymen,* one of the attributes of the virgin state, is
placed at the anterior orifice of the vagina for the purpose
of closing it, and commonly remains until it is ruptured by
violence.  In all cases, except where there is an unnatural
adhesion, it leaves  a small orifice for the passage  of mucus
and of menstrual blood.   In my own observations, I have
found it  most frequently crescentic, the  convexity of the
crescent presenting downwards, and the horns upwards, but
in some cases it is to one  side.  Next in frequency to the
lunated is the circular shape, where it surrounds complete-
ly the orifice and leaves a hole in  its own centre.   There
are some other varieties, such as  its being fleshy, fasci-
culated,  unequally divided into two portions, and so  on,
which are narrated by  different writers.   Being simply a
duplicature of the mucous membrane, it is generally so weak
as to be ruptured at the first act of copulation, or even from
slighter causes durjcg infancy;  but occasionally it becomes
thickened and so strong as to require division with the knife.
After the rupture of the hymen its place is indicated in sub-
sequent life by, from two to six small tubercles, called Ca-
runculae Myrtiformes, which are its remains.

  * J. G. Tolber. Diss, de Variet Hymen.  Haller, Icon. Anat. Fasc. i,
Albin. Acad* Annot. Lib.iv.  Santorini, Septemd. 1'ab. 
UTERUS AND ITS APPENDAGES.
107
  The peritoneum, in descending from the uterus anteriorly,
touches the top of the vagina for  a little distance,  and is
then reflected to the bladder, but posteriorly, almost- the
upper half of the vagina has  a peritoneal  coat before this
membrane is  reflected to the  rectum.   The attachment of
the vagina to the bladder is strong and close just about the
urethra,  but  its connexion with  the rectum is  by rather
loose cellular substance.
     SECT. III.—OF THE UTERUS AND ITS APPENDAGES.

   The Uterus, or womb, is a compressed pyriform body,
 the larger end of which stands upwards, while the lower is
 directed downwards and is attached to the vagina.  Unim-
 pregnated, it is two and  a half inches long, and  one and a
 half in diameter at  its widest  part.  The posterior face is
 Very convex, while the anterior is almost flat or very slight-
 ly convex. It is about one inch in thickness.  It is divided
 by anatomists into fundus, body, and neck.   The fundus is
 formed by its superior extremity, and comprises the space
 between the orifices of the fallopian tubes; the neck is the
 lower cylindrical portion, of about an inch in length; and
 the body is the part intermediate to the two.   On the ex-
 terior circumference of the uterus there are  no  marks or
 lines distinguishing  these several portions from each other.
   The uterus, being destined  to  lodge the foetus, from a
 short period after conception to the moment of birth,  has a
 cavity ready for its reception.   The shape of this cavity
 bears some general but  not a rigid resemblance  to that of
 the organ itself, and is so much flattened as to have its an-
 terior and  posterior parietes in contact or nearly  so.  The
 cavity of the body is an equilateral triangle of eight or ten
lines in diameter; the sides of the triangle are bent inwards
in parabolic curves, in such a way as to present their con-
vexities to the cavity of the uterus: this of course  occasions
 an apparent elongation of the angles   The inferior angle 
108
ORGANS OF GENERATION.
is continued into the cavity of the neck, while  the two su-
perior run into their respective fallopian tubes.   From this
arrangement it happens that the parietes of the uterus are
only two or three lines thick on the angles of the triangu-
far cavity, while  at  the middle they are from  four to six
lines.  The cavity of the neck has not its anterior and pos-
terior sides so near together as that of the body, and  is ra-
ther cylindrical,  being smaller however at the upper and
lower ends than in the middle.  This  arrangement  gives
to its sides a  paraboloid curvature which presents its con-
vexity outwards,  differing in that respect from the corres-
ponding curvature in the cavity of the body.
  The cavity of  the neck terminates in the vagina by an
orifice about the size of a small writing quill, but ovoidal,
and presenting its long diameter transversely.   This orifice
is the Os Tincae, or Orificium Externum Uteri;  frequently
without apparent disease I  have seen it conoidal, with its
base, half an inch in diameter, presenting downwards. The
upper orifice, whereby the cavity of the  neck communicates
with that of the body, is not subject to such fluctuations in
size;  it is occasionally called orificium internum uteri, and
is generally somewhat larger than a small writing quill.
The os tincae  is bounded  before and behind by the lips of
the uterus, formed by the projection of the neck into the
vagina.   For  the most part the anterior side of the vagina
is directly continuous with the  anterior lip, so that its pro-
jection is very inconsiderable, and  indeed not appreciable
to the finger; at the same time, this lip  is rather thicker
than the posterior. The projection of the latter, on the con-
trary, is always well marked, because the vagina instead of
being inserted into its ridge is joined to the posterior sur-
face of its base.
  The cavity  of the uterus is lined by a very thin mucous
membrane, a continuation of that of the vagina. This mem-
brane is of a light pink colour, which changes to a vermilion
during the period of menstruation; it is furnished with vil-
losities, which, though seen with difficulty in the usual way,
may be rendered apparent, by floating the  uterus in water; 
              UTERUS AND ITS APPENDAGES.          109

and it adheres so closely to the substance of the uterus, that
it seems to form an inseparable  portion of it, which can
neither be dissected or macerated off entirely, as in the case
of other mucous membranes.
  This membrane is  smoothly laid upon the cavity of the
body,  and  gives  it a polished  shining surface.  On the ca-
vity of the neck, it is wrinkled along the anterior and the
posterior parietes; there being a longitudinal line running
along the centre, and on each side of this line transverse or
oblique elevations  or duplicatures; the whole presents an
arborescent appearance, technically called the arbor vitae.
In the interstices of these duplicatures there are some small
mucous glands or lacunae, which as their orifices are exposed
to obliteration from  inflammation or some other irritation,
they become distended into small spherical sacs by the ac-
cumulation of their habitual secretion.  Naboth, from  seeing
them in this state, mistook them for eggs, or the rudiments
of the foetus, and the error has been commemorated by their
being called Ovula Nabothi.

  The uterus  is covered completely by the peritoneum; in
the reflection of the latter  from the rectum to the bladder,
it adheres to the uterus by a  subjacent cellular substance,
which allows it to be dissected off without difficulty.  The
same duplicature of peritoneum which encloses the uterus,
is also reflected from each of its lateral margins, by their
whole length, to the corresponding side of the lesser pelvis,
and forms the Lateral or the Broad Ligaments, (Ligamenta
Lateralia, Lata.)  The peritoneum, in passing from the ute-
rus forwards to the bladder, forms, on each side, a duplica-
ture not very distinct, and depending in a measure, upon
the state of the bladder; this constitutes the Anterior Liga-
ments.  The same  membrane, in passing from the back of
the uterus to the  rectum, and in covering the posterior su-
perior  end of the vagina, also forms, on each side, a dupli-
cature  denominated  the Posterior  Ligaments;  they are
always better seen than the anterior.  Muscular fibres are
said to be found occasionally between the laminae of these 
110
ORGANS OF GENERATION.
 several duplicatures, running in the direction of the latter;*
 they have not been presented to me in such a way as to ar-
 rest my attention.
   The broad ligaments, along with the uterus, form a trans-
 verse septum, passing from  one side  of the pelvis to the
 other,  and contain, between  their laminae, the arteries and
 the veins  which belong to the uterus and ovaries.
   Besides the duplicatures of peritoneum, the uterus is re-
 tained in  its position by the Ligamenta Rotunda, one on
 each side. These round ligaments arise from the sides of the
 uterus, a little below the insertion of the Fallopian tubes,
 and  going between the laminae of the broad ligament, reach
 finally the internal abdominal ring;  they then traverse the
 abdominal canal and the external ring after the manner pre-
 cisely  of  the spermatic chord, and terminate by several
 fasciculi in  the  fatty cellular matter of the mons veneris
 and  of the labia  majora.  The round  ligaments are rather
 smaller in the middle than at either extremity; 4:hey consist
 of a  condensed cellular or fibrous structure, and have many
 blood vessels in  them.  It has been assertedt that they  con-
 tain  strongly marked muscular  fibres, some of which come
 from the uterus, and others from the broad muscles of the
 abdomen.   No evidence of this fact has  as yet been  pre-
 sented to me,  though I do not deny it; and, indeed, think
 it probable, that such fibres may be developed there during
 gestation.

  The texture of the uterus is very compact, and of a carti-
 laginous feel; it  is  composed of fibrous matter intermixed
 with a great many blood vessels.  In  regard to its fibrous
structure,  there is no subject in anatomy on which opinions
are more divided; or more authoritative, and numerous on
both sides of the question.  Some deny its existence  at  any
period, while others admit it as a constant condition; others,
again, limit  its duration only to  the period of pregnancy.

                * J. F. Meckel, vol. ii. p. 605.
                f J. F. Meckel, loc. cit. 
UTERUS AND ITS APPENDAGES.          111.
Without dwelling on the value of the several doctrines, and
the means and observations tending to support them; it may
be sufficient here to mention that the structure of the uterus
takes on very important and  strongly marked changes, in
passing from the unimpregnated state, to that of advanced
gestation.  In the first the fibres look ligamentous and pass
in every direction, but so as to permit the uterus to be lace-
rated more readily from the circumference to the centre than
in any other course; it, indeed, manifests an indisposition
to be torn in a laminated manner.  The fibres, moreover,
break off short, are separated by the blood vessels, and seem
to contain, in their interstices, something like fibrine.
   In the impregnated state, on the  contrary, the vessels
become immensely increased in size, the laminated struc-
ture becomes very  evident, and submits readily to the tear-
ing  of one layer from the other; these laminae consist of
fibres, which are principally parallel with each other.   The
muscular nature of these fibres  seems  to be sufficiently
proved, by their powerful  contraction in the  expulsion of
the foetus, and on being irritated by the introduction of the
hand.  They are, however, not red like other muscles, but
of a very light colour, as those of the bladder and intestines;
and are collected into fasciculi of peculiar flatness and loose-
ness.   The development of this  muscular structure is not,
however, limited to  the pregnant state, but is disposed to
manifest itself on all occasions which produce an increased
size in the uterus.  This fact was first exemplified to me in
a small scirrhus of a virgin uterus, presented by Dr. Hugh
L. Hodge, and has been still further confirmed in a case,
where the scirrhus was five or six inches in diameter;  also,
in a virgin uterus,  very much enlarged from scirrhus, pre-
 sented by Dr. Charles D. Meigs.  A similar fact has  been
noticed by Lobstein, of Strasbourg, where the tumour was
also steatomatous.
   The fibres of the uterus, examined  near the term of preg-
 nancy, consists in two planes separated by the large blood
 vessels, one within and the  other without.  These layers
 are readily divisible into  subordinate lamina?,  intermixed 
112             ORGANS OF GENERATION.
with one another, but yet to a considerable extent sepa-
rable.  The external layer is thicker than the internal, and
both have an increased thickness at the fundus, while they
are much diminished, and indeed indistinct, at the cervix.
  The fibres generally are either circular or longitudinal,
but many of them are oblique.  The exterior surface  of the
external plane, is composed principally of longitudinal fibres,
within which are the circular. The inner plane, on the con-
trary, has the circular fibres external, and the longitudinal
internal.   In both planes the circular fibres are  more abun-
dant at the fundus,  and the longitudinal upon the body of
the uterus;  but, generally speaking, there are collectively
more longitudinal than circular fibres.


               Of the Fallopian  Tubes.

  The Fallopian Tubes (Tubas Fallopianas) are two  mem-
branous canals, one  on  either side, fixed in the superior
margin of the broad ligaments of the uterus.   They serve
to conduct the rudiments of the embryo, from  the ova-
rium into the uterus.  They are about four inches long,
and extend  from the upper angle of the uterine  cavity to
the side of the pelvis; their outer extremity is loose, and
hangs upon the posterior face of the broad ligament over the
ovarium, consequently inclines downwards, thereby form-
ing an  angle with the other portion.
  At their uterine extremities the fallopian tubes are about
the size  of  the vas deferens, resemble  it strongly, and
scarcely admit a hog's bristle; but  having proceeded about
one half of  their length, they begin  to enlarge, and con-
tinue to  do so rapidly for an inch,  until  they reach  the
size of a writing quill; they then contract again somewhat,
and immediately afterwards expand  into a broad trumpet-
shaped mouth.   The latter has an oblique orifice, the edge
of which  is extremely irregular, by being resolved  into a
number of ragged fringe-like processes, of unequal size and
length: and which,  as a whole, are  called Corpus  Fimbria- 
UTERUS AND ITS APPENDAGES.
113
 turn or Morsus Diaboli.   One of the longest of these pro-
 cesses adheres to the external end of the ovarium.
    The fallopian tube is covered  by the peritoneum, and
 consists of two coats: the external is fibrous, and bears suf-
 ficient resemblance to the structure of the uterus to be con-
 sidered a continuation of it;  the internal is mucous, and is
 likewise a continuation of the corresponding one of the ute-
 rus.   The external end of the tube, which is called  Pavil-
 ion by the French anatomists, is flaccid, thin, and generally
 in a collapsed state, as  it is  formed solely by the mucous
 membrane, assisted by the peritoneum, neither of which fur-
 nishes resistance sufficient to keep it expanded; but, as many
 blood vessels enter into its composition, their turgescence,
 in sexual excitement, probably communicates a certain de-
 gree of erection.


                     Of the  Ovaries.

   The Ovaries, (Ovaria,  Testes Muliebres,) two in num-
 ber, one on either side, are situated on the posterior face of
 the broad ligaments, by a duplicature of which they are sur-
 rounded, and are twelve or fifteen lines  below the fallopian
 tubes.  Their shape is that  of a compressed ovoid, about
 half the size of the male testicle; their long diameter is ho-
 rizontal; they are suspended from the broad ligament rather
 by the edge than by the flat surface, so that they project,
 and are to a considerable degree pendulous.  Their distance
 from the uterus varies from an inch to  an inch and a half,
 and from  the internal  end of each one, there proceeds a
 small vascular fibrous chord, the Ligament of the Ovarium,
 which is inserted into the uterus, somewhat below the ori-
 gin of the fallopian tube.
  From their being the seat  of conception, they  have, in
the youthful and healthy female, a pliancy and succulency,
indicative of their state of preparation for the act; but in
advanced life they diminish much  in volume and  become
hard and dry.  Their surface, originally smooth or  slightly
  Vol. II.—15 
114
ORGANS OF GENERATION.
embossed;  is subsequently rendered uneven,  by repeated
acts of conception leaving on it, a number of  cicatrices or
small stellated fissures.   They are of a light pink colour.
Within the peritoneal coat is another, the Tunica Albugi-
nea, of a strong,  compact, fibrous texture, like the same
coat of the testicle, and sending inwards many processes.

  The  structure  of the ovarium  is not ascertained  with
entire satisfaction, though the grosser arrangement of it is
known.  But few females, of such as are presented in our
dissecting rooms, have these parts in a state fit for study,
owing to age, disease,  or intemperate  sexual indulgence;
my best opportunities have been derived from  post mortem
examinations in private, of individuals of from fourteen to
twenty, where the virgin state had been preserved. When
an ovarium of the latter  kind  can be got, by cutting through
the tunica  albuginea simply, and then tearing open the
organ, it will be  found  to consist in a spongy  tissue, abun-
dantly furnished with blood vessels from the spermatic ar-
tery and vein.  In this  spongy tissue are from fifteen to
twenty spherical  vesicles (Ovula  Graafana) varying in
size from half a line to three lines in diameter; the larger
ones are nearer the surface, and from having caused the ab-
sorption of the tunica albuginea,  may sometimes  be seen
through the peritoneal coat,  and  give to the surface of  the
ovarium its embossed condition.  The vesicles contain  a
transparent fluid  supposed to be,  or to have within it,  the
rudiments  of the embryo.   As  the vesicles  are  evolved
they advance from the centre to the  circumference.  Their
parietes are thin, transparent, and have creeping through
them minute arterial and venous ramifications.

   The organs of  generation in the female are supplied with
blood principally from the internal pudic and other branches
of the hypogastric artery; their veins run  into the hypo-
gastric.  Their nerves come from the sacral  and  from the
hypogastric plexus. 
THE LACTIFEROUS GLANDS.
115
  The  Bladder  and  the Rectum,  with  unimportant ex-
ceptions are the same in both sexes.  The Levator Ani, the
Coccygeus, and the Sphincter Ani,  are also similar.  The
pelvic aponeurosis in the female, besides  connecting the
bladder to the sides of the pelvis, is also attached to the an-
terior part of the vagina.   The  triangular ligament of the
urethra also exists, but under circumstances somewhat mo-
dified by the  close  connexion of the urethra with  the va-
gina.
                      CHAPTER III.

        OF THE LACTIFEROUS GLANDS OR BREASTS.

   The Breasts  (Mammae) of the female, are intended for
the secretion of milk, and thereby to maintain the connex-
ion between mother and infant, for some time after the ute-
rine life of the latter is passed.   All mammiferous animals
exercise this function; in  birds there is a sort of substitute
for it, in the changes which take place in the first stomach
or crop during incubation.  In the male subject there is also,
a  small glandular body on each side, which has the same or-
ganization as in  the female, but is in miniature, and always
remains in a  collapsed state, with  some rare  exceptions,
when it has been known  to expand in volume, and to fur-
nish a secretion, as in the female.*

  * In a male patient, now resident in the Philadelphia Alms House, the
phenomenon of a full evolution of the glandular structure in both breasts is
manifested.  The individual (James Mclntyre) is forty-five years of age,
the breasts are as large as  those of a nursing woman, but the nipples are
not proportionately evolved. Though his frame is robust, and well set, the
voice is feminine; his external organs of generation are about the size of
those of a boy of fourteen or fifteen.  Thinking that there might be an in-
ternal state approaching to hermaphrodism, he informed me, on inquiring,
that in earlier life he h;«d the usual inclinations for the female.  He also in- 
116
THE LACTIFEROUS GLANDS.
   The breasts are two in number, one on either side; they
 are  situated on  the  same level,  in  front of the pectoralis
 major muscle, and between the  arm pit and the sternum.
 They are hemispherical, and have their base united to the
 muscle by a thin lamina of loose, extensible,  cellular sub-
 stance, containing, even in corpulent women, but little fat.
 The skin which covers the front of this gland is very fine and
 thin, so that the blood which circulates in its veins may be
 readily seen.   Between the skin and the front surface of
 the  gland, there is a  considerable thickness of  cellular adi-
 pose matter, which,  from its superabundance in certain in-
 dividuals, gives to them an appearance of having the glands
 enormously enlarged.   There is, however, a great variety
 in the size of the glandular  structure itself; for in females
 who are  youthful  and giving  suck,  they are  much larger
 than in such as have passed the period.of child-bearing, and
 whose health  is impaired.  When all the fatty matter has
 been removed from a breast, and it  is permitted to repose
 upon a table, its hemispherical shape disappears, and it  then
 seems rather a flattened circular disk, of from  four to five
 inches in diameter.
  The mamma is of a very light  pink colour;  and though
 very flaccid and yielding on being handled, yet its texture
 is actually extremely tough, and is cut only by  much force.
 With the exception of bone, it dulls  the knife  sooner  than
 any other tissue of the body.  Its grosser arrangement con-
 sists in lobes of different sizes,  united in such a  way by cel-
 lular texture, that, though they  can be pulled somewhat
 apart,  they cannot be entirely separated without  injury.
 These lobes, when examined through the skin, give to the
 gland a knotted  feel, and  are  sometimes partially affected
 by inflammation, so as to become  still more distinct.   The
Lobes are composed of Lobuli, which are resolvable by ma-

 formed me that this unusual development took place seven or eight  years
 ago, owing to an excessive salivation; but as he has a reserve on the sub-
ject, this statement may probably be received with some qualifications. I
 have also seen a second case, in which the voice is weak and feminine, the
generative organs have not been examined. July, 1826. 
THE LACTIFEROUS GLANDS.            1)7
 ceration and particular modes of treatment, into small gra-
 niform masses  (acini) about  the size of millet  seed, and
 which contain the ultimate glandular arrangement.   The
 acini themselves  consist  of very  small  oblong  vesicles.
 united by cellular substance, and by the common blood ves-
 sels; and are  said to be very apparent by the aid of a mi-
 croscope in a lactescent gland.*
   The excretory ducts (Ductus Galactophori, Lactiferi)
 of this gland are numerous, t   They are of an arborescent
 shape, and begin  by very fine extremities or ramuscles in
 the acini; the ramuscles from several acini coalesce into a
 larger  branch; several branches  unite to  form one still
 larger, and so on successively until a lactiferous duct, con-
 stituting as it were the body of the tree,  is formed by this
 assemblage.   These  trunks vary considerably in size, ac-
 cording to  the number of tributary branches, and having
 got towards the  centre of the gland near the nipple, from
 two to four of them, according to  Cuboli,  run into a com-
 mon stock or root called  a Lactiferous Sinus.   These si-
 nuses are in all about fifteen, they are only a few lines long,
 and  differ in size, some not being larger than a lactiferous
 duct, while others have a diameter of from two to three
 lines.   The sinus at the end next to the nipple terminates
 in a sort of rounded  cul-de-sac; but  from  the extremity of
 the sac a very fine conoidal tube arises which runs through
 the nipple, and conducts the milk to its surface.  This tube
 from its shape is suited to  the retention of  milk; in addition
 to which it is sometimes dilated in the middle, is curved
 when the nipple is not in a state of erection or stretched
 out,  and terminates by an  external orifice, which  is so fine
 as to be seen with difficulty by the naked  eye.

  The excretory ducts of the breast, under which term may
be comprehended the lactiferous ducts, the sinuses, and the

  * Marjolin, Manual D'Anat. J. F. Meckel, Manual D'Anat.
  f Alex. Kolpin, Diss. Inaug. de Struct. Main. Cuboli, Append, ad Sep-
tcmd. Tab. S:mtorini.  Girardi,  Append, ad Scptemd. Tab. Santorini. 
118            THE LACTIFEROUS GLANDS.
conoidal tubes in the nipple, are formed by a soft, thin, and
semi-transparent membrane, very capable of extension and
of contraction.  The trunks generally go deeply through
the substance of the gland and are tortuous, but do not anas-
tomose laterally with one another; whence it happens that
the lobes and  lobules of the gland are arranged into sec-
tions, each of which has its  appropriated excretory duct.
In order to make a complete injection of the gland, each
sinus must be  separately injected through  its papillary
conduit.   This rule  is not, however, of universal applica-
tion, as in some experiments performed by the elder Mec-
kel upon women advanced in pregnancy and during lacta-
tion, he  succeeded in forcing mercury through one sinus,
by its ramifications,  into those of another; this route was
supposed to have been through the finest extremities of the
ducts.   The whole gland itself may,  however, from the
infrequency of this circumstance, and from the difficulties
and partial condition of these anastomoses, rather be consi-
dered as a congeries of smaller glands, kept distinct by the
interposition of cellular substance between their lobes; but
joined, in one respect, by having the terminations of their
excretory tubes collected into  one bunch in the  nipple.
This latter circumstance seems to be  only a provision for
the more convenient sucking of the infant.

  The excretory ducts are no where furnished with  valves,
which accounts for the facility with which they may be in-
jected backwards from the nipple.  An opinion was enter-
tained  by Haller,  and by other anatomists after him, that
some of these ducts originated  in the surrounding cellular
substance, but this has  been refuted  by the researches of
Cuboli.   Some anatomists have thought that there  is a di-
rect communication between the ends of the lactiferous tubes
and the arteries, veins, and lymphatics.  Mascagni, after a
very successful injection of the gland, whereby its vesicles
were filled with quicksilver, not  meeting  with such an oc-
currence, was induced to think that when the communica-
tion did happen, it was produced  by rupture. 
THE PAPILLA.
119
                      The Areola.

  In virgins is a rose-coloured circle, which surrounds the
base of the papilla or nipple.  In women who have borne
children, or in  those whose age is advanced,  it becomes of
a dark brown.  The skin of the  areola is extremely deli-
cate, and on its surface, particularly in pregnant or nursing
females, there are from four to ten tubercles, which some-
times form a regular circle near its circumference, and in
other subjects are irregularly distributed.  Each of these
tubercles has near its summit three or four foramina, which
are the orifices of the excretory ducts of a little gland form-
ing  the tubercle.  The areola consists  of a  spongy tissue
beneath which there is no fat; it is susceptible of distention
during lactation, or from particular excitement.

   The greater number of anatomists have considered  these
tubercles as intended only for the secretion of an unctuous
fluid which lubricates the areola and nipple, and protects
them from excoriation  by the sucking of the infant.   It is
said, however,* that  when some time has  elapsed after
a repast, or when there has been a long interval to the
nursing of the child, milk flows from them abundantly; but
that in inverse circumstances a transparent, limpid fluid is
distilled in small drops; all of  which would tend to prove
that they are of  the same nature with the mammae them-
selves,  being only smaller.  In addition to them, it is said,
that the areola and the  nipple are furnished with a great
number of sebaceous glands, which do not elevate themselves
above the surface, and which maybe found on and near the
tubercles.

                       The Papilla,

   Is the truncated cone in the centre of the mamma, of the
same colour with  the areola and surrounded by it.   The
lactiferous tubes terminate on its extremity.  It is collapsed
* J. F. Meckel. 
1JU
THE LACTIFEROUS GLANDS.
and in a very pliable state for the most part, but when ex-
cited  it swells, becomes more prominent, and of a deeper
colour.  Its skin is rough,  and provided  with  numerous
and very small papillae.  Its internal structure consists of
the extremities of the lactiferous tubes united by condensed
cellular membrane.
  The mamma is supplied  with blood from  the external
thoracic, intercostal, and internal mammary arteries.  Its
veins attend  their respective  arteries.  The nerves come
from  the  axillary plexus and  from the intercostals.  The
lymphatics run into the internal mammary, intercostal, and
axillary trunks. 
BOOK  VII.
Of the Organs of Respiration.
  The Organs of Respiration are the Larynx, the Trachea,
and the Lungs.
                     CHAPTER I.

                     OF THE LARYNX.

   The Larynx is an irregular cartilaginous tube, that forms
 the upper extremity of the windpipe.  It is situated imme-
 diately below the os hyoides and  the root of the  tongue,
 where it may be felt readily through the integuments, and
 by its prominence  contributes to the outline of  the neck.
 Its position is such, that it is bounded behind, by the pha-
 rynx,  which is  interposed between it and the vertebrae of
 the neck; and laterally, by the primitive carotid arteries and
 the internal jugular veins. It gives passage to the  air which
 is inhaled into the  lungs or  exhaled from them, and also
 contributes essentially to the  production of the voice.   Its
 special use, on the latter occasion, has induced some anato-
 mists to give it  a description apart from that of the other
 organs of respiration;  but, as the function of voice is subor-
dinate to that of respiration, I have preferred an ohs  r, ,n ,„
 of its most natural and local connexions.
  Five distinct cartilages form the skeleton of tr.i.s structure;
the  os hyoides, which is common to it and to the root of the
  Vol. II.—16 
122
ORGANS OF RESPIRATION.
tongue, also contributes  to its  superior part, in a manner
which  will  be presently mentioned.  The  cartilages are
one Thyroid,  one Cricoid, one Epiglottis and  two Aryte-
noid.

  The Thyroid  Cartilage  (Cartilago Thy raided)  is the
largest of the five, and being placed about one inch below the
os hyoides, produces in the upper part of the neck the promi-
nence called Pomum Adami. It consists in two lateral halves,
which in most individuals are perfectly symmetrical, and are
continuous with each other on the middle line of the body.
These two sides form at their line of junction an angle pro-
jecting forwards, and resembling that of the canal or hydrau-
lic gate; the superior part  of the angle is more prominent
than the inferior;  particularly in the male  subject.   The
sides of this body lean outwards, by which its transverse
diameter above is increased.
  The angle is  terminated above by a  deep notch, from
which the superior margin  begins to form a curvature, on
either  side, like the letter  S;  the inferior  margin is also
somewhat curved, but to a smaller degree.   The posterior
margin of each half is nearly straight, but is elongated above,
with the aid of  the  upper margin, into a long  process, the
Cornu Majus; and below, with the aid of the inferior margin,
into another process not so long, Cornu Minus.   By the
latter  the thyroid  cartilage  is articulated by  ligamentous
fibres called the lateral crico-thyroid ligament to the side of
the cricoid  cartilage, which thereby becomes the fulcrum of
many  of its motions.
   The internal surface of each  half of the thyroid cartilage
is flat;  but the  exterior surface  is  slightly marked by the
sterno-thyroid and the thyreo-hyoid muscles.

   The Cricoid Cartilage (Cartilago  Cricoidea) is placed be-
low the thyroid, and is the base of the larynx.  It is an oval
 ring, of unequal thickness and  breadth.
   Its inferior margin is nearly straight and horizontal, and
 is connected to the first ring of the  trachea; it is also thin-
 ner than the superior: the latter is  very oblique,  and rises 
THE LARYNX.
123
 from before backwards and  upwards so abruptly, that the
 breadth of the cricoid cartilage behind becomes three times
 as great as it is in front,  under the inferior margin of the
 thyroid cartilage.  The  superior margin has on each side
 behind, a little head or convexity,  which receives the base
 of the corresponding arytenoid cartilage, and forms with it
 a ball and socket joint.
    The interior surface  of the  cricoid cartilage is smooth,
 and covered by the lining membrane of the larynx.   Its ex-
 terior surface is flattened  on each side behind, by the poste-
 rior crico-arytenoid muscles; it is, marked  also laterally by
 other muscles, and by the  inferior cornu  of the thyroid
 cartilage.
    The cricoid cartilage is embraced by the inferior margin
 of the thyroid, but in such a way that a triangular interval
 is left in front between  the two cartilages.
   This interval is filled by a ligament adhering to its mar-
 gins called the middle Crico-Thyroid, to distinguish it from
 the ligamentous junction between the inferior cornua of the
 thyroid, and the sides of the cricoid.   The middle ligament
 has some small apertures in it, for the passage of blood ves-
 sels and of nerves.  It is the  part commonly cut in the ope-
 ration of laryngotomy.

   The Arytenoid Cartilages  (Cartilagines Arytaenoidese)
 resemble  triangular pyramids curved backwards, and about
 six lines long.   They are placed on the upper margin of
 the cricoid cartilage behind.  The anterior  face of each is
 uneven,  and divided  into two concavities; the posterior
 face forms a single cylindrical concavity; and the internal
 face,  by which it approximates its fellow, is  nearly flat.
 When joined together, the two cartilages resemble the mouth
 or spout of a pitcher, from whence their name.  Their bases
 are  hollowed into  a  small  glenoid  cavity, for articulating
with the cricoid cartilage.
  A synovial capsule is reflected over the articulation, be-
 tween the arytenoid and  the cricoid cartilage; this capsule
is strengthened by a few  scattered ligamentous fibres. 
124
ORGANS OF RESPIRATION.
  The Epiglottis Cartilage (Epiglottis) is situated on the
posterior face of the base of the os hyoides, being enclosed
partially by the two sides of the thyroid cartilage.   Its ge-
neral form is that of an oval disk; the upper margin of it
is thin and rounded, and the lower part is elongated into a
pedicle which adheres to the entering angle of the thyroid
cartilage.
  Its surfaces, though nearly flat, are not fully so;  for an-
teriorly, it forms a  cylindrical convexity, and posteriorly,
a cylindrical concavity, from side to side.  When nicely
stripped of its covering, a number of very small foramina
are seen to exist in  it, which give passage principally to the
ducts of  muciparous glands.  Its connexions, aided by its
natural elasticity, keep it in a vertical  attitude behind the
base of the tongue;  its rounded  margin  is elevated above
the latter and overlooks it.

  In addition to the preceding cartilages, there are always
two, and sometimes four others.   On the top of each ary-
tenoid  is to be found one, (Corniculum Laryngis;) it is some-
what triangular and elongated;  its inferior face is attached
by a few ligamentous  fibres to the end of the arytenoid; it
is included in the soft parts, and is very moveable.  The
others, when  they exist, are found on  the margin of the
glottis, in the duplicature of  the membrane which is ex-
tended from the side of the epiglottis to the tip of the ary-
tenoid  cartilage.

  From the whole superior margin of the thyroid cartilage
included between its greater cornua, there proceeds upwards
a thin  lamina of somewhat condensed  cellular  substance,
which  is attached to the posterior margin of the base and of
the cornua of the os hyoides their whole  length.  It fills
completely the space between the os hyoides and the thyroid
cartilage.   This membrane is called the middle Thyro-
hyoid  ligament, though its ligamentous  character is by no
means  well developed.  It completes the periphery of the
larynx in the space  alluded to, and, from its thin yielding 
THE LARYNX.
125
nature, presents no obstacle to the motions of the os hyoides
and of the thyroid cartilage upon each other.
  The posterior margin of this membrane, on each side,
is  bounded  by a long, rounded, fibrous chord, the Liga-
mentum Thyreo-Hyoideum Laterale.  The latter is extend-
ed from the cornu major of the thyroid cartilage to the tu-
berculated extremity of the os hyoides, and frequently con-
tains, about its centre, a small oval cartilage or bone, (car-
tilago triticea,) not quite so large as a grain of wheat.
   Immediately under the body of the os hyoides,  between
its concave  face and the middle thyreo-hyoid ligament, is  a
small sac formed between the laminae of the ligament, and
frequently extending itself downwards as far as the notch
of the thyroid cartilage; it is  flat, about  four or five lines
in its transverse diameter, and presents a shining surface.  I
have never seen a fluid in it  in the natural state; its secre-
tion, however, sometimes becomes excessive, and  it is then
elongated downwards over the front of the thyroid and of
the cricoid  cartilage, as far as the isthmus of  the  thyroid
gland.   In this state it frequently forms a small  fistulous
opening, at its lower end, through the skin, which is marked
by a fold of the latter across the neck.   The true pathology
of the disease was first pointed  out by Dr. Physick,  who
cures it, in some cases, by the introduction of lunar caustic,
and in others by extirpation.
   The  Thyreo-Arytenoid Ligaments are two in number,
on each side of the larynx; one above the other at the dis-
tance of three lines.   The inferior is extended from the an-
terior angle of the base of the arytenoid cartilage,  to the in-
ferior part of the entering angle of the thyroid, and by con-
verging towards its fellow, is inserted there in contact with
it.  Its fibrous  structure is very distinct.  It also bears the
name of Ligamentum Vocale, from its bordering the rima
glottidis.  The superior thyreo-arytenoid ligament arises
from the middle of the anterior edge of the arytenoid car-
tilage, and is  also inserted into the  entering angle of the
thyroid; it is more distant from its fellow than the lower
 one, and goes almost parallel with it;  so  that the opening 
126
ORGANS OF RESPIRATION.
  between the two, is both larger and more like an oblong.
  Its fibrous structure is less distinct than that of the lower.
  Both the upper and the lower ligaments are covered by a re-
  flection of the lining membrane of the larynx, and are small
  round fibrous threads, which are rendered more or less tense
  by the action of the small muscles of the larynx.

   There are several pairs of  muscles belonging to the la-
 rynx.

   1. The Thyreo-Hyoideus, as observed elsewhere, looks
 like a continuation of the sterno-thyroideus.   It arises ob-
 liquely from the side of the thyroid  cartilage by the ridge
 there, and running upwards it is inserted into a part of the
 base, and into nearly all the cornu of the os  hyoides.
   When the thyroid cartilage is  fixed, it draws down the
 os hyoides;  but when the latter,is fixed, it draws up the
 thyroid cartilage.

   2.  The  Crico-Thyroideus, arises  tendinous  and  fleshy
 from the anterior lateral surface of the cricoid cartilage, and
 passes upwards and backwards to be inserted into the infe-
 rior cornu of the thyroid cartilage, and the adjacent part
 of its inferior edge.   Use, to draw these cartilages oblique-
 ly together.

   3. The Crico-Arytenoideus Posticus, arises from the back
 of the cricoid cartilage, occupying its excavation, and  is in-
 serted into the posterior part of the base of  the arytenoid
 cartilage. It draws the arytenoid backwards, and makes the
ligaments tense.

   4. The Crico-Arytenoideus Lateralis, arises from the side
of the cricoid cartilage, and is inserted into the side of the
base of the arytenoid.   Use, to  draw the latter outwards,
and open the chink of the glottis.

   5. The Thyreo-Arytenoideus, arises from  the posterior
face of the thyroid cartilage near its angle, and the middle 
THE LARYNX.
127
crico-thyroid ligament, and is inserted  into the  anterior
edge of the arytenoid cartilage.  Use, to relax the ligaments
of the glottis.

   6. The Arytenoideus Obliquus, arises  from the base of
one arytenoid cartilage, and is  inserted into the tip of the
other.   It is a very small fasciculus,  and sometimes only
one muscle exists.  Use, to close the chink of the glottis.

   7.  The  Arytenoideus  Transversus  is always  a  single
muscle, which arises posteriorly from the whole length of
one  arytenoid cartilage, excepting a little part of  the tip,
and is inserted, in a corresponding manner, into  the  other.
It fills up the cylindrical concavity of the arytenoid carti-
lages.   Use, to close the chink of the glottis.

   8.  The  Thyreo-Epiglottideus, consists in  a few fibres,
and arises from the  posterior face of the thyroid  cartilage
near its entering angle.   It is  inserted  into the side of the
epiglottis.    Use, to draw  the epiglottis downwards.

   9. The  Aryteno-Epiglottideus consists also in a few in-
distinct fibres,  and arises from the superior lateral parts of
the arytenoid cartilage.   It is  inserted into the side of the
epiglottis.    Use,  to draw the epiglottis downwards.
   These two last muscles  are generally so small  and unde-
fined, that they cannot be satisfactorily distinguished from
the adjacent soft parts. *

   On the posterior face of the  thyroid  cartilage, of the thy-
reo-hyoid  membrane;  and on  each side of the epiglottis
cartilage, surrounding its lower part, with the exception of
its posterior face, there  is  an accumulation of cellular and
adipose substance. In the lower part of this substance there

  * A muscle of a triangular shape has lately been observed by the En-
glish anatomists, situated in front of the epiglottis, passing to it from the
base of the os hyoides; it is called Hyo-Epiglottideus.  The observations
on its existence have not yet been repeated sufficiently often to determine
whether it belongs to the normal structure of the body or not; and in my
own dissection, for the purpose of ascertaining its existence, it has not oc-
curred.  Am. Med. Jour. vol. v. 
128
ORGANS OF RESPIRATION.
are several small glandular bodies, sometimes insulated and
sometimes collected together, which detach their prolonga-
tions into the foramina of the epiglottis cartilage, and seem
to open thereby on its laryngeal surface; they are mucous
glands.
  The Arytenoid Gland, which is also muciparous,  is si-
tuated in front of the arytenoid cartilage, in the duplicature
of the mucous membrane which passes from the side of the
epiglottis cartilage to the arytenoid.   It is  a small body  of
a grayish colour, resembling the  letter L, and  consists  in
distinct grains; it is  supposed to have its excretory ducts
opening into the larynx.  It is frequently  Avanting.

   The interior face of the Larynx is lined by a mucous mem-
brane continuous above with that of the mouth and pharynx,
and below with that of the trachea.   Where it  is reflected
from the base of  the  tongue to  the  epiglottis cartilage,  it
forms as described, a well marked vertical  fold or fraenum
in front of the middle of the latter, and on  each side of this
middle fold there is another,  not so distinct, but varying
in different subjects.   The three folds form two pouches  in
front of the epiglottis, in which  food is sometimes lodged.
The mucous membrane also forms the duplicature on each
side already alluded to, which  passes from the lateral part
of the epiglottis cartilage  to the arytenoid of the same side
of the body.   This duplicature forms the superior bounda-
ry of the cavity of the larynx, and is very soft  and exten-
sible, permitting freely the epiglottis to be depressed and
to rise again into its vertical position.  The duplications
of the two sides,  taken together, form an oblong oval open-
ing into the larynx,  passing very obliquely upwards and
forwards to the epiglottis,  and terminated behind by a notch
between the cornicula laryngis.  At the latter place the mu-
cous membrane is wrinkled and loose, so as  to permit, by
its extensibility, free motion to the arytenoid  cartilages.
   After adopting the preceding arrangement,  the  lining
membrane  of  the  larynx  passes downwards; it covers
smoothly the  posterior face  of  the epiglottis, adhering 
THE LARYNX.
129
closely to it; but, when it reaches the thyreo-arytenoid li-
gaments, it is tucked in between the upper and the lower
one, so as  to form, on either  side, an oblong pouch, the
bottom of which is broader than  its orifice between the li-
gaments.   This pouch is the ventricle of Galen, or of Mor-
gagni, or of the larynx; it projects into the fatty glandular
matter on  the posterior face of the thyroid  cartilage, and
has its base resting on the thyreo-arytenoid muscle.  The
continuation  of the membrane afterwards lines smoothly the
cricoid cartilage,  and abounds there  in mucous follicles.
   That portion of the larynx which is formed by the thy-
reo-arytenoid ligaments, and the pouches  between them, is
the structure essential to the formation of voice.   The open-
ing between the two lower ligaments is the Rima Glottidis,
and the space between the upper ligaments and the duplica-
ture of the mucous membrane  passing from the arytenoids
to the epiglottis cartilage, may be termed  the Glottis.

   The Epiglottis cartilage is principally useful in prevent-
ing articles of food  from  falling  into the  glottis, either in
swallowing or in vomiting.  The strength of its muscles,
however, does not seem to be sufficient to draw it down over
the glottis, as many physiologists suppose; on the contrary,
I am  induced to believe that the glottis is  rather drawn up-
wards to it   If, on any occasion, it be depressed or bent
down  over the glottis, the position  must be caused by me-
chanical  pressure from the bulk of  the article swallowed.
But the latter explanation is not sufficient  to account for the
swallowing of fluids, or of a very small body, as a pill or
a crumb of bread.
   Impressed with these objections, and unsatisfied with the
common theory, I had an  opportunity, in a dissection a few
years ago,  of witnessing a position of these parts which af-
forded a satisfactory explanation.  The subject was a robust,
muscular man, who had died suddenly.   The upper orifice
of the glottis was closed and protected, but by an arrange-
ment precisely the reverse of the received opinion; for the
epiglottis,  retaining its naturally erect  position, with a
v   Vol. II.—17 
I3u
ORGANS OF RESPIRATION.
slight inclination backwards, had the opening of the glottis
drawn up so as to come in contact with its posterior face.
The cricoid cartilage, it has been mentioned, slopes on its
superior margin upwards and backwards; the front surfaces
of the arytenoid cartilages, in their natural position, are
nearly on a line with this slope, or a continuation of it; the
whole may therefore be considered in the light of an oblique
plane,  rising up behind the epiglottis cartilage.  By a very
slight additional elevation of this plane along with the rota-
tory motion of the thyroid cartilage  upon its lesser cornua,
the plane is caused to come in contact with  the posterior
face of the epiglottis, and thereby to close the upper open-
ing of the glottis.
   The principal agents in this motion are the thyreo-hyoid
muscles, the contraction of which,  causing  the  larynx  to
ascend, the opening of the glottis is  brought up behind the
epiglottis,  and thereby secured  from  the introduction  of
food into it.  Whether the food be passed from the mouth
into the stomach, as in swallowing, or from the stomach
into the mouth, as in vomiting, is equally unimportant; and
the security is the  same, whether the article be small or
large,  fluid or solid.   Several  years ago I dissected a gen-
tleman, who had symptoms of  sore throat with swelling of
the neck, superadded to those of pulmonary consumption;
during the  existence of his sore throat, in addition to the
usual difficulty  of  swallowing,  he was frequently affected
in the act, with strangulation to an alarming and distressing
degree.  In the dissection it was found  that an abscess,  of
considerable extent, existed between  the os hyoides and
the thyroid cartilage, and involved  the thyreo-hyoid mus-
cles.   Without knowing at the  time the value of  this ob-
servation, I am now persuaded that  the strangulation arose
from the inactivity of the thyreo-hyoid muscles.   In some
ulcerations of the epiglottis cartilage which I have had an
opportunity of seeing, the  upper circular portion, which
projects above the root of the tongue, has been lost; if the
accident be confined to that extent only, deglutition is not
much impaired, because still enough of the epiglottis is left
to perform the office assigned to it, as the upper part is less 
TRACHEA.
131
essential.   The  cases of its reputed loss by wounds, must
be considered as applying themselves to this upper portion
only, because a  wound low enough to remove the whole
body, would cause such a destruction of the rima glottidis,
as to produce an  embarrassment of respiration, incompati-
ble with life.
  It is probable  that  the inferior  constrictors of the  pha-
rynx, as well as the stylo-pharyngeal muscles, assist in this
use of the thyreo hyoidei.
  There is a well marked  difference in the larynx of the
two sexes.   In the female it  is generally smaller by one-
third than it is in the  male; the thyroid cartilage is also less
prominent, in consequence of  its two  halves uniting at an
angle more obtuse, the pomum adami  is therefore seldom
conspicuous.  The rima glottidis is also smaller in women.
  The nerves of  the larynx come principally from the su-
perior and the inferior laryngeal branches of the par vagum.
                    CHAPTER  II.

OF THE TRACHEA AND THE GLANDS BORDERING UPON IT.

                   SECT I.--TRACHEA.

   The Trachea, or Aspera Arteria, is a cylindrical canal of
four or five inches in length and about nine lines in  dia-
meter, communicating with the lungs for the transmission
of air.  It opens into  the larynx above, by being attached
to the inferior margin  of the  cricoid cartilage, and termi-
nates in the thorax,  opposite the third dorsal vertebra, by
two ramifications called Bronchiae.   In this course it is si-
tuated over the middle line of the neck, beneath the sterno-
thyroid  muscles, and  separated from them  by  the deep-
seated fascia of the neck and the adipose matter beneath it.
It is placed in front of  the oesophagus, between the primi- 
132
ORGANS OF RESPIRATION.
tive carotid arteries and the internal jugular veins.   When
it has got into the thorax, it inclines slightly to the right
side as it passes  behind the curvature of the aorta.   Of its
two branches, the right bronchia is larger .than the other; it
is also less slanting, and an inch long before it divides; it
sinks below the  right  pulmonary  artery, to penetrate the
lung about the fourth  dorsal vertebra.  The left bronchia
being an inch longer,  sinks  into the lung of the left side,
below the corresponding pulmonary artery and opposite the
fifth dorsal vertebra.   The bronchiae then divide and sub-
divide very minutely through the lungs.
  Very dissimilar structures enter into the composition  of
the trachea;  they are  cartilage, ligamentous fibre, muscle
and a mucous membrane.

  The Cartilage preserves the cylindrical shape of the-tra-
chea, and consists  in from sixteen to twenty distinct rings,
which are deficient in the  posterior third of their circumfe-
rence.  Each ring is about two lines  broad, and half a line
thick, and  is kept apart from the one above and below it by
a small interstice;  sometimes, however, they run into each
other.
  There is an almost uniform similitude between these rings;
the principal departure from which is observed in the first
being rather broader in front than  the others, and in the last
ring, which, by its corset-like shape in front, contributes to
the beginning of each bronchia.
  The rings of the bronchiae are, like those of the trachea,
deficient in their posterior third, and the same arrangement
holds during their primitive ramifications in the lungs.  But,
as they subdivide more and more, the cartilages do not suc-
ceed each other  so closely, are smaller segments of circles,
and are not  regularly  deficient at  the posterior third.   In
place of the latter, the whole periphery of the bronchial ra-
mification is cartilage, but the latter consists in several pieces
put end to end.  The pieces become, after a while, more and
more scattered and smaller, till they finally disappear.

  The Ligamentous Structure of the trachea and of the bron- 
TRACHEA.
133
chige is very evident between the proximate margins of the
cartilaginous rings, and fills up the intervals between them
so as to make the tube perfect.   This tissue may be traced
over the surfaces of the rings, forming their perichondrium,
so that they may be considered as imbedded in it.   It does
not exist, satisfactorily, in the human subject, in the interval
behind, where a third of the ring is defective, but in the bul-
lock it is there also.   In  the smaller ramifications of the
bronchiae, where a complete circle is formed by the juxtapo-
sition  of the several little cartilaginous segments, it is proba-
ble that this tissue contributes to the whole periphery of the
ramification.
   It possesses great elasticity, which is manifested by the
rapid shortening of the trachea, when its two extremities are
stretched apart and then suddenly let loose.  And it is the
continuance of this  quality  of elasticity, in the minute ra-
mifications  of the  bronchiae, which proves the existence
of this tissue there, even when  it cannot be very distinctly
seen.

   The Muscular Structure of the trachea exists at the carti-
laginous deficiency in  its posterior third, and consists in  a
thin muscular plane  whose fibres pass transversely between
the interrupted extremities of the cartilaginous rings of the
trachea and of the bronchiae.  These  transverse fibres begin
at the first  ring, and exist all the way down to the lungs:
they arise from the internal faces of the rings, and the in-
termediate  elastic ligamentous tissue; about a line beyond
their extremities.  Anteriorly, they are covered by the lining
membrane of the  trachea, and posteriorly by cellular tissue.
   In the lungs, where the cartilages become  scattered and
irregular, the muscular fibres are said, by J. F. Meckel, and
by M. Reisseissen,* to perform the whole  circuit of the

  * De Fabrica Pulmonis. Berlin, 1822.  M. Laennec says (Traite, de
l5Auscultation, Paris, 1826, vol. 2. p. 189,) that he has sought in vain to
verify these observations of Reisseissen, but that the manifest existence of
circular fibres upon branches of a middling  size and the phenomena of
many kinds of asthma, induce him to  view as a thing well established,
the temporary occlusion  of the small bronchial ramifications, by a spas-
modic contraction of their parietes. 
134
ORGANS OF RESPIRATION.
 bronchial ramification, and to be visible  even beyond the
 existence of the cartilaginous pieces.  Soemmering expresses
 a doubt of this arrangement.*  It is very difficult, in such
 minute structure, to arrive at a satisfactory conclusion. Lon-
 gitudinal fibres are also said  by  Portal  to  exist between
 the contiguous margins of the cartilaginous  rings, but the
 fact is far from being well ascertained, t
   The  use of this muscular tissue has been pointed out, for
 the last seven or eight years by  Dr. Physick, as follows:
 In expectoration, it diminishes the calibre of the air tubes,
 so that the air having to pass out with increased rapidity
 through them, its momentum will bring up the inspissated
 fluid which may be in its way.   This very ingenious theory
 has subsequently been advanced by M. Cruveilhier, of Paris,
 possibly without a knowledge of his having been anticipa-
 ted; but certainly not without the claims of the eminent in-
 dividual to whom we owe it, having been established by its
 publication. J
  The Mucous Membrane of the trachea lines its whole in-
 terior periphery, from the larynx  to the  bronchiae, and is
 continued, under the same circumstances, through the latter
 to their minute  divisions.   It adheres  very closely to the
 contiguous  structure, and  is continued,  in the substance of
 the lungs, beyond the traces  of any of the other tissues
 which compose the trachea;  it indeed terminates in the air
 cells.   It is thin, reddish, and presents an  abundance of
 slightly elevated longitudinal folds; one of the latter,  con-
 spicuous for its greater size, exists at the commencement of
 the left bronchia and is  yet  more developed in  the still-
 born infant.
  The  exterior circumference of the mucous membrane is
studded with muciparous glands, about the size of millet seed.

  * Extimae autem vel posticse ejus fibrae per longitudinem, a cartilagine cri-
coidea ad pulmones usque descendunt, ac vel in ipsis tracheae ramis haud pa-
rum conspicui sunt.—De Corp. Hum. Fabrica.
  | Portal. Anat. Med.
  i Wistar's Anatomy, 3d edition, vol. ii. p. 64. Phil. 1821. 
THE THYROID GLAND.
135
These glands are particularly conspicuous and abundant on
the posterior part of the trachea and of the bronchiae, where
the deficiency of the cartilaginous rings is supplied by the
membranous structure only; and more of them exist at the
lower part of the trachea and upon the roots of the bronchiae
than elsewhere. They are placed behind the muscular layer,
which their excretory ducts have to penetrate. Besides oc-
cupying  these situations, they are found in the interstices
between  the cartilaginous  rings, but  here they are much
smaller.  The mucous membrane  abounds so much in the
orifices made by their excretory ducts, that it looks cribri-
form, which appearance is increased by floating it in water.
  About the origins of the bronchiae, there is a considerable
number of black coloured  lymphatic glands, called Bron-
chial, which it is  easy  to distinguish from  the preceding
by their  colour and much greater size.

  There are two more glands of a different character, which,
though they do  not enter  into the composition of  the tra-
chea, yet, from their locality, are most conveniently studied
at this time: they are the Thyroid and the Thymus.
           SECT. II.--OF THE THYROID GLAND.

   The Thyroid Gland (Glandula Thyroidea) is placed on
the first and second rings of the trachea, and on the sides of
the larynx.
   It consists in a middle portion, which is thin, of variable
magnitude in different individuals, sometimes entirely want-
ing, and which, being stretched across the upper part of the
trachea just below the larynx, is called its isthmus;  and  of
two lobes, one on each  side,  which, being flattened and
ovoidal, are extended upwards on  the side of the larynx,
and downwards on the side of the trachea and of the oeso-
phagus. Frequently from the superior part of the isthmus,
and most commonly on its left side, a small pyramidal pro-
cess runs upwards in front of the cricoid and of the thyroid
cartilage, and  is attached, by ligamentous fibres to the os 
136
ORGANS OF RESPIRATION.
hyoides; this process, however, varies much in its size and
length; I have never  seen it double.   According to Mor-
gagni and Meckel, its existence is much more common than
its absence, which corresponds with my own observations.
The thyroid gland, when  extended, measures  about three
inches from side to side.
   It is covered in front by the  sterno-hyoid and thyroid
muscles, and  laterally  by the omo-hyoid and the  sterno
mastoid.  Embracing the  trachea and  the sides of the la-
rynx, its lobes repose upon the primitive  carotids, and the
internal jugular veins.
   The thyroid gland has a capsule which  is not very easily
raised up, but serves to give it a polish; it is also invested
by the condensed cellular membrane of the part called fas-
cia profunda.  Its surface is smooth and uniform.  It is of a
dark brown colour.  When cut into or torn, it is seen to
consist of several lobules adhering to each other: but  this
arrangement is not very distinct  except in an enlarged or
diseased state; and may be traced most easily by following
the course of the large blood vessels, which pass in the  in-
terstices between the  lobules.  The  latter  contain  many
small vesicles, or cells, filled  with a transparent or yellow-
ish and somewhat unctuous fluid; the cells  are frequently in
a collapsed state, which prevents them from being manifest
to the naked eye.
   There are four considerable arteries which supply  this
body, two on each side, one  coming from the external ca-
rotid and the other  from  the subclavian.   The veins  fol-
low the course of the  arteries for the  most part.   Bichat
has made a very interesting  remark on the  subject of its
blood vessels;  that, notwithstanding their  size and number,
and minute ramifications in it, much less blood remains in
its capillary system than in that of the liver or kidney, as
is proved by the quantity of water it tinges in maceration;
he therefore infers that the capillary system is less abun-
dant.
  Anatomists have sought in vain for one or more excre-
tory ducts to this body, and some have imagined that they
had found them terminating in the trachea,  or in the larynx. 
THE THYROID GLAND.
137
Santorini considered the pyramidal process from the isth-
mus as the desired duct.   The emphysema with which the
gland has sometimes  been affected  was supposed  to  be a
proof of its communicating with the trachea  by excretory
tubes; but it is more probable that the air was forced into
the cellular substance, uniting its lobules, and not into the
structure itself of the gland.  The settled opinion now seems
to be, that whatever fluid it secretes is conveyed away by
the lymphatic vessels.   Meckel has suggested, that as this
gland is more voluminous proportionately in early infancy,
particularly  its pyramidal process, possibly the  duct may
be obliterated when the gland begins to be restrained  in its
growth; but  if  this were the case, the duct ought  to  have
been found during the period indicated.   The probability
is, that it is a diverticulum of blood from the salivary glands
during the intermittence of their, action; and from the marked
sympathy between it and the brain in goitre, it may exercise
a corresponding function on this organ during its intervals
of repose.
   Duverney* has  described a small azygous muscle on the
middle line of the body, coming from the under margin of
the base of the os  hyoides, and running over the middle of
the thyroid cartilage, to be inserted into the upper margin
of the isthmus of the thyroid gland. Soemmering calls it Le-
vator Glandulae Thyroideae, and speaks of it as being found
more  frequently on the  left side,  and about half of  the
breadth of the thyreo hyoideus.   After many special exami-
nations for it, I have found it  in but very few instances, I
therefore consider it rare;  though without a close attention
to structure,  the  pyramidal process of the isthmus of  the
gland may, from the similitude of colour  and position, be
very readily mistaken for it, which I have reason to believe
is frequently  the  case.t  Some few fibres are often found
  * Essai D'Anatomie en tableaux imprimes, pi. IV.  Paris, 1745.
  f The unassisted eye, in a strong light, is generally sufficient to  deter-
mine the structure; but in case of doubt, by boiling the gland, if there be
muscular fibres along this process, their longitudinal and parallel direction
will become evident: they also may then be torn asunder, so as to be made
still more distinct; whereas the vesicular structure of the gland is not sus-
ceptible of division into fibres.
   Vol.  II.—18 
138              ORGANS OF RESPIRATION.

going to the isthmus of the gland from the crico-thyroid,
and the thyreo-hyoid  muscles, or from the thyroid carti-
lage.
           SECT. III.--OF THE THYMUS GLAND.
  This body (Glans Thymus) is placed between the tra-
chea and the upper extremity of the sternum.   It is irre-
gularly triangular,  its broadest part being above, and the
narrower below.  In the adult it is  in a collapsed and shri-
velled state, and scarcely presents a vestige of what it once
was; it is,  therefore, only in the infant that it can be satis-
factorily studied.
  At birth it  is  much larger, not relatively, but actually,
than it is  in the adult, and extends  from the body of the
heart up to the thyroid gland.   It is of a very soft consist-
ence and of a pink colour.   It is surrounded by a capsule
of cellular substance,  which,  when  removed, permits the
o-land  to  be resolved into  two lobes, one on either side,
which adhere to each other.   These lobes may be separated
with facility into lobules, and contain a whitish fluid.
  It is visible in the third  month of gestation,  and  conti-
nues to grow till the end of  the second year of extra-uterine
life.   It then collapses, and its structure is effaced about the
twelfth year; its remains are scarcely distinguishable sub-
sequently from the surrounding cellular substance.   No ex-
cretory duct has been found for it, and, though it clearly be-
longs to foetal and infantile existence, its use is problematical.
The probability  is, that it  is a diverticulum of blood from
the lungs during their state of quiescence in foetal life, and
until their structure becomes confirmed and proportionately
evolved.
                    CHAPTER  III.

                     OF THE LUNGS.

  The Lungs (Pulmones) are the essential seat of the pro-
cess of respiration, and occupy the greater part of the ca- 
THE LUNGS.
139
 vity of the thorax, as formed by the ribs and the intercos-
 tal muscles on the sides, by the sternum and its cartilages
 in front, by the dorsal vertebrae behind, and  by the dia-
 phragm below.   They are two bodies, placed one on either
 side of the thorax, and separated from each other by the heart
 and its great vessels.   As the heart  is the only organ of
 much volume which  is also included in the cavity of the
 thorax; the size of the lungs is in a direct relation with the
 capacity of the latter, and may therefore be known  by the
 external indications in the living body.   It is probable that
 there is  no void, or only a very small  one, between the
 sides of the lungs and the sides of the thorax.
   Each lung forms an irregular cone, the apex of which is
 above, and the base below; the latter,  from resting upon
 the diaphragm,  is, consequently, oblique from before back-
 wards and downwards, and  is also concave.   The surface
 which reposes against the periphery of the side of the tho-
 rax is uniformly rounded, but that which  looks towards
 its fellow, is concave, from being pressed in by the heart.
 From the  oblique direction of the diaphragm, the vertical
 diameter  of the lung behind,  when it is fully distended,
 goes from  the first to the last rib, and is consequently much
 more considerable than the vertical diameter in front, which
 extends  only from the first  rib  to the inferior end  of the
 second bone of the sternum, or,  in other words, to a level
 with the tendinous centre of the  diaphragm.
   The left lung is divided into two lobes by a deep fissure,
 which begins behind, on a level with the fourth  dorsal ver-
 tebra, and runs  obliquely downwards  and forwards to the
 anterior margin of its base.  A deep fissure in a nearly si-
 milar situation is observed on the right lung;  but from it
 another fissure branches out  forwards, by which the right
 lung is divided into three lobes.   The internal face of the
left lung it also rather more concave than that of the  right,
from the apex of the heart projecting into it.   The right
lung is more voluminous than the left, which corresponds
 with the greater size of the bronchia on  this side, but its
vertical diameter is not so great, from  the pressure of the
liver from below. 
140
ORGANS OF RESPIRATION.
   Near the middle of the internal face of each lung are to
 be seen the points of connexion with the bronchia, and with
 the pulmonary vessels.   Before these the anterior margin
 is thin, and more or less winding where the lung is intro-
 duced between the heart and the front parietes of the tho-
 rax.   When the lungs  are fully inflated, but  a very small
 portion of the pericardium can be seen here between them.
 The posterior margin is thick,  and rounded where  it rests
 against the.vertebral column.
   The whole rounded circumference of the lung as  well as
 its base, though they  are in contact with the parietes of the
 thorax, do not adhere at any point to them. The connexion
 of the lung by which it is maintained in its situation, is en-
 tirely on the side of its concave face, where the pulmonary
 vessels and  bronchia enter, and though other attachments
 are frequently found  springing from different points of the
 thorax, they are purely  the results of disease.

             Of the  Texture of the Lungs.

   Each lobe of the lungs is divided into a great many dis-
 tinct lobules, which adhere together by intermediate cellu-
 lar tissue.   The marks  of these divisions are  apparent on
 the surface  by lines  running in  different directions,  but
 they are made still  more distinct by tearing them asunder,
 This connecting cellular substance may be inflated through-
 out by a blowpipe introduced at any point of it.  These lo-
 bules are  again  subdivided  into very fine air  cells, which
 may  be  considered as  the terminations of the ultimate
 branches of the  bronchia.  The cells do not communicate
laterally with one another,  as the  cells of the bones,  but
only with the ramifications of the bronchia, to which they
respectively belong.
   Besides the ramifications of the bronchiae,- the substance
of the lungs is  composed of numerous blood vessels and
lymphatics,  and  is well supplied with nerves.
   The blood vessels are  of two  kinds,  the pulmonary and
the bronchial.   The pulmonary artery, coming from  the
right  ventricle of the  heart,  divides under the arch of  the 
THE LUNGS.
141
aorta into two large branches: one for the right lung, and
the other for the left.  The right branch is larger than the
left.  Each of these branches having reached the upper
part of the root of its respective lung, begins there to dis-
tribute itself in large trunks, which  divide and subdivide
throughout  the substance of the lung.  The terminating
branches finally become  capillary, and  ramify in the pari-
etes of the fine cells, where the blood which they carry, from
being dark-coloured  and venous, is so altered as to have the
arterial qualities restored to it, and to become of  a bright
red. From the ultimate branches of the pulmonary artery,
arise the first branches of the pulmonary veins.   These are
successively accumulated into two  large  trunks  on each
side, which, issuing at the lower part of the root of the lung,
go to open  into the left auricle of the heart.  It has  been
remarked by Mr. Boyer that the two pulmonary veins are
less capacious.than the pulmonary artery of the same side,
in which  they manifest a peculiarity, differing from what
exists in other parts of the body.  The pulmonary artery
and veins are distributed in company with  the_ bronchia.
From the observations of Professor Mayer, it appears that
valves exist in the pulmonary veins, contrary to the gene-
ral opinion of anatomists.   They are found where smaller
trunks join the larger ones,  at an acute angle, but there are
none when they join at  a right angle.*
   The second order of blood vessels, being  the bronchial,
also consists in arteries and in veins, and belongs to  the nou-
rishment of the lungs.   They  too attend the branching of
the bronchia.   The  arteries pervade the substance of the
lung by innumerable fine  branches,  and anastomose with
the  pulmonary arteries.   The bronchial veins also anasto-
mose with  the pulmonary veins, but finally come out in
small trunks from the root of the lung, and empty  into the
vena azygos.
   The Lymphatics of the lungs are numerous; after tra-
versing the black bronchial glands,  those of the  left side
empty into  the thoracic duct, and those of the right into the
* Am. Med. Jour. vol. iii. page 186. 
142            ORGANS OF RESPIRATION.
large lymphatic trunk  coming from the right upper extre-
mity.
  The Nerves come principally from the par vagum.  Some
of them are distributed along with the bronchia, and may
be traced to the mucous membrane; others seem to be more
specifically appropriated to the vessels.
  It will now be understood that the root of each lung is
formed by the pulmonary artery, the two pulmonary veins,
and the bronchia, covered  by the pleura where the  latter
extends from the lung  to the pericardium.  The relative si-
tuation is  such that the pulmonary artery is above, the bron-
chia in the  centre  and behind,  and the pulmonary veins
below.
  The  lung of the adult  is of alight pink colour, with
specks or patches of black; in early life there  is much less of
the latter, and in advanced life it becomes more  abundant.
  The texture of the  lung is  so light and spongy after an
animal has once breathed, that its weight is very inconside-
rable when  compared with its volume.   Its cells  are  left
much distended,  even  when the animal is dead, and not-
withstanding, from its  unusual elasticity, it  expels a great
quantity of air when the thorax is opened, and is  thereby
reduced to a third of  its  size during life,  yet  it retains
enough air to make it float in water, or even in spirits of
wine.   The quantity of air which the lungs  contain differs
very considerably in different individuals,  depending  en-
tirely on the capaciousness of the  thorax.   Its medium
amount is computed at one hundred and forty-five cubic
inches; thirty cubic  inches of which are changed at every
act of respiration.

                    Of the Pleurae.
  Each lung has its covering called pleura.  This membrane
is reflected from the internal surface of the lung to the ad-
jacent side of the pericardium, and is then spread over the
interior periphery of that half of the thorax to which it be-
longs, lining the ribs and intercostal muscles, and covering
the convex face of the diaphragm.  There are, therefore,
two  pleurae, each of which, is confined to its  appropriate 
THE LUNGS.        '           143
half of the thorax, lining its cavity and covering its lung.
The Pleura, like other serous membranes, is a thin membra-
nous sac.  Its circumference is entire, like that of an inflated
bladder, there is therefore no point or line at which one may
preferably begin  an account of its course and attachments.
To commence, however, at  the  sternum; the pleura goes
thence outwardly to line the lateral parietes of the thorax,
as formed by the cartilages of the ribs, the ribs themselves,
and the intercostal muscles.  In  this way it may be traced
around to the dorsal vertebrae, and over the convex surface
of the diaphragm.  In proceeding along the first  rib, which
is very oblique,  it forms a sort of bulging bag, which pro-
jects  towards the trachea,  lines the lower part of the scale-
nus anticus muscle, and receives the upper extremity of the
lung.  The  pleura having  reached  the  dorsal  vertebrae,
passes from their sides  forwards, to the posterior  part of the
pericardium, a very small portion  of which it covers.   It
then goes upon the posterior face of the pulmonary vessels
and of the bronchia to  the lung; and applies itself closely to
the latter.  It then covers the part of the lung posterior to
the pulmonary vessels, and  continues to advance along the
rounded surface of the lung, to its anterior margin: it then
 passes over the internal surface of the  lung,  which is ante-
 rior  to  the  pulmonary vessels.  It afterwards  covers the
 front of the pulmonary vessels and of the  bronchia, and
 gets  in a very  short  space to the pericardium.  It then
 passes forwards on the side of  the  latter, and  having got
 near its middle  line,  goes from  it to the  sternum,  and
 reaches the line from which the  description of its course
 commenced.
    There is no important difference between the two pleurae
 either in their mode of reflection or in the organs to which
 they are attached, so  that the description of one will apply
 to either.  The portion of each pleura covering the lung is
 called pleura pulmonalis, and that portion which lines the
 thorax is the pleura costalis.  A duplicature of the pleura
 commences at the inferior margin  of the pulmonary veins,
 and  descending as far as the diaphragm, attaches the infe-
 rior portion of the posterior margin of  each lung to the side 
144
ORGANS OF RESPIRATION.
of the pericardium in front of the vertebrae.   This duplica-
ture is the Ligamentum Pulmonis.  It is longer on the left
lung than on the right by reason of the greater vertical
diameter of the former.
  From what has been said it will now be readily under-
stood, that the whole cavity of the thorax is divided verti-
cally into two halves, by that  portion  of the two pleurae
which advances from the spine towards the sternum.  This
septum is called the Mediastinum, and the heart, enveloped
by the pericardium, is placed precisely in its  centre, and
separates the two pleurae widely apart.  It has been found
useful by anatomists, for descriptive purposes, to subdivide
the Mediastinum into three portions or regions.   One pass-
ing from the front of the  pericardium to the posterior face
of the middle line of the sternum is the Anterior Mediasti-
num; another passing from the posterior face of the peri-
cardium  to  the  dorsal vertebrae is the Posterior Mediasti-
num; and a third, which  is within the circuit of the first
ribs, is the Superior Mediastinum. This division, though
evidently forced and arbitrary, is indispensable to a correct
account of  the relative  situation of very important organs
placed between the two pleurae.

  1. The Anterior Mediastinum is less important than the
other two; the portions of the two pleurae of which it con-
sists are almost in contact, and contain between them some
loose cellular substance by which they adhere together, and
by  cutting through which, after a longitudinal section of the
sternum, they are easily separated from one another.   The
upper part of this septum contains the remains of the thymus
gland, its lower part leaves the middle line  of the sternum
and inclines to the left side; and when the sternum is nar-
row below, it is  attached to the anterior ends of the carti-
lages of the lower true ribs.

  2. The Posterior Mediastinum, where it leaves the verte-
brae to reach the  pericardium, passes  off from a line nearer
the heads of the  ribs on  the left  side, than on  the right.
The descending  portion of the  thoracic aorta is contained 
THE LUNGS.
145
 within this septum, on the left side of the dorsal vertebrae.
 The  oesophagus is in its middle in  front of the vertebrae
 above, but in descending it crosses in front of the aorta, and
 inclines  to the left side of the dorsal vertebra?.  The  vena
 azygos occupies the right side of this mediastinum, and after
 ascending forms an arch over the root of the right lung, and
 terminates by joining the  descending cava.  The thoracic
 duct, after entering  the thorax between  the  crura of the
 diaphragm, ascends in front of the dorsal vertebrae between
 the aorta and  the vena azygos, and behind the oesophagus,
 till it reaches the  third dorsal vertebra; it then inclines  to
 the left side, and  mounting  into the  root of the neck near
 the vertebrae, it finally forms an arch, which, by advancing
 forwards, terminates in the angle formed by the junction of
 the left internal jugular and subclavian veins.   The par Va-
 gum  Nerve, of both sides, is also in the posterior medias-
 tinum.

   3.  The Superior Mediastinum is bounded in  front  by the
 upper part of the sternum, behind by the upper dorsal ver-
 tebrae, and laterally by the first ribs.   The cavity is conoi-
 dal, with the base upwards, but  is too peculiar to admit  of
 a rigid comparison with any thing else.   The pleura are
 reflected  downwards from the internal edge of the first ribs
 not abruptly, but  in  a rounded bulging manner, receiving
 there, as  mentioned,  the tip or apex of the lungs. In order
 to understand well the position of the pleurae, it must be
 borne in mind  that the upper rib is placed very obliquely
 downwards and forwards, at an angle of about forty-five
 degrees with the spine, consequently the  pleura, in being
 reflected  from  its whole internal edge, is  much higher at
 the head of the rib than it is at the anterior  extremity of the
 same.  This cavity is continuous of course with that of the
 anterior  mediastinum in front,  and also with  that of the
 posterior mediastinum behind.
  The remains of the thymus  gland are where this cavity
joins the anterior mediastinum; a part  of the gland is indeed
 in each of these cavities just below the transverse vein. In
 contact with the right pleura is the Descending Vena Cava
  Vol. II.—19 
146
ORGANS OP RESPIRATION.
The common trunk of the Left Subclavian, and Internal
Jugular, called the Transverse Vein, or Vena Innominata,
after crossing in  an  oblique descent behind the upper por-
tion of the sternum, joins the descending cava an inch above
the place where the latter penetrates into the pericardium.
Behind  the transverse vein are the top of the arch of the
aorta, the arteria innominata, the left carotid, and  the left
subclavian.  The trachea, with the oesophagus behind it, de-
scends along the middle line in front of the spinal column.
The arteria innominata crosses the front of the trachea from
left to right in ascending; it is  in contact with  the transverse
vein,  and more superficial than either of the other arteries.
The phrenic nerve, passing at the internal edge of the sca-
lenus  anticus, between the subclavian artery and vein, de-
scends vertically in contact with the pleura. The par vagum
passes along the side of the trachea, and afterwards behind
the corresponding bronchia having got into the superior
mediastinum, between the subclavian vein and artery: its
inferior laryngeal branch encircles the subclavian artery on
the right side, and the arch of the aorta on the left.

  The internal surface of the pleura is smooth and polished,
and is moistened and kept lubricated by an unctuous serum,
the natural quantity of which  is  merely sufficient to allow
the parts to  slide freely upon each other.  In  dropsy of the
chest  it  is augmented frequently to such an amount as to
cause  the collapse of the lung,  by pressing upon  it.
  In the cellular tissue between the pleura and pericardium,
as well as on the diaphragm, adipose matter, in considerable
abundance, is  found in corpulent persons advanced in  age.
  The blood vessels of the pleura costalis are derived from
those  which supply the parietes of the thorax, as the inter-
costals and phrenics.   They ramify in the subjacent cellu-
lar substance. 
BOOK  VIII.
          OF THE CIRCULATORY SYSTEM.

                        PART I.

  Of the General Anatomy of the Circulatory System.


                     CHAPTER I.

               GENERAL CONSIDERATIONS.

  The Circulatory,  or the Vascular System, consists in a
congeries of tubes, or cylindrical canals, which  convey the
blood to  and from every part of an animal body, and there-
fore enter into the texture or composition of almost every
portion of it.   In all animals  there seems  to  be a neces-
sity for the alternate reception and discharge of alimentary
materials; in the higher orders, this is effected through the
agency of the vascular system; but in the most  simple ani-
mals this system does not exist, and their whole fabric
being soft and permeable, nutritious matter is  introduced
by a direct absorption, or a species of capillary attraction,
after the  manner of a sponge or any other porous body, and
is discharged by a process equally simple/6  It  is probable
that there are some parts of the human body whose mode
of nutrition is equally simple; as, for example, the articular
cartilages, the hair, nails, and soon; for many observations
tend to prove that all these organs have an interstitial cir-
culation.

          * Hunter on the Blood.  Beclard, Anat. Gen, 
148
CIRCULATORi" SYSTEM.
  In many animals, the blood is propelled from a central
point, called the heart, to all parts of the body, and then re-
turns again to the heart.  The first  movement is executed
through canals called arteries, and the second through veins.
It is the most simple scheme by which a circulation can be
carried on through a sanguiferous system, and requires a heart
with only two  cavities; one  for propelling blood  into the
arteries, or departing tubes, and another as a reservoir for
receiving the blood of the returning tubes, or the veins.  The
two cavities must  be  near each other, and have a valvular
opening between them, which will permit the blood to  pass
from the venous into the arterial reservoir; but not from the
arterial into the venous.  A circulation of this simple cast is
found in fish and in animals generally, whose respiration is
effected on the surface of the body; but in man and in other
warm blooded animals, where respiration is carried on in-
teriorly by means of the lungs, their  circulatory apparatus
is double; one part being for the lungs, and the other  part
for the body generally.
  In man, the  heart  consists  of  four cavities: two auri-
cles or reservoirs of venous blood, and two ventricles  into
which the venous blood is  transmitted, and which in their
functions, may be compared to the forcing pump of a fire-en-
gine.  The circulation is effected in the following manner:
The blood contained in the right auricle of the heart flows
into the right ventricle, and from the latter  it is forced
through the  pulmonary artery into  the lungs.  It returns
from the lungs through the four pulmonary veins, and is re-
ceived into the left auricle of the heart; from the latter it
flows into the left ventricle, and is propelled from it into the
aorta.  The aorta then distributes it through the whole body
by  an infinitude of small branches; from the latter it is col-
lected, by corresponding veins, into two trunks, the Ascend-
ing and the  Descending Cava.   The ascending vena  cava
brings the blood from the lower extremities and from the ab-
domen; the descending vena cava brings the blood  from the
head and neck, the upper extremities, and the parietes of the
thorax.  These two trunks finally discharge the blood into 
GENERAL CONSIDERATIONS.
149
the cavity from which  it started, to wit, the right auricle.
The same round is then renewed, and continues to be repeat-
ed during the whole course of life.  It is customary for ana-
tomists to call  the rout of blood from the right ventricle,
through the lungs, to the left auricle inclusively, the lesser
or the pulmonary circulation; and that which begins at the
left ventricle, goes through the whole body, and ends in the
right auricle, the greater circulation.
   The blood contained in the veins of the greater circulation,
in the right auricle and ventricle, and in the pulmonary ar-
tery, is of a  dark brown or reddish colour; while that con-
tained in the pulmonary veins, in the left auricle and ventri-
cle, and in the aorta and its ramifications, is, from being vi-
vified by respiration, of a carmine or vermillion complexion.
The  celebrated Bichat  has, upon these differences of colour,
founded his division of  the whole circulating system into two
parts;  one containing black blood,  "Systeme  vasculaire a
 sang noire;" the other red blood, " Systeme vasculaire a sang
 rouge."   This division  having  general physiology for its
 object, affords a well marked distinction, suited to such dis-
 cussions.
   The lymphatics also are a part of the circulatory system,
 but as they  do not commonly convey red blood, the consid-
 eration of them will be brought up subsequently.  " They
 take a very active part in the animal economy,  whether na-
 tural or diseased, and  seem, in many actions, to be the anta-
 gonists of the  arteries; while the veins are much more pas-
 sive, being  principally employed in returning the blood to
 the heart."*
   The largest vascular trunks are situated near the centre of
 the body and limbs, on the side upon which flexion is accom-
 plished,  while those near the surface are generally small.
 Most commonly there  are one artery, one or two veins, and
 several lymphatics, all together.
   The arterial system  in its external configuration may be
 compared to  a tree, the trunk of which is attached to the
 heart, and which by a  continued succession of divisions and
* Hunter, loc. cit. 
150
CIRCULATORY SYSTEM.
subdivisions reaches to every part of the body.   There are
no  means of estimating rigidly the collective area of the
branches in proportion to that of the trunk, but  a little ob-
servation 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 im-
mense 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 to 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 cir-
culation is retarded both by additional friction and  by having
to fill up a larger canal.  The course of rivers exemplifies
this continually, while  confined to narrow channels  they
rush tumultuously through them, but when they begin to ex-
pand themselves into capacious basins, or to be divided into
a multitude of smaller channels, the current becomes slower,
and in some cases imperceptible, though the fact is clear,
that an equal volume of water is every where descending in
the same period  of time.
  The moisture  conferred upon all parts by the circulation
of the blood, bears  a sufficient analogy to the effects of ir-
rigation upon ground.   The water may be conducted to the
latter by a canal, which is finally divided into an infinitude
of streamlets, which 'ramify every where, and from the po-
rosity of their beds permit  lateral percolation, so  that the
whole field, even to its most minute atom,  is kept moist-
ened.    The  streamlets  afterwards successively assemble
again  into a single canal, which bears off their superabun-
dant water.   From the  nature of the particles  of blood,
many of them are confined  to their proper channels and
can never pass off by percolation  into the tissues, through 
GENERAL CONSIDERATIONS.
151
which the blood vessels ramify.   This may be proved by
the fact that the red  globules of blood have a diameter of
from the two-thousandth to the five-thousandth part of an
inch,  a size inconsiderable  as it is, yet too large to permit
their flowing through elementary fibres or atoms; whereas
serum or the water of the blood  may, from the  extreme
fineness of the particles, be  absorbed  by any tissue what-
ever; a circumstance  entirely unquestionable,  both from
daily observation,  as for example, in  soaking a  piece of
dried meat or a bone; and from the reflection that the air it-
self, will hold a certain quantity of water in solution.
   A question then arises whether the moisture of parts not
supplied with red globules of blood, comes in  the living
body exclusively from infiltration or from a peculiar set of
vessels called exhalents, often talked  of, but as yet never
seen ? That the lateral porosities of blood vessels are large
enough to  allow watery fluids  to  exude, is readily proved
by injecting  water into the  blood vessels of a limb, or of
any other part, when the latter invariably becomes ©edema-
tous.   It is in this way even  possible to inundate a living
animal, as I have  seen accomplished by M. Magendie, in
Paris.  This moisture requires a change, and by continued
additions would become  superabundant:  as  it has been
thrown out of the  common  current of the  circulation and
could not be removed in any other way, the lymphatic sys-
tem has therefore been added for the purpose.  In the low-
er orders of animals,  who are destitute of blood vessels, the
interstitial change of moisture goes on without lymphatics.
No part of the human body is exempt from moisture, but
it is furnished by smaller streams, and is also less abundant
in some textures than in others; for example, though blood
vessels susceptible  of conveying red blood do ramify
through tendons and  ligaments, yet they are not numerous
apparently, not more so, indeed, than what is sufficient to
keep up by a deposite of serum, the flexibility of those parts.
The vascularity of a part during life may be ascertained by
a simple process after death, the most vascular always lose
proportionately of their bulk by drying,  for example,  a 
152
CIRCULATORY SYSTEM.
muscle  shrinks more than a tendon, a gland more than a
muscle.
  Besides the operation of the lymphatics, much of the super-
abundant moisture  is carried off by insensible perspiration
and  evaporation from the surface of the body; the latter
process, however,  is much restrained by the peculiar cha-
racter of the cuticle, without which  it would become ex-
cessive, probably so much so as to exceed any supply of
fluid through the stomach.

  The red globules of the blood,  besides their less obvious
uses, unquestionably serve to inspissate the serous or watery
part, by an intimate mixture with it, and thereby put a cer-
tain  restraint upon its extravasation. They also, from their
size, serve to keep  open the  channels through which the
blood circulates.   So much associated is the existence of
red globules with regular blood vessels, that there are but
few examples of animals having the former, without also
having  the latter; whereas, in animals whose circulating
fluid has not red  globules, but is a mere  serum, the entire
destitution  of regular blood vessels is very common, and
their circulation, if the  name be deserved, consists simply
in the transmission of moisture from one pore to another,
as occurs in a rag or in a sponge,  by mere  capillary attrac-
tion.   Such  animals form a numerous class in the chain of
organized beings, and have a gelatinous consistence.

  A remarkable feature in the vascular system, both arteries
and veins, is the disposition of trunks to run into one another;
or, in other words, to form an anastomosis, whereby if the
blood should be cut off by one rout, it may still be supplied
throughanother.  These communications are frequent in the
head, in the neck, in the thorax, in the abdomen, and in the
extremities;  they exist, indeed wherever the blood vessels
do, and become more numerous  as the blood vessels are
smaller, or more removed from the centre of the circulation.
It is unnecessary  here to specify instances, as the more re-
markable ones will be mentioned at a proper time. But some 
GENERAL CONSIDERATIONS.
153
estimate may be made of their importance, and of the facility
of communication established by them, when it is remem-
bered that cases have  occurred of obstructed aorta without
the circulation ceasing  in  the parts of the body beyond it;
the same has occurred to the venae cavae, and to the thoracic
duct also. *

  The extreme vascular ramifications are called Capillaries,
(Vasa Capillaria,) and they form the connexion between the
arteries  and veins; or,  by  being intermediate to the two,
they are the  ultimate  terminations of the arteries, and the
commencing roots of the veins.  From the extreme tenuity
of these vessels, it is impossible to indicate where the arteries
terminate and the veins begin; yet the continuity of the two
has been repeatedly demonstrated, by throwing injections
from the one  into  the  other system, and by microscopical
observations made on the transparent parts of living animals,
as the mesentery and web foot of frogs, and the tail of fishes.
These facts are sufficiently substantiated by the observations
of Malpighi, Lewenhoeck, Prochaska, and a crowd of others;
yet there are anatomists who hold  a contrary doctrine, and
admit the parenchyma of the ancients (an indefinable some-
thing,  conceived however to be spongy) as a point of ter-
mination for  the  arteries,  and of commencement for the
veins.
  Though the capillaries are all too fine to be seen distinctly
without  a  microscope,  yet  they are found  to have several
gradations  of size.  The largest of them,  or those which
only escape the naked eye, experience successive divisions,
whereby their diameters are reduced from admitting a file of
several globules of blood to the calibre of one globule only, t
The  capillaries  have also frequent anastomoses with  one
another.  Sometimes the artery is simply doubled on itself,
and immediately becomes a vein: on other occasions, several
capillary arteries run into the same vein.  When these com-
munications are unduly enlarged, they constitute what has
been called by Mr. John Bell the aneurism from anastomosis;

       "  Beclard, Anat. Gen.          f Beclard, loc. cit.
  Vol. II.— 20 
154
CIRCULATOR!' SYSTEM.
a frequent mark in young children, and which, when it has
developed itself fully, has a spongy structure resembling the
erectile tissues, as the  corpus cavernosum penis, &c.  As
there is a double circulation, so there is a double capillary
system, one for the lungs and the other for the body gene-
rally;  to these may be  added  a third, which exists in the
liver, between the hepatic extremities of the vena portarum
and the hepatic veins.
  The texture of the capillary vessels is  too  fine to admit
of much scrutiny, but they appear  as simple cylindrical ex-
cavations in the substance of the part to which they belong.
It is not improbable, that they may be uninterrupted conti-
nuations of the internal  coat of the arteries into that of the
veins.  They have striking powers of extension and of con-
traction, and are easily irritated.  An  emotion of the mind,
as a sentiment of shame or a feeling of resentment, quickly
causes those of the face to become turgid with blood.   Lo-
cal stimuli cause congestions in them.  Cold, the application
of a weak acid, or fear, causes them to contract.  Though,
under the influence of the heart, they are less so than larger
vessels. Their innumerable channels cause a comparatively
languid circulation of the blood in them,  for reasons men-
tioned; and by furnishing it with more places of  contact
with their parietes,  put it  more  under nervous influence
than it is elsewhere.
  These vessels are not equally abundant in all the textures
of the body.  Their quantity may be ascertained by the red-
ness which a part acquires by inflammation,  as well as by
fine injections: the latter proof is preferable, as, in the for-
mer, it is difficult to distinguish them from the extravasa-
tions which also occur  at the same time.   The celebrated
injections of  Ruysch, from  their  unusual minuteness, in-
duced  him to think that every solid portion of the body
was vascular, yet he admitted that  some portions were more
vascular than  others, thereby conceding to his antagonists,
that some points at least were not  formed  by blood vessels.
In  the microscopical examinations on living animals, for
example the frog, it is  seen that  in their feet the smallest
capillaries are separated by distinct intervals, while in the 
GENERAL CONSIDERATIONS.            155
 mucous  membrane of the lungs the  finest  needle cannot
 have its point inserted without opening several of them. *
 The younger an animal is the more vascular are its parts:
 but on the contrary, as it advances in age, the proportion of
 parts not susceptible  of injection increases, while the ca-
 pillaries diminish in number.   In cold blooded animals it
 is very evident,  that  some of these  capillaries or arterio-
 venous communications are  large enough to admit a file of
 several red globules abreast, while others allow a single file
 only.   As  a  general  rule, their diameter may be stated at
 from one to five  globules of red blood, t

   The nutrition  of the body depends upon an alternation of
 exhalation and of absorption; but it is still undetermined,
 whether there be any vessels whatever whose especial office
 is that of exhalation, and which  produce the several secre-
 tions and exhalations.  If there be such, they are generally
 designated  by the  term exhalents, and their diameters are
 too small to transmit the red globules of blood; their func-
 tion is consequently to give passage to the serous particles
 only.  This subject has been much agitated by anatomists,
 and marshals  the best authorities on both sides.   Among
 the  distinguished advocates  in  the  affirmative, are Boer-
 haave, Haller, and Bichat; and opposed to  them are Pro-
 chaska, Mascagni, and Richerand. The leading facts of the
 former are: The microscopical observations of Lewenhoeck,
 who speaks of vessels admitting only serous globules;  the
 phenomena of inflammation, which render  red,  parts  na-
 turally white and transparent; the difficulty  of conceiving
 how the nourishment  of certain parts can be maintained,
 whose capillary system of red blood is so limited, in pro-
portion to points  not susceptible of it.  The opinion of Mas-
cagni and others  to the contrary is: That those exhalents, if
they existed, should be seen readily, inasmuch as they are
within the range of a microscope, whose powers enable one
to examine a body much smaller than a red globule of
blood; that injections should penetrate them, instead of being
limited to vessels whose existence is sufficiently confirmed

       •'  Beclard, Anat. Gen.           f  Beclard,  lo.c. cit. 
lot)
CIRCULATOKY SYSTEM.
by examination in the living state; that if during inflamma-
tion they do seem to be injected with red blood, the ap-
pearance is delusive, and depends upon the existing capil-
laries being dilated so  as  to receive more red blood than
usual, upon the formation of new vessels, and upon sangui-
neous infiltration; and, as  to membranes naturally white,
as the conjunctiva, the colour depends upon the capillaries,
while in a healthy state, being so  small that they do not
admit the red globules in a file sufficiently numerous to be
perceived by  the eye,  the globules being probably  then
conducted in a series of one only, or in a single file, like a
string of beads.  It is, therefore, much  more reasonable not
to admit the existence of vessels which it is very doubtful
whether any one  has seen.
   When a watery injection is  pushed  into a blood vessel,
it in a little time  shows itself as a fine dew upon the surface
of the serous and  mucous membranes; in the cellular mem-
brane, and elsewhere.  According to many anatomists, it has
gone through the  system of exhalents,  and  indeed presents
itself to sight in very much the same way,  that exhalation
occurs in the living state.  From the view which has just
been taken, it becomes more probable, that this perspiration
is executed through the interstices or pores of the vessels.
In the dead state  it is merely a mechanical  result, a simple
straining of the fluid; whereas, in the living  body it is a vital
function, continually modified by the peculiar vital  powers
of the organ or membrane where  it occurs;  and, therefore,
presents itself under  the form of the  different secretions.
The question of the exhalents being a distinct set of vessels,
does not, however, appear to be one of much consequence;
because, if they do exist, they must be  very short and very
small; and the assumption of their existence does not throw
any light upon the function of secretion.  For the latter is
still  an  incomprehensible vital process,  and as far as we
have any idea about it, it is quite as easy to conceive of its
being performed in the parietes of the capillaries, as in the
mouths of a distinct set of vessels, whose length is too short
to admit of an estimate.
   Besides the supposed existence of a general system of ex- 
               GENERAL CONSIDERATIONS.            157

halent vessels, some anatomists have thought that there was
a species of them acting  particularly as nutritive vessels.
According to Boerhaave  every part must, therefore, be
vascular. Mascagni thought that the extreme arterial rami-
fications are not only furnished with exhaling, but also with
nutritive porosities,  and that there are every where orifices
of absorbing  vessels,  to  contain the nutritive molecules.
The theories of Bichat and of Prochaska, do not differ ma-
terially from the latter. Whatever may be the mode of ex-
istence, and  the rout of nutriment  to the several parts of
the  body, the operations involved are  entirely too subtle
even for microscopic observation. We, therefore, can only
understand in a general way, that the blood vessels deposite,
and the lymphatics absorb, by invisible avenues in the cel-
lular substance, the molecules of composition and of decom-
position in our organs.*  It is to this power that the name
of vital force has been given, and especially that of the force
of formation (nisus formativus.)
                     CHAPTER II.

          OF THE TEXTURE OF THE ARTERIES.

  The  arteries, though commonly said to be cylindrical
canals, are not exactly so, but as they recede from the heart
increase somewhat in diameter, even  where they do  not
send off any branches.  In this way the arteries of the um-
bilical chord are evidently larger as they get  nearer  the
placenta;  and  the spermatic arteries of a  bull as they get
nearer to the testicle. Observations made on the carotid ar-
teries of the camel and of the swan by Mr. Hunter,t tend to
prove the same disposition in them.   It is probable that the
rule extends to all arteries throughout the system, but it
cannot be ascertained with  so  much certainty,  because of
the close succession of branches which  they send off.

     * Beclard, loc. cit.      f On the Blood and Inflammation. 
158
CIRCULATORY SYSTEM.
   Arteries have within themselves a power of increase con-
 nected with  the  exigencies of the part to which they go;
 thus  the uterine  arteries increase much in  their capacity
 during pregnancy, while the hypogastric, from which they
 are derived,  augment  inconsiderably,  and  the primitive
 iliacs not in an appreciable manner.   In animals of the deer
 kind, whose horns are  deciduous, the same  augmentation
 of arterial trunks occurs while the horn is growing.  Tu-
 mours are supplied in the same way.   But in all these cases
 after  the exigency is passed  the vessels diminish to their
 primitive size.
   With  the exception of the semilunar valves at the orifice
 of the pulmonary artery and of the aorta, there are no others
 in the whole  arterial  system.   These valves  permit  the
 blood to pass in  the  direction of the  circulation, but  not
 backwards, as they are closed immediately upon the cessa-
 tion of the  contraction  of the ventricles.  The tricusped
 valve, and the semilunar of the pulmonary artery, are na-
 turally not so perfect in  their closure as those on the other
 side of the heart, but permit  a small  quantity of blood to
 retrograde, t   As life advances the valves of the aorta are
 much  disposed to ossifications and derangements of diffe-
 rent kinds; which render them much less perfect, than those
 of the pulmonary artery.

   The arteries are composed of three coats;  an external, a
 middle, and an internal.
   The External Coat, also  called  cellular or nervous, is in
fact, condensed cellular  substance formed into a cylinder.
Its fibres run in every direction so as to be perfectly inter-
woven with one another.  The exterior periphery of this
coat is continued into  the adjacent cellular substance, but its
internal face is united more closely to the middle coat,  not
however so tightly as to prevent a slight sliding of the one
upon  the other, and  to  forbid their  easy separation by a
knife.  Scarpa is not  disposed to admit this as one of  the
 coats of arteries, and  says that it  only serves as an exterior
* Hunter, lot. cit. 
              TEXTURE OF THE ARTERIES.            159

envelope, and retains them in their places.   This coat ma-
nifests its fibrous character in not being disposed to secrete
fat, and is more distinct in the large arterial trunks.   It has
considerable strength and elasticity, both  circularly and
longitudinally, and is remarkable for its whiteness.  If an
artery be surrounded by a tightly drawn ligature, the mid-
dle and the internal coats will  be completely cut through
by it, while the external coat  remains entire.   This coat
answers then  the purpose of a  strong investing fascia,* in
which respect it may be  considered as a sheath to the pro-
per arterial structure, though the term sheath is commonly
applied to the cellular membrane on its outer side.

