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HUMAN ANATOMY. 
I
<
f 
INTRODUCTION
STUDY OF  HUMAN  ANATOMY.

                  By JAMES PAXTON,
MEMBER OF THE ROTAL COLLEGE OF SURGEONS, HONORARY MEMBER OF THE
    ASHMOLEAN SOCIETY, AND AUTHOR OF NOTES AND ILLUSTRATIONS
                TO PALEY'S NATURAL THEOLOGY.

            IN TWO VOLUMES, WITH ILLUSTRATIONS.
Formative fibres of the Brain.  See page 13-M*
VOLUME
     SECOND AMERICAN EDITION, WITH  ADDITIONS,
             By W1NSLOW LEWIS, Jr. M. D.
DEMONSTRATOR OF ANATOMY TO THE MEDICAL DEPARTMENT"*^ HARVARD
                                        tfr* ;t. or $&
UNIVERSITY.
         BOSTON:
WILLIAM  D.TICKNOR
    Corner of Washington and School Streets.
          M DCCC XXXV.

<Lt>,
IW 
   Entered according to  Act of Congress in the year 1835,
               By William  D. Ticknc^
In tlie Clerk's office of the District Court of Massachusetts.
?3fU.
        boston:
tuttle and weeks, printers,
      No. 8, StiKK)! Street. 
CONTENTS.
       CONTINUATION OF ARTICLE V. —VASCULAR SYSTEM


                      CHAPTER  II.

Of  the Veins in General,
Structure of Veins,   .....
General Department of the  Venous System, .
  Veins which form the superior vena cava,
  Veins which give rise to the external jugular,
  Veins which give rise to the internal jugular,  .
  Veins forming the subclavian veins,
  Sux erior vena cava,   ....
  Veins forming the inferior vena cava,
  Veins forming the internal iliac vein,  .
  Common iliac veins,       ....
  Inferior vena cava,     .....
  Branches of the inferior vena cava,
  Vertebral sinuses and veins of the spinal marrow,
  Veins of the heart,   .....
  Coronary Veins,        ....
 A  nominal  Department of the Venous System,
  Vena Portre — Branches of, 
VI
coj\tj;vi>
CHAPTER  III.
Of  the Capillaries,
Page.
  21
                    ARTICLE  VI.

             ORGANS  OF  ABSORPTION

                      CHAPTER I.

Lymphatic Glands,       .....      22
Structure of the Lymphatic Vessels,     .      .      .24
Lymphatic Glands in General,   ....      24
Lymphatic Glands in Particular,   .      .      .      .25
  Lymphatic glands of the inferior extremities,   .      .      25
  Lymphatic glands of the pelvis,      .      .      .      .26
  Lymphatic glands of the abdomen,      ...      26
  Lymphatic glands of the thorax,     .      .      .      .27
  Lymphatic glands of the superior extremities,   .      .      27
  Lymphatic glands of the head and neck,    .      .      .28

                      CHAPTER  II.

Particular Lymphatic Vessels, ....      29
Lymphatic Vessels  terminating in  the Thoracic Duct,   29
  Lymphatic vessels of the inferior extremities,    .      .      29
  Lymphatic vessels of the perinseum, loins, etc.,     .      .   31
  Deep seated obturator, ischiatic and genital lymphatic vessels,  31
  Lymphatics of the urinary organs,    ...         32
  Lymphatics of the parietes of the pelvis and abdomen,  .      33
  Lymphatics of the stomach and intestines,   .      .      .34
  Lymphatics of the spleen, pancreas and liver,    .      .      33
The Thoracic Duct,  .....         37
  Lymphatics which open directly into  the thoracic duct,  .      38 
CONTEiNTS
  Lymphatics of the lungs,     ....
  Lymphatics of the diaphragm, heart, thymus and cesoph
  Lymphatics of the superior extremities,
  Lymphatics of the anterior parietes of the thorax,
  Lymphatics of the posterior region of  the neck and thoi
  Lymphatics of the axilla,  ....
  Lymphatics of the head and anterior part of the neck,
  Deep lymphatics of the head and neck,  .
  The office of the lymfjhaties and their  glands,


                  ARTICLE  VII.

               NERVOUS  SYSTEM

                      CHAPTER  I.

General Divisions of the Nervous System,
Cerebral Department of the Nervous System,
  The brain  in general,    ....
  The exterior of the cerebrum,
  The exterior of the cerebellum,
  The exterior of the pons Varolii,
  The medulla oblongata,   ....
  The medulla spinalis, .....
  The internal organization of the brain,
  Chemical analysis of the brain,
  Parts observed in the lateral ventricles,
  The internal structure of the cerebellum,

                      CHAPTER II.

The Membranous Envelopes of the Brain,
  The dura mater,      .....
  Sinuses of the dura mater,
  The arachnoid membrane,    .... 
viii
CONTENTS
81
82
83
                                                          Pag».
  The pia mater,     .      .       .       •      •       •       '"
  Granulations of the membranes of the brain,
  The proper membrane of the spinal marrow,    .       •       81
  Ligamentum denticulatum,   .
The Nerves in General,
Nerves of the Cerebral Department,
  Olfactory,  ....••       83
  Optic,   ......••   84
  Motores oculorum, ....••"•'
  Pathetic,      ......   86
  Trifacial,   .....-•       86
           1. Opthalmic branch,              .       •          87
           2. Superior maxillary,   ....       88
           3. Inferior maxillary,        .      •       •       .88
  Abducent,  .......      91
  Facial,  ........   91
  Auditory,  .......      94
  Glosso-pharyngseal,   .              .      .       .       .94
  Pneumo-gastric,   ......      95
  Hypoglossal,   .      .       .       .      .              .97
  Spinal accessory,  ......      98
  Spinal nerves,  .......   100
  First pair of cervical,      .....      100
  Second pair of cervical,      .....   101
  Third and fourth pair of cervical,        .             .      101
  Cervical plexus,      ......   101
  Fourth, fifth, sixth and seventh pairs of cervical nerves,       103
  Brachial, or axillary plexus,   .....   103
  Thoracic branches,       ....             104
  Nerves of the arm,   ......   104
  Internal cutaneous nerve,        ...      104
  External, or musculocutaneous,                            105
  The median nerve,       .                                 J07
  The ulnar nerve,     .       .                              jQg
  Radial nerve,                                             jqq 
CONTENTS.
ix
                                                         Page,
  Circumflex nerve, .       .      .       .      .      .     110
  Dorsal nerves, .......  110
  Lumbar nerves,   .       .      .       .      .      .     Ill
  First lumbar,  .      .       .      .       .      .      .111
  Second lumbar,   ......     112
  Third lumbar,.......112
  Fourth and fifth lumbar,   .....     112
  Lumbo-abdominal, or lumbar plexus,       .      .      .  113
  Musculo-cutaneous branches,    ....     113
  Genito-crural nerve,   .       .      .       .      .      .114
  Crural nerve,      .       .      .       .      .           114
  Obturator nerve,      ......  115
  Lumbo-sacral nerve,      .      .       .      .      .116
  Glutaeal nerve,  .......  116
  Sacral nerves,     .       .      .       .      .      .116
  Sciatic nerve,   .      •       .      .       .      .      .117
  External poplitseal nerve,  .      .       .      .      .117
  Internal poplitaaal nerve,      .....  118

                      CHAPTER III.

Ganglionic Department of the Nervous System,     .     120
Particular Ganglia,  ......  122
Ganglia of the Head,     .....     122
  Lenticular ganglion,  ......  122
  Spheno-palatine ganglion, .....     122
Ganglia of the Neck,        .....  125
  Superior cervical ganglion,      ....     125
  Middle cervical ganglion,     .....  126
  Inferior cervical ganglion,       ....     126
  Cardiac nerves,      ......  126
  Cardiac plexus, or ganglion,     .      .      .      .127
Thoracic Ganglia,    .......  128
  Splanchnic nerve,        .....      128
   VOL. II.                   A 
X
CONTENTS
Page.
 128
 129
 129
 129
 130
 131
 131
  Great splanchnic nerve,      .
  Small splanchnic nerve,   .
Ganglia of the Abdomen,     .
  Semilunar ganglia and solar plexus,
  The lumbar ganglia,  .
  The sacral ganglia,       .
  Hypogastric plexus,  .
Great Sympathetic Nerve,      •                         ™o
Formative Fibres of the Brain, according to Gall and
      Spurzheim,     ..••••   I***
                 ARTICLE  VIII.

        PARTICULAR ORGANS OF SENSATION.

                      CHAPTER I.

The Eye and  its Appendages,   ....     137
  Eyebrows,    .......  137
  Eyelids,   .......     138
  The globe of the eye in general,    ....  140
  The sclerotica,    ......     140
  The cornea,   ......       .140
  The choroid membrane,  .      .      .      .       .     141
  The ciliary circle, or ligament,      ....  142
  The iris,   .......     143
  The retina,    .       .      .      .      .      .       .144
  The aqueous humour,    .....     146
  The crystalline lens,   ......  147
  The vitreous humour,    ....            148

                      CHAPTER  II.

The Ear and its Appendages,  ....     150
  The external ear,     ••••..  150
  Fibro-cartilage of the ear, .                               152 
CONTENTS
 The auditory canal,  .
 The internal ear,  ....
 Bones of the ear,
 The labyrinth,    ....
 The cochlea, ....
 The semicircular canals,  .
 Auditory nerve,
 Mechanism of hearing,   .

                    CHAPTER III.

The  Nose,    ....
  Mechanism of smell,

                    CHAPTER IV.

The  Tongue, ....
  Taste,    .....

                    CHAPTER V.

The  Skin,     ....
  The dermis,     ....
  The rete mucosum,  .
  The epidermis,   .
  The sense of touch, .
The Hair,   .
  Organization of the hair,
The Nails,  .

                    CHAPTER VI.

Muscular Sensation,

                    CHAPTER VII

Visceral Sensation, 
Xll
CONTENTS
                   ARTICLE  IX.

             organs  of

The Mouth,
The Palate,
The Pharynx,
The CEsophagus,
The Stomach,
  Organization of the stomach,
  Office of the stomach,
The Intestinal Canal,
  The small intestine,
  The duodenum,
  The jejunum and ilium,
  The large intestine,
The Mesentery,
Digestion,  ,


                    ARTICLE  X.

            organs  of  respiration.