   The Middle Coat of the arteries is called the Muscular,
the Proper, the Tendinous, and so on.   It is of a light yel-
lowish tinge,  and  decreases  continually in  thickness, with
but few exceptions, from the heart to the ends of the arte-
ries;  it is, however, proportionately thicker in the small
arteries than in  the large  ones.   Its fibres are  circular, but
do not individually perform the circuit of the vessel.   They
are parallel to each other, and adhere laterally by very slen-
der ties.   In  the larger arteries  this coat may be divided
into several laminae, though the  division is entirely artifi-
cial.   There  are no  longitudinal fibres whatever in it, the
consequence of  which is, that an artery divested of its ex-
ternal coat, yields more readily  in the direction of its length
than of its circumference.
   The middle coat has a  firmness, whereby, even when an
artery is emptied, the cylindrical shape is still retained.  Its
character seems to be the result of a mixture of elastic and
of muscular properties derived from a state of tissue entire-
ly peculiar; but which some anatomists have been very de-
sirous of ranging under the head of muscles, others under
that of ligaments, and a third, under both united.   The ce-
lebrated Jno.  Hunter, whose observations  were  generally
made with the most scrupulous  attention to  perfect exacti-
tude,  were often repeated so as to make one confirm ano-
* Jones on Hemorrhage. 
160
CIRCULATORY SYSTEM.
 ther; and who has  received that sanction of  greatness in
 which one's posthumous reputation becomes more exalted
 than the living; bestowed much attention on  this subject.
 He  was induced to believe that this middle coat was formed
 by a muscular lamina internally, and an elastic one exter-
 nally; which distinction might be rendered evident by cut-
 ting a  contracted artery through  transversely, when the
 muscular coat would be found  projecting beyond the other.
 He  acknowledges, however, that he never could discover
 the  direction of the  muscular fibres: though  he supposed
 them to be oblique,  because their degree of contraction was
 greater than a straight muscle could produce.
   The elastic contraction of an artery, is manifested both
 in the direction of its length and of its circumference;  for,
 when put upon the stretch in either way, it has the ability
 of returning  to its original dimensions after the distending
 force ceases.   The  Muscular  contraction, however, only
 occurs in  the circumference, and not at  all in the length;
 by it the calibre of arteries is reduced to a very small dia-
 meter, if  an  animal  be slowly bled to  death.   If, in this
 contracted condition, an artery be slit open longitudinal-
 ly, the elastic coat will, at the cut  margin, project beyond
 the other, which Mr. Hunter  considers  as another way of
 ascertaining  the existence of the two tunics.   But if this
 same artery  be then stretched transversely, the muscular
 coat will project beyond the other, for the reason, that if a
 muscle, after death,  be elongated by force, it has no power
 of returning from that state, but will  remain precisely as it
 is: whereas,  elasticity being a  property of matter enjoyed
 quite as fully in the  dead as in the  living state, the elastic
 coat of the artery returns to the medium condition.
  Mr. Hunter, with  the view of satisfying himself on these
 several points, had a horse bled to death, so as to obtain the
vessels at  their minimum of contraction.  A circular sec-
tion  of the aorta measured, at  first, five inches and a half,
 and, on being stretched, it lengthened to ten  inches and a
 half; being let alone, it contracted to six inches, at which
 it remained  stationary; the difference between six  inches 
TEXTURE OF THE ARTERIES.           161
and ten and a half was then the amount of its elastic power,
w'ile only half an inch of contraction was due to the mus-
cular stratum, or, in  other words,  an eleventh of  the
whole.
  A section of the iliac  artery, measuring two inches in
circumference, on being  allowed to contract after stretch-
ing, measured two and one-third inches; it, therefore, gained
one-sixth the amount of its muscular contraction.  A sec-
tion of  the axillary artery gained one-eighth—of the caro-
tid, two-thirds—of the radial artery, doubled its primitive
extent.   From all which the inference was  drawn, that the
power of recovery in a vessel is  greater,  in proportion as it
is nearer the  heart, but  lessens  as the distance increases,
which  shows the decrease of elastic,  and  the  increase of
muscular power.
  The  elastic coat gives a middle state to an artery, or has
a continued tendency to it; if, therefore, the artery be too
much dilated, it contracts it, and if it be too much contract-
ed, it dilates it, all of which is readily exemplified by a cy-
linder of gum elastic, which, whether compressed or dilated,
has only one state of repose, to  which it immediately re-
turns on being left to itself.   Mr.  Hunter supposed,  that a
certain  degree of elasticity is continued to  the very end of
every artery, from this quality being  better suited to sus-
tain a permanent resistance than  muscular power; as a pipe
of lead, from its want of elasticity, finally  becomes stretched
and useless under the pressure of a column of water, where-
as, one  of iron, from being elastic, always reacts efficiently.
It is this elasticity in the arteries, which causes the blood,
at a little distance from the heart, to  flow through them in
a continued jetting stream when  they are opened, although
it is supplied to the aorta  by interrupted strokes.  In this
way, as the artery is more distant from the heart, the stream
becomes proportionately regular.
  " The muscular power of an artery renders a smaller
force of the heart sufficient for the  purposes of circulation;
for the heart need only act with  such force as to carry the
blood through the larger  arteries,  and then the muscular
  Vol. II.—21 
162
CIRCULATORY SYSTEM.
power of the arteries takes it up, and as it were, removes
the load of blood while the heart is dilating.  In confirma-
tion of this remark, it is observable in animals whose arte-
ries are very muscular, that the heart is proportionably
weaker, so that the muscular power of the vessels becomes
a second part to the  heart, acting where the power of  the
heart begins to fail,  and increasing  in  strength as that de-
creases in power."*

   The  Internal Coat of the arteries is  designated by  the
terms  Nervous and  Arachnoid.  It is continued from  the
ventricles of the heart, in the left one of which it is of un-
usual thickness.   It  is the duplication  of  this membrane
with some fibres interposed,  that composes the semilunar
valves of the aorta and of the pulmonary artery.   Its in-
ternal face is smooth, polished,  and  moistened with a kind
of humidity which permits the blood to  flow through with
diminished friction.   In the larger arterial trunks,  some
small longitudinal wrinkles are observable in it; and  when
an artery has been cut through, as in amputation, it is dis-
posed to retract in small transverse wrinkles.   It is, there-
fore, not very extensible, but has, according to the experi-
ments  of Sir Everard  Home,t a considerable degree  of
solidity and strength.
   Ossifications of this  membrane are very frequent after
the age of sixty.

  In addition to the tunics mentioned, cellular  substance,
vessels, and nerves enter into the structure of arteries.
  The Cellular Substance is not abundant, and serves prin-
cipally to unite the sides of the circular fibres to one ano-
ther, and to join the internal to the middle coat.
  The Vessels (Vasa Arteriarum)  consist both in arteries
and in veins, and come from the adjacent trunks, instead of
from those  on which they ramify.   They may be  made
very distinct by a fine injection, or by laying them bare in

  * Hunter, loc. cit.
  •f Transactions for the Improvement of Medical and Surgical Knowledge,
vol. i. 
TEXTURE OP THE ARTERIES.
16.3
the living body; when in a little time after exposure, they
begin evidently to carry red blood, and to grow turgid as
in inflammation.  The difference in the colour of the blood
distinguishes these  arteries  from the  same kind of veins.
Both arteries and veins  may be  traced very well into the
middle coat, but not upon the internal, though the changes
which occur in the latter, from disease and upon the appli-
cation of ligatures,  prove clearly that exhalation and ab-
sorption is continually going on there.  For in inflamed ar-
teries, an exhalation is seen upon their internal surface, and
when a coagulum has been produced by ligature, it is final-
ly absorbed.
   The  Nerves of the arteries,  according to Wrisberg and
Beclard, are numerous and considerable, form around them
a plexus resembling that of the par vagum around the oeso-
phagus,  and follow them into the interior of our  organs,
with the exception of the brain; which has them only to its
surface.   They are  proportionately more abundant in the
aortic than in the pulmonary system; also upon the smaller
than upon the larger arteries.   The arteries of the head, of
the neck, of the thorax, and of the abdomen, are supplied
from the sympathetic nerve, while those of the extremities
are supplied from the nerves of the spinal marrow.
   The  passing of  the  blood through the arteries is accom-
panied with a pulsating motion, which for  the most part, is
exactly synchronous with the contraction  of the left ven-
tricle, and  depends upon an increased quantity of blood
thrown into  them  at the moment.   The  dilatation of the
artery may be both  seen and  felt; "but were we to judge
of the real increase of the artery by this, we should deceive
ourselves; for when covered by integuments, the apparent
effect is much greater than it really is in the artery itself;
for in laying such an artery bare, the nearer we  come to it,
the less visible is its pulsation; and when laid entirely bare,
its motion is hardly either to  be seen or felt.    This appa-
rent diastole of the artery is augmented in proportion to the
solid matter covering it,  whence tumours over  large arte-
ries have considerable motion given to them, and  have often 
164
CIRCULATORY SYSTEM.
been supposed to be aneurismal.   Arteries, in fact, during
their diastole or dilatation, increase much more in length
than in width, and are thrown into a serpentine course; in-
stead, therefore, of the term  diastole,  it should rather  be
called  the elongated state."*  Mr.  Parry,  of Bath,t has
denied that the arteries dilate  at all during their diastole; his
opinion,  however, is peculiar,  though, in an  experiment
performed some years ago upon the carotid artery of a calf,
its correctness appeared to me then to be fully proved.
  There is no part of the human body which presents more
frequent varieties, in different individuals, than the arteries.
These  varieties are found, in  their place and manner of ori-
gin, in position, and  in the number of their ramifications.
They are comparatively rare  in the  trunks of the first or-
der, more common in those of the second, and still more
usual in those of the third and fourth.  From these causes,
discrepancies are  continually found  in the descriptions of
the most approved authorities, and must last so long as wri-
ters repose upon a partial  experience, instead of referring to
what has been most generally observed.
                   CHAPTER III.

            OF THE TEXTURE OF THE VEINS.

  The veins,  from their duty of receiving the blood in all
parts of the body from the extreme arteries, and returning
it to the  heart, by successively collecting  it into the two
venae  cavae, may be more appropriately compared  to the
roots of a tree, than  to  its branches.  The variations  in
them, as well  as their anastomoses, are more frequent than
in the arteries.
  They are more numerous than the arteries; for, in addi-
tion to two venous  trunks attending each artery wherever

  * J. Hunter, loc. cit.
  f Experimental Inquiry on the Pulse, 181(5—1819. 
TEXTURE OF THE VEINS.
165
the structure of the  part is intended for locomotion, as in
the extremities, and in some places upon the trunk of the
body, there is a very abundant class of veins which are
superficial or  subcutaneous, and which, when  filled pro-
perly with injecting matter, form a fine vascular  network
over  the  whole  surface of the  body.*  These superficial
veins, in some places, form trunks even larger than such as
attend the arteries, and especially in the extremities.   Be-
sides the excess in number, the veins which attend the ar-
teries (Venae Comites) have a capaciousness which, in many
cases, is double that of the latter.  From these several cir-
cumstances, it results that the area of the venous system
vastly exceeds that of the arterial.
   In some cases  the veins follow precisely the course  of
the arteries, one for one,  as  in the greater number of the
viscera of the abdomen, where they have common points
of entering and departure.   Sometimes two arteries dis-
charge into one vein, as in the penis, the clitoris, and the
umbilical chord; sometimes they pursue a course entirely
different from the arteries,  as  in the pia  mater.   For the
most part they are less tortuous than the arteries.
   The veins, when  injected,  assume a cylindrical shape,
yet they differ materially from  the arteries, in having much
thinner coats, and in being so pliable  that they collapse by
their own weight.  In the lower extremities, however, near
the feet and upon them, as the veins sustain the pressure of
a long column of blood; they have additional thickness and
strength,  so as to approximate  them  more to the arterial
structure.   This provision will be found occurring in most
places where  they have much duty to perform.
   " They are similar to the arteries in their structure, be-
ing  composed of an elastic  and  muscular substance;  the
elasticity preserves them in some degree in a middle state,
although  not so  perfectly as it does in the  arteries.   The
muscular  power  adapts  the  veins to the  various  circum-
stances, which require the area  to be within the middle
state, and assists the blood in its motion towards the heart."t

    Pauli Mascagni Anatom. Univers. Pisis, 1823.   f Hunter, loc. cit. 
166
CIRCULATORY SYSTEM.
   The External Coat is thinner and not so strong as that of
the arteries; in other respects, the resemblance is sufficiently
close not to require any particular comment.

   The Middle Coat, near the  entrance of the larger veins
into the  heart, is distinctly muscular.*  It is formed of soft
extensible fibres, many of which, when the vein is held up
to the light, appear longitudinal, while the most internal are
circular; there are difficulties, however, in the separation of
these fibres, which prevent  their course from being accu-
rately ascertained. Bichat and Meckel assert, that the whole
of them are longitudinal, and that  there are none circular.
   This coat, in  the  human subject, is much thicker in the
system of the ascending than of the descending cava; it is
also thicker in the superficial than in the deep-seated veins.
In some  subjects it is much better developed than in others.
In certain parts  of the body it is entirely deficient, as in the
sinuses of the dura mater, and has its place supplied by this
membrane;  the same deficiency exists  in the sinuses of the
bones.

   The Internal Coat  is more delicate and extensible than
the corresponding one of the arteries,  is less liable to rup-
ture,  and less disposed to ossification.   It is thrown into a
considerable number of duplications, forming valves.  Each
valve is of a semicircular shape; is connected by its convex
edge to the vein, while the straight edge is loose, and turned
towards the heart. When the veins are injected backwards,
these valves  may be  forced in  the larger trunks, and give
them a knotted  appearance.  The valves are commonly  in
pairs, but in certain veins, as the crural and the iliac, there
are three of them together;  very rarely do they amount to
four.   In some  instances there is but a single one; this ar-
rangement  is more frequent at venous orifices,  as the great
coronary vein of the  heart, the vena  cava  ascendens, the
vena  azygos.  They are  frequently found reticulated as if
they had been lacerated,  whence it has been supposed that
* Beclard, loc. cit. 
TEXTURE OF THE VEINS.            167
the fibres which cross the sinuses of the dura mater are an
elementary approach to them.
   The valves are more  abundant in the superficial than in
the deep-seated veins, but they do not exist every where.
There are none in the branches of the vena portarum, ex-
cepting the vasa brevia;  none in the brain, in the spinal
marrow, in the umbilical vein, the  cervical veins, the kid-
neys, womb, ascending and descending cava, or in the me-
dian vein. The valves are proportionately more abundant in
the lower extremities.

   From the tenuity of the parietes of the veins, the blood
may  be readily distinguished  circulating through  them.
Their coats, like those of the arteries, are vascular, or have
the vasa vasorum.  The arteries come from the nearest small
trunks, while the corresponding veins do not empty  imme-
diately, but secondarily, into the trunk, whose parietes they
supply.

   Their  elasticity,  both transversely  and longitudinally,
is well marked; but they are not so extensible  in the latter
direction as the arteries, while they are more so transversely.
There can be no donbt of their spontaneous powers of con-
traction, for it is abundantly proved by their  diminishing
much in  volume upon the  application  of cold; moreover,
when a venous trunk, distended with blood, is intercepted
by two ligatures and then punctured, it empties itself en-
tirely and rapidly.
   The circulation in  the  veins  is produced, in a principal
degree, by the contraction of the heart; their own contrac-
tion may  also favour  this  motion, as well as lateral pressure
from  contiguous parts, as the movement of the blood in the
smaller arteries is so continued as to be almost without pul-
sation, so the latter disappears entirely in the veins. It is not
clear that this circumstance depends exclusively on the fric-
tion experienced by the blood in passing through the capil-
laries, but is probably rather owing, as  Mr. Hunter  has
suggested, to the veins receiving their blood from different 
168
CIRCULATORY SYSTEM.
arteries, some of whose  channels are more circuitous than
others and consequently their blood  arrives  at different
times.  The momentum of the heart then, even if it did im-
pinge upon those channels, would not be synchronous upon
the venous trunk, but would be divided in such a way as to
produce a  tremour or confused motion.  The*Iarger veins,
however, have near the heart a pulsation during the contrac-
tion of the auricles, arising from the arrest of their circula-
tion at the moment.   During inspiration, the vacuum created
in the thorax hurries on the blood to the heart, but in expi-
ration it is somewhat impeded. *

   It has sometimes  happened, that a large  vein near the
heart being opened by an accident or an operation a strong
inspiration has caused the introduction  of air, which, being
carried to the heart, has produced instant death.   It lately
occurred in Paris, to the  celebrated surgeon Dupuytren.
                     CHAPTER IV.


                      OF THE BLOOD.

   The Blood, in the human subject, and in many animals,
is of a red colour.  It is about the consistence of thin size,
has  a  peculiar smell, a nauseous and slightly saline taste,
and  is  somewhat heavier than  water, its  specific  gravity
being  about 105.  Its quantity is  variously estimated  at

  * This ancient observation has lately been renewed, with additional inte-
rest and details, by M. Barry of Paris.  See a report of MM. Cuvier and
Dumeril, concerning the Influence of the Atmosphere on the Circulation of
the Blood, in the Philadelphia Journal of the Medical and Physical Sciences,
July,  1826. M. Barry has probably assigned too much importance to this
influence, as it is certain that the circulation may go on very well where no
vacuum is produced at intervals in the thorax; for example,  in the foetus,
in incubation, and in fish. 
THE blood.
169
from eight to one hundred pounds, so that there would seem
to be no very exact means of ascertaining this point.
   So  long as  it continues to circulate, or while it is still
flowing from an opened vessel, it has, to common inspection,
the appearance of a homogeneous fluid; yet, after it has been
drawn a few minutes, and permitted to remain at Test, it as-
sumes a thick gelatinous condition, expressed by the term
coagulation, and by  which it ceases to be any longer fluid.
This change has scarcely taken place, when a  spontaneous
separation follows whereby it is resolved into a watery part
called  Serum, and into a thick condensed mass called Cruor
or Crassamentum.  The serum first shows itself on the sur-
face of the coagulum, in small drops, which quickly increas-
ing in number and size, finally run together, and form a mass
of fluid exceeding considerably that of the crassamentirm.
The coagulation begins on the surface of the mass, and by a
thin pellicle, which shows itself in  three or four minutes;
commonly at the end of twenty minutes  the coagulation is
complete throughout, but this rule varies according to the
state of the body at the moment; and the coagulation is more
protracted when the quantity of blood is large and has been
drawn through a large orifice, than  where it is small, and
has been evacuated through a small orifice.   The separation
into serum and crassamentum, though sufficiently evident
after a few hours,  yet requires  some days for its complete
accomplishment; for the coagulum still continuing to con-
tract, expels more and more of the serum.
   The peculiar complexion of the blood depends upon a red
colouring matter consisting in globules.   This matter does
not seem to be an indispensable constituent, as many ani-
mals are entirely deprived of it, and such as naturally are
possessed of it, may have its quantity very much reduced
by repeated bleedings.  The colouring matter is generally
an ingredient of the crassamentum, so that the whole of the
latter has a red appearance;  yet there are some conditions
of the body in which a spontaneous separation of it takes
place, more or less completely.   For example, in inflam-
matory diseases the blood does  not coagulate so soon as in
   Vol. II.—22 
170
CIRCULATORY SYSTEM.
health;  and the red globules, from  being naturally heavier
than the other constituents of the crassamentum, subside to
its bottom and  leave it of a white semitransparent colour.
It is this white part upon which depends the whole proper-
ty of coagulating, and which has been  called coagulating
lymph.    We have therefore three constituents of blood
manifested by its own  spontaneous changes; the serum, the
red globules, and the coagulating lymph.
  Coagulation, contrary to popular opinion, is not assisted by
cold, but rather retarded by it; heat assists it.*  If the heat
be raised to 120°, blood will coagulate five  minutes sooner
than if left at its natural standard, and even sooner than if its
temperature be reduced to 50°.  If blood be frozen quick-
ly, before it has time to coagulate,  on being thawed  it re-
turns to the fluid state, and will coagulate afterwards.  The
contact  of air does not  produce coagulation.   Dr. Physick,
in order to ascertain this point conclusively,  took a glass
tube, which had a stop cock at each end, and  attached one
of its ends to the vein of a dog.  A  current of blood was
then conducted through the tube, and while it was flowing,
the far stop cock was  closed, and immediately afterwards
the other; thus a column of blood was obtained which had
not touched the air.  After permitting it to remain a pro-
per  time,  the  tube was broken  asunder, and the  blood
found coagulated as usual.   Rest is not indispensable to the
process; for blood, if shaken in a vial, will still coagulate.
The division of the blood into small masses expedites coa-
gulation.   Therefore,  when it  flows slowly from the ves-
sels, falls from some height, or runs for a distance over the
surface of a dish, it coagulates sooner than  under opposite
circumstances.   The latter are then auxiliary to the blood
manifesting the sizy coat, one of the concomitants of inflam-
mation; because, if the  coagulation be very rapid, it will pre-
vent the constituents of  the crassamentum from separating
from one another, by entangling the red globules in the coa-
gulating lymph.
   After death the blood is coagulated in the veins, though
* Hunter on the Blood.  Hewson. 
                 SERUM OF THE BLOOD.             171

not so perfectly or generally as  is supposed, for there are
no subjects which do not bleed from the large veins, when
the latter are opened.
  There are many modes of death which prevent entirely
the coagulation of the blood in  the vessels, for example,
where life is destroyed by a paroxysm of excessive anger;
by electricity;  by lightning; by a blow upon the stomach;
by certain fevers of a typhoid character.   Many chemical
articles prevent its coagulation on being mixed with it.

         SECT. I.--OF THE SERUM OF THE BLOOD.

  Serum is common to the blood of all animals, and is con-
sidered, by Mr. Hunter, to  be  more abundant in such as
have  red globules.  It is generally of a lighter specific gra-
vity than the crassamentum.  I have, however, often seen
the latter floating in  it, which shows the contrary in some
instances.  Though its separation commonly depends upon
the coagulation of the latter, yet that process is not indis-
pensably necessary, as was once  witnessed, by Mr.  Hunter,
in a lady, in whom the serum was disengaged from the coa-
gulating lymph, while the latter was  yet  in  a fluid state.
The phenomena of dropsy also prove the same point.
  Serum, though very limpid, is not so much so as water.
It is  a light yellow or straw colour, varying somewhat in
different subjects.  It contains a large quantity of albumen,
or matter resembling the white of an egg.   It also consists
of water, of soda uncombined, and of some of the salts of
soda,  the presence of all which may be manifested in seve-
ral  ways.  For example, when  exposed to a heat of 140
degrees  of Fahrenheit,  it becomes opaque, and at 160 or
165 coagulates firmly.  During  this process a great deal of
air is  disengaged from it.  It is also coagulated by spirits
of wine, by all the mineral acids, by corrosive sublimate,
and by many  other articles.  Mr.  Brande  considers  it  as
an albuminate  of soda, with an excess of its base, and that
its fluidity depends  on the quantity of  soda; when, there-
fore, the latter is removed  or neutralized  by an acid, the
albumen coagulates.    Under the action of the galvanic pile, 
172
CIRCULATORY SYSTEM.
like  the  influence of heat, the soda produces  mucus, by
blending with a part of the albumen: and the remainder of
the latter, not being able to retain its fluidity after the ab-
duction of the soda, coagulates.
  This mucus is probably the part which Mr. Hunter speaks
of as retaining its fluidity when other portions of the serum
are coagulated by heat.  It is observed in meat either roasted
or boiled, and comes from it as a thin, limpid fluid, some-
what tinged with the red globules.   The older the animal
is, the greater is  its comparative quantity;  in lamb there is
scarcely  any of it, whereas, in mutton five or six years old,
it is abundant; the  same rule seems to hold in regard to the
human subject.   This serosity or  mucus is coagulable by
Goulard's Extract. *
   The serum is not always  transparent,  but  sometimes
wheyish and thin; when it  settles, it often throws  up  a
white  scum like  cream.  This more frequently occurs in
pregnant women, though  it is not confined exclusively to
either  sex, or to any known condition of body.   The speci-
fic gravity of the globules composing this scum varies; for
though it generally floats on  the  surface of  the serum, it
does not always: it also sometimes swims, and on other oc-
casions sinks in water.  It has been erroneously considered
as chyle not yet assimilated, or as absorbed fat or oil.  It
is, probably, this substance which  also presents itself under
the  form of microscopic globules in the coagulum of serum;
and, when serum has been kept for several  days, is depo-
sited in the form of globules at its bottom.   These globules
present a singular motion of ascent and descent in the se-
rum;  upon the application of heat to it by holding it in the
hand.   It is said that albumen, coagulated, presents a very
 close resemblance to fibrine.t
   The presence of soda uncombined in the serum, is rea-
 dily ascertained  by tincture of litmus or of red  cabbage,
 which are both made green by it.   Sulphur combined with
 ammonia, is also found in it.   Owing to the presence of sul-
 phur,  serum  has the effect of blackening silver when left

           * Hunter, loc. cit.            j Beclard, loc. cit. 
RED GLOBULES OF THE BLOOD.
173
in it, and also has its power of  dissolving the oxydes of
mercury, iron, copper, and other metallic preparations.

 SECT. II.--OF THE  COAGULATING LYMPH OF THE BLOOD.
   Coagulating lymph, or fibrine, when  circumstances are
suitable for collecting it, freed from the red globules, offers
the appearance of a  semitransparent body  of a very light
drab colour;  it is elastic and strong, and when subjected to
the microscope has  the  appearance of muscular fibres, by
being  composed  of  colourless globules.  Like muscle,  it
also, when  macerated in water,  resolves itself  into those
globules before it putrefies.
   If the blood, while flowing from an animal, be collected,
and, at the same moment, stirred round and round with a
rough stick, the fibrine will gather upon  the  latter in a
fibrous form, so as  to  resemble a mass of entangled and
knotted  packthread.  The fibrine may be afterwards washed
almost white, and at any rate, so as to clear it entirely from
the red globules.
   The fibrine, when dried, loses  greatly in its bulk and
weight, by the evaporation of the serum from it, so that the
proportion which it seems to bear to  the  whole mass  of
blood  is much less considerable than one  would suppose
from seeing it in the simple coagulated state.
   "The coagulating lymph of the blood being common,
probably, to all animals, while the red particles are not, we
must suppose it from this alone to be the most essential part;
and, as we find it capable of undergoing, in  certain circum-
stances,  spontaneous changes, which are necessary to the
growth, continuance, and preservation of the animal; while
to the other parts we cannot assign any such uses, we have
still more reason to suppose it the most essential part of the
blood  in every animal."*

     SECT. III.--OF THE RED GLOBULES OF THE BLOOD.

   The particles of blood upon which its red colour depends
 are, by the majority of observers, considered to be globular,
* Hunter, loc. cit. 
174
CIRCULATORY SYSTEM.
and while the blood circulates they float about in the lymph
and  serum.  They are of the  same size  in animals of the
same species, and have no tendency to run into each other,
as globules of mercury would.  They are plastic, by which
they can  assume  an elliptical shape when they circulate
through vessels of a very small size.
   According to the microscopical observations of Mr. Bauer,
each globule is one  two-thousandth part of an inch in dia-
meter, but Capt.  Kater does  not consider it to exceed one
five-thousandth part  of an  inch.*  There seems, however,
to be a great uncertainty in these estimates of form and of
size, inasmuch  as  different observers do  not agree among
themselves.   Father Delia Torre  considered  them as flat
circles or  rings with a perforation in the centre, while Mr.
Hewson, in ascribing the same shape, represented them as
hollow or vesicular,  with a red dot in the middle.   Mr.
Bauer, on the contrary, considers that the dot, or colouring
matter of the globule, is placed upon its periphery. As the
colour  is supposed to depend  upon particles of iron, Dr.
John Mason Good has wittily suggested, that,  according to
Mr.  Hewson, we have the wheels of life moving upon iron
axles, whereas, according to Mr.  Bauer, they only have
iron tiers, t
   It has been observed that the red globules are the heaviest
part of the mass of blood, and are therefore always disposed
to subside to the bottom of the crassamentum, though from
the quick coagulation of the latter, they can seldom do it
before they become entangled in it, and thereby fixed to a
certain place.  They do  not invariably retain their form,
but are readily dissolved  in water.  They are, of course, in-
soluble in serum.   Urine does not dissolve them; neither
does a solution of muriate of soda,  of sal ammoniac, epsom
salts, nitre, diluted sulphuric or muriatic acid, the latter,
however, deprives them of colour.
   The solution of red globules in water is manifested by the
mixture becoming of a fine transparent red, and the process
takes place almost immediately. On the contrary, when the

   * Phil. Trans. 1818.      f Study of Medicine, vol. U. p 25. 
             RED GLOBULES OF THE BLOOD.          175

globules refuse to be dissolved a muddy mixture is formed.
When they are dried in serum, and afterwards soaked again
in it, they do not resume  the globular form.  They have
more substance than the coagulating lymph, for they do not
lose  so much of their bulk by drying.
  Notwithstanding the doubts that have been raised on the
subject, it seems now to be very well ascertained, that iron
is the colouring principle of  the red globules of the blood,
though it cannot be detached in the coloured state, owing to
the absolute necessity of using strong heat, or concentrated
acids to destroy the substance with which it is combined.
The iron is an oxyde with a small quantity of the sub-phos-
phate, but a knowledge of this fact does not enable the che-
mist to imitate red globules by mixing these  chemical sub-
stances with albumen.  The process  by which Berzelius
obtains iron from the blood, consists in placing a clot of the
latter upon  blotting paper, whereby its serum is absorbed.
The clot being afterwards put into water, its colouring mat-
ter is dissolved, while the lymph remains entire; by remov-
ing then the lymph and  evaporating the water, the colour-
ing matter is obtained, which, on being  reduced to  ashes,
renders about one two-hundredth part of its weight in iron.
   The chemists also inform us, that fibrine,  albumen, and
the colouring matter, all resemble  one another so closely,
that they are only modifications of one and  the same sub-
stance; and,  that each  of them yields, upon decomposition,
phosphate and carbonate of lime, though  these ingredients
cannot be detected  by tests applied to the  entire mass of
blood.
   " It is difficult to determine by what means the iron, or
the sulphur, or the elementary principles of calcareous earth,
obtain an  existence in  the blood.   If  these materials were
equally diffused throughout the surface of the earth, we
might easily conceive  that  they were introduced through
the medium of food.  But as this is not the  case; as some
regions, like New South Wales, at least, on  this side the
Blue mountains, contain no limestone whatever, and others,
no iron or sulphur, while all these are  capable of being ob- 
176
CIRCULATORY SYSTEM.
tained apparently as freely from the blood of the inhabitants
of such regions, as from that of  those who live in quarters
where such materials enter largely into the natural products
of the soil; it is, perhaps, most reasonable to conclude that
they are  generated in the laboratory of the animal system
itself, by the all-controlling influence of the living princi-
ple."*

   The red globules, according to the opinion of Mr. Hunter,
from  not being pushed into the extreme arteries, where the
coagulating lymph reaches, and from not being found in* all
animals,  do not  contribute to the growth  and to the repair
of the system.  But they seem to be connected with strength,
in such animals as have  them, as the strength acquired by
exercise increases their proportion and occasions them to be
carried abundantly into  parts which previously, from a de-
bilitated state, received  them but partially, if at all.   This
fact is well known to graziers, who  keep their quantity in
certain animals,  as veal, reduced  by  quietude and  frequent
bleeding.
   Their source is not understood, though many conjectures
on the subject have been hazarded.  Mr. Hunter's opinion
was, that they do not appear to be formed in those parts of
the blood already produced, but rather to rise up in the sur-
rounding parts;  as,  in the  incubated egg they exist in the
form  of a zone composed of dots, previously to the forma-
tion of vessels. This fact ought to quiet all speculations about
their  coming from the spleen, thymus  gland, and  so on.
* Good, loc. cit. 
BOOK  VIII.
                       PART  II.

      Special Anatomy of the Circulatory System.


                     CHAPTER I.

           OF THP, HEART AND PERICARDIUM.

   The Heart, (Cor,) the centre of the circulation, is situated
in the thorax, between the sternum  and the spine; being
bounded on its sides by the lungs, and below by the tendi-
nous centre of the diaphragm.  It is a hollow muscular or-
gan.
   The heart is of a conoidal shape, but flattened on the sur-
face, which lies upon the diaphragm.  This flat surface is on
a horizontal line with the lower end of the second bone of
the sternum; the  base of the cone is towards the vertebrae,
and looks obliquely backwards to the right side, while the
apex is about the junction of the left fifth rib with its carti-
lage. Being placed between the right and the left pleura, in
the mediastinum, it is surrounded by its own proper capsule
called the  pericardium.  Its common weight is about six
ounces.   Its greatest length, to wit, that from  the apex to
the base is about five and a half inches,  four of which are
taken up by the ventricles; its base is about three and a half
inches in diameter.
  The heart is divided into four cavities; two auricles and
two ventricles;  the places where the partitions are placed
between  these cavities are marked on the  surface of the
heart by fissures,  sufficiently distinct to be immediately re-
cognised.  The two auricles form the base of the heart, the
   Vol.  TI.—23 
178
CIRCULATORY SYSTEM-
ventricles constitute its body, and the left ventricle, by be-
ing extended somewhat beyond the right, forms the apex.
The right auricle and  the right ventricle are the two cavi-
ties which are nearest  to the right side of the body, while
the left auricle and the  left ventricle are the two cavities
nearest to the left side.  It will, however, be understood,
from the general  observations already made,  that the rela-
tive situation of these cavities is such that the right ones are
in front of the others, and present obliquely forwards to the
right side, while those on the left side look obliquely back-
wards  to the left  side.  This position of the heart causes it
to encroach more upon the left cavity of the thorax than it
does on the right;  from  which cause its pulsations may be
very easily distinguished where the left ribs join their car-
tilages, while on the  right side of the  sternum there  is
scarcely ever a perceptible pulsation.

   The Right Auricle  (Auricula Dextrq,, anterior) is an
oblong cuboidal cavity.  It is joined at its posterior supe-
rior angle by the  descending vena cava, and at its posterior
inferior angle by the  ascending vena cava.  The structure
of the  auricle, between these two points, seems to be only
a continuation of  that of the veins.  These veins enter with
a direction slightly forwards, so that their columns of blood
are not directly opposed to each other.   In front of this
continuation of the two  veins, the auricle is  dilated into a
pouch  called its  sinus; the upper extremity of the  latter,
just in front of the descending cava, is elongated into a pro-
cess with  indented edges,  that hangs loose and has some
general resemblance to the ear of an animal,  from which it
is probable that the term Auricle has been derived.
   The exterior surface of this cavity is smooth and uniform,
but its internal surface is varied at several places.   About
midway between  the  orifices of the two cavae is found a
transverse prominence, the Tuberculum  Loweri, which is
occasioned by the continuous structure of the veins meeting
at an obtuse angle.  This cavity is separated from the left
auricle only by  a  thin septum,  which is common  tq the 
THE HEART.
179
 two auricles.  On the septum, below its middle, is a super-
 perficial circular depression, the Fossa Ovalis;  it is more
 distinct above than below,  and varies much in its dimen-
 sions.  It is  surrounded by an elevated margin composed
 of muscular fibres, and  called its Annulus, or the Isthmus
 of Vieussens.   The septum of the auricles is thinner at the
 fossa ovalis than elsewhere, and is frequently perforated by
 one or more  foramina: I once met, in  a dissecting room
 subject, with  a hole there,  large enough to transmit the
 finger.   On such occasions,  from the valvular arrangement
 of the opening, it is probable that the blood of the two au-
 ricles is still kept distinct. The fossa ovalis always presents
 this foramen in the foetal state.
   Just below the fossa ovalis is found the Eustachian valve,
 consisting in a duplication of the lining membrane of the
 auricle.  It is crescentic, but varies much in its dimensions
 and shape.   Its left  extremity commences at the left infe-
 rior margin of the annulus ovalis; it then extends itself
 along the front  of the orifice of the  ascending cava; where
 the latter is connected with the auricle, but never to an ex-
 tent sufficient to arrest the circulation there.   Sometimes it
 is reticulated  at its margin, and half an inch wide; on other
 occasions, it  is scarcely developed.   Its loose edge looks
 upwards, and to the right side.  Its office in  the  foetus is
 clearly, according to the opir:~.i of Sabatier, to direct the
 blood of the  ascending cava through  the foramen ovale.
 In the  adult  it may, on  the  general  principle of venous
 valves, oppose  itself to  the  introduction of refluent blood
 into the ascending cava;  but this office cannot be very im-
 portant, as the valve is  frequently scarcely visible  at that
 age.
   At the lower  part of the right auricle, just to the left of
the Eustachian valve and very near it, is the orifice of the
large coronary vein of the heart; it is protected by a small
 semilunar valve, (Valvula Thebesii,) formed also by a du-
plication of the  lining membrane of the auricle.   This ori-
fice will admit a quill of common size very readily.
   Between the right auricle  and ventricle is a round hole, 
180
CIRCULATORY SYSTEM.
of more than an inch in diameter, for the passage of the
blood; it is the Ostium Venosum.   Its  margin,  on the au-
ricular side, is smooth and rounded.
  The parietes of the right auricle are formed by muscular
fibres.  On the sinus these fibres are collected into small
transverse fasciculi, called Musculi Pectinati, from their re-
sembling the  teeth of  a  comb.  These fasciculi, though
slightly united by other  fibres,  yet leave between them
deep  interstices,  by which the external and the internal
membrane   of  the  heart  come  into  contact.   The pari-
etes of the auricle are muscular,  and about one line in
thickness.   Its muscular structure is continued, for a short
distance, on the  two venae cavae.   There are several ori-
fices of small veins on  the internal surface of this cavity,
and in greater abundance  around the fossa ovalis; they be-
long to the system of coronary vessels, and are the forami-
na Thebesii.

  The Right Ventricle  (Ventriculus Dexter, anterior.)
The general form of this cavity, which receives the blood
from the right auricle, is  that of a triangular pyramid, in-
clined somewhat  backwards,  and having  its base down-
wards.  It forms the greater part of the anterior surface of
the heart,  and is about three lines in thickness.   It  is
bounded on its posterior  face by the  left  ventricle, from
which it is completely separated by a thick septum.
  The internal surface of  this  cavity is covered by muscu-
lar  fasciculi of very irregular shapes and dimensions, de-
signated under the term of Columnae Carneae; some of the
latter go from one side to the other; others contribute to the
mechanism  of the valvular apparatus between it and the
right auricle; but  the greater portion is employed in form-
ing a complicated reticular texture over the internal face of
the ventricle.   Those connected with the valves vary from
four to eight  in  number, they are rounded, of different
lengths and sizes, and detach  from their projecting extre-
mity several small rounded tendinous chords, (chordae ten-
dine^) which are inserted into the  floating edge of the 
THE HEART.                   181
valve.  These chords sometimes form an intertexture among
themselves.
  The Valve, between the ventricle  and the auricle, con-
sists in a duplicature of the lining membrane of the ventri-
cle, arising uninterruptedly from around the ostium veno-
sum, at the left margin; which is there somewhat tendinous.
This valve is called the Tricuspid, (Valvula tricuspis, tri-
glochis,)  because its loose margin  is  divided into three
points or processes.   One  of these points, which is at the
anterior external margin of the orifice, is much larger than
the other two; and more distinct in  its  boundaries.  The
edges of these processes form a sort of reticulated work
along with  the adjoining  ends of the tendinous chords;
by this arrangement they are always kept expanded, and in
the cavity of the ventricle.
  The opening  for the  pulmonary artery is placed above
the ostium venosum; at this point the cavity of the ventri-
cle,  instead of being reticulated, is  made smooth, for the
more ready transmission of blood.   The orifice of the pul-
monary artery is round, and about twelve lines in diameter;
it is  furnished with  three valves, called from their shape
Semilunar or Sigmoid.  Each valve is a semicircular plane,
formed from the lining membrane of the  artery, and at-
tached to the latter  by its semi-circumference.   The dia-
meter of the plane is loose, and, instead of being straight,
has each semi-diameter of a curved or festooned  shape; in
the centre of its edge is a small cartilaginous body, the Cor-
pusculum Aurantii, which, when the  valve is thrown down
by the reaction  of the  artery, comes in contact with the
corresponding bodies of the other valves, so that they serve
as mutual  abutments.   Between the outer face  of each
valve and the artery there is a pouch, attended with a slight
dilatation  of the  artery,  and called the Sinus of Valsalva.
Between the  coats of each valve there  is  an additional
fibrous substance, for the purpose of strengthening it.

  The Pulmonary Artery, immediately after  its origin,
goes upwards and backwards to the under part of  the cur- 
182
CIRCULATORY SYSTEM.
 vature of the aorta, and there divides into two trunks, one
 for each lung.   These  trunks separate widely,  and  from
 the middle of their fork proceeds a ligamentous  substance,
 the remains of the Ductus Arteriosus of the foetus, to the
 aorta posteriorly to the origin of the left subclavian artery.
 The right pulmonary artery is both longer and larger than
 the left, and  passing transversely behind the aorta and the
 descending cava, then penetrates the substance of the lung
 to be distributed, as mentioned.   The left pulmonary artery
 passes to the lung in front of the descending aorta.  Though
 the pulmonary artery is quite as  large  as the aorta, its pa-
 rietes are thinner.

   The left Auricle (Auricula  Sinistra, posterior) in the
 natural situation of the heart, is concealed by the right au-
 ricle  and the ventricles.   Its figure is more regularly quad-
 rangular, or square, than that of the right, and into each of
 its angles is introduced a pulmonary vein, there being two
 on each side.  Sometimes, however, the latter join together
 previously, so that the two have but a common orifice.  Its
 tip, or ear-like portion, is situated  at  the  left side of the
 pulmonary artery, and is longer, narrower, more crooked,
 and more  notched  at its margins than the  corresponding
 portion of  the right auricle.
   The parietes of this cavity are muscular,  and  somewhat
 thicker than those of the right;  they are smooth and uni-
 form, both externally and internally,  with the exception of
 its appendix or ear-like portion, in which the musculi pec-
 tinati prevail.   The term sinus venosus or sinus pulmona-
 hVof anatomists; only means that part of the cavity into
which the  pulmonary veins empty.   The septum between
the auricles, when viewed on this side,  has the place of the
fossa ovalis marked out  principally by its diaphanous con-
 dition.  Occasionally there is some appearance of the valve
 which once existed there.
  At the inferior part of the  anterior side of this cavity is
 found the opening between it and the left yentricle, also
 called Ostium  Venosum;  it is circular, and rather more than 
THE HEART.
183
an inch in diameter, resembling strongly the corresponding
orifice of the right side of the heart.

  The Left Ventricle (Ventriculus Sinister, posterior) in
the shape of its cavity resembles a long ovoidal or conical
body.   lis parietes are generally three  times  as thick as
those of the right ventricle, amounting to about eight lines:
it is thicker,  however, at its inferior than at  its superior
part, as it gradually decreases in approaching the .aorta.
  Its internal surface is arranged on the same principle with
that of the right ventricle, being roughened by the presence
of numerous  fleshy columns (Columnae Carneae) some of
which are connected with the valvular apparatus between it
and the left auricle, others form an intricate reticular tex-
ture on its sides, and a few pass from one side to the other.
As this surface approaches the orifice of the aorta, it becomes
smooth, so that no impediment may be afforded to the pas-
sage of the blood.

   The Ostium Venosum, on the side  of this cavity, has its
margin looking tendinous, and furnished with a duplicature
of the lining membrane that surrounds it.   This duplication,
by being severed on its loose edge into two divisions, obtains
the name of Mitral Valve (Valvula Mitralis.)   Its margin
is secured from being pushed into the left  auricle by several
 chordae tendineaj, which are attached by their other extremi-
ties to four or five columnae carneae projecting from the sur-
face of the ventricle.   The whole internal arrangement of
this cavity indicates a great increase  of strength over  that
of the right  side; in the robustness of its fleshy columns, the
number and  size of its tendinous chords, and  the  greater
thickness  of its valve.   The  upper  division of the mitral
valve is placed immediately below the orifice of the aorta,
and is considerably broader than the other, so that when it
 opens to admit blood it is in some measure thrown over the
 aortic orifice.   There is  less of an intertexture among the
 tendinous chords here than on the right side of the heart;
 they cluster more, and, owing to the breadth of the extremi-
 ties of the fleshy columns, are more  parallel. 
1S4              CIRCULATORY SYSTEM.
   The Septum of the Ventricles is of considerable thickness,
 being formed almost exclusively by the continuation of the
 fibres of the left ventricle.   Where the large columnae car-
 neae elevate themselves on  its  surface, its thickness is in-
 creased.  Its shape is somewhat  triangular.   It  forms  a
 round projection into the right ventricle, while its other sur-
 face, which presents to the left, is concave to the same de-
 gree.  It is rather thinner as is  approaches the auricular
 septum than elsewhere.  Its fibres near  the apex are less
 closely connected to each other.
   The Orifice of the Aorta is furnished  with three semi-
 lunar Valves, which, in the mode of their arrangement cor-
 respond  precisely  wTith  those  of the pulmonary  artery.
 They  are however  thicker, and  the  Corpuscula Aurantii
 are larger.   The Sinuses of Valsalva, attended with a slight
 dilatation of the artery, exist in the  same way.  Just be-
 yond the margins of the right and of the left valves are ob-
 served the orifices of the  two coronary arteries.   The ori-
 fice of the  aorta is somewhat tendinous,  which marks out
 the distinction of structure between it and the ventricle.

                  Of the  Pericardium.

   The heart, as stated, is surrounded by its proper capsule,
 called  the Pericardium, which separates it from the adjoin-
 ing parts, and sustains it in its dilatations.  The pericardium
is  covered  on its sides by the pleurae, and reposes on the
tendinous centre of the diaphragm, to which it adheres by
close compact cellular substance, particularly at its periphery.
When the latter attachment is cut through, a separation of
the remainder is easily effected.  Behind, the pericardium
is  opposed to the bronchiae and the oesophagus.
   The pericardium does not adhere to the heart, except at
the base of the latter; it is, therefore, a loose capsule in, by
far, the greater part of its extent.   It not only  surrounds
the heart, but also the  roots of the large arteries and veins
connected with it.  Thus it includes the  aorta, as high up
 as the great  vessels proceeding from its arch; from the lat- 
THE HEART.                   1S5
 ter, it passes to the trunk of the pulmonary artery, and also
 includes it, causing the  aorta and the pulmonary artery to
 lie close together.  The posterior face of these vessels is not
 covered so high up as the anterior  face.  The pericardium
 also invests the descending vena cava for an inch above its
junction with  the right auricle;  it likewise  invests the
 trunks of the pulmonary veins, and  the ascending  cava as
 it rises above the diaphragm.   The pouches which it forms
 at the base of the heart, in passing from one of these ves-
 sels to another, are the cornua of some anatomists.   It can-
 not be considered  as pierced for the passage of these ves-
 sels, but is lost insensibly on their parietes; being continued
 into the cellular covering of the arteries, in  accompanying
 them to a great distance. *
   The pericardium is a double membrane, or consists of two
 layers, an internal and an external one.  The external mem-
 brane,  to which the preceding description is especially ap-
 plicable, resembles strongly the dura mater, but is thinner;
 it is therefore white, semitransparent, fibrous and inelastic.
 Its thickness is greater  on the sides, than below where it
 rests upon the diaphragm, or above, where it goes along the
 great vessels; its  fibres are irregularly disposed and inter-
 woven, but many may be traced longitudinally.
   The internal  membrane lines the external, and gives the
 polish to its cardiac surface; it is then  conducted along the
 surface of the several vessels that have been mentioned, to
the heart, over the whole of which it is spread,  and adheres
to it by cellular substance, frequently containing much  adi-
pose  matter;  it  also  causes  the heart to  have a smooth
shining surface.  This is a very delicate thin serous mem-
brane; and secretes a fluid, transparent and somewhat unc-
tuous, like that of the joints, but not so consistent;  which
lubricates the surface  of the heart and permits it to play
freely within its pericardium.   This fluid, in a natural state,
seldom  exceeds a tea-spoonful though two ounces or a lit-

              • Subatier Trait. d'Anat. vol.  ii. p. 284.
   Vot.. II.—24 
 186              CIRCULATORY SYSTEM.

 tie more are not considered sufficient evidence of a patholo-
 gical state;  its augmentation constitutes a dropsy.
   After death, we find the pericardium lying loosely upon
 the  heart, from the  vacuity, and  consequently diminished
 bulk of the latter; but while  the circulation  is going on
 the heart  fills and distends it.   A striking resemblance is
 observable  between the condition of, the pericardium and
 the  moveable  articulations.   Its  external membrane cor-
 responds with  the strong fibrous  capsule that passes from
 one bone  to the other; while the internal is the synovial
 bag, which  scarcely assists in the strength of the  apparatus,
 but  secretes a fluid to render motion easy.   Several in-
 stances are on record of a total absence of pericardium.


             Of the Texture of the Heart.

   The Heart, with the exception of the membrane  which
lines its cavities, and of the  serous  lamina of pericardium
which covers  its surface,  consists  entirely  of  muscular
fibres.
   The sides of the auricles, as stated, are much thinner
than those of the ventricles.  In the right auricle, the stra-
tum of muscular fibres is uniform in its venous portion, but
on the sinus is  arranged into the parallel fasciculi  called
the Musculi Pectinati: a circular  fasciculus surrounds the
 orifice of the descending cava.  In the left auricle, the stra-
tum of muscular fibres forms a uniform layer, and  is also
thicker than on the right side.   These  fasciculi commence
 on the pulmonary veins and run transversely across the au-
ricle, with the  exception of the more deeply seated, which
are irregular, and  crossed upon each other.   The septum
of the auricles is also formed by a  muscular stratum.
   In the ventricles, the superficial fasciculi observe a spiral
course, and  many of those belonging to the left ventricle
may be traced over the right; as the fibres are more deeply
situated, they become  shorter and more  interwoven.  In
the septum,  between the ventricles, the fibres of the two ca-
vities are  much interlocked; but,  with some trouble, may 
THE HEART.
187
be separated.  The fibres of the columnae carnae are too ir-
regular in their  course to admit even of a general descrip-
tion.


          Of the Blood  Vessels of the  Heart.

  The Heart is  furnished  with both  arteries  and veins,
which belong to its nutritious system.
  The arteries called Coronary arise, as observed, from the
trunk of the aorta,  somewhat above the margins of  the se-
milunar valves,  so  that when the latter are applied  against
the aorta, the orifices of these arteries  are still visible.

  The Right Coronary Artery begins above the anterior
valve, and passes to  the  right, beneath the pulmonary ar-
tery; it then shows itself in the upper part of  the fissure,
between the right auricle and right ventricle, and follows
the course of this fissure to the  flat side of the heart.  It
detaches, as it  goes  along, several small branches, which
come off at right angles from it.  One set of these branches
is distributed upon the right ventricle, and another set upon
the right auricle.   Small branches are also sent from it to
the root of the pulmonary artery, and  to that  of the  aorta.

  The Left Coronary Artery begins above the left semilu-
nar valve.  While its root is still obscured by  the pulmo-
nary artery, it divides into two principal branches, of which
the anterior runs in the fissure on the upper part of the sep-
tum of the  ventricles to the apex of the heart, and  in this
course distributes branches  to the  right and left   ventri-
cles;  those  to the  right anastomose with the branches  of
the right  coronary artery, which go to the  same ventricle.
The other branch goes along the  groove, on the septum,
between  the left auricle  and left ventricle, and reaches the
under surface of the  heart; and  in  this course  distributes
many branches to the left auricle and left ventricle, both on
their upper and under surfaces.  It anastomoses freely with
the branches of the trunk that runs along the upper  part
of the septum. 
 18S              CIRCULATORY SYSTEM.

   In consequence of the  frequency of the anastomoses be-
 tween the two coronary  arteries, injecting matter thrown
 into one very readily finds its way into the other.

   The Coronary Veins receive the blood, which is distri-
 buted by the coronary arteries  through the substance of the
 heart.

   The Great Coronary Vein (Vena Coronaria Maxima
 Cordis) is formed by the union of several trunks, which
 run from the apex towards the base of the heart.  One of
 them begins at the apex,  goes  along the superior fissure of
 the septum of the ventricles, and then winds to the left side,
 between  the left  auricle  and the left ventricle; while in
 the latter position, it is joined by several trunks coming
 from the left ventricle and the left auricle; it finally emp-
 ties into the lower part of the right auricle, just in front, as
 mentioned, of the orifice of the ascending cava; being there
 covered by its own valve.

   The Lesser Coronary Vein (Vena Coron. Minor Cordis)
 lies in the inferior fissure of the  septum of the ventricles.
 It begins at the apex, and,  going  backwards, collects the
 blood from the flat surface of the heart, principally on  the
 right ventricle.   It discharges into the great coronary vein,
just before the latter terminates in the auricle.

   Besides the preceding veins,  some of  a smaller size exist
 on the right ventricle, and about the root of the  aorta and
 pulmonary artery, and empty by several orifices into  the
 right auricle.  There are also some veins of a still smaller
 size, which open into all  the cavities of the heart by little
 orifices,  called the foramina of Thebesius; by Mr. Aber-
 nethy they are considered as being larger when  the lungs
 are diseased.*

   The Nerves of the Heart come principally from the cer-
 vical ganglions of the sympathetic, and  follow the course
* London Philosophical Transactions, 1798. 
THE HEART.
189
of the coronary arteries.  It has been doubted whether these
nerves are actually distributed in the substance of the heart,
from the presumption, that as they cannot be traced beyond
the third order of branches of the coronary arteries, they
are limited to them.   But, as the ramifications of the sym-
pathetic are bestowed exclusively upon the branches of the
circulatory  system,  Meckel has very properly suggested,
that the heart being also supplied with  nerves from the same
source, it follows that  there can be no departure from the
general rule, as the  heart is nothing more than the fibrous
portion of the blood vessels more completely developed.

   While the circulation continues, as both auricles contract
at the same instant, whereby the blood  is thrown into the
ventricles;  and as immediately  afterwards the ventricles
contract simultaneously  also, whereby the blood is  forced
into the aorta and the pulmonary artery; so it is the con-
traction of  the ventricles which  causes  the heart to strike
against the parietes of the thorax. For, as was first pointed
out by Dr. W. Hunter, the  blood which is forced through
the large arteries, by extending them  diminishes their cur-
vature, or brings them  more into a straight line, in which
effort the heart bounds up from the tendinous centre of the
diaphragm.  The filling of the auricles,  while this is going
on, also assists  in  protruding the heart forwards.  The
French anatomists assert, that during the contraction of the
ventricles, their  extremity is elevated or bent upwards on
the body of the heart, which will also  increase the momen-
tum of the stroke against the thorax. 
190
CIRCULATORY SYSTEM.
                     CHAPTER II.

                   OF THE ARTERIES.

   SECT. I.--THE AORTA AND THE BRANCHES FROM ITS
                       CURVATURE.

   The Aorta is the trunk of the arterial system.   Having
arisen from the superior posterior end of the left ventricle,
its root passes beneath the pulmonary artery, and is entirely
concealed in front by it.   Keeping  to the right it emerges
from  the base of  the  heart, between the  right auricle and
the trunk of the  pulmonary artery, being bounded on the
right side by the Descending Cava.  Continuing its ascent,
it  forms a  curvature with the convexity upwards, and the
summit of which  rises to within eight or twelve lines of the
superior edge of the sternum.  This curvature is in front of
the third  and fourth dorsal vertebrae, and its  direction is
nearly marked out by a line drawn from the anterior extre-
mity  of the third right rib, to the posterior end or tubercle
of the third one on the left side.   In this course, therefore,
the aorta passes over the right pulmonary artery, across the
left bronchia, and applies itself to the left side of the spine,
about the third or fourth dorsal vertebra.   It is this curva-
ture which obtains the name of the Arch of the Aorta (Ar-
cus Aortas.)
   Near its origin, where the aorta is still within the peri-
cardium, it has very commonly,  especially in persons ad-
vanced in age, a dilatation, which is  called the great sinus,
to distinguish it from the lesser  sinuses,  or those of Val-
salva.  The ascending portion of  the arch is to  the right  of
the vertebral column, the descending portion to the left, and
the middle or horizontal part goes in front of the trachea.
   The Aorta, in  its descent  down the thorax,  is placed  in
the posterior mediastinum, and is covered on one side by
the left pleura, while the other side is in contact with the 
       BRANCHES FROM THE ARCH OF THE AORTA.     191

left surface of the bodies of the dorsal vertebrae.  At the
lower part of the thorax it inclines towards the middle line
of the vertebrae, in order to reach the hiatus aorticus of the
Diaphragm, through which  it penetrates  to  the  abdomen.
In the abdomen it descends in front of the lumbar vertebrae,
somewhat inclined to their left side;  and  at the interverte-
bral space between the fourth and fifth vertebrae of the loins,
or somewhat above it, it ceases, by being  divided into two
large trunks, the Primitive Iliacs; one for  each lower extre-
mity, and the corresponding side of the Pelvis.
   In this course of the aorta from the heart to the loins, it
first gives off the branches which supply the head and the
superior extremities; then, those which supply the sides of
the thorax;  afterwards, in the  abdomen, it detaches the
trunks which supply the viscera and the  sides of the latter
cavity.

   The  Coronary Arteries are, strictly speaking, the first
branches of the aorta, but as they belong especially to the
heart, their  description is  associated with it.   In all the
space between them and the superior  convexity of the aortic
arch no  branches are given off; but as the aorta is crossing
the trachea three considerable trunks  arise from it, which
are distributed upon  the head and  the  upper extremities
principally.   They  are, the Arteria  Innominata, the Left
Primitive Carotid, and the Left Subclavian.

   The Arteria Innominata is first in its origin, in ascend-
ing from left to right in front of the trachea, and behind the
transverse vein, it  crosses the trachea very obliquely; is
from an inch to an inch and a half, and sometimes, though
rarely, two inches long, when it divides  into the right sub-
clavian and the right primitive carotid. The left primitive
carotid arises from the aorta,  close upon the left border of
the innominata, frequently, indeed, from  a part of it.  The
left subclavian, though at its  origin  near the left carotid,
 generally leaves a  distinct interval of one,  two, or three
 lines.  The relative  situation of these trunks is particularly 
192
CIRCULATORY SYSTEM.
 alluded to in the account of the superior mediastinum. The
 two last are of course longer that the corresponding trunks
 of the right side, by the whole length of the arteria inno-
 minata.  With the exceptions connected with their mode
 of origin, the arterial trunks  of  the two sides are exactly
 alike, and have the same mode of distribution.

   The Common Carotid Artery (Carotis Primitiva) being
 a branch of the innominata on the right side, and of the
 aorta on the left, goes up the neck to terminate just below
 the cornu of the os hyoides. In the early part of its course
 the right one is more inclined outwardly than the left, owing
 to its origin from the  arteria innominata in front of, and to
 the right side of the trachea, whereas the left ascends almost
 vertically.
   At the lower part of the neck, just above the sternum and
 the clavicle, the carotid is covered by the sterno-hyoid and
 thyroid  muscles, and  by the sternal portion of the sterno-
 cleido-mastoid.  It is  crossed obliquely on a line with the
 lower part of the thyroid cartilage or of the larynx, by the
 omo-hyoid muscle.  It lies at the side of the thyroid gland,
 the trachea,  the larynx, the oesophagus, and  pharynx, in
 front of the transverse processes of the cervical  vertebrae,
 and the longus colli muscle; having on its outer margin, but
 somewhat in front,  the internal jugular vein and the pneu-
 mogastric nerve enclosed in the same sheath, and the sym-
 pathetic nerve behind.  At the side of the larynx the ca-
 rotid is very superficial, and with the  exception of being
 crossed by the omo-hyoideus muscle, it is only covered by
 the platysma myoides and the integuments.

   The Carotid having got as high as the space between the
 os hyoides and the  thyroid  cartilage, but varying slightly
 in different subjects, there divides into two large trunks, the
Internal Carotid, which goes to the brain and to the eye,
and the External Carotid, which is principally distributed
upon the more superficial parts of the head and neck. The
first of these trunks is placed behind the other, and bends
 outwardly at its root: it is generally the largest in infancy, 
            CAROTIDS AND THEIR BRANCHES.         193

on account of the proportionate volume of the brain at that
age; it is also swollen at its root, so as to form a sinus there
resembling an  incipient aneurism.  No branch,  except in
anormal  cases, is given off from the carotid  between its
origin and this bifurcation.


    SECT. II.--OF THE CAROTIDS AND THEIR  BRANCHES.

  The Internal Carotid (Arteria Carotis Interna) in the
adult is  smaller  than the external, and extends from the
larynx to the sella turcica. It ascends between  the external
carotid and the vertebrae of the neck,  being in front of the
internal  jugular vein, and having the pneumogastric nerve
at its outer margin; as it gets on a level with the base of the
lower jaw, it is crossed externally by the digastric and the
stylo-hyoid muscles; it is immediately afterwards concealed
in  the subsequent part of its ascent  by the ramus of the
lower jaw. Having gone along the most internal or deeply
seated margin of the  parotid gland and the styloid process
of the temporal bone, at the side of the superior constrictor
of the pharynx, it then penetrates into the cranium through
the carotid canal of the temporal bone.
   It is slightly flexed between its origin and the  carotid
 canal; just before it reaches the latter it curves upwards and
 forwards.  The  first part of its course through the canal is
vertical, afterwards it goes horizontally forwards;  and  to
escape from the  canal it has once more to ascend almost
vertically, which brings it to the posterior extremity of the
Sella Turcica.  On the side  of the Sella. Turcica it again
passes horizontally forwards  through the cavernous sinus;
and at the anterior  clinoid  process it once more ascends,
and having penetrated the dura mater it reaches the brain.
   In this passage through the carotid canal it is attended by
the upper extremity of the  sympathetic nerve,  and gives
 one or more small  branches  to  the petrous bone;  it also
 gives a few branches  to the dura  mater and to the nerves
 about the cavernous sinus.   But for  the full exposition of
   Vol.  II.—25 
194
CIRCULATORY SYSTEM.
the distribution of the internal carotid see the articles Brain
and Eye.

  The External Carotid Artery (Carotis Externa) extends
from the termination of the primitive carotid, to the neck
of the lower jaw.  In  the early part of its course, where
it is situated in front of the  internal carotid, and between
the pharynx and  the sterno-mastoid muscle,  it is compara-
tively superficial, being only enveloped by its sheath, and
covered by the platysma myoides and the skin. Just above
this place it is crossed externally by the hypoglossal nerve,
which detaches the  descending branch along the front of
its sheath and of  that of the primitive carotid.  Somewhat
above this nerve  it is also crossed externally by the digas-
tric and the stylo-hyoid muscle, and lies there on the side
of the superior constrictor muscle of the pharynx, near the
tonsil gland.   About its middle it is  crossed internally by
the stylo-glossus  and the stylo-pharyngeus muscle;  it then
ascends through  the  substance of  the  parotid gland, be-
tween the ramus  of the  lower jaw and the ear, to its termi-
nation.

   Several very important branches are given off from the
external carotid;  they are as follow:
   The Superior  Thyroid Artery (Art. Thyroidea  Supe-
rior) arises from  the external carotid,  about a line above
its root, and is distributed to the larynx and  to the thyroid
gland.   It goes at first  inwards and forwards on the side of
the larynx, being covered by the omo-hyoideus muscle, and
by the platysma  myoides, it then descends under the ster-
no-thyroideus to  the  upper  margin of the lobe of the thy-
roid gland.   In this -course it performs  several flexuosities,
of considerable variety in different ^individuals.
   The Laryngeal Branch comes from  it near the superior
margin of the thyroid  cartilage; this branch glides in be-
tween the thyreo-hyoid muscle and  the membrane of the
 same name; after a short course it penetrates the latter, and
 is then distributed in a great  number of small twigs to the 
CAROTIDS AND THEIR BRANCHES.         195
muscles and to the lining membrane of the larynx.  A small
trunk, either from the laryngeal branch, or from the thy-
roid artery itself,  is spent upon the crico-thyroid muscle,
and traversing the front surface of the middle crico-thyroid
ligament anastomoses with its fellow: small twigs from this
branch penetrate  to  the interior of the  larynx through the
crico-thyroid ligament.  Sometimes this crico-thyroid ra-
mus is superior in size to the one above, in which case  it
princip lly supplies the interior of the larynx.
  The Thyroid Branch  is the  continuation of the princi-
pal trunk;  it penetrates  into the substance of the thyroid
gland, and divides into two  ramuscles, one of which goes
along the posterior face of the  lobe of the gland, and anas-
tomoses with the inferior thyroid; the other goes along the
upper margin of the gland,  and anastomoses with its con-
gener of the opposite  side.   The thyroidal  artery is split
up into a great many branches in the substance of the gland,
it also sends small branches to the pharynx, oesophagus, and
the little muscles on the front of the neck.

  The Lingual Artery (Art. Lingualis) comes from the
external carotid at the distance of from six to twelve lines
above the superior thyroid,  and goes to the tongue.  It  is
concealed in the early part of  its course by the digastric
and the stylo-hyoid  muscles; it then penetrates the hyo-
glossus muscle just above the  cornu of the os hyoides, or
goes between it and the middle constrictor of the pharynx;
it then ascends between the hyo-glossus and the genio-hyo-
glossus muscle; advancing forwards,  it is placed  between
the latter and the sublingual  gland, and finally reaches the
tip  of the tongue.
  The lingual artery sends off the following branches.  At
the root of the tongue one  or  more  trunks arise  from  it
(Dorsales Linguae) which go  to the  base of this organ,
the tonsils,  the  palate,  and  the  epiglottis.   A  little fur-
ther on, this artery detaches another branch (Ramus Sub-
lingualis) which advancing  between the -mylo-hyoid aud
the  genio-hyo-glossus muscles,  and  above  the sublingual
gland, detaches a great many ramifications  to these parts 
196              CIRCULATORY SYSTEM.
and to the lining  membrane of the  mouth; it is sometimes
a branch of the facial.   The Ramus Raninus,  is the conti-
nuation of the lingual;  it advances  between the lingualis
and the genio-hyo-glossus muscles, to the tip of the tongue,
distributing continually its twigs on each margin, and ends
there by anastomosing with  the corresponding artery of the
other side.

  The Facial Artery (Arteria Facialis,  Maxillaris Ex-
terna) arises from the external carotid, two or three lines
above the lingual, and is spent principally on the side of
the face below the eye.   It is of considerable size, and very
tortuous; its root is concealed by the stylo-hyoid and the
digastric muscles, and it is traversed externally by the hy-
poglossal nerve.  It goes forwards within the angle of the
lower jaw and above the submaxillary gland, but very much
connected with it: it then mounts over the base of the max-
illa inferior, at the anterior margin of the masseter muscle,
and  afterwards shapes its course, in a serpentine manner,
to the internal canthus  of  the eye, passing between the
muscles  and  the  integuments of  the face.   In this course
the facial artery sends off the following branches.
  As it passes by the submaxillary gland it sends several
twigs to it: previously it also sends several little branches
to the contiguous muscles,  as the internal pterygoid, di-
gastric, and so on, but they are too small to be of much con-
sequence.
  The Submental branch arises,  then,  on a level with the
base of the lower jaw; it advances forwards under the ori-
gin of the mylo-hyoideus,  and above the anterior belly of
the digastricus.   It  sends several ramuscles to these mus-
cles,  some of which anastomose with  the ranine  artery;
behind the symphysis of the jaw it anastomoses with its
fellow, it then mounts over the  chin, to which and to the
lower lip it is distributed, anastomosing there with the in-
ferior coronary artery of the  mouth, and with the inferior
maxillary which  comes out  from the anterior mental fora-
men in the lower jaw.
   When the facial  artery has got upon the face, it sends 
            CAROTIDS AND THEIR BRANCHES.         197

backwards a small branch to the lower part of the masseter
muscle.   Somewhat above this it sends forwards a branch
called the Inferior Labial, which is distributed upon the mid-
dle of the chin.  When it  gets on a level with the corner
of the mouth,  but sometimes lower down, it sends for-
wards, under the depressor  anguli oris, the  Inferior Coro-
nary Artery, to  the  lower lip, which frequently supplies
the place of the inferior labial entirely; but when the  latter
is large the  coronary is  small  in proportion:  a few lines
higher up the facial sends forwards a third branch,  the Su-
perior Coronary, which goes to  the upper lip.  These coro-
nary arteries are very tortuous, and are distributed by  many
 branches in the substance of the lips: by anastomosing with
 their congeners of the other side, they surround the mouth
 completely.    The superior  coronary artery,  as  it passes
 under the nose, sends upwards  one or more small branches
 to the integuments of its orifice and septum.
   After this, the facial artery, in ascending towards the in-
 ternal canthus  of the eye, sends a branch to the ala nasi, and
 another  to anastomose with the  infra-orbitar artery.   It
 finally terminates at  the internal canthus of the eye by anas-
 tomosing with the branches of the ophthalmic, which come
 out there upon the side of the root of the  nose.  Several ra-
 muscules, which are too small to merit special description,
 are given by the facial to the integuments and muscles  of
 the face, and to  the lower eyelid.

    The  Inferior  Pharyngeal  Artery (Art. Pharyngea In-
 ferior,  ascendens) is one  of the  smallest of the original
 branches of the external carotid, and generally arises oppo-
 site to  the lingual;  but there is much variety in the latter
 respect, it being sometimes higher up or lower down, and
 not unfrequently a branch of one  of the other arteries, in-
 stead of being an original trunk.  It ascends on the side of
 the pharynx,  between the external  and the internal carotid,
 and is covered by the stylo-pharyngeus muscle. It is prin- '
  cipally distributed on the constrictor muscles of the pharynx,
  and upon their lining membrane.   But one of its branches,
  called  the  Posterior  Meningeal Artery,  ascends through 
198
CIRCULATORY SYSTEM.
 the posterior foramen lacerum of the cranium, between the
 jugular vein and the pneumo-gastric nerve, and is distri-
 buted on  the contiguous dura-mater.

   The Occipital Artery (Arteria Occipitalis) is a very con-
 siderable trunk, which comes from the external carotid, gene-
 rally opposite to the  facial, and is spent upon  the  integu-
 ments, on the back part of the head.
   At its root, it is deeply situated in the side of the neck, be-
 low the parotid gland, and has the internal jugular vein and
 the par vagum on its inside.  It goes obliquely backwards,
 in ascending along the posterior belly of the digastricus, be-
 tween the transverse process of the atlas and the mastoid por-
 tion of the temporal bone, being covered by the several mus-
 cles which are inserted into the latter, as the sterno-mastoid,
 the splenius; and the trachelo-mastoid.   It is covered, for
 some distance, by the insertion of the splenius capitis, and
 becomes at length superficial at the posterior margin  of this
 muscle.   The occipital artery is distributed as follows:
   Shortly after its origin, it sends branches to the digastric
 muscle behind, to the upper part of the sterno-mastoid and
 to the lymphatic glands of the upper part of the neck.  While
 enclosed by the muscles on the back of the neck, it also sends
 branches to them, and anastomoses thereby with the vertebral
 artery; occasionally, one of these branches is of considerable
 magnitude, and has been found descending very low  on the
 back, between the splenius and the complexus muscles.   It
 also sends a small branch to the dura mater, through the
 mastoid foramen generally, but sometimes through the pos-
 terior foramen lacerum.  When the stylo-mastoid artery is
 wanting, it also detaches a branch through the stylo-mastoid
foramen to the internal parts of the ear.
  The occipital artery, having become superficial at the in-
ternal margin of the splenius on the occiput, ascends  on the
latter bone towards the vertex in a tortuous manner, sending
off, on each side, many small ramifications.   It ends by anas-
tomosing with the posterior  temporal artery.

  The Posterior Auricular Artery (Art. Auricularis Poste- 
CAROTIDS AND THEIR BRANCHES.         199
rior) arises a little above the last, at the lower edge of the pa-
rotid gland, from the external carotid, and is one of its small-
est branches.   It ascends backwards enclosed by the parotid
gland, and afterwards between the meatus auditorius exter-
nus and the mastoid bone; at the latter place, it sends a ra-
mification to the internal side of the external ear; it then
ascends and is distributed, by small branches, on the conti-
guous integuments of the side of the head.   While still in-
volved in the parotid gland, it sends some small ramifications
through the meatus externus  to its lining membrane and the
membrana tympani.  It then detaches a branch through the
stylo-mastoid foramen, from  which the whole artery is also
named Stylo-Mastoid; but this branch, as stated, sometimes
comes from the occipital.  The stylo-mastoid passes along
the aqueduct of Fallopius, detaching its arterioles to the
tympanum and to the labyrinth.

   The External Carotid having detached these trunks, pe-
netrates vertically through  the middle of the parotid gland,
and gives to it  several small twigs.  When it arrives on a
line with the neck of the lower jaw, it  divides into two
large trunks; one of them, the Internal Maxillary, goes to
the parts within the ramus of the lower jaw; the other, be-
ing smaller, is the Temporal Artery.

   The Temporal  Artery (Arteria Temporalis) continues
to ascend through the substance of the Parotid, but  becomes
superficial in front of the meatus externus, in mounting over
the root of the zygoma; it is  then distributed to the integu-
ments on the side of the head.
   It frequently sends  off one or two ramifications, of but
little volume, to the masseter muscle.  Just above its root,
and while surrounded by the parotid, a branch of some im-
portance, the Transversalis  Faciei,  leaves it, and crosses
horizontally the  masseter  muscle, just below the Parotid
Duct, sometimes above it.  This branch is distributed to the
adjacent integuments  and muscles, and terminates in front
by anastomosing with the facial and the infra-orbitar artery.
   A  little below the zygoma, the Middle Temporal Artery 
200
CIRCULATORY SYSTEM.
comes off from the Temporal, and, ascending with the pa-
rent trunk, perforates the temporal fascia at the upper mar-
gin of the zygoma, and is distributed to the temporal mus-
cle by many ramifications, which anastomose with the deep-
seated temporal arteries.   After this, some  small twigs,
called Auricular, go  to the external  ear from the trunk of
the Temporal  Artery.
   The Temporal Artery having ascended for an inch  or so
between the aponeurosis  of the temporal muscle and the
skin, divides it into  an Anterior and a Posterior Branch.
The former ascends  towards the  side of  the os frontis,
and is distributed in ramuscles to the orbicularis palpebra-
rum, the belly of the occipito frontalis, and the integuments
of the front of the cranium, anastomosing with the frontal
artery and  the temporal of the other side.  The Posterior
Branch  is distributed  on the integuments of the middle of
the side of the cranium,  anastomosing  with  the  anterior
branch,  with its fellow of the other side, and with the oc-
cipital artery.

   The Internal Maxillary  Artery (Arteria Maxillaris In-
terna) winds around the neck of the lower jaw, and passing
between the pterygoid muscles, proceeds in a tortuous  man-
ner to the deepest points of the zygomatic fossa.  The first
part of its course is horizontally inwards; it then ascends in
front of the pterygoideus externus to the bottom of the tem-
poral bone, or  the spinous process of the sphenoidal; it then
passes forwards, within the temporal muscle,  to the upper
part of the pterygo maxillary fossa.
   It sends  off several branches, and  commonly in the fol-
lowing order:
   1. The Arteria Tympanica, to the  tympanum, through
the glenoid fissure.
   2. The Arteria  Meningea  Parva,  to the  dura mater,
through the foramen ovale. It is most frequently a branch
of the next.
   3. The Arteria Meningea Magna, or Media, to the dura
mater; through the foramen spinale.   This branch having
entered the cranium, is distributed upon the dura mater in 
CAROTIDS AND THEIR BRANCHES.         201
the manner  marked off by the furrows upon  the  internal
face of the temporal, the parietal, and the frontal bones.
One of its branches enters the aqueduct of Fallopius, through
the Vidian Foramen, and  is distributed upon  the  internal
parts of the organ of hearing,  anastomosing with the stylo-
mastoid artery.
   4. The Arteria Maxillaris, or Dentalis Inferior, descends
along the internal face of  the ramus of the lower jaw, and
having sent off some ramifications of small size to the conti-
guous muscles and the lining membrane of the mouth, it
enters the posterior mental foramen with the inferior dental
nerve.  Going along the canal in the substance of the lower
jaw,,it  detaches successively from its superior margin ra-
mifications to the teeth.  At the anterior mental foramen a
trunk is sent forward as far as the symphysis, which sup-
plies  in its course the canine and incisor teeth;  the re-
mainder of  the inferior maxillary artery  comes out at the
foramen, and supplies the  chin, anastomosing with the facial
artery.
   5. The Arteriae Temporales Profundae are two in number.
The first of them, called  posterior, arises next to the infe-
rior maxillary. It is concealed between the external ptery-
goid and the temporal muscle for some  distance; it then
ascends in the posterior part of the temporal fossa, beneath
the temporal  muscle, and is minutely distributed upon it.
The anterior  deep temporal artery  is separated  from the
posterior, in its origin from the internal maxillary, by the
pterygoid and the buccal arteries.  It arises near the ptery-
go-maxillary  fossa, and ascending between the  temporal
muscle and the fore part of the corresponding fossa, it is mi-
nutely distributed upon the former, anastomosing with the
posterior deep, and with the middle temporal artery.
   6. The Arteriae Pterygoideae  arise after the  posterior
deep temporal. They vary considerably in regard to num-
ber, size, and  origin, and are distributed  upon the ptery-
goid muscles, as their name implies.   One of their branches
which is sometimes an independent trunk from the internal
maxillary, goes between the posterior margin of the tem-
   Vol. II.—?f> 
202              CIRCULATORY SYSTEM.

poral muscle and of the neck of the lower jaw, in front of
the latter, to be  distributed upon the internal face of the
masseter muscle.
  7.  The Arteria Buccalis, sometimes a branch of the in-
ternal maxillary, but frequently  coming  from one of its
trunks, either the alveolar or the  anterior  temporal, passes
along the external face of the upper jaw, and distributes its
branches to the buccinator  and  zygomatic muscles, and to
the lining membrane of the mouth.
  8.  The Arteria Maxillaris, Superior,  or Alveolaris, pro-
ceeds downwards and forwards in winding around the tuber
of the upper jaw bone.   It first  sends  some ramifications
through the bone to the roots of the great and small molar
teeth, and to  the lining membrane of the maxillary sinus; it
then passes forwards  along the gums, near the buccinator,
and gives ramifications to them and to the contiguous mus-
cles.
  9.  The Arteria Infra-orbitalis  comes from  the internal
maxillary, at the upper part of the pterygo-maxillary fossa;
it sends some inconsiderable ramifications to the fat and the
periosteum of the orbit,  through  the spheno-maxillary fis-
sure.   It then  enters the  infra-orbitary canal, and passes
through it with the infra-orbitary nerve.  On arriving near
the anterior orifice of the canal,  it detaches downwards a
branch which goes to the canine and the incisor teeth, and
to the lining membrane of the antrum.  It then gets to the
face below the origin  of the levator labii superioris muscle,
and is distributed upon the muscles in  front of the upper
maxilla, anastomosing with the facial and with  the ophthal-
mic artery.
   10.  The Arteria Palatina Superior descends through the
posterior palatine canal,  and having  reached  the mouth,
leaves some ramifications with  the soft palate; it then ad-
vances between the bones and the lining membrane of the
roof of the mouth, and disperses itself in several small twigs,
one of which passes through the foramen incisivum into the
nostril.
   11. The  Arteria  Pharyngea Superior  is  sometimes  a 
SUBCLAVIAN AND ITS BRANCHES.          203
branch of the last, and is spent upon that portion of the
pharynx bordering on the pterygoid processes.
  12. The Arteria Spheno-Palatina is the terminating trunk
of the internal maxillary; it  enters the nose through the
spheno-palatine foramen, and divides into two  branches,
which are minutely distributed over the Schneiderian mem-
brane.  One of them descends along the  septum narium;
the other along the external margin of the posterior naris,
and divides into two principal ramuscles, one of which  is
dispersed along the middle turbinated, and the other along
the inferior tubinated bone.
       SECT. III.--OF THE SUBCLAVIAN  ARTERY AND IT:i
                           BRANCHES.

      The  Subclavian Artery  (Arteria Subclavia) of the
    right side having arisen from the innominata, and that of
    the left from the aorta, they each go over the first rib of their
    respective side, adhering closely to it, in the bottom of the
    interval between the scalenus anticus and medius  muscles.
    The right subclavian is much shorter, and more superficial
    than the left, from its origin to the scaleni muscles.  Near
    the latter they are each covered in front by the sternal end
    of the clavicle, by the  sterno-hyoid  and  thyroid  muscles,
    and by the subclavian  vein of the corresponding  side; be-
    hind they are separated from the  vertebral column by the
    longus colli muscle; below them is the pleura, the left ar-
#   tery being in contact with  it for its  whole passage  in the'
    thorax; and on their internal  side is the primitive carotid.
    The subclavian  of the right side is crossed near the scale-
    nus anticus by the par vagum; the phrenic nerve also goes
    in  front of it, but on  the internal edge  of the  scalenus.
    The subclavian of the left side having a course almost ver-
    tical from its origin to  the interval of the scaleni muscles,
    is nearly parallel with, and behind, the primitive carotid of
    that side; the phrenic nerve has the same relative position
    with it as on the right side; but the par vagum goes paral- 
204
CIRCULATOR t" SYSTEM.
lei with, and in front of the subclavian artery,  for some
distance along the root of the latter.
  At the inner margin of the Scaleni Muscles the Subcla-
vian  gives off a  cluster of trunks, to wit; the Vertebral;
the Inferior Thyroidal; the  Superior Intercostal;  the  In-
ternal Mammary; and the Cervical Artery.  They some-
times arise distinctly, and  after the order mentioned;  but
there is too great a  diversity in subjects  to  establish any
rule on  these points.

  1.  The Vertebral Artery  (Arteria Vertebralis) is  the
most voluminous of the branches of the Subclavian.  Im-
mediately after its origin it ascends on the side of the spine
and enters the canal of the transverse processes of the neck
at the sixth vertebra.  Pursuing this  course it gets  into the
cavity of the cranium through the foramen magnum occipi-
tis, and is distributed to the brain in the manner mention-
ed in the description  of that  organ.
  While in the  canal of the  transverse processes it sends
off  several branches  to the  heads of the contiguous mus-
cles,  and to the medulla spinalis of the neck.

  2.  The  Inferior Thyroid  Artery  (Arteria Thyroidea
Inferior) arises from the upper  face of the subclavian,  and
goes  to the thyroid gland.   It ascends at first on the inter-
nal margin of the scalenus medius muscle, and then turns
suddenly inwards between the vertebrae and the  great ves-
sels of the neck.
  In this course  several unimportant twigs are  sent from   f
it to the contiguous  parts.   Near its root it detaches  the
Anterior or the Ascending Cervical Artery, which going up
the neck is spent upon  the  heads of the muscles arising
from the transverse processes,  as the scaleni, the longus
colli, and so on.   The inferior thyroidal  then  gets to the
thyroid gland, and is very minutely distributed to  it, anas-
tomosing with the other arteries which supply the same
organ.

   3.  The Superior Intercostal Artery (Arteria Intercosta 
            SUBCLAVIAN AND ITS BRANCHES.          205

lis Superior) arising from  the under surface of the subcla-
vian opposite the inferior thyroid, descends across the neck
of the first rib,  and divides into two branches, which sup-
ply the two upper intercostal spaces: each of them also
sends backwards near the  vertebrae a small trunk  to the
muscles of the back.

  4.  The Internal Mammary Artery (Arteria Mammaria
Interna.  Thoracica)  descends at first along the internal
margin of the scalenus anticus; having then got fairly into
the cavity of the thorax, it continues to descend across the
posterior  face  of the  costal cartilages, parallel with, and
about nine  lines from, the outer edge of  the sternum, be-
tween the triangularis sterni and the intercostal muscles.
   In this course, besides some distinct twigs to the anterior
mediastinum, it sends a branch which accompanying the
phrenic nerve  between the pleura and  the  pericardium,
reaches finally the diaphragm, and is spent upon it.  At
each intercostal space which it crosses, the internal mam-
 mary sends off one branch, which is  spent upon the fore
 part of the intercostal muscles,  and anastomoses with the
 corresponding intercostal  artery; other branches also leave
 it at each space, which getting forwards near the sternum,
 are distributed upon the pectoralis major,  and upon the con-
 tiguous muscles.   The last of these branches,  according to
 M. H. Cloquet, goes transversely over the ensiform carti-
 tilage, and  having anastomosed with its fellow descends be-
 tween the peritoneum and the linea alba to the suspensory
 ligament of the liver.
   On a line generally with the  anterior  extremity of the
 fifth rib,  the  internal mammary divides into two principal
 branches; the most exterior of which, descending along the
 cartilaginous margin of the thorax, is distributed in small
 twigs to the origin there of the diaphragm and of the trans-
 verse muscle of the abdomen.  The internal branch reaches
 the posterior face of the  rectus  abdominis muscle and is
 dispersed upon it; some of its branches reach as low as the
 umbilicus to anastomose there with the epigastric artery. 
206
CIRCULATORY SYSTEM-
   5. The Posterior Cervical Artery (Arteria  Cervicalis
 Posterior, Transversa) is of a very unsettled  origin, but
 comes most frequently either from the subclavian itself, or
 from the inferior thyroid. It is but small in some subjects,
 owing to its place being supplied by branches from the ad-
 joining arteries.
   It crosses horizontally the  root of the neck on the outer
 face of the scaleni muscles above the subclavian artery.  It
 gets under the anterior margin  of  the trapezius,  and is
 there divided into two  principal branches; the ascending
 one is spent upon the trapezius and the levator scapulae; the
 other descends along the base of the scapula, and is spent
 in  ramifications  upon  the rhomboideus and  the  serratus
 magnus muscles.  Several branches of minor size and im-
 portance are sent off from the posterior  cervical artery to
 the muscles on the back of the neck and thorax.

   The  Subclavian  artery having  sent  off the  preceding
 branches, then escapes from the thorax between the scaleni
 muscles, and gets to the arm-pit between the first rib and
 the subclavius muscle.   The  trunk of  it is then continued
 downwards through  the axilla, and at the inner side of  the
 arm to the elbow joint.
   From the scaleni muscles to the elbow its  relative posi-
 tion is as follows: When it first appears between the scale-
 ni, it is bounded  above and  behind by the collected fasci-
 culi of  the axillary plexus of nerves.   In front it  is sepa-
 rated from the subclavian vein  by the  insertion  of the
 scalenus anticus.   It is placed at the bottom of the  depres-
 sion between the  sterno mastoideus and the trapezius, being
 covered by the skin, the platysma myoides, and some loose
 cellular  substance below the latter.  It then descends be-
tween the first rib and the subclavius; escaping from below
 the latter, it is covered in front by the outer margin  of the
pectoralis  major until it reaches the lower part of  the ax-
 illa: and in this course it has the following relation to other
parts; it passes under the shoulder joint, then under the in-
sertion of the pectoralis minor, then along the  internal face 
             SUBCLAVIAN AND ITS BRANCHES.          207

of the coraco brachialis muscle; it has the axillary vein in
front of it and the axillary nerves plaited around it  as far
down as the coracoid process, when they begin to disperse.
This artery in emerging from the axilla is placed upon the „
anterior face  of the insertion of the latissimus dorsi; it then
runs out the  length of the coraco brachialis,  and is  after-
wards  conducted along the inner margin of the biceps flexor
cubiti and its tendinous termination; it lies upon the ante-
terior face of the brachialis  internus; and goes beneath the
aponeurosis at the bend of the  arm, coming from the ten-
don  of the biceps.  In  the arm it is concealed only by the
integuments and fascia,  and  is bordered  internally by the
brachial vein and the median nerve.

   This great trunk of the upper extremity loses the name
of subclavian to  be called Axillary Artery, (Art. Axilla-
ris,) from the subclavian muscle to the lower margin of the
arm-pit; and from the latter place to the  elbow joint, it is
named Brachial Artery, (Art. Brachialis.)  It sends off
many interesting branches to the thorax, to the shoulder,
and  to the arm;  and finally terminates a  little below or at
the elbow joint by bifurcating.

        Of the Branches of the Axillary Artery.

   1. The Superior Scapular Artery (Art. Dorsalis Supe-
rior Scapulas)  varies considerably in  its origin.   Some-
times it is a branch of the subclavian, sometimes of the in-
ferior  thyroid, and it frequently comes from the upper part
of the axillary, so that it cannot be referred, with strict pro-
priety, to any determined  origin.  When it comes from
the  axillary,  it is very tortuous and has to ascend to its des-
tination, which  removes it  entirely from  any interference
with the  course of the  subclavian  over the first rib, and
over the upper head of the  serratus magnus muscle.   But
 in the other  cases,  it  goes transversely backwards and out-
 wards, somewhat below the posterior  cervical, and  along
 the posterior inferior margin of the clavicle, being covered
 by the sterno-mastoideus, the platysma  myoides, and the 
208
CIRCULATORY SYSTEM.
trapezius; consequently it is just in the way of the incisions
which are made for reaching the subclavian  artery, from
above the clavicle.
  It reaches the superior costa of the scapula  near the root
of the coracoid process, and passing  through the notch
there, is  distributed, by one large branch, upon the supra-
spinatus  muscle; and by another, which goes across the an-
terior margin of the spine of the scapula, to the infra-spi-
natus muscle.   In its course,  it sends off several small ra-
mifications to contiguous parts.

  2.  The External Mammary Arteries (Art.  Mammariae
seu  Thoracicae Externas) arise from  the axillary, between
the  subclavius  and  the  pectoralis  minor muscles.  They
are four  principal trunks,  which go  uniformly to certain
parts, but vary considerably in their origin; for sometimes
the latter is distinct in the case of each artery, but frequent-
ly otherwise.   Their distribution is as follows:
  a.  The Thoracica Superior is distributed to the upper
part of the  pectoralis  major muscle, and  to the pectoralis
minor.   Some of  its branches reach the mamma in the fe-
male, and anastomose with the internal  mammary and with
the intercostals.
  b.  The Thoracica Longa descends along the posterior
face of the  pectoralis  major,  between  it and  the serratus
magnus.   It gives many branches to the lower part of the
pectoralis major, to the integuments, and in  the female to
the mamma; anastomosing likewise with the internal mam-
mary and with the intercostals.
  c.  The Thoracica Acromialis, immediately after its ori-
gin, makes for the fissure between the deltoid and the great
pectoral  muscle, and divides there  into an ascending and a
descending  branch.  The former reaches the clavicle, and
is partly distributed superficially along it, partly to the con-
tiguous muscles and to  the shoulder articulation.   The other
branch follows the cephalic vein along the interstice between
the  deltoides and pectoralis major, and is finally distributed
to these  muscles and to the integuments. 
AXILLARY ARTERY.
209
  d. The Thoracica Axillaris is irregular, both in regard to
the number of its branches and to their origin.   Instead of
a distinct origin by one or more trunks  from the axillary
artery, the branches belonging to the name of thoracica ax-
illaris, are sometimes derived from the other thoracic arte-
ries.  They are generally distributed only  to the fat and
the lymphatic glands in the  axilla.  They occasionally ex-
ist primitively as a large trunk, which runs on the scapular
face of the serratus magnus the whole length of the scapula,
and is distributed to the adjacent muscles,  and  to  the fat
and glands of the axilla.

   3.  The  Scapular Artery (Arteria Scapularis commu-
nis, Subscapularis) arises from the axillary below the shoul-
der joint, at or near the anterior margin of the subscapula-
ris muscle.   Giving off some inconsiderable branches to the
lymphatic glands of the arm-pit, it descends along the an-
terior margin of the subscapularis, and is distributed to it,
to the latissimus dorsi, and  to the teres major  and minor
muscles.
   A little below the neck of the scapula, it detaches a large
trunk, the Dorsalis Inferior Scapulae, which, winding around
the inferior costa of the bone over the  anterior  margin of
the subscapularis and the teres minor, reaches the fossa in-
fra-spinata.   This trunk then divides into  two branches:
one of which is distributed  superficially between the apo-
neurosis and the infra-spinatus, and the other more  deeply
near the dorsum of the bone: one of the ramuscles of the
latter ascends beneath the neck of the acromion to anasto-
mose with the Dorsalis Superior Scapulae.

   4.  The Anterior Circumflex Artery (Art. Circumflexa
Anterior, Articularis Anterior) is about the size of a crow
quill, and arises from the axillary just above the tendon of
the teres major and of the  latissimus  dorsi.  It adheres
closely to, and surrounds the front of the neck of  the os
humeri,  passing between it,  the  coraco-brachialis, and the
short head of the biceps.    It then  divides into several   ,
   Vol. II—27 
no
CIRCULATORY SYSTEM.
branches, some of which go to the deltoides and anastomose
there with the posterior circumflex; others go  immediate-
ly to the articulation, and either terminate on it or ascend
to the muscles  on the  dorsum of the scapula, where  they
anastomose with the scapular arteries.

   The Posterior Circumflex  Artery (Art.  Circumflexa
Posterior) is much larger than the last, and arises from the
axillary somewhat below it.  It surrounds the posterior face
of the neck of  the  os  humeri, passing between it and the
long head of the triceps muscle, below the insertion of the
teres minor.  Many of its ramifications go to the capsular
ligament of the articulation and to the muscles adhering to
it.   But this artery is  principally intended for  the deltoid
muscle, to the internal  face of which the most of its branches
go.   It anastomoses with the anterior circumflex, and with
the scapular arteries.
   In some  cases, the posterior circumflex arises from the.
axillary below, instead of above the tendinous insertion of
the latissimus dorsi; when this happens, it commonly gives
off the arteria  profunda major of the arm, and afterwards
ascends on the posterior face of the tendon to its appropriate
destination.

        Of the  Branches of the Brachial Artery.

   1. The Profound Artery (Arteria Profunda Major Hu-
meri, Spiralis) arises  from the brachial, a little below the
tendinous insertion of the  latissimus dorsi; and  having
passsed downwards, for a short distance, it enters the inter-
stice between the first and the third head of the triceps mus-
cle, and winds spirally  downwards around the os humeri in
company with the radial nerve.   On the outer side of the
arm, it becomes superficial between the margins of the tri-
ceps and of the brachialis internus, and  then directs its
course between the  latter  and the supinator longus to the
external condyle.
   In this course, the artery sends  several branches to the
triceps muscle,  to which, indeed, it is principally destined. 
AXILLARY ARTERY.               211
Near the external condyle, it supplies the brachialis inter-
nus and the heads of the extensor muscles of the fore-arm,
and anastomoses with the recurrent branch of the radial ar-
tery.

   2.  The Small Profound Artery (Art. Profunda Minor)
comes from the brachial, two  or  three  inches below  the
profunda major, but  frequently it  is only a branch of  the
latter, and is generally much smaller.   It is distributed su-
perficially on the internal  face of  the triceps at its lower
part, and has its terminating branches reaching as far as the
internal condyle.

   3.  The Nutritious Artery (Art.  Nutritia) is the next in
order from the brachial; and arises from it near the medul-
lary foramen of the os humeri, through which it penetrates
and is distributed to the lining membrane of the  bone.  It
is not larger than a knitting needle.

   4.  The Anastomotic Artery  (Arteria Anastomotica)
arises from the brachial below the last, and is larger than it.
It lies upon the lower internal part of the brachialis internus
muscle, and crosses the ridge leading to the internal condyle
in order to reach the depression between  the latter and the
olecranon, where it anastomoses with the ulnar recurrent ar-
tery.

   The preceding is a common arrangement of the branches
proceeding from the brachial artery, yet deviations from it
are continually met with, in a deficiency or in a redundancy
of these collateral trunks, and in their mode of origin.   An
account of all the varieties which are observed here would
be almost endless, as every subject has  some peculiarity.
Several small arteries are also sent from the brachial to the
coraco-brachialis, the biceps, the brachialis internus, and to
the triceps muscles.  They for the most part are simply
muscular branches, which are too small and irregular to de-
serve  specifying.
  The division  of the brachial artery into the two trunks, 
212
CIRCULATORY SYSTEM.
the Radial and the Ulnar, will be found in a majority of sub-
jects in front of the brachialis internus muscle on a line with
the elbow joint, sometimes it occurs nearer  the root of the
coronoid process.  It is however by no means rare to see
this bifurcation much above the elbow.  Examples of it have
been witnessed at every point  between the latter and the
arm-pit;  in such cases the course of the radial artery down
the fore-arm is generally much  more superficial than usual,
as it is placed immediately below the skin.


                 Of the Radial Artery.

   The Radial Artery (Arteria Radialis) is smaller than the
ulnar,  and extends from  the elbow to the  hand.   In the
upper half of the  fore-arm it is placed at the bottom of the
fissure between the supinator radii longus and  the pronator
teres muscle.  Having crossed the insertion of the latter, it
runs in front of the radius, between the tendon of the supi-
nator and of the flexor  carpi radialis.  Below the styloid
process of the radius  it runs between the outer end of the
carpus and the extensor muscles of the thumb; it then pene-
trates to  the palm of the hand between the root of the meta-
carpal bone of the thumb and of the fore-finger, above the
abductor indicis muscle.
   The following branches are  sent from the  Radial Ar-
tery.

   1. The Recurrens Radialis arises at the neck of the ra-
dius.   It winds externally around the joint between the ex-
ternal  condyle and the muscles coming from it, and an-
astomoses with the spiralis  of  the humeral artery, being
distributed in many collateral branches, to the joint and to
the contiguous muscles.

   2. Several small and irregular  muscular  branches  arise
from the radial artery, in its progress to the wrist; they have
no appropriated names. 
ULNAR ARTERY.
213
  3. The Superficial Volae arises from the radial about the
inferior margin of the pronator quadratus muscle.  It passes
superficially over the process of the trapezium to the mus-
cles of the ball of the thumb, and one of its  terminating
branches joins the arcus sublimis.   Sometimes the  superfi-
cialis volae is the principal branch of the radial.

  4. The Dorsalis  Carpi arises from the radial at the car-
pus, runs across  the back of the latter below the extensor
tendons, and detaches the posterior interrosseous arteries of
the back of the hand.  They anastomose with branches from
the ulnar and interosseous arteries of the fore-arm.

   5.  The Magna Pollicis, a terminating branch of the ra-
dial, comes from it in the palm of the hand just at the root
of the metacarpal bone of the thumb.   It runs beneath the
abductor indicis, and at the head of the metacarpal bone di-
vides  into two branches which run along the sides of  the
thumb to its extremity, where they anastomose and termi-
nate.

   6. The Radialis  Indicis, arising at the same place with
the latter, runs along the metacarpal bone of the fore-finger,
and along the radial side of the same finger to its extremity.