 The Lungs,......207
  Organization of the lungs,   .....   210
 Changes which take place in Respiration,  .      .      212
 The Trachea and  Bronchi,        ....   215
   Organization of the trachea and bronchi,      .      .      217


                    ARTICLE XI.

               ORGANS  OF THE  VOICE.
DIGESTION.
                         Page.
                       •   185
                          186
                       .   187
                          I88
                       .   190
                          191
                       .   193
                          193
                       .   194
                          194
                       .   195
                          197
                       .   202
                          203
The  Larynx,  .
  Cartilages of the larynx, . 
CONTENTS.
xiii
	Page.
Thyroid cartilage, ....	. 219
Cricoid cartilage,	220
Arytenoid cartilages, ....	. 221
Epiglottis, ...	222
The ligaments of the larynx,	. 223
The muscles of the larynx,	224
Crico-thyroideus, ....	. 224
Crico-arytenoideus posticus,	225
Crico-arytenoideus lateralis, .	. 226
Thyro-arytenoideus,	226
Arytenoideus, ....	. 227
Mucous membrane of the larynx,	227
The gland of the epiglottis, .	. 227
The arytenoid glauds,	228
The office of the larynx,	. 228
The thyroid gland,	229
                  ARTICLE  XII.

            organs  of  secretion.

Organs for  the Secretion and Transmission of Tears,   230
  The lachrymal gland,      .....   230
  The caruncula lachrymalis,      ....      231
  The puncta lachrymalia,    .....   231
  The lachrymal sac,      .....      232
  The nasal duct,     .      .      .      .      .      .232
The Salivary Glands,    .....      232
  The parotid gland,   ......   233
  The submaxillary gland,        ....      234
  The sublingual gland,      .....   234
The Pancreas,   ......      235
Organs for  the Secretion and Transmission of the Bile, 236
  The liver,.......236 
\iv                     CONTENTS
Page.
 238
 239
 239
 240
 240
241
242
  Ligaments of the liver,   .       .      •       •       •
  Envelopes of the liver,      ....
  The hepatic duct,       •
  The gall bladder,    .
  Cystic duct,     .      .       .      .       •
  The ductus communis choledochus,
  Secretion of bile, ..-••■
The Spleen,   ...•••
  Organization of the spleen,      .                          ^4c*
  Office of the spleen, ...•••   243
Supra-Renal Capsules,  .                                 245
The Kidneys,  ....•••   245
  Organization of the kidneys,    ....      246
  The calyces, pelvis, and ureter,      ....   247
The Bladder,    ......      250
  The organization of the bladder,    ....   251
  The office of the kidneys and bladder,  .       .       •      252
  The urine,    .......   253
                  ARTICLE  XIII.

      ORGANS  OF  GENERATION  IN  THE  MALE.

The Testicles and their Appendages,   .      .       .   255
  Envelopes of the testicles,       ....      255
  The testicles, .......   256
  Organization of the testicle,      ....      257
  Epididymis,  .......   258
  Vas deferens,     ......      258
  Spermatic cord,      ......   259
  Vesiculse seminales,     .....      260
  Prostate gland,       ......   261
  Cowper's glands,        .                                262
  Ejaculatory  ducts,   ......   262 
CONTENTS
XV
	Page.
ENIS, ......	264
Integuments of the penis and prepuce,	. 264
Corpus cavernosum, ....	264
Organization of the corpus cavernosum,	. 265
Urethra, ......	266
Organization of the urethra, .	. 267
Glans penis, .....	268
                 ARTICLE  XIV.

 organs of generation,  etc.  in the  female.

Organs of Generation, and for the Nutrition of the
      Child, in the Female,       ....   269
Organization of the Vagina,   ....      271
The Uterus and its Appendages,   ....   272
  Organization of the uterus,     ....      273
  The broad ligament,  ......   276
  The round ligaments,    .                              276
  The Fallopian, or uterine tubes,    ....   276
  The ovaries,     ......      277
  The gravid  uterus,   ......   280
  Developement of the ovum in the uterus,      .      .      282
Membranes which inclose the F<etus,    .      .      .   283
Liquor Amnii,     ......      284
The Placenta,       .      .      .      .      .      .284
  Office of the placenta,   .....      287
Funis Umbilicalis,   ......   287
Umbilical Vesicle,      .....      288
TheMammje,  .......   289
  Organization of the mamma?,   ....      289
  Office of the mamma?,      .....   291 
XVI
CONTENTS
                  ARTICLE  XV.

                     the fg3tus

Peculiarities of the F(etus,


                 ARTICLE  XVI.

     SEROUS SYSTEM AND CELLULAR TISSUE.

The Pleura and the Peritoneum, .
Omenta, or Epiploa,
Cellular Tissue, &c. .
Fat,      ....
Page.
 293
304
308
311
314 
          ANATOMY

                 OF

THE   HUMAN  BODY.
                      CHAP. II.

              OF THE VEINS  IN  GENERAL.

  It has been already stated,  that it  is the office of the
arteries to convey the blood from  the heart to the different
parts  of the  body,  for  the  purpose  of nourishing and
building up the animal  fabric: now  there  is  a corres-
ponding  series of  sanguineous  canals which  return the
blood from all  the organs,  again to continue the stream of
the circulation; these are the veins.  By  the aid of a
microscope, the extreme branches of the  arteries may be
observed communicating with  the minute radicles of the
venous system, and  transferring their blood to that  series
of vessels.   The  curious and beautiful phenomena of the
circulation  are evident, when the  tail of a fish, or the web
of a frog's  foot, is placed in the field of a  powerful magni-
fier ; and we are assured of the  fact of the continuity of
the two sets  of vessels in  the  human  subject,  by the
circumstance of fine injections passing readily from the
arteries into the veins.
  There are two departments of the venous system : the
1st, or general department of the venous system, more ex-
tensive than the other, commences in the  head, trunk and
   VOL. II.              1 
2
VASCULAR SYSTEM
limbs, and  transmits the blood to the heart by the venae
cava?.   The  2d, or abdominal  department of the  venous
system,  is confined to  the  cavity of the  abdomen,  and is
formed by the veins of  all the chylopoetic viscera, with  the
exception of  those of the liver,  and terminates in the vena
porta?, which subdivides and distributes the blood through
the liver.
  The veins are far more numerous, and, considered as a
whole, they are much more capacious than the arteries.
  The distribution of veins is somewhat similar  to that of
the arteries, but their  number  and size  are  greater.   In
general  a cellular  space, common to all, receives both  the
trunks of the two species of  vessels  and  those of  the
nerves.   In the head,  limbs, and  every other part, there
are two sets of  veins;  the superficial and  the deep seated:
the 1st  lie  immediately under  the  skin, or run  above  the
fascia?, and  are in some parts very large and numerous and
do  not  possess any corresponding arteries.   The  2d, or
deep seated veins,  directly attend the arteries.  The union
between the  branches  of the veins is very frequent; they
communicate in right  lines  or  in  arches, and the smaller
are so multiplied  as to form complicated meshes of net-
work ;  but  the  minute ramifications of veins ultimately
form an inconceivable number of small canals in  the tissue
of organs, of such  extreme tenuity, as to render it  impos-
sible to  understand their final distribution.


                 STRUCTURE OF  VEINS.

  The veins are formed of only  two membranes ;  the outer
is composed of  longitudinal fibres, very easily distinguished
in the large trunks, and surrounded by a sheath of cellular
tissue, the layers of which are placed very densely on each
other.   The  inner membrane is thin, smooth, and glossy ; 
OF THE VEINS.
3
and in appearance resembles the membrane which lines the
arterial tubes, but it is more extensible and less brittle.
  Valves  are formed in the general department of  the
venous system,  but  there  are  none  in the  system of the
vena  portae,  the  umbilical vein, the  trunk of the inferior
cava, in the veins of the brain, of the vertebra?, of the spinal
marrow, of the heart, of the kidneys and of the uterus.
There are but very few  in the vena azygos, and pulmonary
veins.  These  valves  consist of  a number of semilunar
folds of the inner membrane of the vein, precisely similar
to  those which  exist at the commencement of the aorta
and the pulmonary artery.
   The valves  are sometimes  single; they are,  however,
more frequently arranged in pairs, at other times there are
three together.  Apparently, their office is to support the
column of blood, and to prevent its return by the veins from
the heart  to the  surface of  the body;  for the  valves are
 pressed close to the sides of  the vessels during its flow to-
 wards the heart, but they are raised when the blood, from
 any accidental circumstance, is  disposed to pass in a retro-
                            grade  direction.   Fig.  1 re-
                            presents a vein laid open, thus
                            shewing the  single, duplex
                            and triplex valvular appara-
                            tus.
                               The veins are supplied by
                            very minute   nutrient  ves-
                            sels (vasa vasorum) and nerv-
                            ous filaments, which ramify in
                            the  cellular membrane, and
                            which penetrating the venous
                            tissue, finally terminate in the
                            inner surface of the vessels.
                               Veins may be distinguished
                             from  the   arteries  by  their
                             membranes being much thin-
 
4
VASCULAR SYSTEM
ner, by their greater number and size, by their having no
pulsation, by the dark color of the blood they contain, and
in many instances  by the peculiarity of their numerous
valves.

    GENERAL DEPARTMENT OF THE VENOUS SYSTEM.

I.  VEINS WHICH,  BY THEIR UNION,  FORM  THE EXTERNAL
                 SUPERIOR VENA CAVA.
                          Fig. 2
   1. VEINS WHICH GIVE RISE TO THE EXTERNAL JUGULAR VEIN.

  The internal maxillary vein commences in all the parts
to which the artery of the same name is distributed ; it is
consequently composed  of  the pterygoid, spheno palatine,
alveolar, infra-orbitar, mental, inferior  dental, and deep 
OF THE VEINS.
5
temporal veins.  It communicates with the sinuses of the
base of  the  skull by means of small twigs  which  pass
through  the  foramina of that region.  Upon  the  side of
the neck  the  internal maxillary vein frequently communi-
cates with the facial and  pharyngeal veins.  This disposi-
tion produces the pharyngeal plexus.
   The superficial temporal vein, g, commences in all those
parts where  the corresponding artery is  distributed.  It
is composed of the middle  temporal vein, f the  anterior
auricular veins, and the transverse veins of  the face.  Thus
formed it descends before the ear, and unites with the  pre-
ceding.
   The vein which results from this  union passes  through
the parotid gland, communicates with the  internal jugular
vein, and receives the following :
   The posterior auricular vein, which collects the blood
from the mastoid region and from the ear.  The trunk
then takes the name of
   The external jugular vein; it extends from d to c, and is
placed between the sterno-cleido-mastoideus and  the  pla-
tysma  myoides muscles.  In its course along the neck it
receives the following:
   The cervical cutaneous, the trachelo-scapular, and other
veins which arise in the vicinity  of the neck and shoulder.
At the inferior part of the neck the  external jugular opens
near c  into b, the superior part of the  subclavian vein, a
little on the outer side of a,  a, the internal  jugular vein.