   7.  The Palmaris Profunda is the third terminating; branch
of the radial artery.  It arises near the same place with the
two last, crosses the  hand between the metacarpal bones
and the flexor tendons; thus forming the Arcus Profundus,
from which branches proceed to the interossei  muscles, and
which ends on the ulnar side of the palm of the hand by a
branch to the Arcus Superficialis.


                  Of the Ulnar Artery.

   The Ulnar Artery (Arteria Ulnaris) one of the  forks of
 the brachial at the elbow, passes more in a line with it than
 the radial artery does. It goes, immediately after its origin, 
214
CIRCULATORY SYSTEM.
under  several of the muscles of the internal condyle, to
wit: the pronator teres, flexor radialis, flexor sublimis, and
palmaris longus, and between the flexor sublimis and pro-
fundus digitorum, being deeply seated; getting from beneath
the flexor sublimis, it afterwards runs parallel with the ulna
or nearly so, lying on  the flexor profundus between the
flexor ulnaris and  the ulnar margin of the flexor sublimis,
and concealed two-thirds of the way down the fore-arm by
the overlapping of these muscles.  At the  thin part of the
fore-arm, commonly called the wrist, it  is superficial, and
may be felt pulsating in the living body at the radial margin
of the tendon of the flexor ulnaris.
   The ulnar artery, at the carpus,  takes  a very different
course from the radial, for it passes over the anterior annu-
lar ligament of  the  carpus just at the radial side of the os
pisiforme, to which it is held by a small ligamentous noose;
it then proceeds to the palm of the hand.  Between the apo-
neurosis  palmaris and the flexor tendons it forms that curve
from the ulnar to the radial side of the hand called the Arcus
Sublimis. This  curve commonly begins a little beyond the
anterior margin of the annular ligament, and presenting its
convexity forwards, terminates about the middle of the ball
of the thumb at its inner margin.
   The branches sent from the ulnar artery are as follow:

   1. The Recurrens Ulnaris arises from the ulnar about the
lower  part of the tubercle of the radius, and winding up-
wards is  distributed in  small branches to the muscles of the
internal  condyle.  One of its ramuscles goes between the
internal condyle and the  olecranon  process to anastomose
with the  arteria anastomotica of the humeral.

   2. The Interossea arises from  the ulnar just below the
other.  It is a large trunk,  and proceeds but a little distance
when it divides into two principal branches, called anterior
and posterior interosseal arteries.
   a. The Interossea Anterior is much the larger; it runs in
contact with the interosseous ligament to the upper margin 
ULNAR ARTERY.                215
of the pronator quadratus, giving off branches to the deep-
seated muscles of the fore-arm in its course. Under the pro-
nator it perforates the interosseous ligament and distributes
branches to the back of the carpus and of the hand, which
anastomose with branches of the radial and posterior inter-
osseal.
   b. The Interossea Posterior is sometimes a separate trunk,
arising from the ulnar just above the former.  In either case
it soon  perforates the interosseous ligament to get to the
back of the fore-arm.  Here it sends backwards  a Recurrent
Branch to  the back of the elbow, which  anastomoses with
the recurrens ulnaris and radialis.   It then proceeds down-
wards,  being deeply seated and distributed to the different
muscles on the back of the fore-arm.   Some of its branches
reach the wrist, and anastomose with the carpal arteries.

   3. The ulnar artery, in its descent on the fore-arm, sends
off many small and irregular muscular branches called by
Professor  Chaussier,  Cubito-musculaires: they do not  re-
quire description.

   4. The  Dorsalis Manus leaves the ulnar at the lower end
of the  fore-arm, and passes under the tendon of the flexor
ulnaris to  the back of the hand.   It there meets ramuscles
of the  radial  and interosseous, and conjointly they supply
with very small branches the back of the wrist, of the me-
tacarpus and of the fingers.

   5. As the Arcus Sublimis is about beginning,  the ulnar
artery sends superficial  but small branches to  the integu-
ments of the palm:  and a little  further on, a  considerable
branch, which dives into the bottom of the palm, through
the muscles of the little finger,  and joins the  ulnar extre-
 mity of the  arcus  profundus; this is  the Cubitalis Manus
 Profunda of Haller.

   6. The  Arcus Sublimis then sends a branch  to the ulnar
 side of the little finger.  Afterwards in succession three di-
 gital branches are sent off, which, arriving at the interstices 
216
CIRCULATORY SYSTEM.
between the heads of the metacarpal bones, each divides
into two branches to supply the sides of the fingers which
are opposite to each other; one branch is called Digito-radial,
the other Digito-ulnar, according to the side of the finger on
which the artery may be placed.
   The Digital Arteries, before they divide, receive each a
small branch from the arcus profundus.  The digito-radial,
and the digito-ulnar arteries, pass along the sides  of the
fingers in front to their extremities; at the joints and extre-
mities, anastomoses between the arteries of the two sides of
the same finger frequently occur.
   The arcus sublimis terminates  on the radial side of the
palm by a branch which joins the inner branch of the Ar-
teria Magna Pollicis of the Radial.
   The most frequent arrangement of the arteries of the hand
is  what has been just described; anatomists are,  however,
not all agreed on this point.  It would probably be  more just
to say, judging from our collection in the University,  that
this occurs more than any other single arrangement.    The
varieties, in fact,  are so great, that before a hand is opened,
it is not possible to know in what  manner its arteries  will
be distributed.  Sometimes the Radial Artery furnishes one
half of the arcus sublimis, and the Ulnar the other half.  On
other occasions, the interosseous  artery is continued as a
large trunk over  the ligament of the wrist, and across the
root of the thumb, to join the arcus sublimis.


   SECT. IV.--BRANCHES OF THE DESCENDING THORACIC
                        AORTA.

  The Aorta, in its course from the lower part of its curva-
ture to the crura of the Diaphragm, gives off several branches
to  the viscera and to the parietes of the thorax.

  The Bronchial Arteries, (Arteriae Bronchiales) are the
nutritious vessels of the lungs. There is commonly one for
each lung, but sometimes two or more.  The right arises
frequently from the superior intercostal artery, instead of 
          BRANCHES OF THE THORACIC AORTA.       217

from the aorta, while the left comes from the latter; occa-
sionally they have a common root.
  On either side they follow the course of the bronchia into
the substance of the lung; and are distributed along with it,
by ramifications which become successively finer and finer,
and anastomose with  the  pulmonary artery; after the man-
ner mentioned in the description of the lungs. Before they
enter the latter they send some  small ramifications to the
posterior mediastinum, to the pericardium, and to the black
bronchial glands.

  The  (Esophageal  Arteries (Arteriae  (Esophageae) are
generally five  or  six small twigs which come successively
from the descending thoracic aorta.  They ramify minutely
in the  substance of the oesophagus, communicating freely
with each other; the lowest of them also anastomoses around
the cardia with the superior coronary artery of the stomach.

  The posterior Arteries of the Mediastinum, (Arteriae Me-
diastinales Posteriores,) are numerous and small; they
come from  the anterior face of the aorta, as well as from the
branches last mentioned; and are spent upon the posterior
mediastinum, and upon its contents.

   The intercostal Arteries (Arteriae Intercostales inferiores
aorticas) of the aorta supply the ten lower intercostal spaces
on each side,  as the two upper ones are supplied by the sub-
clavian artery.   There is commonly an intercostal artery
arising  distinctly from the aorta for each space, but some-
times two of them arise from a common trunk.  Those for
the right side having to cross the spine behind the oesopha-
gus and the vena azygos, are, of course, longer than such as
belong  to the left.   The  upper ones on either side have to
ascend, in order to reach  their destination.
  Each artery joins the rib near its tubercle, and goes along
the groove in its lower margin, between the external and the
internal intercostal muscles, for two-thirds of the length of
the rib.  It then abandons the groove, and divides  into seve-
  Vol. 11 — 2S 
218
CIRCULATORY SYSTEM.
ral branches, which go to the intercostal muscles and conti-
guous parts, anastomosing in front with the internal mam-
mary artery.
  As each  intercostal artery passes the head of the rib, it
sends a branch backwards, (ramus dorsalis,)  between the
transverse processes  of the  adjoining vertebrae, which pe-
netrates to  the posterior face of  the trunk, and is distri-
buted to  the muscles and skin  on the side of the spine.   A
ramification from this branch enters the intervertebral fora-
men, and is spent upon the  medulla spinalis and its mem-
branes.
  Each intercostal artery also gives off, about the middle of
the rib, a branch, (ramus costalis inferior,) much smaller
than the trunk.   This branch advances along the upper mar-
gin of the rib below, and gives ramifications to its periosteum
and to  the adjacent intercostal muscles.
  The  last intercostal artery is remarkable for its size.   Its
origin is concealed by the small muscle of the diaphragm, to
which  it gives some ramifications; it then passes, at the
under margin of the rib, behind the upper end of the quadra-
tus lumborum muscle, where it divides into three branches;
one of  which goes transversely to the broad muscles of the
abdomen; while the other two descend between the oblique
and transverse muscles towards the crest of the ilium, where
they anastomose with the lumbar arteries, and with the cir-
cumflexa ilii.
 SECT. V.--OF THE BRANCHES OF THE ABDOMINAL AORTA.

  The Phrenic Arteries (Arteriae Phrenicae) are two in
number, one for the right and the other for the left side of the
diaphragm.  They arise singly, but sometimes by a common
trunk from the front of the aorta, immediately on the latter
showing itself in the abdomen, between the crura  of the dia-
phragm; consequently just below the crossing of the muscular
fibres, which takes place between the foramen for the aorta
and that for the oesophagus. 
          BRANCHES OF THE ABDOMINAL AORTA.      219

  The phrenic arteries ascend along the lesser muscle of the
diaphragm, and  give some ramifications to it  and to the
capsulae renales.  They then divide each into two princi-
pal trunks, which are distributed over the diaphragm, prin-
cipally on its  concave surface.  Some small ramifications
from them go  to the liver and to the lower part of the oeso-
phagus.
  The two pherenic arteries anastomose with  each other:
also, with the superior phrenics, coming from the internal
mammary;  and with the intercostals.  Sometimes one or
both of them comes from the coeliac artery, or its branches.

   The Coeliac Artery (Arteria Ceeliaca) is the  next branch
of the  abdominal aorta, and arises immediately below the
phrenic, between the pillars of the diaphragm, opposite the
junction of the last dorsal with the first lumbar vertebra.
It is a very large trunk, and goes  off at right angles, being
placed  between the left lobe of the liver and the superior
margin of the pancreas.  When it is only half an inch long
it is split into three trunks, the Gastric, the Hepatic, and the
Splenic; this division is the Tripus Halleri.

   The Gastric Artery (Arteria Gastrica, Coronaria  Ven-
 triculi) is the smallest of the three trunks, and frequently
arises from one of the others.   It advances forwards and to-
wards the left, in order to reach the small curvature of the
stomach, the course of which it pursues to the .pylorus,  be-
tween the two laminae of the little omentum.  It gives off
the following branches.
   a.  Ramifications to the oesophagus, some of which  as-
cend along it  into  the posterior  mediastinum, and anasto-
mose there with the similar branches coming from the aorta;
others go transversely, so as to surround the cardia, reach
the greater end of  the stomach, and  anastomose with the
vasa brevia.
   b.  The ramifications to the stomach are abundant, but of
 an indeterminate number, and arising along  its lesser cur-
 vature, are distributed  in winding branches to  the anterior 
220              CIRCULATORY SYSTEM.
and the posterior surfaces of this viscus, between its mem-
branes.
  c.  Not unfrequently the artery which supplies  the left
lobe  of  the liver is a branch from the gastric, in which case
the latter is much larger than usual.

  2.  The Hepatic Artery (Arteria Hepatica) is generally
considerably larger than  the gastric,  and inclines towards
the right side, in  order to reach the liver, which it does
through the capsule of Glisson.   It sends off the following
branches.
  a. The Right Gastric or Gastro-Epiploic Artery (Arte-
ria Gastrica Dextra) comes from it near the pylorus, and
descending  between the  duodenum and  pancreas, reaches
the greater curvature of the stomach,  to the right half of
wb' *h, and to the corresponding part of the great omentum,
it    distributed.   In the early part of its course, the right
.•itiic  detaches  some  small ramifications to the pylorus
    /'/rise pyloricas;) also, to the duodenum and to the pan-
    ;  art. pancreatico duodenales.)  The latter commu-
       by very free anastomoses, with the superior mesen-
teric artery.
   rL,"-?.' having sent off this branch, the hepatic artery  ad-
vances to the transverse fissure of the liver, in front of and
   '":.'.   left of the vena portarum.   It  then divides into a
 ■ ■ • : and a  left branch.   The  former sends off a ramifica-
     to the gall bladder, (art. Cystica,) which reaches first
ii 5 neck and is distributed, by many arterioles, upon  the
    3tes of this reservoir; the right branch then penetrates
  :• -  ly  into  the  transverse fissure, and is  distributed, by
    y ramifications, throughout the right lobe of the  liver.
The left branch of the  hepatic artery is distributed, in  the
same manner, throughout the left lobe of the liver.

   3. The Splenic Artery (Arteria Splenica) is larger in
the adult than either of the other two branches of the coeliac,
?rri goes to  the  spleen  along  the  superior margin of  the
pancreas, performing, in  this course, several considerable
flexuosities.   It gives off the following branches: 
          BRANCHES OF THE ABDOMINAL AORTA.     221

  a. The Pancreatic Arteries (Art. Pancreaticas Mediae et
Sinistrae) come  successively from its inferior margin, as it
goes along the pancreas.   Their number and size are varia-
ble, but commonly they are not bigger than a knitting nee-
dle;  they penetrate perpendicularly into the  pancreas, and
then subdivide  minutely  in furnishing its structure:
  b. The left Gastric Artery (Art.  Gastrica Sinistra,
Gastro-epiploica Sinistra) comes from the left extremity of
the splenic, and  is about the same size with the right gastric
artery,  but sometimes  larger.   It attaches itself to the left
extremity of the stomach, and goes along the left half of its
greater curvature, terminating by an anastomosis with  the
right gastric artery.   In  this  course, it detaches  ramifica-
tions to the front and to the back of the stomach, and to the
omentum majus:
  c. The Short Vessels (Vasa Brevia, Art. Gastricx Bre-
ves) come from the splenic, immediately before it enters
the  spleen, and after  it has subdivided for  that  purpose.
They are five  or six in number, and are distributed upon the
greater extremity of the  stomach, between the cardia and
the left  gastric artery.   The  anastomoses between the se-
veral arteries  of the stomach are so free, that a fine injec-
tion pushed into  one, readily finds  its  way  into all  the
others.
  The  splenic artery,  when it gets to the left end of  the
pancreas, is divided into  a cluster of branches, and in that
condition enters the fissure of the spleen, throughout the in-
terior of which  it is divided into an infinitude of  ramifica-
tions.

  The Superior Mesenteric Artery (Arteria Mesenterica
Superior) arises from  the aorta, while the latter is still en-
gaged,  between the crura of  the  diaphragm.  It  is about
the same size as the coeliac, and comes off half an inch be-
low it.   It is  distributed  to all the small intestine and to
the right side  of the large one after  the following  manner:
it first passes behind the pancreas, and then in front of the
duodenum, to reach the root of the mesentery, between the 
222              CIRCULATORY SYSTEM.
two laminae of which it divides and subdivides into several
series of arches, one after another; they become successive-
ly smaller and more numerous till they reach the margin
of the intestine, where they cease by sending a great many
small parallel branches.
   The trunk of the superior mesenteric artery, in descend-
ing between the laminae of the mesentery, describes a con-
siderable curvature, the convexity of which is to  the left
side and downwards, while its concavity is in a contrary
direction.   It is  from  the convexity of this  trunk, that
from fifteen to twenty large branches are sent off succes-
sively to form the roots of the first row of arterial  arches.
These branches are shorter, and generally somewhat smaller,
the lower down they arise; and their  origins very closely
succeed each other.
   Besides the preceding branches, the superior mesenteric
artery sends off the following:
   Near its root several small ramifications arise, which go
to the duodenum and to the pancreas, and anastomose there
with other arteries supplying the  same organs:
   From about the middle of the  concavity of the superior
mesenteric artery, arise the three Colic arteries called Ileo-
colica,  Colica Dextra, and Colica  Media:  the first supplies
a cluster of branches to the lower part of the ileum and to
the head of the colon, anastomosing on the left with the
last of  the small intestinal  arteries and on the right with
the colica dextra: the Colica  Dextra is smaller than either
of the other two branches,  and going between  the  laminae
of the mesocolon, supplies the ascending portion of the colon
by dividing  into two principal branches, one of which anas-
tomoses with the ileo-colic artery, and the other with the
colica media:  the  Colica Media,  situated between the la-
minae of the transverse  mesocolon, and arising higher up
than the colica dextra, advances forwards and divides into
two principal  trunks;  one of which supplies  that part of
the colon in the right hypochondriac region, and the other
the remainder of its transverse portion, forming an anasto-
mosis with the colica superior of the inferior mesenteric ar- 
BRANCHES OF THE ABDOMINAL AORTA.      223
tery.  The arteries which supply the colon differ from those
supplying the small intestines, in forming but one row of
arches;  which, in fact, are produced by the anastomoses
spoken  of,  and have, therefore, extremely large meshes.
From the convexity of these arches, many parallel branches
run out to supply the colon, and are very minutely distri-
buted to it.

  The Capsular Arteries, the Emulgents, and the Sperma-
tics, arise from the aorta, between the superior and  the in-
ferior mesenteries.  But  they will  be  described after the
inferior  mesenteric, so as  to  keep together the account of
the arteries of the intestines.

   The Inferior  Mesenteric Artery (Art. Mesenterica In-
ferior)  generally arises about  one inch  above  the division
of the  aorta  into the  two  primitive iliacs, and is much
smaller than the  superior Mesenteric.  It inclines down-
wards to the left side, and gets between the laminae of the
mesocolon; it then divides into three branches, called the
Left Colic Arteries, from  their distribution to the left side
of the colon.   From their relative  situation to each other
they are distinguished  into the  Superior,  the Middle, and
the Inferior;  sometimes however there are but two of these
trunks.

   The  Superior  Colic (Art.  Colica Sinistra  Superior)
goes horizontally towards the colon in  the left lumbar re-
gion; having got near the intestine it divides into two
branches, one of which ascends to  the  transverse colon to
form the anastomosis with the Colica Media of the upper
mesenteric, while the other descends to unite with the colica
media sinistra.  The middle Colic Artery (Art. Colica Si-
nistra Media) is sometimes a  branch of the superior, and
is occasionally wanting; it goes towards the upper  part of
the sigmoid flexure of the colon, and then bifurcates; one
branch ascends to form by anastomosis an arch with  the su-
perior colic, while the other branch descends to join the 
224
CIRCULATORY SYSTEM.
lower colic artery.   The Inferior Colic Artery (Art. Coli-
ca Sinistra Inferior) goes towards the middle of the sig-
moid flexure of the colon,  and there like the preceding di-
vides into two branches; one  anastomoses with the artery
above, while the other joins with the arteries which go to
the rectum from the inferior mesenteric.
  The Superior Haemorrhoidal Artery (Art. Hasmorrhoi-
dea Superior, Interna) is  the lowest and the last branch of
the inferior mesenteric.   It descends between the laminae of
the  mesorectum,  and is  divided  into two symmetrical
trunks, which radiate by dividing and subdividing on the
side of the rectum, and  are dispersed in very fine and nu-
merous branches throughout its substance; and anastomose
with  the middle and the  inferior  haemorrhoidal arteries,
also, with the lateral sacral.

  The Capsular Arteries  (Art. Capsulares)  arise frequent-
ly from the aorta just below the superior  mesenteric; but
quite as often, if not more so,  from  the emulgents.  They
are not larger than a crow's quill,  and vary from  one  to
three on either side, generally, however, not exceeding
one; when they do, they are proportionably small.  Pass-
ing horizontally outwards they divide  into  several small
ramifications, which  terminate  in the  capsulae renales.
Some of their  branches go  to the lesser muscle of the dia-
phragm.

  The Emulgent Arteries (Art. Emulgentes Renales) are
two in number, one for each kidney, but sometimes more.
They are large and short, arise from the side of  the aorta
immediately below the superior  mesenteric, and  pass out-
wardly in a horizontal direction.  The right one  is longer
than the left, somewhat lower down, and passes behind the
ascending cava.   They are  both,  in their course  from the
aorta to the kidney, covered in front by the emulgent vein,
and have to pass through  a  mass of adipose matter.
  The emulgent sends off some fine ramifications to the adi-
pose matter, which surrounds  it,  and before it reaches the
fissure of the kidney divides into three or four branches, 
         BRANCHES OF THE ABDOMINAL AORTA.      225

preparatory to its introduction into this gland; upon the
structure of which it is ultimately distributed by very fine
branches.

  The  Spermatic Arteries (Arteriae Spermuticx, Semi-
nales) arise from the aorta somewhat below the emulgents,
but in some cases from the  latter  themselves.  They are
two in number,  one on each  side, and are about the size of
a crow quill in the male subject, but smaller in the female.
One comes off  generally higher  up than the other;  they
then descend  on the sides of the vertebral column before
the psoae muscles, and cross in front of the ureters, being in
all this course behind the peritoneum.  They are tortuous,
and shortly after their  origin begin to  adhere to the  sper-
matic veins, which adhesion is continued to the testicle.
   The branches that the spermatic artery sends off in the
abdomen  are  inconsiderable, consisting in very fine twigs
to the adjacent adipose matter, to the lymphatic glands, to
the ureter, and to the peritoneum.  In  the male subject
it passes with the vas deferens through the  abdominal ca-
nal, and reaching the  testicle divides into branches which
supply the body of this gland and the epididymis.  In de-
scending from the  external  ring to the testis, some small
ramifications,  to the adjacent parts  leave it.   In the female
the spermatic artery does not leave the cavity of the abdo-
men, but descending into the pelvis, gets between the la-
minae of the broad ligament to the  ovarium, and is spent
principally upon the latter.   Some of its branches go to
the Fallopian  Tube, to the Round Ligament of the uterus,
and to the sides of the  latter, where they anastomose with
the uterine arteries.
   The Lumbar Arteries (Arteriic Lumbares) are common-
ly five in number oh cither side, but seldom less than three
or four, and in their course outwards correspond with the
intercostal arteries.  They are much larger than the latter.
They arise in  pairs, from the posterior external face of the
aorta, at a  point corresponding with the middle of the bo-
dies of the four upper lumbar vertebra;; and pass outwards
   Vol.- II.   -'9 
22tf
CIRCULATORY SYSTEM.
between the fasciculi of the psoas magnus muscle, to which,
to the quadratus lumbor.um, and the bodies of the vertebrae,
they  distribute  several branches.   Sometimes each pair
arises by a common trunk from the posterior face of the
aorta; as the latter terminates  at the fourth lumbar verte-
bra, the fifth lumbar artery is  a branch from the fourth in
most instances.  At the base of the transverse process each
artery divides into two  branches, a posterior or dorsal one,
and an anterior or  lumbar.
  The dorsal branch, which is smaller than the other, de-
taches a ramification though the intervertebral foramen to
the lower part of the medulla spinalis and to the cauda equi-
na: it then gets to the back where it is spent upon the mus-
cles near the spine.  The anterior lumbar branch advances
between  the broad muscles of the abdomen, to which it is
distributed; and runs forwards far enough to anastomose with
the epigastric artery.
  The first lumbar  artery is small,  and sometimes comes
from the last intercostal; it goes a little below the inferior
margin of the  last rib,  and then descends almost vertically
between  the peritoneum  and  the  transversus abdominis
muscle.   The  lower lumbar arteries anastomose with the
circumflexa ilii,  and with  the superficial branches of the
gluteal.

  The Middle Sacral  Artery (Arteria Sacra Media) is
generally not so large as a lumbar; it arises from the centre
of the bifurcation of the aorta into the two primitive iliacs,
or else a  line or two above it, behind. It descends, in front
of the middle line  of the fifth lumbar vertebra and of the
sacrum, to the coccyx, adhering to the  surface  of these
bones and performing some flexuosities.
  It sometimes happens that the last pair of lumbar arteries
comes from it, or at least one,  according to Meckel, more
commonly the left, in which case the sacral is of unusual size.
The sacral afterwards sends off, to the right and left, a pair of
branches for each pair of sacral foramina.  They run across
the sacrum, s.end branches to it, anastomose with  the late- 
       INTERNAL ILIAC ARTERY AND ITS BRANCHES.   227

ral sacral arteries, and then penetrate  to the cauda equina.
The middle sacral artery is lost at the inferior end of the
coccyx, in the fat and cellular tissue of the part.


   SECT.  VI.--OF THE PRIMITIVE ILIAC ARTERY AND ITS
                       BRANCHES.

   The Primitive Iliac Arteries,  (Art. Iliacas Primitivss,
communes,) one on each side, are as mentioned, the ter-
minating trunks  of the abdominal aorta.   They extend
from the lower part of the fourth lumbar vertebra to the
sacro-iliac junction or near it, where they divide into two
trunks, the Internal and the External Iliac.
   The primitive Iliac is bounded on  the  outer side by the
psoas magnus  muscle,  and behind by  the primitive iliac
vein; it  is crossed  at  its lower part by  the  ureter.   No
branches deserving of especial notice are sent from it before
it bifurcates; such as exist are very small,  and  go simply to
the  parts immediately  contiguous.    The   right artery
crosses in front of the root of the left iliac vein.


   SECT.  VII.-->OF THE INTERNAL ILIAC ARTERY AND ITS
                       BRANCHES.

   The Internal  Iliac Artery (Art. Iliaca Interna, Hypogas-
trica) descends from the front upper part  of the sacro-iliac
junction, to  the  lower part of  the sacro-iliac junction.
In this descent, it is  bounded behind by the sacral plexus of
nerves, and gives off several arterial  trunks, but the man-
ner by which the last is accomplished is much varied in dif-
ferent subjects.   For the most part, it is an inch  or more
long before any important branches leave it; it is then fre-
quently divided into two principal trunks, an  anterior and
a posterior, from which proceed  the several branches that
supply the internal  and the external parts of the pelvis.
The rule of origin of the secondary trunks from these two
principal ones,  even when the latter exist, is not fixed, for 
228
CIRCULATORY SYSTEM.
sometimes they arise from one, sometimes from the other,
and then again from the trunk of the hypogastric itself.

  The Ilio-Lumbar Artery (Art. Ilio-lumbaris) is com-
monly the first branch of the hypogastric or of its posterior
trunk.  It ascends outwards and backwards behind the psoas
magnus muscle, and there divides into two branches, a su-
perior and an inferior.  The former continues to ascend be-
tween the psoas magnus and  the iliacus internus muscles,
to which, and to the quadratus lumborum,  it  distributes
branches; it also sends ramifications into the spinal cavity,
and anastomoses with the lower lumbar arteries; sometimes
it supplies the place of the last lumbar entirely.  The infe-
rior branch going outwardly is divided into  two orders of
ramifications which supply the iliacus internus muscle, on
its surface and more deeply, also the  os ilium by a ramus-
cle which penetrates the nutritious foramen of the latter.
The inferior branch anastomoses with  the circumflexa ilii
of the external iliac.

  The Lateral Sacral Arteries (Arteriae Sacrae Laterales)
arise next, either from the hypogastric or from its posterior
trunk, their number is commonly equal to that of the fora-
mina  on the side of the sacrum in front, though they come
from  only one or two roots.  They cross  the front of the
sacrum  and divide into branches, some of which anastomose
with the middle sacral artery, while others enter the fora-
mina  of the sacrum, to be spent  on  the lower part of the
cauda equina.

  The Obturator Artery (Arteria Obturatoria) comes com-
monly from the hypogastric or from one of its principal
trunks; in some cases it arises from  the epigastric or from
the external  iliac, near  Poupart's ligament.  In  the first
cases  it passes forwards parallel  with the  brim of the pel-
vis, and in  the latter cases it descends behind the superior
ramus of the pubes.   Whatever may be the condition of
its origin, it gets from the pelvis through |he upper part oi* 
      INTERNAL ILIAC ARTERY AND ITS BRANCHES.   229

the thyroid foramen over the superior  margin of the obtu-
rator internus muscle,  having previously sent off some in-
considerable ramifications to the periosteum and the conti-
guous muscles.
  It emerges from the  pelvis on the upper margin of the ob-
turator externus muscle, and then divides into two principal
trunks.   The posterior descends along the  external margin
of the obturator externus muscle, to which it  gives ramifi-
cations; it likewise sends some branches to  the heads of the
muscles coming from the tuber of the ischium and thereby
anastomoses  with the  sciatic artery;  other branches are
spent upon the hip joint, one of which gets into the cavity
of the latter through the notch at the lower part of the ace-
tabulum, and is spent upon the adipose  matter in its bottom.
The anterior branch goes to the heads of the adductor mus-
cles, to the pectineus,  to the obturator externus, and to the
integuments  of the upper internal part of the thigh.   Near
its origin this branch sends a ramification along the internal
margin  of the thyroid  foramen to anastomose with the pos-
terior branch, so that the foramen is  surrounded  by an ar-
terial circle.

   The Middle  Haemorrhoidal Artery (Art. Hasmorrhoidea
Media) varies  in its origin, being sometimes from  the hy-
pogastric  itself, and,  on other  occasions,  from one of its
branches, as  the gluteal, ischiatic, &c.    It descends on the
fore part of the rectum, opposite the  lower fundus of the
bladder in the male, and is distributed by branches to the
rectum, to  the vesiculae  seminales,  and  to  the prostate
gland.  In the  female  it dispenses branches to the vagina.
It is called middle from its position between the upper and
the lower haemorrhoidal arteries.
  In both sexes the branches  which it sends to other parts
besides the rectum, frequently arise from other arteries, and
in a manner which causes them to have distinct appellations
as vaginal, &c.

  The Vesical  Arteries (Arteriae Vesicates) consist in se- 
230              CIRCULATORY SYSTEM,
veral ramifications, coming from what was the umbilical ar-
tery of the foetus, but which, in the adult, with the excep-
tion of a short space near its origin, is converted  into a li-
gamentous chord.  These branches ramify upon the parietes
of the bladder;  one of them more voluminous  than  any
other, and called by M. Chaussier, vesico-prostatic, gains
the lower fundus of the bladder; sends branches to it, to
the prostate,  to the vesiculae seminales,  and to  the com-
mencement of the urethra.

  The Uterine Artery (Arteria Uterina) arises  from  the
hypogastric or one of its branches, near the vesicals, some-
times before, and on other occasions subsequent to them.
Being peculiar to the female sex, its size  varies according
to the individual, being in a state of pregnancy or not; in
the latter stages of  gestation  it is as large  as any other
branch of the hypogastric.
  It goes inwards towards the superior part of the vagina, to
which it gives some ramifications;  it then ascends between
the laminae of the broad  ligament, in a  tortuous manner
along the side of the uterus, and divides into many branches
which are distributed through the tissue of this organ.   It
anastomoses with the corresponding arteries of the other
side, and with the branches of the spermatic artery which
go to the Fallopian tube and to the ovarium.

  Besides the preceding, the  hypogastric artery sends off
two large branches, the Gluteal and the Ischiatic, which  ter-
minate it.  In many subjects they are the direct  continua-
tion of the two primitive trunks, into which  the  hypogas-
tric is frequently originally divided.

  The Gluteal Artery  (Arteria Glutea) shortly after its
origin, issues from the pelvis above the  pyriformis muscle,
at the upper part of the ischiatic foramen, where it adheres
closely to the edge of the bone.  When it first gets to the
dorsum of the ilium, it is covered by the gluteus  maximus
muscle, and lies at the  posterior margin of the  gluteus mi- 
      INTERNAL ILIAC ARTERY AND ITS BRANCHES.   231

nimus, precisely under a line drawn from the posterior  su-
perior spinous process to the top of the trochanter major.
It almost immediately afterwards divides into two principal
trunks.
  One of these trunks, the  more superficial, advances  be-
tween the gluteus medius and the maximus, and distributes
branches to them; also, to the posterior margin of the max-
imus, where  it comes from  the posterior sacro-sciatic liga-
ment.   The more  deeply seated trunk goes forwards  be-
tween the gluteus medius and minimus, and subdivides into
three orders of branches for their supply.  One set follows
the  superior margin of the  gluteus minimus  towards  the
anterior superior spinous process; another set passes nearer
the middle of the  gluteus minimus; and the third set still
lower down, upon the dorsum of the  ilium,  above  the ace-
tabulum, some of the ramifications going to the capsular li-
gament of the joint, where  they anastomose with branches
from the femoral artery.

  The Ischiatic Artery (Arteria Ischiadica) is somewhat
smaller than  the gluteal, but looks rather more like  the con-
tinuation of the hypogastric. It descends between  the rec-
tum and the  pyriformis muscle, and issues under the lower
margin of the latter, out of the  pelvis, being there placed
in front of the sciatic nerve.  It goes downwards on  the
back of the  thigh, between the trochanter major  and  the
tuberosity of the ischium, being at the internal edge of the
sciatic nerve, and on the posterior face of the small rotator
muscles of the thigh.  It sends off in the pelvis the Inter-
nal Pudic Artery, and  also some inconstant  branches, of
small size,  to the  viscera within the  pelvis; when it  has
emerged from the latter, it detaches  some  considerable
branches to the origin and to the inferior margin of the glu-
teus magnus muscle, and to the small rotator muscles. The
branch which may be considered as the continued trunk of
the ischiatic,  descending on the posterior face of the thigh
along with the sciatic nerve, under the hamstring muscles, 
232
CIRCULATORY SYSTEM.
 is lost in ramifications  to  them, and  by anastomoses with
 the perforating arteries.

   The Internal Pudic Artery, (Arteria Pudica Interna,)
 though a branch of the ischiatic, is only in a slight degree
 smaller.  It arises a little above the spinous process of the
 ischium, in the pelvis, in  front of the sciatic plexus, and
 getting from- the  pelvis between the anterior sacro-sciatic
 ligament and the inferior margin of the pyriformis muscle,
 it passes over the posterior face of the anterior sacro-sciatic
 ligament, at the spinous process of  the ischium.   It imme-
 diately afterwards returns into the cavity of the pelvis, be-
 tween the two sacro-sciatic ligaments,  at the place where
 the obturator internus  muscle winds over the ischium;  it
 then winds along the internal face of the latter bone and  of
 its ascending ramus, at the inferior  margin of the obturator
 internus muscle;  and continues on  the internal face of the
 ramus of the pubes, between the two laminae of the trian-
 gular ligament, above the crus of the penis to the symphy-
 sis of the pubes.
   In this course the Internal Pudic Artery detaches seve-
 ral important branches,  in the following order:
   a.  A ramification along  the inferior margin of the pyri-
 formis, to this muscle and to the parts on the posterior face
 of the neck of the os femoris, where  it anastomoses with
the other arteries of this region.
   b.  The  Lower Haemorrhoidal Artery  (Art.  Hasmor-
 rhoidea Inferior  Externa) to the inferior part of the rec-
 tum, and to the sphincter ani muscle.   This artery arises
after the internal pudic has returned within  the pelvis, and
consists sometimes in several branches.
  c.  The Perineal Artery (Art.  Perinea, Transversa Pe-
rinei) has its root  near  the origin of the transversus peri-
nei muscle,  and advancing obliquely forwards is distributed
in several ramifications to the muscles and  integuments  of
 the perineum, and to the posterior part of the scrotum.    It
 is unavoidably cut in the lateral operation for the stone.   In
 the female it goes  to the sphincter  vaginae and to the labi-
 um externum. 
      EXTERNAL ILIAC ARTERY AND ITS BRANCHES.   233

  d. When the internal pudic has got beyond the transver-
sus perinei muscle near the beginning of the crus penis, it
detaches, to the bulb of the  urethra, along the posterior
margin of the triangular ligament,  a branch which pene-
trates to the corpus spongiosum, and is minutely distributed
upon it,  some of its ramifications reaching to the  corpus
cavernosum.  This branch is called by  M. Chaussier Ure-
thro-bulbar, and instead of being always distinct, it on some
occasions  comes from the Perineal.
  e. At the under part of the symphysis pubis, between it
and  the back of the penis,  the internal pudic sends for-
wards, on the  dorsum of the  penis, a superficial  branch
(Ramus Superficialis Dorsi Penis.)  It advances to the
end of the  penis, under the skin, being parallel with its
fellow of  the other side, and near to it; sometimes the two
unite after a short course.  They are dispersed in branches
to the integuments, and to the elastic ligament of the penis.
  f. The Cavernous Artery of the Penis (Art. Cavernosa
Profunda  Penis)  may be considered as  the terminating
trunk of the internal  pudic.   It penetrates the corpus ca-
vernosum, beneath the symphysis of the pubes, and quick-
ly divides into  many ramifications.  The latter  advance,
and continue to subdivide upon the cells of the corpus ca-
vernosum, to which they are principally distributed; some
of them reach the corpus spongiosum urethras, and  others
anastomose with the  corresponding arteries of the other
side.


  SECT.  VIII.--OF THE EXTERNAL ILIAC ARTERY AND ITS
                       BRANCHES.

  The External  Iliac Artery  (Arteria Iliaca Externa)
extends from the bifurcation of the primitive iliac to Pou-
part's Ligament, where it is continued to the lower extre-
mity under the name of the femoral artery.  It looks like
the continuation of  the primitive iliac, and descends at the
superior strait of the pelvis along the internal margin of the*
  Vol. II.—-30 
234
CIRCULATQRY SYSTEM.
psoas magnus muscle.  In the early part of its course, it is
anterior to the external iliac vein; it then, as it approaches
Poupart's ligament, gets to its outer margin.  It is covered
by the peritoneum in front.   Where it passes beneath Pou-
part's ligament to the thigh,  it is about half way between
the anterior superior  spinous process  of the ilium and the
symphysis pubis, having the vein at its pubic margin and
the anterior crural nerve, half an inch from its iliac margin.
No branches of consequence arise before it reaches the cru-
ral  arch; it then sends off two,  the Epigastric and the Cir-
cumflex of the Ilium.

  The Epigastric  Artery  (Arteria  Epigastrica) arises
somewhat above the crural arch, at the line where the pe-
ritoneum is  reflected from the fascia transversalis upon the
iliac fascia.    It at first passes horizontally inwards, then
rises obliquely upwards and inwards, behind  the sperma-
tic  chord, at the pubic margin of the internal abdominal
ring.  Afterwards it reaches the external margin of the rec-
tus  abdominis muscle, two or three inches above the pubes;
ascending along it for a short distance, it then passes to its
posterior face,  and continues ascending above the umbi-
licus; where being divided  into several branches, it termi-
nates by anastomosing with  the lower ramifications of the
internal mammary artery.
  This artery is almost entirely spent  upon the anterior pa-
rietes of the abdomen, in ramifications, which anastomose
with the last intercostal and with the lumbar arteries.  One
of its small  twigs,  following the course of the  spermatic
chord, or of the round ligament, is distributed upon the
cremaster, the  tunica vaginalis, and  the scrotum  of the
male, and upon the mons veneris of the female.   In some
cases it gives off the obturator artery.

  The Circumflex Artery (Arteria Circumflexa Ilii) is of
the same size with the epigastric, and comes from the ex-
ternal iliac,  sometimes on a level with it, and on other oc-
casions lower  down,  even below the crural  arch.   It as- 
FEMORAL ARTERY.
235
cends outwardly towards the anterior superior spinous pro-
cess of the ilium, along the posterior margin of the crural
arch, and following afterwards the direction of the crista of
the ilium, it anastomoses with the corresponding branch of
the ilio-lumbar artery.
  The following branches come from it.   In the early part
of its course some unimportant twigs are sent to the adja-
cent muscles,  as  the sartorius, iliacus internus, and so on.
At the anterior superior spinous process it divides into two
branches, the  smaller ascends between the internal oblique
and the transversalis muscle, and is distributed upon them;
the  other branch, which is the continuation of the main
trunk  along the  crista of the ilium at  the  margin of the
iliacus internus muscle, sends ramifications to the latter,
and also to the posterior part of the  broad  muscles of the
abdomen, where  it  anastomoses with the other arteries of
this region.


                Of the Femoral Artery.

   The Femoral Artery (Arteria Femoralis, Cruralis) the
continuation of the  external iliac extends from the crural
arch to the perforation for its passage through the adductor
magnus, which is commonly one-third of the whole length
of the os femoris, above the knee joint.  This great trunk,
immediately below Poupart's ligament is very superficial, and
may be felt pulsating where it passes over the pubes.  It is
there covered  only by the common integuments and the fas-
cia femoris, which is thin;  it is bounded internally by the
femoral vein, externally by the crural nerve, is half way be-
tween  the  anterior superior spinous process and the sym-
physis of the pubes, and lies  upon the  internal face of the
psoas magnus over the interstice between it and the pecti-
neus.  In the upper third of its course the femoral artery
is at the inner  edge of the  rectus femoris, and  at a short
distance from it; it then inclines inwards, and occupies the
angle formed by the adhesion of the vastus internus to the*
adductor longus.   The sartorius,  at first, is remote  at its 
236
CIRCULATORY SYSTEM
outside, but this muscle inclining inwards in its descent gets
to the exterior margin of the artery, and afterwards covers
it completely for  the remainder of its course.  The femo-
ral artery is in front of the  femoral vein when it has des-
cended three or four inches below the crural arch; behind
the two is the arteria profunda.   When  the femoral artery
and vein reach the angle  formed by the vastus internus and
the adductor longus, they are covered by a strong inter-
lacement of tendinous fibres  from these muscles.
   The femoral artery sends  off these branches:

   1. The Superficial Artery of the Abdomen (Art. ad Cu-
tem Abdominis)  is small, and arises  at the lower margin
of Poupart's ligament; it goes upwards  towards the umbi-
licus, lies beneath the fascia  superficialis abdominis, and is
distributed to the integuments of this region.  One of its
ramifications goes to the inguinal glands.

  2. The External Pudic Arteries (Art.  Pudendas Ex-
temae) come from the femoral at the same point, and are
two or even three in number; they are of small size.  One
of them inclines inwards  along the groin, between the skin
and the  fascia  femoris, and is  distributed to the integu-
ments  of the pubes—to  those of the penis,—and to the
scrotum, or to  the  labium externum of  the female.   The
second, and the third when it exists, are rather lower down,
and are  dispersed upon very much the  same parts.   The
lymphatic glands of the groin  also derive their  supply of
blood from these external pudic arteries.

  3. The Profound Artery,  (Arteria Profunda Femoris)
the great muscular artery of the thigh, is but slightly infe-
rior in size to the femoral itself, and comes from the  latter
at the distance of from one to two inches below the crural
arch.   It lies behind the femoral artery,  and descends in
that situation between the insertion of the  adductor brevis
and the vastus internus muscle, to the  upper part  of the in-
sertion of the adductor longus.   In this course its size is 
PROFOUND ARTERY.
237
much diminished, by the origin from it of several conside-
rable trunks, as follows:
  a. The External Circumflex (Arteria Circumflexh Ex-
terna) though most  frequently a branch of the profunda,
sometimes comes from the femoral above or below it a short
distance.  It goes immediately outwards between the rectus
femoris muscle and the cruralis, giving off some inconside-
rable ramifications. While between these muscles it divides
into two, branches,  one of which ascends,  and the other
descends; the former is distributed to the anterior margins
of the gluteus medius and minimus, to the capsule of the
joint,  and the parts about the trochanter  major,  anasto-
mosing with  the gluteal and  the ischiatic.   It is said by
Meckel, that these anastomoses have been  found much di-
lated where the external  iliac artery has been taken up.
The descending branch is about the size of a crow quill,
or even larger; it first passes obliquely downwards between
the  rectus femoris and the cruralis, it then descends verti-
cally under the anterior margin of the vastus externus be-
tween it and the cruralis, to terminate at the knee, where
it becomes superficial and anastomoses with the articular ar-
teries.   It is, however, principally distributed to the vastus
externus and to the cruralis.
   b. The Internal Circumflex Artery (Arteria Circum-
flexa Interna) arises from the profunda,  near the external
circumflex, generally below it, but sometimes the reverse;
in some cases, it comes from the femoral artery itself,  near
the  crural arch.  It passes transversely inwards, and  dips
into the interstice between the pectineus and the psoas mag-
nus, after having given off some  small twigs to the heads
Of the adjoining adductors.   It then winds under the neck
of the os femoris and divides into two branches; the upper
one goes to the capsular ligament of the joint,  to the obtu-
rator externus muscle, anastomoses with  the obturator ar-
tery, and sends a branch behind the adductor brevis to the
upper part  of the adductor magnus;  the inferior branch
is larger than the other, it descends behind the adductor,
magnus and is distributed in branches to it, to the gracilis. 
238
CIRCULATORY SYSTEM.
and to the hamstring muscles, sending upwards some rami-
fications (rami trochanterici) to the parts about the trochan-
ter major, where they anastomose with the external circum-
flex artery.
   c.  Muscular branches of inconstant origin, and of incon-
siderable size, are sent from  the profunda to supply the an-
terior face of the adductor muscles.
   d. The Perforating Arteries (Rami Profundi Perforan-
tes) obtain  the name from their perforating the adductor
magnus, which they do near the linea aspera, so as to get
to the back of the thigh.   They commonly are four in num-
ber,  and as they come  off successively from the profunda,
they are designated  numerically.   In some cases, however,
they are reduced to one, by being concentrated in a com-
mon trunk, which,  penetrating high up the adductor mag-
nus,  and afterwards descending on its posterior face, is dis-
persed upon the muscles on the back of the thigh.
   The First Perforating Artery arises somewhat below the
trochanter minor, and penetrates the adductor magnus a lit-
tle below its superior margin.  One of its branches ascends
towards the trochanter major, where it anastomoses with
the external circumflex and with the  gluteal, while another
descending is spent  upon the heads of the flexor muscles of
the leg.
   The Second Perforating Artery gets to  the back of the
thigh, at the  lower  margin of the insertion of the gluteus
maximus into the linea aspera, being  distributed in that re-
gion and to the corresponding portion of the long head of
the biceps flexor cruris.
   The Third Perforating Artery penetrates the adductor
magnus somewhat below the commencement of the short
head of the biceps, and is dispersed upon the adductor and
the adjacent portion of the flexor muscles.
   The Fourth Perforating Artery penetrates the insertion
of the adductor magnus an inch and a half above the open-
ing in it, for the femoral artery;  it, in the same way, sup-
plies the posterior face of the adductor and the adjacent
muscles. 
POPLITEAL ARTERY.
239
  As a summary, it will be readily understood that the pro-
funda is, in this way, through the external and the internal
circumflex, and through the perforating arteries, distributed
upon all the large muscles of the thigh.

  After  the  origin of  the  profunda, the Femoral Artery
gives off,  at different points of its course to the  opening of
the adductor magnus, several twigs, the size of a large knit-
ting needle, which go to the sartorius, the gracilis, the ad-
ductors,  and the extensors on  the front of the  thigh; but
they are too inconstant  to require more  particular descrip-
tion.

  The Anastomosing Artery (Arteria  Anastomotica) is
the last branch of the femoral,  and arises just before it perfo-
rates the adductor magnus.  It descends  to the knee in front
of the tendon of the  latter, concealed by the  internal mar-
gins of the vastus internus muscle.   It sends off many small
twigs  to  the  adjacent  muscles, and terminates  below by
anastomosing with the internal articular arteries.   It is
about the size of a crow quill.   ,

  The Popliteal Artery (Arteria Poplitasa) is the conti-
nuation of the femoral, after the latter has passed through
the  tendinous  insertion of the adductor magnus, and  ex-
tends from this point to the opening in  the interosseous li-
gament of the leg, just  below the head of the tibia.   It first
of all passes from the internal margin of the os femoris, to
the notch between  the condyles, being there  placed in the
middle between the  internal and  the external hamstring
muscles, and surrounded by a mass of adipose matter which
fills up the hollow of the ham.  It is in contact, anteriorly,
with the knee joint, and  a little below  the latter with the
popliteus muscle, descending there between the heads of the
gastrocnemius.  It is covered in the greater part of its ex-
tent, posteriorly, by  the popliteal  vein  and by the sciatic
nerve, the latter being more superficial than the vein.
  The popliteal artery sends off some small branches to the
hamstring muscles and  to  the parts contained between the 
240
CIRCULATORY SYSTEM-
latter, which are too irregular and inconstant for descrip-
tion.  The following arteries also come from it:

   1.  The Superior Internal Articular Artery (Art. Articu-
laris Superior Interna) arises at or above the internal con-
dyle, and  frequently consists  in two  trunks.  It passes
through the tendon of the adductor magnus, just above the
condyle; it then begins to distribute itself in branches, some
of which are spent upon the lower part of the vastus internus
muscle, and others upon the superior internal part of the
knee joint.

   2.  The Superior External Articulating Artery (Art. Ar-
ticularis  Superior  Externa) arises  from  the  popliteal,
somewhat above the external condyle of the os femoris.  It
winds horizontally, above the external condyle, around the
bone, between  it and the lower part of the biceps flexor
cruris, and is then distributed also in two orders of branches,
some of which supply the lower part of the  vastus externus
muscle, and others the superior external portion of the knee
joint.

   3.  The Middle Articular Artery (Art. Articularis Me-
dia) is smaller  than either of  the above,  and sometimes
comes from one of  them, but generally from the popliteal,
on a line with the articulation of the knee. It is distributed
to the posterior part of the capsular ligament, to the crucial
ligaments, and  to the corresponding adipose matter.

   4.  The Inferior Internal Articular Artery (Art.  Articu-
laris Inferior Interna) arises on a  line with the inferior
part of the internal  condyle, sometimes lower down.  Its
origin is very much concealed by the internal head of the
gastrocnemius; it passes beneath the latter, and  then be-
tween the internal lateral ligament of the knee and the head
of the tibia, consequently is covered by the internal ham-
string muscles.  It afterwards ascends towards the patella,
and is distributed in numerous branches to  the inferior in- 
TIBIAL ARTERY.
241
ternal part of the knee joint, and to the adjacent portion of
the tibia.

   5. The Inferior External Articular Artery (Art. Articu-
laris Inferior Externa) arises near the last, below the ex-
ternal condyle, being concealed by the belly of the plantaris.
It passes horizontally, or nearly so, between the popliteus
and the  outer head of the gastrocnemius,  and  afterwards
beneath  the tendon of the biceps and  the  external lateral
ligament of the joint,  around the external face of the head
of the tibia.  It  gives small branches to these several parts,
and is then distributed, by two orders of ramifications, to
the superficial and to the more deeply seated parts at the
external inferior portion of the knee joint.

   These  several articular arteries anastomose freely with
each other, and  are minutely ramified on the knee joint and
the contiguous  structure.   They also anastomose with the
long descending branch of the external circumflex of the
thigh, with the anastomotica of the femoral and with the
tibial recurrent.

   6. The Gastrocnemial  Arteries (Arteriae Gemellae) are
two in number, one for each head of the gastrocnemius. They
arise commonly between the superior and the inferior arti-
cular arteries, and are about the same size.  They penetrate
into the  muscle and supply it with blood, terminating their
course near the  lower part of its bellies.
   Moreover some small  branches, which go to the contigu-
ous muscles, are frequently observed here;  also, the nutri-
tious artery of the  tibia.    But their number and condition
are very inconstant.  Near the head of the  fibula, branches
go from  the popliteal artery to the upper end of the soleus
muscle.                                          .
   Generally on  a level with the aperture in the upper part of
the  interosseous ligament, but sometimes an inch  or two
higher up, the popliteal  artery terminates, by dividing into
two large trunks, the  Anterior and the Posterior Tibial.
   Vol. IT.—31 
242
CIRCULATORY SYSTEM.
  The Anterior Tibial Artery (Art.  Tibialis  Anterior)
passes forwards through the foramen of the interosseous liga-
ment, just below the head of the fibula, and runs down the front
of the leg and foot, as far as the base of the metatarsal bone of
the great toe.   In this course its  relative situation is as fol-
lows. It rests upon the front of the interosseous ligament of
the leg, on a line drawn from the middle anterior part of the
head of the fibula to the middle of the ankle joint. Superiorly
it is bounded on the tibial side by the tibialis anticus muscle,
and on the other by the extensor longus  digitorum; lower
down on the leg, the place of the latter is supplied  by  the
extensor pollicis pedis.  Somewhat above the ankle joint the
artery, leaving the interosseous ligament, rests upon the front
of the tibia, and then gets to the top of the foot, between the
joint  and the annular ligament.   Under the ligament it is
crossed by the tendon of the extensor pollicis, which  gets to
its  inner side,  and afterwards  continues so.   The anterior
tibial nerve adheres to it, in its whole length.
  The following  branches  come from  tne anterior tibial
artery:

   1.  The Recurrent  Tibial  (Art. Tibialis Recurrens) as-
cends through the upper extremity of the tibialis anticus mus-
cle, having come off from the anterior tibial immediately upon
the latter  getting to the front of the leg.  Several small
ramifications pass  from it to the heads of the contiguous mus-
cles on the tibia,  and to  the lower  part of the knee joint,
where it anastomoses with the lower articular arteries of the
knee.

   2.  Several small arterial twigs are afterwards sent to the
muscles and to the  periosteum of the  leg, as the anterior
tibial descends, but  they  are two inconstant in size and po-
sition to require description.

    3. The Internal Malleolar Artery (Art. Malleolaris In-
 terna) arises from the anterior tibial an inch or two above
 the ankle joint.  It descends inwardly between the tibia and 
TIBIAL ARTERY*.
243
 Ihe tendon of the tibialis anticus, and having gained the in-
 ternal malleolus, is distributed by branches upon it and upon
 the adjacent portion of the articulation.

   4.  The External Malleolar Artery (Art. Malleolar Ex-
 terna) consists  most commonly in two arterial twigs  of
 small size, but frequently in one only.   It arises in front of
 the ankle joint, and going outwardly between it and the ten-
 dons of the extensor digitorum longus, is spent upon the ex-
 ternal face of the articulation, where it inosculates with the
 peroneal artery.
   This artery is sometimes of  considerable  size, in which
 case it also supplies the outer part of the tarsus,  and is a
 substitute  for the next.

   5.  The Tarsal Artery  (Arteria Tarsea) arises from the
 anterior tibial, somewhat below the ankle joint near the sca-
 phoides, and, going outwardly beneath  the extensor brevis
 digitorum  muscle, it is distributed in branches near the ex-
 ternal ankle, and upon the outer upper surface of the tarsus.
 It anastomoses with the external malleolar, with the exter-
 nal plantar, and  with the metatarsal artery.
   Some small branches also pass from the anterior tibial at
 this point to the  upper internal face of the tarsus.

   6.  The Metatarsal Artery (Art. Metatarsea) arises just
 below the  last.   It is directed forwards and  outwards be-
 neath the extensor brevis muscle, and forms  a sort  of arch
 at the roots of the metatarsal bones.   It furnishes several
 ramifications to the upper surface of the tarsus and the con-
tiguous parts; amongst them is an interosseal artery for each
of the three outer interosseal spaces.  These  arteries com-
municate, by small anastomoses, with the arteries of the sole
of the foot, both at the bases and at the ends of the metatar-
sal bones, and terminate in front  by supplying the backs of
the small toes.
  This artery is sometimes a branch of the tarsal. 
244
CIRCULATORY SYSTEM.
  7. The Dorsal Artery of the Great Toe (Art.  Dorsalis
Hallucis) arises from the anterior tibial at the root of the
first metatarsal bone.   It runs along the superior face of the
first metatarsal interval, and, having reached  the anterior
end of it, divides into two branches, one of which goes to the
back of the great toe and the other to the tibial margin of the
next toe.

  The Anterior Tibial, in its course from  the ankle joint to
the base of the first metatarsal bone, is sometimes called pe-
dal (Arteria Pedioea;) at the posterior end of the first me-
tatarsal interval, being still of considerable size, it  sinks
down to the sole of the foot, and joins itself to the external
plantar artery at this point.
   It frequently happens that the anterior tibial being  small
in its course down  the leg, is joined by the continued trunk
of the  peroneal, which perforates the interosseous ligament
somewhat  above the ankle joint.   Afterwards the  trunk
formed by this union,  being of  considerable size, follows
the course and has  the distribution mentioned.

   The Posterior Tibial Artery (Arteria  Tibialis Postica)
sometimes called,  at its commencement till  it  gives  off
the peroneal, tibio-peroneal; extends from the head of the
tibia to  the sinuosity of the os  calcis, in  a line from the
middle of the ham to the internal ankle.   It is at the tibial
side of the back of  the leg, on the posterior face of the flexor
longus digitorum  muscle,  and  covered  by the fascia  of
the  latter.  In the two superior thirds of its course, it is
concealed behind by the gastrocnemius and the solaeus mus-
cles; in the inferior third, it is at the internal margin of the
tendo  achillis. At the ankle joint, before it passes into the
sinuosity of the os calcis, it is between the tendon of the
tibialis posticus and that of the flexor longus pollicis pedis,
being covered by the laciniated ligament.  It is accompanied,
at its external margin, by the posterior tibial nerve.
   The posterior tibial artery is distributed  after the follow-
 ing manner: 
TIBIAL ARTERY.                245
  1. The Peroneal  Artery (Arteria Peronea) is its  first
branch of any importance, and is but little smaller than the
continued trunk.  It arises an inch or two below the ante-
rior tibial,  and extends, on  the posterior face of the leg, to
the external ankle.  It is in some measure concealed by the
posterior side of the fibula, being placed there between the
origin of the flexor  longus pollicis muscle and the external
edge of the tibialis posticus.  It  is consequently covered be-
hind by the flexor longus pollicis, by the soleus, and by the
gastrocnemius; it is  therefore deep and of extremely difficult
access in the living  body.
   In  this course it  sends small  branches to the gastrocne-
mius, to the soleus,  and to the other contiguous muscles on
the back of the leg.   After having descended two-thirds of
the length of the fibula,  it divides into an anterior and a
posterior branch.  The former traverses the interosseous li-
gament, and, descending in front of it covered by the mus-
cles which arise from the lower part of the fibula, is distri-
buted upon  the upper external part of the foot near the
ankle joint.  The posterior branch continues in the primitive
course  of the peroneal artery at the internal posterior mar-
gin of the fibula, and, descending behind the tibio-peroneal
articulation, reaches the  external  face of the os calcis; it
detaches several small ramifications to the contiguous mus-
cles; and, upon the os calcis, is divided into twigs which
supply the adjacent parts and  the integuments below the
external ankle.

   2.  In the descent of the posterior tibial artery to the hol-
low of the  os calcis, it detaches several small muscular
branches, principally to the tibialis posticus and to the flex-
ors of the  toes. One twig,  which is the nutritious artery of
the tibia,  comes from its  upper part when not furnished
from the popliteal artery,  and  enters  the  foramen on the
posterior surface  of the bone.
   While the posterior tibial is in the hollow of the os calcis,
between it and the abductor muscle of the  great toe, it fur-
 nishes  some small twigs to the contiguous muscles, and to 
246
CIRCULATORY SYSTEM.
 the integuments of the sole of the foot; it then divides into
 two branches, the Internal and the External Plantar Artery.

   The Internal Plantar Artery (Art. Plantaris Interna) is
 much smaller than the other.  It advances between the ab-
 ductor pollicis pedis and the internal inferior margin  of the
 sole of the foot, and  terminates at the anterior end of the
 first metatarsal bone, by joining the  internal digital artery
 of the great toe.  In this course, it sends, continually, small
 ramifications to the muscles of the great toe and to the flexor
 brevis digitorum pedis. One of the largest of these ramifica-
 tions comes off near the  os scaphoides, and cruises  along
 the internal margin of the  abductor pollicis to its anterior
 end; another becomes superficial on the sole of the foot, be-
 tween the abductor pollicis and the flexor brevis,  and goes
 forward as far as the other.

   The External Plantar Artery (Art. Plantaris Externa)
 is the continuation of the posterior tibial, and diverges from
 the internal plantar towards the outer margin of the sole of
 the foot, between the flexor brevis digitorum pedis and the
 flexor accessorius.  Having reached the internal margin of
 the abductor  minimi  digiti, it advances along the latter to
 the base of the metatarsal bone of the fourth toe; it then
 makes a curvature forwards and inwards across the meta-
 tarsal bones,  between the tendons of the flexor longus and
 the interosseous  muscles, to the first metatarsal  interval,
 where it is joined by the anterior tibial artery from above.
 This curvature is the Arcus Plantaris,  of which the conca-
 vity is behind and inwards.
   The external plantar artery is distributed as follows:
   Shortly after its origin, it detaches a branch which goes
backwards and outwards, and which, keeping close to the
os calcis in front of  its tuberosity, is distributed to the
heads of the  muscles arising from it, and to the outer sur-
 face of the heel; it also sends an arteriole along the  external
 edge of the abductor minimi digiti.
   At the base of the fourth metatarsal  bone, arises a branch 
TIBIAL ARTERY.
247
called the External Digital  Artery of the Little Toe.  It
goes at first deeply along the internal margin of the mus-
cles situated on the fifth metatarsal bone, and afterwards, at
the head of the latter, it gets between them and the bone,
and is distributed along the external margin of the little toe.

   The four Digital Arteries of the foot arise next succes-
sively from the arcus plantaris, at or near the metatarsal
intervals.  They run along the inferior surface of the inter-
osseous muscles, getting to the bases of the first phalanges
above the transversalis pedis. Each artery there, bifurcates
so as to supply the opposed  surfaces of the adjacent toes.
   The digital  artery of the  first  metatarsal interval which
comes from the internal extremity of the arcus plantaris,
where the anterior  tibial artery joins the latter;  goes for-
wards concealed by the flexor brevis of the great toe; just
behind the sesamoid bones, it sends a branch which sup-
plies the  internal  side of the great toe, being  its internal
digital artery, and anastomoses  with the internal plantar
artery. What remains of it, is still a trunk of considerable
magnitude, which  advancing to the space between the first
phalanges of  the  great toe and of the toe next  to it, there
bifurcates, as mentioned, so as to supply the opposed sides
 of these two toes.

    The Perforating Arteries, as they are called, are of two
 kinds, the anterior  and the posterior.   The former arise
from the convexity of the plantar arch, and being destined
principally to the interosseous muscles, anastomose at the
anterior end of the latter with the branches from the meta-
tarsal artery, which supply their superior surface.  The pos-
terior perforating arteries come also from the plantar arch,
and penetrating the posterior end  of the interosseous spaces,
anastomose also with the metatarsal arteries on  the dorsum
 of the foot.
   The preceding trunks of  the internal and of the external
 plantar arteries are  the principal ones which are found in
 the bottom of the foot, but from them there arise an  im- 
248
CIRCULATORY SYSTEM.
mense number of arterioles; which, descending vertically
between the interstices of the muscles and of the aponeu-
rosis plantaris, supply the adipose matter and the skin of the
sole of the foot, so as to render them extremely vascular.
                   CHAPTER III.

                     OF THE VEINS.

  The veins of the body, assembling from different points,
unite successively into the ascending and into the descending
vena cava, which discharge their blood into the right auricle
of the heart.   The veins of the head, of the upper extremi-
ties, and of the thorax, run into the descending cava, while
the  veins of the abdomen and of the lower extremities con-
cur  to form the ascending cava.
    SECT. I.--OF THE VEINS OF THE HEAD AND NECK.

  Many of these veins are described elsewhere with the en-
cephalon and with the eye, to which account the reader is
referred.   The others are more superficial,  and arise as fol-
lows:
  The Facial Vein (Vena Facialis) observes the course of
the facial artery,  being placed behind the latter.  It arises
upon the forehead by a considerable number of roots which
unite into a single trunk called the frontal vein.  This vein
descends from the forehead, over the root of the nose along
the internal canthus of the orbit.   It there receives re-en-
forcements from the eyelids, and anastomoses with the oph-
thalmic veins; descending afterwards, in the same way with
the facial artery,  and  taking the name of facial vein, it  re-
ceives  successively the veins from the nose, from the outer 
VEINS OF THE HEAD AM) NECK.
249
side of the  orbicularis palpebrarum,  from the upper and
lower lips, and from the muscles and the integuments of the
face.   It descends to the neck at the anterior margin of the
masseter muscle, and is then augmented by the ranine, the
submental, and the inferior palatine ve*ins, and immediately
afterwards goes into the internal or  the external  jugular
vein.
  The Ranine Vein (Vena Ranina) arises  at the point of
the tongue, and then goes along its under surface, where it
can be readily seen by turning up the end of the tongue.  It
joins the facial near the posterior margin of the mylo-hyoi-
deus muscle.
  The Submental Vein (Vena Submentalis) arises by ra-
muscles from the sublingual and submaxillary glands,  and
from the contiguous muscles.  It joins the facial vein a lit-
tle  below the last: sometimes it runs into the superior thy-
roidal vein.
  The  Inferior Palatine  Vein (Vena Palatina Inferior)
arises principally from the soft palate and from the tonsil
gland, but receives a few  twigs from  the  contiguous parts.
It corresponds with the inferior palatine artery and descends
the pharynx along side of it, and terminates in the trunk of
the facial near the last.
  The Lingual Vein (Vena  Lingualis)  has its origin from
a plexus of veins situated  on  the root of the tongue under its
lining membrane, between the epiglottis and the foramen
caecum:  branches are  also  sent  to it from  the muscular
structure of the tongue, from the sublingual gland, and from
the adjacent muscles, and  it anastomoses with the vena ra-
nina.  It goes backwards  between the hyo-glossus and the
mylo-hyoideus muscles along the superior margin of the os
hyoides, and then discharges into the internal jugular vein
near the facial.
  The Pharyngeal Vein  (Vena Pharyngea) arises from a
plexus of veins  belonging to the pharynx, and discharges
either into the lingual or into the internal jugular near it.
  The Superior Thyroid Vein ( Vena Thyroidea Superior)
corresponds with the distribution of the superior thyroid ar-
  Vol. II.—32 
250
CIRCULATORY SYSTEM.
 tery in the origin of its primitive roots.   Having collected
 the latter into one  or  more trunks, it passes upwards and
 backwards beneath the sterno-hyoid and thyroid muscles,
 and  discharges itself into the upper  part of the internal
jugular, or into one of the large branches of the external
jugular.
   The  Occipital Vein  (Vena Occipitalis) arises from the
 branches of the occipital artery, and  following the course of
 the latter, beneath the  muscles connected with the mastoid
 process of the temporal bone; it is discharged  into the upper
 part of the internal jugular or of the external, more rarely
 into the litter.
   The  Diploic Veins (Venae Diploicas) have been described
 in the account of the bones of the cranium as  situated be-
 tween the two tables in the diploic structure, and commence
 by very  fine capillary tubes from  its lining  membrane.
 The one in the frontal bone discharges itself  into the fron-
 tal vein, that in the occipital  bone into the occipital vein,
 and the two in the parietal  bone into the deep temporal
 veins.   They do not open each by one orifice,  but by se-
 veral, which makes their termination  not very distinct or
 abrupt; besides which,  they communicate freely by a crowd
 of ramuscles, with the  veins of the scalp on the outside, and
 with those of the dura mater internally.
   The  Superficial  Temporal  Vein (Vena Temporalis Su-
perficial) corresponds with  the temporal artery, and takes
 its rise  from  the terminating  ramifications of the latter.  It
is immediately below the skin.  Its branches communicate
 freely with each other, and with the branches of the frontal
 and of  the occipital veins: at the zygoma it receives the
 trunk of the Middle Temporal Vein, which  collecting the
 blood from the temporal  muscle and  other parts within the
 zygoma, perforates  the temporal fascia to discharge  itself
 into the superficial temporal vein.
   The Temporal Vein, (Vena Temporalis,) which is  formed
 by the junction of the Middle and the Superficial Temporal,
 descends over the  root of the zygoma, in company with
 the artery, and penetrates like the latter through the sub-
 stance of the parotid gland.   It is joined near  the neck of 
              VEINS OF THE HEAD AND NECK.          251

 the lower jaw  by the internal maxillary vein.   It  is also
 joined, in its descent through the parotid gland, by the an-
 terior auricular veins,  by the parotid veins, and by the
 transverse facial, all of which correspond with  the arteries
 of the same name.   The temporal vein, on issuing from the
 parotid gland, immediately afterwards becomes  the Exter-
 nal Jugular.
    The Internal Maxillary Vein  (Vena Maxillaris  Inter-
 na) is derived  from the terminating ramifications of  all the
 arteries into which the internal maxillary is  split; it is there-
 fore composed of the spheno-palatine vein, which brings the
 blood from the nose, of the infra-orbital, of the pterygoids,
 inferior maxillary, deep-seated temporal, and so forth, with
 the exception of the vein which  might belong to the mid-
 dle artery of the dura mater, but which does not exist ac-
 cording to Portal and to Hippolytus Cloquet.   But,  by the
 aid of the spheno-palatine vein, the internal maxillary com-
 municates with the sinuses in the bottom of the cranium,
 by branches called the Emissary Veins of Santorini,*  which
 pass through  the foramen ovale, rotundum, and spinale. It
 also communicates with the plexus  of veins on the side of
 the Pharynx.

   The External Jugular Vein (Vena Jugularis Externa)
 is the continuation of the temporal.  It descends on the neck
 almost vertically, between  the platysma myoides and the
 sterno-mastoideus, in the direction of the fibres of the first,
 and crossing those of the latter obliquely.   Just behind the
 clavicle,  at the external margin of the sterno-mastoideus, it
 opens into the subclavian vein, in  front of the scalenus  an-
 ticus muscle.   Sometimes, instead of one trunk only, there
are two or three, which unite  at a variable distance above
the subclavian.  This vein varies also in its size, and in the
branches from which  it is made up;  sometimes it receives
the facial  vein,  and on other occasions the  latter runs into
the internal jugular.   The temporal  vein is  also sometimes
continued  in part or wholly into the internal jugular.  The
* Obs. Anat. chap in. p ~4. 
252
CIRCULATORY SYSTEM.
condition and arrrangement of the internal and external ju-
gulars are indeed so inconstant, in regard to the trunks that
compose  them, that it is scarcely  possible to give  more
than a very general description of them with tolerable accu-
racy.
   The external jugular,  in going down the neck, anasto-
moses more or less with the internal jugular, either directly
or by its branches: one of these  anastomoses is found near
the angle of the lower jaw, about the  trunk of the  facial
vein, and  is  so large as  to explain the difference of opi-
nion  among anatomists in regard to the latter's termination.
Sometimes the occipital vein,  or a large trunk from it, joins
the external jugular.  At the lower part of the neck, the
external jugular is  augmented by the superficial cervical
veins.   Some of these come from  the lower part  of the
neck, near the shoulder, and join the jugular just above the
clavicle;  others are placed on the lower front part of the
neck, above the sternum, and there form with each  other
a remarkable  and an irregular plexus,  consisting in nume-
rous meshes.  It frequently happens that the external jugu-
lars of the two sides, just before they terminate, anastomose
with  each other by a large horizontal trunk, which runs
just above the end of the sternum, in front of the sterno-
mastoid, sterno-hyoid, and the thyroid muscles; this trunk,
on other occasions, goes  more  deeply, and behind  these
muscles," from one subclavian vein to another,  or to a jugu-
lar; its mode of attachment is indeed much varied:  when
it exists, however, it frequently receives several of the su-
perficial veins of the neck, and the inferior thyroidal.

   The Internal Jugular Vein (Vena Jugularis Interna)
extends from  the basis of  the  cranium to the internal mar-
gin of the first rib, at the insertion of the scalenus anticus
muscle.   The lateral sinuses  of the dura mater, receiving
ultimately all the blood of the brain, of the eye, and a por-
tion of that of the nose, convey it from the cranium through
the posterior foramina lacera,  where they are joined to the
upper end of the internal jugular veins, the lining  mem-
brane of each  sinus beine  continuous with that of its respec- 
VEINS OF THE HEAD AND NECK.          253
tive veins.  Each vein is somewhat enlarged  at its  com-
mencement, which is therefore called its Gulph or Sinus;
the right vein is frequently larger than the left.  The  in-
ternal jugular then descends in front of the transverse pro-
cesses of the vertebrae of the neck, on the outer side of  the
internal  end of the primitive carotid artery,  and of  the
pneumogastric nerve.   It is concealed above by the styloid,
process of the temporal bone, aad the muscles  belonging to
it;  it is crossed half way down  the neck by the omo-hyoi-
deus muscle; and, in  the greater part of its course, is  be-
neath, and  nearly parallel  with, the  anterior  edge of  the
sterno-mastoideus.  Having got behind the sternal end of
the clavicle, it is joined at the internal edge of the scalenus
anticus by  the subclavian vein, and the union of the  two
forms the vena innominata.
   The internal Jugular receives frequently a  large anasto-
motic branch from the external jugular, at the under margin
of  the parotid gland,  between the digastric muscle and the
lower jaw, and it is in this vicinage that it is  generally re-
enforced by the Occipital; the Lingual; the  Facial; the Pha-
ryngeal; and the  Superior Thyroidal veins, that have been
described.

   The Vena Innominata or Brachio Cephalic Vein, is the
 trunk formed on  either side by the junction of the subcla-
 vian with the internal jugular. . On the right  side it looks
like the continuation of the internal jugular, and descends
in  contact  with  the  right pleura, behind the  right side of
the sternum, for the distance of an inch or thereabouts.  On
the left side it crosses  behind the superior  end of the ster-
num, descending obliquely in this course, from  left to  right,
until it joins the  trunk on  the  right side.  It  lies  in front
of  the great vessels proceeding from the arch  of the  aorta;
and is much longer than the trunk of the other side.

   The Vena Cava Superior or  Descendens arises from the
junction of the two venae innominatae.  It begins between
 the cartilage of the first rib on  the right side,  and the arch 
254
CIRCULATORY SYSTEM.
  of the aorta, and  descends to the superior posterior part of
  the right auricle,  into which it empties itself.   Its course ia
  not entirely vertical, but inclining somewhat to the leftside
  and forward.   It is about three inches long.   The superior
  third of it is free, is in contact on the right with the pleura,
  and on the left with the arteria innominata; the remaining
  portion of  it is invested  by the  pericardium, and  has the
  aorta on its left anterior face.*
    The following venous trunks discharge into the venae in-
  nominatae, or into the descending cava.   The inferior Thy-
  roidal;  the Vertebral; the Superior; Intercostal; the In-
  ternal Mammary;  the Vena Azygos; and  some others of
 smaller size.

    1. The Inferior Thyroid Vein (Vena Thyroidea Infe-
 rior)  arises from the inferior part of the  thyroid gland, by
 many small roots,  which  anastomose with those of the op-
 posite side.   It descends  in front of the  trachea, involved
 in  the loose cellular and  fatty matter lying  upon  it,  and
 empties itself into the  left  brachio-cephalic vein.
   There is  occasionally another thyroid  Vein, called  the
 middle, which  discharges  itself into the  lower part of  the
 internal jugular.

   2. The Vertebral Vein (Vena Vertebralis) is placed in
 the same canal with the vertebral artery.  At its upper ex-
 tremity it anastomoses  with the occipital sinus,  by a branch
 lodged in the posterior condyloid foramen.  In its  descent
 of the canal of the transverse processes, it  communicates at
 each intervertebral foramen with the vertebral sinuses, and
 also receives a branch  from the muscles  of the neck.  It
issues at the sixth transverse process,  and going on the right
side behind the subclavian  artery,  but on the left in front
of it, it is  finally emptied into  the commencement of the
vena innominata.

  * In some very rare cases there have been two descending vena cavs,
 one for the right side and the other for the left.  J. F. Meckel. 
     ' •      VEINS OF THE HEAD AND NECK.         255

  3. The Superior Intercostal Vein  (Vena Intercostalis
Superior) is on  the  right  side an  inconsiderable trunk,
sometimes deficient, which commences by branches belong-
ing to the two first intercostal spaces, and empties into the
vena innominata just below the vertebral.   On the left side
it is much larger,  and arises from the six or eight superior
intercostal spaces.  It lies on the left side of the bodies of
the upper dorsal vertebrae, and at each intercostal space,  as
it ascends,  receives its contribution of an intercostal vein,
corresponding with the intercostal artery;  it  also receives
branches from  the cesophagus, and  about the  third dorsal
vertebra the left bronchial vein  is discharged into  it.  Is-
suing from the thorax  above, it discharges into the left vena
innominata  near its commencement.

  4.  The Internal Mammary Vein [Vena Mammaria In-
terna) arises from the terminating branches of the internal
mammary artery,  and in its situation and course corres-
ponds with  the latter.   It is re-enforced by small branches
from  the diaphragm,  the  pericardium, and  the thymus
gland.  Each internal mammary vein discharges  itself on
its respective side into the vena innominata near the supe-
rior intercostal.

   5.  The Vena Azygos is placed in the posterior medias-
tinum, on the right  anterior margin of the Dorsal Verte-
brae, and discharges itself in making an  arch forwards over
the root of  the right  lung,  into the descending cava, just
above the introduction of the latter into the  pericardium.
Its  orifice there is .supplied  with a membranous duplicature
or valve, which prevents the blood once discharged from
re-entering  it.  The valve  is sometimes double,  and also
somewhat removed from the orifice   It was the observa-
tion of these valves, first of all, which called the attention
of Sylvius and of Charles Etienne  to  their existence  in
other veins.
  This vein  begins in the  abdomen,  either by an anasto-
mosis with  the ascending cava, or with the upper lumbar
vein; it then ascends into the thorax through the aortic ori- 
256
CIRCULATORY SYSTEM.
fice of the diaphragm,  and continuing to  mount upwards
beneath the pleura, it lies on the right side of the thoracic
duct and crosses in front of the intercostal arteries of the
right side.   In this course it receives from the ten inferior
intercostal  spaces of the right side,  their  respective inter-
costal veins corresponding in their  origin and course with
the intercostal arteries.  About the sixth vertebra of the
back it receives a trunk  (Vena Hemiazygos) which is
formed from the four or six lower intercostal veins of the
left side, and commences in the abdomen,  also, by an anas-
tomosis with  the  left emulgent vein  or the  left superior
lumbar, and gets into the thorax either through the aortic
orifice  of the diaphragm, or through  a special opening to
the left of  it.   The vena azygos also  receives some small
ramifications from the oesophagus, and near the fourth dor-
sal vertebra, the right bronchial vein is discharged into it.
Other small ramifications join it from  the parietes of the
descending cava; of the aorta; and of the right pulmonary
artery.  Branches  also proceed to it, or to the  intercostal
veins, from the interior of the vertebral canal at each inter-
vertebral foramen.
  This vein is commonly spoken of by anatomists, as form-
ing a great anastomosis between the ascending and the de-
scending cava.   The tendency to establish  this anastomosis
is strikingly confirmed  by a preparation made sixteen  or
seventeen years ago  by myself, and  now in  the Wistar
Museum of the University,  where the ascending cava, in-
stead of emptying,  as usual, into the lower  part of the right
auricle, ascended on the right side of  the  dorsal  vertebrae,
and supplanting in situation and office the vena azygos, dis-
charged itself into  the descending cava, in a manner cor-
responding with the vena  azygos,  by making a curvature
forwards over the root of the right lung.

  6.  The Sinuses of the Vertebral Column* (Sinus Colum-
nae Verlebralis) are situated in the vertebral cavity  on the
posterior face of the bodies of the vertebrae, and in front of the

     * G. Breschet, Essai sur les Veines du rachis.  Paris, 1819. 
VERTEBRAL SINUSES.               257
dura mater of the spinal marrow.  They are two long veins,
one at each margin of the posterior vertebral ligament, and
extend from the foramen magnum occipitis to the inferior
end of the sacrum.   They are maintained  in their  places
by a loose  cellular tissue between  the  bones and the dura
mater, and therefore, unlike the sinuses of the brain, are en-
tirely independent of the dura mater.
  These sinuses are small where they begin in the sacrum,
and are there merely two  cylindrical veins surrounded by
the loose cellular matter,  and which have an anastomosis
between them.   In ascending the  spine they enlarge,  but
not continually,  as they are  somewhat smaller in the cer-
vical than  in  the dorsal vertebrae.   On the  body of each
vertebra they are rather larger than on the inter-vertebral
substance, this gives them a  knotted appearance, which is
especially distinct in the loins.
  At the  middle of  each  vertebra they are joined to one
another by transverse branches, which pass beneath  the
posterior vertebral ligament,  and receive the veins belong-
ing  to  the cancellous structure  of the bone.  Externally
they communicate with the  vertebral  veins  in  the trans-
verse processes of the neck, with the intercostal, and with
the lumbar veins, as an opening occurs between the adja-
cent vertebrae.  They also receive many delicate veins from
the dura mater  of the spine.  These two trunks terminate
at their upper end by an anastomosis, through the anterior
condyloid foramen, with the internal jugular, they also ter-
minate by anastomosis with the anterior occipital sinus and
with the vertebral veins.
  From the arrangement of these  sinuses, it appears that
each bone of the spine has its own venous system or  circle;
which also is the case in  regard to the corresponding section
of medulla spinalis in early life, when it occupies the whole
length of the spine.   Each  of these circles, by the free-
dom of their anastomoses, therefore, forms a link in a long
chain of venous  circles  belonging  to the  structure of the
spine.
  Vol. II.—33 
^58
CIRCULATORY SYSTEM.
   SECT. II.--OF THE VEINS OF THE UPPER EXTREMITY-

  The veins of the  upper extremity are superficial and
deep-seated, and arise from the distribution of the axillary
artery.
  The Deep-Seated Veins are found in company with each
arterial ramification, there being two veins to one artery ge-
nerally.   We thus  have them observing the  course of the
arteries of the hand, of the  fore-arm, of the arm, and  of the
shoulder.   At the bend of  the arm, the two radial and the
two ulnar veins coalesce into  the two brachial veins, which
attend  the brachial artery,  one  on each of its sides, and at
intervals throw anastomotic branches across it. Sometimes,
but one of these trunks exists, with the exception of the
lower  part of the arm, where there  are  most commonly
two.   The trunk (or trunks,  as the case may be)  is joined
by the basilic vein,  at a  point varying from  the middle of
the arm  to  the  axilla.  These venae comites, or satellites,
are invariably called after  the arteries which they attend,
and having no difference from the  latter in relative situa-
tion, a further description of  them may be dispensed with.

  The Superficial Veins lie between the skin and the bra-
chial aponeurosis; and are considerably larger than the pre-
ceding.  Their  earliest roots are seen on the backs of the
fingers; they then appear on  the back of the  hand, on the
posterior face of the lower end of each  interosseous space.
There  are commonly six trunks in all; the one on the ulnar
side of the hand, and the three next to it, converge towards
the middle of the back of the carpus into a single trunk; the
two others, one of  which  comes from the thumb and the
other from the back of the fore-finger, converge to the outer
end of the carpus, and there form a single trunk also. Be-
tween  these several trunks  there are frequent anastomoses,
and they finally assemble into two principal branches called
the Cephalic and the Basilic Vein. 
VEINS OF THE UPPER EXTREMIT1 -
259
  The Cephalic Vein (Vena Cephalica, Radialis Cutanea)
is the trunk which comes from the thumb and from the fore-
finger, and has at first the name of Cephalica Pollicis.   It
ranges along the anterior and radial margin of the fore-arm,
and receives, continually, an augmentation from small col-
lateral branches  on  the  back of  the fore-arm.   Having
reached the bend of  the arm, it then ascends along the ex-
ternal margin  of  the biceps flexor cubiti till it reaches the
lower margin  of  the pectoralis major muscle; it then rises
superficially along the interstice between this muscle and
the deltoides,  to within eight or  ten  lines of the clavicle,
where it  dips down to join the axillary vein.  Along the
arm, it receives some small  secondary cutaneous branches.

   The Basilic Vein (Vena Basilica, Cubitalis Cutanea) is
larger than the cephalic, and begins by the trunk which
comes from the  ulnar side of the  back of the hand,  and is
first called the Vena Salvatella. On the fore-arm, the basilic
frequently consists in two long trunks, the anterior and the
posterior:  in this case, the  posterior is the principal one,
and runs along the internal posterior edge of the ulna until
it  comes to the bend of the arm; it then  mounts over the
latter, rising  obliquely in front  of the internal  condyle.
The anterior branch begins near the palm of the hand, runs
up in front of the ulnar side of the fore-arm, and discharges
itself into the  median basilic vein, over the brachial  artery
in front of the bend of the arm.  These two trunks, or one
as the case may be, receive  the cutaneous veins belonging
to the ulnar side  of the fore-arm.
   Above  the  elbow joint, the basilic gets below the fascia
of the arm at the inner edge of the  biceps, and about the
middle of the arm becomes, by its junction with the venae
satellites,  the Brachial Vein; but sometimes, as mentioned,
this junction occurs much higher up.

   The Median Vein (Vena Mediand) arises, by branches,
from  the wrist, from the palm of the hand, and from the
middle of the front of the fore-arm. It forms a trunk which 
260
CIRCULATORY" SYSTEM.
ascends in front  of the radial half of the fore-arm, and
which, a few inches below the bend  of  the arm, divides
into two.  One branch runs outwardly, in  ascending, for an
inch or two, and joins, at the outer side of the bend of the
arm, the cephalic vein; it is called, therefore, the Median
Cephalic.  The other branch continues to ascend, and cross-
ing obliquely the direction of the  brachial artery, it re-
ceives, near the latter, the anterior trunk of the basilic vein,
and somewhat  above the bend of the arm, runs into the
proper basilic vein; it is called the Median Basilic.
  There is frequently a departure from the preceding ar-
rangement of the median  vein; the most common is where
a trunk begins from the cephalic, below the  bend of the
arm, and runs up obliquely in front of the latter to join the
main trunk of the basilic above the elbow joint.  This ob-
lique trunk stands in the place of median  cephalic and me-
dian basilic, and receives  successively the median,  the an-
terior, and  the posterior basilic. It is frequently the median
itself, and has a short  anastomosis, in such case, with the
cephalic vein.

  The Superficial Veins anastomose frequently with each
other, so that, when they are all fully injected, a plexus of
veins is found  immediately beneath the skin of the upper
extremity from one end to the other. The Venae Satellites
also anastomose frequently by branches which cross the ar-
tery to which they belong.  At the bend of the arm, at the
wrist, and in  different places there are also anastomoses be-
tween the deep-seated and the superficial veins.

  The Axillary Vein (Vena  Axillaris)' results  from the
union of the basilic with the brachial vein. It is below and
in front of the  axillary artery, being included in the same
sheath with it, and also involved with the  axillary plexus of
nerves.   It retains its name from the lower margin of the
arm-pit to  the under surface of the clavicle, where like the
artery, it  is then  called subclavian.   In  this  course  it is
joined near the points where the corresponding arteries are 
VEINS OF THE LOWER EXTREMITY.
2 hi
given off, by the Anterior and the Posterior Circumflex
Veins; by the Scapular; and by the External Thoracic.

  The Subclavian Vein (Vena Subclavia) extends from the
termination of the axillary to the vena innominata, where
the latter is constituted by the junction of the internal jugu-
lar with  the subclavian.  In its course it  goes under the
subclavius  muscle,  and is in front of the subclavian artery
from the beginning, but near it; afterwards it is separated
from  the artery by the latter going between the anterior
and the middle scalenus muscle, whereas the vein runs over
the anterior end of the first rib,  in front of the insertion of
the scalenus anticus.
  The Subclavian Vein is joined by some branches coming
from  the shoulder and from the lower part of the neck, and,
at the outer margin of the origin of the sterno-mastoid mus-
cle:  it is augmented  by the addition  to it of the external
jugular.   It terminates at the internal margin of the scale-
nus anticus, as mentioned in the vena innominata.

      SECT. III.--VEINS OF THE  LOWER EXTREMITY.

  The veins of the lower extremity, like those of the upper,
are deep-seated  and  superficial.   The former  follow the
course of the arteries,  and are the venae satellites; there be-
ing, for the most part, two veins for every artery as far up
as the ham, and also as regards the muscular branches of
the thigh.   These venae satellites adhere closely to the ar-
tery, and are separated from each other by the latter. They
also have frequent anastomoses with each other across the
artery.

  The Popliteal Vein (Vena Poplitea) is  a single trunk
formed by the union of the anterior, the posterior tibial, and
the fibular veins.  It begins on the posterior part of the head
of the tibia,  and  extends  upwards through the ham to the
perforation in the adductor magnus muscle, which transmits
the femoral artery.   It is situated on the posterior face of 
262              CIRCULATORY SYSTEM.
the popliteal artery, to which  it closely adheres, and be-
hind it, is the popliteal nerve, the continuation of the great
sciatic.

  The Femoral Vein (Vena Femoralis) is the continuation
upwards of the popliteal;  it at first is placed behind the ar-
tery,  but in  a  short space it gets to its interior  face, and
continues to adhere to  it,  in that  situation, up to Poupart's
ligament, where it becomes the external iliac vein.  At the
usual  distance below the groin, where the arteria profunda
is given off, the femoral vein receives the vena cruralis pro-
funda, which is derived from  the branches of this artery,
and is rather more superficial than it; the two however ad-
here closely together.  Just  below  Poupart's ligament the
femoral vein receives  several small  branches of veins cor-
responding with the external pudic arteries.

  The Small Saphena (Vena Saphena  Minor Externa)
commences by several small branches near the external side
of the top of the foot, and the external  ankle;  a trunk is
formed by them behind the latter, which ascends along the
tendo-achillis and the  posterior face of the gastrocnemius
muscle, collecting several small veins from the back of the
leg in its course. This vein is superficial in its whole course,
being placed  immediately beneath the  skin.   In the ham,
it goes  for a short distance  along the internal face of the
popliteal nerve, and then makes a dip  through the adipose
matter there to empty  into the popliteal vein.
  It is  said,  by Portal, that  the  branches of this vein be-
come  very apparent in persons who suffer from podagra,
and from enlargements of the lymphatic glands in the ham.
In such case  their distention has been relieved by the ap-
plication of leeches along them.

  The Great Saphena (Vena Saphena Magna Interna) is
also superficial, has its  primitive roots  coming from the in-
ternal upper part of the foot, and from the sole of the latter.
These branches are assembled into a trunk which passes up- 
VEINS OF THE ABDOMEN.
263
wards in front of the internal ankle, then ascends along the
internal  face of the leg, in a line corresponding with the
posterior margin of the tibia.  The great saphena continues
its ascent over the  internal condyle near its posterior part,
and then mounts up the internal face of the thigh, in a line
corresponding nearly with the  internal  margin of the sar-
torius  muscle.   It finally terminates  in the  femoral  vein
about twelve or eighteen  lines below Poupart's ligament,
an opening being left in the fascia femoris for this purpose.
   In the whole of  this course the great  saphena is situated
between the skin and the fascia of the lower extremity; it is
consequently so superficial that in persons of moderate cor-
pulency it is very visible, and by slight pressure above,
along with the erect position, it becomes so much swollen,
that it is easily  opened  with the lancet where it passes over
the internal ankle.  It receives, in its ascent, small branches
from the anterior  and posterior part of the leg,  from the
corresponding surfaces of the thigh, and near its termination
it gets a few of the external pudendal veins.
   When the great  and  the small saphena veins are success-
fully injected, their branches are seen to  form a considerable
number of anastomoses, which thereby produce a remark-
able venous network, just beneath the skin of the whole
inferior extremity.


           SECT. IV.--VEINS OF THE  ABDOMEN.

   The  External Iliac Vein (Vena Iliaca Externa) being
the continuation of the femoral vein, passes into the abdo-
men, under Poupart's ligament, and in contact with the in-
ternal margin of the external iliac artery.  It there receives
the epigastric, and  the circumflex iliac veins, corresponding
with the arteries of the same name; it also receives a vein
of some size, which enters by the abdominal canal in ad-
hering to the spermatic chord, and which comes  from the
coats of the testicles.*  It keeps  then  along the  internal
side of the artery, somewhat behind it at the superior mar-
                 * H. Cloquet.  Traitfc" D'Anat. 
264
CIRCULATORY SYSTEM.
gin of the pelvis; and joins the hypogastric vein opposite to
the sacro-iliac junction, and thereby forms the common iliac
vein.

   The Hypogastric Vein (Vena Hypogastrica, Iliaca In-
terna) comes from the inferior part of the pelvis in front of
the sacro-iliac junction, and in company  with the hypogas-
tric artery.   It arises by branches  corresponding with the
distribution of the latter to the viscera of the pelvis, and to
its external parts; these branches are so numerous at parti-
cular points and  have such frequent anastomoses that they
are often named Plexus.  Thus  there is a hemorrhoidal
plexus for the lower part of the rectum, a  vesical for the
bladder,  a sacral for the sacrum, a pudendal for the parts of
generation in the male;  and a vaginal for the vagina, and
a uterine for the uterus of the female.
   The Plexus Hemorrhoidalis,  besides   being  connected
with the  hypogastric, also  anastomoses with the vena por-
tarum.
   The Plexus Vesicalis  is different in  the two sexes.  In
man it commences at the extremity of the penis  by several
branches, which unite into  two trunks of considerable size,
the Venae Dorsales Penis.  The latter go along the  upper
face of the penis, near or at its middle, to the symphysis of
the pubes, continually receiving in this course small trunks
from the integuments of the penis  and from the scrotum.
They then  get into the pelvis between the root of the penis
and the symphysis pubis, and continue horizontally  back-
wards on the side of the prostate gland, of the vesiculae se-
minales,  and of the lower fundus  of the bladder.   They
receive many branches from these  parts, which, with the
frequency of the anastomoses about  here,  constitute the
vesical plexus.  The latter finally discharges  into the  lower
part of the hypogastric vein by two or more branches.
   In the female the vesical plexus begins on the  dorsum of
the clitoris, by several branches  coming  from it and from
the vulva, they get into  the pelvis under the  symphysis
pubis and on the sides of  the urethra and of the vagina, 
VEINS OF THE ABDOMEN.
265
forming upon the lower part of the bladder, and on the side
of the vagina, with  the  assistance of branches from these
viscera, a remarkable plexus, which also empties into the
internal iliac vein.
  The Plexus Sacralis consists in an order of veins anasto-
mosing freely with each other, and corresponding with the
middle and the  lateral  sacral veins.  They communicate
with the inferior end of the vertebral sinuses through the
anterior sacral foramina; they also  communicate with the
hemorrhoidal and with the vesical veins.  They terminate
in the venous trunks nearest the origin of the arteries from
which they are derived.
   The Plexus Pudendalis is  derived  from the branches of
the internal pudic vein which go to the perineum, to the
posterior part of the scrotum, and to the integuments of the
under part of the  penis.  The trunk  formed by the  as-
sembling of these several ramifications, follows the course
of the artery to which  it belongs, and  gets  into the pelvis
at the lower part of the sciatic foramen, where it contributes
to the formation  of the hypogastric vein.
   The Plexus Uterinus consists in a considerable number
of veins, which are  distributed upon the surface, and in the
 texture of the uterus; they are also found in abundance in
 the broad ligaments, where  they anastomose with the ova-
 rian veins.
   The Plexus Vaginalis conies from the anterior parts of
 the organs of generation constituting the vulva, as the labia
 majora, minora,  and so on.   It also arises from the whole
 surface of the vagina, surrounds it completely, and anasto-
 moses with the uterine veins.
   The Gluteal, the Obturator, and  the Ilio-Lumbar Veins,
 also contribute to the Hypogastric; their description con-
 forms so nearly to that of the corresponding arteries, that
 it is unnecessary to detail it.

   The Primitive Iliac Vein; (Vena Iliaca Primitiva,Com-
 munis,) formed  by the junction of the External and of the
 Internal Iliacs, extends from  the  sacro-iliac symphysis to
   Vol. II—34 
466
CIRCULATORY SYSTEM-
the lower margin of the fourth lumbar vertebra on its right
side, where it joins the corresponding trunk of the opposite
side of the body, to form the commencement of the ascend-
ing vena cava.   In this course the left one passes obliquely
across the body of the  fifth lumbar vertebra, and beneath
the right primitive iliac artery.

   The Vena Cava Inferior  is situated on  the front of the
spinal column, to its right side, and extends from the lower
part of the fourth lumbar vertebra, or, in other words, from
the junction of the primitive iliac veins to the under end of
the right auricle of the heart, into which it empties.  It is
larger than the Descending  Cava.
   In its ascent it inclines very gradually to  the right side of
the spine, so as to  reach the  opening in the tendinous centre
of the Diaphragm, through  which it  passes, just before it
terminates in the auricle.  It is bounded on the left side by
the aorta; and above the latter it is in front of the left pillar
of the diaphragm.   Its lower extremity is crossed in  front
by the root of the primitive iliac artery; it is also crossed
in its ascent by the duodenum and the pancreas.   Its upper
extremity is behind the liver, and frequently passes through
the substance of this viscus.
   It receives the middle sacral, the lumbar, the  spermatic,
the emulgent, the capsular,  the  hepatic, and the phrenic
veins.

   The Middle Sacral Vein (Vena Sacra Media) forms, as
has been just mentioned in  the account of the branches of
the hypogastric vein, a part  of the sacral  plexus.   Its trunk
follows the course  of the middle sacral artery on the  front
of the sacrum,  and discharges into the commencement of
the vena cava, in the fork formed by  the origin of the pri-
mitive iliacs.