   2.  VEINS WHICH GIVE RISE TO THE INTERNAL  JUGULAR VEIN.

   The superior cerebral veins commence upon the convex
surface of the two  hemispheres of the brain, from  the
substance of which  they issue by a multitude of minute
branches, and are continued into the superior longitudinal
and lateral sinuses. 
6
VASCULAR SYSTEM
  The vein of the corpus striatum is  extended  over the
surface of that body, and, exactly following the course of
the tenia semicircularis, unites with the following :
  The veins of the choroid plexus, which return the blood
into the vena galeni, and from thence into the right sinus
of the dura mater.
  The  superior cerebellar veins  convey the blood  from
the whole  upper surface, and from  the  substance  of the
cerebellum, into the  torcular  herophili  and  the venae
galeni.
  The inferior cerebellar  veins unite on each side of the
cerebellum, and return their blood into  the corresponding
lateral sinuses.
  The lateral and inferior cerebral veins are very numer-
ous ;  they  unite on each side  and leave the brain to open
into the lateral sinuses.
  The ophthalmic vein commences from all  parts within the
orbit, and  unites on each side into three  or four trunks,
so that  this vein is  formed of the  lachrymal,  the central
vein  of the  retina,  the infra  orbitar, the ciliary, the
ethmoidal,  the palpebral, and  the nasal  veins.  The oph-
thalmic then passes  out of the orbit, by the inner part of
the sphenoidal  fissure, and  conveys  the  blood into the
cavernous  sinus.
   All the blood of the brain  is returned into the sinuses
of the dura mater, which terminate at the foramen  lacerum
posterius.   This point is  the  commencement of the jugu-
lar vein, and as it is  here considerably dilated, it is named
the sinus of the internal jugular vein.  This vein advances
a little forwards,  and  descends  with  the carotid artery,
covered by the styloid process of the temporal bone, and
by the muscles which are attached to it.  It communicates
 at first with the external jugular  vein, by a branch of large
 size,  and  at the level of the upper part  of the  larynx, it
 receives the facial vein. 
OF THE VEINS.
7
   The facial vein, e, commences  on the summit of the
head and forehead, and when  it has arrived at the side of
the nose, near the eye, it has the name of the angular vein,
and receives the blood from the ophthalmic, the palpebral
and the superciliary veins.  It  follows the direction  we
observe in  the figure, receiving the dorsal veins of the nose,
the superior and  the inferior coronary veins  of the lips,
and several buccal and masseteric  veins.  It is afterwards
augmented by the ranine, the  submental, and the inferior
palatine  veins, and then  becomes  united to the internal
jugular vein.
   A little below the facial vein, the internal jugular is aug-
mented  by the lingual and pharyngeal  veins: and at the
level with  the  superior edge of the  larynx, it receives the
superior thyroid, the  occipital,  and the veins of the diploe
of the bones of the skull.
   After receiving the above branches, the internal jugular
vein descends vertically at the side of the neck, and opens
into the  subclavian vein.


3.  VEINS  OF THE SUPERIOR EXTREMITY WHICH, BY UNITING, FORM
                THE SUBCLAVIAN VEINS, Fig. 3.

   The  collateral  arteries  of  the fingers, the radial  and
ulnar arteries, and all their divisions are each accompanied
by two venous  branches, which  become larger as they as-
cend toward the elbow joint, where they unite so as after-
wards  to constitute two large trunks, which run along the
brachial  artery  and  open into the axillary vein.  They
receive in  their  course  all  the veins  which  attend the
divisions of the artery.
   The  cephalic  vein commences  by a great number  of
branches, disposed in the form of a  net work, on the  back
of the hand  and upon the muscles of the thumb ; these
unite into  a trunk, which  ascends upon the anterior and 
8                 VASCULAR SYSTEM

external part of the fore-arm, where it forms the superficial
radial vein, and on arriving  at  the bend of the arm unites
with  the median cephalic vein, which communicates  with
the median basilic.
  The united  veins which form the trunk of the cephalic
ascend on the outer and  fore part of the arm, then bending
inwards, open into the axillary vein.
  The basilic vein  is larger than the cephalic, and is formed
of three branches, which are named from their situation,
the posterior  ulnar, the  anterior ulnar,  and the median
basilic veins. 
OF THE VEINS.
9
                                   The  basilic  vein  as-
                                cends on the inner part
                                of the  arm and unites
                                frequently, as at  e, with
                                the  cephalic vein.    It
                                then  passes into  the ax-
                                illa,  being   continuous
                                with the axillary vein.
                                   Fig.  3, b, the  axillary
                                vein.
                                   d,  the cephalic vein.
                                   c, the basilic  vein.
                                   /, the radial vein.
                                   g,  the  anterior ulnar
                                vein.
                                   The  axillary  vein  is
                                therefore  the   result  of
                                the union of the veins
                                of the  hand,  fore-arm
                                and  arm;  it  proceeds
                                obliquely under the  cla-
                                vicle, and in front of the
                                axillary artery,  and  be-
                                 comes  continuous with
                                 a, the  subclavian  vein.
                                 See  also, Fig.  4, t,  the
                                 axillary, and f the  sub-
                                 clavian veins.
                                   In  this  course it re-
ceives the circumflex veins, the inferior  scapular, the  long
thoracic, the superior thoracic, and the acromial veins.
  VOL. II.               2
 
10
VASCULAR SYSTEM
  The subclavian veins, Fig. 4, /, u, extend from the infe-
rior extremity of the scalenus anticus muscle to the supe-
rior vena cava, but they present differences  according as
they are  examined  on the right  or on  the left side, on
account of  the  position of,  g, the superior vena  cava. 
OF THE VEINS.
11
Thus the right subclavian vein, /, is  very short, and its
size is always less than that of the left.
  The  left  subclavian  vein, u, is much  longer than  the
right, and receives  two veins  which the  right does  not
receive  ; viz. the left internal mammary and the left inferi-
or thyroid.
  That part of the left subclavian vein nearest the descend-
ing cava,  which lies before the trachea, is generally known
as the vena innominata.
  The  two subclavian veins equally receive  besides  the
internal and the external  jugular veins, the vertebral and
the superior intercostal veins.
  The vertebral vein descends in the canal which contains
the vertebral artery, and issuing from  thence  at the sixth
or seventh cervical vertebra it unites with another consid-
erable vein, which communicates with  the lateral sinus of
the dura mater  by the mastoid foramen.   After this union
it receives numerous  branches from the adjacent muscles,
and opens into the subclavian vein.
  The right and left superior  intercostal  veins also dis-
charge their blood into the subclavian veins.


                SUPERIOR  VENA CAVA, g.

  The  superior vena cava  forms the grand trunk which
transmits  the blood  of  the  head, the  neck, the  superior
extremities,  and a portion of the circulation of the thorax,
to the heart.  This vein  commences opposite the cartilage
of the first rib, and descends to the  base of the pericardi-
um, from which it receives a fibrous sheath.   It then enters
that  membranous  sac, descends vertically on the right of
the aorta, and opens into the right auricle of the heart.
  Before  entering the pericardium  the superior vena cava
receives the following branches : — 
12
VASCULAR SYSTEM
  1st.  The right internal mammary vein, which differs from
the left only in its termination.
  2d.  The inferior thyroid vein, opening into the superior
vena cava, between the two subclavian veins.
  3d.  The vena azygos, Fig.              ^g-5-
5, a, a, a, is remarkable for
having  no   corresponding
vein, and in forming a com-
munication between the two
venae cavae.  It opens into
the superior vena cava im-
mediately above  the  right
branches,   and    passing
through  the  pillars of the
diaphragm, with  the aorta
and thoracic duct, opens in-
to the  inferior vena cava, or
into one of the lumbar veins.
  4th. The vena azygos at
the convexity of its  curve
receives the right bronchial
vein, and anteriorly branches
from the aorta and oesopha-
gus.  To the right it receives
the corresponding  intercos-
tal  veins.  To the left, to-
wards  the seventh rib, the
vena  semi-azygos, a  consi-
derable branch which ascends parallel to the vena azygos,
on the left side of the vertebrae, and which receives the in-
ferior intercostal veins of the left side.
 
OF THE VEINS.
13
II. VEINS  WHICH,  BY  THEIR UNION, FORM THE INFERIOR
                      VENA CAVA.

1. VEINS WHICH, BY THEIR UNION, FORM THE EXTERNAL ILIAC VEINS.

  The popliteal vein,  commences by three veins which ac-
company  the anterior, posterior  and fibular arteries ;  the
external saphena  vein also contributes to its formation, by
collecting the blood upon the  front  and outer  side of the
foot, and  passing  into the ham, opens into the popliteal
vein.
  The femoral or  crural vein is a continuation  of the pop-
liteal vein ; it ascends obliquely at the inner and fore part
of the  thigh, close to the femoral  artery, following  the
same  course up to the crural  arch.  In its progress it re-
ceives a great  number of deep branches,  precisely similar
to those of the artery, and the following remarkable super-
ficial branch: 
14
VASCULAR SYSTEM
  The internal vena
saphena, Fig. 6, col-
lects the blood from
the inner part of, a,
the foot and  toes ;
it  is united to  the
external saphena by
a transverse arch ;
these united branch-
es  ascend   before
the inner ancle, and
form a trunk which
is continued on the
inner  part  of  the
leg, and passing be-
hind the inner con-
dyle of the femur,
it  proceeds on the
inside of the  thigh
to an opening in the
fascia lata, b, where
it   discharges  itself
into, c, the  femoral
vein.  At this part
it   receives  several
superficial  abdomi-
nal veins,  the  cir-
cumflex  iliac  vein,
and  the   external
pudic veins.
   The external il-
iac   vein   receives
branches     corres-
ponding to the artery of the  same  name, and in the male
it receives a large vein which originates in the envelope of
the testicle. 
OF THE VEINS.
15
2. THE VEINS WHICH, BY THEIR UNION, FORM THE INTERNAL ILIAC
                          VEIN.

  The internal  iliac  vein,  Fig. 4, s, s, is  situated in the
cavity of the pelvis, behind the artery of the same name ;
its branches correspond exactly to those of the artery, with
the exception of the following :
  The vesical veins are large and very numerous, but differ
according to the sex of the subject we examine.
  In the male they commence  upon  the glands and unite
into two trunks, the  dorsal veins of the penis, which run
upon the back  of that organ,  and afterwards wind  down-
wards upon the organs of generation, and continuing their
course on the sides of the  bladder, and over the  prostate
gland, open into the internal iliac vein.
   In the female the vesical veins commence by the veins
of  the clitoris and the labia, and unite with the numerous
vessels of the vagina and rectum.
   The sacro-lateral veins,  communicate in the sacral canal
with the vertebral sinuses, and emerging from the anterior
sacral foramina  join the internal iliac vein.


                  COMMON  ILIAC  VEINS.

   The common  iliac veins result from the union of the  ex-
 ternal and internal veins ;  they extend from the sacro-iliac
 symphysis to the fifth  lumbar vertebra, where they give rise
 to  the inferior vena cava.


           INFERIOR VENA CAVA.  Fig. 4, 71, r.

   The inferior vena cava is larger than the superior, and
 extends from the articulation of the fourth and fifth lumbar 
16
VASCULAR SYSTEM
  vertebrae  to  the right auricle of the heart.   It ascends
  on the  right side of the bodies of the lumbar vertebrae,
  passes above and behind the liver, and advancing through
  a wide  aperture of  the  aponeurosis of the diaphragm, in-
  troduces itself into  the  pericardium, and  enters the right
  auricle of the heart by  an  aperture which  is  bounded by
  the Eustachian valve.


         BRANCHES  OF THE INFERIOR  VENA CAVA.

    The  middle  sacral vein  ascends  upon  the coccyx and
  sacrum, in the  angle  formed by the union of the common
  iliac veins.
    The lumbar veins are  four in number on each side, and
  commence by an abdominal branch, and a dorsal  branch,
  corresponding to the branches of the  lumbar arteries;  the
  dorsal communicates by the intervertebral foramina, with
  the vertebral sinuses.   The lumbar veins of the left  side
  pass under the aorta and are  in  consequence longer than
  the right.
    The spermatic veins, see  Fig. 4, r, differ in  their origin
  in the  two sexes.  In  the male they commence by  the
  spermatic plexus, the roots  of which are  expanded  in  the
  testicle, they anastomose with  the  neighboring veins, and
•  collect  into  four  or  five  branches, which envelope  the
  vas deferens, and passing through the inguinal ring, unite
  and form  a single trunk, which  extends upwards  and
  inwards on  the psoas muscle, as  far as  the upper part of
  the pelvis, where the spermatic vein forms another plexus
  named the corpus pampiniforme : these veins again unite
  and convey their blood  into the inferior  vena cava on the
  right side, and into the corresponding renal vein  on the
  left side.
    In the female, the spermatic veins originate in the ovari- 
OF THE VEINS.
17
urn,  Fallopian  tube, ligamentum  teres,  and sides of the
uterus;  they afterwards collect between the laminae of the
broad ligament of the uterus, and then follow the same
course as in the male.
   The renal veins, see Fig. 4, o, o, are of great size.   Their
roots exactly correspond  to the minute ramifications of the
renal arteries.  They unite in  the fissure of p, p, the kid-
neys, into several  branches, which collect into  a  trunk
opening into the cava.
   The capsular and adipose veins frequently open into the
renal veins, and in other respects have the same disposition
as the arteries  to which they correspond.
   The hepatic veins have their roots  in  the substance of
the  liver:  some of them are of small size and enter the
vena cava separately;  others, namely, the middle  hepatic
veins, open into the vena cava between  the right and left
hepatic veins.
   The middle hepatic veins open into the vena  cava be-
tween the right and left hepatic veins.
   The left hepatic veins ramify in the left lobe  of the liver,
 and proceed from thence into the vena cava, opposite  the
 aperture of the diaphragm, through which it passes.
   The right hepatic veins issue from the right lobe  of the
 liver, and open into the vena cava below the preceding.
   The  inferior  diaphragmatic veins  are  two in number,
 and are similar to the arteries of the same name.


 VERTEBRAL  SINUSES AND VEINS  OF THE  SPINAL  MARROW.

   There exist in the whole  length of the vertebral cavity
 two great venous canals, named  the vertebral sinuses, and
 which communicate with the internal jugular vein.  These
 sinuses have the same  structure  as the sinuses of the dura
 mater, in being traversed in various directions by irregularly
 distributed membranous bridles.
    VOL. II.             3 
18               VASCULAR SYSTEM

   At their inner side, they communicate with  each other
by transverse sinuses, occupying  the middle of the body of
each vertebra, then passing under the  posterior vertebral
ligament, they receive  the  veins which  transmit the blood
from the envelopes of  the  spinal marrow,  and the  spongy
tissue of the vertebrae.
   The veins of the spinal marrow accompany the arteries
of that name, and open into the inferior cerebellar veins.
   The veins of the sacral  canal  are of considerable size ;
they are immersed in cellular tissue, and have no adhesion
to the osseous parts.   Their inferior extremities are lost in
very delicate ramifications  upon  the os coccygis.  Exter-
nally, they form communications with the  lateral sacral
veins ;  and, internally, their transverse branches  anasto-
mose with each other.
                 VEINS OF THE HEART.

                    coronary veins.

  The great right coronary vein collects  the  blood from
the apex of the heart,  passes into the  groove which sepa-
rates the auricles  from  the ventricles, and  receives a great
number of lateral  branches which  terminate in the right
auricle, close by  the entrance of the  inferior  vena cava,
where  the coronary is covered by a  semilunar valve.
  The small right coronary vein unites with the preceding,
and passes in the same direction to  the posterior surface of
the heart.
  The  left  coronary  veins  are smaller than the  right.
They commence, with the preceding, at  the  apex of  the
heart,  by numerous roots, which unite, upon  the  convex
surface of that organ, into a single trunk, which discharges
its  blood with the  other veins at the posterior part of  the
right auricle. 
OF THE VEINS.
19
  There are a number of veins which terminate directly in
the cavity of the right side of the heart, by minute orifices,
which  have been  termed, by their original describer, the
foramina thebesii.


   ABDOMINAL DEPARTMENT OF THE VENOUS SYSTEM.

                     VENA PORTiE.

              BRANCHES OF THE VENA PORT.K.

   The vena porta  derives its blood from all the organs of
digestion in the cavity of the abdomen, excepting the liver.
It is formed principally by three large trunks, the coronary
vein of the stomach, the splenic and the mesenteric veins,
all which unite to form  the  middle  part or trunk of the
vena portae.
   The  coronary vein of the  stomach  corresponds to the
artery of the same name.  It is the  smallest of the three
branches.  It empties into  the  trunk  of the  vena portae,
behind  the pyloric portion of the stomach.
   The splenic vein collects  the blood from the spleen by a
number of branches, which,  after a short course, unite
upon the pancreas into a single trunk, which extends  from
left to right to  unite with the superior mesenteric vein, op-
posite the vertebral column.   It likewise receives the veins
which  correspond  to  the  vasa breviora, the right  and left
gastro-epiploic, the duodenal, and the pancreatic veins, and
the small mesenteric vein.   The  last named vein  receives
the blood from the left part of the colon and  the rectum.
Its branches correspond  to those of the inferior mesenteric
artery.
   The  superior mesenteric vein is distributed  in the same
manner as that of the  artery of the same name, to the
right, and a little  in  front, of which  it is placed.   It  is 
20
VASCULAR SYSTEM
formed by the veins of the small intestines, and by those
which correspond to  the right colic arteries;  and in the
mesentery it constitutes  a net-work, very  similar  to the
ramifications of the artery.  At the edge of the transverse
mesocolon, the trunk  of  this vein, after receiving  several
branches from the duodenum  and pancreas, unites with the
splenic vein.
   The trunk of the vena porta, is formed by the junction
of the splenic and superior mesenteric veins with the coro-
nary vein of the  stomach; it extends from the vertebral
column to the groove of the liver, and separating into two
branches, nearly at a right angle, seems to form under the
liver a horizontal canal, which has been termed the sinus of
the vena porta.   These vessels are  extended through the
lobes of the liver in innumerable ramifications.   In its pas-
sage under the small extremity of the pancreas, it is united
to the cystic and  hepatic  ducts, the  hepatic artery, and a
number of nervous filaments and lymphatic  vessels ; all
which  are  surrounded by a  fibrous  envelope named the
capsule of glisson.
   Injections thrown into the vena portae penetrate into the
other vessels of the liver, and vice versa. 
OF THE VEINS.                  21
                      CHAP.  III.

                 OF THE CAPILLARIES.

  The  delicate branches of the final ramifications of  the
arteries  and of the  minute  origins of the veins, are called
the capillaries.   In these small vessels most  of the  im-
portant  functions of life take place, as secretion, nutrition,
exhalation, calorification, &c.   They are of such extreme
tenuity  that  they  escape  detection by the  naked eye.
Their existence may be demonstrated  not only by micro-
scopical observation as observed in the last chapter, but by
the fact, that a colored fluid  may be  thrown  from  the
arteries  into the veins, without any extravasation between
them.
  There are two parts in  the capillary system.  One is
diffused over the whole body,  being placed  between  the
terminating branches of the arteries  and  the  roots of  the
veins, the other part is between the minute ramifications of
the pulmonary arteries and the origins of the pulmonary
veins.   In the first  the arterial blood is changed to venous ;
in the last, the reverse.  Their  intimate organization is
unknown.
  Though these  capillaries  exist everywhere in the body,
still they are more or less  numerous in the various organs.
They are more abundant in  the secretory organs, the skin,
the mucous membranes, and the lungs, and less so in  the
fibrous structures ;  in short the capillary system is as much
more developed in a part, says Bichat, as it has more func-
tions to sustain, and do not exist in organs  in proportion
to their  size, 
ART.   VI.
                      CHAP. I.