   The Lumbar Veins (Venae Lumbales) correspond with
the lumbar arteries, and are  commonly four or five in num-
ber on each side.   Their primitive roots anastomose with 
VEINS OF THE ABDOMEN.
267
 the epigastric, the last intercostal, and the circumflex iliac
 veins; the dorsal branches of them  also  anastomose with
 the vertebral sinuses, through the intervertebral foramina.
 Their trunks pass along with the arteries, between the bo-
 dies of  the  vertebrae and  the  psoas  magnus muscle,  or
 through  the  fasciculi of  the  latter; those  on  the  left side
 pass behind the aorta, in order to reach the vena cava, and
 are consequently longer  than such as are on the right.

   The Spermatic Veins  (Venae Spermaticae.)  The right
 one extends from the testicle, to the ascending cava just be-
 low the emulgent veins;  while  the  one on the left empties
 into the left emulgent vein.   They are larger than the cor-
 responding arteries,  and present some  peculiarities in the
 two sexes.
   In the male, the extremities of these veins  begin in the
 testicle,  and issue from  it through  the tunica albuginea;
 some of them also arise from the  epididymis.   They anas-
 tomose with  the  superficial veins of the  penis and of the
 scrotum, and disengaging themselves from the tunica vagi-
 nalis,  at its back part, are assembled into  four or five anas-
 tomosing  trunks, which  envelop the vas  deferens and the
 spermatic artery, and compose a principal part of the bulk
 of the chord.   Having passed  through the abdominal ca-
 nal, they are reduced  on each  side to one trunk, which
 creeps along the spermatic artery, on the front of me psoas
 magnus muscle,  and  in company with  the ureter.   Some-
 what below the kidney, the spermatic vein is again resolved
 into a sort of plexus,  having  frequent  additions from the
 veins in the adipose substance of the kidney, and also some
 from the branches of  the  vena portarum in the mesentery
 and in the mesocolon.  It then  is reduced once more into
a single trunk, which terminates as mentioned.   The term
Corpus Pampiniforme (vine-like)  is, by some anatomists,
limited to  the last plexus formed by each spermatic vein,
but it is also frequently extended to both* *
  In the female the spermatic vein is not so large as in the
* H. Cloquet, Trat D'Ana* 
268
CIRCULATORY SYSTEM.
male; it comes from the ovarium and from the  side of the
uterus,  and is joined  by some small branches from the
round ligament of the uterus, and from the Fallopian tube.
Passing outwardly between  the laminae of the  broad liga-
ment of the uterus, it crosses the external iliac  artery, and
in the subsequent part of its course is disposed of as in the
male.

  The Emulgent Veins (Venae Emulgentes, Renales') are
commonly two in number, one on each side, and extend ho-
rizontally from the fissure of the kidneys to the ascending
cava.  They are of a considerable size,  and owing to the
position of the vena cava, the left is much longer than the
right,  and crosses  in front of the aorta.  They open on
their respective sides of the cava  opposite to each other.
The branches of which the emulgent vein is composed,
coming from the ramifications  of the corresponding artery
in the kidney, assemble into the single trunk near the fissure
of the kidney, this  trunk is joined by some small  veins
from the adjacent adipose matter and from the capsulae re-
nales, and on the left side, as  mentioned, it is also  joined
by the spermatic vein.

   The Capsular Veins  (Venae Capsulares) arise from the
arteries spent  upon the capsular renales;  and  are two  in
number, one on each side.   That on  the right  discharges
into the vena cava,  while the  one on the left empties into
the left emulgent frequently.

   The Hepatic Veins (Venae Hepaticae) take their rise in
the  liver,  and collect  into  three  principal trunks, which
converging towards the ascending cava, discharge  them-
selves into it where it adheres to the posterior margin of the
liver, immediately below the  diaphragm.  Two of these
trunks come from  the  right lobe, and  one from the left;
moreover, there are several  small hepatic veins which dis-
charge themselves into the cava, and come principally from
the Lobulus4Spigelii. 
THE VENA PORTARUM.              269
  The Inferior Phrenic Veins  (Venae Phrenicae Inferio-
res) come from the diaphragm, from the corresponding ar-
teries. They are two in number, and discharge into the as-
cending cava just above the hepatic veins.


           SECT. V.--OF THE VENA PORTARUM.

  The Vena Portarum  is derived  from the viscera of the
abdomen, and presents the singularity of a vein ramifying
through a gland, the liver, before  its blood is returned to
the general circulation.  The  arteries from which it draws
its  supply of blood are the superior and the inferior mesen-
teric, and the coeliac with the exception of its hepatic branch.
The viscera of the abdomen, which contribute to it, are the
spleen, the  stomach,  the  gall-bladder, the pancreas, the
small intestines, the large and the small omentum.
   a.  The Splenic Vein ( Vena  Splenica) is formed by se-
veral branches,  which coming out distinctly from the fissure
of the spleen, unite after a short course into a single trunk.
This trunk runs in company with the splenic artery, below
it,  along  the  superior  margin of the pancreas, is not quite
so tortuous as the artery itself, and proceeding from left to
right, is joined to the  superior mesenteric vein in front of
the vertebral column.
   In this course the splenic receives the small veins* (Venae
Breves)  corresponding with  the vasa brevia of the  great
end of the stomach,  and then, successively, several branches
from the pancreas.   It likewise receives the gastric, or the
superior  coronary vein of the  stomach, the  right gastro-
epiploic,  and the left gastro-epiploic of the same viscus, all
of  which  correspond with the arteries distributed to the
latter.
   b.  The Inferior Mesenteric Vein (Vena Meseraica In-
ferior) corresponds  with the inferior mesenteric artery, and
consequently derives  its primitive branches from the rec-

  * M. Bauer discovered, in 1824, valves in these vessels, contrary to the
general analogy of the system of the Vena Portarum. His observations
have been confirmed by H. Cloquet. 
270
CIRCULATORY SYSTEM.
 turn by the upper  hemorrhoidal veins,  which anostomose
 with the lower; from the sigmoid flexure of the colon, and
 from the left descending  portion of the  latter.  The trunk
 formed by these branches, ascends behind the peritoneum,
 between the ureter and the aorta, and going up behind the
 pancreas, is discharged into the splenic vein an inch or two
 from its termination.  But like the veins belonging to the
 lesser curvature, and the  right side of the stomach, it some-
 times empties directly into the vena portarum, or into the
 upper end of the superior mesenteric.
   c. The Superior Mesenteric Vein (Vena Meseraica Su-
perior) is the largest of the trunks which contribute to form
 the vena portarum.  It is derived from the ramifications  of
 the superior mesenteric artery upon the small intestines, the
ileo-colic valve, the right ascending, and the transverse co-
lon.   Its branches constitute in the mesentery and the me-
 socolon a vascular intertexture,  forming  arches and meshes
adhering to the corresponding ones of the arteries.   In the
transverse mesocolon  it,  like the artery, anastomoses with
the inferior  mesenteric vein.   Its  trunk being formed by
the union of these  several branches, ascends the mesentery,
and goes in front of the duodenum, where the  latter crosses
the spine; immediately afterwards  it gets behind the pan-
creas and near its right end is joined by the  splenic vein.
It here, also, receives  small branches from the duodenum,
from the pylorus, and from the gall-bladder.

   The trunk of the vena Portarum  being formed behind
the pancreas by the union of the inferior mesenteric with
the splenic vein, extends from  this point to the transverse
fissure of the liver, and is about four inches in length.   It
ascends obliquely from left to right, behind the second cur-
vature of the duodenum,  being  bounded on the right side
by the biliary ducts, and on the left by the hepatic artery,
where  it is surrounded by a great many  nervous  filaments
and lymphatic vessels,  with all of which it is  united by a
common envelope of cellular substance, and of peritoneum,
called the capsule of Glisson.   Having reached the  trans- 
PECULIARITIES OF THE FQ5TUS.          271
verse fissure of the liver it divides into two branches, which
are each at a right angle to it, but in line with one another;
they  constitute the Sinus Portarum, of which, the right
branch  being spent upon the great lobe, and the left upon
the small lobe of the liver, are ramified to infinity through
the structure of the  latter.  The  terminating  branches of
the vena portarum empty into the venae hepaticae.

   Several cases are recorded in the annals  of  anatomy in
which  the vena portarum, instead of going into the liver,
discharged immediately into the ascending cava.*   In such
instances the hepatic artery is much larger than usual.  Ac-
cording to J. F.  Meckel, notwithstanding they are anoma-
lies, yet as in most other cases of  deviation from  the gene-
ral type of the human  family, a  striking analogy may be
found between them and what occurs in some of the lower
orders  of animals.   Here the analogy exists with the inver-
tebrated animals.
                     CHAPTER IV.

   OF THE PECULIARITIES IN THE CIRCULATORY SYSTEM
                     OF THE FOZTUS.

   Owing to the want of  respiration in the foetus, its circu-
lation is conducted in a manner very different  from that of
the adult.   Moreover, its parasitical life  requires an alli-
ance, through the organs of circulation, with  the  mother.
Its peculiarities, therefore, may be studied under two heads:
those which arise from the want of  respiration, and those
which are required for its nourishment.   The  peculiarities
of the first  order  are situated in the thorax,  and  those of
the second in the abdomen.

  * Lieutaud, Hist. Anat. Med.   F;uber, Obs. Anat. p. 34.  Abernethy,
Ph. Tr. 1793, part i.  Lawrence, Med. CI). Trans, vol. v. 
272
CIRCULATORY SYSTEM.
 SECT. I.--OP THE PECULIARITIES OP THE FOETUS ARISING
            FROM THE WANT OF RESPIRATION.

   The  Heart, at a very early period  after conception, so
early as about the end of the first month, is sufficiently de-
veloped to be in  a state of great activity.   The first indi-
cation of  its existence, and indeed of the  life of the  new
animal, is a small tremulous point called the Punctum Sa-
liens, from its incessant motion.   The  muscular structure
of it is soon evolved, and in a few months becomes very
manifest.   At the earliest visible period of the heart in the
incubated egg, which  affords a satisfactory analogy, it con-
sists of two vesicles  united  by a canal, (Canalis Auricula-
ris of Haller.)   0;e  of the vesicles is the right auricle;
the other  is the left ventricle,  and is probably the first to
pulsate.   The aorta is also visible, as well as the venae cavae.
The circulation,  at this period, is very simple; the blood
starting from the left ventricle is  propelled  into the aorta;
it  is collected from the ramifications of the last into the two
venae cavae, and thereby brought to the  right auricle;  it is
then propelled by the right auricle  through the canalis au-
ricularis into the left ventricle, whereby its round is com-
pleted, and then  starts again. This is the most simple kind
of circulation, and is found, in fact, during the whole lives
of such animals as  do not breathe by lungs, for example,
fish.  As the gills in them take the place of lungs, a branch
from the aorta, spent upon  the gills, is  sufficient for their
purposes of respiration.
   The terms right auricle and left ventricle have been used,
because the cavities alluded to perform the functions of the
adult state; but in the progress of the development of the
heart, a partition begins to show itself which ultimately di-
vides each of them into two distinct compartments, where-
by we have a right auricle  and a left one, a left ventricle
and a right one.    And the  canalis auricularis is  reduced
from a canal into a short orifice called ostium venosum, com-
municating from  the  auricles to the ventricles, and which 
PECULIARITIES OP THE FffiTUS.
273
 is afterwards divided into two, one for either side of the
 heart.   The partition between the  ventricles  is completed
 about the end of the second  month of gestation, at a period
 when the aorta, from having been simple originally, is con-
 verted into two canals, one of which becomes the pulmona-
 ry artery.  The partition between  the auricles is not com-
 pleted till birth.   In  cases of monstrosity, it is interesting
 to see how much the heart,  at the end of uterine life, has
 still preserved this original type of simplicity.   I have late-
 ly dissected a double foetus,  where,  from the parasitical cha-
 racter of one, no effort had been made for the development
 of the lungs of the latter.  The consequence of which was,
 the parasite's heart  consisted only of the  right auricle and
 of the left ventricle, and the pulmonary artery had not been
 formed  at all, there being but the single  tube, the  aorta;
 which led from the left ventricle, and had  a sort of arrange-
 ment in its branches depending upon the tendency to form
 pulmonary arteries.*
   At birth, the  auricular  septum has advanced  so far that
 the communication between  the cavities is kept up only by
 a deficiency called  the Foramen  Ovale.   This foramen,
 marked  by a depression on  the right side, admits a small
 quill when conducted obliquely through it, and is protected
 on the left side  by a valve, the edge of which is upwards,
 and which, when applied, is just large enough to cover the
 whole foramen.   The moment that the blood ceases to pass
 through  the foramen ovale,  which occurs  at the first act of
 inspiration, the valve is applied, and the aperture grows up
 by the adhesion of its edge.   The mechanism of this pro-
 cess is sufficiently simple.  So long  as the  principal current
 of blood was into the right  auricle, the valve was pushed
 off from the side of the  septum;  but as  breathing esta-
 blishes, through  the lungs,  pulmonary veins,  and left au-
 ricle, a  current  of  circulation  equivalent,  both  in quan-
 tity and  force, to that .through  the two  venae  cavae and
 right  auricle; a  perfect equilibrium  between  the auricles

  * For a detail of this case, see North American Medical and Surgical
Journal, Philad. Oct.  1826.
  Vol.  II.—35 
274
CIRCULATORY SYSTEM.
is  established, and the valve retains its  place  against  the
septum.   Notwithstanding the incessant action of the auri-
cles  during all  the subsequent periods of life, this equili-
brium, in the force and time of their contraction, is never
departed from.  A circumstance proved conclusively by the
health and strength of adults in whom the valve has never
adhered to the day of their death;  an observation made by
many  anatomists, and of which I  have witnessed several
examples; in one of them I passed two fingers readily from
one auricle into the other, owing to the  unusual size of the
aperture.
   The valve which closes the foramen ovale is, first of all,
scarcely perceptible; but as the foetus advances in age, it
also advances in size, and is, indeed, large enough to close
the foramen some weeks  before birth.   It is formed from
the lining membrane of the two auricles with some inter-
mediate substance.

   The Valve of Eustachius, which exists also in  the adult
heart, is placed at  the anterior  semi-circumference of the
orifice of the ascending vena cava in the right auricle, one
of its ends adhering to the anterior margin of the foramen
ovale.  This  valve,  contrary to the one in the foramen
ovale, is larger  in proportion  as the foetus is younger, and,
when first observed, covers the whole  orifice of the vena
cava ascendens; its opening, however, is in the direction of
the  current of blood in the latter.   It also is formed by a
duplicature of the lining membrane of the auricle, and,  from
its disposition, determines the blood of  the ascending cava
to flow through the foramen ovale  into the left auricle, ei-
ther wholly or in part, according to the period of gestation.
Its obliquity  also gives a direction to the blood of the de-
scending cava, into the right ventricle from  the  right au-
ricle.   These uses of the Eustachian valve  were pointed
 out by the celebrated Sabatier;* their value will  be  illus-
 trated hereafter.

   The Ventricles of the Heart, at birth, have the  same
' Traite d'Anat. vol. ii. p. 296. 
             PECULIARITIES OF THE FC3TUS.          275

structure and internal arrangement as afterwards;  they are
remarkable, however, for being of equal thickness, or nearly
so, an observation of Mr. John Hunter.* This fact is con-
nected with the circumstance of their  both  contributing to
the aortic circulation till respiration begins, owing to the
pulmonary artery entering, during foetal life, by its  largest
branch, into the aorta.

   The Ductus Arteriosus constitutes this branch of the pul-
monary artery, and is, in fact, the continuation of the trunk
of the latter into the aorta, immediately behind the origin
of the left subclavian artery. The right and the left pulmo-
nary arteries, at this period, are but inconsiderable trunks,
incapable by any means of carrying off all the blood of the
right ventricle; the greater part of it therefore is conveyed
by the ductus arteriosus into the descending aorta.  As the
contraction of the ventricles, like that of the  auricles, is
synchronous, it is evident that the column  of blood in the
descending aorta, is  acted upon by both ventricles at the
same moment.
   The  ductus  arteriosus, preserves the principle  of a sin-
gle  circulation  in the  foetus;  which was first of  all mani-
fested by the two ventricles, constituting but one  cavity;
and  by the aorta and pulmonary artery  being but one
trunk.  At the first act of inspiration the lungs, which were
before solid, and the thorax, which was compressed, are
greatly augmented in  volume by the introduction of air.
The dilatation of the thorax, besides introducing air through
the trachea, causes an  increased  flow of blood through the
right and left  pulmonary  arteries, in  order to  fill  the va-
cuum in the lungs.  The pulmonary arteries become in that
way  permanently dilated,  and the circulation  is  finally
drawn off entirely from the ductus arteriosus, though this
takes several weeks or months before it is completely ac-
complished.  The ductus  arteriosus in  this time is conti-
nually contracting, and is  at  length converted into a liga-
* Animal fficonomy. 
276
CIRCULATORY SYSTEM.
mentous chord, like other  arteries, whose circulation has
been arrested.

  These are the several  peculiarities which distinguish the
foetal circulation, owing to the privation of respiration; and
it is clear, that the collective result is that of a circulation
quite as simple as if the heart consisted of but two cavities;
while, at the  same time, it keeps this organ in a state of
preparation  for carrying on two distinct circulations, one
pulmonary and the other aortic, from the moment that re-
spiration begins; so that the whole mass of blood is, in sub-
sequent  life,  brought  successively under the influence of
respiration, by having  to  pass unavoidably through the
lungs.


SECT. II.--OF THE PECULIARITIES OP THE CIRCULATION OF
     THE FOETUS CONNECTED WITH ITS NOURISHMENT.

  The Umbilical Vein, one of the constituents of the umbi-
lical chord,  brings the  blood from the placenta to the foetus.
This vessel is from three to four lines in diameter, and enters
at the navel;  thence it  goes along the loose margin of the
suspensory ligament of the liver, and traverses the anterior
half of the umbilical fissure, to terminate in the left branch
of the sinus of the vena portarum.  In this course through
the liver, the umbilical  vein sends off to the right and left
lobes, several small branches.  As the  intestinal circulation
of the foetus is too small to send much blood through the
vena portarum, it would be sufficiently correct to consider
the sinus venae portarum as the bifurcation of the umbilical
vein, but, as  this might introduce a confusion into the de-
scription, it will be better to retain the adult nomenclature.

   The Ductus Venosus is a vein which occupies the poste-
rior half of the umbilical fissure, and  is about a line and a
half in diameter.  It arises from  the left branch of the sinus
portarum, opposite to the  place where the umbilical  vein
 entered or terminated, and is consequently in the same line 
CIRCULATION OF THE FffiTUS.          277
with the latter. Traversing the posterior part of the umbili-
cal fissure, it terminates in the left vena cava hepatica, as
this vein is about joining the ascending cava, just below the
tendinous centre of the diaphragm.  Through this rout much
of the blood of the umbilical vein is carried directly to the
right auricle of the heart, and then passed through the fora-
men ovale into the left auricle  by the mechanism of the
Eustachian valve.

   From these considerations, it  is evident that the umbili-
cal vein really performs the office of a vein  till it reaches
the liver, but that there much of its blood is spent through
the portal circulation, upon the nourishment of this viscus,
and that what remains is carried  through the ductus venosus
to the heart.  Like other veins, it is furnished with valves,
of which there are two: one  at its termination in the sinus
portarum, and the other  at the cardiac extremity of the
ductus  venosus.*  The establishment of  respiration,  by
putting the circulation  into other channels, likewise causes
its obliteration and final conversion into a ligamentous chord.
The valve,  at the sinus portarum, prevents the blood from
taking  a retrograde  course, and thereby keeping the um-
bilical vein open;  the  valve of the ductus venosus has the
same effect upon the  duct  to which it belongs, and is aided
by the current of blood in the left sinus portarum, setting
across the mouth of the ductus venosus instead of plunging
into it from the umbilical  vein, as in foetal life.
   It is worthy of remark, that the left branch of the sinus
portarum is bounded, on its right extremity,  by the end of
the vena portarum, and receives, about its middle, the um-
bilical vein.  In the space,  then, between the umbilical vein
and the portal, the circulation,  from the predominance of
umbilical blood in foetal life, is conducted from left to right,
but afterwards from right to left, as the portal circulation is
established and the other is arrested.

   The Umbilical Arteries discharge the important office of
conducting  the effete blood of the foetus to  the  placenta.
*  Bichat, Anat. Descrip. vol. v. p. 419. 
278
CIRCULATORY' SYSTEM.
 They are the continuations of the  internal iliacs, and arc
 two in number, one  on either side; they conduct off so
 much of the blood of the primitive iliacs, as to leave the
 external iliacs of a very small size.  During the early months
 of uterine life, they are rather indeed the continued trunks
 of the primitive iliacs, the branches from  the latter being
 then  so little developed  as to appear quite subordinate to
 the chief function of carrying  the blood out of the foetus to
 the placenta.   But as  the inferior extremities and the but-
 tocks grow, these subordinate  branches are more and more
 evolved.
   At birth, the umbilical arteries,  after dipping very su-
 perficially into the pelvis, rise up at the sides of the bladder
 and converge towards the navel.  They emerge at the latter,
 cling together and traverse  the umbilical chord by twisting
 spirally around  the  umbilical vein,  like two small  strings
 wound  in this way  upon a  larger one.  Their diameter is
 from a line to a line and a half.  They anastomose as they
join the placenta, but not previously.
  Like the circulation between arteries and veins in other
 parts  of the body, the capillaries of the  umbilical arteries
 terminate in those of the umbilical vein in the placenta.
 From  the  observations of  Wrisberg, Osiander, and the
 highly distinguished Professor Chapman of the University
 of Pennsylvania, it seems that there is  no direct vascular
 communication between the mother and  the foetus.
  This opinion is founded upon the leading facts, that the
 finest injections  do not pass from one to the other; that foe-
 tuses, after the death of the mother from haemorrhage, still
live and retain  their usual quantity of  blood; that if the
foetus be expelled entire with the placenta, and membranes
unhurt,  the circulation still continues.   One example  of
which was witnessed nine minutes by Wrisberg;* another
fifteen by Osiander ;t  some  from ten to twenty minutes
by Professor Chapman;J  another for an  hour by Professor
Channing of Boston, and  Dr. Selby of Tenness'e,§ where
a bath of tepid water was used to resuscitate the foetus. Also,
  * Meckel, Man. D'Anat. vol. iii.  p. 163.           f Id.
  v Chapman's Med. and Phys. Journal, vol. i. p. C\    & T<< 
CIRCULATION OF THE FOETUS.          279
from  the  observations of Breschet, it  seems that the  glo-
bules of the blood of the foetus, when inspected by the mi-
croscope,  are  different in appearance from those of the mo-
ther.*
   The effete blood of the umbilical arteries becomes rege-
nerated in the placenta, assumes  a brighter hue, and is re-
turned  to  the foetus by the  umbilical vein.  According to
the theory of Sabatier concerning the  use of the Eustachi-
an valve, if the latter did not exist, the fresh blood brought
to the heart by the ductus venosus, instead of being divert-
ed into the left auricle through the foramen ovale, would be
received  by the right auricle and  transmitted, either wholly
or in a great degree, into the right ventricle.  It would then
be passed from  the latter through the pulmonary artery and
ductus arteriosus into the descending aorta, so that no part of
the system,  above the junction of the duct with the aorta,
could receive the benefit of it: this would leave  the  head
and upper extremities unsupplied with fresh blood.  More-
over, much of the  latter would be fruitlessly introduced,
for it would depart almost immediately through the um-
bilical  arteries.  But the Eustachian valve determining the
 flow of blood of the ascending cava into the left auricle, its
 passage into  the left ventricle is  a matter of course; thence
 it begins the aortic circulation fairly,  so that every part of
 the system participates in its benefits.
   The celebrated Wistart has also happily suggested, that
 without this  arrangement the blood of the coronary arteries
 of the  heart itself, the purity of which is so essential to the
 vigour of circulation, would otherwise have been effete, and
 consequently unfit  for its object of refreshing the heart. *

   The umbilical arteries become the round ligaments of the
 bladder,  after the circulation through them has ceased, with
 the exception of their pelvic extremities, which subsequent-
 ly constitute the trunks of  the Internal Iliac Arteries.

           * Am. Med. Jour. vol. i. p. 193.
           I System of Anat. vol. ii. p. 76, 3d edition. 
280
CIRCULATORY SYSTEM.
                     CHAPTER  V.

 OF THE GENERAL ANATOMY OF THE ABSORBENT SYSTEM.

   The absorbent system  is one of the most interesting of
 those which compose the human body, both on account of
 its very general diffusion, and of the office of interstitial
 absorption that it incessantly carries on,  thereby removing
 the effete parts of the body and making room for the depo-
 site of  new ones.  It is also called the  lymphatic system,
 owing to the transparent  colour of the fluid which it con-
 ducts.
   With the exception of an imperfect observation of some
 of these vessels in the mesentery of a goat, by Herophilus
 and Erasistratus, 280 years before Christ, during the reigns
 of the Ptolemies in  Egypt, what  is  known of them is en-
 tirely a modern acquisition in anatomy.   In 1564, Eusta-
 chius discovered the thoracic duct of a horse, which, in the
 ignorance of its use,  he called vena alba  thoracis.   This
 fact  remained  insulated  and almost  forgotten for seventy
 years.   In 1622, Asellius discovered the absorbents of the
 mesentery, and in the discussions  consequent thereto, the
 original observation  of  Herophilus and Erasistratus  was
 raised  from an oblivion of nineteen centuries, to be again
 brought to light and admired.   Asellius seems to have un-
 derstood that the absorbents of the  mesentery collect the
 chyle from the intestines,  but his knowledge ceased there,
for he thought that they discharged  into the vena porta-
rum.*   In 1634, Weslingius saw  the thoracic duct again;
and in  1649,  ascertained  that  the chyliferous  vessels of
 Asellius terminated  in  it.  In 1650, Olaus  Rudbeck,  a
young man pursuing his  anatomical studies in Leyden, saw

  * It is somewhat remarkable, that the celebrated Harvey, who had him-
self so much to complain of, in the obstinacy with which his cotempora-
ries adhered to ancient errors, for thirty years resisted the discovery of
Asellius, and died finally pro*esting against it 
           ANATOMY OF THE ABSORBENT SYSTEM.       281

 first the lymphatic vessels of the liver, and in a few months
 afterwards injected similar ones in the loins, in the thorax,
 in the groins, and in the  arm-pits.  Thomas  Bartholine, a
 teacher of great reputation in those days, in a dissertation
 dated in 1652, claimed for himself the priority of these ob-
 servations, and from the  obscurity of Rudbeck, enjoyed for
 some time the merit of them.  In 1654,  Rudbeck published
 and set forth his own  pretensions with  such  force, that he
 finally  triumphed  over  his antagonist, but not until the
 whole  world  of anatomy had been set in  commotion;
 one party being for the professor, and the other for the pu-
 pil; and many bloody  strifes having arisen between the stu-
 dents of the  respective sides.  In 1653, Jolyff, a celebrated
 anatomist, of London, proclaimed  his  own  rights to this
 warmly contested honour, but the period  being rather late,
 his  name  is scarcely  associated with the history of  these
 feuds.   Almost a  century then passed before there  were
 many important additions to the knowledge of those times.
 After  which great contributions were made by  Dr. A.
 Munro,* Dr. W.  Hunter,t Hewson,J  Cruikshank,§ but
 chiefly  by the celebrated Mascagni, || who having imagined
 finely pointed instruments of glass for  executing his injec-
 tions of these vessels, succeeded in demonstrating them in
 almost  every part of the body,  excepting the spinal  mar-
 row, the brain, the ball of the eye, and the placenta.

   The Lymphatic Vessels are small, pellucid, transparent,
 cylindrical tubes, generally of about a  line or less in dia-
meter, whose trunks have been traced  to all the  external
and internal  surfaces of the  body, and to the depth of all
the organs,  with the  exceptions stated.   It is only very
lately,  however, that their existence on the external surface
of the skin has been put beyond doubt, by the  observations

  • De Venis Lymph. Valv. Berlin, 1757—70.
  f Med. Comment. London, 1762—77.
  t Experimental Inquiries,  London, 1774—77
  § Anat. of the Lymphatics, London, 1774—90.
   Vasor Lymph. Corp. Hum. Historia et Ichnographia, Sienne, 1787.
  Vol.  II.--36 
282
CIRCULATORY SYSTEM.
and injections of M. Lauth.*   Their origin is so attenuated,
that anatomists have come to  no satisfactory conclusion in
regard to its  manner. The earlier cultivators of this branch
of study, not knowing their absorbent properties, conceived
them  to be continuations of the arteries applied to the re-
conducting of the serous part of the blood to the heart; and
considered the opinion substantiated by the circumstance of
their  being occasionally filled by fine injections thrown into
the arteries.    More improved views of their uses caused
the abandonment  of this theory, and  the substitution  of
their  absorbing powers;  in which case the minds of anato-
mists became divided between the ampulla-like mouth,  or
wide patulous origin of Lieberkuhn, and the small orifices
of Hewson.   It is, perhaps,  not possible to solve the ques-
tion in regard  to the mode of origin of the lymphatics, at
least  in most parts of the body.  Meckel,  about the middle
of the last century, asserted their continuity with the veins.
Mr. Ribes has seen matter injected into the vena portarum
find its way into the lymphatics of the liver.
   On this subject M. Chaussier  says,t that, ignorant of
the  manner  in which  the  arteries,  veins, nerves, and
lymphatics, arrange themselves  collectively into a glandu-
lar structure, or,  in other words, into a capillary system,
we cannot avoid  ignorance of the  part acted by the lym-
phatics alone; we only  know that the minute  lymphatics
form a portion of  the elements of each viscus and structure
of the body, and that they only become visible in becoming
larger trunks.
   The absorbents, in proceeding from their origins, in  ge-
 neral become larger and  less  numerous, and  form frequent
anastomoses with one another.   The proportionate increase
of magnitude from the successive junction of trunks is, how-
 ever, by  no  means equal to what occurs in the veins.   The
 larger superficial absorbent trunks of the extremities have
 not so much  disposition  to run into  one another, whence
 they retain a size almost uniform from one end of  the limb

   * Essai sur les Vaisseaux Lymph. Strasburg, 1824.
   ■»■ Diet, de* Sciences Med. Art. Lymphatics. 
          ANATOMY OF THE ABSORBENT SYSTEM.       283

to the other.   When fully distended, the appearance of ab-
sorbents is not regularly cylindrical, but knotted, owing to
the frequent valvular interruptions to their cavities.   The
absorbents, from all parts of the body, are finally united
into two trunks; one on the left, and the other on the right
side of the trunk of the body, and which  discharge their
contents into the venous system, each on its respective side,
at the  junction of the internal jugular and subclavian vein.
The trunk on the right side receives the lymphatics of the
right side of the head  and neck, of the right  lung, and
right superior extremity; while the trunk on the left, called
the thoracic  duct, receives all  the chyliferous vessels and
the lymphatics of the remaining part of the body.  It would
appear, from  the observations of  the younger  Lauth,* that
there are also other  terminations of the lymphatics in the
veins; to wit, such  as in the  yet capillary state end in the
veins of the minute structure of organs, and such as empty
into them in  the interior of  the lymphatic  glands.  Pre-
viously  to Lauth,  this sentiment of communication  with
the veins was strongly advocated by several anatomists and
physiologists, for the following reasons: 1. That the known
roots of the lymphatic system  have an area much superior
to that of the trunks  in  which  they terminate.   2.  That
 substances introduced into certain lymphatics by absorption
or injection,  have been found  in the contiguous veins.  3.
 That a ligature upon the thoracic duct only produced death
after ten or fifteen  days, and  then the articles which had
been absorbed by the intestines,  were found in the blood.
4. And that  injections had proved this communication.
   Notwithstanding the well known fact of injections, under
certain  circumstances,  passing from  the  arteries into the
lymphatics, anatomists of modern date have always hesitated
in admitting  a direct communication.  M. Meckel has in-
deed rejected the notion entirely, on the  ground that the
fluid contained  in  the  trunks of  the absorbents, is  always
the same as one finds at their commencement.  For exam-
 ple, the lymphatics  coming from the liver contain a fluid
* Loc. cit. 
284
CIRCULATORY SYSTEM.
like bile; those which come from  the mammae  contain a
fluid like milk;  those which come from parts suffering from
an extravasation of blood, contain a sanguineous  fluid;  the
bronchial glands are coloured by the black pigment brought
to them from the lungs; poisonous matter, as that of  the
small-pox or venereal, irritates and inflames the lymphatics
that lie  in the course of its introduction into the system.
For these reasons it would appear, that the arteries  do  not
continue themselves into the lymphatics as they do into  the
veins; yet the  observations of M. Lauth seem to have
proved the point, that some of the  lymphatics take their
origin from the internal surface of the arteries, and that it
is probably through them that  injections have  been  forced
from one system into the other.
  The coats of the lymphatics generally are too thin and
transparent for an investigation of their structure;  but as
those of the thoracic duct are sufficiently large for the pur-
pose, one may estimate the structure of other trunks by it.
It is thus ascertained that they consist of two coats,  an  in-
external and an ternal one.
  The external coat  is somewhat irregular in  its surface,
from its connexion with the adjacent cellular substance; and
has a filamentous appearance more deeply,  which has been
considered as fibrous, or  muscular by some  anatomists,
owing to its contraction upon the application of certain sti-
mulants.  The internal  membrane is  extremely  fine and
perfectly transparent, and is remarkable for its frequent du-
plications, whereby a system of valves is produced resem-
bling those of the veins.   These valves are generally of a
semilunar or parabolic shape, and are arranged  in  pairs,
though according to Lauth,* some of them are circular, and
do not close the  canal entirely.  The pairs are not placed
at stated distances from one another, but vary  in different
parts of the body; in some places there are several  in the
course of an inch, and in others not one  pair.  As a gene-
ral rule, they are less frequent as the trunk increases  in
magnitude; hence  the  thoracic  duct has but very few  of
* Loc cir 
ANATOMY OF THE ABSORBENT SYSTEM.       285
them.    The  valves,  by  having their semicircumference
fixed, while the diameter  is loose and inclined in the course
of the circulation,  prevent the retrograde movement of the
contained  fluid.   The enlargement of  the  trunk  at  their
cuter face into sinuses resembling those at the valves of the
reins, gives also to the lymphatic trunk the knotted condi-
tion when  it is fully injected.
  The  coats  of  the  lymphatic  vessels, though very thin,
are yet dense and extremely strong, much more in propor-
tion than those of any other tubes.  They  are  both exten-
sible and elastic, possess striking powers of spontaneous con-
traction in the living body, and also in the dead, but to a
less extent.   They are furnished with arteries and  veins,
and probably with nerves also, from  their sensibility in a
state of inflammation.   And as they stand in need of a si-
milar organization with other canals, their parietes are said*
also to  have lymphatics.
  The  absorbent vessels are by some divided  into lacteals
and lymphatics,* the first term expressing those which con-
vey the chyle from the intestines, and the second such  as
are found in other parts of  the system.   As  the difference
is more in the fluid conducted  than in  the  structure  of the
vessels themselves, the division is rather superfluous.  There
is also  a distinction of the lymphatics, arising from their
situation, as in the veins;  some  of  them  are called superfi-
cial, and the  others  deep seated.   The  arrangement upon
which  this nomenclature depends, is  found  in the  head,
trunk,  extremities, and in  the  most of the viscera.   The
deep seated  trunks  are  the largest, but the least  nume-
rous.

  *  This division has been handed down from the time of Bartholine, who,
not suspecting the absorbing powers of the lymphatics, held them only as
organs of circulation for restoring to the heart die serum of the blood. The
sagacious mind of the late Dr. W. Hunter first imagined their absorbing
powers, and established the theory of their identity of function, in this re-
spect, with the lacteals.  The priority of the theory was warmly contested
for Dr. Monroe, of Edinburgh. 
286
CIRCULATORY SYSTEM.
               Of the Lymphatic Glands.

   The Lymphatic or Absorbent Glands or Ganglions, some-
times called waxen kernels in common language, are an ap^
pendage of a very important  description to  the absorbent
system.  They are flattened ovoidal bodies, of a reddish ash
colour,  indurated so as to afford a strong resistance to pres-
sure, and of a  variable volume  from  a line to twelve lines
in their long diameter.  They are found principally in clus-
ters or chains,  and more abundant in the neck, in the groin,
in the arm-pit, in the mesentery, and about the  bifurcation
of the trachea.
   The lymphatic vessels, in  their course towards the tho-
racic duct have to pass through one or more of these glands.
This rule is almost universal; some  exceptions, however,
to it in the case of  the lower  extremity, have been  stated
by Mr.  Hewson,  and in the case of the back by Mr. Cruik-
shank;* the latter believes Mr. H. to have been under some
misapprehension in this statement concerning the extremi-
ties, as it had not been verified by the result of his own in-
vestigations.   The vessels that enter into  the  glands are
called vasa inferentia, while  those that depart  from them
are the vasa efferentia.  As, owing to the juxtaposition of
many of these  glands, the vessels between  them are very
short, this distinction would  likewise seem  almost  super-
fluous, because one has scarcely space to apply the term ef-
ferentia, before the same vessels enter into the consecutive
gland, thereby  becoming  inferentia.   For the most part,
the vasa inferentia are less numerous  and somewhat  larger
than the  efferentia.  The former, as they leave  the gland,
radiate into smaller branches, while  the  latter are formed
from the convergence of smaller branches.
  Each  lymphatic  gland  is surrounded  by  a capsule, re-
sembling condensed cellular substance, which adheres very
closely to the gland, and from which cause many anatomists
are disposed to deny its  existence, at least  as  a  distinct

    * Anat. of Absorb. Vessels, second Edit p. 79. London, 1790. 
          ANATOMY OF THE ABSORBENT SYSTEM.       287

membrane.  They  are also abundantly furnished with  ar-
teries and with veins destitute of valves; but though they
are penetrated  by nervous filaments,  it is not yet satisfac-
torily ascertained that any remain  with  them; it is, how-
ever, more probable than otherwise. Their connexion with
the surrounding  cellular substance is sufficiently loose to
permit them, in  certain  parts, to  be  slid moderately back-
wards  and forwards.  When this motion is arrested, it is
from inflammation  about them.
  The capsule of the lymphatic gland,  like that of other
glands, sends  processes  within to keep  its  parts together,
and to conduct the blood vessels.   It  also contains a pecu-
liar fluid called, by Haller, succus  proprius, which is prin-
cipally found in young animals, diminishes  as they advance
in age, and finally  disappears  It is of various colours, but
more frequently white; it appears to have globular particles
in  it,  which the  late Mr.  Hewson, for  divers reasons,
thought to become afterwards the red globules of blood.
   When a lymphatic gland is injected with quicksilver, it
appears to be made up by  the minute  branching of the vasa
inferentia, and  the roots of the vasa  efferentia, the former
being continued into the latter. There is also some appear-
ance of small cells  intermediate to  these two orders of ves-
sels.   All anatomists admit the  former opinion, but many
reject the latter,  under a presumption that the appearance is
delusive.  The  arguments,  however, seem to be in favour of
their existence.  Mr. Cruikshank,* whose address in these
matters was certainly of the first order, declares that he
never failed to perceive them, and  particularly well, just
as the mercury was entering the gland.  This arrangement
is still more readily made  out in  animals, as the horse,  ass,
mule.  It also seems, from  his observations, that when there
are more than one  vas inferens and effereos, tiere are cells
for each set, which are  kept distinct from  the cells of the
others, though they communicate freely with their cognates.
Mr. Abernethy's investigations 01  the mesenteric glands of
whales, coincide with the views of  Mr.  Cruikshank: he
* Loc. cit. p. 85. PI. in, 
288
CIRCULATORY SYSTEM.
states, indeed, the cells  as being large spherical bags, into
which the lacteals plainly open.  The celebrated Mascagni
also acknowledges, and, indeed, describes the cellular struc-
ture of these glands,* which he  had ascertained both by
quicksilver  and by wax  injections.  The improved notions
of modern anatomy upon what is  called the erectile tissue,
that is, the cells intermediate to arteries and veins, as in the
penis and other places, now considered rather as the dilated
extremities of vessels, would  also assist in warranting the
opinion advocated.  The  celebrated Ruysch thought that he
had discovered acini in the lymphatic glands, and sent his
injected  preparation  illustrative of  them  to  Boerhaave.
Some idea of the enthusiasm of the old anatomists  may be
conceived by his saying,  " quando jam clarius et perfectius
videbam haec omnia, prae gaudio exsiliebam."
  When the absorbing powers of the lymphatics had been
established by Dr. W. Hunter, they were for a long time
considered as the exclusive functionaries in this operation;
and the opinions previously entertained had sunk into such
disrepute from some experiments of Mr. John Hunter,t that
they were considered rather as food for literary research and
curiosity, than for deliberate adoption.   In the year 1809,
M Magendie reported his experiments on absorption, which
seemed to favour the notion that the veins also assisted  in
this office,  a theory as ancient as Galen.   The more recent
observations of Fohman, in 1821,  and Lauth, in 1824, on
the communications of the lymphatics with the veins, in the
midst of the tissues of organs, and in the lymphatic glands,
seem now to explain away again the theories of the absorbing
powers of the veins, and to reinstate the lymphatics in their
reputed exclusive functions.  It is also stated that an ana-
tomist of Florence, M. Lippi, has still more  lately found
several large lymphatic  trunks entering into the ascending
cava.   The connexion of the lymphatic  system with the

       * Vasor. Lymph. Hist.       f Med. Commentaries. 
          ANATOMY OP THE ABSORBENT SYSTEM.       289

vena cava ascendens, and also with the external iliac veins
has been further demonstrated by certain preparations, ex-
hibited by M.  Amussat to the Academie Royale.* M. Fo-
dera has,  however, again brought the subject under discus-
sion, by  multiplying the active agents of this function, and
says, that his  experiments  prove that all organized tissues
enjoy it, and not certain parts only, as has been heretofore
supposed;! from which  it results that most of the rules in
regard to the application of local remedies are inexact, and
that we should have  more regard to the thickness and den
sity of tissues,  to the quantity and rapidity of their circula-
tion, than to simple locality.}
                     CHAPTER VI.

OF THE SPECIAL ANATOMY OF  THE ABSORBENT SYSTEM.

  SECT. I.--OF THE ABSORBENTS OF THE HEAD AND NECK.

   The Superficial Absorbents of the head are found in com-
pany with the several branches of the temporal, the occipi-
tal, the frontal, and the facial arteries,  and, in order to get
into the lymphatic trunks  leading to the thoracic duct, fol-
low or rather reverse the course of their respective arteries.
There are at least two absorbent trunks for  one arterial, and
frequently more: those on  the fa'ce are  more abundant than
such as are on the side of the cranium,  owing to the excess
of cellular substance on the former.  The absorbents of these

  * Am. Med. Jour. vol. i. p. 422.
  f Recherches Experimentales sur PAbsorption et 1'Exhalation.  Paris,
1824.
  * For a most interesting and instructive series of experiments on the laws
and phenomena of absorption, see Philadelphia Journal of the Medical and
Physical Sciences.  Nos. 6 and 10.  The experiments were executed by
Messrs. Lawrence, Coates, and Harlan, of this city.
   Vol. II.—37 
290
CIRCULATORY SYSTEM.
two regions anastomose freely beneath the external ear, be-
tween the skin and the parotid gland.
  The Deep-Seated Absorbents of the head have been fol-
lowed  to the membranes of the brain,  but  not further.
Ruysch observed them between the tunica arachnoidea and
pia mater, inflated with ;-ir, and called them vasa pseudo-
lymphatica.  Lancisius, Pacchioni, and others, assert their
having found them in the pia mater.  Doubts, however, are
cast upon these several  observations, owing to such vessels
not having  been injected with quicksilver, and  from the
want of a valvular appearance in them:  also from the want
of lymphatic glands in the brain.  Their existence,  however,
would  seem to  be  sufficiently  proved, both  from general
analogy, and from affections of the brain producing swellings
in the glands of the neck.   On the  dura mater they have
been traced along the course of its arteries.  They descend
from the interior of the cranium  into  the neck,  along the
carotid  and vertebral arteries.  The absence of lymphatic
glands in the cranium may be accounted for from the fact,
that the ready tendency of these organs to swell upon slight
causes of irritation, would have  rendered the individual
liable to death from compression of the brain, by their tu-
mefaction.   Mr. Cruikshank  has found lymphatic glands in
the carotid canal.
  The Deep Lymphatics of the face, as those from the in-
terior of the nose, of the orbit, of the  tongue and mouth,
attend the arteries which respectively supply those parts.
  These several absorbents, from the surface and from the
interior of the head, descend to the base of the cranium, and
then begin to pass through the chain of lymphatic glands
situated along the course of the great blood vessels  of the
neck.   They lie, for the most part,  under the sterno-mas-
toid muscle, and, when successfully injected, are thought to
form the most brilliant plexus of absorbents in the whole
frame.    On each side of the  neck, one or more common
trunks are at length formed;  that on the left side joins the
Left Thoracic Duct near its termination,  while the one on
the right assists  in forming the duct, peculiar to  that side, 
         ANATOMY OF THE ABSORBENT SYSTEM.      291

the right Thoracic Duct, or more properly called, Brachio
Cephalic.
  The lymphatic vessels of the muscles of the  neck,  and
those of the thyroid gland,  enter  into  the trunks of the
neck.  According to Mr. Cruikshank, those of the thyroid
gland may be readily injected  by plunging a lancet at ran-
dom into its substance,  and then introducing  air or quick-
silver.


    Of the Absorbent Glands of the  Head and Neck.

   The  only claim of lymphatic glands to an existence in
the cavity of  the cranium, is founded  upon a supposition
that the Pineal, the Pituitary,  and  Pacchioni's  Glands are
of  this character; but it is far from being established, and
there seems indeed to  be some doubt whether the glands
found in the carotid canal, by Mr.  Cruikshank, are not the
carotid ganglion of the  Sympathetic, lately noticed by Lau-
monier.
   On the external surface of the cranium, over the inser-
tion of the sterno-mastoid muscle,  there  are from four to
six of a small volume;  on the  face there are one or more
small ones, below the zygoma,  and from two  to four on the
external surface of the parotid; there are one or more small
ones situated  in the substance of the parotid gland, which,
according to Burns, are generally the seat of tumours falsely
attributed to the parotid itself.   There are also some small
glands along the facial artery as it ascends from the base of
the jaw to the corner of the mouth.
   On the neck there are two or more small glands, immedi-
ately under the skin of the symphisis of the jaw, and eight
or  nine around  the submaxillary gland.   The most nume-
rous congeries of glands on the neck is, however, along its
great blood vessels, and covered more or less by the sterno-
mastoid muscle,  being principally between  its posterior
margin and the anterior of the trapezius.   Along the latter
line there are about twenty, in addition to six just above
the superior margin of  the clavicle.   On the  trachea, just 
292              CIRCULATORY SYSTEM.

above the sternum, there are four,  forming the upper end
of a series which descends along the oesophagus and trachea
to the root of the lungs.


SECT. II.--OF  THE  ABSORBENTS OF THE UPPER EXTREMI-
  TIES, AND OF THE CONTIGUOUS PARTS OP THE TRUNK OF
  THE BODY.

  The  superficial absorbents of the  upper extremity are
very numerous, and lie  between its skin  and aponeurosis.
They begin at the ends of the fingers and thumb; there be-
ing two or more branches for each, both before and behind.
The posterior branches pass to the back of the hand and of
the fore-arm;  some  of them,  more especially those from
about the thumb,  run  up along the radial side of the fore-
arm to the bend of the arm;  but by far the greater part of
them  incline very  gradually in a semi-spiral manner to-
wards  the ulna, and then to the front of  the  fore-arm.
  Such of the superficial vessels as come from the front of
the fingers and hand, continue to ascend straight up the fore-
arm to its bend.  These vessels of the fore-arm  are so nu-
merous that for every few lines there is an ascending trunk
on its circumference:  some of them coalesce, others form
plexuses,  and their number is  much reduced at the elbow.
  From the elbow the superficial lymphatics ascend to the
axilla in fifteen or twenty parallel  trunks,  along the inter-
nal margin and the front  surface of the biceps flexor cubiti.
The  outer side of the  arm has comparatively but few ab-
sorbent trunks upon it,  but some few trunks follow the
course of  the cephalic vein, penetrate  with it into the axil-
la, and then join the inferior lymphatics of the neck.

  The Deep Absorbents of the upper extremity  attend the
arteries,  and are at least two for each principal artery.
They anastomose with the superficial ones from  time to
time,  and at last terminate in the axillary glands.  As they
follow strictly the course of the arteries, a further specifi-
cation is needless. 
        ABSORBENTS OF THE UPPER EXTREMITIES.     293

  The Superficial Absorbents of the contiguous portions of
the trunk of the body are not by any means so numerous as
those of  the upper extremity; they consequently are more
distant from one another, and they also go along in a more
serpentine manner.  From the nape of the neck to the low-
er part of the loins they all converge  to the arm-pit.   The
absorbents which are situated on the front of the  pectoralis
major muscle, and those on the side  of the body from the
arm-pit to the hip, also  converge to the axilla.   In regard
to the two latter places, however, some of their absorbents
by penetrating the parietes of the thorax or abdomen, re-
spectively join  the  internal  absorbent trunks of these ca-
vities.
   These several lymphatics  from the upper extremity and
from the trunk, traverse the  axillary glands, and are suc-
cessively reduced  in number  to four  or five voluminous
trunks, which surround the subclavian artery.  While in
the axilla fhey are re-enforced  by the deep lymphatics from
beneath the pectoralis major,  the latissimus dorsi, and the
shoulder.   Their number  being again  reduced, they go
along the subclavian vein over the first  rib; those of the
left side open either  into the  thoracic duct at its termina-
tion, or into the subclavian vei'»  near it; but those on the
right are finally assembled into the single large trunk, bra-
chio cephalic, which discharges into  the angle of junction
of the right internal jugular and subclavian vein.


      Absorbent Glands of the Upper  Extremity.

   These glands are rarely found on the fore-arm, but when
they do  exist, it is in the course of the deep absorbents, and
they  are very small, and but  few.   From one to four are
found scattered on the front of the elbow and internal  con-
dyle.  From four to seven exist along the sheath  of the hu-
meral vessels and  nerves.
   The axillary glands are very numerous, and of different
sizes; they are dispersed throughout  the  cellular  substance
of the axilla,  reposing on the serratus major anticus, be- 
294
CIRCULATORY SYSTEM.
tween the pectoral muscles and  those of the shoulder, and
being for the  most part below the  axillary  vessels  and
nerves,  but some reposing immediately upon them,  and
forming  a chain from  the lower part of the axilla to the
clavicle.   Their number is from  fifteen to thirty-five or
forty.   All  the absorbents which  observe the rout of the
axilla to  reach the thoracic duct have to pass through these
glands.


SECT. III.—ABSORBENTS OP THE INFERIOR  EXTREMITIES,
  AND OP THE CONTIGUOUS PARTS OF THE TRUNK OF THE
  BODY.

  The superficial absorbents, like those of the upper extre-
mity, are placed between the  skin and the aponeurosis, in
the cellular tissue that  contains the subcutaneous veins.
They are also very abundant, and are found every few lines
on the circumference of the limb; they are, however, more
numerous internally, than externally, and for the most part
run upwards.
  Those on the inner or anterior side of  the limb, are first
perceived on the back of the toes  and foot.   They incline
over the front of the ankle, and its internal face to the in-
ner side of the leg; they then ascend over the  inner side of
the knee, and along  the same side of the thigh to the groin.
The superficial absorbents of the back of the lower extremity
are first perceived on the sole of  the foot.   They ascend
along the back of the outer ankle and of the leg above the
knee; they  then  incline semispirally  inwards,  so as to
bring themselves to the front of the thigh.  These several
absorbents, though there are but few on the foot, augment
continually  in  number  by new accessions in  their ascent.
All those on the posterior internal  face of the thigh wind
over its  internal  side,   while such  as are on  its posterior
external face wind over the outer side, to reach the ingui-
nal glands.

   The Deep Absorbents adhere to the arteries, being at least 
       ABSORBENTS OF THE INFERIOR EXTREMITIES.    295

two to each, and adopting the same distribution and nomen-
clature.  The anterior tibial begins in the sole of the foot,
and arises to its back between the two first metatarsal bones;
another branch begins on the dorsum  of the foot.  The  first
pursues the course of the anterior tibial artery through the
interosseal ligament to the ham; the second  frequently joins
the peroneal absorbents about half way up the leg.  The pos-
terior til.i .1 and the peroneal absorbents, as they cruise along
their respective arteries, do not require any further com-
ment.  There is a fourth set of these deep absorbents, amount-
ing to two or  three in number, which attend the external
saphena vein, and come  from the external side of the foot.
Getting between the heads of  the gastrocnemii  muscles,
they are  re-enforced  by other trunks from this muscle;
some of the branches then associate themselves with the su-
perficial lymphatics, and others penetrate  the ham so as to
join the deep trunks there.
   The deep  absorbents of the leg  coalesce partially in the
ham and ascend along the popliteal artery.  On the thigh,
there are from four to eight of these trunks attending the
femoral artery, and receiving additions as the latter detaches
branches.

   There are two or three lymphatic vessels on each side of
the penis, which begin  at its glans  and prepuce, and tra-
versing the length  of this organ, wind above the external
abdominal ring to join the nearest inguinal gland.  There are
several from the side of  the scrotum  and perineum, which
ascend along  the chord  and thigh to join also the nearest
inguinal gland.  In the female, those of the labia externa and
clitoris correspond  with  those of the scrotum and penis.
   The superficial absorbent trunks, from the lower front of
the abdomen, are not numerous; they descend and converge
also  to the inguinal glands.  Some of those from  the loins,
such as do not ascend to the axilla, advance to the inguinal
glands. Those of the buttocks do the same. 
 396              CIRCULATORY SYSTEM.

       Absorbent Glands of the Lower Extremity.

   Absorbent Glands, below the knee, are not abundant, or
 indeed very common; yet one or two exist sometimes in the
 course of the anterior tibial artery in the upper part of the
 leg.  The popliteal glands are three or four;  they are small
 and scattered  at wide intervals  in the fat of the ham around
 its vessels.   From the  latter  to the groin, they are not
 usually found at all.
   The Inguinal Glands are amongst the largest in the sys-
 tem; they repose along  the  anterior margin  of Poupart's
 ligament and a little below, and are readily felt beneath the
 skin.  The  superficial vary in  number, in different indivi-
 duals, from seven to twenty, being more numerous as they
 are smaller, and are placed between the laminae of the fascia
 superficialis.  They  receive, first of all, the superficial lym-
 phatics of all the parts  mentioned.   The  deep-seated are
 smaller, are a little lower down on the thigh, and lay along
 the course of the femoral artery, beneath the aponeurosis of
 the thigh; they are  from three to seven in number, but are
 much less constant than the superficial.


      SECT. IV.--DEEP ABSORBENTS OF THE PELVIS.

   The Deep Absorbents of the parietes of the pelvis, as in
 other cases, attend the arteries of the part and have the same
 names.  The obturators come from the heads of the adductor
 muscles, and, passing through the obturator foramen, end in
 the hypogastric glands.  The ischiatics come from the small
muscles on the back of  the hip joint, and getting  into the
pelvis along with the sciatic artery, they also terminate in
the hypogastric glands.   The gluteals come from the three
gluteal muscles, and  entering the pelvis along with the ar-
tery at the superior  margin of the sciatic notch, they like-
wise terminate in the hypogastric glands along with some
vessels from the anus and the perineum.  The ilio-lumbar,
 the sacral, and the  circumflex iliac absorbents, also follow
 their respective arteries and terminate in the nearest glands. 
            DEEP ABSORBENTS OF THE PELVIS.        297

   The absorbents of the Testicle are  numerous and large;
according to Dr. W. Hunter,* they can sometimes be very
completely  injected by a pipe thrust into the substance of
the testicle, and  according to Cruikshank, very advantage-
ously from  the vas deferens, t They form two layers, one
superficial coming from  the  tunica vaginalis testis, and the
other from the substance of the gland.  They finally unite
into some six or eight trunks, X which ascend with the chord
through  the abdominal canal. Occasionally one or more of
them is as large as a crow-quill.  By following the  course
of the spermatic artery, they at last  terminate in the lumbar
glands.
   The deep absorbents of the Penis accompany the arteries,
and therefore either get into the  pelvis  beneath the sym-
phisis of the pubes, or  along the crura and  the tuberosities
of the ischia; hence a chancre on the prepuce causes bubo,
while one  on the glans very rarely does, and yet the con-
stitution will be equally affected. §  These  absorbents ter-
minate in the hypogastric glands.
   The deep absorbents of the Clitoris follow, in the same
way, the internal pudic  artery.
   The absorbents of the Urinary Bladder are also numerous,
and pass in several trunks from its sides to  the hypogastric
glands. Those of the prostate gland and vesiculae seminales
are associated with them.
   The absorbents of the lower part of the vagina accompany
the round ligament of the uterus through the abdominal ca-
nal, and finally anastomose with those of the uterus.  Those
of the upper portion of  the vagina  are immediately associ-
ated with such as belong to the  uterus.
   The absorbents of the uterus  are not so well seen  in the
unimpregnated state, but in impregnation they are so pro-
digiously numerous, that when  injected  with quicksilver,
one is almost tempted to suppose that the  uterus consists
entirely in them.  Mascagni's plate on this subject is an ex-

     * Loc. cit.                    f Loc. cit. p. 155.
     t Mascagni, loc. cit.             § Cruikshank, Joe. cit.
   Vol. II.—38 
298              CIRCULATORY SYSTEM.
quisite specimen.* As they all terminate in the hypogastric
trucks, the latter are in such case as large as goose quills.t
  The hypogastric plexus,  from these several  accessions
from the parietes  and viscera of the pelvis,  becomes very
numerous, and follows the course of the hypogastric artery
in ascending into the loins.
  There are likewise some  spermatic  absorbents in the fe-
male, called so from attending the vessels of the same name.
They come from the ovarium, the  Fallopian tube, and the
round  ligament, to terminate in the  lumbar  glands; they
anastomose below with those of the uterus.

              Of the Glands of the Pelvis.
  Some few glands lie beneath the gluteus maximus muscle,
but the  majority are within the pelvis.   Those which are
called  the External Iliac  are at least six, frequently more,
and extend from  Poupart's Ligament to the  lower part of
the loins,  being  planted  along the external  iliac artery,
both above and below.  The Hypogastric or Internal Iliac
Glands are rather more numerous than  the others, and form
a chain along the hypogastric artery.   The latter are much
disposed to form large indurated masses from diseases of the
rectum, uterus, and  bladder. %


  SECT. V.—ABSORBENTS OP THE ORGANS OP DIGESTION.

   The Absorbents of the Stomach are very numerous, and
lie in  two planes; one is superficial, being immediately be-
 neath  the peritoneal coat, and the other  is profound,  being
placed between the  muscular and the  mucous coat.   They
 are finally assembled into three divisions, which follow the
 course of the principal blood vessels of this organ.
   One division, coming from the anterior and the posterior
 faces of the stomach, converges to  its  lesser curvature,  and
 passes through some six or eight small glands in  the adja-
 cent portion of the lesser omentum.   Inclining to the right
 of the cardiac orifice, they then pass  through some glands

    * Loc. cit.    f Cruikshank, loc. cit.    % Cruikshank, loc. cit. 
       ABSORBENTS OP THE ORGANS OP DIGESTION.    299

common to them and to th*e deep lymphatics of the liver.
Their numbers being reduced, they then descend  behind
the pancreas, and terminate in the thoracic duct near the
coeliac artery.
   The second division comes from the left inferior  portion
of the stomach and from its greater extremity, and blending
with the absorbents of the spleen and pancreas, goes  with
them into the thoracic duct.
   The third division comes from the right inferior  portion
of the stomach, and assembling towards the pylorus, are sub-
sequently mixed with some of the absorbents of the liver and
of the small intestines, and go along with them into the tho-
racic duct.

   The  absorbents of the Great Omentum join those of the
 stomach and of the  colon at the points most convenient to
 them.

   The  absorbents of the Small Intestines,  like those of the
 stomach, are both superficial and deep, and from the  func-
 tion of conveying chyle, have been called  lacteals or chyli-
 ferous vessels. As the chyle, however, can only be absorbed
 by the deep ones; and as they and  the superficial have com-
 mon trunks; as they also absorb, from the  intestines,  fluids
 not converted into chyle, there seems to be no necessity for
 distinguishing them by a particular epithet.  The deep are
 in the cellular coat of the intestine, and follow the ramifica-
 tions of the arteries, being double their number.  The super-
 ficial being immediately beneath the peritoneal coat, run for
 some distance longitudinally on the  gut, and then turn off
 to the mesentery at right angles.
   On the mesentery these absorbents are not rigidly bound
 to the course of the blood vessels; they converge in a slightly
 tortuous manner from its circumference to its root.   They
 anastomose with one another, by which their number is re-
 duced; and they also have to pass through the series of me-
 senteric glands. The lacteals of the duodenum, and jejunum
 are larger -Mid more  numerous than those of the ilium,  in the
 proportion of the greater extent of the internal surface of the 
300
CIRCULATORY SYSTEM.
former intestines, from the number of their valvulae conni-
ventes.   The vessels of the mesentery, after having cleared
the series of glands,  and held some intercourse  with the
lymphatics of  the spleen, liver, stomach, and pancreas, are
reduced at last into one or more large trunks, which, observ-
ing the course of the superior  mesenteric artery, empty
near the root of the latter, but sometimes lower down, into
the thoracic duct.

  The Absorbents of the Large Intestines are much less nu-
merous than those of  the small.   They are also superficial
and deep, and observe the course of the blood vessels. Those
from the right portion and middle of the colon join the lacteals
of the mesentery, while such as belong to the sigmoid flex-
ure follow the inferior mesenteric  artery up to the lumbar
glands.   Those of the rectum go partly into the lumbar
and partly into the hypogastric  glands, and  as  its  blood
vessels are more numerous  than those of other portions of
the large intestines, its absorbents are in the  same propor-
tion.*

  The Absorbents of the Liver are exceedingly numerous,
and are also injected with unusual ease from the larger into
the smaller trunks, from the imperfection of the valvular
arrangements.   They are also superficial and  deep.
  The Superficial Absorbents of the upper surface of the
liver run in  several divisions, the number of which  is un-
settled.   Those near the middle front of the liver assemble
into six or more trunks, which ascend the suspensory liga-
ment, and enter the thorax  between the diaphragm and the
sternum.   They are joined  by several trunks  from the dia-
phragm, and continuing to ascend up the anterior  mediasti-
num between its laminae behind  the sternum, they are re-
enforced  by contributions from the pericardium,  from the
thymus gland, and from the anterior parietes of the thorax.
The division then crosses the upper end of  the descending
cava, and  those from the two sides assembling, they go in
one or more large trunks along the vena  innominata, and
finally empty into the left thoracic duct near its termination.
                   * Cruikshank, loc. cit. 
       ABSORBENTS OP THE ORGANS OF DIGESTION.    301

Sometimes they enter into the  right thoracic duct.   It oc-
casionally happens that a detachment of this division instead
of ascending through the mediastinum is directed towards
the coronary ligament of the liver, and being there joined
by other vessels, it enters immediately into the thoracic duct
at the upper part of the abdominal cavity, or at the lower
of the thorax.
   Another division comes from the upper surface of the right
lobe, and gaining the right lateral ligament, penetrates into
the thorax through the  diaphragm, and advancing along the
costal margin of this muscle, terminates in the first division
under the sternum. Sometimes one of its branches, thrice as
large as a crow quill, runs backward to the spine, and is in-
serted into  the thoracic duct behind the oesophagus, without
passing through any gland; there are also, occasionally, se-
veral other arrangements, of the trunks of this division.*
   Another division comes from the upper surface of the left
lobe of the liver, and its trunks advancing to the left lateral
ligament, get into the thorax through the diaphragm.  Some
of the trunks then run forward on the convexity of this mus-
cle, to  terminate in  the trunks under the sternum, while
others retire backward to end in the glands around the oeso-
phagus immediately above the diaphragm.
   There are various departures from this general arrange-
 ment of the absorbents on the  upper surface of the liver; as
 their trunks invariably reach the thoracic duct ultimately,
the particular routes do not seem to be rigidly fixed.
   The superficial absorbents of the under surface of the liver
present also, diversities, but they are seldom arranged into
so many divisions as those of the upper surface.  They com-
municate freely with the latter, and also with the profound,
and finally assembling in the transverse fissure, they descend
along the capsule of Glisson to join and anastomose with the
contiguous trunks from the alimentary canal, from the pan-
creas and the spleen.
   The Deep Absorbents of the liver follow the branching of
the vena portarum, and emerging at the  transverse fissure
pass through the glands in the capsule of Glisson, associ-
                    * Cruikshank, loc. cit. 
302
CIRCULATORY SYSTEM.
ating themselves at the same time with the superficial trunks,
and having a common termination with them.   By putting
a ligature around the vena portarum of a living animal many
of them are included in it, they then become  exceedingly
turgid, and are seen to diverge through the liver  like the
pori biliarii.
  The liver is said to be more abundantly furnished with ab-
sorbents than any other viscus.

  The Absorbents of the  Spleen are  also superficial  and
deep seated.  The former are between the peritoneal and the
proper coat, and are injected  with some difficulty in the hu-
man subject,  but are very demonstrable  and numerous in
the calf.  The latter emerge at the fissure of the spleen, and
traversing the glands that lie  along the  course of the splenic
artery, receive successively the absorbents from the pancreas.
They finally end in the thoracic duct, after reciprocal junc-
tions and anastomose with the  vessels from the  stomach
and liver.

  The Absorbents of the  Pancreas are also numerous,  and
may be injected contrary to their circulation from those of
the liver.   They arise from  the  substance of the pancreas
like its vessels  by short trunks, which  join those of the
Splenic Plexus at right  angles.

  The Absorbents of the Kidneys are superficial and deep;
the former, though numerous, are too  small in  the healthy
state of these organs to be well seen, but  they become very
distinct from disease, and  converge from its periphery to
its  fissure.   The deep absorbents accompany  the vessels,
and emerging with them at the fissure  are joined with the
superficial; they all then run along  the  emulgent vessels,
and have frequent anastomoses with those of the testicles or
ovaries, and with those of the capsulae  renales.   These ab-
sorbents may be filled by putting a pipe into the excretory
duct of the kidney.

  The Absorbents of the Capsulae Renales  unite to those
from the kidneys, and,  therefore, terminate with them in
the lumbar glands. 
       ABSORBENTS OF THE ORGANS OP DIGESTION.    303

      Of the Absorbent Glands of the Abdomen.

  The cavity of the  abdomen contains many more glands
than any other region of the  body, both on account of the
very great extension  of the serous system in it, of the func-
tions exercised by its viscera, and of its being traversed by
the absorbents  of the lower  extremities.  Many of  these
bodies have already been described under the denomination
of hypogastric,  and   external iliac; in addition  to which
there are a few between  the  laminae of the mesorectum in
front of the sacrum.

   The Mesenteric Glands are  exceedingly numerous, and
amount to between* one  and two hundred: they begin at an
inch or two from the small intestines, and may be traced to
the root of the mesentery, being placed between its layers
on the convex side of the upper mesenteric artery.  As the
intestinal canal is longer in some individuals than in others,
they are  proportionately more numerous.  Their largest
size seldom exceeds  that of an  almond; those belonging to
the jejunum are rather more  developed than such as belong
to the ileum, and they all augment in size as they approach
the  root of the mesentery.

   The Glands of the Mesocolon are placed between the la-
minae of this membrane, near the intestine;  they receive
the absorbents from  the  large intestines,  are much smaller
than those of the mesentery, and their number seldom ex-
ceeds fifty.   Some few of them are situated near the root
of the mesocolon.   They are by no means  so disposed to
tumefaction from scrofulus  affections as  those of the Me-
sentery.   It is stated by Winslow that he demonstrated to
the Academy  of Sciences at  Paris,  chyle in the absorbents
of the Mesocolon; this  fact  will assist us in accounting for
the effects of nutritive glysters.

   The Gastro-Epiploic  Glands, are situated between the la-
minae of the omenta, where they join the  curvatures of the 
304
CIRCULATORY SYSTEM.
 stomach.   Their number seldom exceeds four or five for
 each curvature, and they receive the lymphatics of the sto-
 mach and omenta.

   The Caeliac Glands are those which belong to the liver,
 the spleen, and the pancreas: they follow the course of the
 blood vessels of these organs,  and are traversed by their
 absorbents.  The trunk of the vena portarum is surrounded
 by them,  and Mr. Cruikshank  says, that  he has  seen  the
 biliary and pancreatic ducts in a state of compression from
 their tumefaction.

   The Lumbar Glands are very numerous and large; they
 are scattered over the whole region from the base of the
 sacrum to the pillars of  the diaphragm, lying on each side
 of the bodies of the  lumbar vertebrae, and  in front of the
 abdominal aorta and vena cava,  being concealed by the root
 of the mesentery and of the mesocolon.    They may be
considered as continuations of all  the preceding congeries
of glands in the abdomen, and, therefore, when they, along
 with the vessels  leading to them,  are successfully  injected,
 they form so thick a  plexus of absorbents,  reaching from
the pelvis to the concavity  of the diaphragm, that the great
 blood vessels can scarcely be seen for them.   Many of the
vessels reaching from one to another, are as  large as a crow
 quill.

 SECT. VI.--ABSORBENTS OP THE VISCERA OF THE THORAX.

  The Absorbents of the Lungs are  thought to be next in
abundance after those of the liver,  and are likewise divided
into two sets, the superficial and the deep seated.   The
former are  beneath the  pleura pulmonalis.    Mr.  Cruik-
shank* says, that they are not always to be  found, though
commonly he has readily shown them  covering with their
meshes the whole external surface of the lung.  The larger
 meshes follow the interstices of  the lobules, and within
* Loc. cit. p. 194. 
      ABSORBENTS OF THE VISCERA OF THE THORAX.   305

them are others  of extreme delicacy.   The  same author
states that one of the easiest methods of finding them, is to
inflate the lungs of a still-born child,  from the trachea, and
the air passing from its  proper cells, will  get into the ab-
sorbents; a puncture being then made into one of the latter,
quicksilver may be very readily introduced. Some of their
trunks penetrate to the bottom of the fissures of  the lungs,
and pass  through the glands there, while  others continue
more superficial along the internal face of the lung, and so
reach the bronchial glands.
   The deep absorbents of the  lungs observe the course of
the  pulmonary vessels and of the bronchise.  They arise
from the substance of  the  lung, anastomose very freely
with the superficial vessels, and,  in parting from the lung,
pass through the  bronchial glands, where they  are joined
by the superficial.
   By the junction of the branches from the left lung, three
considerable trunks are formed;  one, which is  sometimes
the  size  of a goose quill, is inserted  into the thoracic duct,
immediately behind the bifurcation of the trachea; another
ascends between the trachea and the oesophagus,  to join -the
thoracic duct near its termination; and the third joins the
glands belonging to the absorbents of the heart*
   The absorbents of the right lung also coalesce into three
principal trunks  at the root  of the  lung, one of them as-
cends across the front of  the superior cava, making in its
course, many elegant convolutions, and at length terminates
in the second trunk on  the left side.t   The other trunks,
ascending on the side of the trachea and having traversed
their glands, discharge into the right  thoracic or brachio-
cephalic trunk, or else near it into the right internal jugu-
lar,  or into the right subclavian vein.  There are, in these
respects, diversities in different subjects.

   The trunks of the  Absorbents of the Heart follow the
course of the coronary vessels, and distribute themselves by
branches over its whole surface.   They are, without pre-

     * Cruikshank, loc. eit.             f Cruikshank, loc, cit,
   Vol. II.—39 
306
CIRCULATORY SYSTEM.
vious management, easily discovered; but if the  heart be
macerated in water for several days, so as to become some-
what putrid, the absorbents are filled and distended by the
gazeous exhalation: on the puncture of one of these vessels
and  the introduction of a  pipe, they may all be readily
filled.
   There are three principal trunks of these absorbents; one
follows the  right coronary artery to the root of the aorta,
and  then ascends over the front surface of the latter to the
top of its arch, where  it enters a gland.  The other two
trunks follow the two principal branches of the left coronary
artery, and, coalescing  near its  origin, they ascend to the
bifurcation of the pulmonary artery, and from that along the
posterior face of the arch of the aorta, to enter a  gland be-
tween it and the trachea. These several vessels subsequently
traverse the lymphatic glands about the trachea, common to
the  heart and to the lungs;  and ultimately terminate under
varied  circumstances, either directly  or indirectly, in the
left thoracic duct, the left internal jugular, or the subclavian
vein.   Mr. Cruikshank says that the  right coronary trunk
empties into the lymphatic  trunks of  the right side of the
neck, which shows that there is no fixed arrangement.

   The Absorbents of the Pericardium may also  be found;
 they terminate, like the others of the heart, in the bronchial
 glands, and are particularly associated with  those of the
 thymus gland.

   The Absorbents of the Oesophagus are so numerous as to
 form a plexus  from one  end to the other of it.  They run
 into the bronchial glands, and therefore have a common ter-
 mination with the absorbents of the heart and lungs.   Mr.
 Cruikshank says, that  he has  reason  to believe that he has
 seen life sustained through them alone and the absorbents of
 the mouth,  in a  case where stricture prevailed for  some
 months just above the cardia, and where the food, after re-
 maining for three  or five minutes in the oesophagus, was
 vomited up.*

   * A case somewhat similar has occurred in the practice  of Dr. Physick. 
      ABSORBENTS OF THE PARIETES OF THE TRUNK.   307

  The Absorbents of the Thymus Gland are very abundant
in the infant, but diminish with the rest of the structure in
the adult: they terminate in the bronchial glands also.


  SECT. VII.--THE ABSORBENTS OF THE PARIETES OF  THE
                        TRUNK.

  In addition to the absorbents mentioned as belonging to
the internal and external parietes of the pelvis, there are
some others belonging to this cavity, as the ilio lumbar, the
sacral, and the circumflex.
  The Ilio Lumbar Lymphatics come from the parts  to
which the artery of the  same name is distributed,  and, as-
sembling into two or more large trunks which pass beneath
the psoas  magnus  muscle, one of them joins the lumbar
glands, and another the hypogastric.
  The Sacral Lymphatics  arise from the cellular tissue in
front of  the sacrum and from the spinal canal in the latter.
Emerging through its foramina in front, they terminate in
the lower part of the lumbar and in the hypogastric plexus.
  The Circumflex Iliac Lymphatics attending the artery of
the same name, arise  from the  lateral inferior parietes of
the abdomen, in the thickness of  its broad muscles, the se-
veral branches  assemble  into  a few trunks which  descend
along the posterior margin of Poupart's Ligament to termi-
nate in the external iliac plexus.

  The Epigastric Absorbents are derived from the inferior
anterior parietes of the abdomen, along the region of distri-
bution of the epigastric artery.  Their trunks coalesce into
larger ones, and descend along this artery to end in the ex-
ternal iliac plexus, near the crural arch.

  The Lumbar Absorbents arise  from the muscles of the
loins, from the posterior part of those of  the abdomen, and
from the  spinal cavity.  Their trunks correspond with the
lumbar arteries,  and passing  beneath the psoas magnus
muscle towards  the spine, they  terminate in the lumbar
giands. 
308
CIRCULATORY SYSTEM.
   The Intercostal Absorbents take their origin from the pa-
 rietes of the thorax, and following the course of their respec-
 tive intercostal arteries, pass through some small glands oc-
 casionally found  between the external intercostal muscles
 near the heads of the ribs. They are there joined by trunks
 from the spinal cavity and from the muscles of the back, and
 afterwards passing through  some small glands on the front
 of the vertebral column, they anastomose more or less with
 one another, and  finally terminate in the left thoracic  duct.
 The absorbents of the pleura costalis and of the posterior
 part of the pericardium terminate in the intercostals.

   The Internal Mammary Absorbents have their  roots in
 the anterior  region of the parietes of the abdomen, above
 the umbilicus, where they anastomose with  the  epigastric.
 They ascend, along with the internal  mammary  arteries,
 behind  the  sternal cartilages,  pass through some   small
 glands and  receive contributions  from the anterior extre-
 mities of the intercostal spaces.  Those of the left  side, as-
 sembling into one or  two trunks,  cross in front of the left
 subclavian  vein, traverse  the inferior  cervical  glands, de-
 scend afterwards from  this point, and terminate in the left
 thoracic duct, or  in one  of  the contiguous  trunks of the
venous system. Those on  the right execute the same move-
ments, but terminate in the right thoracic duct, or in one
of the contiguous venous trunks of that side.

  The Absorbents of the Diaphragm are exceedingly nume-
rous, and very much connected with those of the liver. The
anterior ones join the internal mammary absorbents, while
the posterior follow the phrenic arteries, or go to contiguous
trunks belonging to the intercostals.  The front ones on the
right side of course then terminate in the right  thoracic
duct, while  the remainder go in the various routes of the
absorbents, with which they are connected, into  the left
thoracic duct. They are principally seen on its  upper sur-
face.  Mr. Cruikshank* says, that he once saw them to the
amount of three hundred  or more, filled with chyle  from
                     * Loc.  cit. p. 90. 
      ABSORBENTS OF THE PARIETES OF THE TRUNK.   309

the mesentery, that had passed through the substance of the
liver.  Asellius was therefore probably justified by an acci-
dent of this kind, in  asserting that the lacteals went to the
liver.

  The Absorbents of the Female Mammae, like their arte-
ries and veins, are superficial and deep;  the former attend
the external thoracic blood vessels, and the latter the  inter-
nal mammary. The superficial arise from the circumference
of the  nipple, from the skin and cellular membrane, and
according to the injections of Mr. Cruikshank, communicate
freely with the vesicles of the  tubuli lactiferi. They run to-
wards the axilla, having sometimes to  pass through some
glands which  are situated halfway; they then enter the first
series of glands of the axilla in their direction, and after-
wards others successively, until they terminate in the lym-
phatic trunks  of  the upper extremity, high up in the arm-
pit.   Some few of these superficial vessels ascend over the
pectoralis major to some glands in the neck, just above the
clavicle.
  The deep absorbents of the mammae arise from their tho-
racic face, and penetrating the intercostal  spaces, join the
absorbents that attend the internal mammary artery.

        Of the Absorbent Glands in the Thorax.

  There are, as mentioned, a  few small glands in the inter-
costal spaces near the heads of the ribs, between the inter-
nal  and external intercostal muscles, intended to receive the
lymphatics of these  spaces.   There are also several small
ones, situated on  the front of the dorsal vertebrae, along the
aorta and the  oesophagus, in  the  posterior mediastinum.
There are also from six to ten along the internal mammary
artery; and some others in the anterior mediastinum,  along
the  sternal face of the pericardium.  They are said to be very
rarely affected by disease.
  The most considerable and striking glands in the tho-
rax are those  called  Bronchial or Pulmonary, which re-
ceive the absorbents of the lungs.  They cluster about the 
310
CIRCULATORY SYSTEM.
 bifurcation of the trachea, and follow the bronchia for some
 distance into the substance of the lungs.  They are from ten
 to twenty in number, and vary in  size from  an inch to a
 few lines  in diameter.  Till puberty they have a reddish
 colour, but afterwards they become  gray, and finally black,
 following, in  these  respects, the change of colour in  the
 lungs.   According  to  Mr. Pearson, their complexion de-
 pends upon the deposite of pure carbon.
   In pulmonary consumption  these glands are  always en-
 larged, and look scrofulous.


           SECT. VIII.—OF THE  THORACIC DUCTS.

   The Left Thoracic Duct (Ductus Thoracicus  Sinister) is
 the main stream of the  absorbent system, to which almost all
 the others  are but tributary, and by divers routes ultimately
 find their way into it.   It begins about the second or third
 lumbar vertebra, in front of its body.   Shortly after its com-
 mencement, while still in the abdomen, it suffers a dilatation
 more or less considerable, and varying  in its shape in differ-
 ent subjects.   This is called the Reservoir of Pecquet, or the
 Receptaculum Chyli; the dilatation,  however, is frequently
 absent and does not seem to be an essential part of the struc-
 ture; in our preparations at the University some have it,
 and others have it not.
   The thoracic duct enters the thorax  between the crura of
 the diaphragm, to the right of, and behind the aorta; it then
 ascends on the  front of the dorsal  vertebrae, between  the
 aorta and the vena azygos, in front of the right intercostal
arteries,  and behind  the oesophagus.   At the fourth dorsal
vertebra it  begins to incline in its ascent to  the left side, and
then ascends into the neck near  the head of the first rib; it
rises commonly as high as the upper margin  of the seventh
 cervical vertebra; it  then turns  downwards  and forwards,
 over the left subclavian artery within  the  scaleni muscles,
 and finally discharges into the angle  of junction of the  left
 subclavian and internal jugular veins.
   The preceding is the most simple, and perhaps the most
 common form, under which the  thoracic duct is presented, 
THORACIC DUCTS.
311
but varieties are continually occurring in its place and mode
of origin,  in its trunk, and its manner and  place of termina-
tion.   It commonly begins by the union of three absorbent
trunks; one for each side of the pelvis, along with the corres-
ponding lower extremity; and a middle one for the chylife-
rous vessels, which unites with the common trunk of the
other two a few lines above its point of formation; on  other
occasions, the chyliferous trunks join it in a confused manner
by nine or ten  distinct channels.  Sometimes an intricate
plexus of several large trunks, derived from the lumbar and
mesenteric glands; by the gradual reduction  of the number
of meshes from the successive joining of trunks; begins to as-
sume, at the crura of the diaphragm, the form  of a solita-
ry trunk, which is the thoracic duct.  The  trunk of the
duct is also disposed to keep up the anastomosing plan, even
in the thorax; we hence see it sometimes dividing itself into
two or three channels of equal sizes,  which unite again after
a shorter or longer distance, and perhaps in a  little  space
repeat the same arrangement: sometimes a small arm is sent
off, which runs alone for an inch or two, and  joins into the
parent stream; sometimes spiral turns are adopted by the
thoracic  duct,  sometimes nodosities, or small pouches, are
formed on its  sides; sometimes it is dilated at intervals in its
whole circumference.  Sometimes it splits into several chan-
nels at its termination; one channel terminating in one vein
and another in a contiguous one, of the several trunks form-
ing the vena innominata; on other occasions,  instead of en-
tering into a venous trunk of the left  side,  it goes into the
corresponding one of the right.

   Commonly  it is about the size of a large crow quill, but
sometimes as large as a goose quill, or even still more  volu-
minous, seeming to be in a varicous  state, of which Mr.
Cruikshank mentions an example where it was half an inch
in  diameter,  and  took two  pounds of mercury to fill it.
There is generally a pair of valves at the termination of the
thoracic duct,  or if it  be divided into several streams there
is a pair  at the  embouchure of each, to  keep the venous
blood out of it.   There are also  valves in its length, but
they are not numerous, and vary in different subjects. 
312              CIRCULATORY SYSTEM.

  The thoracic duct is the  grand  outlet for the lymphatics
of the left side of the head and neck, of the left superior ex-
tremity, of the intercostals, of the left side of the thorax, of
the viscera of the abdomen, and of the inferior extremities.
Though those of the viscera of the abdomen and of the lower
extremities have this route,  yet from the observations of Mr.
Lippi, of Florence, as mentioned, they have also some more
direct means of getting into  the  general circulation.  For
example, he has found several large lymphatic trunks emp-
tying into the  ascending cava, one of  them opposite  the
third lumbar vertebra; another into the primitive iliac vein:
he has also found  some of  the lymphatics of the liver dis-
charging into the vena portarum.

  The Right Thoracic Duct, (Ductus Thoracicus Dexter,)
as it is called, but more properly the Right Brachio-cepha-
lic, after the name given by M. Chaussier to the vein, is not
more than an inch long, and  descends to empty itself, as men-
tioned,  into the junction of the right internal jugular with
the right subclavian  vein.  It is deiived  from the lympha-
tic trunks of the right side  of the head and neck, from the
right upper extremity, the superficial lymphatics of the right
side  of the thorax, the lymphatics of the  right lung, of the
right side of the diaphragm, and some of those of the right
side of  the liver, the courses of all of which have been de-
tailed.
  Though the single trunk  is formed from these several tri-
butary streams, yet the latter have  sometimes several em-
bouchures into the venous system at or near the point men-
tioned, and, as on the other side of the body, there is  a pro-
per security by valves from the introduction of blood into
them.
  There is always an ample system of anastomosis, not only
between the branches which  concur to form the right and
left thoracic ducts, but even between the ducts themselves,*
so that if one be occluded or impeded, its circulation can be
turned into the other, as in the case of veins.
* Meckel, Man. D'Anat. tom.ii. p. 581. 
BOOK  IX.
                    NERVOUS SYSTEM

                        PART I.

    On the General Anatomy of the JVervous System.

   The nervous system in man, and other vertebrated ani-
 mals, consists  in two portions of dissimilar  forms:  one is
 spheroidal,  elongated at its base into a cylindrical process,
 and is contained in the cranium and in the spinal canal; the
 other  is an assemblage of arborescent rays, which proceed
 from different  points of the  first portion,  to every part of
 the body.  The first portion is the Central or Internal part
 of the nervous  system, composed of the  Brain and Spinal
 Marrow, while the radiating portion is called the External
 or Peripheral,  and  consists in the Nerves of  the brain and
 spinal marrow.
   The  nervous system is remarkable for its symmetry; as
 it is  universally double, it very seldom happens that  any
 striking difference of it on the two sides of the body is ma-
 nifested, particularly as regards its  Central  portion; it is
 said, however,  that  aberrations, in this respect, are more
 common in man than in other mammiferous animals.

  The Central  Portion of the Nervous System is composed
 of two kinds of substance, distinguished by their colour and
 relative situation: one is improperly enough called Medul-
lary (Substantia Medullaris) but as the name is now sanc-
tioned by universal usage, it is impossible  to dispense with
it.  The other is called Cineritious (Substantia Cinerea,)
with perhaps sufficient propriety, from its colour.  They are
both of a soft pulpy consistence, and constitute the chief
mass of the brain and spinal marrow: some anatomists have
  Vol.  II.—40 
314
NERVOUS SYSTEM.
desired to add, from some slight distinction  of  colour, two
other substances, a yellow and a black, but  that seems un-
necessary,  and  has not been  acknowledged.   These  sub-
stances differ from  one  another in regard to  their quantity,
the medullary being more abundant than the cineritious; it
is also harder, and  receives fewer vessels.  But the atoms of
both have the same elementary form, that of  globules united
by a  semi-fluid substance; the shape of these  globules,  as
well as their size and degree of solidity, are not yet ascer-
tained.*

  The Medullary Matter, when quite fresh and scraped  in
particular directions, has a fibrous appearance, which  may
be rendered still more distinct by hardening it in alcohol,
in boiling oil, in a  solution of the neutral salts, or in diluted
mineral acids.  If an attempt be then made to tear it, it will
be immediately perceived that the fibres separate in a fixed
direction, and in no other.  These fibres, when viewed  with
a microscope, seem to consist of fibrillae too  fine to admit of
any rigid conclusions  in  regard to  their size,  and which
are, in some instances, parallel, in  others,  concentric, and
in others, diverging or converging, t
   The two substances are variously placed in different  parts
of the nervous system: the surface of the cerebrum and of
the cerebellum is formed  by the cineritious matter, and the
interior principally of  medullary; while the surface of the
pons, of the crura, and of the spinal marrow, is medullary,
and their interior cineritious.  Again, in other  points,  they
are intermixed. The medullary matter is always so arranged
that it is never interrupted, but forms a continuous whole;
while the cineritious is in detached masses,  and is found
wherever the central extremities of the nerves are implanted,
or where there is  an increase of medullary fibres.   Some
anatomists  have even  supposed that it existed at the  peri-

  * Sir Evd. Home and Mr.  Bauer, Phil. Transactions.  London, An. 1821.
 Milne Edwards, Thesis on the Elementary Tissues of Animals. Paris, 1823.
  ■J- See Lessons on Practical Anatomy, by W. E. Horner. Brain according
to Gall and Spurzheim. 
      GENERAL ANATOMY OF THE NERVOUS SYSTEM-   315

pheral extremities of the nerves, and particularly in the rete
mucosum of the skin.
  The fibrillae of the medullary tissue are united by a very
fine and thin cellular substance, which may be seen by tear-
ing them apart.  This  cellular substance is more condensed
near the surface of the brain, where it is formed into a highly
vascular  membrane, the pia mater, and is continued along
the nerves as a neurileme, or covering to them.
  The central nervous system is abundantly supplied with
blood vessels, but lymphatic trunks have not yet been in-
jected in it.

  The Peripheral Portion of the Nervous System or the
Nerves,  are formed by parallel fasciculi of fibres, percepti-
ble to simple inspection, which may be reduced into fibrillae,
and then again into filaments as small as the thread of a silk
worm.   The finest filament is enclosed  in its appropriate
sheath, so that the latter is a tube filled with nervous matter.
The nervous matter is soluble in an alkali, and in that way
may be removed; the canals may then be filled with quick-
silver or air, and  their existence demonstrated.  On the
other hand, nitric or muriatic acid  dissolves the sheath, but
hardens  the nervous matter, and renders it more distinct, so
that the  finest filaments are made obvious.*  In either case
it is evident that the shape of the nerve is preserved. These
filaments are supposed to be precisely the same with the
fibres of the brain, excepting that their sheaths keep  them
more distinct from one another.
  The Sheath of the nerves, or the Neurileme (Neurilemma)
forms a general envelope  to the nervous fasciculi, as well as
a particular one to each fibre, and is continuous,  at its cen-
tral extremity,  with the  pia mater.  Its canals branch off
and unite again at intervals, forming a species of reciprocal
anastomosis, sufficiently represented by the plan of the large
nervous plexuses, as they  occur in various parts of the body.
It is the general envelope which is obviously continuous with
the pia mater, but  the particular sheaths of the finer fibres
Reil, de Struct. Ncrv. 
316                NERVOUS  SYSTEM.
are lost insensibly, so that these fibres appear naked in the
centre of the  nerve, at its  central extremity.  The same
destitution of neurilematic covering is observable at the pe-
ripheral extremities of the nerves, wherever the latter can
be traced.  The interior of these canals is traversed by pro-
cesses, which cross the nervous matter and sustain it. From
the increase in  size, the  additional solidity, and the close
adhesion of the nerves to the dura mater, where they pass
out of their several foramina in the spine and cranium, there
is no doubt that the dura mater contributes to the neurileme,
though its structure is altered  and made much less dense.
The best evidence of this is the sheath  of the optic nerve,
and of the spinal  nerves.   This  opinion, advanced by the
ancients, has been  strongly contested by Haller,*  and by
Zinn.t  The tunica arachnoidea is too fine to admit of any
positive  opinion about the extent to which it  follows the
nerves.
  The neurileme  has but little contractility, is solid and
difficult to tear,  and is supposed to be the secretory organ
of the medullary substance.
  The nervous fasciculi are moreover held together by cel-
lular  substance,  which has in the progress of life, a tenden-
cy to the deposite  of fat.   This cellular substance, in neu-
ralgic affections, is subject to infiltrations  and redness,
whereby it becomes hard.  This circumstance has  induced
pathologists to consider the pain as depending upon its in-
flammation. J
   The optic nerve, owing to the size of its canals, furnishes
the best example of structure, and the  nerves of the mus-
cles are  next.   There are,  however, some  peculiarities in
different nerves; as the observations of Sir Everard Home
have  ascertained that the medullary  filaments of the optic
nerve augment  in  numbers and diminish in volume, from
its  origin towards its termination.   The  principal  light
thrown upon these minute and interesting points of nervous
organization, has been derived from the researches of Reil.§

  * Prim. Lin.                 f Mcmoires de Berlin, 1753.
  $ Beclard, Anat. Gen. p. 665.
  | Reil, de Structura Nervorum. Halae Saxonum, 1796. 
      GENERAL ANATOMY OF THE NERVOUS SYSTEM.    317

  In addition to the preceding structure, the nerves present
a satin-like undulated  surface,  with small bands that pass
somewhat  spirally and in a zig zag direction.   The latter
appearance is illusory, and depends upon the contraction or
shortening of the nerve  when  not  stretched;  its seat is in
the neurileme,  and it accordingly  disappears  upon exten-
sion.
  The nerves abound in blood vessels;  when  a vascular
trunk reaches them, one of its  branches ascends and ano-
ther descends, and if successfully injected, the neurileme
is covered by its  capillary ramifications.  As  in the brain,
the lymphatics have not yet been injected.
  There are three modes by which the nervous fasciculi
unite with one another;  anastomosis; plexus, and ganglion.
Anastomosis is the junction of  the filaments,  either  of the
same nerve or of different  nerves, and the examples of if;
are very abundant.   Plexus is  an  anastomosis  on a larger
scale, and  occurs between  the  larger fasciculi of the same
nerve, or of different nerves, whereby a very complete in-
tertexture of their fibres  occurs. Ganglions are knots which
occur in the course of nerves, whereby they  have, for the
time, a great augmentation  of volume.
   The  Ganglions have  a great variety of form and  size:
they are parabolic, circular, crescentic, and so  on; and,  in
their general appearance,  hardness, and colour,  resemble
somewhat lymphatic glands.   Their structure is intricate,
and as yet rather ursettled.  When submitted  to macera-
tion, they  are resolved into two kinds  of substance; one is
filamentous and continuous with the  nerves adhering to the
ganglion, and the other  is  gelatinous and of  a reddish ash
colour.   The filaments,  in penetrating the ganglions, are
deprived of their neurileme, which is continued into a sort
of capsule that surrounds the ganglions.  They pass unin-
terruptedly through  the ganglion, and therefore continue
the several nervous cords into one another; but in a compli-
cated way.   The nature of the gelatinous substance is not
fully ascertained; by some, and Scarpa among others, it is
thought to be fat.   The ganglions,  like other parts of the
nervous system, are very vascular. 
318
NERVOUS SYSTEM.
  The Ganglions are said to be simple and compound; the
first is where a single nerve produces the ganglion, and the
second where the filaments of two or more nerves concur
to form it.  The simple ganglions  are  invariable in  their
form and  situation, and belong to  the spinal marrow, being
formed upon the posterior fasciculi alone: this fact was first
pointed out by Haase,* and has been subsequently confirmed
by the observations of Scarpa and  of Prochaska, and by the
admission of anatomists generally.   Their exterior enve-
lope is continuous with the dura  mater, and the internal
with the pia mater, from whence  they have more firmness
than other ganglions.  The composite ganglions are found
at divers stations about the body.