               ORGANS OF  ABSORPTION.

  The  organs  of absorption  consist of lymphatic vessels
and lymphatic glands;  the latter also are named lymphatic
ganglia.  This  system of vessels was perfectly unknown
until a  celebrated  anatomist of the name of Asellius, in
the year 1622,  discovered, upon the mesentery of a dog,
white lines extending from the intestine to the glands.  He
observed that they contained a milk-like fluid, and  hence
termed them  lacteals.   By a series of experiments he found
that  these vessels absorbed the chyle, and conveyed it to
the blood ; and subsequent inquiries proved that the same
system of vessels was minutely distributed over the whole
human frame; and that, at the angle formed by the union
of the subclavian with the internal jugular vein, upon either
side of  the neck, one or more of these  vessels discharges
their contents into the current of blood.
  The  lymphatic vessels are  small pellucid  tubes, which
occur in all parts of the body;  they originate on the sur-
face of  the membranes, and in  the tissue of all the organ-
ized  structures ; and they transport all the absorbed fluids
to the venous  system.  Those absorbents which take up 
LYMPHATIC SYSTEM.
23
the chyle in the intestines, during the process of digestion,
are named lacteals; and, although they differ in their uses
from  the other  absorbent vessels, they have precisely the
same  anatomical character.
  The ultimate arrangement of  the lymphatic vessels has
not been demonstrated, but the whole exterior of the body
is  known to be covered by a net-work of these vessels,
placed in the subjacent cellular tissue, and others occupy
the muscular intervals and organs of the body; nor is this
system of vessels confined to the limbs only,  for it exists
in the surface and  substance of  each particular  organ, as
in the lungs, liver,  spleen,  pancreas, and other viscera,
where both superficial and deep seated lymphatics are uni-
formly distributed.
  Generally these vessels are straight in their  course, but
their communications with each  other are  very numerous,
and  they frequently  form successive  meshes.  They are
also remarkable  for their alternate unions and divisions, so
that a great number of vessels, after being collected into a
single trunk, separate  a second time, and again form one or
more  trunks, which appear most conspicuous in  the vicinity
of their glands.


                   thoracic  duct.

  All the absorbent vessels discharge themselves into the
subclavian  and  internal  jugular veins, by considerable
trunks, called the thoracic duct, and great right lymphatic
duct.  These convey  the absorbed fluids into the circula-
tion.  See Fig. 5, d, the left, and /,  the right thoracic
ducts. 
24
LYMPHATIC SYSTEM.
        STRUCTURE OF  THE  LYMPHATIC  VESSELS.

  The lymphatic vessels are formed of an external cellular
membrane, and an  internal membrane  similar to  that of
the veins; the latter is folded upon itself, producing valves
at intervals, which are generally disposed in pairs.   These
valves are  usually more  numerous as the vessels diminish
in caliber.  So that the  thoracic canal contains fewer than
the others.


            LYMPHATIC  GLANDS  IN  GENERAL.

   The branches of the principal lymphatic  trunks traverse
a greater  or less  number of lymphatic glands; that is to
say, small bodies of various forms and size, and collected
together in greater or  less quantity, or sometimes isolated.
These glands are not numerous in the extremities, but they
occur abundantly in the  thorax and abdomen.  Each gland
receives lymphatic vessels, which subdivide and form  an
inextricable interlacement, which is  lost in its substance,
without our being able to trace its distribution, or display
the minute structure.   These glands vary in diameter from
the twentieth of an inch to  an  inch.   They  are in gen-
eral red  and  vascular; some, however, are  of a gray or
blackish color.  These  bodies have been denominated  also
lymphatic ganglions,  because some  anatomists  have sup-
posed, that they bear the same relation to their vessels, as
the nervous ganglions do to the nerves.
   The absorbents which enter the glands  are called vasa
inferentia, and those  which pass out of them, are  termed
 vasa  efferentia. 
LYMPHATIC SYSTEM
25
Fig. 7.
Fig. 8.
Fig. 7, a lymphatic vessel.
Fig. 8, a lymphatic vessel laid open, shewing its valves.
Fig. 9, lymphatic vessels and their glands.
LYMPHATIC GLANDS IN PARTICULAR.
LYMPHATIC GLANDS OF THE INFERIOR EXTREMITIES.
  The anterior  tibial gland is the only gland in the leg.
It is found between  the tibia and  fibula, on the lower ex-
tremity of the inter-osseous ligament.
  The popliteal glands  are  three  or  four in number, and
are  situated in the ham.
  The inguinal glands are situated on the upper part of
the  thigh, and in the groin;  the superficial  are found be-
tween  the  skin and  aponeurosis, surrounding  the  termi-
nation of the internal saphena vein ;  their  number varies
from eight to twelve, and  they are  sometimes observed
  VOL. II.              4 
26               LYMPHATIC SYSTEM.

to form a chain of glands, extending from  the middle and
inner part of the thigh to the groin.
  There are three of four  deep seated inguinal glands,
situated  under  the  aponeurosis, and  about  the femoral
artery.


          LYMPHATIC  GLANDS  OF THE PELVIS.

  The hypogastric  glands, ten or fifteen  in  number, are
situated  in the lateral parts of the cavity of the pelvis, and
about the internal iliac vessels.
  On the outside of the pelvis, very small lymphatic glands
are  met with in the  course of the glutaeal and ischiatic
arteries ; and in the interior  of the  pelvis, a number of
minute glands are found upon the bladder, the uterus, and
the vesiculae seminales.
  The  sacral glands  are  situated in  the hollow of the
sacrum,  between the laminae of the meso-rectum.
  The  external iliac glands vary in number from  six to
fifteen, they are situated in the course  of the external iliac
vessels,  and form  a  chain of glands  extending from the
crural arch  to the lower part of the vertebral column.
         LYMPHATIC GLANDS OF  THE  ABDOMEN.

  The lumbar glands are large and numerous;  they occupy
the region of the loins, and surround the aorta and the in-
ferior vena cava; they are also  situated upon the crura of
the diaphragm, and are thickly  arranged  over the  renal
arteries.   These glands  furnish vessels which immediately
communicate with the thoracic duct.
  The hepatic, pancreatic, and splenic glands are situated
round the vena  portae  and along the splenic  artery ;  they 
LYMPHATIC SYSTEM.
27
receive the  lymphatic vessels of the liver, aorta, and pan-
creas.
  The mesenteric glands are numerous, sometimes exceed-
ing a hundred, and  are  in general of considerable size ;
they are  situated between the  two laminae  of the mesen-
tery, and receive the lacteals  or absorbents of the chyle.
See Fig. 11, c, d.
  The mesocolic glands  are fewer than  the preceding, and
are placed between the  laminae  of the mesocolon.
  The gastro-epiploic glands occupy the greater and small-
er curvature of the stomach;  they surround the gastro-
epiploic arteries, and the coronary artery of  the stomach.


          LYMPHATIC GLANDS OF THE THORAX.

  The glands  of the  mediastinum.  Upon the  diaphragm
and pericardium there  are  six  or  eight of these  bodies  ;
and there are  twelve or  sixteen surrounding the thymus
gland, and large vessels of the  base of the heart.
   The  bronchial  glands  are  very  numerous ;  they are
situated  before the division of  the  trachea, around the
bronchi, and even in the interior of the  lungs; but they
will be more particularly noticed in the description of the
trachea and bronchi.


    LYMPHATIC  GLANDS  OF THE SUPERIOR EXTREMITY.

   The glands of the  arm are distributed in  the line of the
brachial artery; they are  not often met with in the fore-
arm, although, not unfrequently, we find a few at the bend
of the arm  near the inner condyle.
   The axillary glands  are situated in the  cellular  tissue
of the  armpit, around  the  axillary vessels   and  their 
28
LYMPHATIC SYSTEM.
branches; they are of  large size, and vary from six to
twelve in number.  Some are met with  under the collar
bone and between the ribs.


      LYMPHATIC  GLANDS  OF THE HEAD  AND NECK.

  The glands of the skull are few in number; several small
glands are found  behind the ear, and two or three are also
observed under the zygomatic arch.   No lymphatic glands
have been traced  in the interior of the skull.
  The glands of  the face are situated upon the buccinator
muscle, and along  the  base of the jaw, where  they sur-
round the anterior portion of the digastric muscle.
  The glands of  the neck  are superficial  and deep seated;
the former are situated beneath  the platysma  myoides, in
the course of the  external jugular vein  and its branches.
The others, called glandula  concatenata, occur in the vici-
nity of the  internal jugular vein and common carotid
artery.  Their size is small, but their number is very great.
In children they frequently present a kind of knotty cord3
extending from behind the ear to the collar bone. 
LYMPHATIC SYSTEM.
29
                      CHAP.  II.

           PARTICULAR LYMPHATIC VESSELS.

LYMPHATIC VESSELS WHICH TERMINATE IN THE THORACIC
                        DUCT.

         1. LYMPHATICS OF THE INFERIOR EXTREMITY.

  The superficial lymphatics of the lower extremities con-
sist  of very  numerous vessels, which are found  in the
cellular tissue, between the skin and muscles.   Their com-
mencement can be traced with  little difficulty in the toes,
round which  they form a very delicate plexus, and form by
their successive  union  from  sixteen to twenty branches,
which cover the surface of the foot and pass up the inner
side of the leg;  those of the side of the foot  collect and
form two or three branches, which  ascend around the
tendo Achilles.
  Thus united, the principal trunks of the  lymphatics of
the leg pass over the calf, and  the ham, and ascend upon
the inner and outer  side of the  thigh, approaching each
other  and continually communicating, until, at  length,
they terminate in the superficial inguinarglands. 
30
LYMPHATIC SYSTEM.
  Fig. 10, the lymphatic
vessels of the inner part
of the thigh.
  All  these  vessels  are
immersed in the subcu-
taneous  cellular  tissue ;
and  their   communica-
tions  are  so   frequent
and numerous, that they
form, upon the  foot, leg
and thigh,  a net-work
which  completely  sur-
rounds these parts.
  The  deep  lymphatic
vessels of the lower ex-
tremities may be distin-
guished into four series :
namely,   the   anterior
tibial, the posterior tibi-
al,  and the fibular lym-
phatics,  according   as
they accompany the  an-
terior and posterior tibial
and   fibular    arteries.
They  terminate  in  the
popliteal  glands.   In-
deed  most of the  deep
seated   lymphatics    of
the  leg and  foot  have
the   same  termination.
These  glands  are  con-
nected  together by a  great  number of smaller vessels,
which form a plexus,  whence issue several  trunks which
ascend  upon  the popliteal and  femoral vessels, receiving
all  the  deep lymphatics of the thigh, and subdividing up
to,  a, the deep inguinal glands.
 
LYMPHATIC SYSTEM.
31
2. SUPERFICIAL LYMPHATIC VESSELS OF THE HIPS, PERINEUM, LOINS,
            EXTERNAL PARTS OF GENERATION, ETC.

  The lymphatics of the hips are numerous, and pass over
the outer and  inner  part of the thigh,  to unite with the
superficial  absorbents  of the  perinaeum, and  inguinal
glands.
  The  lymphatics of the loins descend  from the lumbar
vertebrae  over  the crest of the ilium, and divide  in the
superficial inguinal glands.
  The lymphatics of the lower part of the parieties of the
abdomen  commence on the level  of  the umbilicus,  and
form a net-work  over the whole  anterior region of the
abdomen ;  they collect inferiorly into  a few trunks  which
terminate in the superficial glands.
   The lymphatics of the perinaum, scrotum, and penis, are
very numerous ; those of the scrotum  ascend on  each side
 to the inner part of the thigh, where they unite with those
 of the  perinaeum  and penis :   they all  terminate  in the
 superficial glands.
   In the female, the  lymphatics of the external parts  of
 the  organs of generation have the same termination.


 3. DEEP SEATED OBTURATOR, ISCHIATIC, AND GENITAL  LYMPHATIC
                         VESSELS.

   The obturator lymphatics are distributed over the adduct-
 or muscles  and neighboring parts, and  take  the direction
 of the obturator artery, through the obturator foramen, to
 terminate in the hypogastric glands.
   The ischiatic lymphatics are  distributed to the muscles
 of the pelvis, and terminate in  the  same glands  as the
 former.
   The glutaal lymphatics have  the same distribution as the 
32
LYMPHATIC SYSTEM.
glutaeal artery, and, passing into the pelvis, terminate  in
the same glands as the preceding.
   The deep lymphatics of the penis and clitoris follow the
course of the  interal  pudic artery, and terminate in the
same glands.
  The lymphatics  of the testicle are numerous, and are
among the  largest of the body; some of them are the size
of a crow-quill: they unite upon the spermatic cord into
six or eight branches,  and ascend with  it  towards the in-
guinal  ring, through which they pass to follow  the  sper-
matic artery, and terminate in the lumbar glands.
   The lymphatics of the prostate gland and vesicula semi-
nales unite  with those of the bladder, and enter into the
hypogastric glands.
   The lymphatics of the uterus unite with  those  which are
distributed  to the vagina, to terminate in  the same glands.
Those which are found upon the broad ligament and ova-
rium, ascend with  the spermatic lymphatics to the lumbar
glands.


       4, LYMPHATIC VESSELS OF THE URINARY ORGANS.

  The lymphatics of  the bladder follow the course  of its
blood vessels, and open into the hypogastric  glands.
  The lymphatics of the kidneys unite towards their fissure,
and then proceed upon the sides of the aorta to the lumbar
glands.   The  ureters  also  are  furnished  with numerous
absorbents, which surround those tubes, and communicate
freely with  each other, and with the last named glands.
  The capsular lymphatics proceed  to  the hepatic and
splenic glands, and several pass to the glands  upon the
pillar of the diaphragm. 
LYMPHATIC SYSTEM.
33
5. LYMPHATIC VESSELS OF THE PARIETES OF THE PELVIS AND AB-
                        DOMEN.

  The ileo-lumbar lymphatics are a set of absorbents which
originate in the iliacus  muscle, and upon the hip bone ;
they pass under the psoas muscle, and communicating with
the inferior lumbar glands, contribute  to the formation of
the  external  iliac lymphatic plexus, or the assemblage of
lymphatics which accompany the external iliac vessels.
  The  sacral lymphatics are extended  over  the  adipose
tissue  of  the rectum, and region of the  sacrum ;  they
terminate in  the  inferior  lumbar or  hypogastric glands.
Those lymphatics, which contribute to form the hypogastric
plexus, are placed on the sides of the pelvis, and consist of
an  interlacement of vessels and glands, in which the obtu-
rator,  glutaeal, ischiatic, uterine,  and  vesical lymphatics
terminate.
  The epigastric  lymphatics commence in  the vicinity of
the umbilicus, and proceed from the interior, through the
abdominal muscles  and their aponeuroses;  then unite
into several trunks, which  descend  in the  course of the
epigastric vessels, and terminate in  the external iliac plexus.
  The  circumflex iliac  lymphatics are distributed in the
integuments of the sides of the abdomen, and descend to-
wards the  crest of the  ilium, to  one of the external iliac
glands.
  The  lumbar lymphatics are distributed to the muscles of
the  lumbar region, but they  unite  before the  vertebral
column, where their numerous communications, with those
of almost all the other trunks, which have just been describ-
ed, constitute the lumbar lymphatic plexus.
   vol. ir.             5 
34
LYMPHATIC SYSTEM.
    6. LYMPHATIC VESSELS OF THE STOMACH AND INTESTINES,

  The lymphatics of the stomach are distributed  into  two
distinct orders ; the superficial,  which are situated beneath
the peritoneal, and the deep, which are distributed to  the
muscular and mucous membranes.  Some of these com-
mence at the large extremity of the stomach, and join  the
lymphatics of the spleen ; others proceed from  the small
curvature  of  the  stomach, and communicate  with  the
glands in  that situation, and  in  the vicinity of the liver.
After this, they descend  behind the pancreas to the roots
of the thoracic duct.
  Although  in some animals these vessels have been found
to contain  chyle, in the human  subject they have never
been observed to be filled with  it.
  The lymphatics of the intestines are usually  called  the
lacteals, on account of their  conveying a fluid like milk
from  the intestines  to  the  thoracic  duct.   Each  lacteal
takes its origin from the villi of the  intestines, by numer-
ous short radiated branches, and each branch is furnished
with an orifice for imbibing the chyle.
  From the villi, the lacteals pass under the muscular
membrane of the intestines, and then obliquely through it,
uniting in their course into  larger branches, following the
course of the mesenteric blood vessels.   They are found
situated on  each side of  the arteries.
  It is observed  that there are a much greater  number of
lymphatics in the  small  intestines  than  in the  large ;  the
descending  colon and rectum  present but few  aborbents,
and these are connected with the lumbar  and hypogastric
glands, or those of the mesorectum.
   The lacteals of the small intestines, after passing through
the different glands of the mesentery, form several  trunks, 
LYMPHATIC SYSTEM.                35
which accompany the superior mesenteric artery, until they
arrive at the thoracic duct.

                         Fig. 11.
  Fig. 11, a, a, part of the small intestine; b, b, lacteals;
c, the mesentery ; d, the mesenteric glands.
  The lymphatics of the great omentum ascend  to  unite
with the lymphatics of the stomach, and  terminate  in the
glands of  the great  curvature. 
36
LYMPHATIC SYSTEM.
  7. LYMPHATIC VESSELS OF THE SPLEEN, PANCREAS, AND LIVER.

  The lymphatics of the spleen  are very numerous ;  the
superficial and  deep branches, uniting at  its fissure into  a
few trunks, form a plexus round the splenic vessels, and
pass beneath the duodenal  extremity of the  pancreas, to
the inferior lymphatics of the liver.
  The lymphatics of the pancreas proceed from  the sub-
stance of that gland, and  unite with the lymphatics of the
spleen and stomach.
  The lymphatics of the liver are extremely numerous, nor
does any organ in the  body appear to contain so many;
and, like those  of the other  viscera, it has  a superficial and
a deep seated  series, which, however, so  freely communi-
cate, that, upon injecting the external lymphatics, the deep
internal  are readily filled from  them.  On  the right lobe
they collect into  four fasciculi ; the first is formed by the
lymphatic vessels, which commence between the laminae of
the suspensory ligament, and, uniting into  two or three
trunks, enter  the  thorax   near  the  ensiform  cartilage,
traverse  some of the glands, and open into  the  thoracic
duct  near the  left internal  jugular vein.   The  second
traverses the right lateral ligament of the liver, and divides
into two series;  the  one superior, which mounts into the
thorax, and afterwards returns into the abdomen with the
aorta, to terminate in the neighboring glands ; the other
inferior, which  extends along the last ribs, and unites with
the intercostal  lymphatics, to  open  into the thoracic duct.
The third  fasciculus is  distributed  to  the  middle of the
right lobe,  and  unites with  the preceding at the posterior
part of the liver.   The  fourth fasciculus commences in the
anterior part of the right  lobe, and  unites with  the deep
series, and with some glands near the pylorus.
  In the left lobe of the liver, the  lymphatics unite with 
LYMPHATIC SYSTEM.
37
the preceding and  to  those of the spleen ;  those from the
posterior part of the left lobe descend  towards the cardia,
and  proceed to the glands of the small curvature of the
stomach.
              8. THE THORACIC DUCT.  See Fig. 11.