  The Nervous System is the seat of intelligence, and also
extends its  physical influence to  every part  of the body.
Both the  one  and the other qualities reside  in its central
portion; the first in the brain, and the second in  the spinal
marrow.   When the communication between  the brain and
the  spinal marrow is interrupted by an accident, or in an
experiment, the difference between the influence of the two
is strongly marked:! the influence of  the brain seeming to
be entirely intellectual, so that an  animal will even bear its
removal without immediate  death;  while the influence o*
the spinal marrow is so  indispensable to life, that  its de-
struction is  followed by instantaneous and  perfect death.!
Under common healthful circumstances,  however, the two
seem to exercise a mixed influence on all parts of the body;
as, for example, upon  the reception of  distressing intelli-
gence, the stomach ejects its contents, or refuses to receive
more; alarming intelligence  causes the heart  to flutter and
to palpitate, and both the bladder and the intestines to eva-
cuate their contents.  On the contrary,  a proper degree of
corporeal  exertion strengthens the intellectual operations,
while its excess debilitates them.   That these several ner-
  * De Gangliis Nervorum.  Leipsick, 1772.
  f Legallois on the Principle of Life.
  * Observ. and Exper. on the Nervous System, by W. E. Horner.  See
Chapman's Med. and Phys. Journal, vol. i.  p. 285. 
      GENERAL ANATOMY OF THE NERVOUS SYSTEM.   319

vous influences are seated in the central part of the nervous
system, seems proved by the fact, that where there has been
a congenital deficiency of all the limbs, or an accidental one,
which, of course, removes a very considerable portion of
the peripheral part of the nervous system,  animal  life and
the intellectual operations have still  gone on vigorously.
   The following are some of the physical  functions over
which the nervous system seems to  preside.
   Digestion; the whole alimentary canal from the mouth to
the anus, is under this influence: first of all in  mastication,
then in swallowing, afterwards in digestion and the absorp-
tion of chyle, and finally in the passing of the  effete matter
out of the body.   It has  been sufficiently proved, by the
experiments of several physiologists, that the section of the
par vagum destroys the  faculty of digestion.
   Respiration; the  mechanical act  of this process, that by
which the cavity of the thorax is enlarged so as to  admit of
the introduction of air, evidently depends upon the phrenic
and the  intercostal nerves.   If also the nerves which sup-
ply the structure of the lungs be alone intercepted, as the
par vagum, either by ligature or section,  the changes  on
the  blood produced by respiration cease  and the animal
dies.
   Secretion, exhalation, absorption, and animal heat, seem
also to be dependent upon the integrity and the activity of
nervous influence.  The action of the heart, sensation,  and
voluntary motion, are in the same predicament.
   The manner in which these several kinds of innervation
is produced, is unintelligible    One has supposed it to con-
sist  in a vibration of the  elementary fibres of the nerves;
another  in an agitation of its elastic globules; another in the
transmission of an imponderable fluid, as aether, magnetism,
electricity, and galvanism. Reil has proposed, on  this sub-
ject, what has been  termed a chemico-vital hypothesis:  ac-
cording  to him, the general  action of parts depends upon
their form a^d  composition;  consequently, when  the  two
latter vary, the first does also.   M. Beclard* inclines to
Anat. Gen. 
320
NERVOUS SYSTEM.
 the opinion, that " the nervous system is the elaborator and
 conductor of an imponderable agent; and like electricity or
 magnetism,  that by it  we can explain all the phenomena of
 innervation;—The relation between  the  benumbing influ-
 ence of electric fish and galvanic phenomena on one part,
 and ordinary nervous action on the other;—The practicabili-
 ty of causing galvanic phenomena by the nerves and muscles
 alone;—The possibility of producing muscular contraction,
 the chymifiant action of the stomach,  the respiratory action
 of the lung, &c.  in substituting a galvanic for a nervous in-
 fluence;—The existence of a nervous atmosphere, acting at
 a distance around  the nerves and muscles, and between the
 ends of divided nerves;—The wrinkling of muscular fibres
 in contraction, and the relation of the finest transverse ner-
 vous fibres with  those  wrinkles; phenomena of innervation
 which nearly approach certain electro-magnetical ones."
   This subtle  fluid, according to M.  Beclard, seems to be
 formed every where, but principally in places where there
 is much vascularity along with the  ash-coloured  substance.
 It impregnates all the humours  and  organs.   The  blood
 seems to be especially  endowed with it, and owes to it the
 properties which  distinguish  it  during  life.    In  conse-
 quence of which,  life is essentially connected  to the recip-
 rocal action of the blood upon the nervous substance,  and of
 the nervous substance upon the blood.*
   Mr. Charles Bell, of London,  has lately presented  in a
 very interesting light certain functions of  the nervous  sys-
 tem :t by his researches it appears,  that besides the nerves
 of vision, smell,  and hearing, there are four other systems,
 having different functions, and extended through the  whole
frame.   Those of Sensation; of Voluntary Motion; of Re-

  * M. Rolando (Saggio sulla vera struttura del cervello, e sopra le fun-
zioni del sistema nervoso, 1809, Beclard, p. 622.) has been so much taken
with the galvanic manifestations of the nervous system, that in the lami-
nated arrangement of the cerebellum he has only seen a modification of the
Voltaic pile.  In the convolutions of the cerebrum, he, no doubt, would
have recognised, on acquaintance with this powerful instrument, the Spi-
ral Calorimotor of Professor Hare of this University.
  f Exposition of  the Natural System of the Nerves of the Human Body.
Philad, 1825. 
       GENERAL ANATOMY OF THE NERVOUS SYSTEM.   321

spiratory Motion; and nerves, which give unity to the body
in harmonizing the functions of nutrition,  growth, and de-
cay, or whatever else is indispensable to animal existence.
   According to this theory, the several filaments of a nerve
exercise one or the other function, but only the one; these
dissimilar filaments being bound up  in the same fasciculus,
constitute a nerve or fascis, and  they never exchange power
with one  another: their anatomical differences, however,
are such, as not to make obvious one kind of filaments from
the others. Several columns of nervous matter form the spi-
nal marrow, six in all, three on each side; the anterior for
voluntary motion,  the posterior for sensation, and the mid-
dle for respiration;  and it is probable that still more may
be found out.   The first and the third ascend into the brain,
and the middle stops short in the medulla  oblongata, hence
the function of respiration goes on  so  long as the medulla
oblongata remains entire.   These few principles, supported
by several experiments, have enabled Mr.  Bell to bring for-
ward a system of no small importance on  the anatomy and
physiology of the nervous system. *
   The development of the  nervous system is amongst the
earliest processes  in the distinct evolution of the  fcetal or-
gans, t   At the end of the first month,  when the  head is a
mere swelling of one end of the small  maggot-like  being,
the brain and the spinal marrow are not by any means dis-
tinct,  but the parts being  transparent, a limpid fluid holds
their place.   About the fifth or sixth  week,  the embryo
having acquired a length of five or six lines, the rudiments
of the brain appear as vesicles containing a whitish and al-
most diaphanous fluid, while the spinal  marrow represents
a long canal containing the same, and communicating with
the cerebral vesicles.

  * The same subject has been taken up, in an inaugural thesis, by a zea-
lous and intelligent graduate of the University, and, by a series of inge-
nious experiments, seems to have been generally proved and illustrated.
Chapman's Med. and Phys. Journal, 1823, vol. vi. p. 240, Remarks on some
of the Nervous Functions, by J. P. Hopkinson.
  f Anat. du Cerveau, par F. Tiedemann, traduit par Jourdan, Paris, 1823.
Anat. Comp. du Cerveau, par E. R. A. Serres, Paris,  1824,
  Vol. II.—41 
322
NERVOUS SYSTEM.
   In the early part of the third month, when the embryo
is about twelve lines long, the brain and spinal marrow be-
gin  to  show very distinctly the  rudiments of the  several
cavities, elevations, and fasciculi, which  mark their subse-
quent mechanical arrangement of surface; and from  this pe-
riod it is no longer difficult to trace the successive develop-
ment of each part to the degree of  perfection which it has
at the time of birth.
   From the many observations  made by Tiedemann on
these points, he has deduced the conclusion, that the brain
is produced by the superior part of the spinal marrow, that
is to say, by the medulla oblongata, which grows and is de-
veloped for the purpose.   That this is proved,  in  the ex-
tension upwards and forwards of the two principal fasciculi
of the spinal marrow, and by a canal which is found in the
spinal marrow of the foetus, being  extended to  the fourth
and  even to the  third ventricle; also, by the  cerebellum
proceeding evidently from the same source, since  its two
crura may  be traced  growing from it, and  subsequently
uniting over the fourth ventricle, so as  to form the especial
structure of the cerebellum;  also, by the tubercula quadri-
gemina being derived from the corpora olivaria of the me-
dulla oblongata, and by the thalami and the corpora striata
proceeding from the corpora pyramidalia, and finally forming
the hemispheres of the cerebrum.
   In addition to the preceding proofs, comparative anatomy
furnishes other illustrations.  The brain becomes more and
more complex as one ascends from fish  to reptiles, from
the latter to birds, and then to mammiferous animals. The
spinal marrow is very voluminous in the  inferior animals,
while the brain only forms an appendix to it; whereas, if
the spinal marrow were an appendix to the brain, we ought
to find  the last of a prior formation  in  foetuses, and  also in
a perfect state in the lower animals, before a medulla spi-
nalis could  be found.*
* Tiedeman, loc. cit. p. 157. 
BOOK IX.
                       PART II.


On the  Special Anatomy of  the Central Portion of the
                   Nervous System.


                    CHAPTER  I.

     OF THE SPINAL MARROW AND ITS MEMBRANES.

   The  Spinal  Marrow (Medulla  Spinalis)  though com-
monly described after the brain, as a continuation or appen-
dage of it, has precedence, as seen both in  the period of
its formation in the embryo, and  in  its importance to the
functions of the animal system; it will consequently be use-
ful to give it that priority in description to which its natu-
ral rank entitles it.

           SECT. I.—OF THE SPINAL MARROW.

   It is placed within the vertebral  cavity, and extends from
the first vertebra of the neck to the first or second vertebra
of the loins inclusively.  It is surrounded by three mem-
branes,  of which the Dura Mater is external, the Pia Mater
internal, and the Tunica Arachnoidea, between the other
two.   Its general form is cylindrical, yet it has slightly the
appearance of being flattened both behind and before.   It
departs also from the strict  cylindrical shape by being en-
larged or swollen at particular  points.   One of these en-
largements occurs in the neck, where the canal is formed 
324
NERVOUS SYSTEM.
by the five lower cervical vertebrae and the axillary plexus
of nerves is given off.   The enlargement is in the transverse
direction or axis of the spinal marrow, but not in its thick-
ness,  and  terminates  gradually  both above  and  below.
The medulla-spinalis afterwards continues small, with very
slight undulations  or nodosities, until within three or four
inches of its lower extremity, when it again enlarges. The
enlargement here, though sufficiently obvious, is not equal
in actual magnitude to that  in the neck, and  is the place
from which all the lumbar nerves and the three superior
sacral  proceed.   It is  then   brought  gradually  to  a point
somewhat blunted, which most commonly does not descend
below the first lumbar vertebra.   The point is in some rare
cases bifurcated, and by  a transverse  fissure converted into
a tubercle.
  The spinal  marrow, besides terminating so much above
the lower end  of the spinal canal, is much smaller in  its dia-
meter, even with the addition of its  membranes, than the
canal.   This circumstance  prevails especially in the neck,
and in the  loins, where much motion is  experienced; and
consequently a provision is thus made against any injury to
it from pressure.

  The  Medulla Spinalis is  marked  off  longitudinally into
two symmetrical parts by one fissure in front and another
behind, both  of  which  extend its whole length,  and  are
placed exactly in its middle.  The contiguous edges or sur-
faces of each  of these  fissures adhere so, that it requires a
slight maceration or dissection to render them evident.  The
posterior fissure is decidedly deeper at its upper part than
the anterior, but the latter in return is somewhat broader.
The difference in depth, however, is unimportant,  as sub-
jects are frequently met  with in which it is not appreciable.
   Moreover,  on each side of the Medulla Spinalis there is a
lateral fissure.  It is not precisely in the middle, but some-
 what posterior, and penetrates inwirds and forwards.   In
 many instances it is merely  a simple superficial depression,
 much less deep than either of the former.   It does not run 
SPINAL MARROW.
325
the whole length of the medulla spinalis, but terminates
somewhere in the upper part of its thoracic portion by join-
ing with its ft-llow, after having converged regularly towards
it. "   The different opinions of anatomists on the existence
of these two fissures may be accounted  for  by their  being
readily found  in  early  life, while they are obliterated or
very indistinct in old age.  These lateral fissures should be
carefully  distinguished from two others, also on either side,
one before and the other behind, which extend the whole
length of the medulla spinalis,  and consist in a series of little
depressions, running  into each other and  transmitting the
filaments which  form  the roots of the spinal nerves.   The
posterior, of  the last  named lateral fissures, is deeper than
the anterior,  and penetrates in the same direction with the
lateral  fissures first mentioned; it also in like manner joins
its fellow, but only after having proceeded to within a few
lines of the inferior end of the medulla spinalis.
   The substance of the spinal marrow  being of two  kinds,
cineritious and medullary, the order of their position is re-
 versed from what occurs in the brain; for the cineritious  is
included or enveloped by the other.  On making a transverse
 section the cineritious will be found much less abundant than
 the other, and consisting of a thin transverse part in or near
 the centre of the medulla.   This part is joined at either end
 to a portion  somewhat  crescentic, whose  concavity is out-
 wards, and the convexity inwards.   The transverse  part
 does not run into the middle of the crescent,  but somewhat
 anterior  to the middle,  so that the anterior  horn  is shorter
 than the other, and is also thicker and  more obtuse, having
 its end covered by medullary matter, while the remainder
 is not.   The cineritious or grayish substance is more abun-
 dant at the lower part of the medulla spinalis than it is above.
 In the foetus, at the end of gestation, it predominates  below,
 occasionally to the entire exclusion of the other.   The me-
 dullary or white substance is more  abundant laterally than
 elsewhere, and has  its two symmetrical sides joined together
 by a th'.n lamina at the bottom of the anterior and of the
 posterior fissure.
* Meckel, Manuel D'Anatomic. 
326
NERVOUS SYSTEM.
   Each half or symmetrical side of the medulla spinalis is
 itself divided into two chords, marked off from each other
 by the posterior horn of the cineritious crescent, and by the
 intermediate  lateral fissure.   Of these chords  the anterior
 is, consequently, much  the larger; it is also longer  and
 forms the inferior extremity or the point of the medulla spi-
 nalis. The posterior chord, though so much smaller and nar-
 rower, than the anterior, is itself subdivided into two, by a
 slight but well marked fissure; of the two last chords the one
 next to the posterior middle fissure of the medulla is smaller
 than the other.   These arrangements, according to Meckel,
 are much more obvious in the early life of the human sub-
ject,  than afterwards, and are particularly conspicuous in
 the brute creation.
   The thin  white laminae by which the two sides of the spi-
 nal marrow adhere to each other at the bottom of the mid-
 dle fissures, are called, by modern anatomists, Anterior and
 Posterior Commissures.   Their precise arrangement is not
yet  fully ascertained,  but it is stated  by Gall and Spur-
zheim* that the Anterior Commissure is formed by trans-
verse fibres or filaments, which adhere to one another from
the opposite sides like a suture, or  after a serrated fashion;
whereas the Posterior Commissure is formed by a band of
longitudinal fibres.   There  is also another  Commissure,
called Middle or Cortical, from its position and  from its
being formed  out of the transverse part of the grayish sub-
stance.
   The chords which form each half of the medulla are diffe-
rently disposed, the posterior continues on the side to which
it specially belongs, while the anterior having  got  within
the circumference of the first cervical vertebra crosses over
to the opposite side by decussating with  its fellow.   This
decussation occupies the space of four or five lines, and in-
terrupts, for that distance, the middle fissure on front of the
medulla.  It is not effected by the  chords passing in mass
from one side  to the  other, but each chord sends off four
or five fasciculi, which are interwoven with their congeners
like the fingers of the two hands when interlocked oblique-

  * Recherches surle Syst. Nerv. et sur ce lui du Cerveau.  Paris, 1809. 
SPINAL MARROW.                327
ly. It is to be observed that the whole mass of the anterior
chords is not subjected to such distribution; for the^fasciculi
just described come from their anterior and from their pos-
terior faces, the middle part being permitted to pursue their
course straight upwards.   This decussation, upon which so
much interesting physiological speculation depends,  though
known for the last century, and spoken of by Mistichelli and
Petit,  has  been strangely overlooked by many anatomists,
and is even positively denied  by some.   There are other
places where the fasciculi of the spinal marrow seem to cross
from one side to the other, but the fact is not yet verified.
   The  existence  of canals in the spinal marrow has been
from time to time announced;* though authors differ much
in the accounts of their position and extent.  When  such an
appearance is presented, it is supposed, by some, to be either
the result  of disease or of accident, with the exception of a
small one  of eight or nine lines long, which communicates
at one end with  a fourth  ventricle, and is shut  up at the
other.t
   The  Spinal Marrow sends out from its sides thirty pairs
of Nerves, which, like the vertebrae, are arranged into cer-
vical,  dorsal, or  thoracic, lumbar, and sacral.  Of these
there are eight cervical, one of which, from its escaping be-
tween the occiput  and the first  vertebra, is most  usually
designated as suboccipital, and,  therefore, the number of
the cervical nerves  is reduced to the same with that of the
vertebrae,  to wit,  seven.   There  are twelve pairs of dorsal
nerves, five of lumbar, and five of sacral.  Occasionally there
is a sixth  sacral  nerve on  each side, which augments the
number of spinal nerves to thirty-one pairs.
   Every spinal nerve is formed from two roots on the same
level, one  before and the other behind,  and each root con-
sists in several fasciculi of nervous matter.  The front root
arises from the anterior chord of  the medulla spinalis,  and
the other from the posterior chord.   The posterior root is
larger than the anterior, but has fewer fasciculi in its com-

  * Gall, Portal, Morgagni.
  t Meckel, p. 605, vol. II. Bichat, vol. 1U. p. 128. 
S28
NERVOUS SYSTEM.
position, and is not so filamentous.  The two roots are kept
asunder by the  Ligamentum Denticulatum.  The fasciculi of
each are slightly  connected by a loose delicate cellular sub-
stance, and as they are about penetrating the dura mater, each
fasciculus collects into a single chord, which passes the dura
mater  through its appropriate foramen.   In this way the
anterior and posterior roots are kept distinct till they have
got to the outside of  the membrane mentioned;  but the fo-
ramina  through which they pass border closely upon  one
another.  The posterior root, then  forms a ganglion of a
round or oval shape,  from  whose external  extremity there
proceeds a single nervous trunk, which is joined  immedi-
ately at its commencement by the anterior root.
   With the exception of the ganglions of the sacrum, which
are in the spinal cavity of  that bone, these bodies are
placed in the intervertebral foramina.  The size of the gan-
glion is not proportionate to that of the nerve from which
it proceeds; for some  of the dorsal ganglions are the largest,
while those of the sacrum are smaller than any others.
   The two nerves of  the same pair, though generally sym-
metrical  or precisely resembling, are  not invariably so;
sometimes one  is  placed higher than another, and the num-
ber of  the  fasciculi may  be greater or smaller.   The roots
of the  nerves are much  nearer,  or cluster more at the ex-
tremities of the spinal marrow,  than  in its middle.  The
lumbar and sacral nerves are  indeed so close together and
so much in a bunch, that the arrangement is designated by
the term Cauda Equina.

   The Cervical Pairs of Nerves are  nearly horizontal in
their course from the  medulla spinalis  to  the foramina in
the dura mater.   The first one, or the sub-occipital, is
strictly so; the others  incline very gradually more and more
downwards.  They have, therefore, but a very short pas-
sage before they reach the  intervertebral foramina.  Their
roots are  so  pyramidal,  that  the bases nearly touch  each
other, and, for  the most part,  are connected by an anasto-
mosing filament,  which goes from the upper margin of the
root below to the  lower margin of the  root above.  These 
          MEMBRANES OF THE SPINAL MARROW.       329

anastomoses are found connecting the upper with the lower
fasciculi, both on the anterior  and  posterior chords of the
medulla, but more uniformly as regards the latter.  Modi-
fications of this arrangement, which it is unnecessary to
specify, are met with in different subjects.
  The Dorsal,  or Thoracic Pairs, are much inferior in size
to any  others, except the inferior  sacral.   Anastomosing
filaments do not generally prevail, yet they are found occa-
sionally, as in the neck,  upon the two or three upper pairs.
The first one has the broad pyramidal or triangular root of
a cervical  nerve, and resembles it  also in volume.   The
second  is the  smallest of any; they then go on increasing
in  size to  the lowest,  but not in  a uniform gradation.
They  are  successively  more  oblique, and  consequently
longer from their bases to their passage through  the dura
mater.
   The  Lumbar and the Sacral Pairs arise  close upon each
other, indeed  in absolute contact  successively,  from  the
lower enlargement of the medulla spinalis.   As their place
of origin is within the precincts of  the first lumbar verte-
bra and the two or three last dorsal, they all observe a very
oblique course in their  descent to  the vertebral foramina,
and the lower ones are almost vertical.  Notwithstanding,
they are in contact and adhere  by a loose cellular substance,
yet there are no  anastomosing filaments between  the adja-
cent roots.   From the sacral  ganglions presenting the pe-
culiarity of being situated in  the spinal  cavity of the sa-
crum,  instead  of in the foramina, the single nerve formed
from the ganglion and the anterior  fasciculus, has to  pro-
ceed a distance more or less  considerable  in the spinal ca-
vity before it can escape from it.


       SECT. II.--MEMBRANES OF SPINAL MARROW.

     Of the Dura  Mater of  the Medulla Spinalis.

  This  membrane,  forming the exterior envelope of the
spinal marrow,  extends from one end of the spinal canal to
  Vol.  II.—42 
330
NERVOUS SYSTEM.
the  other, being  continuous  above with  the dura mater
of the  brain,  and terminating below in  a cul-de-sac  or
closed extremity.   It does not adhere to the surface of the
spinal canal,  but lies loosely attached to it, with the excep-
tion  of the first cervical vertebra, to which it is closely fas-
tened.  Between it, and the  ligaments and  periosteum on
this  surface of the bones of the spine, is a long, loose, and
spare cellular substance,  generally somewhat  watery, and
containing in the lumbar and sacral regions,  a reddish adi-
pose matter.  This membrane is so much larger than the me-
dulla, that it invests it very loosely and always presents a
collapsed appearance.
  Where the nerves  penetrate, it furnishes  to each one, a
sheath as far as the intervertebral foramen.   Those sheaths
are longer for the cauda equina than elsewhere,  and,  of
course,  observe the  same successive obliquity with the
nerves to which they belong.   Having reached the inter-
vertebral  foramina, they enlarge so as to enclose the  gan-
glions, adhere by cellular substance to  the contiguous peri-
osteum, and  are  then insensibly lost  in the tunics of the
nervous trunks.   The internal surface  of the dura mater is
smooth and shining, which is probably owing to the tunica
arachnoideae being reflected over it.    This membrane has
a fibrous texture,  and, with  inconsiderable  exceptions,  is
like  that of the brain.


 Of the Tunica Arachnoidea of the Medulla Spinalis.

  This membrane is next to  the dura mater, and is easily
distinguished by its extreme delicacy,  thinness, and  almost
perfect transparency.   It is destitute of red  blood vessels.
It forms, also, a complete envelope for the medulla spina-
lis, and adheres to it  only very loosely by means of long,
slender, and  scattered filaments of cellular substance.   If
the dura mater be slit up its whole length before and be-
hind, and a blow-pipe be introduced at one end of the me-
dulla, between the pia mater  and the arachnoidea, inflation
will  cause the latter to rise, and to present itself as a  long 
MEMBRANES OF THE SPINAL MARROW.
331
capacious tube, detaching on each side processes which sur-
round  the  roots of the nerves.  These processes  having
reached the points where the nerves penetrate the dura
mater, are  then reflected upon its internal face, and are sup-
posed to give  it the glistening appearance.   The processes
enclosing the  fasciculi of the spinal nerves, are particularly
conspicuous about the Cauda Equina.


       Of the Pia Mater of the Medulla Spinalis.

   This third  envelope of the  spinal marrow forms also  a
complete investment of the latter, and adheres very closely
to it.   Its external face  is smooth, and is in contact with
the arachnoidea, from which it may be readily separated by
inflating the  latter.   But from  the middle of its internal
face both anteriorly and  posteriorly, a process or partition
penetrates into the middle  fissures of the medulla  spinalis,
and reaches to their bottoms.  From these partitions there
proceed a  great number of small vascular  canals, that pass
in various directions through the medulla, and anastomose
 freely with each other.   This arrangement is rendered suf-
 ficiently obvious  by  injection, and then destroying the me-
 dulla in an alkaline solution; or if the medulla be hardened
 by  neutral salts or acids, it splits into longitudinal laminae,
 divisible into chords, whereby the arrangement  is made
 equally manifest.  A fact of some consequence is thus es-
 tablished,  to  wit, the similitude between the structure  of a
 nerve and of the medulla spinalis.
   At the inferior end of the medulla the pia mater becomes
 a single chord, which is continued among the cluster  of
 nerves, to the lower end of the  tube  formed by  the dura
 mater, and there it joins with the latter.  As a membrane,
 the pia mater is much more complete than the correspond-
 ing one of the brain, has more  strength, but is not so  vas
 cular.   Its thickness increases  in  its descent.  It is  of a
 yellowish-white  colour.   It  seems  to  hold the medulla
 somewhat in  a state  of compression, for when a puncture is
 made through it,  the medullary substance protrudes like a 
332
NERVOUS SYSTEM.
hernia.  It goes from the medulla to the fasciculi of nerves,
and forms their neurileme or sheath.


             Of the Ligamenta Denticula.

  These bodies are narrow semitransparent bands, and very
thin, which are placed one on  either side of the medulla
spinalis, between the pia mater and the tunica arachnoidea.
They commence  at  the  occipital foramen, and descending
between the anterior  and the posterior fasciculi of nerves,
terminate somewhat  above the inferior extremity of the
medulla.
  Each one is, at its commencement, in front of the acces-
sory nerve, and in  descending is  rather nearer to the pos-
terior than to the anterior fasciculi. By its internal margin
it adheres with uniformity  to  the  pia mater,  but the exter-
nal margin has  a very different arrangement; for it sends off
at intervals from twelve to  twenty-four serrated or denticu-
lated processes, which for the most part are placed between
the fasciculi of cervical and of dorsal nerves.  The extremi-
ties of these teeth  are small, rounded, and strong, are sur-
rounded by the  arachnoidea, and adhere very forcibly to the
dura mater, being  pointed  downwards.  The position and
connexions of each ligamentum denticulatum are such, as
to make it serve as a fastening; which use is additionally
indicated  by its fibrous texture, and  by the  necessity that
the medulla has for  such fastening, in consideration of its
being so deficient in filling up the vertebral canal.
  It is taught by many anatomists, that the ligamenta den-
ticulata, from the opposite  sides, join at  the lower end of
the spinal  marrow to form the single cylindrical chord that
passes thence to the lower end of the spinal cavity, and has
been described  as an emanation from the pia mater.  I am,
however, induced to  think with Meckel and others, that
general  analogy is in favour of the latter. 
      BLOOD VESSELS OF THE MEDULLA SPINALIS.     333


   SECT. III.--OP THE BLOOD VESSELS OP THE MEDULLA
                        SPINALIS.

  The Arteries of the Spinal Marrow are derived from the
Vertebrals, Intercostals, Lumbar, and Sacral Arteries.

   1. The Posterior Spinal Artery (Arteria Spinalis Pos-
terior) is the lowest branch of the vertebral, given off in the
cavity  of  the cranium.  It  reaches, soon after its origin, the
posterior face of the Medulla Spinalis, and runs to the lower
extremity of the latter, on the side of its posterior fissure.
Its course is parallel with  its fellow, and very serpentine.
In  its  descent it is continually re-enforced  by the small
branches which get into the spinal cavity through each of
the intervertebral foramina.

   2. The Anterior Spinal  Artery (Arteria Spinalis Ante-
rior) arises above the last from the vertebral.  Shortly after
its  origin it unites with its fellow into a  common trunk,
which descends  along  the anterior fissure of the medulla
spinalis, but is subject to  interruptions.  It  also is re-en-
forced by twigs from  the  arteries that pass into the spinal
cavity through the intervertebral foramina.  In its whole
course it sends off  branches from each side to the medulla
spinalis.

   The Cauda Equina is supplied by arteries from the Lum-
bar and from the Sacral arteries, which reach it through the
foramina,  between the vertebrae, and in the sacrum.

  The Veins of the Spinal Marrow are very abundant.   A
large one, called the Sinus Columnae Vertebralis, is situated
in the spinal  cavity, on the posterior face of  the bodies  of
the vertebrae, between  their ligamentous covering and the
dura mater.   One of these veins exists on each side of the
middle line.  They detach a considerable number of branches,
which  run transversely, and  anastomose with one another 
334
NERVOUS SYSTEM.
on the body of each vertebra, so that each vertebra has its
little  system of anastomosing branches, called Circelli Ve-
nosi.  These anastomoses communicate with the intercostal
veins, and indeed with all such as are on the outside of the
spinal column,  by means of small branches, that get out  by
the intervertebral  foramina.  They receive  the veins from
the bodies of the vertebrae, and from the dura mater of the
spine.

  The two  sinuses may be traced as low down as the  infe-
rior end of  the sacrum, where they arise by small trunks
from the fatty matter which surrounds the lower end of the
cauda equina.  When their size is somewhat augmented  by
their ascent, they communicate by a large transverse branch.
The superior end of each sinus terminates by several anas-
tomoses with the vertebral vein, and with the anterior occi-
pital sinus, through the latter of which its blood  is finally
carried into the lateral sinus.   For a further account see
Sinus  Vertebrales.
                    CHAPTER II.

            OF THE ENCEPHALON,  OR BRAIN.

  By this term is designated that section of the central por-
tion of the nervous system, which is contained within the
bones of the cranium.  In its general configuration it differs
materially from the medulla spinalis in being spheroidal or
oval.  It is surrounded by the same membranes; to wit, the
Dura Mater externally, the Tunica  Arachnoidea next, and
the Pia Mater internally.

  The Encephalon is formed by cineritious and medullary
matter,  and as a mass  consists of four distinct portions. 
NERVES OF THE ENCEPHALON.           335
The Medulla Oblongata, which is a continuation of the spi-
nal marrow or its superior part; the Protuberantia Annu-
laris or Pons Varolii, which  is  placed at the upper extre-
mity of the Medulla Oblongata; the Cerebrum, which oc-
cupies six  or seven-eighths of  the  cavity of the cranium;
and the Cerebellum, which lies  upon the posterior fossae of
the base of the cranium.  As the brain is a double organ,
each of these parts is symmetrical,  or consists in right and
left halves  perfectly alike.


     SECT.  I.--OF THE MEMBRANES, OF THE  BRAIN OR
                     ENCEPHALON.

                   Of the Dura Mater.

   This membrane, the most exterior of the three belonging
to the encephalon, iines the whole internal face of the cavity
of the cranium, and adheres with great tenacity to its bones,
particularly in early life, from  which cause it is also consi-
dered as an internal periosteum.
   Its external surface has a rough and unequal appearance,
and adheres much more  strongly to the bones where the
sutures exist than  elsewhere, owing to its detaching many
large filaments, which penetrate into the sutures and reach
to the pericranium.  To the surface of the bones it adheres
by very fine filaments of fibres,  and by very numerous and
small blood vessels which become very evident by the dots
of blood seen upon its surface,  when the bones are torn up
from it, as in the usual manner of examining the head. To
the base of the cranium, its adhesion is  unusually strong,
owing to the abundance of the  foramina and fissures there;
to the margin of each one of which it is fixed with extreme
compactness, and may be considered as continuous with the
adjacent pericranium.
  The external surface is marked by the arteries and veins
which creep and ramify through it, and make, as mentioned
elsewhere,  corresponding furrows in the bones. 
336
NERVOUS SYSTEM.
   The Dura Mater consists of two laminae, one within the
 other; they, however, adhere so closely in the greater part
 of their extent, that it requires the knife, or strong artificial
 force to separate them.  Sometimes, in tearing off the skull
 cap of a middle aged person, the external lamina is brought
 away with the bone.
   Several Processes  arise by a duplicature of the internal
 lamina of the dura mater, and extend from the circumference
 towards the centre of the cavity of the cranium.   They are
 as follows:

   The Falx Cerebri separates the hemispheres of the brain,
 and is, consequently, precisely under the middle line of the
 head.  Its shape is well indicated by its name. It commences
 by a small point from the middle of the body of  the sphe-
 noid bone, and continues to arise along the crista galli, the
 spine and middle line of the frontal  bone, the sagittal su-
 ture, and the upper limb of the occipital cross, till it reaches
 the internal occipital protuberance.   It is about an  inch
 broad in front, where it begins,  but it  increases continually
 though gradually in breadth till  its termination, where it is
 two or two and a half inches wide.  It is strongly fastened
 along the  crista galli and at the  foramen coecum,  and being
 also fastened behind to the tentorium (with which it is con-
 tinuous) as well as  along the intermediate points of bone, it
 is kept in a state of strict tension, which does not admit of
 its wavering to one side or to the other.  Its inferior  mar-
 gin is very concave, and goes to within a small distance of
 the corpus callosum.  There are sometimes  considerable
apertures  in it, through which the flat surfaces of the he-
mispheres come in contact.

  The Tentorium Cerebelli, another  process of  the  dura
mater, is placed transversely across the posterior part of the
cranium, and separates the cerebellum from the posterior
lobes of the cerebrum.  It is continuous with the posterior
end of the falx  major,  whereby these two processes ex- 
            MEMBRANES OF THE ENCEPHALON.        337

ercise a mutual tension.   The tentorium is therefore kept
convex above and concave below.
   Its form is crescentic; its outer circumference is extended
along the horizontal limbs of the occipital cross, and along
the superior corner or margin of the  petrous  bones to the
posterior clinoid process.   The internal circumference is
much smaller and unattached, and being placed immediate-
ly behind the sella turcica, it leaves an opening  (the Fora-
men Ovale) which is of nearly the same size with, and occu-
pied by the tuber annulare.   The anterior extremities of the
crescent are continued from  the posterior clinoid process to
the anterior on each side, so that a deep depression is formed
for lodging the pituitary gland.

   The Falx Cerebelli is a small triangular process of the
dura mater, which extends in the middle line from  the un-
der surface of the tentorium to the posterior margin of the
occipital foramen.   Its base is  above  and its point below;
the latter terminates by  a small bifurcation.   It adheres by
its posterior margin to the middle inferior limb of the oc-
cipital cross;  the anterior margin is free, and  serves to se-
parate the two hemispheres  of  the cerebellum.

   The Dura Mater is essentially fibrous, as is sufficiently
evident at whatever point  it  may be  examined.  These
fibres  have no settled course, but cross each other in every
direction.   It is white,  sufficiently transparent for the ves-
sels of the pia mater to be imperfectly seen through it, and
almost inelastic.   Its internal  face is smooth and polished,
and  is presumed  to be covered or lined by the tunica arach-
noidea, the halitus from  which  gives it a slippery feel.   It
is insensible to common excitants, such as cutting, or even
cauterizing it; from which circumstance, together with the
common inability  of  anatomists to  trace  nerves  into its
structure, it is supposed, by many, to be entirely destitute
of them.   The venerable Chaussier, however, takes  a diffe-
rent position in regard to these points, and says, that it has
sensibility, and that though none of the cerebral nerves can
   Vol. II.—43 
33b
NERVOUS SYSTEM.
be traced into it, yet by attentive examination it is found,
that filaments from the sympathetic nerve follow the rami-
fications of its middle or great artery.*
  It is well supplied with  blood vessels,  both arteries and
veins.  The former are derived principally from the branch of
the internal maxillary of either side, which gets into the cra-
nium through the foramen spinale.  There are branches also
from the aethmoidal, the inferior pharyngeal, and the ver-
tebral.  The branch of the internal  maxillary divides into
two, of which  the anterior being the  more  considerable,
gains the anterior and  inferior angle of the parietal bone;
but the other is directed backwards to the squamous por-
tion of the temporal.   Each of these branches is subdivided
into a  considerable number of smaller ones, which  for the
most part incline backwards.  Their capillary terminations
are supposed by Bichat to be in small number comparative-
ly, and to be limited principally to those  of nutrition.
  Some of the veins accompany the arteries, as in other
parts of the body, and empty into the si  uses about the base
of the cranium.   In the case of both  arteries and veins,
there is, however, a very considerable anastomosis with the
blood  vessels of the diploic  structure of  the cranium, and
with those of its integuments.

   Of  the Sinuses of the  Dura Mater.—The sinuses are
large cavities placed between the two  laminae of the dura
mater, and receive the  blood from the veins of the pia ma-
ter   They are formed by the separation  of these laminae,
and are lined by a membrane corresponding with the inter-
nal coat of the veins.

   1. The Sinus Longitudinalis Superior extends along the
whole base of the falx  cerebri,  from the ethmoid  bone to
the tentorium, where it terminates  in  the  lateral  sinuses.
It begins at the foramen coecum in a small pointed manner,
and  according to some anatomists  by a small vein, which

              * Exposition de L'Encephale,  p. 29. 
MEMBRANES OF THE ENCEPHALON.        339
 passes from the nose through this foramen; it is successive-
 ly increased in size from before backwards, and is of a pris-
 matic shape.   One side of the  prism is  upwards, and of
 course is formed by the external lamina of the dura mater;
 while the other two parietes are lateral, and are formed by
 the duplicature of the internal lamina.   Its cavity presents
 a number of small  cords, round or flattened, passing from
 one side  to the other; they are called  Chordae  Willisii or
 Trabeculae, and prevail  principally at its back part.
   The longitudinal sinus receives on each side from ten to
 twelve large veins,  which bring the blood from the pia ma-
 ter.  Those from the convex surface of the brain are joined
 just before entering the sinus  by such as belong to the flat
 side of the hemispheres.  These veins  enter the sinus, for
 the most part, obliquely forwards, or in a manner opposed
 to its circulation.   The most posterior ones previously glide
 eight or  ten lines between the laminae of the dura mater,
 and are  somewhat  tortuous; they are  also furnished with
 valves, which  circumstance, besides their oblique  entrance
 into the  sinus, is a  provision against  their being  filled by
 the regurgitating blood.   This sinus  also receives several
 veins from  the bones, and some  from the  scalp,  which tra-
 verse the bones at different places; among the  largest of
 them are those that come through the parietal foramina.
 The  dura mater itself  sends  some of  its veins into  this
 sinus.
  In  the  longitudinal sinus, towards  its posterior  part, are
 found a considerable but variable number of small  granular
 bodies;  some in clusters, others  insulated; and from  the
 size of a  pin's  head to a line or  more in diameter.   They
 are the Glandulae Pacchioni; they have  no excretory ducts
 that have been discovered, and it is entirely uncertain whe-
 ther any specific fluid is secreted from them.   These bodies
 are also to be found on the surface of the  dura mater near
 the  sinus; some of them indeed make foramina through the
 dura mater, and  corresponding depressions in  the skull.
 One on each side, larger  than usual and near the parietal fo-
ramen, is  remarkable for this. 
340
NERVOUS SYSTEM.
  2. The Sinus Laterales, one on each side, are situated in
the base of the tentorium  and follow its  course  along the
grooves of the occipital and  temporal bones.   They then
leave the tentorium and go along the groove in the mastoid
portion of each temporal bone to reach the posterior fora-
men lacerum, where they terminate in the internal jugular
veins.   Their shape is ovoidal instead of prismatic,  as the
longitudinal sinus is; they are also larger than it.
  The sinus of the right side  is very frequently larger than
that of  the left, and seems to  be more a continuation  of the
superior longitudinal  sinus.    In  some rare cases one  of
these sinuses  is deficient.   The  lateral and inferior  veins
of the cerebrum, and  the inferior veins of the cerebellum
run into the lateral sinuses.

  3. The Sinus  Longitudinalis Inferior is situated in the
falx cerebri just above its concave edge.  It is much smaller
than the superior, and terminates behind in the sinus  quar-
tus.   It receives the veins of the falx, and sometimes a few
from the corresponding parts of the hemispheres.

  4. The Sinus Quartus, or Rectus, is situated in the ten-
torium, where the latter is joined by the falx major or cere-
bri.   It is triangular or prismatic, and runs from the  ante-
rior  margin of  the tentorium to the posterior, where it
terminates in the extremity of the longitudinal sinus.   The
general union which is there  found between the longitudi-
nal, the fourth, and the lateral sinuses, constitutes the Tor-
cular Hierophili.
  The anterior  extremity of  the fourth sinus, besides re-
ceiving the  inferior longitudinal,  is  joined by  the  Vena
Galeni, a single trunk, formed by the junction of the two
veins of the middle of the velum interpositum, and  extend-
ing from the posterior margin  of the fornix to the beginning
of the fourth  sinus.   The latter in its course also receives
the superior veins of the cerebellum,  with the exception of
the most anterior ones, which terminate in the Vena Ga-
leni. 
MEMBRANES OF THE ENCEPHALON.
341
  5. The Sinus Petrosi are small cylindrical  cavities, and
are so called from being  situated  on  the petrous bone.
There are two on each side; one above and the other be-
low.   The former is the  Superior, and runs from the ca-
vernous sinus along the superior margin of the petrous bone
to join the transverse sinus, where  the latter quits the ten-
torium to descend towards the base of the cranium.   The
other Petrous Sinus is the Inferior.  It is larger than  the
superior,  and arises, also,  from the cavernous sinus by its
posterior  margin.  It then runs along the fissure between
the occipital and the petrous bone,  leaving its mark on the
margin of these bones, but principally on the former, and
then  terminates in the lateral sinus just above the posterior
foramen lacerum.

   6.   The  Sinus Cavernosi, one  on  each  side,  are also
formed by a separation of the two laminae of the dura mater,
though their shape is so different from that  of the others.
They are situated at the  sides  of  the sella turcica, and  on
the body of the sphenoid bone.  Their cavity is very irre-
gular, and is furnished with a number of filaments,  which
cross in every direction, and give it a cellular arrangement.
The  internal carotid artery and the sixth nerve traverse it,
but are protected by its lining membrane  being  reflected
over them.
   The cavernous sinus anastomoses in front with the circu-
lar sinus, and behind with the two petrous sinuses and the
anterior  occipital.  It receives, in  front, the ophthalmic
veins; from  above, the anterior and inferior cerebral veins;
and on the sides, some veins from  the dura mater.

   7.  The Sinus Circularis is placed in the sella turcica, and
surrounds the  pituitary gland.  It is a small cavity  which
receives  the veins of this gland,  and, as just mentioned,
communicates with the cavernous  sinus.

   8.  In the posterior part of the base of the cranium, there
 are also some other sinuses called, from their position, Oc-
 cipital.   One of these is upon  the basilar process of the os 
342
NERVOUS SYSTEM.
 occipitis, and extends itself directly across the bone, from
 the hind part of one cavernous sinus to the corresponding
 point of the other; and is, therefore, a means of communi-
 cation between these two cavities.  Another of these sinuses
 extends from the region  of the torcular  hierophili, or the
 upper extremity of a lateral  sinus, along the base of the
 falx cerebelli to the posterior margin  of the  occipital fora-
 men, where it bifurcates  and then goes along  the margin of
 this foramen to  discharge itself into the lateral sinus at the
 posterior foramen lacerum.

   The smaller sinuses about the base of the cranium, besides
 the outlets  mentioned, have collateral ones,  which  pass at
 different places  through  the base of the cranium, and run
 into the branches of the internal jugular vein.  These com-
 munications were  known to Santorini, and are called his
 Emissaries.


              Of the Tunica Arachnoidea.

   This membrane  is the second of the envelopes  of the
 brain, and  is spread over the surface of the pia mater, ad-
 hering to it closely in the greater part of  its extent.   It is
 so diaphanous and thin, as its name implies, that it is distin-
 guished with some difficulty, wherever it adheres to the pia
 mater; which it does all  over, with the exception of some
 few places  on the basis of the brain, as, for example, just
 in front of  the tuber annulare, and  behind the medulla ob-
 longata. There this membrane may be seen stretched from
 one prominence to another, and separated considerably from
the pia mater. It does not follow the anfractuosities  of the
brain, but goes directly across them, from the ridge  of one
convolution  to that of the adjacent, so that it is  entirely
smooth  and uniform in its distribution.  Notwithstanding
the general closeness of its connexion  with the pia mater,
it may yet be separated from  it by careful dissection, by
slight maceration, or by the use of the blow-pipe; dropsical
effusions frequently make out the distinction between the
two membranes; also the deposite of coagulating lymph. 
MEMBRANES OF THE ENCEPHALON.
J43
  Considering this membrane as a single layer, we have to
speak of the dura mater as lying loosely upon it.  But the
authority of Bichat, sanctioned  by the testimony of many
other anatomists, has assigned to it a much more considera-
ble extent.  For it  seems to be well ascertained, both by
analogy and by  observation, that it is a sac; which, besides
covering the external surface of the pia mater, is reflected
over the internal surface of the dura mater, and gives to the
latter its smooth shining appearance.   This lining is on the
same principle  that the serous lamina of the pericardium
lines its fibrous  lamina, or that the synovial membrane lines
the ligamentous attachments of an articulation.  In the early
periods of life,  it may be separated from the dura mater by
dissection.  Vicq. D'Azyr has related a case in which it was
 detached  by a collection of pus.   Its places of reflection to
 the dura mater  are  on  the basis of the cranium, where the
 blood vessels and nerves pass into the sheaths formed by
 the dura  mater, and along the blood vessels entering into
 the sinuses.
    The tunica arachnoidea passes into the ventricles of the
 brain by  the same apertures that  the pia mater does, but it
 is much less manifest there than  elsewhere.
    The texture of this membrane is exceedingly delicate and
 fine.  It is always  found, in health, in a transparent state,
 and is furnished with neither red blood vessels nor nerves.
 It secretes a sort of halitus, or  synovia, which facilitates
 the motions  of the brain, and  prevents it from adhering.
 Occasionally, this secretion is so much augmented as to con-
 stitute a genuine dropsy.

                    Of the Pia Mater.

    The Pia Mater,  or Tunica Cerebri Vasculosa, is in con-
 tact with  the substance of the brain.   It also is  extremely
 delicate,  but, unlike the  last, is furnished with an immense
 number of blood vessels  which go to or return from  the
 brain, and are,  in most subjects, so abundant that they give
 a florid appearance, at a  little distance, to the whole mem-
 brane.  Its external face appears  entirely smooth, owing to 
J 44
NERVOUS SYSTEM.
its being covered, and its processes  cemented  together by
the tunica arachnoidea; but its internal face  exhibits these
processes as following precisely the anfractuosities of the
brain; consequently it is very unequal.
  The pia mater presents, along the course of the longitudi-
nal sinus, an abundance of those small graniform bodies,
existing also in this sinus, and called Glandulae Pacchioni.
They  beset the veins as they enter into  the  longitudinal
sinus,  and  even follow them there,  so that there is a chain
of them  from the surface of the pia mater into the sinus.
They are frequently so abundant on the superior part of the
hemispheres, near the great fissure, that they cause the dura
and pia mater to adhere, as if from inflammation.  It is the
larger of this kind which frequently produce an absorption
of the dura mater, and of the internal  table of the  skull.
These bodies are also found,  along  with the pia mater, in
the ventricles of the brain, as at the  external margin of the
plexus choroides, around  the  pineal gland, and at the bot-
tom of the  fourth ventricle.
  The Glandulae Pacchioni, wherever  found, present a si-
milar appearance and structure; varying much in size, they
are generally in clusters, which repose on common bases.
Anatomists differ  much in their opinion concerning them.
Bichat acknowledges his complete ignorance on the subject;
Portal says that they are only congeries of vessels or of cel-
lular bodies filled with fat.  Meckel states, that as they are
found  especially in the latter periods of  life, and never be-
fore birth;  as they never  exist in  very great abundance,
except in persons who have often experienced diseases of
the head; and are not observed  in any animal: that we are
forced to consider them as morbific productions, and not as
Pacchioni conceived, glands whose excretory ducts opened
into the ventricles of the brain.

  The Pia Mater covers the upper surface of the cerebrum
with such  uniformity as not to require a detailed descrip-
tion of it; where it sinks into  the great fissure of the hemi-
spheres;  it adheres from the two sides just above the corpus 
MEMBRANES OF THE ENCEPHALON.
345
callosum.   On the basis of the brain, it penetrates deeply
into the anterior fissure or the Fissura  Sylvii; is reflected
over the inequalities, but never in such a way as to leave
them; and closes up the bottom of the third and of the fourth
ventricle.
   The distribution of  the pia mater, over the ventricles of
the brain, is more  complicated than that over its periphery,
and it may be remarked, that this  portion is called, by some
anatomists, the Internal Pia Mater; that its texture is much
more delicate, and net-like, and that it adheres more closely
to the subjacent parts.  Being extended from the superior
surface of  the cerebellum and of  the tuber annulare,  it en-
ters into the third ventricle, under the  posterior  margin  of
the fornix, by the large transverse fissure between the latter
and the tubercula quadrigemina.  By its course between the
fornix and thalami, it constitutes the Velum Interpositum,
or the Tela Choroidea of Vicq. D'Azyr.   The pia mater is
also introduced  into the inferior cornu  of the lateral ventri-
 cles along the internal margin of the hippocampus major, at
 the side of the  pons varolii; and  into  the fourth ventricle
 from its bottom part.

    The several plexuses of vessels found in the ventricles of
 the brain have for their basis the pia mater; which is arranged
 into a great  number of folds, some of them being longitudi-
 nal and others crossed.  Their formation, according to the
 new views which have been taken of the development and
 growth of the  brain, by Tiedemnnn,  depends upon the  in-
 ternal membrane  of the brain contracting itself as it finishes
 the deposite of medullary mattercalled Centrum Ovale. The
 vessels of the plexuses are the arteries, which are spent upon
 the surface of the ventricles, and  the veins derived from the
 same; the latter are much more numerous than the first.

    Of the  Structure of the  Pia Mater.—The pia mater is
 commonly spoken of as a complete membrane, yet its struc-
 ture is different  from that of membranes generally, inasmuch
 as it is a net-work,  the meshes of which are formed  by  ar-
 teries and veins,  and the interstices  filled up by a  loose,
    Vol. II.—44 
31G
NERVOUS SYSTEM.
weak, cellular substance.  Bichat has very justly observed,
that the union with the tunica arachnoidea is solely on the
part of this cellular substance; whereas the union with the
cerebrum is  confined to the vessels, which  are extremely
numerous and very small before they penetrate it, and ap-
pear as bloody points when we cut into the substance of the
brain.  The principal arterial trunks of the pia mater are at
the basis  of  the brain;  these trunks divide into smaller
branches, in  the anfractuosities and  fissures.  The primary
divisions again  divide  and subdivide  into tubes not much
exceeding the size of capillary vessels.   In this last state
they enter the brain, and may be seen very readily, either
by a fine injection or by tearing up the pia mater.

        SECT. II.—OF THE MEDULLA OBLONGATA.

  According to the usage of the best authorities of the pre-
sent day,  who follow in the description of the central parts
of the nervous system, the order of their development in the
human subject,  and also of their appearance in  animals; I
shall describe the encephalori from below upwards instead
of from above downwards.  The preference thus shown is,
perhaps,  principally serviceable in  fixing upon  the mind
the order of growth and appearance, which according to
well established  experiments are exactly in the order of
importance to life.

  The Medulla Oblongata, also  called Bulbus Rachidicus,
extends from the superior margin of the first cervical ver-
tebra to the middle of the basilar  process of the os occipi-
tis.  It becomes gradually larger as it ascends, and is about
an inch in length, and eight lines wide at its base.   It is
by no means  so cylindroid as the medulla spinalis, but pre-
sents several  risings and depressions on its surface.
  The under surface of the  Medulla  Oblongata is divided
longitudinally by the middle fissure, a continuation of that
on the front of  the Medulla Spinalis.  The  fissure  is two
or three lines deep, which is rendered manifest by removing
the pia mater.  On either side of it is an oblong body called 
THE MEDULLA OBLONGATA.
347
Corpus Pyramidale, which is* a continuation of the chords
that decussate from the opposite sides of the spinal marrow.
These bodies occupy the whole length of the Medulla Ob-
longata, increase in breadth as well  as in elevation during
their ascent, and are, lastly, somewhat constricted or dimi-
nished abruptly, where they join the Protuberantia Annu-
laris or Cerebralis.   Precisely at the latter point, between
their bases, is a deep triangular  pit, into which penetrates
the pia mater.   J. F. Meckel says, that they are united at
their lower  extremities  by  a small transverse medullary
Commissure, of a line and a half in breadth.  This junction
is above the decussation of the chords from which the Cor-
pora Pyramidalia arise.

   The Eminentiae Olivares are  two bodies;  one  on either
side, at the external margin of the pyramidale.  They are
about seven lines long;  two  and a half wide, and are ele-
vated to the height of one line.  The elevation ceases some-
what short of the annular protuberance,  but  their interior
structure is  continued  into the  latter, and may be traced
into the thalamus nervi optici.
   Like the pyramidalia,  those bodies are medullary exter-
nally;  but within there  is a  nucleus of cineritious matter
called, from the irregularities of its margin,  Corpus Fim-
briatum, and which encloses some medullary  matter.  The
corpus fimbriatum is  open at the inner circumference, and
has the medullary matter which it contains~continuous there
with the substance of the corpus pyramidale.  Below,  its
circumference  is continuous with the cineritious matter of
the  medulla spinalis.   In the slight depressions  between
the corpora pyramidalia and the olivaria, are the roots of the
hypoglossal nerves.

  The Corpora Restiformia,  one on either side, are placed
at the lateral posterior margins of the  medulla oblongata,
just posterior to the olivaria; and are  readily brought into
view by elevating the contiguous part of the cerebellum.
They are elliptical risings of an inch in length; their lower 
34«                NERVOUS SYSTEM.
extremities are in contact, and project where they begin to
arise  from the borders of the  posterior fissure of the me-
dulla oblongata; they then diverge, and advance forwards
and upwards to terminate above in the cerebellum.
   The  corpus restiforme is  formed  of medullary matter,
and is a continuation of the posterior cord of the medulla
spinalis.  From  its superior posterior  margin a thin me-
dullary lamina of about three lines square arises, and  being
sustained by the pia mater, advances to  meet its fellow,  but
does not absolutely touch it. *   From the anterior margin
of each corpus restiforme there departs  a second process of
medullary matter, larger and more thick than the preceding,
and  being covered by the roots of the pneumogastric and
glosso-pharyngeal nerves,  adheres to the plexus Choroides
of the fourth ventricle.

   The superior face of the medulla oblongata is excavated
between the corpora restiformia, in  such a way as to present
the outline of a writing pen, and is  therefore called  Cala-
mus Scriptorius; which  forms a considerable  part of the
floor  of the  fourth ventricle of the  Brain, or the  sinus
rhomboideus.  The fissure, in its middle, corresponds with
the slit  of a pen, the nib being downwards; and the fissure
extends from the posterior fissure of the medulla spinalis
the whole length of the medulla oblongata.
   The calamus scriptorius  is marked by several streaks of
medullary matter,  which extend themselves transversely
with a very slight degree of obliquity upwards, and reach
the external margin of the corpus restiforme of the corres-
ponding side.  These medullary  striae present some varie-
ties in regard to their volume, number,  and  arrangement.
Sometimes they are slightly elevated narrow lines,, which
are perfectly distinct from each  other, and from  one to
fourteen in number.  On other  occasions their volume is
greater, but they  are not so numerous.  They generally ex-
tend,  either one or all, from the middle fissure  to the  com-
mencement of the auditory nerve,  and  are  thereby a part
* Called Pons Sinus Rhomboidei by J. F. Meckel. 
THE MEDULLA OBLONGATA.
349
of its origin.  Sometimes the anterior ones are directed to-
wards the origin of the trigeminus nerve, but their union
with it is not yet ascertained; the posterior ones are some-
times blended with the radical filaments of the pneumogas-
tric nerve.  The striae themselves, are sometimes interwo-
ven or blended, and pass the boundary of the middle fissure
to join with those of  the other  side.   Their  roots may be
traced occasionally along the  middle fissure,  almost to the
front or  under surface of the  medulla oblongata.   Meckel,
whose observations on this subject are  highly interesting,
is disposed to consider the striae  not only as forming the
roots of  the auditory nerve, but as also related closely to
the trigeminus and to the pneumogastric.
   On  this  surface also  of the fourth ventricle, or 'sinus
rhomboideus, but in  advance  of the  preceding striae, there
is another on each side still  larger, which may be distin-
guished  by its always beginning at some distance from the
middle fissure.  Its direction is transverse,  and it passes
just above the anterior extremity of  the corpus restiforme,
to run into, or to assist in forming, the root of the auditory
nerve.   Its existence is much  more constant than that of
the others.   It is considered  as an assistant ganglion to the
auditory nerve, and in cases of deafness has been deficient.
Being principally cineritious, it is  called Fasciola Cinerea.
   In tracing  the  continuation of the structure of the me-
dulla spinalis,  into that of the  medulla oblongata, we find
that  each of the anterior cords of  the medulla spinalis di-
vides into an anterior, and into  a  posterior fasciculus; the
first is the smaller, crosses the  middle  fissure, at the decussa-
tion of Mistichelli, and continuing its course upwards, forms
the corpus pyramidale; while  the larger ascends behind the
eminentia olivaris, and forms the  floor of the sinus rhom-
boideus.   There is a  third fasciculus of white matter be-
tween  the other two,  into which the  anterior column of the
medulla  spinalis is divided.   It is described by Rosenthal,
who  says, that it touches the eminentia  olivaris,  surrounds
it, and after having traversed  the annular protuberance, ter-
minates in  the tubercula quadrigemina. 
350
NERVOUS SYSTEM.
  The posterior cords of the spinal  marrow, being  conti-
nued  into the corpora restiformia, become still more evi-
dently divided into two fasciculi, from an increase of their
volume,  than they were  in the vertebral canal.   The
internal of these fasciculi  stops by  a pointed  termination
near  the borders of the sinus rhomboideus; while the ex-
ternal is continued on towards the cerebellum;  through the
annular protuberance.
         SECT III.--PROTUBERANTIA ANNULARIS.

  The Annular Protuberance (Protuberantia Annularis,
Nodus  Cerebri,  Pons  Varolii)  is  the  large  projecting
body, placed near the centre of the base of the encephalon,
at the top of the Medulla Oblongata, and upon the junction
of the body of the  sphenoid bone with the basilar process
of the os occipitis.  It is convex, and about an inch in di-
ameter, its  transverse measurement being  a  line or two
larger than the other.   It is divided by a superficial fossa
into two symmetrical  halves, right and left.
  When the pia mater is removed from the Protuberantia
Annularis, the under  surface  of the  latter is seen  to  be
formed by transverse  medullary fibres which come from
the crura  cerebelli.   When these,  which  are commonly
one or two lines in depth, are  removed by scraping or cut-
ting, a cineritious matter is exposed,  which is traversed by
numerous  layers of medullary matter also going in a trans-
verse direction.   About two lines deep from the surface of
the protuberance,  near the middle of each of its halves,
are found  some  longitudinal  medullary fibres  connected
with cineritious matter, and which may be fairly traced as
a continuation of the  fibrous  structure of  the  pyramids.
These fasciculi passing on  through  the protuberance, are
continued so as to  form  the under surface of the crura of
the cerebrum.
  Lying still deeper than the  medullary fibres alluded to,
there is an accumulation of cineritious matter, intermixed 
                   THE CEREBELLUM.                351

with perpendicular medullary layers situated  one behind
the other.   Behind (or above when we stand erect) this in-
tertexture, a small fasciculus of medullary matter exists,
which  is a  continuation of the posterior fasciculus of the'
anterior  medullary cord, of  the medulla  oblongata, and
may be traced afterwards to the superior face of the crus ce-
rebri.


            SECT. IV.—OF THE CEREBELLUM.

   The Cerebellum, being placed in the posterior fossae of
the cranium, is separated by the tentorium from the poste-
rior lobes of the  cerebrum, beneath which it  lies.   It is
continuous  with the  Pons Varolii by a trunk of medullary
matter on each side  proceeding backwards and called the
crus of the cerebellum, which  is a root of the medullary
matter entering into  the composition of  the latter.
   It is of a rounded  form,  and well  fitted to the cavity in
which it reposes.   It is convex above and below; measures
about four inches  in its transverse diameter, two and a half
in thickness, and  about the same from  before  backwards.
The upper surface is divided into two equal parts or halves,
by a middle ridge, while the lower surface is divided in the
same way by a fossa.   These halves are called hemispheres;
their surface  is marked by many horizontal  fissures, the
edges  of which are  kept closed by the adhesion of the pia
mater.
   The fissures are interposed between  the laminae or con-
volutions of the cerebellum, which for the most part are
concentric, so  that the larger are behind,  while the  short-
est are in front, near the annular protuberance.  The pia
mater  penetrates  to  the bottom of these fissures, some of
which, when exposed fully by its removal, are found to ex-
tend to the depth of an inch or more. One of these fissures,
which exists  on the  superior surface  of the  cerebellum,
half an inch distant from the posterior and external margin
of the latter;  has  a circular course, and  is so well marked
by its  size and depth that it is called the Sulcus Superior 
352
NERVOUS SYSTEM.
Cerebelli.   Another, situated under similar circumstances
on the inferior surface of the  cerebellum, is called the Sul-
cus Inferior Cerebelli.   On the latter surface, also, there
are two or three more of a middle size, situated between
the sulcus inferior and the  tuber annulare.   These larger
sulci have given occasion to anatomists to multiply most un-
reasonably the number  of lobes of which  the  cerebellum
consists. Bichat's mode of description is preferable: he says,
that by cutting (vertically) through one of the hemispheres
of the cerebellum, so  as  to expose the thickest part of its
medullary matter, that six or seven principal fissures  will be
seen,  which, by penetrating to a considerable depth, divide
the cineritious portion into  as many concentric parts.  In
the interior of these fissures there are much smaller ones,
which pass at right angles to them.   On the surface or pe-
riphery of the  cerebellum,  in the intervals of the larger
fissures, there are many  small ones, which though general-
ly horizontal, terminate in each other by acute angles.  The
superior middle ridge of the cerebellum from its shape and
position is  called by Vicq. D'Azyr, Vermis Superior; the
anterior extremity of which, from its elevation, is the Mon-
ticulus Cerebelli.

  The  Valve of Vieussens (called  also velum  medullare,
valvula cerebri) arises from the cerebellum, just under the
anterior part of the  base of the monticulus, and runs ob-
liquely upwards to terminate  in  the testes.   Sometimes it
is marked, in  its middle, by a longitudinal line or slight
fissure, from either side of which proceed small lateral ones.
It is principally medullary, and has a small quantity of cine-
ritious matter at  its extremities.   It is thinner in the mid-
dle than at either of its margins.

  The middle inferior part of the cerebellum,  which pre-
sents  the deep sulcus  running  longitudinally and forming
the division into hemispheres, has a long ridge occupying
the sulcus.   This ridge  is the Vermis Inferior  of Vicq.
D'Azyr, and is so concealed by the adjacent portions of the 
THE CEREBELLUM.
353
hemispheres, that a good view of it can be got only by re-
moving the pia  mater and pushing the  hemispheres aside.
The transverse fissures which penetrate it, and its general
irregularity of surface, will then be sufficiently distinct.
The pia mater passes from the fore part of this body to the
medulla oblongata,  and thus assists in forming the floor to
the fourth ventricle;  which, without  this reflection, would
be exposed.   The  central part  of the cerebellum, formed
by the vermis superior and  by the vermis inferior, is the
Fundamental Portion of Gall and Spurzheim.
   The substance of the cerebellum is formed of cineritious
matter externally, and of medullary matter internally. When
a vertical section of it is made through the middle of one of its
hemispheres, the medullary matter puts on the appearance of
the thuya or arbor vitae, the roots and ramifications of whose
limbs, even to their smallest extremities, are surrounded by
cineritious matter.  In this view, there appears to be more ci-
neritious than white matter; but when a horizontal cut is made
from the periphery to the  centre, parallel with one of the
deep concentric fissures, the proportion of medullary matter
seems to  be much  more  considerable; and the arbor  vitae
arrangement is proved to depend upon the laminae of me-
dullary matter radiating from the centre, or, in other words,
from the  massive  medullary trunk  in the interior of the
hemisphere of the cerebellum.   Each of these  radiations
commences by a root of considerable size, which  divides
and subdivides into  branches.    Each primitive  radiation,
as well as its branches, is covered by its own layer of cine-
ritious matter about one line in thickness, and is kept per-
fectly distinct from the contiguous ones by the fissures which
extend internally from the periphery of the cerebellum.
   In the middle of the trunk of the arbor vitae, exists the
Corpus Rhom boideum, or Dentatum. It is an oblong rounded
body, and jagged and cineritious in its circumference, but
medullary within.   Its configuration resembles that of the
corresponding body in the corpus olivare, with the addition
of its being larger,  and having its outline better marked. It
is the ganglion of the cerebellum of Gall and Spurzheim.
   Vol.  II.—45 
354
NERVOUS SYSTEM.
  The Central or Fundamental Portion of  the Cerebellum
exhibits also very clearly the arborescent arrangement, and
is furnished with about seven primitive radiations, coming
from  a medullary trunk.    The  proportion  of  medullary
matter to cortical,  is less in it than  in the hemispheres of
the cerebellum.  Each of the primitive radiations may be
traced to some  particular point or prominence  on the sur-
face of the fundamental portion, thus forming its basis; but
this study is more curious than useful, though several ana-
tomists have pursued it.
  The medullary mass of the cerebellum has, on each  side,
three fasciculi:  one of these  comes from the corpus resti-
forme of the medulla oblongata; a second ascends as the
valvula cerebri to join the testes; and  the third, called the
Crus  Cerebelli, runs to join the annular protuberance.   The
two first faseiculi belong to the middle or fundamental por-
tion of the cerebellum; they are consequently situated  more
internally, and are partially concealed  by the crus cerebel-
li, and have interposed between  them  and the  latter, the
Corpus Rhomboideum, or Dentatum,


             SECT. V.--OF THE CEREBRUM.

   The Cerebrum weighs about three pounds, and is seven
times as  heavy as the cerebellum.  It is ovoidal, and mea-
sures about six inches in its antero-posterior  diameter, five
inches in its greatest breadth, which is behind,  and four or
five in depth.   It is separated above by a deep fissure, (Fis-
sura  Longitudinalis,) into  two equal  parts called Hemis-
pheres. At the bottom of this fissure, by separating the con-
tiguous surfaces of it, is to be seen a broad lamina of me-
dullary matter passing from side to side and called the Cor-
pus Callosum, which  connects the two hemispheres  toge-
ther.   The under surface of each hemisphere is  subdivided
into three lobes; Anterior, Middle, and Posterior.
   The anterior lobes are placed upon  the anterior fossae of
the base of the cranium;  the Middle, upon  the  middle
fossae of the same:  and the Posterior  Lobes  rest upon the 
THE CEREBRUM.
355
tentorium.   The two anterior lobes are completely sepa-
rated by the  Fissura  Longitudinalis, which  extends  be-
tween  them to the base of the  cranium; the same  is the
case with the posterior lobes; the middle lobes have inter-
posed between them the annular protuberance and the crura
cerebri.  When the pia mater is removed, the anterior lobe
is seen to be marked off  from the middle  lobe by a deep
sulcus, in the  under  surface of the cerebrum, correspond-
ing, in its position, with the posterior margin of the Lesser
Sphenoidal Wing.  The boundary between the middle and
the posterior lobe is,  by  no means, well defined on the basis
of the brain,  but it is agreed to consider as posterior lobe,
all that part of the hemisphere which rests upon the tento-
rium.
  The  periphery of  the cerebrum is formed into convolu-
tions (Gyri) which give it an unequal tortuous surface, re-
sembling the intestines of a small child.   These convolu-
tions are separated by fissures (Sulci) of depths varying from
an inch to two inches or more.   The convolutions proceed
in diversified  and  complicated  courses, which never  cor-
respond in different individuals, and seldom on the two he-
mispheres of  the same brain.   Though their summit is ge-
nerally convex, yet some of them have it depressed slightly,
which is considered a proof of each convolution being divi-
sible into two halves or layers, placed side by side.   Some
of the convolutions are short, others long; they present nu-
merous varieties in the manner of joining each other.  Owing
to the narrowness  of  the fissures between them, they are
closely packed together, so that the lateral surfaces of each
one  are suited to such as are contiguous; occasionally there
is a  departure from this rule.
  The surface of the convolution, by which we mean not
only the most exterior periphery of the cerebrum, but also
the surfaces formed by the fissures to their very bottom, is
covered by cineritious matter of about one line in thick-
ness.
  Within the periphery of the cerebrum, the mass of medul-
lary matter is very considerable, and is of an ovoidal shape. 
356
NERVOUS SYSTEM.
This ovoid is called the Centrum Ovale of Vieussens, and
is brouglit fairly  into view by  making a  horizontal cut
through the hemispheres, two inches below their summit.
   In  proceeding with the anatomy of the cerebrum  from
its base upwards the following is the order or succession of
parts  in its structure:  In advance of the pons varolii, and
springing from it, there are two divergent medullary trunks,
one on each side, which  run forwards, and are lost in the
medullary substance of the cerebrum.  These trunks are the
crura cerebri, upon the upper surface of which are two pro-
tuberances:  the  posterior is the thalamus nervi optici, and
the anterior is  the corpus  striatum.   Each crus  cerebri,
having  penetrated into the substance of its  respective he-
misphere, expands by a multiplication of the filaments com-
posing it, so as to constitute the principal bulk of the he-
misphere.   These filaments may indeed be traced  very sa-
tisfactorily in almost every direction towards the periphery
of the cerebrum, where they terminate in the convolutions,
their extremities being covered  by the cineritious matter
there.   The arrangement is best seen  by scraping with a
knife  along the base of the brain, especially when the latter
has been hardened in spirits of wine, and it is constituted by
what are called by M. M. Gall and Spurzheim  the diverging
fibres of the brain.
   The point is not indeed entirely settled that the diverging
filaments  end  in the  convolutions, or  do not rather after-
wards inflect or double  on themselves, and  pass  inwards
again  to the middle line of the brain, forming by their con-
vergence  the corpus callosum.   At all  events, the fact is
quite  demonstrable that as the under and lateral portions of
the hemisphere  consist in diverging filaments,  arising in
and from the crus cerebri, so the upper portion and  the cor-
pus callosum consist in filaments which arise in the adjoin-
ing convolutions, and collect towards the middle of the cor-
pus callosum, where they  adhere to the congeneric filaments
of the other side.
   The arrangement is in the most simple conception and
illustration of it what would be exemplified by folding a strip 
THE CEREBRUM.
357
of cloth  double on itself, so as to convert it into a loop;
the under part of the loop  would then represent the di-
verging fibres of  the cerebrum and the upper part the con-
verging fibres, or corpus callosum; it being at the same time
borne in mind that the continuation of the two  orders of
fibres into one another in the brain is  not so fully ascer-
tained as it would be represented by this model.
  Between  the two orders  of fibres there is a horizontal
cleft or interval.   This interval is the  lateral ventricle of
the hemisphere, which may be got into under the posterior
margin of the corpus callosum, from its being open  there;
or rather only closed by an adhesion  of the membranes,
which is easily lacerated.
   The preceding is intended as a mere outline upon which
to form the  base  of the descriptive anatomy of the cere-
brum.  The following, therefore, may be considered as the
detailed account.

  The Crura Cerebri are rounded below; about eight lines
long, and  increase in  their  transverse diameter as they
advance; their vertical diameter  is about ten lines.  They
mutually diverge, beginning from  their roots, and are se-
parated by a deep fissure, considered as a  continuation of
that on the front of the medulla oblongata.   This fissure is
the third ventricle of the brain.   Their surface is marked
by superficial furrows, running longitudinally; and about
two  lines before the tuber annulare, by a transverse fasci-
culus of medullary matter, very slightly elevated; the optic
nerves also cross them obliquely  at their fore part.
  In regard to texture, the crus cerebri presents,  on its un-
der surface, a medullary layer of two lines in thickness; to
this succeeds a parcel of cineritious matter, which, on being
removed, is followed by a mixture of both  cineritious and
white matter, more abundant than either of the preceding.

  The Eminentiae Mammillares, or Corpora Albicantia, are
two  small bodies, one on each side, about the  size of a
French pea.   They are situated near the anterior extremi-
ties of the crura cerebri,  on their internal faces, and almost 
358
NERVOUS SYSTEM.
in contact with  each other.   Their  texture is medullary
without, and cortical within.

  The Infundibulum is placed immediately before the emi-
nentiae mammillares.  It is a flattened conoidal body half
an inch  long, with  its base  upwards, and its apex going
downwards and  forwards.   It is formed of cineritious mat-
ter.   Most generally its base is  hollow,  and opens into  the
third ventricle, but its point is closed.  J. F. Meckel, how-
ever, asserts  that  a  communication exists entirely through
it, from the pituitary gland to the third  ventricle, and that
he has frequently  proved it by  passing air or liquids from
this  gland, though the  experiment does not succeed when
he attempts the  injection from the third ventricle.

  The Pituitary Gland (Glandula Pituitarid) is situated
in the Sella Turcica, and is covered  so  completely  by  the
dura mater,  that only a small aperture is left  for the point
of the infundibulum  to pass through and to adhere to it.   It
is an ovoidal  body, the  greatest  diameter of which is trans-
verse, and amounts to six lines.   It is partially  divided, so
as to give the appearance of two lobes, of which  the ante-
rior is much  the larger.   It  is hard and cineritious,  with a
small quantity of medullary  matter within.  In either side
of it  there is a depression from which leads a small canal
towards the place where the infundibulum joins it; the two
canals are in  the latter place united into one.  In some very
rare  cases gritty matter has been found in it, as  there is in
the pineal gland.  It is also surrounded by pia mater.

  The Tuber Cinereum  or Pons Tarini, is a portion of the
under surface of the  crus cerebri, at  the floor of  the third
ventricle. It is continuous in front with the anterior mar-
gin of the corpus  callosum.  In front of the infundibulum
the optic nerves unite, after having  crossed obliquely  the
crura cerebri  from without inwards and  forwards.  In this
passage, where they reach the  middle of the crura, and at
the internal border of the same, they come in contact with
the tuber cinereum, from which they get a few filaments,
but of this more hereafter. 
THE CEREBRUM.
359
   The Thalami Optici, called, by Gall, the Posterior Gan-
glions of the brain (Ganglia Postica) are amongst the most
conspicuous parts of the internal structure of the cerebrum,
and are two in number, one for either side.  They are si-
tuated  on the superior  face of the crura cerebri, are  about
an inch and a half long  from behind forwards; and  about
eight or ten lines broad and deep*
   The Thalami are  convex  above and internally.  At the
junction of these two surfaces is observed a medullary line,
described under the  name of peduncle of the pineal gland.
Their  posterior extremity is likewise convex, and is divided
into three rounded prominences; one is above the other two,
and is the  Tuber culum Posterius Superius; the second  is
below  and  within (Corpus Geniculatum Internum)  and
the third is below and external (Corpus Geniculatum  Ex-
ternum.)  There is a fourth tubercle Tuberculum  Ante-
rius) which is situated on the upper convex surface  of the
thalamus;  it is produced by the fan-like termination  of a
large medullary fasciculus which comes from the eminentia
mammillaris.
   The thalami are somewhat flattened on the middle of their
convex internal surface, and  adhere there to each other by
a layer of cineritious  substance called Commissura Mollis.
When the  brain is  very slightly advanced in putrefaction,
or has been made soft by dropsy, this junction scarcely
seems to exist at all.
   The thalami are  medullary on the surface presented  to
the ventricles of the brain, but within they are a mixture of
cineritious with medullary matter.  The fibres of the me-
dullary are very intimately blended with the crura cerebri,
and radiate from within towards the circumference  of the
brain; some of them are placed in layers, and are connected
with the tubercula quadrigemina.

   The Corpora Striata,  or the Ganglia Cerebri Antica,  also
two in number, one for each side or hemisphere of the brain,
are situated before the thalami optici, at the bottom  of the
 lateral ventricles.  They are  about  two and a half  inches
 long,  convex  on their upper surface, and eight lines broad 
360
NERVOUS SYSTEM.
 broad at their front part, but taper very gradually to a point
 behind.   They are about  four lines apart in front, and are
 separated there by the septum lucidum, but their posterior
 extremities diverge from  each other, so as to admit the
 thalami optici between them.
   The surface of the  corpus  striatum is cineritious, but
 within it consists of cineritious and of medullary matter,
 placed in layers which alternate with each other.   These
 layers are arranged in a crescentic manner, so as to present
 the convexity upwards and the concavity downwards. The
 medullary substance is a  continuation of that of the crus
 cerebri and of the optic thalamus.  It enters at the posterior
 inferior part of the corpus striatum, and immediately divides
 into three layers, placed one above the other, and of which
 the two inferior are more narrow and short than the supe-
 rior.   The upper layer, in its progress forwards, is inter-
 rupted by a body of cineritious substance, which occasions
 it to divide into a multitude of distinct radiated fibres. The
 same circumstance attends  the  other layers, but in a more
 limited degree.  The medullary matter of the corpus stria-
 tum may then  be traced, in all directions, into the hemi-
 spheres of the brain.   The cineritious  substance of the cor-
 pus striatum is abundant, and is divided by some anatomists
 into two kinds, one of a light gray, and another  of a darker
 colour. The first forms the middle and inferior part of the
 corpus striatum;  the  second is  in greater quantity,  and is
 found principally above and between the two  upper lay-
 ers.  Such is the general plan of the structure of the  corpus
 striatum;  but, it should also be understood, that a close in-
 tertexture exists between  its  medullary and  cineritious
matter.
  The most satisfactory way of unravelling the structure of
the corpus striatum, is to scrape away  its  under surface, in
tracing its medullary matter from the crus of the brain, and
through the optic thalamus.  It will  then be seen, that the
medullary substance of  the  crus reaches the posterior infe-
 rior part of the corpus striatum, a:;d is immediately invested
 in the greater part of its circumference with cineritious mat- 
THE CEREBRUM.
361
ter, it then begins to expand after the manner of a fan into
filaments.   These filaments or fasciculi penetrate the cine-
ritious matter in various  directions, besides those just de-
tailed.  A particular exposition of them is given by Gall and
Spurzheim, in their anatomy of .the brain.

  The Taenia Striata is placed in the angle formed between
the internal margin of the Corpus Striatum, and the external
one of the Thalamus Opticus, where these two  bodies are in
contact and continuous with one another.  It is a small me-
dullary band,  not a line in breadth, commencing near the
anterior crura of the fornix, with which it is connected fre-
quently by filaments, and observing the curved course of
the fissure in which it is placed, it goes to the  posterior end
of the  corpus  striatum, and even beyond it in most cases,
by uniting itself to the  top of the Cornu Ammonis.

   The Corpus Callosum.  When  the fissure between the
hemispheres of the cerebrum is widely separated, or when
the superior part of the hemisphere is  cut away on a level
with the bottom of the fissure, the Corpus Callosum, a me-
dullary layer, is brought fully into view.  This body unites
the medullary mass of  the  two hemispheres,  and is a large
 commissure.   It occupies about two-fifths of  the long dia-
 meter of the  brain, being nearer to its anterior  than  to its
posterior  end,  and is  about eight  lines  broad,  increasing
 however somewhat in breadth posteriorly.  The lateral half
of it,  on either side, is concealed by the hemisphere over-
lapping it, but  is prevented from adhering by a horizontal
fissure which  extends from one end to the otaer. It has an
arched form,  being convex above and  concave below.  Its
 thickness  is uniformly about three lines, with  the exception
of its anterior and  its posterior margins, which are  more.
   The middle line of its upper surface is marked out from
 one end to the other by a very slight depression, the Raphe;
on each side of which there is a very small linear elevation
 of the same extent, but slightly curved  inwards towards its
 fellow.  From these longitudinal lines there proceed out-
 wardly transverse  ones, having a fibrous appearance.  At
   Vol. II.—46 
'364                 NERVOUS SYSTEM.

the anterior and posterior ends of the corpus callosum, the
latter are somewhat curved  and radiate towards the peri-
phery of the brain.   Other longitudinal lines also exist on
this surface of  the corpus callosum, but they are not seen
with equal facility.   The anterior extremity of the corpus
callosum is rounded  off, and bent downwards towards the
basis of the brain, in such manner as to present backwards
its concavity; which thus embraces the fore part of the cor-
pora striata, and closes the lateral ventricles at this point.
The posterior end of the corpus callosum is rounded, also,
and continuous with the fornix and with the cornu ammonis.
  By examining the Corpus Callosum  from below, or  by
looking at  its relative situation and shape on a hemisphere
which is accurately separated  from its fellow in the middle
line, it will be  seen  that its lower surface is very  concave,
being highly arched from before backwards; that it forms
the roof of the  lateral ventricles, and  that this surface of it
is about two inches in its transverse diameter, and therefore
more than  twice as broad as the upper surface.

  The Fornix (Trigone Cerebral, of the French)  is placed
immediately below the  corpus callosum.  It  is a triangular
body of medullary matter, the base of which is behind and
the apex in front.   It is  about an inch and  a half long in
its  body, and  one  inch wide at its  base.  It is the latter
part which, lying immediately beneath the posterior end of
the corpus callosum, is continuous with it, and causes the
fornix to be considered  as a part of the same structure with
the corpus callosum.   These two bodies, which may be
compared to a sheet of  medullary matter doubled on itself,
have  their surfaces in  contact for a short distance behind,
the fornix  afterwards, by advancing and  keeping itself  in
close contact with the thalami nervorum opticorum, which
are just below it, diverges more  and more from the under
surface of  the  corpus callosum.  It  conceals all the upper
surface of the thalami except their external  margin, and,
having reached their anterior  extremity, its apex  descends
towards the basis of  the brain. 
THE CEREBRUM.
363
  The body of the fornix is about a line thick, but, at its
anterior extremity, it becomes  somewhat  cylindrical, and
is divided into two columns, called Crura Fornicis Anterio-
ra.   Each of these crura, in descending adheres to the an-
terior extremity of the thalamus of that side, and, getting
finally below it into the floor of the third ventricle, it,  after
a course slightly curved, joins the cortical  substance of the
Eminentiae  Mammillares.   Santorini,  aware of this junc-
tion, considered the eminentiae as a part of the fornix, and
therefore called them Bulbi Fornicis.
   The fornix has  other attachments of a more complex de-
scription, which the anatomist should attend to, as  they
serve to indicate the modes of intercourse between  the se-
veral parts of the cerebrum.   Its fibres  having reached,
and probably formed, the eminentiae mammillares; one fas-
ciculus  of them ascends from there along the internal face
of the optic thalamus, invested  by the cineritious matter of
the latter, and spreads itself above like a fan, and forms the
tuberculum  anterius: a second fasciculus from  the  same
point, having divided into two after going a short distance,
sends one division backwards along the upper internal face
of the optic thalamus, to join the peduncle of the pineal
gland, and the other division, which is more anterior, runs
to join the taenia striata; a third fasciculus from the eminen-
 tia mammillaris,  being  covered by the optic nerve,  goes
outwards and backwards to terminate in the thalamus nervi
 optici.
   The posterior margin, or the base of the fornix,  besides
running into  the  corpus callosum,  has the  angle on each
side elongated so  as to rest upon and to join the upper end
of the cornu ammonis.   The angle, being continued, then
follows  the winding course of the latter, adhering to its
posterior margin, but hanging loosely over the anterior.
This loose edge or continuation of the external margin of
the fornix is the Taenia Hippocampi, or Corpus Fimbri-
atum.    The elongations of the posterior  angles are called
Crura Posteriora  Fornicis.   In  the  brains of individuals
who have suffered from general dropsy, one frequently finds
the fornix narrower  than usual, and in its middle a fissure
which separates almost completely its two halves. 
J64
NERVOUS SYSTEM.
   As the fornix is suited  to  the upper surface of the optic
thalamus, it is of course concave below and convex above,
or resembles a triangular arch resting upon its three points
or angles.   Owing to some misunderstanding of the origi-
nal Greek word +«a<s, which,  according to the interpre-
tation  of Sabatier,  means a vault,  and thereby expresses
the whole body,  anatomists with the exception  of him,
have generally supposed the striated under  surface of the
fornix to be meant by it, and have called this surface Lyra,
in which mistake one has  followed another.

   The Septum  Lucidum is a partition placed vertically in
the middle line of the brain, and extends from the corpus
callosum  above to the fornix below.  It is of a triangular
shape, but irregularly so,  being much broader before than
it is behind, and having its edges so  incurvated as to fit the
bodies against which it is  applied.
  The septum  lucidum is formed by two laminae placed
side to side, but not  adhering to each other, and  leaving
therefore an interval between them,  called the Ventriculus
Septi, or  the fifth ventricle.  Each  of these laminae con-
sists of two  layers; the internal is medullary substance, con-
tinuous with that of  the corpus callosum and of the fornix;
and the external is a layer of cineritious  substance.  The
cavity is about an inch and a half long by a line wide, and
is narrower  in the middle than at either extremity.  It is
lined  by  a delicate serous membrane, which becomes mani-
fest when the halitus that  naturally covers its surface is ac-
cumulated into a body of  water.   It is generally supposed
to  be insulated or completely shut up, yet occasionally it
has been  found elongated  in front,  towards  the space be-
tween the anterior commissure and the anterior crura for-
nicis,  and to communicate there with the third ventricle.*

  The Pineal Gland {Glandula Pinealis, Conarium)  is
placed beneath the posterior margin of the fornix, upon the
superior tubercula quadrigemina or the nates.   It is an ob-
long spheroidal body, the long diameter of which is trans-

                     * J. F. Meckel. 
1 HE CEREBRUM.
365
verse, and  amounts to three  or  four lines, while the short
diameter is about three lines.  The substance of the pineal
"•land is cineritious,  and of  a reddisli colour.   At  its  in-
ferior part therr.  is a small  cavity,  sometimes  lined with
medullary  matter, and the orifice of  which looks towards
the third ventricle.
   This body is  connected to the adjacent parts by  several
cords.  From its bottom there  proceeds, on each side, the
long medullary filament called  its  peduncle,  which runs
along the upper internal face of the thalamus opticus, and,
as observed, joins or is continuous with one of the filaments
from the Eminentiae Mammillares.   From its base there
 proceeds a transverse  lamina of medullary matter, called
 the Posterior Commissure of the brain, which first advances
 forwards, and then recedes, so as to be in some measure
 doubled on itself.   This  lamina, at either end,  is united
 to the  upper posterior part of the corresponding  optic tha-
 lamus, and by its lower margin runs into the superior edge
 of the tubercula quadrigemina.
    Within the pineal gland,  and  sometimes on its  surface,
 there is an accumulation of  calcareous matter,  the Acervu-
 lus Cerebri, that appears about the  sixth  year of life, and
 continues for ever afterwards.   It is variable both in quan-
 tity and in its mode of concretion, for sometimes there are
 only a few atoms of grit,  scarcely distinguishable by the
 feel; while on other occasions  it is collected  into a body of
 irregular  shape, and more  than  a line in diameter.  The
 pieces of  which the acervulus consists, are sometimes united
 by cellular substance, and enclosed in a sac.   Their chemi-
 cal analysis presents phosphate of lime in large proportion,
 carbonate of lime,  and animal  matter.
    A reflection of pia mater, the Velum Interpositum, sepa-
 rates the pineal gland from the fornix, and the fornix from
 the thalami nervorum opticorum.

    The Tubercula Quadrigemina (or the Nates et Testes)
  are situated on the superior face of the crura cerebri, and
  just behind the thalami nervorum  opticorum.    A very 
36G
NERVOUS SYSTEM.
complete view of them is obtained by separating the poste-
rior lobes of the cerebrum, and by paring off the vermis su-
perior cerebelli.   Though the name implies  four  distinct
prominences, yet they are formed from  a common  mass of
nine or ten lines square,  on the posterior surface of which
these prominences arise.   They are in pairs, and are sepa-
ted from one another by a crucial depression.   The largest
or upper pair is the Nates, the lower pair the Testes.  The
external surface of these bodies  is medullary, and within
they  are cineritious.  From  the  Nates there proceeds a
considerable medullary fasciculus, which runs  forwards to
join the Corpus Geniculatum Internum on the internal pos-
terior face of the thalamus nervi optici; there proceeds also
from them a second  fasciculus, which either joins the optic
nerve itself, or the  contiguous part of  its thalamus.   The
Testes receive, at their lower end, the valve of the brain;
and there also proceeds from them a large fasciculus of me-
dullary matter, which joins the corpus  geniculatum exter-
num of the optic thalamus.


             Of the  Ventricles of the Brain.

   These cavities are four in number, two called lateral arc
placed one in either  hemisphere of the cerebrum, a  third is
between the two thalami, and the fourth under the cere-
bellum.  They have all  been alluded to, but only  superfi-
cially.
   The Two Lateral  Ventricles ( Ventriculi Laterales) are
horizontal  cavities  or fissures of an extremely irregular
shape, in the very centre of the hemispheres, being the in-
terval between the diverging and converging filaments of the
cerebrum.  They are separated from each other only by the
septum lucidum; are covered  over by the corpus callosum,
and have the fornix, thalami optici, and corpora striata for
a floor.  Each  one consists in a  body or principal  cavity,
and three processes called cornua.  The body has been suf-
ficiently described in speaking of the parts which constitute
its parietes; but the processes  are yet to be considered. 
THE CEREBRUM.
367
  The Cornua, from their position, are named Anterior,
Posterior, and Lateral or Inferior.  The Anterior is a very
small space  between  the anterior extremity of the corpus
striatum and the opposite surface of the hemisphere, and has
nothing in it particularly deserving of notice.  The Poste-
rior Cornu extends from the base of the fornix to the dis-
tance of  an inch  or more in the  substance of the posterior
lobe of the cerebrum.   Its cavity is  conoidal, somewhat
curved, with its  convexity outwards, and  of six or seven
lines in diameter in its base.  Its internal side is furnished
with an  oblong  eminence called Hippocampus Minor, or
Ergot, from its  resemblance to a cock's spur, but its size
and form are somewhat variable.  When  this eminence is
cut through transversely, it  is easy to see  that it is formed
by a convolution of the posterior lobe projecting into the
posterior cornu.  The convolution is covered by medullary
matter on the side of the ventricle, and of course by cine-
ritious on the side of the periphery of the brain, and is the
bottom of an anfractuosity.

   The Inferior,  Middle, or  Lateral Cornu, of the Lateral
ventricle is situated in the middle lobe of the cerebrum.  It
 commences at the posterior angle of the fornix, and winds
 downwards and  forwards in a semicircle towards the fissure
 of Sylvius, presenting its convexity outwards, and its con-
 cavity within.   Its floor is furnished  in  its whole length
 with an  elevated ridge, the surface of which is semicylin-
 drical. This ridge is the Cornu Ammonis, or Hippocampus
Major, and increases somewhat,  both in breadth and eleva-
tion, as  it winds down the  process of the ventricle.   Its
lower or anterior extremity is terminated by two or three
small tubercles,  and is the Pes Hippocampi.  Occasionally
the hippocampus major is marked off by a middle longitu-
dinal fissure into two elevations, of which the external is
the smaller.  On  its concave side there  is a thin edge of
medullary matter, continuous with the external  margin of
the fornix.  The extremity of a knife handle may be insinu-
 ated for a short distance  between this edge and the hippo- 
66$
NERVOUS SYSTEM.
 campus; it ceases about halfway down the latter, and in the
 natural state of the parts  is concealed by the  plexus cho-
 roides.  This edge  is, as  mentioned in the account of the
 fornix, the Taenia Hippocampi or Corpus Fimbriatum. Be-
 neath the latter, and partially covered by it, there is another
 body,  which presents itself in the form of a small chord of
 cineritious matter, it is not quite so long as the Taenia, and
 is called Fascia Dentata, from being divided into several sec-
 tions by transverse fissures, which give it an undulating ap-
 pearance.
  A transverse incision of the Hippocampus Major shows
 that it is a body of cineritious  matter,  covered on its sur-
 face by a thin layer of medullary  substance.

  The Third Ventricle (Ventriculus Tertius.)  When the
 fornix is separated from its anterior crura and turned over
 backwards,  the process of pia  mater,  called Velum Inter-
 positum, is found  between it and the optic thalami.   This
 process is of a triangular shape, resembling the fornix, and
 is about the same size; it is insinuated into this place from
 the surface of the brain, under  the posterior margin  of the
 corpus callosum.   Its lateral margins, which project beyond
 the corresponding ones of the fornix, are formed by a con-
 geries  of convoluted vessels, constituting the plexus  cho-
 roides.   The plexus, indeed, may be traced  from the pes
 hippocampi  along  the  corpus fimbriatum to its position on
 the margin of the  velum interpositum; and insinuates itself
 from the bottom of the cerebrum  between the pons varolii
 and the  convolution forming the  hippocampus major; but
 when it reaches the anterior end of the fornix its convoluted
 character ceases, and it terminates, on each side, in a single
vein, (vena galeni,) which runs from before backwards, in a
 straight line, near the middle of the velum  interpositum.
The vein finally unites with its fellow to form a single trunk,
 which  runs into the fourth sinus of the dura mater.
  The Tela Choroidea or Velum Interpositum adheres very
 strongly to the  fornix, by means of small vessels; it may be
 raised with less difficulty from the thalami, though it serves 
THE CEREBRUM.
369
         10 keep the third ventricle closed above, with  the  excep-
         tion of the part just behind the crura of the fornix, where
         the  third and the lateral ventricle communicate by the for-
         amen of Monro.   The pineal gland is entangled in its pos-
         terior part, being placed below it, and is generally torn from
         its peduncles when the tela is raised up.   It is at this point
         that the tunica arachnoidea may be traced into  the cavity
         of the lateral ventricles.
            The Plexus Choroides, which was stated to  bound the
         tela choroidea on each side, and to descend along the hippo-
         campus major to the  fissure of Sylvius, or rather to ascend
         from this point, and to terminate in the vein on the side of
I         the  middle line of the tela, is narrow  at its termination, but
         increases continually in breadth as it is traced towards  its
         commencement.  The middle part, however, where it makes
         its turn, is an exception to  this rule, for there it is larger
         in every way than elsewhere; its vessels being  more capa-
         cious and more tortuous.   Precisely  at this point, a vesicle
         is very frequently found, considered  by some as a hydatid
         of the brain;  in some cases it is filled with calcareous mat-
         ter  instead  of with  water.   The Glandulae  Pacchioni, as
         stated, also prevail at this margin.
            On the under surface of  the tela choroidea, adhering: to it,
         there is on each side a small venous plexus which goes from
         before backwards, and terminates in the vena galeni, near
         its junction  with its fellow.  It receives the blood of the
         third and of  the fourth ventricle.*
            There is also the same sort of plexus in the fourth ventricle.
            Upon  the removal  of the Velum Interpositum, or its ele-
         vation, the pineal gland will be found entangled under  its
         posterior margin, and the whole upper surface of the thalami
         optici is  exposed; the third  ventricle is also brought into
         view, of which much  has  already been said in speaking of
         the parts which constitute  it.
           The third ventricle is placed  immediately between the
         thalami optici.  It is a narrow oblong cavity, bounded below
         by the pons tarini, crura cerebri and the eminentiae mam-

                         *  Meckel, Manuel D'AnatonuV.
            Vol. IT.—47 
370
NERVOUS SYSTEM.
millares, and above by the velum interpositum and the for-
nix.  The anterior crura of the  fornix are at its fore part,
and just before them is the anterior commissure (Commis-
sura Anterior.)  This  body is  a  transverse fasciculus of
medullary matter, which  passes from one hemisphere to
the other through the anterior margins of the thalami optici.
Its middle part is rounded and free, but its extremities pe-
netrate into the substance of the anterior inferior portion of
the corpus striatum, and spreading out gradually, describe
a curve with its  convexity forwards, which terminates on
each side  in the  taenia  hippocampi of the  inferior cornu of
the lateral ventricle.  This fasciculus, in penetrating the
corpus striatum does not mix with  its substance, but in the
early part of its course goes in a canal formed in the latter.
In order to see this arrangement a  part of  the corpus stria-
tum must be removed.  The anterior commissure resembles
a nerve in its structure, as it is surrounded by a very deli-
cate sheath, and is divided into fasciculi of fibres.
  Just behind and below the anterior commissure, the base
of the infundibulum opens into the third ventricle; this place
is the Iter  ad Infundibulum. At the posterior extremity of
the third  ventricle, just  below the posterior  commissure
which has  been described as a process of the  pineal gland,
the communication exists with the fourth  ventricle.   This
passage is  the Aqueduct of Sylvius,  and  leads obliquely
downwards and backwards under the valve of the brain.
   The third ventricle communicates freely with the lateral
ventricle through the aperture called the Foramen of Mon-
ro, which  is situated precisely at the place where the plexus
choroides terminates; that is to say, under the anterior crus
of the fornix.   Doubts  have, from  time to time, been sug-
gested in  regard  to  the natural  existence of this commu-
nication; it only requires a moderate degree of accurate ob-
servation to dispel them; they have arisen, probably, from
the aperture being shut up by the occasional adhesion of the
the plexus choroides to  the  contiguous surface of the brain.

   The Fourth Ventricle (Ventriculus Quartus, Cerebelli)
has been, in a great degree, described in the account of the 
NERVES OF THE ENCEPHALON.
371
neighbouring parts; it will, therefore, be very readily un-
derstood on the present occasion.  It is an irregular tri-
angular cavity,  the base of which is downwards.   It is
bounded in front by the tuber annulare and the medulla ob-
longata, behind by the fundamental portion of the cerebel-
lum, and above by the valve of the brain and the tubercula
quadrigemina; it is under the latter that the communication
between it and the third ventricle is found. Its lateral pa-
rietes are formed  by the medullary prolongations from the
cerebellum to the  tubercula quadrigemina.  This  cavity, as
stated, is open below, when that portion of pia mater is re- '
moved, which passes from the cerebellum to the medulla
oblongata.
   From what has now  been  said of the connexion of the
pia  mater with the ventricles, it will be readily understood
that as their surfaces are covered by  pia mater, and the re-
moval of it exposes  their cavities, they are, in fact, conti-
nuations of the external .surface of the brain.


     SECT. VI.—OF THE NERVES OF THE ENCEPHALON.

   The more improved  observations of  modern  anatomists
having pointed out the fallacy of considering the brain as the
source of the spinal  marrow, instead of the reverse,  it will
follow that the proper order of describing the nerves of the
encephalon, will  be successively from the spinal marrow.