  The thoracic duct,/, is the canal which receives the lym-
phatics from the lower half of the body, the interior of the
chest,  the  left upper  extremity, and  the left side of the
head and neck.   It extends from  the second or third lum-
bar vertebra as far as the left  subclavian vein, and is form-
ed by the union of, g, five or six large trunks, the result of
the absorbent  plexus of the abdomen.   Near the aortic
aperture of the  diaphragm, the thoracic duct presents a
very remarkable enlargement,  e, the receptaculum chyli,
which is  placed  at the anterior and left part of the second
lumbar vertebra, behind, h, the aorta.   Above  this  dilata-
tion, the thoracic duct ascends into  the chest, entering be-
tween the pillars of the diaphragm,  with  the aorta  on the
left side, and  the  vena azygos  to  the right.   It then
ascends  behind  the arch of  the aorta, and arrives at  the
seventh  cervical vertebra, turns inwards  and downwards,
then passes the thyroid artery, and the left internal jugular
vein, and opens close to the latter into the subclavian  vein
of the same side.   At its aperture there are two valves
which  prevent the blood from  passing from the vein into
the duct.
  Although the lymphatics  have hitherto been  described
by anatomists as collecting  into trunks  to transmit their
contents into  the subclavians  only ;  Magendie*  and a
few  other  celebrated  physiologists and experimentalists

  * Magendie, in his Physiology, relates some very curious and striking
experiments, which, if confirmed by others, must set the question at rest. 
38
LYMPHATIC SYSTEM.
are of opinion, that many other communications, between
the lymphatics and  veins, take place in  the  extremities
and other  parts  of the body.   Professor  Mayo seems
to have arrived at the  same conclusion ;  I give his  own
words.  " For my own part, I think  it likely, that  such
communications do  exist.   At all events, when believing
that they did  not, I have witnessed  the mercury thrown
into the absorbents of the  limbs  unaccountably make its
way into the veins."*


ft LYMPHATIC VESSELS WHICH THE THORACIC DUCT DIRECTLY RE-
                        CEIVES.

   Several branches of lymphatics from  the  liver, and the
glands surrounding  the caeliac artery, have  been already
described.
   The intercostal lymphatics are  distributed to the  mus-
cles of the thorax  and the intercostals;  they communi-
cate with some glands found  between  the external and
internal intercostal planes of the  muscles.   On the  sides
of the vertebrae, these vessels unite with  others which pro-
ceed from the spinal canal  and the  muscles of the back,
then spread  out into  a plexus before the vertebral col-
umn.  From  thence  they  descend  and  open into the
thoracic duct,


           10. LYMPHATIC VESSELS OF THE LUNGS.

  The lymphatics of the lungs  are distributed upon  their
surface in a series of areolae of various forms, more  com-
monly hexagonal, and unite into a number  of trunks which

  •Outlines of Human Physiology, by Herbert Mayo, Professor of Anat.
King's College, London. 
LYMPHATIC SYSTEM.
39
enter the glands, with which the  bronchus is  surrounded
at its entrance  into that  organ.   The  deep lymphatics
occupy  the  whole tissue of the lungs, communicate with
the superficial, unite into the bronchial glands, and ascend
upon the trachea.
  From a  large bronchial gland, which is  found in the
angle formed by the  division of the  trachea,  there  issue
several  lymphatic  branches, which ascend upon the tra-
chea, and, traversing some glands,  unite and open into the
right great lymphatic vessel.   Others traverse glands upon
the trachea, under the thyroid gland, and collect into two
trunks, which incline obliquely to the left, behind the inter-
nal jugular  vein, to discharge themselves into the thoracic
duct.


11. SUBSTERNAL, DIAPHRAGMATIC,  CARDIAC, THYMIC, AND ^CESOPHA-
                 GEAL LYMPHATIC VESSELS.

   The  substernal  lymphatics  commence from  the  upper
part of the  parietes of the abdomen ; they enter the tho-
rax  between the  ensiform cartilage  and the diaphragm,
ascend behind the sternum, traverse some glands, and form
some meshes, which unite  into trunks, one of which com-
municates with the inferior jugular glands, and terminates
in the thoracic duct.  The  others  open on the right side
into the subclavian and internal jugular veins.
   The lymphatics  of the diaphragm are  distributed on  its
convex surface, and unite with the intercostal and hepatic
lymphatics,  then  proceed through the  inferior glands of
the  mediastinum, and  join the  preceding behind  the
sternum.
   The  lymphatics of  the  pericardium  and thymus  are a
numerous  set of reticulated  vessels, which  are  intimately
connected  with the  substernal and pulmonary lympha-
tics. 
40
LYMPHATIC SYSTEM.
   The lymphatics of the heart are distributed to the whole
 surface ;  the principal  trunks following the course of the
 coronary vessels.   Some of these trunks ascend upon  the
 anterior part of the aorta, and  terminate in the thoracic
 duct; others pass  obliquely between  the aorta and  pul-
 monary  artery, traverse some small glands, and arrive at
 the thoracic duct.
   The lymphatics of the oesophagus are  reticulated around
 that tube; they unite with  those of the heart and  lungs,
 and terminate in  the predorsal ganglia.


     12, LYMPHATIC VESSELS OF THE SUPERIOR EXTREMITIES.

   The superficial lymphatics of the upper extremities  col-
 lect into fasciculi on the sides of the fingers, and proceed
 over the metacarpus to the posterior  surface of the fore-
 arm, where their numbers  are  greatly  increased by  the
 addition  of small vessels from that part of the  extremity.
 Near the elbow joint the lymphatics are very distinct; and,
 upon the  anterior surface of the fore-arm, they  unite with
others, which  arrive from  the  fingers and palm of the
hand.  They then ascend on the fore and inner  part of the
arm, and, becoming large and numerous, terminate in the
axillary and subclavian glands.
  Some of the brachial lymphatics pursue the course of the
cephalic vein, and unite with some reticulated vessels  and
glands under the clavicle.
  The deep lymphatics of the upper extremities constantly
accompany the  arteries which are distributed to these parts,
and terminate in the axillary glands. 
LYMPHATIC SYSTEM.
41
13. LYMPHATIC VESSELS OF THE ANTERIOR PARIETES OF THE THO-
                        RAX.

  The lymphatics of the  anterior part of the thorax com-
mence immediately under the integuments, and, proceed-
ing upwards and outwards, terminate in  the glands of the
axilla.
   Some  of these  vessels  originate more  deeply  in the
substance of the pectoralis major, pectoralis minor, and ser-
ratus magnus  muscles, but they have  the  same termina-
tion.


14. LYMPHATIC VESSELS OF THE POSTERIOR REGION OF THE  NECK
                      AND THORAX.

   The lymphatics of the neck  commence  in  the  cellular
tissue, towards the occiput, and upon the spinous processes
of the neck ;  they descend  outwardly  in the direction of
the  fibres of the  trapezius, and  unite  with the  anterior
thoracic, and dorsal lymphatics in the axilla.
   The lymphatics of the  back commence  in the integu-
ments, and  are  extended  to the  whole of the  muscles
of  the back ; like the preceding,  they  terminate  in the
axilla.


           15. LYMPHATIC VESSELS OF THE AXILLA.

   The axillary  lymphatics are remarkably reticulated,  in
consequence of their connection with  a great number of
glands, and with the vessels which  terminate in them, or
issue from them.   The latter concentrate into three or four
trunks, which  proceed  round the  subclavian vein, and open
into it, and into the thoracic duct.  Those on the  right
   VOL. II.              6 
42
LYMPHATIC SYSTEM.
side generally furnish a trunk, which transmits its fluid to
the angle  formed by the right internal jugular and sub-
clavian veins ; and is named the right great lymphatic duct.
See Fig. 5,/.


16. LYMPHATIC VESSELS OF THE HEAD AND ANTERIOR PART OF THE
                         NECK.

   The epicranial lymphatics are  arranged on all sides  be-
neath the skin of the  cranium, and may be distinguished
into three orders of fasciculi.  The occipital, the temporal,
and the frontal; all which proceed to the glands of the
neck.
   The  lymphatics of the face  follow  the direction  of
the principal veins,  and  proceed  to  the  submaxillary
glands.
   The  superficial lymphatics  of  the neck form a  plexus,
which  accompanies  the  subcutaneous veins of the neck ;
they open into the right great lymphatic vessel, and the
thoracic duct.


     17.  DEEP LYMPHATIC VESSELS OF THE HEAD  AND  NECK.

   The  lymphatics  of the  brain.   Although  the most
minute  researches have  been made in  those parts, there
have been discovered a few lymphatics only in the dura
mater.
   The  deep lymphatics of the tongue, palate, nose,  orbits,
pharynx, muscles of the face, etc.  These absorbents ac-
company the blood vessels, and  terminate in the right and
left great thoracic ducts. 
LYMPHATIC SYSTEM.
43
THE  OFFICE OF  LYMPHATIC VESSELS AND THEIR  GLANDS.

  The most important office of the lymphatic system is to
collect the chyle for the supply of the waste of the body,
during the exercise of its several functions.
  The lymphatics, therefore, take  in  the fluids, it is sup-
posed, by capillary attraction, and  afterwards,  by a con-
tractile power, inherent in the vessels, conduct  their con-
tents  into the mass  of the blood.  The absorbents  also
have  the  power of removing the solid  parts of the body,
and by thus making way for the disposition of new matter,
contribute to  the  growth and renovation of the animal
fabric.
  By means of these vessels, on the one hand,  many con-
tagious  diseases are communicated ;  and,  on  the other
hand, diseases are removed : thus, when lymph is formed,
or pus collected, or blood effused in the tissue of organs,
the lymphatics have  the power of taking away the extra-
neous or diseased  matter.  And even  solid  tumours often
are known to disappear entirely by the action of this sys-
tem of vessels.  The obvious use of the absorbent vessels
is to  convey the lymph and  the chyle into the venous sys-
tem ;  the former, the residue of nutrition, and the latter,
the product of digestion.
   I cannot dismiss this  subject without informing the un-
initiated student, that there is much difficulty in exhibiting
the lymphatics.  They must be injected with quicksilver,
and,  owing to the minuteness and delicacy  of the vessels,
it requires the most acute sight of the anatomist to distin-
guish, and  to  introduce an instrument into the smaller
branches.  Caution and  patience, however,  will surmount
this difficulty ; and nothing will more repay  the trouble, or
reflect more credit on the skill of a practical  anatomist,
than  a good preparation of the lacteals, or other lymphatics. 
ART.   VII.
                      CHAP. I.


                   NERVOUS  SYSTEM.

  The nervous system is destined to regulate the functions
of the animal economy, and to receive impressions of ex-
ternal objects,  and transmit them to the understanding.
  The nervous system consists of, 1st, the brain ; 2d, the
medulla oblongata; 3d, the spinal marrow; 4th, the nerves;
5th, the ganglia.


      GENERAL DIVISIONS OF  THE NERVOUS SYSTEM.