   The Hypoglossal Nerve (Nervus Hypoglossus, or Ninth
Pair) arises from  the medulla oblongata,  by several fascicu-
li placed one above the  other.  The roots of these fasciculi
spring from the fissure which separates  the corpus pyrami-
dale from the corpus olivare.   The  fasciculi  are from four
to eight in number, being subject to  vary in  different indi-
viduals.  They unite into two  or three trunks, which co-
alesce into one after  penetrating the  dura mater by distinct
openings;  and then proceed through  the anterior condyloid
foramen of  the occipital bone.
   The general distribution of this nerve is to the muscles
of the tongue. 
37*
NERVOUS SYSTEM.
   The Accessory Nerve (Nervus Accessorius, Eighth Pair)
arises from the posterior fasciculus of the Medulla Oblon-
gata, just behind  the nervus hypoglossus, and also from the
posterior fasciculus of the Medulla Spinalis, sometimes as
low down as the seventh cervical nerve.   There are six or
seven roots  from  the  medulla spinalis, and  about  three or
four from the  medulla oblongata; the former are single, and
run successively into the same trunk;  but the latter are each
composed of two branches, consisting respectively of two
filaments.   These roots are successively larger and longer
as they ascend to join the common trunk.   The latter goes
up between  the posterior  fasciculi of spinal  nerves and the
ligamentum denticulatum, and gets  into the cavity of the
cranium, behind  the vertebral artery through  the  foramen
magnum occipitis.
   This nerve varies in respect to the  number of its roots,
and the mode  of  their origin.   In all cases the trunk thus
formed passes  from the cranium through  the foramen lace-
rum posterius, traversing there the dura mater in a sheath
common to it and to the  pneumogastric  nerve, but some-
times it has  its own particular opening behind that of the
latter.
   Its general distribution  is to the muscles and  to the inte-
guments of  the neck.

   The Pneumogastric Nerve (Nervus  Pneumogastricus
or  Vagus, Eighth Pair) arises from the corpus restiforme
of the Medulla Oblongata, just behind or on the borders of
the fissure separating it from the Corpus Olivare, somewhat
above  and posterior  to the highest  root of the accessory
nerve.   It commences by a number of parallel filaments,
varying in number from ten to fifteen, which are placed very
near each other, so as to form two or three flattened  fasciculi
of half an inch or more in length.  The fasciculi below ad-
here to the spinal accessory, and those above to the glosso-
pharyngeal nerve. The fasciculi  finally collect into a sin-
gle flattened cord of one and a half lines in breadth.
   This cord goes outwards and backwards to the foramen 
              NERVES OF THE ENCEPHALON.           373

lacerum posterius, and gets through it in front of the inter-
nal jugular  vein,  being separated  from the latter by the
small spine which arises from pars  petrosa of the temporal
bone.  It passes through its own canal in  the dura mater,
being thus kept distinct from the  glosso-pharyngeal, and
from  the accessory nerve, and  in  this canal the  fasciculi
which form it are collected  into a single cylindrical trunk.
After getting through the canal it  then adheres by a close
strong cellular substance, to the glosso-pharyngeal and to the
accessory.
   The general plan  of distribution of the Pneumogastric
Nerve is, as its name implies, to the organs  of respiration
and to the stomach.

   The Glosso-Pharyngeal Nerve (Nervus Glosso-Pharyn-
geus, Eighth Pair) arises from the posterior cord of the me-
dulla oblongata,  just above, and somewhat anterior to the
superior filaments of the last nerve, with  which it is very
closely connected.  Its filaments, which are  five or six  in
number, spring, therefore, from the anterior  margin of the
corpus restiforme, or from the fissure separating it from the
corpus olivare, under the posterior margin of the tuber an-
nulare.
   Its filaments soon  collect  into a  round cord, and anasto-
mose even in the cavity of the cranium by  a considerable
branch with the pneumogastric.  It  runs outwards and back-
wards to  the foramen lacerum posterius, and goes through
the same  division of  it that the  pneumogastric does, but in
its own canal of the dura mater.   About half an inch from
this canal it enlarges within  the cranium, into a small ob-
long ganglion of  five or six lines long which extends itself
as far as the foramen lacerum.*
   Its general distribution is to the tongue and to the  pha-
rynx,  as  its name implies.
   The three last  nerves have been erroneously  considered
as but  one,  probably  in consequence of their going out of

  * Tins ganglion is described by Andersech and by Huber, but its exist-
ence is questioned by Bichat. 
374
NERVOUS SYSTEM.
the cranium together, and of their being placed so near each
other in this cavity.  A very general name for them collec-
tively has been that of the Eighth Pair.

  The Auditory Nerve (Nervus Auditorius;—Acusticus;
—Portio Mollis) arises in  part from  the medullary  striae
on the surface of the  calamus  scriptorius, and partly  from
the corpus restiforme, between the glosso-pharyngeal nerve
and the tuber  annulare.   At its  origin it is so extremely
soft as not to bear handling, and is too pulpy to present the
appearance of fibres;  but  becoming  more distant from the
medulla oblongata,  it is harder and fibrous.
  This nerve is impressed on its  internal face by a longitu-
dinal  furrow for the  reception  of  the  facial  nerve.    It
passes obliquely forwards and outwards beneath the crus ce-
rebelli, and penetrates into the meatus auditorius internus.
It adheres somewhat near its root to the under anterior mar-
gin of the cerebellum, just behind the crus of the latter; the
circumstance is considered by J.  F.  Meckel, as a proof of
its having there another origin, whereby an  analogy is es-
tablished between it and the two other nerves of the senses,
to wit, the optic and the olfactory.
  The distribution  of this nerve is confined to the labyrinth
of the ear.

  The Facial Nerve (Nervus Facialis, Portio Dura Sep-
timi, Par Septimum) is placed in  front of and above the
auditory nerve.   It arises by two branches, which are per-
fectly distinct from each  other and  differ much  in  their
size.  The larger one,  which is placed within and above the
other, arises from the medulla oblongata  at the most supe-
rior part of the corpus restiforme, where the latter runs into
the tuber annulare.   The origin of the nerve is sometimes
overlapped by the latter, so that some few of its  fibres ap-
pear to come  from the annular  protuberance, while they
only pass  through it, in their course from the medulla ob-
longata.   The second branch,  which is much smaller than
the other, arises, by three or four filaments, from that por- 
NERVES OF THE ENCEPHALON.
375
tion of the medulla oblongata which is placed between the
first branch and the auditory nerve.
  The two branches of the facial nerve are kept distinct for
the distance of several  lines  before they  unite.  Proceed-
ing outwards and backwards, they reach the meatus audito-
rius internus, and then proceed, as a single  cylindrical trunk,
through the aqueduct of Fallopius, to emerge  at the stylo-
mastoid foramen, for the purpose of being distributed upon
the muscles and skin of the head.
  The auditory nerve and the  facial compose the seventh
pair of writers.

   The Sixth Pair of Nerves (Par Sextum, Motor Oculi
 Externus) is found four or five lines distant from the facial
 nerve, and at its internal  side.  It arises from the  base or
 upper extremity of the corpus  pyramidale, under the pos-
 terior margin of the tuber  annulare;  when  the latter is
 broader than usual, some of  the fibres  seem to come from
 it; but the appearance  is deceptious, as they only penetrate
 it.   The fibres are assembled into two roots, of which the
 internal is three or four times as large as the other.
   These  roots,  before they penetrate the dura mater, most
 commonly unite into a single trunk, which goes almost di-
 rectly forwards, and is enveloped in a neurileme.  Passing
 through the  cavernous  sinus,  it gets into the orbit by the
 sphenoidal  fissure, and is spent  upon the abductor  oculi
 muscle.

   The Nervus Trigeminus (also called Trifacial,  Par Quin-
 tum) is one of the largest among those  that proceed from
 the  basis of the brain,  and  emerges from the  side of the
 pons varolii, just where it is continuous with the crus  ce-
 rebelli.   It is composed of three roots:  an anterior, a pos-
 terior,  and  a middle;* of which the  latter  is much the
 largest.
   The Middle  Root is about a line and  a half in breadth,

   * Santorini, Observ. Anat. Venitia, 1724.  Soemmering, de Corp. Hum.
 Fabrica, torn. iv.  Gall and Spurzheim, Anat. Du.  Cerv. 
376
NERVOUS SYSTEM.
and has a passage made for it by the very obvious splitting
of the superficial fibres of the pons varolii.  It is composed
of thirty or forty fasciculi, which are divisible into a hun-
dred  or  more fibres.   These fasciculi  may be traced into
the substance of the tuber annulare, (but intersected by the
transverse fibres of the latter,) in the direction of the fourth
ventricle.  When they have come near the latter, they may
be traced thence into  the  medulla oblongata, towards the
fissure that exists between the corpus olivare and restiforme.
It is  at this  point, that  the greater  number of the  fibres
arise; some from the corpus olivare, and others from the fis-
sure.
  The commencement of this root is pulpy and destitute of
fibres, and  is surrounded by grayish  substance; but when
it has  advanced  into the pons, it  is  surrounded  by a fine
membrane, and  is very evidently fibrous.  There is a suc-
cessive increase  in  its  size, from its commencement till it
is ready to emerge from  the pons, when it becomes some-
what contracted, and immediately afterwards increases again
considerably in  size.   It then enters a canal of the  dura
mater at the fore part of  the petrous portion of the tempo-
ral bone, and just behind the cavernous sinus.  This canal
sets but loosely about it at first, but afterwards it adheres to
the surface of the nerve.
  The middle root of  the nervus trigeminus, in the upper
part of the canal of the  dura mater, preserves its fasciculated
appearance, and  many  small filaments are interchanged be-
tween the fasciculi, so as  to make a complex net-work. But
at the lower part of the canal, in the dura mater, it is con-
verted into a ganglion of a semilunar shape, with its concavi-
ty upwards, having about six or eight lines in length, and
one and a half in breadth.  This body, (called the Ganglion
of Meckel, Ganglion Semilunare,  Plexus Gangliformis) is
compact, and has its fibres very much  matted above, but be-
low they assemble into larger and  more distinct fasciculi,
which are afterwards arranged into three principal trunks,
departing from the cranium through different foramina; to 
NERVES OP THE ENCEPHALON.
377
wit, through the sphenoidal fissure, the foramen rotundum,
and the foramen ovale.
  J. F. Meckel asserts that the filaments of the plexus above
the ganglion, for the most part terminate in a gutter formed
in the  superior margin of the ganglion, and that there are
but very few of them which can be traced into  the trunks
below.   The trunks below consequently arise from the cir-
cumference of the ganglion.
  The two smaller roots of the  nervus trigeminus proceed
out of the tuber annulare at different points, from that of the
large root, and each one has its  appropriate fissure for that
purpose.   One, from its  situation, is called Anterior, and
the other Posterior.  Each may be traced into the posterior
cord of the  medulla oblongata, but not so far as the large
middle toot, and is formed by several fasciculi of medullary
fibres.   The Anterior and the  Posterior roots,  after going
separately for six or eight lines, unite to form a single cord.
This cord does not merge itself in the semilunar ganglion,
but continues distinct from it* with the exception of send-
ing off to it a few fibres, it afterwards gets from the cranium
through the foramen rotundum, and is distributed to some
of  the muscles of mastication,  as  the  temporal and bucci-
nator.
   The general distribution  of the fifth pair of nerves, or
the trigeminus, is to the orbit,  to the face,  and  to  the
tongue.

   The Pathetic Nerve (Nervus Patheticus, Par Cerebrale
Quartuum, Fourth Pair) is the smallest which comes from
the encephalon, and is not larger than a sewing  thread.   It
arises by two filaments or roots from the upper anterior face
of  the  valve of the brain, just below the testes.   This ori-
gin is soft, and easily broken from  the want of a neurileme,
but the latter is soon afterwards furnished.
   The nervus patheticus  appears on the base of the brain,
between the cerebellum and the posterior lobes of the cere-
brum, at the external  margin of the  tuber annulare.   It

     ■ In this respect the fifth pair resembles one of the spinal nerves.
   Vol. II.—48 
J7S
NERVOUS SYSTEM.
then goes for some distance along the margin of the tento-
rium till it comes near the posterior clinoid process; it then
penetrates into a canal of the dura mater, and reaches the
orbit of the  eye through the sphenoidal  fissure, to be dis-
tributed on the superior oblique muscle.

   The Third Pair (Par Tertium, Nervus Motor Oculi)
arises from the internal face of the crus cerebri, about two
lines in advance of the anterior margin of the tuber annu-
lare.   Its roots come in great part from the cineritious mat-
ter which is  found on this surface of the  crus, and may be
traced  for some  distance upwards  and  backwards along the
parietes of the third ventricle.   The nerves of the  opposite
sides are in contact for some distance by the internal faces
of their roots, but do not adhere.
   The Nervus Motor Oculi proceeds from its origins to-
wards the external  margin of the  cavernous sinus, and pe-
netrating into the orbit through the sphenoidal  fissure, it is
distributed to most of the muscles  of the eyeball.

  The Optic Nerve (Nervus Opticus, Par Secundum) is
about the same  size with the trigeminus.  It arises by a
broad flattened root, one portion of which comes  from the
posterior end of the thalamus opticus,  and another from the
testis through the  means of a medullary band that passes
from the latter towards the thalamus of the same side.  From
this point the optic  nerve winds forwards under the crus ce-
rebri, adhering to it,  and inclining inwards towards its fel-
low.   Its adhesion  to the crus is considered by many ana-
tomists as another of  its  origins.
   The Optic Nerve having reached the under anterior part
of the third ventricle,  adheres so closely to its fellow that the
two seem fused together, in  such a way that there is no line
of separation between them.   This junction receives above,
from the third ventricle, some medullary filaments, which
Meckel feels authorized to consider as another origin.  The
junction presents the form of the letter X, and is called the
chiasm or crossing  of the optic nerves.   The most distin-
guished anatomists, however, have laboured in vain to set- 
NERVES OP THE ENCEPHALON.
379
tie  the  question of this mode of junction;  some believing
that there was only a lateral union, others that the nerve of
one side crossed over to the other side, and others, again,
that the decussation occurred  only with some of  the fibres,
but not all.  Observations, in comparative anatomy, on blind-
ness, and indeed on every conceived mode of elucidation,
have been resorted  to  without  producing a solution of the
problem; but the discussion of their merits would require
too much space for the present  work.
   The Optic Nerves as they approach their chiasm become
more cylindrical, and  continuing so afterwards, penetrate
into  the orbits through the foramina optica.   It is only in
front of their junction that they are invested by a  neurileme,
which, having considerable firmness,  penetrates into  their
interior and divides them into distinct canals.

   The Olfactory Nerve (Nervus  Olfactorius,  Par  Pri-
mum) is situated on the under  surface  of the anterior lobes
of the brain, near the fissure that separates the hemispheres.
It  goes forwards from  its root,  and also converges gradual-
ly towards its fellow, so as to reach the cribriform plate of
the ethmoid bone, through  the perforations of which it
passes out.  In its course, it  is lodged in a small furrow, by
which pressure upon it is prevented.
    This nerve  arises by three medullary fasciculi, or roots,
from the basis of the brain at the corpus striatum, in the fis-
sure of Sylvius, where the anterior and posterior lobes join
each other; these roots are from eight to  twelve lines on
the outer side of  the infundibulum.   The  roots  are placed,
in regard to each other, diverging; one is within, another
in the  middle, and  the third  external.   The external root
is the longest, and arises from  the  extreme  posterior mar-
gin of the  anterior  lobe by its last convolution.  It  has a
curved course from without inwards, the concavity of which
is  forwards and the convexity backwards.  The internal
root  is concealed by the chiasm of the optic nerves, and
arises from the adjacent surface of the anterior lobe.   The
middle root comes from the posterior margin of the anterior
lobe by the cribriform  surface,  which is between the  other 
380
NERVOUS SYSTEM.
two roots.   These origins unite to form a single prismatic
cord,  which increases in size as it advances forwards, and
consists of medullary and cineritious longitudinal fibres
mixed together.
  The anterior extremity of the olfactory nerve is swollen
out into what is called the bulb, (Bulbus) and  sends from
its under surface filaments, which, surrounding  themselves
with a tunic from the dura mater, penetrate  into the nose
and spread themselves on the schneiderian membrane.   In
its whole  length it  is exceedingly soft and  pulpy, till it
gets out of the cranium.
      SECT. VII.—OF THE ARTERIES OF THE BRAIN.

  The arteries of the brain, or pia mater,  are derived from
the two internal carotids, and from the two vertebrals.

  The Internal  Carotid Artery (Carotis Interna) gets into
the cavity of the  cranium through the carotid canal of the
temporal bone,  conforming itself of course to the curvature
of this canal, and being brought by it to the posterior part
of the body of the sphenoidal bone.  In escaping from the
petrous bone it has to ascend,  and also  to advance some-
what, by which it  is brought to  the posterior part of the
sella turcica. From this point it goes horizontally forwards
through the cavernous sinus,  and  reaching  its fore part, it
then ascends again, and  towards  the fissure of Sylvius.
While in the carotid  canal,  it  gives a small branch to the
tympanum of the ear, and as it lies on the side of the sella
turcica it gives  off the anterior and the posterior arteries of
the cavernous sinus.  When ii  reaches the anterior clinoid
process it sends off a  large branch  through the  optic fora-
men to the parts  contained  within the orbit of the  eye.
This branch is the ophthalmic artery, and what remains of
the internal carotid is then distributed to the brain after the
following order.
  There are, first of all, some  small branches sent to the 
ARTERIES OF THE ENCEPHALON.
.381
adjacent parts, as the pituitary gland, the infundibulum,
and the lower part of the third ventricle.
  The Arteria Communicans  Posterior is directed back-
wards and inwards,  and runs into the corresponding trunk
of the basilar artery called  the posterior cerebral.   There
are some varieties in regard to the size and precise point of
origin of this trunk, which  it would be needless to mention
particularly.  Besides the important anastomosis formed by
it, it  detaches several ramuscles to the adjacent parts of the
pia mater.
   The  Arteria Choroidea is the next branch from the inter-
nal carotid.  It goes outwards and backwards, and after de-
taching some minor branches, it penetrates into the inferior
cornu of the lateral ventricle, by the side of the Pons Va-
rolii, and expends  itself in ramifications upon the plexus
choroides.
   The Arteria Callosa, or Anterior Cerebri, is detached from
the internal carotid, opposite the last.  It advances in front
of the union of the optic nerves, converging rapidly at the
same time towards its fellow.  Just before  the chiasm of the
optic nerves, a transverse branch passes between it and its
fellow.   This branch, the  Arteria Communicans Anterior,
is of variable length and size in different subjects,  being
sometimes a line, and on other occasions three or four.lines
long.
   The arteria callosa then keeps near its fellow on the under
surface of the hemisphere, giving out small branches; and
having got on a  line with the anterior margin of the corpus
callosum, it ascends on the flat side of the hemisphere, and
divides into anterior and into posterior twigs.  The former
supply the fore flat  part of the hemisphere; the latter the
corpus  collosum and the  adjacent  surface of the  brain.
These several branches of  the arteria anterior  reach as far
as the upper convex surface of the brain, and  there  anas-
tomose with other arteries.
   The Internal Carotid may now be considered to have lost
 its name, and the trunk is continued as Arteria Cerebri Me-
 dia.   It is directed outwards, and engages in the fissure of 
382
NERVOUS SYSTEM.
 Sylvius; while there it detaches a great number of branches
 to the adjoining surfaces of  the  anterior and of the middle
 lobes.  Some of these branches are of considerable magni-
 tude, and winding along the convolutions of the brain, they
 at length  ascend to the upper  surface of  the hemisphere,
 and anastomose with the branches of the anterior and of the
 posterior cerebral artery.

   The Vertebral Artery (Arteria  Vertebralis) is  a branch
 of the subclavian.   In order to reach the cavity of the cra-
 nium it has to traverse  the foramina of the transverse pro-
 cesses of the six upper vertebrae of  the  neck.   It ascends
 in a straight line till  it reaches the second  vertebra, but
 there, in order  to pass through the transverse  process, it
 takes a direction upwards and outwards.   It then ascends
 vertically again  till it  has passed  through  the  transverse
 process of the first vertebra.   After which it takes a hori-
 zontal course winding around the posterior face of the up-
 per  oblique  process of the same vertebra, in a depression
 for the purpose, and having reached the internal extremity
 of this process, it ascends upwards and inwards through the
 occipital foramen into  the cavity of the cranium; perfora-
 ting the dura mater just above  the condyle of the occipi-
 tal bone.   Having got into  the cranium, it is first on the
 side and then on the under surface  of the medulla  oblonga-
 ta, and  continues to approach its  fellow till it reaches the
 posterior margin of the  tuber annulare.  At this point the
 two  vertebral arteries coalesce, and from their union results
 the basilar artery.
  The vertebral artery in this course, from  its origin to its
termination,  detaches several arterioles to the heads of the
adjoining muscles, to the membranes of the spinal marrow,
and to the nerves as they come out of the intervertebral fo-
ramina; they are generally too small and irregular to de-
serve a special description.  At its upper extremity, how-
ever, it sends off three  branches of some consequence; the
 Spinalis Posterior; the Spinalis Anterior;* and the  Inferior
 Cerebelli.
              * See Arteries of Medulla Spinalis, 
            ARTERIES OF THE ENCEPHALON.          383

  The Arteria Inferior  Cerebelli, divides shortly after its
origin, or otherwise  is  double from  the  beginning.   The
most posterior truik  is distributed about the bottom of the
fourth ventricle, on the fundamental portion of the cerebel-
lum, and the  contiguous faces of the two  hemispheres or
lobes of the latter.   The other trunk of this artery is dis-
tributed on the under surface of  the cerebellum.
   The Basilar Artery (Arteria Basilaris)  is on the middle
line of the tuber annulare, and extends from its posterior to
its anterior margin.   In this course  it detaches some arte-
rioles to the tuber; others to the  meatus auditorius internus,
(Arteriae Auditivae Internae) which are  spent upon the la-
byrinth, and  anastomose with twigs  from  the internal and
external carotids.  At its anterior extremity it detaches on
each side two considerable trunks; first, the superior artery
of the  cerebellum, and  immediately afterwards the poste-
rior artery of the cerebrum.
   The Arteria Superior Cerebelli goes outwardly from its
origin just behind the anterior edge of the tuber annulare,
until it gains the front  margin of the  cerebellum.   It then
divides into several branches, some of which are distributed
 on the upper surface of the  cerebellum and run to its poste-
 rior margin, where  they anastomose with the branches of
 the arteria inferior; others  are spent upon the substance of
 the cerebellum near its anterior edge.
    The Posterior Artery of  the Cerebrum (Arteria Cerebri
 Posterior) one on each side, is the termination of  the ba-
 silar artery.  It proceeds abruptly outwards, and has gone
 but a few lines when it receives the  arteria  communicans
 posterior  of the  internal  carotid.   It then continues out-
 wardly parallel with the anterior margin of the tuber annu-
 lare, and  near it crosses the crus cerebri, and is then distri-
 buted  on the inferior, and on the posterior part  of the
 hemisphere, and of  the corpus  callosum.  As mentioned
 its  branches  anastomose with those of the anterior and of
 the middle arteries.

    It will  now be understood, that an arterial circle encloses 
384
NERVOUS SYSTEM.
the chiasm of the optic nerves  and the corpora albicantia.
The fore and lateral parts of the circle, are  formed by the
internal carotids and their branches, while the hind part is
formed by the Basilar Artery and its  bifurcation.  This is
the circle of Willis, and  establishes a very  free communi-
cation  between the vessels of the two sides of the brain.
  The veins of the Brain  have been sufficiently alluded to
in the account of the Pia Mater, and of the Sinuses of the
Dura Mater. 
BOOK  IX.
                      PART III.

                        Senses.

  To the /peripheral portion of the nervous system, belong
all the nerves which are sent off from the Medulla Spinalis
and Encephalon, as well as the Sympathetic.  Some of these
nerves have a special  apparatus attached to their external
extremities, for the purpose of augmenting and facilitating
their appropriate  powers of sensation; of this class are the
Optic, the Olfactory, and  the Auditory.  Others of them, as
the nerves of the tongue and of the skin,  though they are
the means  of special  sensations,  yet the apparatus  upon
which they are spread is applied  to  many purposes, more
striking and useful, than that of indicating the presence of
surrounding  bodies.   And lastly,  the remaining nerves
being by far the most numerous and large, are distributed
to the muscles and to  the viscera.
                     CHAPTER  I.

        OF THE EYE AND  OF ITS DEPENDENCIES.

  The organ  of vision, which depends upon the optic nerve
for  its usefulness, is formed  by the Ball of the Eye and
many Dependencies or Auxiliary parts, all of which are si-
tuated within the orbit, and fill up its cavity.
  Vol. II.—49 
386
NERVOUS SYSTEM.
     SECT. I.--OF THE AUXILIARY PARTS OF THE EYE.

  The Eyelids (Palpebrae) are placed at the anterior orifice
of the orbit, and serve to shut out, by their closing, the light
from the eye, and also, by their frequent motions, to sweep
the front of the  eyeball, so as to remove, from its transpa-
rent part,  moats and dust.  They are distinguished into
upper  and lower, and  the place, at  each  end,  where the
horizontal fissure between them ceases, is called their Com-
missure, Angle, or Canthus. The angle next to the nose, or
the internal, is  called the Great  one, and the other, the
Litte one.
  The Internal Canthus is united to the nasal process of the
superior maxillary  bone by a rounded  tendon (Ligamen-
tum Palpebrale Internum,) which passes horizontally in-
wards, and is nearly half an inch in length. It throws the
skin into a small  ridge, which  may be distinctly seen and
felt at this point.  The External Canthus is held in place by
its general attachments of cellular substance and  by  the ex-
ternal palpebral  ligament.
  The upper eyelid is somewhat larger than the lower, but
the structure of both is the same, for each one  is formed by
skin externally; next to it a plane of muscular fibres, being
the orbicularis palpebrarum;  then  a plate of cartilage; and
lastly,  a thin membrane uniting it to the eyeball.
  There is nothing in the texture of the skin  of the eyelid
which  needs description in a  more particular manner, than
that of stating its fineness, its thinness, the looseness of its
attachment to the muscle beneath by long yielding  cellular
substance, and the deficiency of adipose matter.  It is ren-
dered prominent at the superior margin of the orbit, both
by the projection of the bone there, and by the presence of
the corrugator supercilii  muscle at its internal extremity.
This prominence is furnished with  an  arched cluster of
hairs, (Supercilia,) which have  their loose ends inclined
horizontally outwards, and are rather  more abundant at the
root of the nose  than externally. The supercilia of the two 
EYE.
387
sides are separated commonly by a small bare space called
Glabella, the existence of which adds much to the calm and
intellectual expression of the human countenance; whereas
the junction of the two eyebrows, by the hairs filling up
this space, gives a gloomy, and occasionally  a ferocious ap-
pearance.
   The margins of the eyelids are also furnished with hairs,
(Cilia,) the roots of which are insinuated between the skin
and the tarsus cartilage.   The  hairs of the  upper  lid are
longer and more numerous than those  of the lower; they
are concave  upwards, while the latter  are  concave down-
wards,  so  that the convexities of the two ranges of hairs
 come in contact when the eyelids are closed. The hairs of
 each cilium are disposed into three or four rows, by which
 a long brush is formed, the central hairs  of which are longer
 and larger than any others.
    The hairs of the supercilia and of the cilia resemble one
 another strongly, for when  examined closely each one will
 be found to have a  bulbous soft root, just beyond which
 there is a narrow part.  The middle of the hair is swollen,
 and its external extremity is brought to a fine point. These
 hairs correspond in colour with the hairs of the head.
    When the orbicularis muscle  is removed, a ligamentous
 or fibrous membrane is found passing from the external mar-
 gin of the orbit to the corresponding margin of  the palpe-
 bral cartilages, and  separating the eyelids  from the parts
 contained within the orbit.  There is a partial decussation
 of the fibres of this membrane, from the external commissure
 of the  cartilages to the external edge of the  orbit; it has
 more firmness than any other part of the membrane, and is
 the external palpebral ligament, (Ligamentum Palpebrale
 Externum.)  On the side of the internal canthus of the orbit
 there is no corresponding ligamentous expansion, but a few
 irregular  fibres, which  allow the masses of fat beneath to
 project forwards between  their fasciculi.
  The Palpebral Cartilages (Tarsi) are two in number, one
at the margin of each eyelid, to which they communicate a 
388
NERVOUS SYSTEM.
 smooth, even surface from the internal to the external com-
 missure.   They are between the orbicularis muscle and the
 tunica conjunctiva.  The upper one is larger than the lower,
 resembles an oval cut in half in its long diameter, and is
 about six lines broad in  its middle;  the  lower one is of a
 breadth, nearly uniform of about two lines.  Their internal
 extremities cease just before they reach the puncta lachry-
 malia, and  are connected with the internal palpebral liga-
 ment, which has been described as one of the origins of the
 orbicularis oculi muscle connecting it with the nasal process
 of the  upper maxillary bone;  their  external extremities
 cease just before their commissure, and are firmly attached
 to the external palpebral ligament.
   These cartilages are thicker where they form the margin
 of the  eyelids, and  have there a slope or bevel, by which
 when in contact, a small groove is formed on their posterior
 surface.   From their resistance  to  the concentric contrac-
 tions of the orbicularis, they keep the eyelid smooth  and
 favour its sliding upon the eyeball.  Certain animals, being
 destitute of these  cartilages, when they wink, the skin by
 the contraction of the orbicularis,  is drawn up like the mouth
 of a purse.

  Conjunctiva.—Below the palpebral cartilages is the fourth
 layer of the eyelid, the conjunctiva.  It is white, thin, and
 diaphanous, in the uninflamed state.  Beginning at the roots
 of the cilia, where it is continuous with the  skin, it covers
 the posterior face of  each  eyelid, is reflected  for  eight or
 ten lines towards the bottom of  the orbit, and then passes
 to the eyeball, of which it covers the anterior  half, not ex-
 cepting the cornea.   It penetrates into  the lachrymal ducts,
 to be continuous with the lining membrane of the lachrymal
 sac.
   From this description, it is  evident that the tunica con-
junctiva has one surface presented against itself when the
 eyelids are closed; this surface is lubricated and very smooth,
 so as to permit a free motion of the lids and ball of the eye.
 The other surface is connected in its anterior half by cellu-
 lar substance to the eyelids, and in its remaining part to the 
EYE.
•i8'J
ball of the  eye, by the  same means.  It is united rather
loosely to the sclerotica till  it gets near the margin of the
cornea; but to the latter it  adheres so firmly, and changes
there so much its own texture, that it seems like a portion
of the cornea.
   This membrane, from its continuity with the skin and the
lining membrane of the nose, from its sympathies with them,
from the nature of  the discharge from  it,  and from its ex-
treme sensibility, is ranked by Bichat among the mucous
membranes.  It has,  however, some  peculiarities  in its
structure, for it is entirely deficient in villosities, and though
most abundantly furnished with capillary vessels, they do
not admit red blood, but in a state of irritation.

   Glandulae Palpebrarum.—These bodies, also called the
glands of Meibomius, from  an anatomist who has described
them particularly, are situated at the margin of each eyelid,
between its cartilage and the conjunctiva.  They are about
two or three lines long,  and appear  like small, white, ser-
pentine threads, running at  right angles to  the  margin of
the  lid, near to, and parallel with one another.  They are
more abundant on the upper than on the lower lid.  They
terminate by a row of small orifices in the margin of the lid
just behind  the cilia. For preventing the overflowing of the
tears,  and  the sticking together of the eyelids,  they dis-
charge an unctuous fluid, which may be made manifest by
squeezing them.  Their secretion is occasionally much  aug-
mented, and then has a large  quantity of serum and glu-
tinous matter in it; in this case the evaporation of the serum
makes it adhesive,  and causes  the eyelids to adhere  after
they have been closed for some time, as in sleep.

  The Musculus Levator Palpebrae Superioris is placed in
the superior  part of the  orbit.   It arises by a small round
tendon from the upper margin of the optic foramen, and be-
coming fleshy, it expands itself into a long thin triangle, of
which  the base is in front.   It covers the rectus superior
muscle.
  Terminating in front by a thin tendinous expansion, it is 
390
NERVOUS SYSTEM.
 inserted into the superior margin of the upper palpebral car-
 tilage; but some of its fibres continue on between the latter
 and the orbicularis to the lower^dge of the cartilage.
   It raises the upper lid, by drawing it towards the bottom
 of the orbit.


                Muscles of the Eyeball.

   There are six muscles concerned in moving the eyeball,
 four of which, from their direction, are said to  be straight;
 and the other two, for the same reason, are called oblique.
 With the exception of the  inferior  oblique, they all arise
 from the bottom of the orbit.

   1.  The Rectus Oculi  Superior, being placed immediately
 below the levator palpebrae, arises from the superior margin
 of the optic foramen, and from the contiguous part of the
 optic nerve.   It  runs  forward, increasing somewhat  in
 breadth, and  is  inserted by a broad thin tendon  into the
 sclerotica, two lines from the cornea.
  It turns the eye upwards.

  2.  The Rectus Oculi  Externus arises from the  external
 margin of the optic  foramen.   It then advances along the
middle of the  external wall of the orbit, to the periosteum
 of which it adheres slightly, and is finally inserted, by a thin
broad tendon,  into the external side of the sclerotica, about
two or three lines  from  the cornea.
  It abducts the eye, or turns it outwards.

  3. The Rectus  Oculi Inferior arises also from the optic
foramen  at its inferior margin, and lying upon the floor of
the orbit as it  advances  forwards,  it is inserted tendinous
into the under surface of the sclerotica, two lines from the
 cornea.
  It depresses the eye,  or turns it downwards.

  4.  The Rectus  Oculi Internus arises from the internal
 margin of the optic foramen, and goes forwards along the 
EYE.
391
internal wall of the orbit, being separated from it by a layer
of adipose matter.  It is inserted, by a tendinous expansion,
into the inner side of the sclerotica, two or three lines from
the cornea.
   It adducts the eye, or turns it inwards.

   5.  The Oliquus Oculi Superior is placed along the upper
internal angle of the orbit.   It arises from the correspond-
ing margin of  the optic foramen, by a small round tendon;
it then advances  forwards, and when  it has got near the
margin of  the orbit,  it is converted into a long round ten-
don.
   The tendon passes through a cartilaginous loop which is
formed for it, just at the inner margin of the supra orbitary
foramen, and is connected to the loop by long loose cellular
substance,  which  permits it  to  play freely  backwards and
forwards.   The tendon from  this point changes its direction
by going  backwards  and outwards; it also becomes more
flat, and is then  inserted into the upper face of the sclero-
tica, near its middle, just beneath the internal margin of the
rectus superior muscle.
   This muscle is  the longest, but the most delicate of those
belonging  to  the eyeball.   According to  Soemmering,  it
draws the eyeball forwards,  and towards  the  internal can-
thus, and  directs  the pupil towards the cheek.   By the aid
of the inferior oblique, it draws the  eyeball  towards the
nose: it expresses pride: it appears to  be  greatly excited in
anger.*

   The precedimr muscles are all connected, either directly
or indirectly,  with the theca of the optic nerve.

   6. The Obliquus Oculi Inferior  is  at the bottom of the
orbit.  It arises,  by a small  tendinous beginning, from the
upper maxilla at the side of  the  os unguis, and increasing
in size, it goes below the rectus inferior outwards and back-

   * Bulbum in priora et angulum internum versus movet; pupillam deor-
sum ad genam dirigit; juvante musculo obliquuo inferiori bulbum nasum
versus trahit; animi fastum exprimit; ira valde commoveri videtur. 
392
NERVOUS SYSTEM.
 wards, and gets between the eyeball and the rectus exter-
 nus.  It is then inserted into the outer face of the sclerotica,
 about half way between the optic nerve and the cornea.
   It causes the eye to revolve on its axis, and turns the ball
 towards the  nose.  Its action, however, is much modified by
 that of the other muscles.


             Of the Lachrymal Apparatus.

   The  apparatus for the tears (Organa Lachrymalia, viae
 Lachrymales) consists in  the Lachrymal Gland, the La-
 chrymal Ducts, the Lachrymal Sac, and a few other parts.

   The Lachrymal Gland  (Glandula Lachrymalis) is situ-
 ated in the orbit, immediately below and within the external
 angular process of the os frontis.   It secretes  the moisture
 that lubricates the eyelids and eyeball, and which, when
 it becomes abundant, is called the Tears.   It  is a flattened
 oblong  or oval, convex above and concave below, of ten
 lines  in length, six in width, and  about two  lines at its
 thickest part, for its edges are somewhat beveled.   It may
 be considered as divided into two parts or lobes, of which
 the superior  is the larger and occupies the depression  attri-
 buted to it in the frontal bone, while the inferior, being the
 smaller, is placed at the anterior margin of the depression.
 It is lined below by the conjunctiva, and is protected in front
 by the margin of the orbit which it touches.
  This gland resembles much the salivary in its light pink
 colour,  and in its consisting in a congeries of lobules united
by cellular substance.  Unless we are to consider the latter
as such, it has no  regular  capsule.   From  the lachrymal
gland, there proceed six or seven excretory canals, extreme-
ly fine,  and found with so much difficulty that  many distin-
 guished anatomists have  sought  for  them in vain.*  The

  * These are Morgagni, Haller, Zinn, and Duverney. Meckel, Soemmer-
ing, and many others, speak with all confidence concerning them.  Bichat
admits that he only acknowledges their existence inductively. Dr. Monro,
of Edinburgh, claims to have discovered them by plunging the eye into a 
EYE.
..93
 orifices of these ducts have been laid down, by Soemmering,
 as equi-distant, forming, in the conjunctiva, a row half an
 inch long, and parallel with the superior margin of the tar-
 sus cartilage, beginning a quarter of an  inch above its ex-
 ternal end, and going inwards. I have, on several occasions,
 supposed myself to have passed bristles into these orifices,
 but, after the  doubts expressed by Bichat,  am disposed to
 hesitate in the opinion of the real direction which the bris-
 tles took.  One fact is certain, that, by squeezing the gland,
 small  drops, like tears, will appear on the nearest surface of
 the conjunctiva, but not in the regular order laid down  by
 anatomists for the  lachrymal orifices.

   The Lachrymal  Ducts (Canaliculi Lachrymales) are si-
 tuated immediately beneath the skin, at the internal  com-
 missure of the eyelids, in their posterior  margin, and be-
 hind the  orbicularis muscle.  There is one for each eyelid.
 They are about an  inch  long, though the lower one is rather
 longer than the upper.
   The lachrymal ducts commence  at a  small elevation of
 the margin of each eyelid, bordering immediately upon the
 internal end  of the tarsus cartilage, but perfectly distinct
 from it.  This elevation is conical, and points towards the
 ball of the eye; in  its centre is a very small foramen, called
 the Punctum Lachrymale, which is  the beginning of the la-
 chrymal duct.  The punctum is about a line in length, and
 enlarging in  its course, it  runs at right angles to the duct
 into which it empties,  of which  it may be called the Orbital
 Orifice; the upper one will, therefore, ascend, and the lower
 one descend.
  The lachrymal ducts are much larger than the puncta, be-
ing, in their whole course, about one line in diameter.  At
their orbital extremities, they go rather beyond the puncta,
so as to form  a small cul-de-sac.  These canals  converge,
and having got to  the internal angle of the eyelid, they
are there  placed behind the  internal palpebral  ligament.

coloured fluid which was absorbed by them. Dr. W. Hunter seems to have
a prior claim to Dr. Monro.  Scv Med. Comment, p. 54.
  Vol. IT-— 50 
.m
NERVOUS SYSTEM.
They then discharge, by distinct orifices, but very near each
other, into the lachrymal  sac at  its external anterior part,
where they form a small round projection  in the interior of
its cavity, and are overlapped, sometimes,  by a small dupli-
cature of its lining membrane.  When the eyelids are closed,
the lachrymal ducts are horizontal and nearly parallel, but
when the eye is open the upper duct is elevated, and there-
by becomes oblique; it is hence more proper for the intro-
ductipn of instruments into the  lachrymal sac.

  The Lachrymal Caruncle (Caruncula  Lachrymalis) is
placed precisely in the angle formed by the internal junction
of the eyelids.  It is a red coloured tubercle, differing in size
in different individuals, but commonly as  large as a grain of
wheat.   It is conical, and obtains its redness from the con-
junctiva, being reflected over it:  when accurately examined,
it will be found to consist  in a group of sebaceous glands, of
which, according to some anatomists, there  are seven, ranged
two in a row, and one on the top  of the others.  The surface
of this body is beset with very fine hairs, and the orifices in
it are distinguishable with a glass.

  The Semilunar Valve, or Fold, (Plica  Semilunaris,) is
situated immediately at the ocular margin of the caruncle.
It has the form of a triangle, the point of which runs into the
caruncle, and the base, which is somewhat crescentic, is di-
rected towards the ejre. It is a duplicature of the conjuncti-
va, which becomes very manifest from behind, and, in some
cases,  has its base furnished with a very small strip of  car-
tilage.*  I have seen  several cases of the kind very well
marked: they occur more frequently in the African, accord-
ing to my personal experience.  Between the base and the
caruncle it is formed  into a number of loose wrinkles, which
disappear when the eye is very much abducted.
  This body,  in the human subject, is evidently intended
to permit to  the  eye a great freedom of abduction.  Its
analogy, however, with the third eyelid of animals is very
striking, and the  difference is rather in the full develop-
                        * Meckel. 
395
ment of the latter, than in the organization.  It is very
properly remarked by J. F. Meckel, that in descending the
scale of animals, the third eyelid  is always in an inverse
ratio to the other two, till it ends by being a  complete sub-
stitute for them.

   Surrounding the caruncle may be observed a depression
on the adjoining part of the plica semilunaris.   Into this
depression the puncta lachrymalia are  directed and there
play up and down;  the  tears  accumulate in it, from which
cause the depression is called Lacus Lachrymalis.

   The Lachrymal Sac (Saccus Lachrymalis) is placed at
the  internal  canthus of the orbit; in the depression of the
 os unguis, and of the nasal process of  the upper maxillary
 bone.  It is an oblong cylindroid cavity; and extends from
 the transverse facial suture to the anterior extremity of the
 inferior meatus of the nose, being concealed there by the
 anterior part of the inferior turbinated  bone.  It is crossed
 at its front part  by the tendon of the orbicularis, which
 with a few fibres of this muscle adheres to it.
   The course of the lachrymal sac is, at  first, slightly for-
 wards in its descent to  the  nose,  but  when it reaches the
 lower part of the orbit, it is afterwards slightly backwards,
 so that in its course it may be considered  as forming an ob-
 tuse angle forwards.   It  also decreases somewhat in  size
 from above downwards, and at its lower orifice is flattened
 from  side to  side.
   The lachrymal sac consists in two  membranes, an exte-
 rior fibrous one continuous with the periosteum of the con-
 tiguous bones; and an interior one which is thick, villous,
 of  a red colour, and abounding in mucous follicles.  The
 interior is continuous above with  the lachrymal ducts, and
 below with  the Schneiderian membrane.   On a line with
 the floor of the orbit, this internal membrane is thrown into
 a circular duplicature,  considered by  some anatomists  as
 forming the proper boundary of the lachrymal sac; all be-
 low this is called by them nasal canal.  The distinction is
 rather arbitrary, and in some degree hurtful to clearness  of 
J96
NERVOUS SYSTEM.
description; a much better plan is to call the part above the
valve, the orbital portion of the sac; and the part below the
valve, its nasal portion.  Sometimes there is a second valve
about three lines below the first, and also another at the
nasal orifice, formed by a duplication of the Schneiderian
membrane.
   The Tensor Tarsi is a small muscle on the orbital face of
the lachrymal sac, and of which I gave a detailed account
some few years  ago.*   It arises from the posterior superi-
or part of the os unguis, just in advance of the vertical su-
ture between the os planum  and the os unguis.   Having
advanced three lines, it bifurcates; one bifurcation is insert-
ed along the upper lachrymal  duct,  and terminates at its
punctum, or near it; and  the lower bifurcation has the same
relation to the lower lachrymal duct.  The base of the ca-
runcula lachrymalis is placed  in the angle of  the bifurca-
tion.   The superior and the inferior margins of the muscle
touch the corresponding fibres of the orbicularis palpebra-
rum, where the  latter is  connected with  the margin of the
internal  canthus of the  eye,  but may  be readily distin-
guished by their horizontal course.   The nasal face of this
muscle adheres  very closely to  that portion of the sac
which it covers, and  also to the lachrymal ducts.  The
lachrymal sac rises about a line above its superior margin,
and extends in the orbit four lines below its inferior margin.
The orbital  face of the muscle  is covered  by a  lamina of
cellular membrane, and between this lamina and the ball of
the eye are placed the valvula semilunaris, and a considera-
ble quantity of adipose matter.
   As the bifurcated extremities of the  muscle follow the
course of the ducts, they are covered by the tunica con-
junctiva.  When this muscle is examined from behind, the
eyelids being in situ, it becomes obvious that it is concave
on its orbital surface, and consequently convex on the nasal;
that the  muscle  is an oblong body, half an inch in length,
and about three  lines wide, bifurcated at one end; and that
it arises much deeper from the orbit than any acknowledged

       * Philadelphia Journal of Med. and Phys. Sciences, 1821. 
EYE.
397
origin of the orbicularis.   The superior fork, however, has
a few of its fibres blended with the orbicularis.
  In  regard to the use of this  muscle; its  attachment to
the posterior face of the  sac  is such,  that it draws the or-
bital parietes of the sac away from the nasal, and dilates the
sac, owing to the nasal face of the latter being fixed to the
bones.   As this muscle has  a cylindrical  concavity on its
orbital side, it is  evident that when it contracts the fibres
become  straight, or nearly so, like  the fibres  of the dia-
phragm, and the cavity of the sac is enlarged after the same
manner  as the cavity of the  thorax.   A tendency to a va-
cuum being thus produced  by it, the valves or folds of the
internal  membrane of the  sac permit the vacuum  to  be
filled more readily through the puncta than from  the nose;
and the  puncta being continually bathed in the  tears of the
lacus lachrymalis, both in the waking and in the  sleeping
state, the tears are constantly propelled through them by
atmospheric pressure.   The  evacuation of  the sac  is no
doubt accomplished by its own  elasticity,  and  by the con-
traction  of  the orbicularis;  probably in  a  chief degree  by
the latter,  because in persons who have epiphora, or a ten-
dency to obstruction in the nasal duct, the accumulation of
tears and matter principally takes place at night,  when the
action of the orbicularis  is suspended by sleep.   For these
reasons  we should argue, that this little muscle  is  active
at all times, both night and day.   To Dr. Physick I am in-
debted for  suggesting  another use for  it; to  wit, that of
keeping the lids in contact with the ball of the eye   Some
persons  possess unusual voluntary power of this muscle, of
which I  have seen two examples;  one in a  lady; another in
a gentleman, a student of medicine.   In each instance the
individual  could shorten so much  the internal angle of the
eyelids,  as to  conceal it, along with the puncta, in the in-
ternal canthus  of the orbit*

  * Having laboured, first of all, to convince the profession of the exist-
ence of this muscle, the next step, as is usual on such occasions, was to
vindicate my own  pretensions to its discovery, and to attempt to remove
such objections as required attention. For the arguments on this subject
I refer to the Philadelphia Journal of Medical  and Physical Sciences, of
i 
398                 NERVOUS SYSTEM.
               Of the Nerves of the Orbit.

   In addition to the optic  nerve,  there are several belong-
ing to the eye and to its auxiliary parts; they are derived
from the  Motor Oculi or third pair; from the Trochlearis,
or fourth  pair; from the  first branch of the Trigeminus, or
fifth pair; and from the Motor Oculi Externus or sixth pair,
For an account of which, see Nerves.


              Of the  Arteries of the Orbit.

   The Eyeball and its auxiliary parts are principally sup-
plied by  the Ophthalmic Artery, which  as was  mentioned
in the account of the  Brain is a considerable  branch  given
off by the Internal Carotid at the fore part of the Sella Tur-
cica.   This branch gets into the orbit on the outer side of
the optic nerve through  the  optic  foramen, and, after a
short course, crosses obliquely above the optic nerve, so as
to get to  the internal side of the orbit.   It sends off a great
many small trunks, which are very inconstant both in their
size and origin; they are as follow:

   1.  Arteria Lachrymalis arises, commonly, soon after the
ophthalmic has got into the orbit: it goes forwards between
the rectus superior and the rectus externus muscle, to which
it distributes arterioles; it then reaches the lachrymal gland,
and having left branches  with  it, what remains issues out at
the external angle of the eye, so as to supply the contigu-
ous part of the upper eyelid.
   2.  Arteriae Ciliares.  According to Soemmering, before
the origin of the lachrymal artery, the ophthalmic detaches
from one  to three ciliary, which penetrate into the ball of

Nov. 1824, edited by Professor Chapman. My claims have been unequivo-
cally admitted by Messrs. Breschet and Jourdan, of Paris,  anatonusts of
unusual distinction, in the translation which they have made  of J. F. Mec-
kel's Manual of Anatomy, vol. iii. p. 219; by Gery, in  the Melanges de
Cuirurgie etrangere, Geneva,  182-t, p. 415; and  by Professor Giuseppe
Trasmondi,  in the Arcadica Journal of Rome, vol. xix. p. 1. 1823. 
EYE.
399
the eye near the optic  nerve.   Other arteries of the same
class arise subsequently from the ophthalmic, and occasion-
ally some of them  from the lachrymal itself.  They go to
the choroid coat of. the eyeball and to the iris.
   3. The Arteria Centralis Retinae arises  from among the
cluster of ciliary arteries, and like them has no invariable
root.   It penetrates the optic nerve about  the middle of its
orbitar  section, and going  in its centre gets into the eye
through the cribriform  part of the sclerotica.  It is then
distributed  by ramuscles to the retina, to the tunica hya-
loidea, and  to the capsule of the lens.
   4.  The Arteria Ethmoidea Posterior  is  inconstant in ex-
istence,  and comes at one time  from the  trunk, at another
from a  branch of  the ophthalmic.  It passes over the supe-
rior oblique muscle, and penetrating through the posterior
orbitary foramen, is spent by arterioles upon the neighbour-
ing part of the dura mater, and upon  the posterior ethmoidal
cells, where it anastomoses upon the Schneiderian mem-
brane, with branches from the internal maxillary.
   5.  Arteriae Musculares:  Of these there are two; one of
them, the inferior, sends branches to the rectus internus, rec-
tus inferior, and obliquus inferior oculi, also to the lachrymal
sac, and to the parts about the bottom of the orbit. It occa-
sionally detaches  some of the ciliary arteries. The superior
muscular branch is also called the supra orbitar. It supplies
the muscles of the superior part of the orbit, and then issuing
through the supra orbitary  foramen,  it is spent in arterioles
upon the os frontis and its periosteum, and upon the orbicu-
laris oculi,  corrugator supercilii, and occipito frontalis.   It
anastomoses there with other branches of the ophthalmic,
and with the temporal artery;
   It is  usual for the anterior  ciliary  arteries, to come from
the muscular branches.

   The  Ophthalmic  Artery, after having  detached all the
aforesaid branches, is much diminished  in volume, and ad-
vancing along the internal parietes of the orbit, its next
branch  is 
400                 NERVOUS SYSTEM.
   6.  The Arteria Ethmoidea Anterior, which dips into the
 anterior internal orbitary foramen, and is divided into small
 branches, some of which are  spent upon the adjacent por-
 tion of the  dura mater, others upon the frontal sinus and
 the anterior ethmoidal cells. Some of these branches pene-
 trate from the cranium through the cribriform  bone into
 the nose, and ramifying upon the Schneiderian membrane,
 anastomose with the internal maxillary.
   7.  The Arteriae Palpebrales are two in number;  they
 come sometimes from a common trunk, and on other occa-
 sions arise separately.  One is the Superior, and the other
 the Inferior; the latter arises first, and is distributed to the
 conjunctiva,  the caruncula  lachrymalis, lachrymal sac, and
 finishes  by many small branches to the lower eyelid, that
 anastomose with the infra-orbital artery, so as to form the
 lower tarsal arch.   It  also anastomoses with the lachrymal
 artery by its extreme  branches.
   The Superior Palpebral Artery also distributes branches
 to the conjunctiva, sac, and caruncle; it then emerges above
 the palpebral ligament, around the margin of the superior
eyelid, and  forms,  along with the lachrymal and the supra
 orbital artery, the  superior tarsal  arch, which  distributes
 small branches, in great profusion, to the orbicularis mus-
 cle, and to the structure generally of the  lid.  It anastomoses
 externally with the lower palpebral artery.
   8.  The Arteria Nasalis is sometimes a well marked con-
 tinuation of the ophthalmic.  It passes out of the orbit at its
internal canthus, above the internal palpebral ligament, and
anastomoses at the  root of the nose with the facial artery.
It is distributed to  the side of the nose, and to the lower
part of the forehead.   Its chief contribution to the  eyelids
is at the internal end of the orbicularis, where it anastomoses
with the palpebral arteries.
   9. The Arteria Frontalis  passes  out of the orbit, at the
upper part of the internal canthus.   It is quickly divided
into branches, which  go to  the orbicularis  and corrugator
muscles, to the occipito-frontalis, and to  the frontal sinus. 
EYE.
401
               Of the Veins of the Orbit.

   The blood distributed to the eyeball and to its auxiliary
parts, has two routes for returning to the  heart, one through
the cavernous sinus of the brain, and the other by the super-
ficial veins of the face.  As a general rule, all the branches
of the ophthalmic artery which reach the eyelids, or become
otherwise superficial, return their blood by the latter route;
and those whose distribution  is to the ball of the eye and to
the parts deeply seated in the orbit, return their blood by
the sinus.
   When the  veins are well injected, a very considerable
number is manifested in both eyelids.  They form a hand-
some network, the meshes of which are small and numerous,
and commence by small roots at the margin of the eyelids.
The vessels of this network becoming  successively larger
from the centre to the  circumference  of the  orbicularis,
cover the whole surface of the latter, and from the thinness
of the skin are readily seen beneath it.   The veins of the
lower  eyelid  are discharged into the facial vein, where it
borders on the orbicularis,  and the veins of the upper lid
being bordered along the superior margin of the orbicularis
by a horizontal  branch  of  the temporal vein,  discharge
themselves into it.

   The Ophthalmic Vein (Sinus  Ophthalmicus) is the large
trunk within  the orbit which receives successively the re-
maining blood of the  eye, and  passing  along  the internal
parietes of the orbit, crosses over the optic nerve, and pene-
trates through the optic foramen into the cavity of the cra-
nium, where it terminates in the cavernous sinus.   It may
be considered as  commencing by an anastomosis with the
facial vein at the internal  canthus; it then receives the fol-
lowing  branches:
   1. The nasal, which arises  from the parts about the inter-
nal canthus of the eye.
   2. The anterior  ethmoidal, which comes from the nose
and frontal sinus.
   Vol.  II.—51 
402                NERVOUS SYSTEM.
  3. Branches from the recti and obliquui muscles.
  4. The lachrymal  vein, from the  lachrymal gland and
levator palpebrae muscle.
  5. Posterior ethmoidal vein, from  the nose.
  6. The ciliary veins, or those of the choroid coat, which
are very numerous.
  7. The central vein of the retina, which is collected from
three or four principal branches, and follows the course of
the artery of the same name, through  the cribriform part of
the sclerotic coat, and through the centre of the optic nerve.
The trunks of this vein anastomose, at the anterior margin
of the  retina, with those of the Ciliary Body.

  There are, of course, frequent anastomoses between the
veins of the eyelids and the primitive branches of the oph-
thalmic vein.

          SECT. II.—OF THE BALL OF THE EYE.
  The Eyeball (Bulbus  Oculi) is situated within the ante-
rior half of the orbit, from which it is kept separated by its
auxiliary parts, and  by a large quantity of adipose matter
which fills up their interstices.  It it very nearly spheroi-
dal, but not so much so as to prevent its antero posterior
diameter, which  is  about an  inch long, from exceeding in
measurement every other.  Such is the general opinion of
anatomists,  but from some recent experiments, made by
distending the eye with mercury, I  have been induced to
doubt its correctness, and especially in the African; for in
the latter I found the transverse diameter to exceed the an-
tero-posterior  by a line or more.
  It is formed by a series of concentric tunics, one invest-
ing the other, and by humours  contained within those tu-
nics.   Of the former the Sclerotica and the Cornea are  ex-
ternal, the Choroidea and  the  Iris next, and the Retina is
internal; of the latter the Vitreous Humour  is by far the
most abundant, and constitutes a principal  part of  the eye-
ball, being situated in its  posterior  part; the  Crystalline
Humour is  in front of the vitreous;  and  the  Aqueous is
placed between the crystalline and the Cornea. 
THE BALL OF THE EYE.
403
         Tunics or Membranes of the Eyeball.

  The  Sclerotic  Coat  (Tunica Sclerotica,  Albuginea)
forms  about five-sixths  of the exterior  investment of the
eyeball, the remaining sixth of which is obtained from the
cornea.  At its posterior part it is joined by the optic nerve;
this junction does not occur precisely at its axis or centre,
but at  the  inner side of it.   When the optic nerve is de-
tached at this junction, a small round hole is perceptible in
the sclerotica, or rather  it is more frequently perceived as
a thin  cribriform  lamella, through the holes of which the
pulpy part of the  optic  nerve passes, so as to  get within
the eye.   This cribriform lamella, or the appearance of it,
is no doubt  produced artificially by the nerve being com-
monly cut through very near  the eye, and, as Mr. Jacobs,
of  Dublin, very properly suggests, should be considered as
the most anterior termination,  or the point of the optic
nerve, instead of as a portion of the sclerotica.  The neu-
rileme of the optic nerve is so arranged, that small  round
longitudinal canals are left, Which contain the nervous mat-
ter; from this cause  it happens  that a thin section of the
optic nerve in any part of its course in the orbit, will,  if
held up to the light,  manifest the same cribriform  arrange-
ment with the part alluded to.   This  part of the structure
of the optic nerve  will be  readily understood by the  Ame-
rican student, in comparing it with the  pith of the Indian
corn-stock, which, being traversed longitudinally, by many
fibres, upon the drawing of them out, an  equal number of
longitudinal canals is left in their places.
  At its fore part,  the edge of the sclerotica for its  junc-
tion with the cornea, is bevelled  all  around; and though
nearly  circular, is not completely so, from its horizontal
diameter being somewhat  greater than any other.  There
are  several orifices of inconsiderable size scattered over the
sclerotica, some of which are oblique and others direct; they
transmit the  blood vessels  and nerves.   The  sclerotica is
nearly a line in thickness  at its  back part, from which it 
104                NERVOUS SYSTEM.
gradually becomes reduced to half that thickness in front,
wher* it. is strengthened by the tendinous insertions of the
recti muscles.  Its internal surface is smooth and somewhat
shining, being loosely attached to the cellular substance in-
tervening between it and  the choroid coat; but the exter-
nal surface is rough  and  more obviously fibrous, being at-
tached somewhat strongly to all the adjoining parts.
   This membrane  is of a white colour, and consists of a
single layer, whose structure  is essentially fibrous.  The
fibres  are very closely compacted, and  compose an inter-
texture which cannot be unravelled.  It is so closely united
to the dura mater covering of the optic nerve, that many
anatomists, notwithstanding its greater thickness, are  dis-
posed to  speak of it as a continuation of the same.  Its
strength and its want of elasticity suit it remarkably to main-
tain the form of the eye, and to resist injuries.   Out of the
many blood vessels that penetrate it, but few ramify in its
structure, and the existence of nerves in it is  by no means
very evident.
   The tunica arachnoidea follows the course of the optic
nerve, within its coat of dura mater,  and forms, just around
the cribriform plate or foramen of the sclerotica, a circular
pad; it is then reflected on the internal face of the sclerotica,
as far as its anterior opening.  It is this which causes the
internal face of the sclerotica to be smooth and shining, and
thereby to correspond with that of the dura mater.*  This
circumstance is more readily proved in a very young eye,
than in the adult one.

   The Cornea, as mentioned,  fills  up the  aperture  at the
fore part of the sclerotica, and, of course, has the same dia-
meters, measuring thereby more transversely than in any
other direction.  It is a  segment of a smaller sphere than
the sclerotica, and is consequently more convex than it. Its
thickness  is uniform, and commonly exceeds  that  of the
 sclerotica at the fore part of the latter.

   * J. F. Meckel.  Zinn supposed this surface to be derived from the pia
mater 
THE BALL OF THE EYE.
405
  Its circumference adheres very closely to the sclerotica,
and presents a bevelled or oblique edge,  which is inserted
into the corresponding bevel of the sclerotica, so that the
latter includes the former.   The  closeness of this junction
induced the older  anatomists to consider these membranes
as one and the same, notwithstanding their obvious diffe-
rence of structure and of properties.   Their adhesion yields
to protracted maceration.   The cornea is covered in front
by a  continuation of the  tunica  conjunctiva, which unites
the eyeball to the eyelids.   This may be proved  by dissec-
tion, by maceration, and by its sloughing off entirely along
with the epidermis of animals that are subject to this pro-
cess, as the locust, snakes and others.   On its posterior face,
it is covered by the membrane of the aqueous humour, which
may be rendered  evident by steeping it  in spirits of  wine,
whereby the latter membrane is made more hard, and may
be torn off.
   The cornea, in a natural state, is  perfectly transparent,
and readily transmits the rays of light.   It consists of an
 indefinite  number of laminae, which  are placed one against
the other like the leaves of a  book, and are united by a de-
 licate transparent cellular  substance which  permits the la-
 minae to slide upon each  other.  These laminae are kept
 moist  and pellucid  by an interstitial secretion of a fluid
 equally pellucid with themselves, the abundance of  which
 in health gives to the eye its brilliancy, and the deficiency
 of it in illness and in death causes the eye to look dim and
 somewhat opaque.   Its evaporation,  which no doubt is con-
 tinually occurring, is as constantly supplied by a fresh and
 abundant  secretion.  The motion of the eyelids  sweeps the
 residuum, after the evaporation of its watery particles, from
 the surface of the cornea; without this process, the residuum
 appears as a thin layer or film of albuminous matter  spread
 over the cornea,  when the eye is kept open without wink-
 ing for a considerable time.
    The cornea has not the fibrous structure of the sclerotica,
 yet the application of mechanical force to the eyeball shows
 that it is stronger.  Neither has it  vessels conveying  red 
406                 NERVOUS SYSTEM.
 blood naturally, yet, in a state of inflammation, its capilla-
 ries  dilate so as to  admit red blood, and deposite coagu-
 lating lymph between Us layers.   It is common for anato-
 mists to attribute a want of sensibility to it  in a natural
 state; as a genernl rule, this is fallacious:  for many persons,
 where the eyes are not inflamed, suffer extremely from its
 being cut  in cataract, and  sometimes  faint from  the pain,
 while others are truly unconscious of the incisions made
 through it.   Of this opinion, I have a full assurance from
 repeated observations on the practice of Dr. Physick, as
 well as in instances in my  own hands.

   The Choroid  Coat  (Tunica  Choroidea,  Vasculosa) is
 placed immediately within the circumference of the sclero-
 tica, and is of equal  extent.   At  its posterior part it fur-
 nishes, for the passage of  the optic nerve, a singular annu-
 lar opening, the  margin of which is somewhat thickened
 and perfectly distinct from the pia mater investment of the
 nerve, from which some anatomists have desired  to trace
 this coat.  The anterior opening of the choroid is bounded
 by the ciliary ligament and by the iris.   On its outer side
 may be seen an abundance  of that loose flocculent cellular
 substance which joins it to the sclerotica.   Internally, it is
 spread over the retina, but does not adhere to it.
   The choroid coat is closely fastened, at its anterior mar-
 gin, to the corresponding part of the sclerotica, by a  ring
 which surrounds it, of a short compact cellular tissue.  This
 ring, called the Ciliary Ligament,  (Ligamentum Ciliare,
 Orbiculus Ciliaris,)  is from a line to two lines in breadth,
 and  may  be readily  distinguished by  its  whiteness, con-
trasted with the dark colour of the choroid. It is intimately
united to the latter, and seems to form a part of its struc-
ture, whereby it is caused to detach itself entirely from  the
sclerotica and to adhere, by preference, to the choroid when
these two membranes are separated. *  The iris is set in the
front margin of the ciliary ligament,  so that the sclerotica

  * Fontana asserted that a circular canal was to be found in this ligament;
many examiners have failed in finding it, and its existence is denied. 
THE BALL OF THE EYE.
407
and the cornea may be peeled from the choroidea and iris,
without impairing the continuity of the two latter.  Just
beyond the junction of the two last, the ligament presents
a small ridge or elevation all  around, which is fitted into a
corresponding fossa at the circumference of the internal face
of the cornea.
   The internal face of the choroid coat, as well as its ante-
rior margin, undergo a very  remarkable change  from the
general plan of  this tunic, by  forming what is  called the
Ciliary  Body (Corpus Ciliare, Corona Ciliaris.)   In or-
der to see this in the most favourable manner, the eye should
be laid on the cornea, and its posterior half cut  away.  It
will then  be evident, that just behind the iris, and within
the circumference of the ciliary ligament, the internal face
of the choroid coat forms a considerable number of radiated
folds or little ridges, which converge from behind forwards
and inwards.  These folds commence by striae, almost im-
perceptible to the naked eye, which are in contact with the
fore part of the vitreous humour and with the canal of Pe-
tit, and thereby  not only impress the neighbouring portion
of the tunica hyaloidea with their shape, but even leave
upon it the black pigment with which they themselves are
covered. These folds, when they get near the circumference
of the iris, coalesce one with  another, and terminate in a
considerable number (from fifty to sixty, according to Soem-
mering) of processes, (Processus Ciliares,) the central ex-
tremities of which are loose, and float in the aqueous hu-
mour.  Some of these processes are longer than others. As
a whole, the ciliary processes constitute a ring of radiating
filaments,  which are a  line or more in length, placed along
side of, and  in contact with, one another; the external peri-
phery of the ring adheres to the ciliary ligament, and through
it to the greater circumference of the iris, so that the rino*
appears, but fallaciously, to be continuous with the iris.  In
certain animals, as the sheep,  the radiated appearance of the
iris, on its posterior face,  favours this notion still more.
The  internal periphery  of the ring  presents the  central
ends of the filaments detached from one another,  and of a 
408                 NERVOUS SYSTEM.
 downy appearance;  with the handle of a knife they may
 be  readily  pushed backwards and  forwards.   Generally
 speaking, the ciliary processes are so much  concealed  by
 the iris, that they cannot be seen in the living body through
 the cornea; in cases,  however, of extreme dilatation of the
 pupil by narcotic applications, their central extremities are
 brought into view.
   The choroid coat always appears, when uninjected, of a
 very dark brown or black colour, arising from a black paint
 (Pigmentum Nigrum) being very thickly spread over the
 whole of that surface of it which is adjacent to the retina,
 and being also diffused through  its thickness.   This  paint
 is more abundant near the  iris than posteriorly, being laid
 on there in flakes, in the intervals between the ciliary striae,
 and tinging also the ciliary processes.  It may be removed
 in a considerable degree, indeed almost entirely, by mace-
 ration, or by careful washing with a camel's hair pencil.  It
 is supposed to be an exhalation from the vessels.  Its par-
 ticular colour is of a most durable kind.   According to the
 observations of Bichat, the long continued action of  light
 upon it, when transferred  from  the  choroid  to a piece  of
 paper, does not affect it; neither is it changed by being sub-
 mitted to very strong chemical agents, as sulphuric, muri-
 atic, or nitric acid, alcohol, or caustic potash.  This degree
 of indestructibility of colour is an invaluable property, and
 almost singular; for it is well  known to the keepers of me-
 dicinal articles, that the colours of all of them yield to the
 continued  influence of light,  and that  they also become
 weaker by the same cause.

  In regard to structure, the choroid coat is thin, soft, and
 easily lacerated: when cleared of its pigment by maceration,
 it is semitransparent, and is then seen evidently to consist of
 but one lamina; unless we may be disposed to consider as a
 second one the pigment naturally on  its internal face.   It
 has no appearance of fibres in its composition, but when in-
jected  seems to consist almost wholly of arteries and  of
 veins. 
THE BALL OF THE EYE.             409
  The arteries are branches of the ophthalmic, and are called
ciliary.  There are two Long Ciliary Arteries, which pene-
trate the sclerotic coat not far  from the optic nerve,  and
pass, one of them  on the  external and superior part of the
choroides, and the other on its inferior and nasal side, to the
front of the eye.   In this course, they do not send off any
branches of consequence  till they reach the iris,  on which
they are distributed.  The Short Ciliary Arteries  are much
more numerous than the others, and also smaller; their num-
ber sometimes amounts to twenty; the most of them pene-
trate the sclerotica from behind, near the optic nerve also.*
They quickly divide into a great number of branches, which
depart  at very acute angles and have frequent anastomoses
with one  another.  These branches run forwards  nearly pa-
rallel, and, at the fore part  of  the choroides, form a very
intricate intertexture, which is continued upon the ciliary
processes, and communicates with the vessels of the iris.t
   The  Veins of the Choroid Coat are also extremely abun-
dant.   They run from before backwards, and the branches
which concur to form them,  being adjacent with and parallel
to each other for the most part, form large curves, the con-
vexity of which  is  forwards; they moreover anastomose
freely, and thereby  produce  a vascular  sort of  net work,
 filling up the concavity of some of the curves.  These veins,
 called the Vasa Vorticosa, are nearer the external surface
 of the  choroides  than the  arteries, and are assembled into
 twelve or fourteen trunks, which, engaging in the scleroti-
 ca, near its middle, run for some distance in its  substance,
and then, by their junction, are reduced to four  or five in
 number.   The latter, disengaging themselves from the eye,
join subsequently the ophthalmic vein.
   In addition to the veins mentioned, the long ciliary arte-
 ries have their venae comites, which observe a course parallel
 to and adjoining them.  These veins do  not observe the
 vortical arrangement of the others, and bring back the blood
 of the iris; they terminate, however, in the larger trunks of
 the others.
    * Sammering, Icones Oculi Humani.                f Idem.
   Vol. II.—52 
410                 NERVOUS SYSTEM.
   This structure has been most  cautiously explored by the
 celebrated  Soemmering, and  his observations have tended
 very much to determine the opinions of anatomists concern-
 ing many parts of the eye.  A curious remark of his is, that
 "the human eye may be distinguished from that of animals
 by a form of this vascular net work, entirely peculiar: for
 example, in the eye of the  ape, its vascular tissue differs not
 only from that of the human subject, but also from that of the
 dog, and still more evidently from that of the calf.   From
 which cause, it would be as easy to distinguish  with  a mi-
 croscope, the choroides, well injected,  of different animals,
 even a piece of only  the forty-eighth part of an inch  in ex-
 tent, as it  is easy to distinguish a poplar strippe I  of its
 leaves from an oak, a  pear tree, an apple, or any other tree,
 by the arrangement of its trunk  and branches."
   The Choroides,  on its internal  face, is not smooth, but
 velvety, which becomes still more conspicuous when the eye
 is finely injected and examined with a microscope. Meckel
 considers the appearance to depend upon its very fine tissue
 of vessels.   This surface is called  Tapetum.  In the bullock,
 at a particular  part of it, this  surface presents a shining,
 silvery appearance, and may  be  torn off from the external
 surface.   Ruysch attributed two laminae to the membrane
 in the human subject, the internal of which  was called after
 his name, but the distinction is now generally abandoned.

   The Iris is a circular plane placed  at the front of the cho-
 roides, and having, in its centre, a round opening called the
 pupil (pupilla.)  Its external circumference is attached to
the ciliary ligament, and by it to the  choroid coat,  and is
precisely at the junction of the cornea  with the sclerotica.
Professor Soemmering has  bestowed much  attention  in as-
certaining whether this membrane is perfectly flat or some-
what convex in front, and, by repeated observations care-
fully made,  has assured himself  that it is flat. *   My  own
 observations and preparations have  induced me to believe
 that  in many cases it will be found slightly convex in front,
* Icones Oculi Humani. 
THE BALL OF THE EYE.
411
as Petit assorted more than a century ago.   In a moderate
state of dilatation, its  nasal or internal border is somewhat
narrower than its external or temporal. With the exception
of its external  circumference, every part of the iris is free
from any attachment;  by which arrangement it moves freely
in the aqueous humour, so as to contractor dilate  its pupil,
according to the quantity of light admitted upon the eye.
  The iris, with the exception of its central or  pupillary
circumference,  where it is thinner than elsewhere, is much
thicker than the choroid coat. The posterior face of the iris,
sometimes called uvea, is covered in great abundance with
pigmentum nigrum.  When this is removed by maceration,
which may be  readily done, the membrane becomes  semi-
transparent.   Its anterior surface is the seat of the colour,
which characterises every individual's eyes.  There are  but
two of these colours, light blue and orange,  the predomi-
nance of one or the other of which, assisted  by the dark
ground on the  back  of the iris, gives the cast of hue to  the
eye.  The front surface, when examined on  the living eye
with the microscope, is seen to be downy or flocculent, and
 is traversed  by filaments forming an intertexture, some of
 which are circular, others oblique; and others radiated.
   The power which  the iris has of dilating the pupil when
 there is but little light,  and of contracting it  when there  is
 much, has induced many anatomists to think that it is formed
 of muscular radiated fibres, which by their contraction pro-
 duce the first motion, and of circular ones which produce the
 last.  Among  these anatomists may be mentioned, Ruysch,
 Morgagni, Zinn, Sabatier. Ruysch asserted that the radiated
 fibres extended from the greater circumference of the  iris  to
 the pupil, and were  fixed there by very delicate tendons.
 The late Doctor Monro, of Edinburgh, has described particu-
 larly the circular fibres, and a  preparation of the bullock's
  eye which belonged to  him is still exhibited there,  where
  these fibres are seen around the margin of the pupil.   The
  several fibres can only be seen distinctly,  when the pigmen-
  tum nigrum is washed away.   Demours and Meckel deny
  the existence of the  radiated fibres.  The late distinguished 
412
NERVOUS SYSTEM.
Professor Wistar taught that the contraction of the pupil
was produced by circular fibres, and the dilatation of it by
its elasticity.   In objection  to this, Dr. Physick remarks,
that as elasticity is as  much  a property of dead as of living
matter, in death therefore we should always find the pupil
dilated from the want of active  contraction in the  circular
fibres; also, in cases of concussion of the brain, where there
is a sudden loss of sensibility and of muscular motion, the
pupil should be invariably dilated,  but  the  fact is that the
pupil remains just in the same state that it was at the mo-
ment of the accident.
  Notwithstanding the extreme sensibility and mobility of
the iris on the  admission of  light, one is occasionally asto-
nished to find it not contracting when instruments are ap-
plied to it, as I have had an opportunity of twice observing,
upon the  removal of a considerable portion of it, in  making
an artificial pupil for opacity of the cornea.   In these cases
upon the letting out of the aqueous humour, it became quite
as flaccid  as we are accustomed to see it  in our dissections.
The  same remark has been made  by Mr. Charles  Bell.
  The Blood Vessels of the Iris are  principally branches of
the Long Ciliary, which have been alluded to. Each of the
two  Long Ciliary Arteries having  gained the greater  cir-
cumference of the iris, bifurcates; the bifurcations run along
this circumference, meet, and join with the corresponding
ones  of  the other  arterial  trunk.   From  the circle thus
formed there proceed  radiated branches, that run towards
the pupil, and form around  its margin,  by their frequent
anastomoses, a fine vascular network. The radiated branches
themselves  give off collateral  branches, which supply the
intermediate spaces of the iris.*  The Veins of the  iris are
also numerous, but cannot be quite so distinctly seen: they
enter into  the long ciliary  veins, and  also into the vasa
vorticosa.
  The Nerves of the Iris belong, in part, also to the choroid
coat, and are classed under  the  term Ciliary {Nervi Cili-
ares.) They arise from the ophthalmic ganglion, and from
* Soemmering, lcones Oculi Hum. 
THE BALL OP THE EYE.              413
the trunks contributing thereto, and  are  about  twenty in
number.  They penetrate the posterior part of the sclerotica
obliquely, and then  run forwards between it and the cho-
roides.  Having  reached the posterior part of the ciliary
ligament, they penetrate it, and distribute their filaments in
its substance,  after  the  same fashion that the trigeminus
nerve is divided in its ganglion.   This circumstance has
given occasion to Soemmering, to consider the ligament as
a true ganglion,  and to call it Annulus Gangliformis.  The
nerves then get  to the front of the iris, and are there distri-
buted as white radiating filaments, in  the course of which
may be observed small nodes, supposed by Meckel to be
Ganglions.
   The trunks of the Ciliary nerves depart from the common
form of such  bodies, by being flattened instead of cylindri-
cal:  they are  small, and  resemble sewing threads.  From
their number, the iris is probably more abundantly supplied
with nerves than any other organ  of the body.

   The Retina forms the third coat of the eye, and lines the
internal face of  the  choroides almost in  its whole extent,
The optic nerve having passed  through the sclerotica, ter-
minates on its inner side  by a bulb or button-like end, from
the circumfereuce of which the retina begins to expand, and
may be traced satisfactorily as far as the commencement of
the ciliary plaits of the  choroid coat, where it terminates by
a straight edge, somewhat thickened. Just at this edge, the
retina adheres to the vitreous humour, and is supposed, er-
roneously  by some  anatomists, as Bichat  and Monro, to be
continued  on to the circumference of the lens.   Repeated
dissections, and the substantial testimony of  Soemmering,*
have satisfied me that the retina cannot be fairly traced be-
yond the greater circumference of the impressions made on
the  vitreous humour by the ciliary striae or ridges.  When
the  eye is slightly  macerated, the retina always parts from
 the vitreous humour at this point;  moreover, when its struc-
 ture is still more  slightly  changed by freezing and then
*  Icones Oculi Humani. 
414
NERVOUS SYSTEM.
 thawing, the retina manifests a decided preference to sepa-
 rate at this line, and, under the most  careful dissection, it
 is very difficult to prevent it. In addition to these conside-
 rations,  there is a well marked  change of colour at the line
 mentioned; in front of this  line, the surface is transparent
 when cleaned  from the pigmentum nigrum, whereas, if it
 were retina, it  should  be the colour of ground glass,  as is
 usual  in  the  dead body; also* the veins of the retina never
 trespass beyond this line, but are seen  to cruise along it.
   Most anatomists teach  that the retina is an expansion of
 the optic nerve. Bichat believed that the latter terminated
 at the bulb, and that  the  retina was  another  part of the
 structure,  but still consisting of the same sort of nervous
 matter.  The latter opinion  is  probably the more strictly
 correct,  because there  is  more pulpy matter in a section of
 the retina  than can be found  in the same length of the optic
 nerve; also, if  the retina were simply  an expansion of the
 nerve, without any addition  of matter to it,  it should, from
 its hollow globular shape, be thinner in the  middle, where
 it is  most expanded, than  it is where  the  expansion  first
 begins, at the bulb of the  optic nerve.
   The retina  does not  adhere to the choroid coat, neither
 to the vitreous humour which it encloses, except at the line
 mentioned; when  this line of attachment  is broken, the
 retina quickly collapses.
   The texture of the retina is extremely soft and pulpy; in
 the living state, it  is  probably perfectly transparent, but
 this can only be conjectured from the readiness with which
 the vessels of the choroid coat can  be seen in animals des-
 titute of pigmentum  nigrum.   It is composed of two la-
minae, of which  the external is medullary, and the internal,
or that next to the vitreous humour, is  formed of a fine re-
ticulated cellular membrane  with   blood  vessels running
through it.  The external lamina may be removed  by a ca-
mel's hair pencil, or by slight putrefaction and washing, so
 as to leave the internal  entire.   The celebrated John Hun-
 ter succeeded, however, in separating the two laminae fairly
from each other and preserving them,  so as to show their 
THE BALL OF THE EYE.
415
difference.   This specimen may be considered unique, and
every  way  deservi  g of the source  from which it  pro-
ceeded. *
  Exactly in the axis of the eye, or at its centre posteriorly,
consequently about a line and a  half from the outer side of
the bulb of the optic nerve, Soemmering discovered, in 1791,
a yellow spot of a line in diameter, with a small hole in its
middle made by a deficiency of medullary matter.  From
the optic nerve there goes,  towards the  foramen, a small
fold of the retina, pointed at its internal end and obtuse or
bifurcated externally. Unless the eye be fresh, these things
cannot be seen distinctly, for the evaporation of the aque-
ous humour causes  a collapse or wrinkling of the retina,
which obscures them.   But in a perfectly fresh  eye, which
is well managed, they may be seen both from before and be-
hind.   It was thought,  for some time, that the yellow spot
and the  foramen were  peculiarly  attributes of  the human
being; more extended and successful  observation has cor-
rected  this  mistake,  by detecting them in several classes of
animals.
  In the centre of the optic nerve, where it enters the eye,
is a foramen for the  passage of the artery and vein belong-
ing to  the retina.  These vessels ramify, by a few branches,
on the internal surface of the membrane, and form a sort of
circle surrounding the yellow spot.  Neither  the branches
of arteries or veins communicate with those of the choroides.
and, as observed, never go beyond what we just  considered
as the anterior margin of the retina, but rather run along it,

  Interposed between the retina  and  the choroides, is  a
most delicate serous membrane lately discovered  by Mr. Ja-
cobs,  Demonstrator  of Anatomy in  Trinity College, Dub-
lin.   By preparing  the retina in  the  usual way, and  then
floating the  eye in a saucer of water, this  membrane  may
be turned down with the ha tdle of a  knife from the optic
nerve to  the termination of the  retiaa.  It is supposed to

  * The fact was communicated to me by Dr. Physick, who studied under
Mi-. Hunter, and frequently saw the preparation. 
416
NERVOUS SYSTEM-
be  the  seat of the  ossifications which are  sometimes met
with in the eye.


               Humours of the Eyeball.

  The Vitreous Humour (Humor  Vitreus,  Corpus  Vi-
treum) occupies, with the exception of a  very small part
just behind the iris, the whole of the space posterior to the
latter.   It is  therefore very  nearly globular;  is in contact
the greater part of  its extent with the retina, at least as far
as the latter membrane proceeds; in front  it is in contact
with the crystalline humour, and from the margin of the re-
tina to the circumference of the lens it is in  contact with the
ciliary body,  meaning thereby  the  ciliary striae and pro-
cesses of the choroides.
  Two parts compose the  vitreous  humour,—the hyaloid
membrane and a thin fluid.   In a natural state they are per-
fectly transparent, and therefore  cannot be readily distin-
guished from  each other;  but by immersion  in  spirits of
wine the  membranous portion is brought to the  colour of
ground glass, and may then be studied  very advantageous-
ly.   The  membrane, though  extremely delicate, is gene-
rally strong enough to permit  the whole  vitreous body
to be suspended in the air by a thread passed through it,
and it may also  be momentarily held  up  with  a pair of
forceps.
  The Tunica Hyaloidea may be traced as  a complete cap-
sule, forming  the  periphery of the  vitreous humour;  and
from the internal face of this capsule there proceeds a great
number of partitions dividing  the whole cavity into cells of
various magnitudes and forms. Some anatomists,  who have
frozen the eye and  then picked out the pieces of ice from
the cells, have got the  idea of their being all cuneiform, and
of their edges pointing forwards.   Our preparations in the
anatomical cabinet  are  perfectly satisfactory in exhibiting
the existence of an arrangement of cells, but do not mani-
fest a regular cuneiform shape in them.
  When the capsule of the tunica hyaloidea has got to the 
THE BALL OF THE EYE.
417
distance of two lines or thereabouts, from the circumference
of the lens,  it divides into two  laminae, which  reunite at
the circumference of the  lens.    They  then  divide again,
and one goes before the capsule of the  lens,  and the other
behind it.   The space  between the two layers, around the
circumference of the lens, is the canal of Petit, and is that
part of the tunica hyaloidea which is impressed by the cilia-
ry striae  and ridges of the choroides.   At intervals, pass-
ing in a radiated manner, from the exterior to the interior
circumference of the canal,  there  is a sort of shortening or
constriction of it, producing partial septa in its cavity; so
that when the canal is inflated, it seems  to consist of a  series
of  small cells, arranged circularly.  The cells of the colon
will give some  idea of this arrangement, though they are
produced in an  entirely  different manner.
   The fluid part of the vitreous humour, by analysis, gives
out 98.40 water, .16 albumen,  and the  remainder is saline.
In  consequence of the very small quantity of albumen in
it,  neither acids or heat coagulate it to a striking degree.
   The vitreous  humour  is supplied with a branch from the
central artery of the retina.  This branch  does  not convey
 red blood,  but   only serum, except in the foetal eye.    It
 may be injected, at almost any age,  with  size, coloured
 with vermilion; but is then, of course, put very much  on
 the stretch.  It has been well  described by Zinn.   It pe-
 netrates the vitreous humour  near the optic nerve,  and is
 disseminated by very fine branches on the periphery,  and
 on  the  internal cellular structure of the tunica hyaloidea.
 M. J. Cloquet has described particularly one branch, which,
 running through the centre of the vitreous  humour, in an
 appropriate canal, is spent by small ramifications upon the
 posterior part of the capsule of the lens.
    Some anatomists*  speak of a fluid  between  the  tunica
 hyaloidea and the retina: when it does exist, it in all pro-
 bability  is the fluid  of the  vitreous  humour,  which has
 strained through the tunica hyaloidea after death.

                   * Bichat, Anat. Descrip.
    Vol. II—53 
418
NERVOUS SYSTEM.
  The Lens (Lens Crystallina) or  the  Crystalline Hu-
mour,  as it is very generally called, is placed immediately
behind the pupil, in a depression on the front of the vitre-
ous humour.   Its shape is that of a doubly convex lens, of
which the  posterior convexity is greatest, being the section
of a sphere whose diameter is from four to five lines, while
the anterior convexity is in the  proportion of a sphere of
from  six to nine lines.   The usual breadth of the lens is
about three  and a half lines.  It varies  its shape in a re-
markable degree at the different periods of life; immediate-
ly after birth it is spheroidal, in about six years afterwards
its lenticular shape is well marked, and subsequently it be-
comes more flat and thin.
  The Lens naturally  is  perfectly transparent.    In  the
greater part of its  thickness it has  the consistence of half
dissolved  glue, but  its centre  is much more solid; this
change, however, is effected successively.   When it is sub-
jected to the mineral acids, to heat, to alcohol, and several
other agents, it becomes much more  solid throughout; it
may then be separated, like an onion, into a series of con-
centric lamellae, subdivisible into longitudinal  fibres.  Be-
sides these there are fibres more or less oblique which hold
the lamellae  together.   These arrangements  prevail from
the centre to the circumference of the lens;  and  between
its  laminae there  is a diaphanous humour resembling that
between it and its capsule.*
  The Lens is  invested by a capsule which  is a complete
sac, having  exactly its  shape, but separated  from  it, to a
very inconsiderable extent, by the transparent humour just
alluded to, called  the  Liquor Morgagni.  The capsule is
covered in front by a layer  of the tunica hyaloidea adhering
very closely to it, but which, in one instance, I was enabled
to peel off partially in the eye of a sheep, from one side to
the other.   The capsule is  covered, in like manner, on its
posterior face,  by the tunica hyaloidea, but the two may be
separated there more easily, according to the observations
of  Bichat.   Some of the  most distinguished  continental
* J. F. Meckel. 
THE BALL OF THE EYE.             419
 anatomists  are  decidedly in favour of the capsule  of the
 crystalline  being a complete bag; but it is rather unsettled
 whether the exterior margin of the capsule bounds the les-
 ser circumference of the canal1 of Petit,  or whether the two
 layers of the tunica hyaloidea  unite previously at the cir-
 cumference of the capsule.   The latter  seems to be the opi-
 nion of M. J.  Cloquet.   Dr. Physick, in some  cases  of
 membranous cataract,  has succeeded in  drawing out the cap-
 sule entire,  so as to exhibit its whole extent when it is float-
 ed in water.
   The capsule in front of the lens is much thicker than the
 tunica hyaloidea,  and  its difference of character from the
 latter appears to me to be very strongly marked.  For not-
 withstanding its immersion in spirits of wine, it retains its
 transparency; it is hard and elastic,  and when clipped with
 the  scissors, gives  nearly  the same sensation as the  thin
 paring of a finger nail would;  or, as has been observed by
 Haller, it, in this respect, resembles the cornea.   The ana-
 logy with the cornea ceases, however, at this point; for the
 cornea has always so much  albuminous  matter in  it as to be
 rendered turbid when  it is immersed in alcohol.   The pos-
 terior section of the capsule  of the lens, is not so well marked
 either  by its thickness or specific characters as the anterior,
 yet our preparations in the  University demonstrate its ex^
 istence equally as conclusively.   It  is  more assimilated to
 the nature of the tunica hyaloidea.
   In the injected foetal eye, the artery of the tunica hya-
 loidea  which comes  from the central one of the retina, is
 seen to furnish several  minute ramifications to the posterior
 face of the lenticular capsule; some  of its branches also go
 to the front of the capsule,  but the  latter part is furnished
principally by arterioles from the  ciliary body of the cho-
roides.   The two sets of  arteries  anastomose with  each
other, some of the latter are also spent upon the membrana
pupillaris.
  The  point is yet doubtful whether any of these arteries
penetrate  into the body itself  of the crystalline humour.
Ruysch, Albinus, and Haller, assert  the fact of their having 
120
NERVOUS SYSTEM.
seen and injected them  in  the  human species and in ani-
mals, and J. F. Meckel admits their testimony.  Yet there
are not many anatomists who can  corroborate it  by their
personal observations.  It is sufficiently reasonable to admit
it, for without, we cannot conveniently  account  for the
growth and nutrition of the lens,  as  well as the  morbid
changes which occur in it.   It should  be  observed that if
this  vascular connexion  does  exist it  is a  very weak one;
for the lens seems  to  be simply surrounded by  its capsule
without adhering to it.
   Some veins which discharge into the veins of the choroid
coat have  been  observed by Walter* on the posterior part
of the capsule.   It should be  continually borne  in  mind
that neither the arteries nor veins of the healthy crystalline,
nor of its capsule convey red  blood; in which respect they
correspond with the hyaloidea, for if this were the case, vi-
sion would be very much disordered by it. It may be that
the moats  or  specks  seen in  ophthalmia arise  from  the
grosser particles of the blood,  getting into these serous ves-
sels by the dilatation of the latter.
   The Lens and its Capsule are devoid of nerves, at least
none have been as  yet traced  into them.

   The Aqueous Humour (Humor Aquosus) occupies the
space which is between  the anterior face of the crystalline
capsule, and the posterior face of the  cornea.  This space
is unequally  divided  by the iris  into  two  chambers, of
which the  anterior is  in front of the latter membrane,  and
the posterior behind it.  In consequence of the convexity
of the lens, the  posterior chamber has  but  very little depth
just behind the pupil;  but its space is augmented at the cir-
cumference of the  crystalline, so as to  leave room for the
floating of the ciliary  processes and for the motions of the
iris.  The posterior chamber is therefore a circular vacuity;
the centre of  which,  from  the  projection of the centre of
 the crystalline,  has scarcely  any appreciable depth.  The
 anterior chamber in its shape  resembles  the segment of a
' * De Oculis.  Berlin, 1778. 
THE BALL OF THE EYE.
421
sphere: its depth  depends essentially on the size  and the
projection of the  cornea.
  The aqueous humour is perfectly transparent, and almost
as fluid as water.  The analysis of Berzelius  exhibits 98
parts of water, 1  of hydrochlorate and lactate of lime, .75
of some animal matter soluble in water, and a very small
quantity of albumen.   From the latter circumstance it will
be understood how this fluid refuses to coagulate on the ad-
dition  of alcohol  or of mineral acids to it, and is only ren-
dered  in a very slight degree turbid by them.  The rapidi-
ty of the exhalation of this  fluid is remarkable: when the
whole of it is lost in the operation for cataract, it is regene-
rated in from twenty-four to thirty-six hours.   Its source
has  been sought  for in suppositious  canals and glands, but
the  more probable opinion  is, that it may come  from any
or all  of the exhalent arteries of the chambers of the eye.
   Like the other two humours of the Eye, the aqueous is
furnished with a capsule, but whether it is complete or not
is yet  undetermined.  By immersing the eye in hot water,
or in alcohol,  this capsule  may be readily detected on the
 posterior face  of the cornea, and to the greater  circumfe-
 rence of  the iris;  it may even be  traced for some distance
 on  the front  surface of the  latter.  Some  of the French
 anatomists, as Demours,* Descemet, and J. Cloquet, have
 asserted that it continued also through the pupil to line  the
 posterior chamber. An opinion like this, from the extreme
 tenuity of the parts, must  be rather the result of conjec-
 ture than of accurate observation; it has  therefore never
 found  its way with full force  into the writings of anato-
 mists.  The condition of the pigmentum nigrum on  the
 posterior face  of the iris,  and on the ciliary processes, would
 seem  to be an objection to the existence of this  capsule in
 the posterior chamber of the eye.  But  if it really does ex-
 ist  there, as is pretended by M. Portal, who supposes it to
 be derived from  the tunica hyaloidea, its structure is incom-
 parably more  delicate than  that part on the cornea, and in-
  deed  is merely glutinous.

                   * Demours, Lettre, 1767. 
422                 NERVOUS SYSTEM.
    The  Chambers of the Eye,  till the seventh  month  of
 foetal existence, and sometimes later, are perfectly separated
 from each other by the Membrana Pupillaris, called so from
 its position in the pupil of the iris.   It was discovered  in
 1740, by Wachendorf,  and is  sometimes  called after his
 name.  It is a thin, delicate, and transparent membrane,
 which is stretched across the pupil from its circular margin,
 and  may, by its  colour be  readily distinguished from the
 iris,  when it has  been made somewhat turbid by alcohol.
    The Membrana Pupillaris consists, according to M. J.
 Cloquet,* of two laminae placed back to back, of which the
 foremost is a continuation of the membrane which lines the
 anterior, chamber of the eye, and the hindmost, of that which
 lines the posterior chamber.  According to this, it may be
 noticed that each chamber  has its distinct capsule.   This
 membrane is very vascular; some of its arteries are those
 which subsequently form the internal arterial circle of the
 iris, and they radiate from the circumference to the centre
 of the membrane;  others come directly from the long ci-
 liary  arteries, and others again from the arteries of the crys-
 talline capsule.  These several vessels are found principally
 on its posterior face.   Its veins have not been observed.
   This membrane first shows itself about the third  month
 of foetal existence, and is most perfect at the seventh; from
 the latter period it begins to decline,  by disappearing from
 the centre to the  circumference.   At  the  ninth month it
 consists  only in a few  loose  flocculent  masses adhering to
 the pupil.  M.  J.  Cloquet has ascertained that its vessels do
 not participate in its destruction, but that the arches which
 they form are retracted to the margin of the pupil, and there
 form the lesser arterial  circle of the iris.  From the obser-
vations of  Drs. Jacob and Tiedemann, it appears that traces
of the membrana pupillaris exist for ten  or fifteen days after
birth.  The latter, in one case, injected its vessels in a foetus
at full term, t

  * Journal Universelle des Sc. Med. Par. 1818.  Mem. sur la memb. pu-
pill, Paris, 1818.
  f Am. Med. Jour. vol. i. p. 192. 
THE EXTERNAL EAR.
                    CHAPTER II.

                     OF THE EAR.

  The ear, the organ of hearing, is placed principally with-
in the petrous portion of the temporal  bone, and consists in
the External Ear, the Tympanum, and the Labyrinth.


            SECT. I.—OF THE EXTERNAL EAR.

  The position of this portion of the organ  is familiar to
every one.  It  is useful in collecting the rays of sound, and
in conveying them to the more internal parts.  It is formed
by the structure,  exterior  to the petrous bone, called, in
common language, the Ear; and by a canal which leads in-
ternally to the tympanum.  The basis of this portion is car-
tilaginous, on which  circumstance it  depends for the per-
manency of  its  shape.
  The ear,  of  common  language, is divided  into two por-
tions, Pinna* and Lobus: the former is the most extensive,
as it comprehends all the cartilaginous portion; the latter is
attached to the inferior margin of the former, and,  having
no cartilage  in  its composition, is soft and pendulous.
  In the centre of the external ear is a deep depression called
the Concha; in the  bottom of it  is the orifice of the canal
leadi ig to the  tympanum,  and called Meatus Auditorius
Externus.  The circumference of the pinna is convoluted
into a scroll  called the Helix, and commences just above the
meatus by a ridge.  This ridge divides the concha into two
unequal  cavities,  of  which  the lower is the larger.  The
scroll becomes  gradually less prominent,  till it terminates
at the posterior inferior part of the pinna, in the lobus.
  The Antihelix is  the  slightly  curved  and vertical  emi-
nence in the middle  of the pinna; its lower part forms the
From some resemblance to a certain shell fish. 
424
NERVOUS SYSTEM.
posterior boundary of the concha, and its upper part bifur-
cates  into two small ridges, between which there is a de-
pression called the Scapha.  Between the antihelix and the
posterior half of the helix, is an oblong depression called the
Fossa Innominata.
  The Tragus is a cartilaginous elevation of the pinna placed
in front of the concha, and inclining somewhat over it; op-
posite to it, at the inferior part of the concha, is the Anti-
tragus Cartilage.
  The cartilage upon which the external ear depends for its
shape is of a  thickness very nearly  uniform, of course the
ridges and depressions  on its exterior surface have corre-
sponding depressions  and ridges on the side next to the
head.   It  is interrupted  at  several places by fissures; for
example,  there is one  of considerable  size filled up  with
ligamentous  matter, which separates the upper margin  of
the tragus from the beginning of the helix; there is another
between the lower extremity of the antihelix and the anti-
tragus.   In the tragus, there are  two and sometimes three
small narrow ones, said, by Santorini, to be filled with  mus-
cular fibres; but the latter assertion does not correspond
with the observations of subsequent anatomists, as the mat-
ter appears fibrous.
   The externa^ ear is united to the side of the head by three
ligaments.   The  anterior arises from the root of the zygo-
matic process above the articulation of the lower jaw, and
is inserted into the pointed  production of cartilage on the
fore part of  the helix.  The posterior arises from the swell
of the temporal bone, which runs into the front margin of
the base of the mastoid process, and is inserted into the con-
vex side of the concha, at the beginning of the meatus audi-
torius.  The superior arises from the temporal aponeurosis,
and is inserted into the upper  part of  the concha.  These
ligaments lie immediately below the muscles destined to
 move the ear.

   The Meatus Auditorius Externus is, in the adult, an inch
 in length, reckoning from  its external orifice to the mem- 
                  THE EXTERNAL EAR.       ^       *i25

brane of the tympanum, which closes it inwardly.  It is
about three lines in diameter, is rather oval than cylindrical,
and somewhat smaller in the middle than at either of its
extremities.  It runs inwards, with a slight inclination for-
wards; the exterior half is  formed by the cartilage of the
pinna, and the internal half by the temporal bone; it departs
from  the  horizontal course, in being curved at its middle
where the two  sections join.  This curvature has its con-
vexity upwards, so that when we  wish  to look  to the bot-
tom of the canal, the external ear must be pulled upwards
and backwards.
   The cartilaginous portion of the  meatus  auditorius is
formed by a triangular piece, springing from the base of the
tragus and from the inferior anterior part of the concha.
This  portion is nearly a tube, but is interrupted above and
behind  by the intervention of a dense  fibrous tissue, con-
tinuous with, and indeed the same with that which joins
the helix and the tragus.  The cerebral margiiydf the car-
tilaginous meatus forms a point below, and adheres by liga-
ment very closely to the asperities  on  the margin of  the
bony meatus.  If there were no fissures in the external ear,
it would, therefore, be almost immoveable.

   The skin covering the external ear, is more delicate than
in most other parts of the surface  of the body.  Its sebace-
ous glands or follicles  are very abundant, and in infants se-
crete freely their peculiar fluid. When a slight inflammation
occurs, this  discharge is frequently purulent without ero-
sion.   A duplication of  the skin, containing a delicate gra-
nulated adeps with some fibrous matter, constitutes the lobe
of the ear.
   The skin,  after lining the concha, descends into the mea-
tus auditorius and lines  it also, as well as the external face
of the membrane of the tympanum.  It adheres moderately
to the cartilaginous part of the tube, and more tenaciously
to its fibrous portions; between it and the latter, are found
 many small  reddish bodies, generally  oval, the Glandulae
    Vol. II.—54 
126                NERVOUS SYSTEM.
Ceruminosae,* from which proceeds the earwax.  The skin
is extremely thin in the bony meatus, adheres closely to its
periosteum, and is highly sensible; where it forms the ex-
terior layer of the mem brine of the tympanum,  it may be
detached from the latter with the slightest force, and seems
to be converted  almost entirely into cuticle.   A slight ma-
ceration  or incipient  putrefaction frequently enables one
to draw the cuticle out entire  from the meatus, so that it
looks in shape like the finger of a small glove.
  The dermoid  lining of the meatus is studded with fine
hairs, which serve to keep  out small  bodies that may be
floating in  the air.  A considerable number of small  pores
are also seen in it, which are the orifices of the ducts of the
ceruminous glands.  The discharge of the latter, when first
secreted, is thin and white: by evaporation it becomes thick
and yellow, and by accumulating obstructs the passage.

  There are several small  muscles situated on the external
ear, which are for the most part so feebly developed that
they cannot always be found, and when they do exist they
seem more  like the  rudiments of what  is well marked  in
animals, than intended for a special purpose in the human
body.

   1.  The Helicis Major is an oblong fasciculus, situated on
the front of the  helix.  By its lower end it is attached to the
point of cartilage on the front of the helix, and its other ex-
tremity extends to the top of the latter.

   2.  The Helicis Minor is a  small square fasciculus, also on
the front of the helix, between the folded margin of the lat-
ter and the inferior half of the helicis major.

   3.  The Tragicus is a square fasciculus, on  the front sur-
face of the  tragus, near its margin: its upper extremity some-
times runs into the helicis major.

   4.  The  Antitragicus is  a  small oblong fasciculus,  which
* Duverney, C£uvres Anotomiques. 
THE TYMPANUM.
427
arises from the upper extremity of the antitragus, and going
upwards it is inserted into the inferior extremity of the anti-
helix.

  5. The Transversus Auriculae is on the cerebral surface
of the pinna.   It arises  from the prominence of the con-
cha, and is inserted into the hollow dorsum of the anti-
helix.

  There are some other muscles which  may be uniformly
found  and are intended  to move the external ear upon the
side of the head,  though from  the  want of exercise there
are very few individuals capable of making them contract.
They are

   1.  The Attollens Auriculae is placed  on the side of the
head beneath the integuments: it is a broad, thin,  and some-
what triangular muscie, which arises from the inferior mar-
gin of the  tendon of the occipito-frontalis, and  from the
temporal aponeurosis.    It becomes narrower in its descent,
and is  inserted  tendinous into the elevation of the  pinna,
corresponding with the scapha.
   Its name implies its action to  be that of raising  the pinna.

   2.  The Retrahens Auriculae, consists in two or three ob-
long fasciculi, placed parallel, and one above the other.   It
arises from the mastoid portion of the temporal bone, above
the mastoid process, and is inserted tendinous into the con-
vex side of the concha near the  meatus auditorius.
   It draws the pinna backwards.

   3.  The Anterior Auriculae is a small quadrangular slip,
just  above the root of  the zygomatic process.   It arises
from the temporal fascia, and is  inserted  tendinous into the
fore part of the helix just above its root.
   It draws the pinna forwards and upwards. 
u?
NERVOUS SYSTEM.
              SECT. II.--OF THE TYMPANUM.

   The  Tympanum  is the middle  portion of the organ of
 hearing, being interposed between the meatus  auditorius
 and the labyrinth.   Its depth is about three lines, its ante-
 roposterior diameter about six, and  its vertical  diameter
 rather more, though from the general inequality of the ca-
 vity, and its communication with adjoining cavities it is not
 easy to fix upon Very precise measurements.

   The  Membrana Tympani, is a complete membranous
 septum, interposed  between the meatus  externus and the
 tympanum.  It is placed very obliquely, so that its upper
 edge inclines outwards, and its under edge inwards; the lat-
 ter therefore forms a very acute entering angle with the in-
 ferior part or floor of the meatus, and gives to that portion
 of the meatus an  additional length, which renders it diffi-
 cult to see  to  its bottom.  The membrane of the tympa-
 num is  nearly circular,  and has its  circumference adhering
 very closely to the  external orifice of the tympanum.  It
 is slightly tense, and has its middle drawn inwards by being
 attached to the handle of the malleus.
   The membrana  tympani consists  of four laminae; the two
 exterior of which being the cuticle and the cutis vera,
 which line  the meatus auditorius,  are  easily detached, as
 mentioned before, and seem scarcely to adhere to the layer
 below.   The third layer  is the proper  membrane,  and is
 distinguished by its  dryness and by its transparency.  Sir
 Everard Home was enabled to detect radiated  muscular
 fibres,  forming it in  the elephant*   In the human subject
its fibrous character is best seen on its internal face, but the
radiated arrangement is not so distinct.   Caldani  considers
it as formed by filaments,  decussating each  other at right
angles, and intermixed with blood vessels.t  The internal
layer is a continuation of the lining membrane of the tym-

  * Philosophical Transactions, for 1800.  London.
  t Plate XCV1II. Anat. 
THE TYMPANUM.
429
panum; it is separated with some difficulty, owing to its te-
nuity.
   The proper membrane of the tympanum, when success-
fully injected, exhibits a high degree of vascularity* though
in its natural state but very few red blood vessels are seen
in it.

   The floor of the tympanum, or the side next to the laby-
rinth, presents an  unequal surface.   In its middle is a well
marked rising, the Promontory,  (Promontorium) formed
by one end of the  labyrinth.  Just above the superior mar-
gin of this prominence, near its centre, is an oval opening,
called from its shape, Foramen Ovale,  or Fenestra Ovalis;
having its long  diameter horizontal,  its superior  margin
rounded or concave, and  its inferior straight.  At the pos-
terior inferior part of the promontory  is another opening,
which though somewhat  triangular, is  called the Foramen
Rotundum,  or Fenestra  Rotunda,  and  in the  dried bone
leads to the  cochlea, but is naturally stopped by the lining
membrane of the tympanum.  According to M.  Ribes, this
membranous plug has also two other layers, an internal one,
the continuation of what lines  the cochlea, and a middle
one, which is peculiar.  In these respects there is a corres-
pondence with the membrana tympani.

   The Eminentia  Pyramidalis is a small conical eminence
projecting from the posterior part  of the tympanum,  on a
line with the fenestra ovalis.  It is hollow, contains a mus-
cle, and communicates at  the other end with the Canal of
Fallopius.   Lower down and more externally,  there is a
small orifice, (Apertura Chordae) through which the nerve
called Chorda Tympani passes.

  The Mastoid Portion of the Temporal bone, in the adult,
abounds in large cells or sinuses, which communicate freely
with one another.  They are distinct from the diploic struc-
ture of the bone, as they  contain  no meditullium, and are

  * Ruyschii, Epist. Anat. Probl. viii.  Anatomical Museum of Unhrv 
430
NERVOUS SYSTEM.
lined  by a continuation  of the internal  membrane of the
tympanum,  which is extremely thin upon them.  The ori-
fice of communication between these cells and the tympa-
num is placed at the superior posterior part of the latter; it
is rough and irregular, and partially occupied by the short
leg of the incus.   Just in front of this opening, the cavity
of the tympanum is extended vertically,  for the purpose of
accommodating  the body of the malleus and of the incus,
whereby they are in  a great  degree concealed,  unless the
corresponding margin of the tympanum be cut away.

  At the fore part of the  tympanum is the Eustachian Tube,
which runs for six or eight lines in the substance of the pe-
trous bone,  near its exterior margin, and then terminates in
a cartilaginous and membranous portion, which communi-
cates  with the pharynx at the posterior  nares.   The latter
extremity of the Eustachian Tube is placed on a line with
the posterior end of the inferior spongy bone.   Its orifice is
rounded or oval,  is large enough to admit the tip of the lit-
tle finger, and reposes against the side of the internal ptery-
goid process of the sphenoid bone.   Though almost within
the precincts of the posterior naris, this orifice is to be con-
sidered as opening into the pharynx.
  This  canal, in  its  whole length, measures  nearly  two
inches, and,  with the exception of the  portion in the pe-
trous bone,  is cartilaginous  and membranous.   The carti-
lage is a single, thick, triangular  plate,  flat,  and adhering
by one of its  edges to the pterygoid process.  The under
part of the  tube  is membranous,  thin, and  affords attach-
ment to some of  the muscles of the soft palate.  Its course
is nearly horizontal, backwards and outwards.
  It  is  lined  in  its whole extent, by a very fine mucous
membrane continuous with that of the pharynx and of the
tympanum.   This membrane is thickened at its anterior ex-
tremity by the mucous glands beneath it, which  assist in
giving the marked elevation to  its orifice.   The canal di-
minishes as  it goes backwards,  so  as to  receive with diffi-
culty a small probe. 
THE TYMPANUM.
431
  Parallel with the bony part of this canal, but above it
and separated by a very thin  partition of bone, is another
canal which lodges a muscle of the malleus.   On the outer
side of the eustachian tube is the glenoid foramen, by which,
in the dried bone, the  tympanum communicates with the
glenoid cavity; in the recent state, the foramen receives the
long process of the malleus and its  muscle, and transmits
the chorda tympani.

  There are four bones in the tympanum, which, being suc-
cessively articulated with each other, form a chain, one end
of which is fastened to the  membrana tympani, and the
other end rests upon the  foramen  ovale.  They are the
 Malleus; the Incus;  the Orbiculare; and the Stapes.

   The Malleus forms the fore part of the chain,  and  is
placed  almost vertically. Its superior extremity is the head,
 which  is rounded, with the exception of the posterior face,
 where  a small concavo-convex surface is observable,  for the
 articulation with the  incus.  Its lower extremity is long
 and tapering, inclines inwardly, terminates by a little knob,
 and forms an angle with the part above; this portion is the
 manubrium, and adheres its whole length to the membrana
 tympani, commencing at the superior margin of the latter,
 and insinuating itself between the  internal and  the proper
 layer,  as far as the centre  of  the membrane.   It is this ad-
 hesion with the inclination inwards of the manubrium, that
 causes the  membrane to be depressed  in its ce itre.
   Between the head and the manubrium is a short portion
  called  the neck.  From the  superior external extremity of
  the manubrium there proceeds outwardly the short process
  (Processus Brevis;) and from the front of the neck, there
  proceeds the long and very delicate process, concave  ex-
  ternally and  convex internally, which  is insinuated  into
  the glenoid foramen, and is  the Processus Longus or Gra-
  cilis.

    The Incus is behind the malleus, and  is also upright.  It
  consists in a body and two branches, which  diverge verv 
432
NERVOUS SYSTEM.
 considerably,  and has a  general resemblance to a molar
 tooth.  The body presents on its fore part a deep concavity,
 which articulates with the convex head of the malleus.  The
 branch which arises from the back  part of the body is ho-
 rizontal,  looks into the orifice of the mastoid cells, and is
 much shorter than the other.   The  inferior branch is long,
 upright, tapering, and nearly parallel with the manubrium
 of the malleus, but somewhat within it.

   The  Orbiculare is a very small flattened sphere of bone,
 which articulates with the lower end of the long process of
 the incus, and in adult life as most  generally fused into it,
 so as to lose its distinctive character: the latter change some-
 times occurs even in early infancy.

   The Stapes is the last of the chain.  It resembles very
 strongly the common  stirrup iron, from whence, its name,
 and is placed horizontally at right angles to the incus, being
 separated from the extremity of the long process of the lat-
 ter by the os orbiculare, and being directed inwards to the
 foramen ovale.   It is composed of a head, two crura, and
a base.
   The head is oblong and  flattened:  it has a slight depres-
 sion where it joins the orbiculare.   The crura are slightly
 curved, with the concavities towards each other;  the ante-
 rior is somewhat straighter than the posterior, and is also
 shorter.   They are both excavated longitudinally  on their
 concave surfaces, and between them is stretched a process
of the lining  membrane of the  tympanum.  The base is
precisely adapted to the fenestra ovalis, and is connected to
it  by  the  lining  membrane of the tympanum, but not so
closely as  to  prevent  it from  executing  slight vibratory
movements.
  Between the malleus and the incus there is a moveable
 articulation with  a synovial membrane, but the other joints
of the chain are simply ligamentous.

  This chain of bones is moved by several muscles, which 
                     THE TYMPANUM.               '*<*'*

thereby influence the degree of tension of the membrana
tympani.

  1. The" Laxator Tympani arises from the posterior end
of the spinous process of the sphenoid  bone, and passing be-
hind the articulation of the lower jaw into the glenoid fo-
ramen, is inserted tendinous along the processus gracilis ot
the malleus.
  It draws the malleus forwards and outwards,  so as to re-
lax the membrana tympani.

  2. The Tensor Tympani is placed in the canal just above
the Eustachian Tube.   It arises from the posterior extre-
mity of the cartilaginous portion of the latter, and having
got  into the  tympanum, is changed into a  small tendon,
which, going outwardly, is inserted into the  neck of the
malleus, just below its processus gracilis.
  It draws the malleus inwardly, consequently makes tense
the membrana tympani, and drives the  stapes into the fenes-
tra ovalis.

  3. The Stapedius aVises from the  bottom of the cavity in
the pyramid, and terminates in a small round tendon, which,
going through the apex of the latter, is inserted into the head
of the stapes.
  It draws the stapes backwards, and perhaps fixes it more
firmly by its contractions.

  4. There is a fourth muscle  mentioned  by  anatomists,
the existence of which is more equivocal; it is called the
Laxator Tympani Minor.  It arises  from the superior mar-
gin of the orifice of the tympanum, and is inserted into the
processus brevis  of the Malleus.   It is by some considered
only as a ligament, to which opinion I  am inclined.

     Of the Lining Membrane of the Tympanum.

  This membrane is a continuation of the lining membrane
of the pharynx, being introduced into the tympanum through
  Vol. II. — 55 
tJ4
NERVOO SYSTEM.
the Eustachian Tube.   It covers completely the surface of
the tympanum, and is reflected over its little bones so as to
give them a covering also: in addition  to which, it  lines
such of the mastoid cells as  communicate with  the tym-
panum.
  This membrane is extremely delicate; on its surface, adja-
cent to the bones, it is somewhat fibrous, and thereby resem-
bles periosteum; but the other surface has the characters of
the mucous membranes generally, in the nature of its secre-
tion, and in its vascularity, which is very strongly marked
in inflammations, and by fine  injections.    Bichat mentions,
that in  certain catarrhal affections its mucous secretion is
so abundant as to fill the whole  cavity of the tympanum,
and that without  ulceration.   Sometimes  in such cases the
membrane of the tympanum  is ruptured, and the  discharge
finds its way out  through the meatus externus, presenting
itself under a purulent form, as if an abscess had formed in
the ear.


            SECT. III.—OF THE  LABYRINTH."

  The Labyrinth (Labyrinthus) is placed on the inner side
of the tympanum, in the  thickness of the petrous bone.
Its  exterior parietes are  bone, but internally there is a mem-
branous structure, having, in many respects, the same shape.
It is got at with great difficulty  in the adult, owing to the
compactness of the petrous bone which  envelops it, but in
the foetus of the full period, where it is almost as large as
in the adult, the surrounding  bone is of a softer and more
spongy texture, and may be pared  away  with a  pen-knife
without much trouble.   In the latter  case, the parietes of
the bony labyrinth are about the thickness of an egg-shell,
and have  very much the same  degree  of consistency and
strength.
  The bony labyrinth consists of three  portions: the Ves-
tibulum, the Semicircular Canals, and the Cochlea.
* Antonio Scarpa, Disquisit. de auditu et olfactn. 
THE LABYRINTH.
435
  The  Vestibulum  is the cavity to  which .the  foramen
ovale leads; it, with the cochlea,, occasions the protuberance
into  the tympanum,  known as the promontory.   It is an
irregular rounded excavation,  the  surface of  which is im-
pressed by its contents; thus, at its superior, posterior, and
external part, next to the semicircular canals, there is  a su-
perficial Fossa, called, from its shape, Semi-Elliptica, and
at its anterior and inferior part, nearer the cochlea, another,
called Fossa Hemi-spherica.   These fossae are marked off
from each other by a ridge of bone,  at the  lower  end of
which there is third fossa, between the other two,  called,
by Soemmering, Cavitas Sulciformis.
  There are seven orifices besides  the  foramen ovale;  five
at its posterior part leading into the semicircular canals; one
anteriorly leading into  the  upper scala of the cochlea:  and
the last placed in its internal parietes is the aqueduct of the
vestibule.   In addition to these orifices, the parietes of this
cavity are cribriform  in the fossa semi-ellipticaand near the
foramen rotundum.*

  The Semicircular Canals (Canales Semicirculares) are at
the  posterior extremity of the  vestibulum.  They are three
in number, and  are  named, from  their relative situation,
Superior or Anterior, Posterior or Inferior, and External.
Each one forms rather more than the half of a semicircle,
and  has its cavity about half a line in  diameter: their ori-
fices are somewhat dilated beyond this measurement.   The
apparent thickness of their parietes is greater in the  adult
than in the infant.
   The Superior Canal runs  from without inwards and back-
wards.  Its anterior orifice  is above the fenestra ovalis, and
is enlarged into an ampulla or elliptical cavity. At its pos-
terior extremity, it joins the upper extremity of the inferior
canal, so that a common trunk is thus formed, the orifice of
which  is at the internal posterior part of the vestibulum,
and is dilated into the shape of a funnel, t
   The Posterior or Inferior Canal is nearly vertical; has its
v Ant. Scarpa, loc, cit.
f Scarpa, loc. ci+. 
■166
NERVOUS SYSTEM.
concavity in front and its convexity behind, and joins, as
just remarked, with the superior: its inferior orifice, which
is near the foramen rotundum, is also enlarged into an am-
pulla or elliptical cavity.   It is the longest of the  three
canals, and has its branches nearer together.
   The External  Canal is  nearly horizontal, rnd is placed
in the space left by the divergence of the other two.   It is
the shortest and the largest of the three.  Its exterior orifice
is also enlarged into an ampulla or elliptical cavity, and is
just behind the foramen ovale, or below the ampulla of the
upper canal; the internal orifice is below the common open-
ing of the other two canals.
   It is the union of the superior and of the posterior canals
at one of their extremities, which reduces  the number of
openings into the vestibulum, from the semicircular canals,
to five instead of six.

   The Cochlea forms the fore part of the labyrinth, and re-
sembles very strongly  the shell of the  common snail.  Its
base is the bottom of the meatus auditorius internus, and its
apex is directed towards the cavity of the tympanum, so that
the axis of the cochlea is turned downwards and outwards.
It consists in a conoidal tube wound spirally twice and a half
around a column of bone termed the Modiolus.  The tube
then of course, diminishes in size from the base to the apex
of the cochlea.
   This conical tube is divided in its length by a plate called
Lamina Spiralis.   Of  the two compartments  thus formed,
one is above the other. The  inferior is the larger, and com-
municates at its base, through the  foramen rotundum, with
the tympanum; it is therefore called Scala Tympani.   The
other compartment communicates at its base  with the ves-
tibulum, and is therefore called Scala Vestibuli.
   The Modiolus is of  a conical shape  and  cribriform: one
canal, larger than the others, runs from its  base to its sum-
mit.  This canal is surrounded by many others, which dimi-
nish  successively as they advance  towards the apex  and
terminate in orifices upon the lamina spiralis.   This cribri 
                    THE LABYRINTH.                 137

form  arrangement of the  modiolus is the Tractus Spiralis
Foraminulosus.  The base of the modiolus  is towards the
meatus auditorius internus, and its point does not go to the
apex of the cochlea but stops short of it, and is expanded
into a cavity  called the Infundibulum, the base of which is
towards the apex of the cochlea.  That portion of the apex
of the cochlea which  covers over the infundibulum is the
Cupola.
  It was just mentioned that the lamina spiralis divides the
cochlea into  two tubes; the septum thus  formed, does not
however run their whole  length, for it ceases  in the infun-
dibulum by a small crooked process of bone, called the Ha-
mulus Cochleae.   The lamina, when examined  by strong
glasses, is seen to  consist of four distinct structures called
its  Zones.  1. The Zona Ossea is next to the modiolus, and
is composed  of two  bony laminae, with  an  intermediate
diploic structure, in  which  are the canals for transmitting
the filaments of the portio mollis or auditory nerve.  2. The
Zona  Coriacea,  on  the outer side of this, the structure of
which is cartilaginous.  3. The Zona Vesicularis,  said  to
contain in  its cells a pellucid  fluid.  4.  The  Zona Mem-
branacea, which is probably only the lining membrane of
the cochlea, and completes  the lamina spiralis on its  edge
next to the periphery of the cochlea. Some very respectable
anatomists pass over this minute distinction in the structure
of the septum,  and merely divide  it into Zona Ossea, and
into Zona Mollis,


           Of the Membranous Labyrinth.

  The whole internal face of the bony Labyrinth is lined
by a very delicate  and vascular membrane, which  is more
distinct during  the early periods of intra-uterine life.  Be-
sides this, there is a  membranous labyrinth, consisting in
three semicircular canals, nearly filling up the cavities, and
having the same shape and general arrangement of the bony
canals; and in two  sacs contained in the vestibule. 
'Ub
NERVOUS SYSTEM.
  The Semicircular Membranous Canals have also at their
ends the elliptical enlargements called ampullae; they ter-
minate by  both extremities in the sac of the superior part
of the vestibule. This sac is generally called, from its shape,
Sacculus Ellipticus;  and by Scarpa, from its function, the
Alveus Communis.   In front of the Sacculus  Ellipticus.
nearer the  cochlea, and  opposite the foramen ovale, is the
Sacculus Sphericus;  it is a  complete bag, having no commu-
nication  with the other, or with  the membranous canals.
Both of the sacs adhere to  the vestibulum at their posterior
parietes.
  The sacs of the vestibule and the membranous semicir-
cular canals are filled with a very  fluid  transparent  liquid.
According to the observations of M. Ribes, it is not neces-
sary to the function  of hearing  that  this fluid should be so
abundant as to distend the membranous labyrinth, inasmuch
as in his dissections  he  met with individuals in whom the
latter was only half filled, air4 yet they had heard very well.
He also met with similar cases in which  the fluid was abun-
dant in the vestibulum, but deficient in the canals, and the
reverse.   Corresponding observations have  been made by
M. Brugnone, of Turin,* where he had adopted the precau-
tion of previously freezing the  bone, so that none of the
fluid could be said to have been  lost by accident.  From the
frequency  with which  this  deficiency  was  observed, his
opinion seems to be well founded, that it is the most natural
state of the labyrinth.
   The parietes of the membranous labyrinth are very thin
and transparent; there is a very loose cellular tissue between
them and the bone, and they are susceptible of being highly
coloured by injection.
   A fluid  of the  same  character with  the  preceding  also
fills the scalae of the cochlea, and extends itself into the bony
vestibulum and the bony semicircular canals  upon the outer
surface of the membranous labyrinth.
♦  Mem. de Turin, 1805—1808. 
THE LABYRINTH.
439
             Of the Aqueducts of the Ear.

  The Aqueducts (Aquaeductus) of Cotunnius, as they are
called, are two small canals which go  through the petrous
bone from the labyrinth. There is one for the vestibule, and
another for the cochlea.
  The Aqueduct of the Vestibulum, commences in the lat-
ter cavity, somewhat in advance of the common orifice of
the two semicircular canals; it goes inwards, and opens on
the posterior face of the petrous bone, behind the meatus
internus.   It enlarges gradually in its course, which causes
it to have somewhat of a triangular shape, and it is lined
by a  continuation of the dura mater.   It is about four lines
long.
   The  Aqueduct of the Cochlea commences in  the Scala
Tympani, near the foramen rotundum and enlarging in its
course terminates on the under surface of the petrous bone,
in the internal margin of the jugular  fossa, at the root of
the little spine which  separates the eighth pair of  nerves
 from the jugular vein.
   The anatomist* from whom these canals were named, and
 who first described them, was under an impression that the
 fluid of the  labyrinth always filled it  completely, and that
 without a sort of waste gate for it on an occasion, the vibration
 of the stapes would be prevented from putting it in motion,
 consequently hearing must cease.  These canals, the exist-
 ence of which is sufficiently obvious in many subjects, were,
 therefore, considered by him as the desired avenues for the
 discharge of the superabundant fluid, and  his theory and
 descriptions were very generally adopted.   Of late years
 the investigation of this subject has been renewed by MM.
 Ribes and Brugnone, and their observations are considered
 by the French anatomists, to have proved conclusively, the
 error into which Cotunnius and others have fallen.
    In regard to the aqueduct of the vestibule, M. Ribes has
 found  it only in three instances emptying into the vestibule;

    * Dominici Cotunnii, Anat. Dissert, de Aquaeduct.  Naples, 1761. 
440
NERVOUS SYSTEM
 for most commonly it leads, after  a course somewhat tor-
 tuous, into the spongy structure of the petrous bone, at the
 posterior part of the vestibule, and smaller canals diverge
 from it in  different directions.   In  the cases where it was
 connected  with, the labyrinth, it was so by several orifices
 leading into  the vestibule, and into the posterior semicircu-
 lar canal.  He has not found this canal in the foetus or till
 some time after  birth, and  from his injections he believes
 that in all cases it and  its branches  are only intended to
 convey blood vessels throughout the  petrous bone and to
 the labyrinth.
   In regard  to the supposed aqueduct of the cochlea, M.
 Ribes has also found it  diverging into collateral branches,
 and occupied by blood vessels, which  are distributed to the
 spongy structure of the petrous bone, and to the tympanum.
   In my own researches on this point., on the dried bones,
 the canals, as described  by Cotunnius, were  closed at the
 labyrinth in  the case of subjects advanced in life; but in the
 middle aged  and  in  infantile specimens, I have been more
 successful in tracing  them fairly into the  labyrinth, and
 have the preparations in  the Wistar Museum.  At the same
 time I think it much more probable that they only contained
 blood vessels, and that Cotunnius was in error.    Besides
 these vascular canals, M. Ribes has described some others
 having the same use.


 SECT. IV.--OF THE NERVES OF THE ORGAN OF HEARING.

  The Nerves which pass through the petrous bone, and
 are either wholly or partially spent upon the organ of hear-
ing come from three sources.  1. The  Auditory Nerve; 2.
The Portio Dura; 3. The Trigeminus or Fifth Pair.
  The Meatus Auditorius Internus conducts the two first and
has its bottom divided by a ridge into two fossae, of which
the upper one is the smaller.  This bottom, it has been ob-
served, corresponds with  the base of the modiolus, and is
cribriform.   One foramen larger than any of the others, and
in  the superior  fossa,  transmits the portio dura or facial 
NERVES OF THE ORGAN OF HEARING.
441
nerve, all the others are occupied  by the  filaments of the
auditory nerve.

   1. The Auditory Nerve divides at the bottom of the mea-
tus into fasciculi of filaments; one of which penetrates into
the vestibulum through the foramina behind that for the por-
tio dura, and is distributed upon the sacculus ellipticus, and
upon the ampulla of the superior and of the exterior mem-
branous canal; other filaments get to the sacculus  sphericus;
and a third fasciculus of filaments is distributed to the am-
pulla of the posterior membranous canal.  These  several
filaments are said to preserve, when they first penetrate into
the bony labyrinth, a fibrous appearance, and are interlaced;
they also penetrate the  parietes of the  membranous  laby-
rinth and have their extremities bathed in its fluid, in which
place they are converted into a soft pulp, resembling mucus
or the retina.
   Another very considerable fasciculus of filaments  pene-
trates into the  canals of the modiolus, and enters through
them into the cavity of the cochlea, along the Zona Ossea,
and between its tables; they terminate also by a soft pulp
on the internal face of  the lining membrane of the cochlea.
One of these filaments, conspicuous for its size, goes through
the central canal of the modiolus and terminates in the in-
fundibulum.*

   2. The Facial Nerve is only connected to the organ of
hearing by sending a  few filaments to the muscles of the
bones of the tympanum.  The  canal of the  petrous bone,
through which it passes, is very crooked;  beginning  at the
larger orifice of the meatus internus in its upper fossa, it
passes outwards until it nearly reaches the vidian foramen,
on the front of the petrous bone; it then turns very abrupt-
ly backwards, forming an angle, and is continued in a cir-
 cuit around the superior  and the posterior parietes of the

   * For a knowledge of the minute distribution of the auditory nerve, the
profession is signally indebted to the distinguished Scarpa, in his Disquisi-
tiones de Auditu at Olfactu.
   V0I. II.—56 
442
NERVOUS SYsTEM.
tympanum, till it terminates in the stylo-mastoid foramen.
Its course is marked by a ridge projecting into the tympa-
num, above the foramen ovale, and passing between the se-
micircular canals and the cochlea.  This canal has been very
much misnamed by the.calling of it the aqueduct of Fallo-
pius, as its only use is to conduct nerves and blood vessels.
It is lined by a delicate fibrous membrane, between which
and its contained parts  there is so little adhesion, that the
latter may be drawn out entire.
  The facial nerve is joined at the vidian foramen  by the
vidian nerve, shortly after which it sends a filament to the
tensor tympani muscle.   As it passes  the base of the pyra-
mid it detaches another filament, which supplies the stape-
dius muscle.   Shortly after this it is abandoned by the vi-
dian nerve, and does not give off any more branches till  it
escapes from  the stylo-mastoid  foramen, when it sends off
a branch, the posterior auricular, (Auricularis Posterior,)
which is  distributed by  filaments, some of which run  into
the mastoid process; others mounting on the side of this pro-
cess, go to the skin  which covers it,  and  to the occipital
muscle; others go to  the concha of the ear,  being spent upon
its skin, upon, the  posterior auricular muscle, and some  of
them, penetrating the pinna, are lost upon the integuments
of the meatus externus.

   3.  The Chorda Tympani or Superficial Petrous Nerve,
is a branch of the Pterygoid branch of the Trigeminus, and
leaves it near the anterior part of the carotid canal of the
petrous bone.  It, as just mentioned under the name of vi-
dian nerve, joins the facial  nerve at the angle of the canal
of Fallopius,  and continues to adhere closely  to it, almost
to the styloid foramen; it then abandons the facial nerve at a
very acute angle, and running  upwards and forwards, gets
into the cavity of the tympanum, on a level with, but a line
or two exterior to the pyramid.   It then crosses the tympa-
num nearly horizontally, between the  long crus of the incus
and the handle of the malleus, adhering to  the  latter so as  to
be affected by its vibrations.  At the fore part of the tympa- 
NERVES OF THE ORGAN OF HEARING.
443
num it anastomoses with some other filaments of the fifth t
pair, by which its size is augmented, but it gives no bran-
ches to the parts contained in the tympanum.   It then is-
sues from the  latter cavity through  the glenoid foramen,
and descending a short but somewhat variable distance along
the ramus of the lower jaw, terminates  by anastomosing at
an acute angle with the lingual branch of the trigeminus.
  To Mr. John Hunter is due the merit of having traced
the continuity and identity of the vidian  nerve with the
chorda tympani.   The continental anatomists, for the most
part, seem ignorant of his observations, and give a very dif-
ferent account of the matter. Some call the vidian nerve the
superficial petrous, consider it to arise from the  facial, and
to anastomose at the  other end with the pterygoid, or the
reverse;  and they very generally agree in regarding the
chorda tympani as a filament from the facial, just before the
latter gets out of the stylo-mastoid foramen.
  The Vidian Nerve  or Superficial Petrous also traverses
the tympanum in another  place.  Just below the posterior
extremity of the Eustachian Canal, there is a small foramen,
which leads upwards to the superior surface of  the petrous
bone, and downwards to a small gutter upon the promontory;
this gutter is converted into  a canal that  opens upon the
under surface of the petrous bone, between the carotid canal
and the jugular fossa.   Through the course indicated passes
a filament from the superficial petrous nerve; this filament
is joined by another  detached from the sympathetic while
in the carotid  canal, and the two  communicate at the base
of the cranium with the ganglion of the glosso-pharyngeal
nerve.*  These filaments were discovered by Professor Ja-
cobson of Copenhagen.

  *  Meckel, Man. D'Anat. vol.  iii. p. 174. Jacobson, Supplements ad
otoia triaro, Act. Hafn. vol. v. p. 292.  An. 1818. 
414                 NERVOUS SYSTEM.
                    CHAPTER  III.

      OF THE ORGAN OF SMELLING,  OR THE NOSE.

  The two preceding senses are so insulated in their offices,
that there can be no doubt of the propriety of considering
them as belonging to the peripheral portion of the nervous
system.   But the nose being, in the human subject, though
not in all animals, associated with the function of respira-
tion, its collocation is less exceptionable.  Without detailing
the considerations which have induced  me to put its de-
scription under this head, I will only mention that I have
been principally actuated by its  office of smelling and  by
its position.
  In common language, the term nose is applied to the part
of the organ of smelling which manifests itself externally;
but a very extensive cavity of the same vertical diameter,
and divided into two equal compartments, exists behind it.
This cavity extends from the  basis of the cranium  to the
roof of the mouth, and  backwards to within an inch and  a
quarter of the vertebrae of the neck.   The nose, externally,
is generally pyramidal, and has its base below; what is tech-
nically called the root of the nose is the part contiguous to
the forehead.  The base, on each side, is marked,  from  the
cheek,  by a semicircular depression; which becoming more
and more shallow at its upper extremity, and increasing its
breadth, is  insensibly lost upon  the  side and point  of  the
nose.  The ala nasi is the swell of the posterior part  of  the
base, being bounded behind by the depression. The base of
the nose offers, on each side, an oblong oval orifice looking
downwards, and having its  long diameter  forwards  and
slightly inwards.  These openings are commonly about two
lines below the floor of the nose, but there is a diversity in
this respect.

   The Nasus Cartilagineus, or the cartilaginous portion of
 the nose, is placed wholly at its anterior extremity,  and 
ORGAN OF SMELLING.
445
serves to elongate the cavity in that direction.   It presents
a vertical cartilage, which is a continuation of the bony sep-
tum;  on each side of this,  there is an oval cartilage, and
behind  and  below the  latter, several distinct and small
pieces of cartilage, which preserve the form of the alae nasi,
and, in  fact,  constitute them.

   The  Cartilaginous  Septum (Septum Cartilagineum) is
placed precisely in the middle line of the nose, and has its
anterior angle projecting beyond the bony orince of the an-
terior naris.   Occasionally, from a faulty conformation, it
inclines more to one side than to the other.  It adheres, by
its superior margin, to the  nasal  lamella of the ethmoid and
 the middle nasal suture,  and  behind to the anterior margin
 of the  vomer.  The  inferior margin is free in the greater
 part  of its extent, but adheres behind  to the suture between
 the maxillary bones.  The anterior margin sends  out, on
 either side,  a triangular plate, the  upper edge of which  ad-
 heres to the inferior margin  of  the  nasal bone, and of the
 nasal process of the upper maxillary.  These plates form  the
 upper  part of the cartilaginous nose, and, from their liga-
 mentous attachment to  the bones, admit of a slight motion
  from side to side.
    The Oval Cartilages,  one on  each  side, are a  species of
  elliptical ring, but deficient or open at their posterior end.
  The external side of the ring is an oblong oval plate, which
  is directed  upwards and backwards.  The internal half of
  the  ring is  much narrower,  and proceeds backwards from
  the preceding part at a very acute angle;  its  superior mar-
  gin is  in contact with the septum, its inferior margin reaches
  below the latter, and  its  anterior extremity is  in  contact
  with its fellow, owing to the cartilaginous septum not reach-
  ing  so far forwards.  The  place of contact of the two  oval
  cartilages to each other, forms  the tip of the nose and the
  columna nasi, and gives the apparent thickness to the lower
  part of the  septum narium before dissection.
    The Alae Nasi, or the convexities on each side of the  base
  of the nose, it  has  been  said,  owe their shape to the pre- 
446
NERVOUS SYSTEM.
 sence of several small pieces of cartilage. Their form, size,
 and number are too variable to  admit of a standard descrip-
 tion; occasionally, they are all  collected into but one carti-
 lage. They serve a similar  purpose with the oval cartilage,
 and with it are the means by which the orifice of the nose
 is kept patulous.  They are deposited  in, and held together
 by a ligamentous membrane. This membrane attaches them
 to  the  lateral margin of the anterior  bony naris, and also
 unites the upper edge of  the external plate of the oval car-
 tilage to the inferior margin of the triangular plate of the
 cartilaginous septum.  It  is  the  length and looseness of this
 ligament which permits such free motion to  the end of the
 nose.   In addition there exists a small ligament described
 by Caldani, which  goes from the posterior  end of the co-
 lumna nasi to the anterior inferior margin of the bony naris.

   The skin which covers the upper half of the nose is loosely
 attached,  by cellular  substance,  to the subjacent parts, but
 it adheres very  closely to the surface of the cartilaginous
 and ligamentous structure, and is abundantly furnished with
 sebaceous glands and  follicles.  The exterior orifices of the
 latter are  apparent, and are often filled with their appropri-
 ate fluid in an inspissated  state,  which, when forced out by
 pressure, assumes the form  of small worms, the blackness
 of the end of which is only dirt.
  There are several muscles destined  to move the cartila-
 ginous  structure  of the nose, which  have been  described
 among those belonging  to the face.
  The  Levator  Labii Superioris Alaeque Nasi, which lies
upon the side of the nose  and comes from the superior part
of the nasal process of the upper maxillary bone, is, besides
its insertion into the upper lip, connected with the ala nasi,
and will draw the latter upwards.
  The Compressor Naris, arising from the ala  nasi by a
small pointed beginning, is  spread out upon the oval carti-
lage so as to cover it, and is inserted into its fellow on the
 middle  line.
  The Depressor Labii Superioris Alaeque  Nasi, by arising 
                  ORGAN OF SMELLING.               447

from the roots of the alveolar processes of the incisor and
canine teeth of the upper jaw, and going to be inserted into
the ala nasi, as well as into the upper lip,  will draw the ala
nasi downwards.
  The  Nasalis  Labii Superioris, or  Depressor Narium,
which is the pointed production from the orbicularis oris, go-
ing into the columna nasi, will draw the latter downwards
and backwards.

   The Mucous Membrane of  the Nose (Membrana Pitui-
taria, Schneideriana) lines the whole cavity of each side
of  the nose, penetrates into the several sinuses and cavities
 communicating with it, and is continuous, at the orifice of
 the nostrils, with the skin, and at the posterior nares,  with
 the mucous membrane of the pharynx.
    It is not of essential importance to  begin to trace  its
 course from any particular point, but, for the sake of per-
 spicuity, we assume the floor of the nostril, which it covers
 in a smooth even manner.  From this  it ascends on the
 septum narium, which it  covers also  smoothly without
 forming any fold or duplicature, and adheres so loosely that
 it may be detached with great facility.   Behind, it covers
 the body of the sphenoid bone, and lines its cells; in front,
 it covers  smoothly the  ossa nasi and nasal processes of the
 upper maxillary bones, and also the cartilaginous  nose.
 Above, it is reflected upon the cribriform plate of the eth-
 moid bone, and blocks up all its foramina.   At this point,
 the olfactory nerves seem to terminate  on its surface and
 adhere very closely to it.
    From the cribriform plate, the Schneiderian  membrane
 passes to the  cellular  part  of the ethmoid,  and  covers
 smoothly its anterior half.   But behind, as it passes over
 the upper spongy bone,  a pendulous duplicature is formed
  along its inferior margin; and is continued beyond the bone,
  backwards as far as the spheno palatine foramen.  It then
  lines the upper meatus and  the  posterior  cells of the eth-
  moid, and is extended upon  the convex  surface  of the mid-
  dle spongy bone.  At the inferior  margin of the latter, it 
d48                NERVOUS SYSTEM.
forms another loose and  somewhat pendulous duplication,
which does not go beyond the posterior  extremity of the
bone.   The  membrane is then reflected  into the  middle
meatus of the nose, and penetrates  into the maxillary  sinus
which it lines completely.   The orifice  through which it
enters, is about the size of a crow-quill; is variable in its si-
tuation,  being sometimes in the  middle of the meatus,
sometimes more forward, and on other occasions higher up
and concealed by irregularities, in  the conformation of the
ethmoid.  This orifice, which was  found to be so large and
jagged in the dried bone,  is  reduced to its present size en-
tirely by the mode of reflection of  the mucous membrane
over its  margins.  In front of the latter orifice, beneath the
anterior margin of the middle turbinated bone, the mucous
membrane is reflected into the anterior ethmoidal cells  by
one or more foramina, and through the  most anterior of
these cells into the frontal sinus.
   From the middle meatus, this membrane passes upon the
lower turbinated bone so as to cover it, and also to form a
loose duplication along its inferior margin; it then lines the
inferior meatus of the nose,  and  is continued on its floor
into the  part from which its description commenced.  Un-
der the anterior part of the inferior spongy bone, this mem-
brane is  continued into the lining membrane of the lachry-
mal sac, and there forms a  fold, frequently  resembling a
valve.   Along the posterior margin  of  the vomer, the
membranes of the two nostrils are continuous.
   The pituitary  membrane, in its structure and appearance,
resembles other mucous membranes; its colour, however, is
naturally of a deeper red.  It  consists of two laminae, which
cannot be readily separated; the  one next to the  cavity of
the nostril has the mucous structure, the exterior  one is
fibrous,  and resembles the periosteum of other parts of the
body.   This composition is best seen on the part belonging
to the septum narium.
   By floating the  pituitary membrane  in water its mucous
lamina is made  to exhibit, very  satisfactorily, the villous
and  spongy appearance.   This is  particularly evident on 
                  ORGAN OF SMELLING.              449

the turbinated bones.  Its whole surface  is studded  with
pits or follicles of various  sizes,  irregularly arranged, and
resembling pricks made into a plastic substance with the
point of a pin.   From these cavities or cryptae proceed the
mucus of the nose.  In the thickness of the pituitary mem-
brane, there exist numerous and thickly set glands, of a
size so small that they escape  common  observation, but
their existence is generally admitted, both on the authority
of anatomists who have described them,* and on the prin-
ciple of their being always the concomitants  of mucous
membranes, t
   It is owing to the great abundance of blood vessels in this
membrane, to their very superficial course, and  to the ha-
bitual residence of  blood  in them, that it always presents
 a deep  red  colour  in  the living state.   These blood ves-
 sels  bleed very freely  from slight mechanical  causes, and
 are also disposed to congestions, which are relieved by the
 blood  being poured out  through their exhalent orifices,
 without laceration or any  solution of continuity.
   Though the description just given corresponds with the
 texture generally of the pituitary membrane, yet there are
 modifications of the latter at particular points which it does
 not fully suit.   For example; at the anterior orifice of the
 nostril it is insensibly changed  into a thin skin, furnished
 in the male adult with stiff hairs (Vibrissas;) and in  all the
 sinuses it is more thin and white than elsewhere, being also
 smooth and shining, and not presenting  clearly the little
 pits which are so distinct in the nose.  The surface which
 adheres to the sides of the sinuses,  is destitute of a fibrous
 structure, and is so loosely attached that it peels off  with a
 very inconsiderable force.  When the membrane of the si-
 nuses is inflamed,  it then thickens, admits more red blood,
 and is thus brought to resemble the pituitary elsewhere.
    It is extremely difficult to assign a proper use to the si-
  nuses entering into the nose, for, according to Dessault, the
  sensation of smell  does not exist in them.   Bichat believed

             * Ruyschii, Epist Anat.  Probl. vii.     Mayer,
             f Bichat, Anat. Descrip.
Vol.  II.—57 
450
NERVOUS SYSTEM.
 that they, by being filled with  air charged with odorous
 particles, were reservoirs of the latter,  serving to prolong
 the sensation of smell, which would have been too fugitive
 if  it had depended only on the passage of air during respi-
 ration.  Another problem in regard to these cavities, is the
 manner in which they discharge the mucus which they se-
 crete.   Perfectly rigid and unyielding, and so situated that
 the most frequent attitudes of  the  head  would rather serve
 to  retain, than to discharge the contents of most of them
 by gravitation, we yet seldom see more than their surface
 smeared with mucus, and accumulations of  it are  quite un-
 common, except in  the  diseased state.   This secretion in
 them, it is to be observed, is much less abundant  than it is
 in  the nose.


      Of the Nerves of the Pituitary Membrane."

  The  pituitary membrane  is  furnished with nerves from
two sources; from the olfactory, and from the fifth paiu.
  The Olfactory Nerve having formed  its bulb, which re-
poses in the ethmoidal fossa, sends off from the under sur-
face of  the bulb,  the succession of filaments which pene-
trate to the nose through the cribriform plate.  The latter,
when examined from the upper surface, has its foramina ar-
ranged into two rows, one next to the crista  galli, and the
other next to the cellular portion of the ethmoid.   Each
row consists  of about six or eight  foramina, and  between
these rows there  are  other  foramina, smaller, and not so
much in a line with each other.  The same cribriform fo-
ramina, when examined from  the  cavity of the nose, are
more  numerous,  especially  those  belonging to  the  two
rows, in consequence of the latter branching out  below into
several  canals,  which  may be  seen very distinctly on the
side of the base of the nasal lamella, and  on that  of the cel-
lular portion  of the ethmoid.
  The distribution of the olfactory nerve corresponds with
this arrangement of the cribriform  plate, for it has three
Antonii Scarpa, Anatom. Annotationes, Lib. ii. 
                                 451
ORGAN OF SMELLING.
rows
   n of branches proceeding from the under suiface of its
bulb, each branch going through  its appropriate fo men
and subdividing in it, but  sometimes two filaments pass
through the same foramen.  In a short space after their ori-
gin,  they become  invested  by sheaths of the dura mater,
which  are extended a considerable distance, and  by a close
adhesion to the nerves, make them appear much larger be-
low than they are  at  the  roots.   When  the  nerves reach
the cavity of the nose they anastomose  together,  and  de-
scending between the bone  and  the  pituitary membrane,
they ramify into an infinitude of small  branches,  the ter-
minating filaments of which reach the nasal surface of  the
membrane.
   The Internal Branches, or those next to the crista galli,
 diverge from the cribriform plate, and pass downward be-
 tween the septum and the pituitary membrane: where they
 first appear in the nose, there are some  few adhesions or
 anastomoses between them;  but their filaments  afterwards
 keep  perfectly distinct, and, spreading  themselves out on
 the pituitary membrane of the septum, make an appearance
 resembling a  flat camel's-hair pencil.   The  middle  ones
 are the longest, and may be traced almost to the floor of the
 nose; the anterior are shorter somewhat; the  posterior do
 not reach obviously below the middle of the septum.
   The External Branches  have  a very different  mode of
 distribution.   While still in their canals they divide  into
 many filaments,  which  anastomose  frequently with each
 other, and when they have fairly got into the cavity of the
 nose, the same frequency of anastomosis continues, so that
 they form a network of numerous and small meshes, which
 prevail from the cribriform plate to the inferior margin of
 the middle  turbinated bone.  Their filaments cannot be
 traced below the latter line, and  therefore do not descend
 so low as the filaments of the internal row, neither are  the}
 so close to each other.   They do not penetrate  to the eth-
 moidal  cells.   The posterior ones are very abundant on
 the upper turbinated bone,  and incline  backwards in  their
  descent; the anterior are also abundant on the flat anterior 
452
NERVOUS SYSTEM.
half of the ethmoid, and when they get below the  line of
the upper meatus, they extend backwards  to  the posterior
end of the middle turbinated bone, and to its inferior mar-
gin.  On this bone they are less abundant than above  it;
their meshes are larger, and their  distribution  is confined
to the Schneiderian membrane covering its convex surface.
   The filaments of the middle row associate themselves in-
discriminately with those of the external and of the inter-
nal row, according to local convenience.

   The other nerves of the Pituitary Membrane come from
the first and from the second  branch  of  the Trigeminus.
The first branch gives off from its nasal branch the nerve
called Internal Nasal, which penetrates from the orbit into
the cavity of the cranium, through the anterior  internal or-
bitary foramen, and lies  covered by the dura mater, at the
side of the crista galli; thence it passes into  the cavity of
the nose, through the most anterior foramen of the cribri-
form plate.

   This  Internal Nasal Nerve  (Nasalis Internus) having
got into the nose, divides into two fasciculi, an internal and
an external. The internal descends along the anterior margin
of the septum, between the mucous membrane and the bone,
and after a short course is divided into two filaments, one
of which, applying itself to the posterior face of the os nasi,
terminates by smaller  filaments in the integuments of the
lower part of the nose; the other  filament continues along
the margin  of the septum to the lower part of the  latter,
where it terminates by smaller filaments.  The external fas-
ciculus of the Nasalis  Internus gives off early a filament,
which descends along a groove on  the posterior face of the
nasal bone, and winding over the lower edge of the latter, or
passing through a foramen in it, is lost upon the integuments
of the corresponding part of the nose.  Other filaments from
the external fasciculus descend upon the mucous membrane,
along the external anterior part of the nose, or  that which
corresponds with the nasal  process of the upper maxilla, 
ORGAN OF SMELLING.
453
and terminate near the  anterior extremity of the inferior
spongy bone: they are three or four in  number.   The in-
ternal nasal nerve, is also said to send one or more filaments
to the  frontal sinuses, but they are so  fine that  doubts of
their existence are entertained by Bichat, though they are
admitted by J. F.  Meckel.
  The Spheno-Palatine  Ganglion,  a part of the  second
branch of the Trigeminus, detaches  to  the nose, through
the spheno-palatine  foramen, several filaments.   One of
these, discovered by Cotunnius, and admirably delineated
by Scarpa and by John  Hunter, called the Naso Palatinus,
runs across the front of  the  sphenoidal sinus to  the upper
posterior part of the septum narium, beneath the mucous
membrane.   It  then descends obliquely along the septum
to the foramen incisivum, and passes through it to the roof
of the mouth.   In many cases, however, a distinct foramen
is formed in the middle palate suture for it, anterior to the
foramen  incisivum.  The nerve of the left side is anterior
to that on the right.   When the two reach the roof of the
mouth, or are near it, they unite  to form  a little swelling
called the naso-palatine ganglion,* from  which several fila-
ments arise, and are  spent upon the  membranous caruncle
at this point, and upon the contiguous part of the palatine
membrane.
  The spheno-palatine ganglion sends several filaments to
the mucous membrane of the upper spongy bone and of the
upper meatus, and to that of the posterior end of the middle'
spongy bone. The palatine nerve, one of its largest branches,
in descending along the posterior or palatine canal to the
soft palate of the mouth, also contributes  to the supply of
nerves to  the nose.  Shortly after it has arisen  from the
ganglion, it sends one or more filaments to the middle spon-
gy bone, and  to the superior part of the lower spongy bone;
and when it has  got in its descent on  a level with the pos-
terior end of the latter,  it detaches another filament, which
supplies the mucous membrane, along the inferior margin
of this bone.
* J. Cloquet, loc. cit. 
454                NERVOUS SYSTEM.
  An opinion advanced by Mery about the close of the se-
venteenth century, has  lately been revived by M. Magen-
die, of Paris, that the olfactory nerves are not those which
communicate  the  impressions of odorous bodies.  In con-
tradiction, however, to his experiments, it should be stated,
that several respectable anatomists have seen cases where
the privation of the sense of smell during life, was found,
upon examination after death, to be attended with the ab-
sence of the olfactory nerves.


           Of the Blood Vessels of the Nose.

  The extreme vascularity of the Schneiderian Membrane
is derived from several  sources.   The  Internal  Maxillary
Artery sends through the Spheno-Palatine Foramen a large
branch, which is distributed upon the septum and upon the
spongy bones.  The palatine artery also supplies this mem-
brane with one or more  small  branches.   The Ophthalmic
also sends the anterior and the posterior ethmoidal branches
to it, from the orbit of  the eye.  The  infra-orbitar artery
likewise contributes  to  its vascularity  by one  or more
branches, sent off in its course through the  infra-orbitar
canal.
  The veins follow the  course and distribution of the arte-
ries.  Some of them, however, unite with trunks called the
emissaries of Santorini, which reach the sinuses of the brain
through the foramen ovale  and rotundum of the  sphenoid
bone. 
BOOK  IX.
                      PART IV.

            Special Anatomy of the Nerves.


                    CHAPTER I.

         OF THE NERVES OF THE ENCEPHALON.

               SECT.  I.--NERVUS OPTICUS.

  The Optic Nerve, as mentioned  in  the account of the
basis of the brain, gets into the orbit by the optic foramen,
and is there entirely surrounded by the  origins of the mus-
cles of the eyeball.  It then describes a slight curvature, of
which the convexity is outwards,  and runs forwards for an
inch,  when it penetrates into the ball of the eye, where it
gives origin to  or  expands into the retina.   Between  the
muscles and it,  except at their origins, there is a  mass of
adipose matter.


            SECT.  II.--NERVUS MOTOR  OCULI.

  The Nervus  Motor Oculi, or third pair, having reached
from  the basis of the brain to the external side of the caver-
nous sinus, is placed there within and above the ophthalmic
nerve and the sixth pair; it then changes its direction, and
penetrates through the sphenoidal  fissure into the orbit, on
the outer side of these nerves, and below them.
  The motor oculi  divides, in the sphenoidal fissure, into
two branches, one above the other.  The first crosses over the 
456
NERVOUS SYSTEM-
optic nerve and the nasal branch of the ophthalmic, having
some anastomoses with the latter, and then distributes its
filaments upon the rectus superior muscle; some of them also
penetrate the latter  to get to the  levator palpebrae.  The
second branch  is much larger than the first.  It passes be-
tween the optic nerve and the  rectus inferior  muscle, and
is subdivided into three fasciculi:  one for the rectus inter-
nus  muscle; another for  the rectus  inferior; and  a third,
which is the longest and the smallest, for the obliquus infe-
rior muscle.  The latter fasciculus,  not  far from its root,
gives off a filament, which, going  along  the external mar-
gin of the optic nerve, runs  into  the  posterior margin of
the lenticular ganglion, and is its short root.


            SECT. III.--NERVUS TROCHLEARIS.

   The Nervus Trochlearis, or fourth pair,  having got into
its canal in  the cavernous sinus, as it goes along the inter-
nal margin of the ophthalmic nerve, receives there a small
filament from it.*   It then  rises a  little, and enters the or-
bit at the internal extremity of  the sphenoidal  fissure; and
going forwards, next to the periosteum of the upper part of
the orbit, it enters into the superior oblique muscle of the
eye,  near its  middle, and  is distributed upon it.   This
nerve augments in volume as it advances towards its desti-
nation.


          SECT. IV.--NERVUS MOTOR EXTERNUS.

   The Nervus Motor Externus, or  sixth pair, having got
into the  cavernous sinus, is placed there at the external side
of the internal carotid artery, and adheres closely to it.  It
there sends off one or more filaments, which follow the in-
ternal carotid  artery through its canal and anastomose in
their descent with  a  branch of the pterygoid nerve: the
junction of these two forms the  upper end of the great sym-
* Soemmering', Icon. Ocul. Human. 
                  NERVUS TRIGEMINUS.              **°'

pathetic nerve, and runs down to the superior cervical gan-
glion of the sympathetic in two or more filaments.  The
sixth nerve  enters the orbit through the sphenoid fissure,
and is there closely connected with the nervus motor oculi
and the nasal nerve.   It penetrates into the substance ol the
rectus externus muscle, and is entirely distributed upon it;
with the exception that sometimes it sends a filament to the
ophthalmic ganglion.
         SECT. V.--OF THE NERVUS TRIGEMINUS.

  This nerve having formed the ganglion of Gasser (Plexus
Gangliformis) on  the side of the petrous  bone, then di-
vides, as mentioned, into three large fasciculi, the foremost
of which is the Ophthalmic  Nerve: the second fasciculus
is the Superior Maxillary;  and the third the Inferior Max-
illary Nerve.
  The Ophthalmic Nerve or the first branch of the trigemi-
nus, is smaller than either of the  other two branches, and
comes from the  superior  part of  the plexus gangliformis.
It passes along the external border of the  cavernous sinus,
and penetrates the orbit through the sphenoidal fissure, on
the outer side of, and near the motor oculi.
  In its whole course it is united to the trochlearis nerve by
close cellular membrane, and  does not give off any ramifica-
tions before it reaches the orbit, with the exception of the
filament  sent to  the trochlearis  nerve.  While engaged  in
the sphenoidal  fissure it divides into  three  branches; the
nasal, the lachrymal, and the frontal.
  The Nasal branch of the ophthalmic, is between the other
two in size.  It  ascends obliquely above the optic nerVe to
o-ain the  internal face of the orbit of the eye, and then passes
forwards just below the superior  oblique muscle, involved
in a quantity of adipose matter.  Shortly after its origin the
nasal nerve detaches a branch (the ramus ciliaris) which,
situated  at the external margin of the optic nerve, runs into
the ophthalmic ganglion and constitutes its long root; it then
  Vol.  II.—58 
458
NERVOUS SYSTEM.
sends off one or more filaments, which, without communi-
cating with this ganglion, penetrate  into the eyeball, and
are amongst the ciliary nerves which have been described.
  The nasal nerve continuing to pass forward along the in-
ternal parietes of the orbit, when it reaches the anterior in-
ternal orbitary foramen,  detaches through it the  internal
nasal or ethmoidal branch, which thus getting into the ca-
vity of  the cranium, goes along side of the crista galli, and
then passes into the nose  through the foremost hole of the
cribriform plate. It then descends along the anterior part of
the nose,  on the outer side of the Schneiderian  membrane,
and is spent by ramifications  upon the contiguous portions
of the latter. Some of its terminating branches reach the tip
of the nose and the alae. *
   The nasal nerve, after this branch is sent off, is frequently
called external nasal,  or nervus infra-trochlearis.  It  con-
tinues to advance along the under margin of the trochlearis
muscle  and gets to the  trochlea, near which it divides into
an upper and an under ramuscle;  from them filaments pro-
ceed to  the upper  and under  eyelids, to the lachrymal sac,
the caruncle, the tunica conjunctiva, and the muscles on the
root of  the nose.  These filaments anastomose with the ter-
minating branches of the frontal nerve, the facial, and the
infra-orbitary.  According to  Dr. G. Trasmondi,tof Rome,
two filaments may be traced very distinctly from the exter-
nal nasal nerve, to the tensor  tarsi muscle of the lachrymal
sac. They adhere to the muscle by means of cellular struc-
ture,  and  pass  on  to  its bifurcated extremities and to the
puncta lachrymalia.
  The Frontal  Nerve  is the  largest of the three branches
of the ophthalmic.  It proceeds forward between  the levator
palpebrae superioris and the contiguous part of the orbit, and
in this course is divided into two branches, the internal and
the external frontal  nerve.   The former approaches the

  * See Nerves of Nose.
  ■j- Intorno la scoperta di due nervi del Occhio umano ragguaglio del Dr.
Giuseppe Trasmondi Professore di Anatomia Practica nel  ven. ospidale
della Consolazione. Roma,  1823. 
                  NERVUS TRIGEMINUS.              *°J

trochlea of the upper oblique muscle, and detaches a filament
to join with one from  the nasal nerve.  Other filaments are
detached to the upper eyelid, some of which anastomose
with filaments  from  the  lachrymal  nerve.  The  internal
branch of the frontal then issues from the orbit just by the
trochlea, and in ascending is lost upon the occipito-frontalis,
the corrugator supercilii, and the orbicularis.  The external
branch of  the  frontal issues from the orbit, through the
supra-orbitary foramen.   It quickly detaches a filament,
which goes outwardly to anastomose  with the facial; the re-
maining part of  the  nerve is distributed to the occipito-
frontalis, to the  corrugator supercilii, to the integuments
of the forehead, and to the scalp.  This distribution, accord-
ing to Bichat, is  best  followed by detaching the skin, mus-
cles, and periosteum,  from  the cranium, from behind for-
wards as far as the orbit.
   The Lachrymal Branch of the ophthalmic nerve goes for-
wards along the external side of the orbit near the  superior
margin of the rectus externus muscle.  In this course it sends
off a  filament through the  spheno-maxillary fissure which
unites with one from  the second branch of the fifth pair; it
afterwards sends off another filament, which passing through
a foramen in the  malar bone, anastomoses with a filament of
 the facial nerve.   What remains of the lachrymal nerve is
 then  distributed  by several filaments  upon the  lachrymal
 gland, the  upper eyelid,  and some of them reach the con-
junctiva.


           Second Branch of the Trigeminus.

   The Second Branch of the Fifth Pair, (Nervus Maxilla-
 vis Superior,) arising from the middle of the plexus gangli-
 formis,  or  ganglion of Gasser, and  also from the  common
 trunk formed from the anterior and posterior roots of  the
 trigeminus, gets  from the cranium through the foramen  ro-
 tundum of the sphenoid bone.  While still in the cranium,
 it sometimes forms an anastomosis, described by Laumonier,
 with the beginning of the sympathetic nerve, but generally 
460
NERVOUS SYSTEM-
it does not detach  any filament till it reaches the pterygo-
maxillary fossa.
  At a short distance after its exit from the cranium, it gives
off a small filament, the Nervus Subcutaneus Malae, which
ascends into the orbit through the spheno maxillary fissure,
and then divides.  One of the branches, the malar, anasto-
moses with the lachrymal nerve, and leaves filaments with
the lachrymal gland; it then gets, by one or more filaments,
through the holes of the malar bone to the face, and  termi-
nates on the orbicularis muscle  and the skin of the cheek,
anastomosing with the extremities of the facial  nerve. The
Other branch, the temporal, gets into the temporal fossa by
penetrating the  internal part of the malar bone, and having
anastomosed  with a branch of *he inferior maxillary nerve,
it goes outwards and  backwards, becomes superficial by pe-
netrating the temporal aponeurosis, and terminates on  the
integuments  of  the temple, anastomosing  there with  the
branches of the  facial nerve.
  The superior maxillary then divides into two trunks much
larger than the preceding, and of a volume nearly equal;  the
Infra-Orbital and the  P tery go-Palatine.

  The Infra-orbital (Nervus Infra-Orbit alls) passes for-
wards, with a slight ascent, to the posterior part of the orbit,
and enters the infra-orbitar canal.  As it is about engaging in
the latter, it detaches a considerable  branch, the Posterior
Dental.  This branch descends a little distance, externally,
along the posterior parietes of the maxillary sinus, then  pe-
netrates into the cavity of the latter.  It terminates by fila-
ments, some of which supply the lining membrane of the an-
trum ; others pass through the little canals leading to the three
large grinders and enter the roots of the latter;  others go to
the corresponding gums.   One branch goes along the outer
side of the sinus  to  *anastomose with the  anterior dental
nerve.  The posterior dental, before it enters the bone, also
detaches a branch of some size, which winds around the tu-
berosity of the maxillary bone, and is spent upon the bucci»
nator muscle and upon the gums. 
NERVUS TRIGEMINUS.
461
  The infra-orbitary nerve afterwards, in its course through
the canal, sends off the anterior dental  nerves from one or
more roots.  Some  of them detach  fibres  to the  mucous
membrane of the nose, where it covers the anterior part of
the inferior turbinated bone.  With this exception, they are
distributed, through their appropriate canals in the bone, to
the incisor and canine teeth, and to the corresponding gums.
The small molar teeth are most frequently supplied  by a
union of filaments, from the anterior and posterior dental
nerves.
   The infra-orbitar nerve, on issuing from the infra-orbitar
foramen,  is  most frequently found  already divided into
several fasciculi, which may be classed into superior and
into inferior.   The  former, called  Palpebral, radiate, ex-
ternally and internally,  into filaments which supply the
lower eyelid.   One of these filaments may be traced to the
end of the nose, where it anastomoses with the internal na-
sal branch of  the ophthalmic;  another, which terminates
about  the internal angle of the eye, anastomoses there with
the external nasal nerve.  Others, of  its terminating fila-
 ments, anastomose with the extremities of the facial nerve
 on the eyelid.   The inferior fasciculi  are more numerous
 and large than the superior.  They descend upon the face,
 covered by the levator  muscles of the upper lip, and from
 their  distribution are called Labial.   The most internal of
 these fasciculi terminate on the skin, the muscles, and  the
 beginning of the mucous membrane of the nose, where they
 anastomose with the extremities of the internal nasal nerve.
 The middle fasciculi go to the muscles of the upper lip and
 the skin of the latter, and to its mucous glands.   The ex-
 ternal fasciculi go to the zygomatic muscles and to the con-
 tiguous skin.   All  the foregoing branches of the  infra-or-
 bitar nerve  anastomose with the extremities of the facial,
 and are so minutely distributed to the skin  and muscles of
 the, face, that it would require a very protracted description
 to point them out particularly.

    The Pterygo-palatine Nerve (Nervus Pterygo-palati-
  /ivs) descends, as a single or a double trunk, from its root 
462
NERVOUS SYSTEM.
 to the outside of the  spheno-palatine  foramen, and there
 forms the ganglion of Meckel,*1 or the spheno-palatine gan-
 glion, the existence of which is not constant.   From this
 ganglion, or from the nerve itself, proceed several branches.
   A filament, described by Bock, is detached from it, which
 enters into the sphenoidal sinus to be distributed on its li-
 ning membrane, and sometimes to anastomose with the mo-
 tor externus oculi.
   Then arises the spheno-palatine branches, which enter the
v nose through the spheno-palatine foramen, and are distribu-
 ted upon the mucous membrane of its septum  and turbina-
 ted portions, after the  manner described in the account of
 the nose.
   From the inferior part of the ganglion arises a recurrent
 branch (Nervus Vidianus, recurrens, pterygoideus) which
 goes backwards through the pterygoid foramen of the sphe-
 noid bone.   From it there arise some filaments, which get
 to the mucous membrane about the anterior orifice of the
 Eustachian  Tube, either through the spheno-palatine fora-
 men, or by small foramina in the  pterygoid process of the
 sphenoid bone.  They are  sometimes united  into a single
 trunk,  called pharyngeal by  Bock.   The vidian nerve,
 while still in  its  canal, then divides into two trunks, the
 superficial,  and the deep petrous.
   The Superficial Petrous (Nervus Petrosus Superficialis)
 traverses the cartilaginous matter at the point of the petrous
 bone, in the anterior foramen lacerum of the basis of the cra-
 nium, gets there  into the cavity of the latter, continues its
 progress backwards on the superior face of the petrous bone,
 in a gutter marked on  the bone, and disappears through the
 vidian foramen.  It in a short space reaches the aqueduct
 of Fallopius, and  then continues to adhere to the facial nerve
 till the  latter almost reaches the stylo-mastoid  foramen;  it
 then  abandons the facial nerve, and, as mentioned in the
 account of the ear, traverses the tympanum under the name
 of chorda tympani, and finally emerging at the glenoid fora-
 men, it runs to associate itself with the lingual branch  of
                  * Discovered by Meckel, 1749. 
NERVUS TRIGEMINUS.
463
the trigeminus.  The superficial petrous in the  early part
of its course, at the point of the petrous bone detaches one
or more filaments to the sympathetic in the carotid canal.

  The Deep  Petrous  (Nervus  Petrosus  Profundus) is
larger than the other.   It also  penetrates through the car-
tilaginous matter at the point of the  petrous bone, and en-
ters the cavity of the cranium  under the dura mater.  It
then advances to  the  internal  carotid artery, and anasto-
moses there with a filament from the motor externus.  This
anastomosis is commonly called the beginning of the sym-
pathetic nerve.

   The  Palatine Nerve (Nervus Palatinus, naso-palati-
nus)  proceeds from  the inferior  part of the ganglion of
Meckel, and gets to the soft palate of the mouth through
the posterior  palatine foramen.  In this course  it detaches
several filaments to the Schneiderian membrane, which reach
it either through the spheno-palatine foramen Or by perfo-
rating the nasal lamella of  the  palate bone.  These are de-
scribed in the account of the nose.
   The trunk  of the palatine nerve, having reached the roof
 of the mouth, bends forwards, and is  divided into many
 filaments, some of which  are distributed along the gums of
 the upper jaw others are  distributed on the  lining  mem-
 brane of the hard palate and upon its mucous glands.
   There are two  other nerves, which arise either immedi-
 ately from the palatine, or from  the ganglion of Meckel,
 and go to  supply the soft  palate.   They are  called  the
 smaller palatine.   One  of them,  having proceeded for  a
 short distance in the posterior  palatine  canal, departs from
 it in a little canal of its own, which opens behind the hook
 of the internal  pterygoid process.   It then radiates into
 filaments, which supply the tonsil  gland and the muscular
 and membranous structure of the soft palate.  The other
 smaller palatine also traverses,  after the same  manner, its
 own canal, and is likewise distributed  to the tonsil gland
 and to the soft palate. 
464
NERVOUS SYSTEM.
           Third Branch of the Trigeminus.

   The Third Branch of the Trigeminus (Nervus  Infra-
maxillaris)  is the largest of the three.   It arises from the
posterior inferior part of the ganglion of Gasser, and having
anastomosed  with the cavernous ganglion of the sympathe-
tic nerve by  filaments, which  are not constant, it emerges
from the cranium through the  foramen  ovale of the sphe-
noid bone.   A portion of this  branch does not enter into
the composition of the ganglion of Gasser,  but proceeds
immediately  from the pons varolii.
   The inferior maxillary nerve, at its exit from the fora-
men ovale, is covered by the pterygoideus externus muscle,
and commonly divides there into two branches, one ante-
rior and the other posterior.

   The anterior  branch, which is  much smaller than  the
other, radiates into  five fasciculi; the masseter' nerve,  the
two temporal; the buccal; and the pterygoid.
   a. The Masseter  Nerve is directed horizontally outwards
and backwards, along the external margin of  the pterygoi-
deus externus, and  in front of the  temporo-maxillary arti-
culation: it leaves some filaments with the latter, and then
passing  between the insertion of the temporal and of the
external pterygoid muscles,  over the concave edge of the
bone, between the condyle and the coronoid process of the
lower jaw, it passes into the substance of the masseter mus-
cle, and is distributed through it.
   b.  The two Temporal branches arise by a common fasci-
culus, but sometimes differently.  They pass outwards ho-
rizontally between the external pterygoid  muscle and zy-
gomatic fossa.  They then ascend on  the side of the tem-
poral bone, between it and  the temporal mus le, and are
distributed through  the latter  by a great number of fila-
ments.  Some of these filaments penetrate the aponeurosis,
to anastomose with the superficial temporal nerves  And one
of them anastomoses with that branch of the superior max-
illary'which  sends filaments to the lachrymal  gland,  and 
NERVUS TRIGEMINUS.
465
afterwards escapes from the orbit,  through the foramina in
the malar bone, into the temporal fossa.   It is at the latter
place that the anastomosis occurs.
  c. The Buccal Branch is the largest of the five.   It ad-
vances between the pterygoid muscles,  to  which it fur-
nishes a few filaments, and then descends between the tem-
poral and external pterygoid  muscle, to the  posterior part
of the buccinator.  It is principally distributed on the lat-
ter, upon the buccal glands,  and the corresponding part of
the lining membrane of the mouth.   Some of its branches
advance  under  the integuments of the  face,  as far  as the
commissure of the lips to the muscles there, and anastomose
with the facial  nerve.
   d. The Pterygoid Branch is the smallest, and is distri-
buted principally on the internal pterygoid muscle.

   The posterior branch of the inferior maxillary nerve is so
large, that it looks like a continuation of the trunk.  It is
divided  into the superficial temporal, the inferior  dental,
 and the  lingual nerves.
   a.  The  Superficial  Temporal  Branch is formed by  a
 union of two  fasciculi, between which, passes  the  middle
 artery of the  dura mater;  the inferior of  these fasciculi
 comes from the  inferior dental nerve.    The nerve  is di-
 rected outwardly, and winds horizontally around the poste-
 rior face of the  neck of the condyle of the lower jaw, be-
 tween it and the meatus auditorius externus.  It is there di-
 vided into several small fasciculi, two or three of which pene-
 trate into the substance of  the parotid gland, and anastomose
 with the facial nerve or its ramifications; one or two others
 go backwards, penetrate between the bony and the cartila-
 ginous meatus to the  auditory canal, and are dispersed by
 fine filaments  upon the concha, and the meatus externus*
 According to  Bock,  one of these  filaments  supplies the
 membrane  of the tympanum, and also anastomoses with the
 chorda tympani.  Another branch of the superficial tempo-
 ral, which  is the largest of any, traverses the parotid gland,
 and thereby becomes superficial,  just in front of the exter-
 nal ear.  It then divides into filaments, which follow the
    Vol. II.—59 
160
NERVOUS SYSTEM.
course of the superficial temporal artery, and thereby sup-
ply the  middle part of the  integuments on the side of the
head.   It anastomoses  with the filaments  of the  frontal
nerve, and with those of the occipital.
  b  The Inferior Dental Nerve is placed between the other
two branches, and exceeds them in size.   It descends be-
tween the two pterygoid  muscles, towards the posterior
mental  foramen.   Just above the latter it detaches a small
branch,  the  mylo-hyoid, which  occupies the small gutter
on the bone leading  downward  from the  posterior mental
foramen.  This branch sends a filament to the submaxillary
gland, then  passes between the anterior belly of the digas-
tric  muscle and  the mylo-hyoideus,  to both of which it
gives filaments, and finally winding over the base of the
lower jaw in front, it is lost upon the muscles of the chin.
  The inferior dental nerve then enters the posterior men-
tal foramen,  and  divides into two branches, which run pa-
rallel with one another, through the canal in the middle of
the spongy structure  of the bone,  and send a great number of
anastomotic  filaments to each other.  One of the branches,
the dental, properly  speaking, as it  passes along the ends of
the roots  of the  teeth, detaches a  filament to each root,
from  the last grinder to the first incisor tooth  inclusively;
it also sends a filament to the gum intermediate  to every two
teeth. All of these filaments arise from the dental nerve, at
places behind the points of destination, so that they have,
before reaching the  latter,  to run  forwards and upwards
through little canals  in the  cellular structure of the bone.
  The other branch  of the  inferior dental nerve is the men-
tal; it does not advance so  far forward in  the bone as the
preceding, but issues from it at the anterior mental fora-
men, and immediately is divided into two fasciculi, the in-
ferior labial  nerves.   The  internal  fasciculus is distributed
by filaments uppn the muscles of the chin and lower lip,
the contiguous lining membrane of the mouth and  the la-
bial  glands.   The external fasciculus rises upwards and is
distributed on the muscular structure,  about the under part
of the commissure of the lip, and  to the contiguous lining
membrane and glands of the mouth. 
NERVUS TRIGEMINUS
467
  c.  The Lingual Nerve descends in company with the in-
ferior dental, but in advance of it and diverging  slightly.
While between  the two pterygoid muscles it receives the
chorda tympani at a very acute angle.   It then  passes to-
wards the side of the root of the tongue, deeply concealed
by the angle of the lower jaw, and above the submaxillary
gland, to which it gives some considerable filaments.   Oc-
casionally, however,  a  ganglion, called the maxillary, is
formed here by one or more filaments of the lingual nerve,
and from this ganglion proceed filaments to the submaxilla-
ry gland.
  The lingual nerve then proceeds forwards between the
mylo-hyoideus and the hyo-glossus muscle, and between the
sublingual gland  and the latter,  having in  front of it the
excretory duct of the submaxillary gland.  It anastomoses
frequently with the hypo-glossal nerve, sends several fila-
ments to  the lining  membrane of the  mouth,  below the
tongue, and to the sublingual gland.   It then divides, or
radiates, into seven or eight fasciculi, which run upwards
and forwards on the  side of the  stylo-glossus muscle, and
are finally spent upon the side and the tip of the tongue,
by very fine filaments penetrating into the structure of the
papillae.
  The tensor tympani muscle is  supplied by a nerve called
Auricular  by its discoverer,  Dr. Arnold, coming from  a
ganglion near the foramen ovale formed by filaments from
the inferior maxillary nerva  This  ganglion is below the
spinous process of the sphenoid bone, and sends off several
filaments, one contributes to the  nervous anastomosis of Ja-
cobson, which connects the superior maxillary, glosso-pha-
ryngeal,  and sympathetic nerves: the other filament passes
to the tensor tympani and  is  distributed upon  it.  Other
filaments join the superficial temporal nerve, that part  of it
which supplies the membrana tympani.  There is also an
anastomosis with the portio mollis.*
* Am. Med. Jour. vol. v. p. 192. 
468
NERVOUS SYSTEM.
              SECT. VI.--NERVUS FACIALIS.

   The Facial Nerve (Nervus Facialis; portio dura septi-
 mi; par septimum) having gained the meatus auditorius
 internus, passes in front of the auditory nerve into the canal
 of Fallopius, and winding  through it, around the tympa-
 num, it emerges at the stylo-mastoid foramen, having sent
 in this course one or more filaments to the muscles of the
 little bones of the tympanum.
   Afterwards, the facial  nerve  gives off several branches,
 which are  distributed as follows:
   a.  The posterior auricular nerve arises near the  foramen,
 and having sent several filaments into  the mastoid process,
 it winds over the anterior face of the base of the latter, and
 divides into two fasciculi.  The anterior is distributed in
 filaments upon the back of the external ear, the cartilaginous
 meatus, and the posterior auris muscle; the posterior ascends
 upon the mastoid portion of the temporal bone to the  pos-
 terior belly of the occipito-frontalis muscle, and is  spent by
 filaments to  the latter, and to  the corresponding integu-
 ments, anastomosing likewise  with ramifications of the oc-
 cipital nerve.
   b.  The facial  nerve then  detaches filaments to the  mus-
 cles of the styloid process, and to the posterior belly of the
 digastric muscle.  It also  sends filaments of anastomosis to
 the superior part of the sympathetic nerve; to the cutaneous
 cervical: and to ramifications of the glosso-pharyngeal;  of
the pneumo-gastric, and of the accessory.
  The facial nerve, having given off the foregoing filaments
and branches, penetrates downwards and forwards into the
substance of the parotid gland, where  it is divided into a
number of  branches, varying from two to five, which form
a plexus by their anastomosis.   This plexus is reenforced,
 as mentioned, by branches from the superficial temporal  of
the inferior maxillary,  which wind  around the neck of the
lower jaw.   It is then  distributed to the side of the face  in 
NERVUS FACIALIS.                469
radiating clusters or columns of filaments, called the tempo-
ro-facial, the buccal, and the cervico-facial.
  The Temp'oro-facial Nerves or Branches, are hid for some
distance in the upper part of the parotid gland, which they
traverse  below the  neck of the lower jaw.   They divide
into filaments, some of which go to the temple, and others
to the cheek.  The temporal branches are  commonly two
or three in number; they leave filaments with the parotid
gland, mount over the  zygoma, "and are  distributed to the
anterior auris muscle, to the outer section of the orbicula-
ris palpebrarum, and to the integuments of the temple; they
anastomose in their distribution with each other, with the
superficial and deep temporal branches of the inferior max-
illary nerve, and with the frontal and  lachrymal branches
of the ophthalmic. The malar branches are primitively, also,
two or three in  number; they cross the malar bone, divid-
ing, subdividing, and anastomosing again, and are spent upon
the integuments and muscles of this part of the face.  They
also anastomose with filaments of the lachrymal nerve, and
with those of the infra-orbitar nerve.
  The Buccal Branches are three in number, sometimes two
only; and pass across the masseter muscle under the skin.
The superior anastomoses with  the temporo-facial, and the
inferior with the cervico-facial.   The buccal branches sup-
ply the  skin and muscles of the face intermediate  to the
eye and  to the  lower lip.   The  numerous  filaments into
which they divide anastomose  frequently with each other,
and with the branches of the fifth pair, which appear about
the same  parts,  as the external and  internal nasal  nerve,
the infra-orbitar, and so on.   The middle buccal is parallel
with the duct of the parotid gland and adheres to it.
  The Cervico-facial Branch descends in the substance of
the parotid gland, behind the ramus of the lower jaw; when
it reaches the angle of the latter it goes obliquely forwards,
beneath  the platysma  myoides muscle.  Though it sends
off  many fasciculi, they may be referred to  two divisions,
a superior, and  an inferior.   The  first crosses the inferior
part of  the masseter muscle, and  may be traced in its nu- 
470
NERVOUS SYSTEM.
merous distribution  of filaments,  to the integuments and
muscles  lying upon  the body of the lower jaw.   These
filaments anastomose with each other,  and  with the mental
branches of the inferior dental nerve. The inferior division
supplies the skin and the platysma myoides muscle of the
upper part of the neck along the base of the lower jaw.  Its
filaments are joined by several  coming from the anterior
fasciculus of the third cervical nerve.
   The anastomoses of the facial nerve,  derived from its own
branches and from those of the trigeminus, which reach the
face are entirely too numerous for a detailed description of
them, it indeed appears unnecessary to extend the latter be-
yond  a  certain point.  The  most satisfactory account has
been published by Meckel.*


             SECT. VII.--NERVUS HYPOGLOSSUS.

   The Hypo-glossal  Nerve (Nervus Hypoglossus, Lin-
gualis)  having arisen from the medulla oblongata, and es-
caped from the cranium through the anterior condyloid fo-
ramen, adheres closely for an inch to the  pneumogastric
nerve.   It descends between the external carotid artery and
the internal jugular vein, the Ir.tter being behind  the other,
and then winds over the carotid externally, just below the
origin of the occipital artery.   It is there  covered  by the
posterior belly of the digastricus and by the stylo-hyoideus.
It then passes forwards beneath the external jugular vein,
and lower down somewhat  than the tendon of the digastric
muscle,  and finally ascends  to the  tongue, being covered or
concealed by the mylo-hyoideus muscle.  The nerve in this
course, from the external carotid to the tongue, forms a re-
markable curve, the convexity of which is downwards.
  The Hypo-glossal,  while adhering to the par vagum,
commonly leaves  a  few filaments  with it.   As  it  crosses
the external carotid  it detaches a large branch, the Ramus
Descendens  Noni, which goes down the neck, along the

  * J. F. Meckel, de nervis faciei, Mem. de 1'Acad. des S. de Berlin, 1751
Caldani. Tah. 247- 
NERVUS HYPOGLOSSUS.
471
sheath of the carotid artery and  the  internal jugular vein,
in front of the latter.
  The ramus  descendens has been  beautifully figured by
Scarpa,  in his Plates of  the  Nerves.  According to him,
when it has  got about half way down the  neck, but still
resting on the sheath of the vessels, it detaches in front two
filaments, which, after the course of an inch forwards unite,
and then separate again to be distributed to the upper ends
of the omo-hyoid and sterno-hyoid muscles.  The descen-
dens noni then forms, an inch lower down, a small gangli-
form  plexus, resting  upon the sheath of the great vessels
of the  neck, under  the  omo-hyoid  muscle.   This plexus
is joined by two fasciculi, which descend from the first and
second cervical nerves, and from it proceed downwards and
backwards, two filaments,  which join the phrenic nerve;
also one to the lower part of the omo-hyoid  muscle; and
three or more, which are divided and distributed  upon the
sterno-hyoid and thyroid muscles, and upon the muscles of
the larynx.   Meckel states, that some of these  ramifica-
tions, on the left side principally, penetrate to the thorax,
and reach the pericardium.
  The hypo-glossal nerve, having sent off the ramus descen-
dens, reaches  the external face of the hyo-glossus muscle,
and is there concealed by the mylo-hyoideus, where it gives
filaments to the muscles  of the larynx, to the hyo-glossus,
genio-hyoideus, and  genio-hyoglossus.    These  filaments
anastomose frequently with each other, and in two or three
places at the anterior part of the tongue with a lingual branch
of the nervus trigeminus.   After these branches  are given
off, the trunk  of the hypo-glossal nerve penetrates into the
substance of the genio-hyo-glossus muscle,  and extends it-
self near its fellow,  and not far from  the middle line of
the tongue to the point of the latter.   It first distributes fila-
ments near the posterior part of the tongue, and  then suc-
cessively as far as its anterior extremity.   They cannot be
traced to the  papillae but are lost upon the muscular struc-
ture.
   It  is a general opinion among anatomists that  the hypo-
 glossal nerve is only intended to excite the muscular move- 
472
NERVOUS SYSTEM.
ments of the tongue.  The opinion is founded upon the cir-
cumstance of its filaments not reaching the papillae, whereas
those of the lingual branch of the trigeminus do.   Colombo
narrates a case, in which there was a congenital privation of
taste, where the lingual  branch of the trigeminus  was dis-
tributed upon the occiput instead of upon the tongue, which
goes  far to prove  the  difference of function in  the two
nerves.

            SECT. VIII.--NERVUS ACCESSORIUS.

  The Accessory  Nerve (Nervus  Accessorius,  Willisii)
having arisen, as described,  from the cervical medulla and
the medulla oblongata, is directed outwards to the posterior
foramen  lacerum, in company with the pneumo-gastric or
par vagum.   Sometimes it is separated from it in its passage
through the base of the  cranium, by a thin partition of dura
mater, on other occasions merely by  a  fold of the tunica
arachnoidea, but at the  inferior part of this foramen it ad-
heres so closely to the par vagum that the two look like but
one nerve.
  Near its exit it is divided  into two  fasciculi.   The most
internal gives off one or two filaments, which, joining a
branch of the par vagum, forms the superior pharyngeal
nerve; the internal branch then descends, and being divided
into several  branches, they successively join the upper part
of the par vagum.   The external  fasciculus  descends for
two inches behind  the internal jugular vein, being placed
first of all between it and the occipital  artery, but subse-
quently between the vein and the  sterno-mastoid muscle.
It then pierces the muscle about one-third of the length of
the latter from its superior extremity, and leaves filaments
in it which anastomose with some from the third cervical
nerve.  In continuing its descent it is re-enforced and aug-
mented considerably in  volume by branches from the  se-
cond and third cervical.   Having reached the anterior mar-
gin of the trapezius muscle,  it then distributes itself to the
latter, by internal and by external branches. 
GLOSSO-PHARYNGEAL NERVE.
473
        SECT. IX.--NERVUS GLOSSO-PHARYNGEUS.

  The Glosso-Pharyngeal Nerve (Nervus Glosso-Pharyn-
geus,) though commonly considered  as  distinct from  the
pneumo-gastric, has so many connexions with it, both at its
root, in its course through the posterior  foramen lacerum,
and in its distribution, that it seems like a part or branch of
the same.   Before it enters the canal of the dura  mater,
which conducts it through the base of the cranium in front
of the pneumo-gastric, it forms, according to some anato-
mists,* a ganglion of  five or six  lines in  length, the exist-
ence of which is  denied  by Bichat.  From this ganglion
proceeds a filamentt which penetrates into  the tympanum,
and divides into two branches; one of them ascends along
the promontory, having detached a filament to the membrane
of the foramen rotundum; it then penetrates the  petrous
bone; and anastomoses or joins with the superficial  petrous
nerve.  The other branch passes below the bony Eustachian
Tube, and gaining the carotid canal anastomoses there with
the Sympathetic Nerve.   The ganglion also gives off other
filaments, which traverse the canal of the dura mater, to
join the pneumo-gastric nerve, the accessory and the sym-
pathetic.
  On issuing from the  posterior foramen lacerum, the glosso-
pharyngeal is separated from the pneumo-gastric by the in-
ternal  jugular vein.  It  is  then directed downwards and
forwards between the internal  carotid and the stylo-pha-
ryngeus muscle;  afterwards between  the  latter and  the
stylo-glossus; it follows  the direction of the latter to  the
side of the root of the tongue.
  In this course it sends off  many filaments. Shortly after
leaving the cranium it detaches one backwards to the digas-
tric branch of  the facial, and another to  the pneumo-gas-
tric.   It then sends off two filaments, which descend along

                  * Andersech and Huber.
                  | Rosenmuller, Jacobson, Lobstein.
  Vol. 11.—60 
474
NERVOUS SYSTEM.
the internal and  the common carotid, and are divided into
several branches, some of which anastomose with the pha-
ryngeal branch of the pneumo-gastric, others descend on the
common carotid with filaments from the pharyngeal branch,
and being joined by two or three small twigs from the supe-
rior cervical ganglion, they reach the lower part of the neck,
and concur in the forming of the superficial cardiac nerve.
Further down after the origin  of these branches the glosso-
pharyngeal detaches two  or three  filaments to  the  stylo-
pharyngeus muscle, as well as some to the upper and middle
constrictors of the pharynx, to  the pharyngeal plexus of the
sympathetic and pneumo-gastric, and to the posterior lateral
and superficial part of the  tongue.
  The glosso-pharyngeal  nerve having got between the
stylo and  hyo-glossus muscles, is placed intermediately to
the lingual branch  of the fifth pair and  the hypo-glossal
nerve. Some of its branches then go to the integuments of
the base of the tongue, to its mucous glands, large papillae,
and may be traced to the mucous membrane of the soft pa-
late, to the amygdalae, and to the covering membrane of the
epiglottis.  Others  go into the muscles of the tongue, and
others may  be  traced  along  the  external margin of the
tongue, beneath its mucous membrane for some distance.
Scarpa has delineated a remarkable plexus, which he deno-
minates  Circulus Tonsillaris  Anderschii or Anastomosis
Plexuosa, formed by these several filaments and by branches
of the lingual, on the side of the root of the tongue, at the
base of the tonsil gland.


          SECT. X.--NERVUS PNEUMO-GASTRICUS.

   The Pneumo-gastric Nerve  (Nervus Pneumogastricus,
 Vagus, Par Octavum, Decimum of Andersech) at its exit
from the cranium  through the posterior foramen lacerum,
 in front of the internal jugular vein, is closely united to the
hypo-glossal, glosso-pharyngeal, and accessory nerves,  by
 compact cellular substance.  It is first placed in front of the
hypo-glossal  nerve, but in a short space gets behind it, and 
PNEUMO-GASTRIC NERVE.
475
is also separated from the glosso-pharyngeal by the internal
jugular vein.  Opposite the transverse process of the atlas,
it leaves the hypo-glossal nerve, and assumes a position be-
tween the internal  carotid and the internal jugular, on the
vertebral side of these vessels, and is enveloped in their
sheath of dense cellular substance.  It maintains this relative
position  along the common carotid to the root of the neck.
   At the latter  place  the  pneumo-gastric of the right side
goes in front of the subclavian artery near its root, but on the
left side  it crosses the root of the left subclavian artery, and
the arch of the aorta to the left of the origin of the left ca-
rotid.   In getting  fairly into the cavity of the thorax, it
is directed backwards and downwards from  these points,
towards  the posterior  face of the  bronchia, between it and
the pleura.  It then abandons the bronchia, and applies itself
to the oesophagus,  and follows  it through  the diaphragm
to the stomach.   The  nerve of the left side,  in its course
along the oesophagus, is on the front surface of the latter,
and the nerve of the right side on its posterior surface.
   The pneumo-gastric anastomoses with the accessory while
passing through the foramen lacerum  posterius.  Somewhat
lower down, it also anastomoses with the glosso-pharyngeal
and with the superior  cervical ganglion of the sympathetic.
The branches which it afterwards  sends off,  go to the neck,
to the viscera of the thorax, and to those of the abdomen,
after the following  manner:

   A. Cervical Branches. The  Superior Pharyngeal Nerve
(Ramus Pharyngeus) arises just below the preceding anas-
tomosis.   It is directed downwards on the  internal face of
the internal carotid, and having sent an anastomotic filament
to the glosso-pharyngeal nerve, it forms on the middle con-
strictor of the pharynx, the pharyngeal plexus which is re-
enforced by filaments  from the superior  cervical ganglion
of the sympathetic, from the glosso-pharyngeal, and from
the superior laryngeal  nerve. The  filaments departing from
this plexus, are spent principally upon the middle constrictor.
but a few of them also go  to the superior constrictor; and
others, descending along the primitive carotid, anastomose 
476
NERVOUS SYSTEM.
with ramifications from the glosso-pharyngeal, and from the
superficial  cardiac nerve.  A filament, called  the inferior
pharyngeal, sometimes proceeds from the pneumo-gastric a
little below the other, and also is spent upon the pharynx.
  The pneumo-gastric, at the place where it detaches these
pharyngeal branches, or  a little above them, becomes soft-
ened in its texture, enlarges  somewhat, and has the fasciculi
which compose it, moderately separated by a sort of red
gelatinous  substance interposed between them. This por-
tion is  its gangliform  plexus, and into it is joined one or
more branches from the accessory nerve.
  The Superior Laryngeal Nerve (Ne?*vus Laryngeus Su-
perior) arises from the gangliform plexus.  It  descends be-
tween the internal carotid and the superior cervical ganglion,
anastomosing on the way with the latter, with the pharyn-
geal plexus, and the hypo-glossal nerve; it then divides into
an external and  an internal  laryngeal branch.  The former
sends its filaments to the muscles situated on  the fore part
of the thyroid cartilage;  to the thyroid gland; and some of
them  penetrate through the  crico-thyroid  membrane to the
lining membrane  of the larynx.  The internal  laryngeal
branch is placed above the other; it is directed towards the
thyreo-hyoid membrane, which it penetrates and then begins
to ramify.   Some of the branches go to the epiglottis carti-
lage, its covering  membrane, and the adjacent  portion of
the lining membrane of  the pharynx. Other  branches are
distributed to the  small muscles which move the arytenoid
cartilages, and to the lining  membrane of the larynx.   The
filaments which go  to the epiglottis have an  arrangement
indicated by Bichat; that of  going into the foramina which
perforate it, but  they cannot be traced further.
  The pneumo-gastric afterwards does not send off any re-
gular branches till it reaches the lower part of  the neck. It
then detaches two or three filaments, (rami cardiaci) which,
on the right side, have their  roots about an inch  above the
subclavian artery, and on  the left side, an inch lower down.
On the right side they descend along the subclavian and the
arteria innominata, on the left along the left carotid;  they 
PNEUMO-GASTRIC NERVE.
477
reach the arch of the aorta, and in their course, as well as
there,  anastomose very freely with the superficial cardiac
nerve.  The rami cardiaci are frequently more abundant on
the right side than on the left.
   The Inferior Laryngeal Nerve (Nervus Laryngeus In-
ferior, Recurrens) is a considerable branch of the pneumo-
gastric, which comes off next to the cardiac.  On  the right
side it arises immediately after the  trunk has passed be-
tween  the subclavian  artery and  the subclavian  vein.  It
then winds around the subclavian  artery so as to retain the
latter in its loop; having thus got behind the artery, it then
ascends towards the larynx  on the side of the trachea, co-
vered  by the common carotid and by the  inferior laryngeal
artery.
   In this course the inferior laryngeal  nerve detaches the
following branches:  1. From the convexity of its loop  it
sends filaments to the assistance of the cardiac branches just
spoken of,  arising^ from the pneumo-gastric, and  to those
coming from the  inferior cervical ganglion of the sympa-
thetic.  2.  It detaches the pulmonary branches, the origin
of which  is complicated  with the plexus of nerves ex-
isting  about their roots;  these descend  in front of the tra-
chea, reach the pulmonary  artery, and  follow its ramifica-
tions into the lungs; some of the filaments, however, go to
the cardiac plexus.  3. The inferior pharyngeal then sends
many  filaments to the  oesophagus; 4. Branches which go to
the inferior part of the thyroid gland;  5. Filaments to the
trachea,  some  of which penetrate  the membrane on its
posterior  part, others go between the  cartilages; they are
then distributed to the lining membrane and to the mucous
glands of the part.   6. The inferior laryngeal nerve is then
distributed in  branches  to  the inferior constrictor of the
pharynx and its lining membrane; but  the most of its ter-
minating filaments penetrate to the larynx between the thy-
roid and the cricoid cartilage, and are lost upon the lining
membrane of the larynx, and upon the small muscles which
move the arytenoid cartilages. These terminating filaments 
478
NERVOUS SYSTEM-
 anastomose with such as come  from the superior laryngeal
 nerve.
   It is generally stated by anatomists that the distribution
 of the recurrent laryngeal nerve to the larynx, is confined
 to the thyreo-arytenoid, crico-arytenoid, posterior and late-
 ral muscles.  Mr. G. Rainy, states in the London Medical
 Gazette, that he has repeatedly traced its filaments also, to
 the transverse and oblique arytenoid.*  The recurrent of
 the left side forms a much larger  loop than the other, and
 arises lower down, inasmuch as it has to wind around the
 arch of the aorta, at the origin of the left subclavian artery;
 with some inconsiderable exceptions, its course and distri-
 bution afterwards are precisely the same with those of the
 nerve of the right side.

   B.  The Thoracic Branches of the pneumo-gastric are as
 follow: The inferior tracheal  nerves come from it just be-
 low the recurrent;  they are five or six in number; some of
 them go in  front of the  trachea and bronchia, and  others
 behind  them.  They are complicated by anastomoses with
 the branches of the recurrent nerve,  and with those of the
 inferior cervical ganglion, and  form  a small plexus, deno-
 minated the anterior pulmonary, which lies upon  the front
 of the root of the lung, and has its filaments following the
 branches of the pulmonary artery  through the lung.  The
 posterior filaments supply the structure of the bronchia by
 penetrating  it, and some of them go  to join  the  posterior
 pulmonary plexus.
   As the pneumo-gastric gets behind the trachea and the
 bronchia, it is  sensibly enlarged and somewhat flattened,
 the cohesion of its fasciculi being somewhat looser.  Seve-
ral filaments depart there from  it,  which form an intertex-
ture with each other;  some of them pass inwards,  to be dis-
tributed on the bronchia, trachea, and oesophagus.   Others,
which are given off as the nerve lies upon the posterior face
of the root of the lung, amounting to six or seven  in num-

            * Am. Med. Journal, Vol. iv. p. 198 
PNEUMO-GASTRIC NERVE-
479
ber, but being of various sizes; run transversely outwards,
and form an intertexture with one another: The latter are
joined by filaments from the inferior cervical and the first
dorsal ganglion of the sympathetic, and thus constitute the
posterior pulmonary plexus. The filaments from this plexus
follow the distribution of the bronchia; and according to Bi-
chat, are all destined to the mucous membrane and the mu-
cous glands of the lung; as  they may be traced piercing suc-
cessively the ramifications  of the bronchia, in order to reach
its  lining membrane.
  On the right side, the par vagum,  while furnishing the
pulmonary plexus, and for some distance lower down, is
divided into from four to  six considerable fasciculi, which
form with each  other a plexus or  series  of anastomoses
having very large meshes, and  from which proceed many
filaments to the oesophagus.  Afterwards these fasciculi are
assembled into a single chord, which proceeds on the pos-
terior face  of the  oesophagus, along with  it into  the ab-
domen.
   On the left side, the par vagum,  after forming the pos-
terior pulmonary plexus, is split into  two or three fasciculi;
 which  likewise  furnish branches to the  oesophagus; and
 unite to form a single chord, which  proceeds on the front
 surface of the oesophagus,  along with it into the abdomen.
    The two nerves while descending  in this way, send fre-
 quent anastomotic filaments to each  other, and to the oeso-
 phagus.

    C. In the Abdomen the par  vagum is distributed as fol-
 lows: Filaments are  sent  from  each, which form a plex-
 us  around the cardiac orifice of the stomach.   The right
 nerve is then divided into many branches; some are distri-
 buted on the posterior face of the stomach; others go along
 the lesser curvature of this viscus, and reach thereby the
 pylorus,  where  they anastomose with filaments from  the
 left nerve, and from the gastric plexus of  the sympathetic;
 others go behind the stomach to join the solar plexus, and
 are blended with the latter  in its distribution to the liver, 
480                NERVOUS SYSTEM.

vena portarum, duodeum, and  pancreas.  The left par va-
gum being placed in front of the cardia,  is resolved into
several radiating filaments or fasciculi, some of which sup-
ply the anterior face of the stomach, others  go along its
lesser curvature to the pylorus, to anastomose with the
right nerve and the gastric branches of the sympathetic,
and are finally blended, after the same  manner as the pre-
ceding, with the solar plexus.
                     CHAPTER II.

             OF THE SYMPATHETIC NERVE.*

  The Sympathetic Nerve (Nervus Sympatheticus Mag-
nus, Intercostalis Maximus, Gangliosus,) differs, in a
great number of  respects,  from every other nerve of the
body; and, if we were actuated only by its peculiarities, with
Bichat, Meckel, and others, we might with  great proprie-
ty,  set it apart as something having  a claim to an insulated
description and location.   The dissection of it,  however,
is so much blended with that of  the par vagum, that the
descriptions of the two, go  best hand  in hand; and are
therefore most conveniently studied  together.
  This nerve  consists in a series or chain of ganglions, ex-
tending from the  base of the  cranium to the lower end of
the sacrum.   They are  placed on the lateral part of the bo-
dies of the vertebrae, are united to each other by interme-
diate nervous  chords, and send off continually filaments to
the adjacent organs.    With  the exception  of  the neck,
there is a ganglion for each intervertebral space, both of the
true vertebrae  and sacrum.  Besides these ganglions, there
are  others which are situated around the  trunks of some of
the large vessels of the  abdomen.
  The superior extremity of the sympathetic nerve, oppo-
* Anton. Scarpa, Tabul. Neurolog. 
THE SYMPATHETIC NERVE.
481
site to the transverse  process of the  second cervical verte
bra, and behind the internal carotid artery, forms a ganglion,
which for the purpose of description, may be considered as
the first of the  series.  This ganglion is the superior cer-
vical. The nervus motor externus opuli in passing through
the cavernous sinus, and the vidian nerve in passing by the
point of the petrous bone, both  send a filament downwards
through the carotid  canal; which two  filaments unite to
form a single chord,  that  runs  into the superior extremity
of this ganglion.  The filament from  the vidian nerve  is,
as mentioned, the deep petrous nerve.   The common view
taken by anatomists of this nervous connexion is, that it is
the beginning of the sympathetic, though by Bichat it is de-
scribed as the termination, or one of its extremities.   The
distinction,  though important  physiologically,  is less  so
when the object is simply to describe the course and anato-
mical relations of this nerve, as  they may be equally under-
stood by either mode  of description.
  The branch from  the  motor externus most frequently
forms, on the external face of  the internal carotid, in the
cavernous sinus, a ganglion, (Ganglion Cavernosum) dis-
covered by Laumonier, which  is sometimes made by seve-
ral filaments from the motor externus instead of one.   Mr.
Lobstein,in his Essay on the Sympathetic, has attributed this
ganglion to the deep  petrous nerve, in which I think he is
mistaken.   From the ganglion  cavernosum, it has, of late,
been ascertained that filaments may be traced to the Gangli-
on of Gasser, (Plexus Gangliformis,) of the trigeminus, to
the pituitary gland,  to the infundibulum; and, moreover, a
fasciculus which, according to H. Cloquet,  forms a plexus
around the ophthalmic artery, and may be  traced along all
its branches, even the central artery of the  retina.  This
plexus anastomoses with the lenticular  ganglion, and con-
sequently establishes  a direct nervous communication  be-
tween the sympathetic, the motor oculi, and first branch
of the fifth pair.  The knowledge of this  connexion has
caused anatomists to   locate the lenticular ganglion and the
ciliary nerves  in the  ganglionic system of the sympathe-
tic, as forming a part of the latter.
   Vol.  II.— 61 
482
NERVOUS SYSTEM.
  The sympathetic, in descending the neck, is placed behind
the carotid artery and internal jugular vein.   It is commonly
said to be enclosed in the sheath of these great vessels, but
the statement is loose and inaccurate, as it is fastened to the
front surface of the longus colli muscle by cellular substance
distinct from the sheath, as  may be manifested by pushing
a knife handle between them and raising up the sheath. The
chord which  comes down from the carotid  canal is close
to  the  pneumo-gastric and hypoglossal nerves.  Having
formed the first cervical ganglion, it descends as mentioned;
and, opposite to the  space between  the  fifth and the sixth
cervical vertebra, it  is again enlarged into  the Middle Cer-
vical Ganglion, which is much smaller and  more irregular
than the first.  The sympathetic is then traced with some
difficulty, in consequence of the numerous branches coming
from it; but, with attention, a  trunk may be  found  as the
continuation of it. This trunk passes to the interval between
the head of the first rib and the transverse process  of the
last cervical vertebra, and there enlarges into another gan-
glion, called Inferior Cervical, or First Dorsal.

  To understand well the connexions of the sympathetic  in
the neck, each of the  cervical ganglions must  be  studied
particularly.

  1st. The  Superior Cervical Ganglion varies considera-
bly in its extent; commencing very generally opposite  to
the second cervical vertebra, it is sometimes elongated to the
lower part of the third and even of the fourth.   In cases  of
unusual elongation, it is smaller than in others.
  It sends off, from its external margin, several filaments,
about four, which cross the anterior face of the rectus anticus
major muscle, and terminate  by anastomosing with the ante-
rior fasciculi of the occipital nerve and of the three first cervi-
cal; when the ganglion is short, the two lower filaments come
from the sympathetic below it, instead of from the ganglion.
  Several filaments also proceed from  this  ganglion  to the
contiguous muscles on the vertebral column, to the pharynx,
to the larynx, and to the thyroid gland. 
THE SYMPATHETIC NERVE
4S3
  This ganglion also sends off what are called its Anterior
branches, which are peculiar for  their reddish colour and
for their  softness; the latter quality has obtained for  them
the name of Nervi Molles.   They may be referred, by their
position, to three orders.   The  superior ascend to anasto-
mose with the pneumo-gastric, hypoglossal, and facial nerves,
near their exit from the  cranium.  The middle are two or
three in number, but immediately divide into many filaments,
forming the carotid plexus by assistance from the pneumo-
gastric, glosso-pharyngeal, and facial nerves.   Some of the
branches of this plexus descend behind the primitive caro-
tid, at the place of  its  bifurcation, and accompany it to its
origin, continually interlacing with each other.  Others sur-
round, after the same manner, the external carotid, and sub-
divide into a plexus for each of its branches, so that very
fine filaments may be traced along the superior thyroidal,
the lingual, facial, occipital, and temporal  arteries.   These
nerves are, for the most part, difficult to trace,  from their
extreme tenuity.  The primitive  branches, from which these
plexuses come, are sometimes previously united into a small
ganglion, which serves as a common centre to all these ner-
vous irradiations.   The  third order  of anterior  branches,
amounting to from  four to six, come  either from the gan-
glion or  from the sympathetic just  below it.   The  chord
formed by their union, called the Superficial Cardiac Nerve,
descends on the external side of the primitive carotid, anas-
tomosing with filaments from the pneumo-gastric and from
the descendens noni.  It gives small ramifications to the con-
tiguous parts, as to the pharynx, oesophagus,  the sterno-hy-
oid and thyroid muscles.  It terminates in the lower part
of the neck,  by detaching anastomosing  branches to  the
branches of the recurrent nerve; some of them also go along
the inferior thyroid artery to the thyroid gland.   What re-
mains of it  is lost in the middle cardiac nerve, for it can-
not be traced,  in an  insulated and distinct manner, to the
heart; from which cause, its appellation is objectionable.

  2.  The Middle Cervical Ganglion, placed intermediate- 
484
NERVOUS SYSTEM.
 ly to the fifth and sixth cervical vertebra, upon the longus
 colli muscle, is there concealed by the common carotid, the
 internal jugul r vein, and the pneumo-gastric nerve.   It is
 sometimes deficient: according to Meckel, in the proportion
 of once in three times.  In my own dissections I have  al-
 ways found it, though under various circumstances of size
 and form.   It is more flattened than the preceding, and ne-
 ver so long.   Sometimes it is double. Like the preceding,
 it  has a  great many filaments attached to,  or emanating
 from it.
   The external filaments, amounting to about three in num-
 ber, pass from it to the anterior fasciculi of the fourth, fifth,
 and sixth  cervical nerves, between the origins of the sca-
 leni muscles.   Some  of its filaments accompany the infe-
 rior thyroid  artery, and, along with  the  superficial car-
 diac, form a plexus around it, which reaches to the thyroid
 gland.
   The Middle Cardiac Nerve is formed by several of the
 anterior branches, collecting into a single chord.   The lat-
 ter descends along the external side of the  primitive caro-
 tid, crosses, on the right side of the body,  the root of  the
 subclavian artery, and then,  going along the posterior face
 of the arteria innominata, it gets between the aorta and the
 bifurcation of the trachea, where it is merged in the com-
 mencement of the cadiac plexus of nerves.  On the left side,
 the middle cardiac nerve is formed by an assemblage of fila-
 ments from the middle and inferior cervical ganglions, which
 descend along the left subclavian artery to the aorta, and are
 joined, on the front of the latter,  by the superficial cardiac
 nerve.  On both sides, these  cardiac nerves form intricate
 anastomoses with the pneumo-gastric nerve and its recurrent
 branch.

  3. The Inferior  Cervical Ganglion, situated  as  men-
 tioned, near the head of the first rib, like the others, is sub-
ject to variations in  its form  and  size.   Several  filaments
 may be traced between it and  the middle cervical ganglion.
 One penetrates  into the canal of the transverse processes 
THE SYMPATHETIC NERVE.
485
along with  the  vertebral artery, and, forming  a  plexus
around it, may be traced distributing branches to the heads
of the contiguous muscles, as  high up as the second cervi-
cal vertebra.
  The external branches of the inferior cervical ganglion
are numerous and small.  Some of them anastomose with
the anterior fasciculi of the two or three inferior cervical
and the first dorsal  nerve.  Others form a  plexus  around
the subclavian artery, and follow the latter,  in its distribu-
tion, to the upper extremity and to the shoulder.
  The anterior branches of this ganglion concur, after some
anastomoses with each other, to form a  single chord,  the In-
ferior Cardiac Nerve, which goes, on the right side, along
the arteria  innominata, to  be blended with the  cardiac
plexus.   On the  left side, it is not so distinct, but is blend-
ed with the middle cardiac nerve, and forms its inferior root.


      Of the Cardiac Plexus of the Sympathetic.

  The Cardiac Plexus (Plexus Cardiacus) is situated be-
tween the arch of the aorta, and the lower part of  the tra-
chea and  the  bronchiae, and extends  from the division of
the pulmonary artery to the commencement of the  arteria
innominata.  It is formed almost wholly from the branches
sent by  the three cervical ganglions of the sympathetic, and
principally from that of the  middle one, or the middle car-
diac  nerve.   The filaments which come from the  recurrent
nerve and the par vagum are blended into the cardiac plexus
in such  a manner that they cannot be traced immediately to
the heart.   It is  worthy of  remark, that  the three  cardiac
nerves of the  right  side  are  more constantly found than
the same  number on the left,  in consequence of the lower
one of the latter  soon merging itself, after its origin, into
the middle cardiac nerve of  that side.
  The cardiac plexus is formed by the  common assemblage
of the nerves from the two sides of the neck, and is there-
fore single.   From this plexus arise all the  nerves which
go to the heart, so that in tracing them the distinction be- 
486
NERVOUS SYSTEM.
tween right and left is confounded.  Scarpa has pointed out,
in this  circumstance, an  analogy between them and the
nerves which supply  the abdominal viscera.
  The cardiac plexus is distinguished by the softness of its
texture.   For the purpose of description, its branches may
be divided into Anterior,  Posterior, and Inferior.
  The Anterior  Branches are but few.   They are found
on the front of the arch of the aorta.  One of them crosses
it on the right side of the arteria innominata; others cross it
from the root of the left carotid and subclavian downwards.
In both cases, several of the terminating filaments run into
the anterior coronary plexus.*
  The  Posterior Branches are more  numerous, but run
only a short course, when they are merged in the anterior
pulmonary plexus formed by the par vagum.
  The Inferior Branches are the largest and the  most abun-
dant.   Some of them follow the pulmonary artery until its
entrance into the lungs, others are distributed upon the pul-
monary veins, but the greater number of them are arranged
into two plexuses called Coronary, from their observing the
course of the coronary arteries.   The  posterior coronary
plexus is larger than the other.   It reaches the base of the
heart, along the left pulmonary artery, and has its filaments
distributed principally to  the left auricle and the left ventri-
cle, observing the course of the left coronary artery and  of
its branches.  The anterior coronary plexus gets in front of
the heart, between the aorta and the pulmonary artery.   It
anastomoses freely at its superior part with the  other, and
is then distributed to  the  right auricle and ventricle, along
the course of the right coronary artery and of its branches.


     Of the Thoracic Ganglions of the Sympathetic.

   These ganglions are twelve in number, and are placed on
or near the heads of the ribs, at the commencement of each
intercostal space, and  are only  covered by  the pleura.
* Scarpa. 
THE SYMPATHETIC NERVE.
487
 Their shape is irregular, and they differ also in size, being
 always smaller than the cervical ganglions.   The chord of
 the sympathetic is continued successively from one ganglion
 to another, so that they form a complete chain by their con-
 nexion with each other.
   From each ganglion there proceeds  one or more  exter-
 nal branches, which go  outwards to anastomose with the in-
 tercostal nerve of the corresponding part.   Each ganglion
 also detaches one or more internal branches  or  filaments
 to the adjacent parts lying on the  vertebral column: some
 go to the cellular substance, others to  the longus colli mus-
 cle,  others to the aorta,  others to the cardiac and to the pul-
 monary  plexuses.   Among these internal branches there
 are several which concur to form the Splanchnic Nerves, of
 which there are two: the Great and the Small.

   The Great Splanchnic Nerve arises, by filaments, from
 the sixth to the ninth or tenth thoracic ganglions inclusive-
 ly; one or more filaments coming from each ganglion.  They
 are directed downwards and forwards on  the sides of the
 dorsal vertebrae, covered by the pleura, and  unite succes-
 sively into a trunk about the  eleventh  dorsal  vertebra.
 This trunk penetrates into the cavity of the abdomen, be-
 tween the middle and the  internal head of the lesser mus-
 cle of the diaphragm, and sometimes by the opening for the
 aorta.
   Having got into the  abdomen, the  great splanchnic di-
 vides into  several fasciculi,  which, diverging from each
 other, are concealed on the right side  by the  liver and on
 the left by the stomach.  On each  side of the aorta, there
 is a large  ganglion formed by  an assemblage of several
 smaller ones; it is called the Semilunar.  Into it terminate,
 for the most part, these fasciculi; some of  them, however,
 go immediately into the solar plexus, which emanates from
 the semilunar ganglion.

   The Small Splanchnic Nerve is derived, by filaments,
from the tenth and the eleventh thoracic ganglions.  Having 
488
NERVOUS SYSTEM.
united, they penetrate the crus of the diaphragm, and reach-
ing the abdomen, the trunk is divided into two branches, of
which the uppermost  ascends to join  the great splanchnic
before its division, and the lower descends to join the re-
nal plexus.
   Besides these two splanchnic nerves, it frequently hap-
pens that there are others which come from  the  eleventh
and twelfth thoracic ganglions, and from the communicating
branch between the last thoracic and the first lumbar. They
unite into a trunk which  goes to the renal plexus, and have
been called,  by Walter, the Posterior Renal Nerves.


                 Of the Solar Plexus.

   The Semilunar Ganglion,  situated, as mentioned, on the
side of the aorta, is somewhat semicircular or oval, and is
about an  inch long;  its form, however, is much diversified
in different subjects.   The several ganglions of  which it is
composed, are frequently fused into a single one.  That of
the right side is  more voluminous  than the  other, and is
placed between the ascending vena cava and the crus of the
diaphragm, somewhat above the right renal artery.   That
of the left is situated upon the left crus of the diaphragm,
somewhat below the splenic artery.   Between  their infe-
rior extremities, there are generally two or three smaller
ganglions.
   These several  ganglions  are united by numerous  fila-
ments, which  send out many ramifications and anastomose
freely with each other.
   The preceding arrangement may be considered as the root
of the solar plexus, which extends from the coeliac artery
to the lower margin of the emulgents, and as  it is common
to the ganglions of the two  sides, it is an inch and a half
or two inches  wide.   Bichat has very properly remarked,
that this  plexus seems to  exist for  the aorta,  as all the di-
visions which  it sends out follow so exactly the  branches of
this artery, that we are forced to adopt the latter as the ba-
sis of the description.  The intertexture and the number 
THE SYMPATHETIC NERVE.            489
of the branches emanating from the solar plexus are so com-
plicated, that  a description of individual branches would
be almost endless, as well as unintelligible; anatomists are,
therefore, generally agreed to describe the  plexus accord-
ing to the order of the arteries which  its detachments ad-
here to and surround.

   1. The Diaphragmatic Plexus consists  of a few fila-
ments coming from the superior part of the  solar, and  fol-
lowing the course of the phrenic arteries.   Some of them
anastomose with  the terminating filaments of the phrenic
nerve, in the  thickness of the diaphragm.

   2. The Plexus which surrounds the Coeliac Artery, like
it, is quickly disposed into three divisions, which follow the
branches of this artery.

   a. The Superior Coronary Plexus of the  stomach, is
the smallest of the three.   It attends the corresponding ar-
tery along  the lesser curvature of the stomach to the py-
lorus, supplying the stomach continually with very fine fila-
ments.   In its course, it anastomoses with the par vagum,
and sends filaments to  the hepatic plexus.

   b. The Hepatic Plexus is the largest of  the three.   It
surrounds the hepatic artery and the vena portarum, and in
its course detaches branches which go with the right gastro-
epiploic artery to the great curvature of the  stomach, and
constitute the  inferior coronary plexus.   Branches are also
sent to the pancreas and to the  duodenum.   The hepatic
plexus then enters the transverse fissure of the liver, and
its branches may be  traced to the several lobes and to the
gall-bladder.

   c. The Splenic Plexus is  but small, and surrounds the
splenic artery.   The few branches of which it is composed,
anastomose but rarely with each other.   Some of them are
distributed  upon the pancreas, along with the pancreatic
   Vol. II.—62 
49 U
NERVOUS SYSTEM.
branches of the splenic artery;  others go with the left gas-
troepiploic artery to the  left extremity and to the greater
curvature of the stomach; the remainder  penetrate into
the substance of the spleen, through its fissure, along with
the branches of the splenic artery.

  3. The Superior Mesenteric Plexus is derived from the
solar, near the superior mesenteric artery; it descends some
short distance on the aorta, before it reaches the latter.  It
descends with the artery between the pancreas and the duo-
denum, and is then included  between the two laminae of
mesentery; it is then distributed,  by very numerous fila-
ments, along with the branches of the artery, to the whole
of the small intestines, to the coecum, and to the  ascending
and transverse colon.

  4. The Renal Plexus, one on each side, is derived from
the lower lateral part of  the solar.  Two  or three gan-
glions, on the root of the renal artery, contribute to it, and it
is also re-enforced by an addition from the lesser splanchnic
nerve.   The branches which form this plexus do not anas-
tomose much, till they get near the kidney; they then pe-
netrate into its substance,  through the  fissure.   Some fila-
ments from this plexus go to  the capsulae  renales: others
follow the course of the spermatic artery, and constitute the
spermatic plexus which goes to the testicle in the  male, and
to the ovarium in the female.

   5.  The  Inferior Mesenteric Plexus is a  continuation of
the solar, on the anterior  face of the abdominal aorta. It is
much smaller than the superior mesenteric  plexus, though
it receives continually, in its  descent, filaments from the
lumbar ganglions of the  sympathetic.   It  forms frequent
anastomoses around the root of the  inferior  mesenteric ar-
tery and near the superior strait of the pelvis, is resolved
into two columns of fibres.  One column is distributed along
with the artery to the rectum, to the sigmoid flexure of the
colon, and to the left section of the latter,  thereby anasto- 
THE SYMPATHETIC NERVE.
491
 mosing with the colic branches of the superior mesenteric
 plexus.  The other column descends into the pelvis in front
 of the  sacrum, and  contributes  to form  the  hypogastric
 plexus, but several of its branches also follow the  external
 and the internal iliac arteries.


     Of the Lumbar Ganglions of the Sympathetic.

   These ganglions are five in number, on  either  side, and
 are placed anteriorly on the sides of the bodies of the lum-
 bar vertebrae, near the anterior margin of the psoas magnus
 mdscle.   Their form is irregular; they are smaller than the
 cervical ganglions, but larger than the dorsal.
   The last thoracic ganglion  is united to the first lumbar by
 a small branch, which maybe considered as the continuation
 of the sympathetic.   A deficiency of this branch has,  how-
 ever, been several times observed  by anatomists; also a de-
 ficiency in the connecting nervous  chord of the ganglions
 below.  The ganglions themselves are inconstant in their
 number, being sometimes less than  five; they vary like-
 wise in their situation.   It is to  be understood, however,
 that in a majority  of subjects, the sympathetic goes on un-
 interruptedly from one ganglion to another, sometimes by
 one  branch, on other occasions  by two or three.
   Each lumbar ganglion sends outwards one, or more exter-
 nal branches, which applying themselves to the body of the
 contiguous vertebra, reach the corresponding intervertebral
 foramen of the loins, and join with the anterior branch of
 the corresponding  lumbar nerve.   Some of these external
 branches are spent upon the quadratus lumborum muscle.
  Each lumbar ganglion, or the intermediate chord of the
 sympathetic, also  detaches branches internally, which are
 very small, and more or less interwoven with each other.
These branches get to the abdominal aorta, and, joining the
inferior mesenteric plexus upon it, are distributed along with
the latter. 
49;!
NERVOUS SYSTEM.
     Of the Sacral Ganglions of the Sympathetic.

  . There are generally three of these ganglions which may
be readily found: sometimes four or five.   They are situa-
ted in a line, on the anterior  face of the  sacrum, near the
corresponding foramina for the transmission of the  sacral
nerves; and are united with  each other  by intermediate
fibres,  from one to three in number, which are the continu-
ation of the sympathetic nerve.   Bichat  asserts, that fre-
quently the first of these ganglions is not  united to the last
of the  lumbar by an intermediate nerve,  so that there the
the continuity of the sympathetic is interrupted.
  Each ganglion  sends off, externally, one or more fila-
ments, by which  it  is united  to  the corresponding sacral
nerve:  it also detaches filaments in this direction to the py-
riformis and the levator ani muscles.
  Each ganglion likewise detaches, from  its internal mar-
gin,  ramifications,  which  go obliquely downwards  on the
front of the sacrum, and anastomose with corresponding
filaments from the opposite side.
  From  these  ganglions  many branches  pass forwards to
the hypogastric plexus; which is  formed  by them, by the
inferior mesenteric plexus,  and by a great many filaments
from the lower sacral nerves,  principally the third.   This
plexus is distributed upon the  rectum,  the bladder, vesicu-
lae seminales, and  prostate of the  male, and, in  place of the
two  latter in the female, upon the vagina and the uterus.
  The last sacral ganglion detaches downwards one or more
filaments, which lie upon the  front of  the os coccygis, and
anastomose with the corresponding filaments from the other
side, to form a sort of arch, the convexity  of which  is
downwards.   In  this manner,  terminates the chord of the
sympathetic nerve. 
UPPER NINE SPINAL NERVES.           493
                    CHAPTER III.

      OF THE NERVES OF THE MEDULLA SPINALIS.

  The nerves of the medulla spinalis, with the exception
of the first,  which from its position, is generally called the
Sub-occipital by anatomists, are arranged into cervical, dor-
sal, lumbar, and sacral,  according to the order of the  inter-
vertebral  foramina, through  which they  pass  out:  but  a
much better division would  be  Cervical,*  Thoracic, and
Abdominal.   Their mode of origin has been pointed  out in
the account of the medulla spinalis, as well as the ganglions
formed by them.


      SECT. I.--OF THE UPPER NINE SPINAL NERVES.

   These are spent upon the neck, upon the upper extremi-
ties,  and  upon  the  diaphragm.   They consist  in the Sub-
occipital Nerve, the Cervical, and the First Dorsal

               Of the Sub-occipital Nerve.

   The Sub-occipital Nerve (Nervus Infra-occipitalis, de-
cimus cerebri)  is one of the smallest  that proceeds from
the medulla spinalis.  It has the peculiarity, generally, of
arising  by  a  single root which  comes from  the anterior
chord of the medulla spinalis, between the occiput and the
first cervical vertebra.  This root consists of from two to
six or seven fasciculi, situated one above  another.   When
the  posterior root exists, it  is very small, is composed of
from one to three fasciculi, and anastomoses with the acces-
sory nerve.
   The trunk of this nerve passes from the vertebral  cavity
through the foramen formed in the dura mater  by the ver-
!*In diis case, the term Cervical would include the first eight, 
494
NERVOUS SYSTEM-
 tebral artery; it goes out below the latter, and between the
 occiput  and the first vertebra, behind  its superior oblique
 process.  It there  forms a small  long ganglion, like the
 other spinal nerves, and then divides into an anterior and a
 posterior fasciculus.
   The anterior fasciculus is the smaller of the two; it fol-
 lows, in some measure,  the course of the vertebral artery,
 and going forwards to  the  front of the transverse process,
 is then divided into several fine filaments, some of which
 go to the contiguous muscles on the front of the vertebrae;
 others join  themselves to  the pneumo-gastric and hypo-
 glossal nerves, and to the superior cervical ganglion of the
 sympathetic; others anastomose   with  the first  cervical
 nerve.
   The posterior fasciculus  runs backwards,  and  is distri-
 buted to the recti  and the obliquui muscles  on the back of
 the neck, and to the complexus.


                Of the Cervical Nerves.

   These are seven in number; the first one  gets from the
 spinal  cavity between the atlas and the dentata, and the last
 between the seventh cervical and the first dorsal vertebra.
 After the ganglion is formed upon the  posterior fasciculus
 of each, the trunk made by the union of the two fasciculi,
 divides almost immediately  again into an anterior and a pos-
 terior trunk.

              Of the First Cervical Nerve.

  The posterior trunk is the largest, and goes directly back-
wards.  It has its filaments distributed to many of the mus-
cles on  the  upper  posterior part of the cervical vertebrae,
and to  the integuments of the part.  Some of the branches
ascend through the muscles, near  the occiput; and, rising
up on the latter, are distributed upon its integuments,  and
upon the occipito-frontalis muscle.
  The anterior trunk is directed forwards under the inferior 
              UPPER NINE SPINAL NERVES.           495

oblique  muscle of  the  neck, and  then divides into two
branches, the superior joins the anterior branch of the sub-
occipital nerve, and anastomoses with the first cervical gan-
glion of the sympathetic,  and with the par vagum and the
hypoglossal nerve;  the inferior joins the anterior branch of
the second cervical nerve.

             Of the Second Cervical Nerve.

   This nerve issues between the second and the third cer-
vical vertebra.  Its posterior trunk is spent upon the trape-
 zius, complexus, and other muscles on the back of the^neck,
 and upon the integuments of the latter; it also  anastomoses
 with the posterior  trunk of the nerve above  and below.
   The anterior branch or  trunk detaches, first of all, some
 small filaments to  the  muscles on  the front of the cervical
 vertebrae; it then divides into two principal fasciculi, one of
 which ascends and the other descends.
   The ascending branch goes upwards and backwards, and
 early in its course anastomoses with the first cervical nerve,
 thereby forming with it a nervous noose; it then mounts
 upon the  occiput,  and is distributed upon the parts on the
 latter region, anterior to the occipital branches of the pre-
 ceding nerve.
    The descending branch turns over the posterior margin of
 the sterno-cleido mastoideus muscle, and gives filaments to
 it.   It is distributed afterwards by branches, some of which
 go to the  integuments of the middle and inferior parts of the
 neck,  (nervi subcutanei colli medii et inferiores;)  others
  go to  the integuments of the neck upon the angle and  the
  base of the lower  jaw, (nervi subcutanei superioress) and
  one to the external ear,  (nervus auricularus cervicalis.)
    From the anterior fasciculus of the second cervical nerve,
  there  proceeds a  filament  downwards, which is the upper
  root of the phrenic nerve; another filament from it joins the
  superior cervical ganglion of the sympathetic. 
496
NERVOUS SYSTEM.
              Of the Third Cervical Nerve.

  This nerve comes out between the third and  the  fourth
cervical vertebra.   Its posterior fasciculus is distributed to
the muscles on the back of the cervical vertebrae, and to the
integuments of the part; anastomosing, by its branches, with
the nerve above and below.
  The anterior  fasciculus is  larger than the posterior, and
goes obliquely downwards and outwards at  first; it sends
anastomotic branches to the nerve above and below; it also
anastomoses with the superior cervical ganglion of the sym-
pathetic and with the descendens noni.   One of its branches,
being joined by the branch just spoken of, from the second
cervical nerve, constitutes the root of the phrenic nerve. But
the principal number of its branches are distributed to the
integuments along the clavicle, (nervi supra claviculares,)
the upper part of the sternum, and  the  shoulder, some of
them going into the contiguous  muscles,  as the trapezius,
subclavius,  &c.  Several  anastomoses  exist between the
branches of this nerve and the terminating branches of the
nervus accessorius.

  The three preceding  cervical nerves form, by their anas-
tomoses with  each other, a plexus, consisting in a  number
of large loops or arches, which lie upon the sides of the mus-
cles connected with the transverse processes of the  cervical
vertebrae.  There are commonly two series of anastomoses,
the branches of the anterior one form the second series, and
from the latter proceeds, for the  most part,  the several
branches which have been described.   These  anastomoses
are covered by  the upper half of the sterno-cleido  mastoid
muscle, are involved in the cellular membrane  surrounding
the great vessels of  the neck, and are covered by the lym-
phatic glands.   Their intertexture and distribution are such,
that no adequate idea of them can be conveyed  without dis-
section.   From this plexus several branches go to the ster-
no-mastoid muscle, and  it is united above to the sub-occipital
nerve and below to  the fourth cervical. 
UPPER NINE SPINAL NERVES.
497
                 Of the Phrenic Nerve.

  The Phrenic Nerve (Nervus Phrenicus, Diaphragma-
ticus) arises, in the manner stated above, from the anterior
fasciculus of the second  and of the third cervical, and is as-
sisted  generally by two or three filaments  from the upper
part of the brachial plexus.   It descends vertically on the
humeral  side of the internal jugular vein, but  removed a
considerable distance from it, and  is attached, by cellular
substance,  to the front of the  scalenus  anticus  muscle.
Getting,  in its descent,  to the internal margin of the latter,
it passes  into the thorax, at the inner margin of the first rib,
between  the subclavian  artery, and the subclavian vein, the
latter being before it.   It then goes along the superior me-
diastinum to the pericardium, to the  side of which it ad-
heres in  front of the root of  the  lung,  being between the
pericardium and the corresponding portion of  the pleura;
it finally reaches the diaphragm, to which it is  distributed.
  J, ust before the phrenic nerve reaches the diaphragm, it
radiates into several branches, which interchange filaments.
Some of the branches are distributed to the convex surface
of the diaphragm; others penetrate the muscle,  and are dis-
tributed  in its thickness and upon its concave surface.   On
the right side some of these branches pass through the open-
ing for  the ascending vena cava, and thus getting into the
abdomen, anastomose with the solar plexus, and with the
pneumo-gastric nerve.
  The phrenic nerve of the left side is nearer to the root of
the lung  than that of the right, in consequence of the pro-
jection of the apex of the heart on that side.  Its  distribu-
tion in other respects does not present any remarkable dif-
ference from the other;  its branches radiate in the same way
to the  diaphragm, and supply its thickness, as well as its
upper and under surfaces.  It sends some  filaments  to the
lower part of the oesophagus.
  The phrenic  gives off in the neck a few filaments to the
scalenus anticus, and the rectus  anticus major muscle.  It
  Vol. II.—61 
198
NERVOUS SYSTEM.
also communicates there, with filaments from  the inferior
cervical ganglion,  and sometimes from the superior  cer-
vical.

         Of the Four Inferior Cervical Nerves.

  The trunks of these nerves, on issuing from the interver-
tebral  foramina, have one general mode of distribution,
which permits them to be described together or in common.
  The posterior branches are much smaller than those of the
preceding cervical nerves; they go backwards  between the
complexus and the transversalis colli, and leave filaments in
their passage with them; they then reach  the splenius and
the trapezius, to which and to the integuments of the neck
they are distributed.
  The anterior branches  are large; they appear on the side
of the neck, between the scalenus anticus, and medius mus-
cle; sometimes perforating the substance of one or the other
of these muscles.   They each detach filaments to the sym-
pathetic.  The fourth, also,  commonly sends one  to the
phrenic.  They then form the Brachial Plexus.


  Of the Brachial Plexus and the Nerves of the Upper
                      Extremity.

   The  Brachial or  the  Axillary Plexus  is formed by the
junction and the intertexture of the four  inferior cervical
nerves, and the first dorsal or thoracic.   It extends from the
scaleni muscles, to the axilla on a level with the neck of the
os humeri.  The nerves  at first converge, and are situated
somewhat behind the  subclavian artery where it passes
over the  first rib; but are at various heights  above it, ac-
cording to their origin, with the exception of  the first dor-
sal nerve, which  has to ascend  in  order to pass out of the
thorax.
   The plexus is  formed in the  following manner.  The
fourth and the fifth cervical nerves unite near the scaleni
muscles into a single trunk, which runs a short distance
downwards  and then splits into two.  The seventh cervical 
UPPER NINE SPINAL NERVES.
499
and the first dorsal do the same.  The sixth cervical is  the
central nerve of the plexus, and after going downwards two
or three inches, it bifurcates also.  Combinations of these
primary divisions are formed, which are dissolved and then
re-formed; in such a way that a thorough intertexture of the
original nerves  takes place.   This intertexture  surrounds
the axillary artery somewhat like the braids of a whip-cord,
from the clavicle to the os humeri below its head.  In this
course the axillary plexus passes along with the  artery be-
tween the subclavius muscle and the  first rib,  lies in  con-
tact with the superior part of the serratus major anticus mus-
cle, and immediately below the articulation of the shoulder
joint.  The axillary vein is in front of it.
   The  nerves  which proceed from the axillary plexus are
the Scapular; the Thoracic; the Axillary; the two Cutane-
ous : the  Radial; the Ulnar; and the Median.   They sup-
ply the superior extremity, including the shoulder and the
axilla.

   1.  The Nervus Scapularis is a small branch coming com-
monly from the upper part of the plexus, as  formed by the
fourth cervical nerve.   It goes backwards in company with
the arteria dorsalis superior scapulae, through the notch or fo-
ramen of the upper costa of the scapula; and having thus got
to the posterior face of the latter, it  gives filaments to the su-
pra spinatus muscle; continuing its course then on the pos-
terior face of the cervix scapulae, it is lost in filaments upon
the infra-spinatus and teres minor muscles.

   2.  The  Nervi Subscapulars of Bichat,  present some
varieties in their origin; occasionally they come from  the
same trunk, but commonly each one has its peculiar root
from  the  central parts of the axillary plexus.   There are
generally three of them.   One of them descends behind the
axillary vessels, between the subscapularis and  the serratus
major anticus;  it crosses the  teres  major, and  is lost upon
the contiguous  part of the latissimus dorsi.   Another is dis-
tributed  upon  the subscapularis muscle.   The third  des-
cends along the anterior margin of the subscapularis for n 
500
NERVOUS SYSTEM.
short distance, and distributes filaments to it, to  the teres
minor and major muscles.

   3.  The  Nervi Thoracici  are  primarily two or three in
number, and proceed from about the middle of the plexus.
The fasciculi into which they are resolved, may be distin-
guished as anterior and  posterior.   The former are distri-
buted by filaments, to the subclavian muscle, to the pecto-
ralis minor and major,  and to the integuments  covering
the latter.   The posterior thoracic has its origin somewhat
concealed by the scalenus anticus muscle.  It descends into
the axilla, adhering to the serratus major muscle  for some
distance, and is then, distributed  by many filaments to this
muscle.

   4.  The Nervus Axillaris, or Circumflexus, comes from
the inferior part of the plexus.   Immediately after its ori-
gin, it goes downwards and  outwards over the upper extre-
mity of the subscapularis muscle.   It then  winds around
the os humeri, between the  teres minor and major muscles,
observing the course of the posterior circumflex artery, and
finally terminates on the under surface of the deltoid mus-
cle.
   This nerve sometimes gives off the  subscapular, and in-
deed it is usual for anatomists to include the description of
the latter in it.   As it turns around the bone, it divides into
two principal trunks; the superior goes to the inferior margin
of the infra spinatus, and to  the posterior margin of the del-
toides;  the  inferior  is distributed principally in  the  sub-
stance of the deltoid muscle, but some of its filaments, by
perforating the latter, reach  the skin and constitute the ner-
vus cutaneus humeri.   Filaments go from  the nervus axil-
laris, in  the early part of its course, to the. subscapularis
and the two teres muscles.

   5.  The  Nervus Cutaneus Internus* arises from  the
lower part of the axillary plexus, and is one of the smallest
■* Antonius and Caldani, Tabid. CCI.VIII. 
           NERVES OF THE UPPER EXTREMITY.        501

of those which go to the  arm.  It is  situated between the
median and the ulnar  nerve, and  adheres  almost as far as
the elbow, to the basilic vein. In its descent, this nerve de-
taches several small filaments, which, perforating the fascia
of the arm, are distributed to the integuments of the biceps
muscle, and to those on the internal face of the triceps.
  Somewhat above the  bend of  the elbow, at the  place
where the median basilic vein joins the basilic, but occasion-
ally some inches higher up,  the internal cutaneous becomes
superficial and splits into two branches of nearly equal mag-
nitude, which diverge but  little  from  each other at first.
The branch nearest the internal  condyle of the os humeri,
lies in front of the basilic vein,  as it passes over the elbow
joint; and continues in this position for two or three inches;
it goes' down the front of the fore  arm on its ulnar side, but
inclines  continually to the back of the  fore  arm.   In this
course, it detaches small ramifications to  the integuments
about the internal  condyle, and about the heads of the flexor
muscles;  it also detaches continually, from its sides,  small
filaments to the integuments of the ulnar side of the fore
arm both anteriorly and  posteriorly, some of which reach to
the hand.   The other, or the external branch of the  inter-
nal cutaneous, which is nearer the radius, passes beneath the
median  basilic vein,  about  six lines  from the basilic; but,
just before it does so, it detaches a  very superficial cutaneous
filament, which crosses in front of the  median  basilic vein
about its middle, and  is  lost a little below the bend of the
arm.   The radial  branch of the internal cutaneous having
got from beneath the median basilic vein, goes superficially
as  far as the middle of the fore arm without sending off any
filaments of note;  it is then divided successively into seve-
ral, which diverge to  supply the skin down to the wrist.

   6.  The Nervus Musculo-Cutaneus or Cutaneus Exter-
nus, is somewhat larger  than the preceding, and arises from
about  the middle of the brachial plexus.   It  descends  a
short distance, and then perforates obliquely the upper part
of  the coraco-brachialis muscle.   Having passed through 
502
NERVOUS SYSTEM.
 this muscle, it continues its course obliquely, between the
 brachialis internus and the biceps flexor, and finally makes
 its appearance superficially on the outer side of the tendon
 of the latter.  In this course, it distributes filaments to the
 several muscles with which it is connected.
   It afterwards passes the elbow joint under the median ce-
 phalic vein near its middle, and descends between the skin
 and the fascia of the fore arm, near the outer margin of the
 median vein, to the hand;  in  this course it is parallel with
 and on the front of the supinator  radii longus.  It distri-
 butes  many filaments to the corresponding integuments on
 the radial side of the fore-arm, and, having at length got
 near the  lower  end of the radius, it  divides into two or-
 ders  of fibres, one of which is distributed to  the  integu-
 ments on the dorsal, and the other to those on the palmar
 side of the hand, about the root of the thumb.

   7.  The Nervus  Radialis, or Musculo-Spiralis, arises
 from the upper portion of the brachial plexus, but in such
 a  way that filaments from almost every part of the latter run
 into it.   It is a large trunk which winds spirally around the
 os humeri, between the triceps muscle and the bone, enter-
 ing the fissure between the third and  the  first head of the
 triceps.  It appears on the outside of the os humeri, between
 the brachialis internus and the triceps muscle, running for
 some inches in contact with their intermuscular ligament.
 While beneath the triceps, it sends several branches to its
 heads.  There are  three principal  trunks afterwards from
 this nerve.
   a. The Ramus Superficial  Dorsalis is sent from it on a
line with the point of the deltoid muscle.  This  branch
then goes just below the  skin, parallel with and  over the
external ridge of the os humeri; it of course crosses the ori-
 gin of  the muscles of the external  condyle.   It continues
superficial on  the posterior external edge of the supinator
radii longus muscle,  and terminates in the integuments on
the back of the hand.
   The continued  trunk of the muscular spiral  goes in the 
           NERVES OF THE UPPER EXTREMITY.        503

interstice between the extensor muscles of the hand and the
brachialis internus, and at the external condyle divides into
the other  two branches, from which  filaments proceed to
the contiguous heads of the muscles.
  b  The  Ramus Profundus  Dorsalis perforates  the supi-
nator brevis muscle, getting beneath the radial extensors to
the back of the fore-arm;  it is then  distributed in numerous
filaments to the muscles on the back of  the fore arm, some
of its branches reaching to the wrist.
  c. The Ramus Superficialis Anterior  seems to  be a con-
tinuation of the main  trunk  of the nerve, and  descending
at the anterior margin of  the supinator radii longus muscle,
it joins  with the radial artery and continues in its  company
to a short distance below the middle of the  radius.  Here
it crosses the bone obliquely  beneath the tendon of the su-
pinator longus, and  then divides into a palmar and a dor-
sal ramuscle;  the first  being  distributed to the muscles and
integuments of the thumb, the  second terminating so as to
supply the back of the hand, of the  thumb, fore, middle,
and ring fingers to their extremities.

   8. The  Nervus Medianus, descends  the arm  at the in-
ner edge of the biceps muscle; along the anterior  surface of
the brachial artery, adhering  firmly to it,  and  the deep-
seated veins, by cellular substance.  As far as the elbow, it
sends off no branch of importance.  There it lies at the side
of the biceps tendon, crosses the lower part of the  brachialis
internus,, and is beneath the aponeurosis of the biceps.  It
then perforates  the pronator teres and gets  between the
flexor sublimis digitorum, and the flexor longus pollicis, and
enters the  palm of the hand under the ligamentum carpi, at
the radial  edge of the tendons of the flexor sublimis.   In
the palm it is situated  beneath the aponeurosis palmaris and
the arcus sublimis of the arteries.
   The median nerve dispenses the  following branches; At
the bend of the arm,  it furnishes filaments to  the heads of
the first layer of muscles of the fore-arm; and a little below,
it detaches the nervus interosseus, which supplies filaments 
504
NERVOUS SYSTEM.
to the flexor longus pollicis and flexor profundus digitorum.
The interosseous nerve then descends with the interosseous
artery in front of the interosseous ligament, and terminates
in the pronator quadratus. Before the median nerve reaches
the wrist it sends a branch which supplies with filaments,
the muscles and integuments of the ball of the thumb.  In
the palm of the hand it divides and subdivides so as to send
a branch to each side of the  thumb, of the fore, and of  the
middle finger, and to one side of the ring finger.   These
branches go along with the  arteries to the ends of the  fin-
gers and thumb.

   9.  The Nervus Ulnaris comes  from the  lowest section
of the brachial plexus.  It descends along the internal an-
terior part of the triceps muscle, in a groove formed between
it and the intermuscular ligament; it diverges in this course
gradually from the median nerve till it reaches the elbow,
when it is at its greatest point of separation.  At the elbow,
it is behind the internal condyle, in the groove between it
and the olecranon, and separates the two heads of the flexor
ulnaris muscle.  It then gets to the fore-arm  between  this
muscle and  the flexor  profundus digitorum,  and continues
between them to within two  inches of the wrist joint, when
it detaches the Ramus  Dorsalis.
  The Ramus Dorsalis slips between the ulna and the ten-
don of the flexor ulnaris, runs along the internal margin of
the ulna to the carpus;  it then divides into ramuscles, which
supply the ulnar side of the integuments on the back  of the
hand, and on the backs of the two last fingers.  At the in-
terval  behind, between the heads of the metacarpal  bones
of the middle and ring fingers, a considerable ramuscle joins
one from the branch  of the muscular spiral nerve which at-
tended the  radial  artery.
  The Ulnar Nerve, having given off this dorsal  branch,
descends along the radial margin of the tendon of the  flexor
ulnaris and the os pisiforme, above the annular ligament,
to the palm  of the hand.   Getting beneath the aponeurosis,
it there detaches first a deep-seated branch, which penetrates 
               THORACIC SPINAL NERVES.             505

the muscles of the little finger to supply them, the interos-
sei, and the short flexor of the  thumb.   The ulnar  nerve
then furnishes a superficial branch,  and afterwards divides
into three; one for the ulnar side of the little finger, another
for the opposing sides of the little and ring finger, and a third
which joins the most  internal digital branch of the median
nerve.


      SECT. II.—OF THE THORACIC SPINAL NERVES.

   The Dorsal or Thoracic Spinal Nerves (Nervi Thoracici,
Dorsales) consist in twelve pairs, the first pair goes through
the intervertebral foramina, between the first and the second
dorsal vertebra, and the twelfth pair between the last dor-
sal and  the  first  lumbar vertebra.   The  common  trunk
formed  after  the  ganglion of each nerve, goes but a short
distance when it  divides into  an  anterior and a posterior
branch.
   The Posterior Branch (Ramus Dorsalis) of each nerve,
goes backwards between the transverse processes of the cor-
responding vertebrae,  and,  having got beneath the multifi-
dus spinae, is commonly subdivided  into internal and  exter-
nal ramuscles.   The  internal are the smaller, and are  dis-
tributed upon the  muscles lying upon the spine, as the mul-
tifidus,'the sacro-lumbalis, longissimus dorsi, and so  on;
their terminating filaments reach the  skin.   The external
branches descend obliquely outwards beneath the longissi-
mus dorsi, and then issue between the latter and the sacro-;
lumbalis, to both  of  which they dispense  filaments; they
afterwards are divided into branches,  which go to the  tra-
pezius,  latissimus  dorsi, rhomboideus,  and to the corres-
ponding integuments.
   The Anterior  Branches of  the  Dorsal  Nerves (Rami
Subcostales) correspond with the intercostal spaces of  the
ribs.  Each one, in a short course  after its origin, applies
itself to the rib just above it, and accompanies the intercos-
tal vessels  in the  groove,  formed  in the under margin of
   Vol.  II.—64 
506
NERVOUS SYSTEM.
each rib.   After it proceeds about two thirds of the length
of the rib, it separates  gradually from it, and  goes nearer
the middle of the intercostal space and the superior margin
of the rib below.  To the angle of the  rib, each nerve is
only covered in front by the pleura, but afterwards it goes
between the intercostal  muscles.   Near  the sternum, the
branches become superficial by escaping from between the
intercostal muscles,  and are distributed upon the pectoral
muscles and the adjacent skin.  These terminating branches
of the five or six inferior dorsal nerves go to the upper por-
tions of the abdominal muscles and their integuments. Not
far from its origin, each dorsal nerve anastomoses with the
ganglion or chord of the sympathetic, after the manner de-
scribed in the account of the latter nerve.

   There are some  differences  between the thoracic nerves
in their manner of distribution.
   The anterior fasciculus of the first, as mentioned, forms
the lower  part of  the axillary plexus  by joining  itself to
the seventh cervical.  It sends out, however,  a subcostal
branch which goes along the  inferior  face of the first rib,
supplying the intercostal muscles and having the general
distribution alluded to.
   The Second Sub-costal Branch,  besides the common dis-
tribution, detaches a fasciculus which penetrating between
the ribs, gets into the axilla and is augmented  by a branch
from the internal cutaneous nerve of the upper extremity.
It then descends along the internal posterior face of the arm
to the elbow, and in  this course  detaches several fine fila-
ments to the integuments.
   The Third Subcostal  Branch in like manner detaches an
axillary fasciculus  which goes to  the  inferior part  of the
arm-pit, to the  integuments of which,  and  to  those on the
internal face of the arm, it is distributed.   It does not de-
scend quite so low as the preceding.  These  two nerves are
called Intercosto-Humeral, and from their origin and course,
are supposed to account for the  numbness  of  the arm, in
cases of angina pectoris. 
THORACIC SPINAL NERVES.
507
  The Fourth, Fifth, Sixth, and Seventh Subcostal Branches
of the Dorsal or Thoracic Nerves, about the middle of the
ribs to which they respectively belong, are all divided into
two branches.   One of them, which  is properly speakjng
the intercostal, continues in the intercostal space, giving fila-
ments to its muscles  and to  the  triangularis sterni; it then
emerges near the sternum to terminate upon the great pec-
toral muscle, the mamma and the integuments of the front
of the thorax.   The other branch is the  external pectoral,
it extricates itself earlier  from the intercostal space, and is
distributed upon the muscles and the integuments on the
side of  the thorax.
   The remaining subcostal branches,  to the eleventh inclu-
sively,  have very much the same principle of distribution.
Their intercostal fasciculi, having reached the anterior ends
of the intercostal spaces, pass on to the abdominal parietes,
between the transversalis muscle and the internal oblique,
to both of which they give filaments.   They reach  the ex-
ternal margin of the rectus abdominis muscle, and then  di-
vide into filaments, some of which go to this muscle, others
pierce the fore part of its sheath and  are ramified upon the
integuments of the front of the  abdomen.
   The  Twelfth Subcostal Branch of the  Dorsal  Nerves,
sends first a branch  downwards, which joins with the first
lumbar nerve.   The subcostal nerve then crosses in front
of the  quadratus lumborum muscle,  to which it gives fila-
ments as well as to the adjoining portion of the diaphragm.
It afterwards divides into  two  branches, the superior  of
which goes for some distance between the two oblique mus-
cles  of the  abdomen, detaching filaments to  them,  and
finally terminates on the integuments of the  abdomen; the
other branch goes between  the  transversalis  and the inter-
nal oblique, and is extended to the lower part of the rectus,
and to the pyramidalis muscle, to all of which it distributes
filaments. 
508
NERVOUS SYSTEM.
     SECT. III.—OF THE ABDOMINAL SPINAL NERVES.

  There are five lumbar, and five, sometimes  six, sacral
nerves on each side; the first of  them passes out of the in-
tervertebral foramen, between the first and the second lum-
bar vertebra; and the remaining lumbar and sacral nerves
go successively,  through  the foramina in the loins and in
the sacrum.
  The anterior  fasciculi of  these nerves, form  a plexus
which extends from the upper part of the loins to the lower
part of the sacrum;  it is designated under the general term
of Plexus Cruralis.  The posterior fasciculi are much smaller.
Those of the loins  go backwards  between the transverse
processes, and are distributed upon the  sacro-Jumbalis, the
longissimus dorsi, the multifidus spinae, and the correspond-
ing integuments.  The posterior fasciculi  of the sacral nerves
are not so large,  generally, as those of the lumbar; they get
out through the  foramina, on the posterior face of the sa-
crum; are distributed to the same muscles; to the origin of
the glutaeus magnus, and to the integuments of the sacrum,
and of the adjoining portion of the buttocks.
  The Plexus Cruralis, for the purpose of description, has
been  divided  by anatomists into the  Plexus Lumbalis,
formed by the four  superior lumbar nerves, and the Plexus
Ischiadicus, formed  by the last lumbar and the sacral nerves.
  The Lumbar Plexus (Plexus Lumbalis) is concealed by
the psoas magnus muscle, and is placed between it, the lum-
bar vertebrae, and the quadratus lumborum: frequently the
roots of the nerves  forming  this plexus  penetrate through
the substance of  the psoas magnus and  form their unions
in it.   The plexus is narrow and pointed above, where it
commences by the fasciculus of the last dorsal nerve joining
the first  lumbar; but it increases continually afterwards in
breadth,  owing  to  the nerves composing it, successively
anastomosing further and further from the spinal column.
From this plexus proceed three principal trunks; the upper
one (Cruralis Anterior) is of considerable size;  and  goes 
ABDOMINAL SPINAL NERVES.           509
to the skin and the muscles on the front of the lower extre-
mity; the middle (Nervus Obturator) is not so large as the
preceding, and goes through the obturator foramen to the
adductor muscles of the thigh; the inferior, formed  by the
whole of the fifth and a fasciculus from  the fourth lumbar
nerve, joins the upper part of the sciatic plexus in the pel-
vis.   Besides these, there are several branches of smaller
size and of  less importance, proceeding from the lumbar
plexus.

  The Abdomino  Crural  Branches, according to Bichat,
are most commonly three in number, and come from the
two upper lumbar nerves.  The first of them goes obliquely
downwards  and outwards, in front of the quadratus lumbo-
rum,  to the posterior  part of the  spine of the ilium, and
runs for a short distance along the crista of the bone: it
gives filaments to the iliacus internus, and  to the abdominal
muscles where they border on this part of the bone.  Some
of the filaments become cutaneous, but the main trunk of
the nerve reaches the anterior superior spinous process, by
going between the transversalis and the  internal oblique
muscle; it then follows the inguinal arch to the external
ring, through which  it passes, and is distributed in filaments
upon the groin, the pubes,  and  the scrotum.   The  second
or middle branch arises from the plexus near the preceding;
it descends along the external margin of the psoas magnus
and crosses  the iliacus internus, covered by the peritoneum;
near the anterior superior spinous process, it gets between
the lower margins of the abdominal muscles, and is distri-
buted upon them there; some of its  ramifications get also
through the external ring and may be  traced to the scro-
tum.    The  third  or the inferior  branch  arises from the
plexus  still  lower down, and, after having traversed the
front of the  iliacus internus, it emerges from the pelvis be-
neath Poupart's ligament, near the anterior  superior spinous
process; it then divides into filaments  which penetrate to
the skin through  the  femoral fascia, and are distributed
along the external  anterior face of the thigh. 
510                NERVOUS SYSTEM.
   The Spermaticus Externus arises from the upper part
of the plexus, by a fasciculus from the first lumbar nerve,
which is increased by one from the second lumbar.  It de-
scends at first in the body of the psoas magnus muscle and
then in front of it; it crosses the iliacus internus, somewhat
above Poupart's Ligament, by directing its course towards
the anterior superior spinous process of the ilium.   Here
it involves itself in the edge of the abdominal muscles, and
goes on the posterior face of Poupart's ligament; at the in-
ternal abdominal ring it joins the spermatic chord  of the
male, or the round ligament of the uterus  of the female.
In the first case it is distributed to the spermatic chord and
scrotum; in the second  to the labium externum and mons
veneris.

   The Cutaneus Externus arises from the lumbar plexus
below the external spermatic.  It passes across the  iliacus
internus towards the anterior superior spinous process, about
an  inch  below the spermaticus externus, and crosses the
latter nerve just at that process.   Emerging from the ab-
domen, by  penetrating the commencement  of Poupart's
ligament, it is distributed in several branches to the inte-
guments of the vastus  externus muscle,  and along the
edge of the rectus femoris; one of the latter extends to the
patella.

  The Cutaneus Medius is detached from the anterior cru-
ral, an inch or so above Poupart's ligament. It arises among
the cluster of  branches, which come off there to be  distri-
buted to  the-iliacus internus muscle, and to the muscles  of
the thigh.   It appears superficially on the thigh, for the
first time, by penetrating the sartorius  muscle, about the
internal  edge  of the rectus femoris; it descends then along
the same edge of the latter muscle, and is distributed to its
integuments.  It does  not  descend so low as the external
cutaneous.

  The Cutaneus Anterior arises also from the crural nerve.
It is on the inner side of the cutaneus  medius, emerges 
ABDOMINAL SPINAL NERVES.
511
from the fascia of the thigh, and crosses the sartorius mus-
cle two or three inches below the cutaneus medius.  It is
distributed on the integuments of the vastus internus muscle,
and some of its'branches extend to the internal edge of the
patella.

  The Cutaneus Internus arises from the anterior crural
nerve, among the same cluster  above Poupart's ligament.
It divides into four or five branches of different lengths, and
is distributed to the integuments of  the adductor muscles,
and along the inner front side  of the thigh.   One branch
observes, very much, the course  of the tendon of the ad-
ductor magnus,  and reaches as far  down  as the inner side
of the knee.

   The Cruralis Anterior arises from the middle  nerve of
 the lumbar plexus;  at first it is beneath the psoas  magnus
 muscle; it then gets to its  outside, and passes from the ab-
domen, under Poupart's ligament, about half an inch from
the outside of the femoral artery.  Before it reaches Pou-
 part's ligament it gives off a cluster  of nerves, several of
 which go to the iliacus internus muscle; others form the su-
 perficial or cutaneous nerves of the thigh just mentioned, and
 others the deep seated or muscular branches, which supply
 the adductor muscles, the four extensors, the pectineus, the
 sartorius, and the gracilis.

   One of the branches of the anterior crural nerve is seen
 to accompany the femoral artery, till  the artery penetrates
 the adductor magnus, it-then runs along the front margin of
 the tendon of the adductors in a theca formed by this tendon
 and the origin of the vastus  internus.   The nerve alluded to
 is the Saphenus; it passes afterwards between the internal
 condyle of the os femoris and the sartorius muscle, attaches
 itself to the saphena vein,  and is distributed to the integu-
 ments of the inner side of the leg, and of the upper internal
 parts of the foot.

   The Nervus Obturatorius is derived from the middle of 
512
NERVOUS SYSTEM.
the lumbar plexus also; and has very much the same posi-
tion, in regard to the psoas magnus, as the anterior crural
nerve.   It descends into the pelvis from beneath the psoas
magnus,  near the  sacro-iliac articulation; and passes for-
wards and downwards to the obturator foramen, having got
through which,  it divides into an anterior and  posterior
branch.   The first is distributed to the head of the adduc-
tor longus and brevis,  and to the gracilis and integuments.
The  second terminates in  the obturator externus, and the
adductor magnus.

   The Sciatic Plexus  (Plexus Ischiadicus,) is formed by
the  union  of the last  lumbar with the  four upper sacral
nerves; the last lumbar, before it joins the plexus, receiving
the branch of the fourth lumbar  nerve, which is  left after
the lumbar plexus is formed.   This plexus is situated at the
side of the rectum before the pyriformis muscle.
   TheTolume of the posterior branches of the Sacral Nerves
increases till the fourth; but the fifth and the sixth are much
smaller,  in fact only fibrillae.
   The anterior  branches of the  sacral  nerves are much
larger than the posterior.  The four first communicate with
the sacral ganglions of the great sympathetic,  besides form-
ing the ischiatic plexus.  The third and the fourth, assisted
by the  sympathetic, form the hypogastric plexus.   The
fifth, and the sixth when it  exists, are distributed to the
coccygeus,  sphincter, and levator ani.*

   The following small branches go from the Sciatic Plexus.i
   a.  Nervi Glutasi; one passes through the upper part of
the sciatic notch along with the artery, to the glutaeus  me-

  * This is only given as the most frequent arrangement of the sciatic plex-
us, and of  the branches of nerves which proceed from it; other arrange-
ments wdl  often be met with in the cavity of  the pelvis, in which not so
many sacral nerves  are sent to the plexus ischiadicus, and  the several
branches proceeding from it, depart in a different manner.
  f They sometimes come from a common trunk called, in such case, the
Small Sciatic. 
ABDOMINAL SPINAL NERVES,
513
dius and minimus; another below the pyriformis muscle to
the glutaeus magnus.
  b. Nervus Pudendalis Longus Inferior, passes under
the tuber of the ischium to the glutaeus magnus;  perineal
muscles; urethra  and integuments of the  penis and scro-
tum in men; and to the inferior parts of the labium exter-
num in women.
  c. Ramus Femoralis Cutaneus Posterior.  This nerve
is placed between the integuments of the  thigh, and the
muscles which arise from the tuberosity of the ischium.   It
sends many branches successively to the skin  on  the back
of  the thigh; one of its branches, longer than the others,
goes down to the ham, and there  divides into  several fila-
ments, which are distributed to the integuments on the back
of the leg.

   The Nervus  Pudendalis Longus Superior comes from
the third and fourth  sacral.   It goes in company  with the
internal  pudic  artery between  the sacro-sciatic ligaments,
and then  divides  into two  branches; the inferior is distri-
buted to the integuments  and muscles of the perineum, to
the urethra and scrotum; the superior passing along the ra-
mus of the ischium and pubes, with the trunk of the inter-
nal pudic artery, is distributed to the obturator  internus, ac-
celerator urinae, urethra, and afterwards getting between the
symphysis of the pubes and the penis, terminates  on its in-
teguments and the glans penis.

   The Nervus Ischiadicus, or the Great Sciatic, is the com-
mon trunk formed from the sciatic plexus; it  is much the
largest  nerve in  the body, and passes from the pelvis be-
tween the pyriformis and the geminus superior.  It crosses
vertically, the small rotator muscles of the thigh, being con-
cealed by the inferior edge of the glutaeus magnus; it is there
about half-way between the tuberosity of  the  ischium and
the trochanter major.  Thence it descends on the back of
the adductor magnus, at the outer edge of the  long head of
the biceps flexor cruris.   About half way down the thigh,
sometimes a little lower, the Sciatic Nerve divides into the
   T7"-_  IT   m 
514
NERVOUS SYSTEM.
 Popliteal or Posterior Tibial, and Peroneal.  Occasionally
 this division takes place as high as the exit  of  the  nerve
 from the pelvis; but in this  case the fasciculi are parallel
 with each other as far as the middle of the thigh.   From
 the trochanter minor to its usual place of division, this nerve
 is parallel with, and on the back of the thigh bone; afterwards
 the two branches begin to  diverge.   The popliteal nerve
 continues straight downwards to the back and middle of the
 knee joint, and to the interstice between the heads of the
 gastrocnemius muscle;  whereas the peroneal nerve goes
 along the inner posterior edge of the  biceps  flexor cruris,
 and passes between its tendinous insertion and the external
 head of the gastrocnemius muscle.

   In this course  the following branches are sent from the
 sciatic.—Twigs to  the little rotator muscles of the thigh.—
 The  Cutaneus Internus  Superior,  which  arises near the
 upper part of the thigh, and is distributed to the skin of
 of the corresponding part.—The Cutaneus Internus Infe-
 rior, which arises just below the last, and descending upon
 the inner head of the gastrocnemius, is distributed to the in-
 teguments of the calf of the leg.—A large trunk,  and some-
 times instead of it, distinct branches which go the Adduc-
 tor Magnus,  Semi-membranosus, Biceps, and Semitendi-
 nosus.

   The Peroneal  Nerve (Nervus Peroneus) divides at the
 head of the fibula into two branches, the  Peroneus Exter-
 nus and the Tibialis Anterior; but, before  this division, it
 sends a small branch to the external  parts of the knee joint
 and  two cutaneous branches  called  Peroneo-Cutaneous.
 The internal Peroneo-Cutaneo descends behind  the exter-
 nal head of the  gastrocnemius, and, at the bottom of the
 leg, is united to a division of the posterior tibial  called the
 External  Saphenus or  Communicans  Tibiae.   The exter-
 nal Peroneo-Cutaneous is distributed to the skin along the
 fibula.
  The External Peroneal Nerve (Peroneus Externus) gets
between the head of the peroneus longus and the fibula, 
ABDOMINAL SPINAL NERVES.
515
then between the peroneus longus and the extensor longus
digitorum.   It  descends at the outer edge of the last mus-
cle to the inferior third of the leg, giving out, in the mean
time, many muscular branches.  Here it penetrates the apo-
neurosis and divides into subcutaneous branches,  which sup-
ply the lower part of the leg, and the upper surface of the
foot and toes.  This nerve is called, by the French, the
Musculo-Cutaneous of the leg.
  The Anterior Tibial Nerve (Tibialis Anterior) gets ob-
liquely between the fibula, the peroneus longus,  and the ex-
tensor longus digitorum to the front of the interosseous li-
gament, where it accompanies the anterior tibial artery. It
passes with  the artery under the annular ligament of the
ankle, has its terminating filaments going to the muscles and
integuments of the upper surface of the  foot, as far as the
end of the two first toes.  One of its branches  sinks down
with the anterior tibial artery to the sole of the  foot. High
up  in the leg it gives filaments to the knee joint, and, in its
course downwards, it furnishes the muscles on  the front of
the leg.

   The Posterior Tibial or Popliteal Nerve (Nervus Popli-
 teus) having the direction mentioned, is placed between the
 skin and the popliteal vein.   It gets between the heads of
 the gastrocnemius muscle, and perforates the origin  of the
 soleus; going with the posterior tibial artery, between this
muscle and  the flexor longus digitorum, to the bottom of
the leg.  It gives off the following branches:
  a. The External Saphenus (Saphenus Externus or Com^
municans Tibiae) which arises above the knee joint, and,
descending  between the skin and the gastrocnemius, turns
outwardly,  and anastomoses with the cutaneous branch al-
luded to', of the peroneal nerve.   The common trunk thus
formed passes behind the external ankle, along the external
margin of the foot, and terminates on the last toes,  having
given off a great number of cutaneous  branches.
  b. Branches to the heads  of the gastrocnemius,  soleus,
plantaris, and popliteus. 
516
NERVOUS SYSTEM.
   c. Branches to the flexor longus digitorum, tibialis pos-
ticus, and to the flexor longus pollicis pedis.
   d. A branch through the interosseous ligament, above, to
the tibialis anticus.
   e. At  the inferior part  of the leg many cutaneous fila-
ments,-one of which gets to the sole of the foot.

   The Posterior  Tibial  Nerve,  having  given  off  these
branches, divides in the hollow of the os calcis into Inter-
nal and External Plantar Nerves.

   The  Internal  Plantar  (Plantaris Internus) proceeds
alongside of the tendon of the flexor longus muscle of the
great toe and the flexor longus digitorum, and gives filaments
to the contiguous muscles.  It then divides in such a way as
to furnish the two sides of the three first toes and the inter-
nal side of the fourth.

   The External  Plantar (Plantaris Externus) proceeds
with the  artery of the same name to the outer  edge of the
foot, between the flexor brevis digitorum  and the  flexor
accessorius.   It is distributed to the two  sides of the lit-
tle toe, and  to the external side of the fourth toe.   One
branch penetrates to the  interosseous muscles and to the
transversalis pedis.   A branch of  considerable size  is de-
tached, near the heel, to the muscles and integuments con-
nected with  the os calcis. 
INDEX TO VOL.  II.
                                                   Page
                                                      c
Abdomen Generally,    -       -      -
         General Situation of the Viscera ot,      -        '
         Veins of,                  -                  „
Abdominal  Aorta, Branches of,     -      -             ~
Absorbent Glands of the Abdomen,    -             -  JJJJ
                      Head and Neck,  -       -      291
                      Lower Extremity,     -      -  29b
                      Upper Extremity,        -      293
                      Thorax,      -       -      -  ^09
 Absorbents of the Pelvis,    -       -      -      -      ^b
                 Head and Neck,    -       -      -289
                 Upper Extremities  and  the Contiguous
                   Parts of the Trunk of the Body,  -  292
                 Inferior Extremities and the Contiguous
                   Parts of the Trunk of the Body,   -   294
                 Organs of Digestion,    -      -      298
                 Parietes of the Trunk,      -       -   307
                 Viscera of the Thorax,   -      -      304
 Absorbent System, Special Anatomy  of,       -       -   289
                  General Anatomy of,   -      -      280
 Accelerator Urinae,            -     -      -      "   ,??
 Aorta and the Branches from its  Curvature,      -      190
 Aqueous Humour,      ...      -      -   420
 Aqueducts of Ear,                                    439
 Arachnoidae,    ------  342
 Areola,     -----             "9
 Arcus Sublimis,     .  -       -      -      -      "  ^
 Arteries,    ------       190
         Texture of,    -      -     -      -      "I
  Arteria Basilaris,   -----      383
         ad Cutem Abdominis,  -                      236
         Alveolaris Superior,       ...      202
         Anastomotica, (Arm,)  -      -      -      -   211
         Anastomotica, (Thigh,)    -     -      -      239
         Articularis Superior Interna,  -      -      -   240
             —       —   Externa,     -      -      240
             —    Media,     -      -      -       -   240
             —    Inferior Externa,     -      -      241
             —       —  Interna,    -      -       -   240 
Mb
INDEX.
                                                       Page
Arteria Auricularis Posterior,      -       -    Vol. II.  198
        Buccalis,       -                                202
        Callosa,     -----       38j
        Carotis Primitiva,      -                         192
          —   Interna,     -      -      -      -       193
          —   Externa,       -       -       -       -    194
        Cavernosa Profunda Penis,        -     . -      233
        Caeliaca,        -                               219
        Centralis Retinae,   -
        Cerebri Posterior,      -       -       -       -   383
        Cervicalis Posterior,        -      -      -      206
        Choroidea,      -----   381
        Ciliaris,    -      -              -      -  398-412
        Circumflexa Anterior,  -                        209
            —     Posterior,      -       -      -      210
            —     Externa,   -                        237
            —     Interna,       -                     237
            —     Ilii,       -      -       -       -   234
        Colica Sinistra Superior,    -                     223
          —    —    Media,         -       -       -   223
          —    —    Inferior,    -       - •      -      224
        Communicans Posterior,       -                 381
        Dentalis Inferior,   -       -       -       -      201
       Dorsalis Carpi,  -       -       -       -       -213
          —   Halucis, .  -       -       -       -       244
          —   Manus,        -                         215
       Epigastrica,        ....      234
        Facialis,        -       -       -       -       -   196
        Femoralis,  -----      235
       Frontalis,       -                                400
       Gastrica,    -      -       -       -              219
       Gastrica Dextra,       -       -       -       .   220
          —   Sinistra,   -       -       -       -       221
       Glutea,         -       -       -       -       -   230
       Haemorrhoidea Inferior Externa,    -      -       232
             —      Media,  -                         229
             —      Superior Interna,   -      -       224
       Hepatica,      -----   220
       Iliaca Interna,      -                            227
         —  Externa,         -                         233
       llio-Lumbaris,      -                             228
       Innominata,    -       -       -       -       -   191
       Intercostalis Superior,      -       -       -       204
       Interossea Anterior,    -                         214
           —    Posterior,        -       -      -       215
       Infra-Orbitalis, •        -                         202
       Inferior Cerebelli,  -       -       -      -       383
       Ischiadica,     -       -       -      -       -   231
       Lachrymalis,       ....       398
       Lingualis,      -       -       -       -       ..   101 
1NUEX.
519
Page
Arteria Magna Pollicis,     -      -      -     VoL- IL f5
       Mammaria Interna,     -       -       -      -  -f J
       Maxillaris Interna,        '      "      '      m
       Malleolaris Externa,    -       -       -      '  ztt
—     Interna,
—     Superior,
—    Superior,
242
Mesenterica Inferior,   -      -       -       -   223
                                               221
Metatarsea,   r-      -       -       "       "25
Meningea Parva,                               ^u
Musculares Orbitales,  -       -       -       '   0\i
Nutritia,.....*tl
Nasalis,         -----   400
Obturatona,        "      "      "      "      Vno
Occipitalis,.....]J*
CEthmoidalis,      '""'to
Palatina Superior,      -                        202
Palmaris Profunda,        -      -      -      213
Palpebrals     -       -       -      ■-       -   400
Pedoeia,    -----      <&**
Perinea,        ."""""   f«f
Pharyngea Inferior,       -                    19'
                                               202
Plantaris Interna,    -      -       -       -      246
    —    Externa,    -      -      -      -   246
Poplitca,    -----      239
Profunda Femoris,     -      -      -      :   236
Profunda Major Humeri,   -                     210
    —   Minor,        -       -      -      -   211
Pudica Interna,    -                           232
Radialis,.....212
    —  Indicis,                                213
Recurrens Radialis,     -                        212
    —    Ulnaris,        -       -       -      214
Sacra Media,   -----   226
Scapularis,.....209
Superior Scapulae,      -                        207
Spheno-palatina,    -                           203
Superficialis Volae,      ...       -   213
Superior Cerebelli,         -                     383
Splenica,.....220
Tarsea,     -       -      -       -             243
Temporalis,    -       -       -       -       -   199
Thyroidea Inferior,        -       -       -      204
    —    Superior,    -       -       -       -   194
Thoracica Longa,   ...       -      208
    —   Acromial is,   -       -       -       -   208
    —   Axillaris,                             209
    —   Superior,     -                        208
Tibialis Anterior,   -                           242
Tibialis Postica,        -       -      -       -  244 
520
INDEX-
			Page
Arteria Tibialis Recurrens,	-	-	Vol. II. 242
Tympanica,		-	- 200
Ulnaris, *	-	-	213
Uterina,		-	- 230
Vertebralis,	-	-	- 204-382
Arteriae Bronchiales,		-	- 216
CEsophageae,	-	-	217
Capsulares,		-	- 224
Emulgentes, Gastricae Breves,	-	-	224
		-	- 221
Gemellae, -	-	-	241
Intercostales Inferiores Aorticae,			- 217
Iliacae Primitivse, -	-	-	227
Lum bares,		-	- 225
Mediastinales Posteriores	i	-	217
Pancreaticae Mediae et Sinistra?,			- 221
Phrenicae,	-	-	218
Pterygoideae, -		-	- 201
Pudendae Externae,	-	-	236
Sacrae Laterales,		-	- 228
Spermaticae,	-	-	225
Temporales Profundae,		-	- 201
Vesicales,	-	-	229
Arytenoid Cartilages,		'-	- 123
Aryteno-Epiglottideus,	-	-	127
Arytenoideus Obliquus,		-	127
Transversus,	-	-	127
Auditory Nerve,		-	- 441
Axillary Artery, Branches of,	-	-	207
Biliary Ducts,		-	55
Bile,	-	-	56
Bladder, -		-	74
Structure of,	-	-	75
Blood, - - - -		-	- 168
Coagulating Lymph of,	-	-	173
Red Globules of, -		-	- 173
Serum of,	-	-	171
Bones of Tympanum,		-	- 431
Brachial Artery, Branches of,	-	-	210
Broad Ligaments of the Uterus,		-	- 110
Brain, -	-	-	334
Veins of, -		-	- 384
Carotids, Branches of,	-	-	193
Capillaries,		-	- 153
Caul, Situation of,	-	-	8
Caecum,		-	38
Cerebellum, -	-	-	351
Cerebrum,		-	- 324
Chambers of Eye,	-	-	422
Choroidea,		-	- 405
 
INDEX.
521
                                                     Page
     ,  m                           .      - Vol. II. 442
Chorda Tympani,      -                        .24
Chylopoietic Viscera,       -                             J8
              —   Assistant,        -                  g_
Cilia,       -              "  ..  ..."    c                071
Circulation of the Foetus, Peculiarities ol,     -    ,      ~<
                        Peculiarities of, connected  with
                          its Nourishment, - -       -   276
                                                      147
Circulatory System,        -      -                    -._
           General Anatomy of,                        "'
                   Considerations on,    -      -      ™
            Special Anatomy of,       -      -       -   *4°
Clitoris,    -                                           g*r
Coccygeus,     -      -                        _      436
Cochlea,   -                                           30
Colon,  -      -      -                        _,      3-.Q
 Commissura Anterior,      -       -                     * Q
 Conjunctiva,    -      -                                „„
 Corona Glandis,    -      -                            .„.
 Cornea,         -                                      361
 Corpus Callosum,   -      -              -       "
         Cavernosum,    -      -       -             '   Jnt
         Ciliare,     -      -       .-       -       -      **
         Dentatum,      -      -       -      -      '   ut
         Fimbriatum,        -                           1*~
         Spongiosum,   ,.....»2
            —     Vaginae,        -      -      -      105
  Corpora Striata,        -----  359
  Crura Cerebri,      -      -             -      -     35?
  Couper's  Glands,       -       -       -       -       -   86
  Coronary Arteries,  -      -      -      -      -      187
           Veins,       -----   188
  Cremaster Muscle,  -----       92
  Cricoid Cartilage,      -      -      -      -      -   122
  Crico-Arytenoideus Posticus,      -      -       -      126
                    Lateralis,   -      -      -      -   126
  Crico-Thyroideus,   -       -      -      -       -      126
  Dartos Muscle,        -----    88
  Ductus Ejaculatorius,      ....       85
         Lactiferi,       -      -      -      -      -   117
  Duodenum,  -      -       -      -       -       -       33
  Dura Mater,    ------   335
             Sinuses of,     -       -       -       -      338
  Ear,     -      -      -      -      -      -      -   423
  Eminentiae Mammillares,-         -       -       -      357
             Olivares,   -----   347
  Epididymis,         -       -       -       -       -       91
  Epiglottis,       -       -      -       -       -      -  124
  Erector Clitoridis,   -----      102
         Penis,   -                                   -   95
     Vol. II.                  66 
522
INDEX
                                                     Page
Eustachian Valve,      -                       Vol. II. 179
           Tube,   -      -      -      -      -      430
External Iliac Artery, Branches of,    -       -      -   233
Eye,               .....385
Eye-ball,        ------   402
Eye-lids,    ------      386
Fallopian Tubes,       -       -       -       -          112
Fcetus, peculiarities of, arising from want of Respiration,  272
Fornix,  -------   362
Fossa Navicularis,  -----       83
      Ovalis,    -      -       -       -       -      -   179
Fourchette,  ------      101
Fourth Ventricle,       -       -       -       -      -   370
Fraenum Penis,     -----       80
Frontal Nerve,  ------   458
Fundamental Portion of Cerebellum,       -       -      354
Ganglion Cavernosum,   -----   481
         Cervicale,        -                           482
         Lumbar,      -       -       -       -      -   491
         Lenticular,       -      -      -       -      456
         Spheno-Palatinum,    -       -       -          453
         Sacral,.....492
         Thoracic,      -       -       -       -      -   486
Gall Bladder,              -      -      -       -       53
Glandulae Odoriferae Tysonii,   -       -       -      -    80
Glandulae Pacchioni,       ...       -      339
         Palpebrarum,        -                        389
Glandula Pinealis,  -----      364
Globus Major,   ------    91
       Minor,      -----       91
Head  and Neck, Veins of,                              248
Heart,      ...---      177
      Right Auricle of,  -       -       -       -      -   178
       —  Ventricle of,   -      -      -       -      180
      Left Auricle of,   -       -       -       -  ■    -   182
      —  Ventricle of,                                183
      Blood Vessels of  -       -       -       -      -   187
      Texture of,   -----      186
Hymen,         -       -       -       -       -          106
Ileo-Colic Valve,   -                                    39
Ileum,  -       -                                       34
Incus,      ------      431
Internal Iliac Artery, Branches of,     -       -       -   227
Inguinal Glands,   -----      296
Intestinal Canal,       -       -       -       -       -    29
Intestine, Small,   -       -      -      -      -       29
         Large,       -       -       -       -       -    35
         Small, situation of,                              8
         Large, situation of,   -       -       -  .  ■   -     8
Iris.                                    -    "  .      410 
iNDEX.
459
395
121
                                                    Page
                                          -  Vol. II. 34
3ejunum,      -                 ...       67
Kidneys,   -                                      -     9
        Situation of,   -      -                        6Q
        Minute Structure of,             -       "       J()2
Labia Interna,        -                        _       jqj
      Externa,     -       -                        _   434
Labyrinth,     -      -                               gn<2
Lachrymal  Apparatus,     -                            394
           Caruncle,   -      -      -       "   _       gg3
           Ducts,  -                                  392
           Gland,      -                               AKn
           Nerve,  -
           Sac,        -       -      -       -
Larynx,
Lateral Ventricles,    -       -      -       *       "or
Levator Ani,      ...
t                           -                        418
Lens,  -                                            40„
Ligamentum Ciliare,      -
             Denticulatum,    -      -       -       'tit
             Palpebrale Internum,       -      -       38°
 Liver,  -      -      -       -       -       -       "48
      Organization of,                                   °*
      Situation of,             -      -       -            8
 Lower Extremity,  Veins of,        -      -      -       261
 Lungs, -------   l38
      Texture of,   -      -       -      -      -       140
 Lymphatic Glands,    -----   286
 Malleus,......431
 Meatus Externus,          ,  -       -      -       -   423
 Mediastinum Anterior,    -                           144
             Posterior,       -      -      -      -  144
             Superior,    -              -      -      145
 Medulla Oblongata,    -      -       -      -       -   346
         Spinalis,  Nerves of,       -       -      -  323-493
 Membrana Pupillaris,  -      -       -             -   422
 Membrana Tympani,       -       -       -      -      428
 Membranous Labyrinth,       ...       -   437
 Mesentery, ------        35
 Mitral  Valve,   ....      -       -   183
 Mons Veneris,     -      -       -             -       100
 Mucous Glands, and Apparatus,       -      -      -     84
         Membranes, General Anatomy of,       -        41
 Musculus  Anterior Auriculae,  -                       427
           Antitragicus,    ....      426
           Attollens Auriculae, -                       427
           Corrugator Supercilii,    -       -      -      000
           Helicis,     -      -  •     -      .      .  426
           Laxator Tympani,       -       -      -      433
           Levator Palpebrae,   -      -      -      -  389 
524 INDEX.			Page
Musculus Obliquus Oculi Superior, — — Inferior, -	- Vol	.11	. 391
	-		391
Orbicularis Palpebrarum,	-	-	387
Rectus Oculi Superior, -	-		390
— — Externus,	-	.	390
— — Inferior,	-		390
— — Internus,	-	.	390
Retrahens Auriculae,	-		427
Stapedius,	-	-	433
Tensor Tarsi,	-		396
— Tympani,	-	-	433
Tragicus,	-		426
Transversus Auriculae,	-	-	427
Nervous System,	-		313
General Anatomy of, -	-	-	313
Nasal Nerve, -	-		457
Nerves of Brain,	-	•	371
Ear,	-		440
Nervus Abdomino-cruralis,	-	-	509
Accessorius,	-	372-471	
Auditorius,	-	-	374
Cervicalis, - - -	-		494
Circumflexus, .	.	.	500
Cruralis Anterior,	-		511
Cutaneus Externus,	- .	.	500
— Internus, -	-		500
— Femoris Externus,	-	-	510
— —- Internus,	-		511
— — Posterior,	-	.	513
Descendens Noni,	-		470
Fascialis,	- 374_44l_468		
Glosso-Pharyngeus, -	-	373-473	
Gluteus,	-	.	512
Hypo-Glossus,	-	371-470	
Infra Maxillaris,	-	.	464
— Orbitalis,	.		460
Ischiadicus,	-	.	512
Laryngeus Inferior,	-		477
— Superior,	-	-	476
Maxillaris Superior,	-		459
Medianus,	.	.	503
Motor Externus,	-		375
— Oculi,	.	.	378
Nasalis Internus,	_		452
Naso-Palatinus,	.	.	453
Obturatorius,	_		511
Olfactorius,	.	379-450	
Opticus, -	.		378
Patheticus,	_	_	377
Peroneus,			
 
INDEX.
525
                                                     Page

Nervus Petrosus Superficialis,  -      -      - VoL*   *
          —    Profundus,       -
       Pharyngeus Superior,  -      -                 ^
       Phrenicus,  -      -                           g.g
       Plantaris Externus,    -
          -     Internus,        -       -       "
       Pneumogastricus,       -       -            *"   ^
       Portio Dura,       -
         —   Mollis,   -       -       -       '      "515
       Popliteus,   -                                  _-
       Pudendalis Superior,   -       -       -      'A*
       Ptervgo-Palatinus,  -                           401
Scapuhtris,     -      -      -       "       "   t?n
Spermaticus Externus,      -      -             »*"
Splanchnicus,
       Subcostalis,        -      -      -      "      505
       Suboccipital,  -       -      -      -      "400
       Subscapularis,     -      -      -             *j|jj
       Sympatheticus,  -                           -   4«U
       Trigeminus,       -                       li'Jli
       Thoracicus,     -                           500-505
       Tibialis Anterior,  -                           515
       Trochlearis,    -       -      -      *      "     !
       Ulnaris,.....„  504
       Vidianus,      -                           462-443
Neurilemma of Nerves,     -       -       -       -      315
Nose,.......444
      Blood vessels of,     -       -       -       -      4i>4
      Nerves of,       -                              450
Omenta,     ------        18
Omentum Cohcum,      -      -      -      -      "on
          Gastro-Splenicum,       -                      20
          Mijus,  or Gastro Colicum,   -      -      -    19
          Minus or Hepatico Gastricum,   -       -        18
Ophthalmic Nerve,      -----   457
Optic Nerve,       -----       378
Orbit,  Arteries of,                                     398
       Nerves of,    -      -       -       -       -       398
       Veins of,......401
Os-Orbiculare,      -      -       -       -       *       432
Organs of Assimilation, -----     5
          Generation,      -                            79
              —     in the Male,     -      -       -    79
              —          Female,       -      -       100
          Respiration,  -----   121
 Os Tincae,   -.....108
 Ostium Venosum,      -      -      -      -       -   183
 Ovaries,     -      -      -      -      "      "      H^
 Pancreas,     -        -----    65
          Situation of,                                   9 
526                       INDEX.

                                                      Page
Pancreas, Minute Structure of,        -      -  Vol. II. 66
Papilla,......H9
Pelvic Fascia,   ------   99
Penis,.......79
Pericardium,    -      -      -      -             -  184
Perineal Fascia,     "      ."       '       "       "       94
Perineum, Muscles and Fascia of,       -                 94
Peritoneum,  -                                   -       10
Pia mater,      ------  343
Pigmentum Nigrum,                                   408
Pituitary Gland,        -      -      -      -      -  358
          Membrane,                                  447
Pleurae,  -----             "  142
Plexus Brachialis,   -----      498
        Cardiacus,      -----  485
        Choroides,.....345
        Cceliacus,.....489
        Coronarius,  -----      489
        Hepaticus,.....489
        Ischiadicus,  -       -       -       -       "      512
        Lumbalis,       -       -       -      "       "  508
        Mesentericus Inferior,      -                    490
            —      Superior,   -      -      -       -  490
        Phrenicus,   -----      489
        Renalis,.....490
        Solaris,.....488
        Splenicus,     - -       -       -      -       "  489
 Plica Semilunaris,  -       -       -       -       -       394
 Pori Biliarii,     -                                   -    52
 Prepuce,    -      -       -             "               80
 Primitive Iliac Artery, Branches of,    -      -       -   227
 Processus Ciliaris,  -----       409
 Prostate Gland,  -       -       -       -       -       -    85
 Protuberantia Annularis,   -                           350
 Pulmonary Artery,      -       -       -       -       -181
 Rectum,    ------       40
 Renal Capsules,  ------    73
                    Minute structure of,   -      -       73
                    Situation of,       -       -       -     9
 Retina,......413
 Round Ligaments of the Uterus       -       -       -   110
 Sacculus Ellipticus,        -                           438
          Sphericus,     -----   438
 Sclerotica,  ------      403
 Scrotum,       -      -       -      -       -      -    87
 Semicircular Canals,       -                           435
 Seminal Vesicles,       -       -      -       -      -    84
 Senses,     -      -      -      -      -      -      385
 Serous Membranes generally,   -      -       -          1°
                    General Anatomy of,
13 
INDEX.
Septum Lucidum,
Sinuses of Valsalva,
          the Vertebral Column,
Sinus Cavernosus,  -
      Circularis,
      Lateralis,
      Longitudinalis,   -       -       -
      Occipitalis,
      Petrosus,         -
      Quartus,
Soemmering's Foramen,
Spermatic Chord,   -
Sphincter'Ani,   -
          Vaginae,   -
 Spinal Marrow,        -
               Vessels of,   -
               Membranes of,  -
               Nerves of,
 Spleen,          -
       Situation  of,
       Intimate Structure of,
 Stapes,      -      -      -      -
 Stomach,       -      -      -      -
 Situation of,        -
 Subclavian Artery, Branches of,
 Tarsi,      -      -      -      -
 Taenia Striata,
 Tela Choroidea,    -       -      -
 Testicles,       -
           Minute Structure of,
 Thalami Optici,        -
 Third Ventricle,    -
 Thymus Gland,        -
 Thyreo-Arytenoideus,
         Epiglottideus,   -       -      -
         Hyoideus,  -
 Thyroid Gland,        -       -      -
          Cartilage,   -       -       -
 Thoracic Aorta, Descending, Branches of,
          Ducts,    -
 Trachea,       -
 Transversalis Perinei, (Male,)
                 —   (Female,)
 Triangular Ligament of the Urethra,
 Tubuh Semimferi,      -
 Tuber Cinereum,
  Tubercula Quadrigemina,
  Tunica Albuginea,   -
         Hyaloidea,
         Vaginalis.   ... 
528
Tympanum,
Umbilical Artery,  .
          Vein,
Upper Extremity, Nerves of,
                  Veins of,
Ureter,
Urethra, (Male,)
         (Female)  .
Urinary Organs,
Uterus and its Appendages,
Vagina,
Valve of Vieussens,
Vasa Arteriarum,
     Efferentia,
     Recta,
     Vorticosa,
Vas Deferens,  .
Vena Azygos,
     Axillaris,
     Basilica,
     Cava Inferior,
      —  Superior,
     Cephalica  •
    Choroidea,
    Facialis,   •
    Femoralis,
    Hemiazygos,
    Iliaca Externa,
      —  Interna,
      —  Primitiva,
    Innominata,
    Intercostales Superior,
    Jugularis Externa,
        —   Interna,
    Lingualis,
    Mammaria Interna,
    Maxillaris  Interna,
    Mediana,
    Meseraica  Inferior,
        —     Superior,
    Occipitalis,
    Ophthalmica,  •
    Palatina Inferior, •
    Pharyngea,
    Poplitea,  •
    Portarum,
    Ranina,  •
    Sacra Media,  •
    Saphena Minor Externa,
       -■--   Magna In''Mm. 
IVDF.X.
529
Vena Splenica,
     Subclavia,
     Submentales,
     Temporalis,   •
         —     Superficialis,
     Thyroidea Inferior,   •
        —     Superior,
     Vertebral is,
Veins, Texture of,
Venae Capsulares,  •
     Diploicae,
     Emulgentes,
     Hepaticae,
     Lumbales,
      Phrenicae Inferiores,
      Spermaticae,
Ventricles of the Brain,
Verumontanum,
Visical Triangle,
Vestibulum of Vulva,
           of Ear,
Vitreous Humour,
Vulva,   .
Willis, Circle of,   .
Page
 269
 261
 249
 250
 250
 254
 249
 254
 248
 268
 250
 268
 268
 266
 269
 267
 366
  85
  76
 103
 435
 416
 100
 384
rift: kv]i
Vol.  II,
67 
 
 
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