  There are two general  departments, essentially distinct
from  each  other,  to which the nervous system  may be
referred ; the 1st department consists of the  brain and its
dependencies,  the 2d,  of  the ganglia and their  nervous
radiations.  The first  department  appertains  particularly
to animal life  ; on the one  hand it is the agent which
transmits impressions  calculated  to produce  sensations ;
on the  other  hand it  serves to  convey the  volitions to
those  organs which receive them.  The second department
is almost invariably distributed to the organs of digestion, 
NERVOUS SYSTEM.
45
of circulation, respiration, and the secretions, and belongs
in a more particular manner to the internal organs, where
it acts a more obscure part than the preceding.   The two
departments frequently communicate with each other, but
there is a sufficiently distinctive  line to establish  their dif-
ference ;  as  a simple exposition  of each will sufficiently
demonstrate.
    1. THE CEREBRAL DEPARTMENT OF THE NERVOUS SYSTEM.

  This department of the nervous system, like all organs
of animal life, is exactly symmetrical.  The nerves com-
mence alike from each side of the brain and spinal cord :
hence  the  appellation of  pair of nerves, by which the
double corresponding trunk is described.  This is a term
which we cannot apply to  the irregularly distributed gan-
glionic department.
  Each department of  the  nervous  system receives im-
pressions of objects, and  transmits them to the sensorium;
and these impressions or affections of the nerves, accom-
panied by  consciousness,  bear the name  of sensation.
The nerves, which  constitute the immediate  instruments
of sensation, are of different kinds, and are distributed in
different  proportions  in  the various  organs of the body:
most of them are capable of being excited  by agents both
from without and from  within, and the  impressions they
receive are transmitted to the brain, their common centre,
and frequently to the other  organs with which  they are
connected.   That the nerves  are truly the organs of sen-
sation  cannot be  disputed ; for sensation is found  to be
most acute in those parts which are furnished with most
nerves, and the sensation ceases when the nerves are de-
stroyed.   When the nerve is stimulated, the muscle which 
46
NERVOUS SYSTEM.
it supplies is  convulsed ; when it is tied, compressed, or
divided, palsy of the muscle ensues.
   My present arrangement  of the  departments of  the
nervous system,  is chiefly founded  on  the  anatomy and
distribution of the nerves.  And here  science  must ac-
knowledge its obligation to  Sir Charles Bell, for  his
important  discoveries,  relative  to  the functions of  the
nerves.   So that, by the  operation  of new views, many
formerly received opinions must be reformed, or altogether
expunged.  As  I proceed, therefore, in the work, I shall
endeavor  to demonstrate, from anatomical and physiologi-
cal facts,  that every part  of the system has its peculiar
endowment of nervous  matter,  fitting it for the peculiar
function it has to perform.  For example, it is necessary
to distinguish  nerves into sensitive, motive, compound and
organic, and in addition to the  limited number of senses,
usually  reckoned  in the  human  subject, there are other in-
ward organs of sensation, which will subsequently be de-
scribed, which have distinct functions, and depend  on as
distinct departments of  the nervous system, as either see-
ing, hearing, or touch.
   I  shall  now claim  the attention of the reader  to  the
general  distribution of the nervous system.
   The  brain  appears to be  the most remarkable part of
the nervous system, since all intellectual  phenomena must
be referred to the cerebral mass.   This organ furnishes
generally  the  motive for  all our actions  upon  exterior
bodies, exerts  a greater or less influence upon all the pro-
perties of life,  establishes an  active  relation  amongst  the
different organs, and is the  principal agent of sympathies.
It is, moreover, in a sensible relation with the objects with
which we  are surrounded.
   There are  two orders of the cerebral department of
nerves ; the 1st constitutes the nerves of sensation ;  the
2d, the  nerves of motion. 
NERVOUS SYSTEM.
47
  The nerves of  sensation of the  first  order, which are
immediately connected with the brain, are endowed with
particular properties, which adapt them to the impression
of special bodies ;  namely, the first pair of nerves perceives
odours, the second light, the eighth sound ; and the lin-
gual branch of the inferior  maxillary nerve distinguishes
the taste and  flavor of bodies.  The  special  senses, how-
ever, I shall hereafter more particularly refer to.
  The medullary column, or spinal  marrow, appears next
in importance to the brain.  It is an irregularly cylindrical
prolongation of the brain ; it is not  like the Grecian shaft,
a simple column, but like the Gothic, a compound column,
having several shafts combined.  In other words, the spinal
marrow is composed of four parts  or cords, two on each
side, which are united  the whole length.   From the ante-
rior cord, of each  side of the column, issue the nerves of
motion ; from the  posterior  cords, the nerves of sensation.
There is another  column,  which is  only continued the
length of the medulla oblongata, from which the respirato-
ry nerves take their origin.
   The spinal  nerves  are  perfectly  regular in their deriva-
tion and distribution.   There are thirty, or thirtytwo, on
each side; this variation in the statement of  the number
depends on the method of reckoning.   Each nerve com-
mences by two distinct roots ; Fig. 12, the one, c, proceeding 
48
NERVOUS SYSTEM.
Fig. 12.
from the anterior ; the other, b, from the posterior division
of, a, the medullary column ; and  each of these  roots is
composed  of  a number of small filaments, which, imme-
diately after their origin, approach  each other ; the poste-
rior filaments  form, d, a ganglion, and then join  the  an-
terior to form, e,  a spinal nerve:  each nervous  filament
must be considered as  continuing  distinct to its  ultimate
destination, though, by the union of the anterior and pos-
terior,  the  several spinal nerves possess the double pro-
perty of  conveying  sensation, and   producing  motion.
There  are  other  nerves of the fifth, sixth, and ninth,
which  are  distributed  separately, and are solely motive
nerves, but the fifth  nerve of the  encephalon is  like  the
spinal nerves,  in having a double derivation, and a two-
fold  function  of sense  and  motion.   Sir Charles  Bell
performed  numerous  experiments  to prove  the  correct-
ness of  his theory,  and these  experiments  have been
repeated on  the  Continent by Magendie  and others,
who have  been perfectly satisfied with  the accuracy of 
NERVOUS SYSTEM.                49
his conclusions.*  It must, therefore, now  be considered
as an established fact, acknowledged by all anatomists, that
the  nerves,  proceeding from  the  anterior cord  of the
spinal marrow,  bestow the  power  of muscular motion ;
and  that those which proceed from the  posterior  part of
the medullary column, produce sensation.  When, for in-
stance, the  roots  of the anterior  nerves of the leg are
divided, the animal  loses all the  power of  moving the
leg,  although the limb retains its  sensibility; but, if the
roots of the  posterior nerves are cut, the  power of  motion
continues,  though  sensibility is destroyed.   The  experi-
ments have  been repeated and varied, yet with similar re-
sults.   Thus, on the posterior part of the spinal cord being
irritated with a pointed  instrument, the animal immediately
manifested signs of pain ; but no apparent effect was pro-
duced by irritating the anterior part.   Every muscle, then,
has  two distinct orders of nerves ;  the one a motive, and
the other a sensitive ; and nerves of each of these orders
are distributed to every muscular fibre.
  It requires, therefore, for the full operation of  muscular
power, two different orders of filaments, and  these  estab-
lish  a circle between the sensorium and the  muscle ;  so
that the nerves of the one order carry the influence of the
will towards the muscles, which nerves have  no  power of
transmitting an impression  back again to the brain.  The
nerves of the other order connect  the  muscles  with the
brain, by acting as a  sensitive agent in conveying  the im-
pression of the  condition of the muscle  to the  common
sensorium;  but the last mentioned  nerves have no opera-
tion in a direction  from the  brain to the muscle,  and, in
consequence, do not excite the muscle however irritated.
  We find, however, that the brain  and medulla spinalis,

  *For details, I refer to the papers of Sir Charles Bell, in the Philo.
Transac. of the Royal Society.
   VOL. n.               7 
50
NERVOUS SYSTEM.
as also the nerves communicating with them, are endowed
with different properties ; the common design of which is
to give us  correct intelligence of the relative condition of
our existence.  The assemblage of these different parts
has, consequently, with propriety,  been  called  the ner-
vous  department  of  external life, or of animal life.
When the functions of this part of the nervous system are
suspended, as by a fit of apoplexy, the  individual is  de-
prived of feeling, and is perfectly insensible to every sur-
rounding object.
   It has already been observed, that these nerves are en-
dowed with  two properties, viz. :  sensibility, and vis-mo-
trix;  hence, it  follows,  that there must  be  nerves  of
sensation and motion.   And physiological  experiments,
and  the  observations drawn from  pathological  anatomy,
evidently prove,  that sensation resides in the nervous fila-
ments, connected with the posterior column of the medulla
spinalis ;  and motion in those which are extended from the
anterior column.
   As general corollaries, the  nerves of sensation receive
the impressions  which external agents produce  upon us,
and transmit them  to the brain.  If a ligature be applied
around a nerve, or if the nerve be cut transversely, we find
that sensation is  totally destroyed in that part  to which
the nerve is distributed, because the  brain is not  in direct
communication  with  it.  " The brain,  therefore,  is  the
only organ that enables us to appreciate the objects which
surround us ; the senses being its  advanced guards, and
the nerves its media of communication."
   1. The senses receive impressions.
   2. The nerves convey impressions to the brain.
   3. The brain  perceives and judges, according as  they
appear useful, agreeable, or  hurtful.
   In conclusion  it appears, that, without the due  functions
of the brain, we should neither possess external sensation, 
NERVOUS SYSTEM.
51
nor be  competent  to  execute any voluntary movement;
consequently,  it has been said, with much truth, that the
nervous  system is, in fact, all the  animal;* the other sys-
tems being vegetative and  automatic, and existing only to
nourish  and defend it.   Besides the properties of sensation
and volition, which are common  to other animals, man is
distinguished from them by that faculty which he possesses
from the Creator, of being able, by means of his nervous
system,  to compare, associate, and judge of the impressions
which he does or has received, and to deduce from them
the greatest consequences.
  Possessing a faculty which constitutes the most beauti-
ful  and most  noble attribute of our  species,  nature  also
ordained that its functions should correspond with the de-
gree of  perfection and  extension of the cerebral mass.   A
deficiency in the general conformation of the brain, the
slight developement of some  of its parts, and  the evident
or obscure  alteration  occurring  in  its structure, are so
many causes capable of deranging the whole or part of the
intellectual faculties of man.f  Anatomists and physiolo-
gists have failed in the attempt  to trace the precise  differ-
ences between the  organization of the  idiot  and another
man ; though there is no doubt that the defect exists in the
organization of the brain, since an idiot possesses a soul in
common with another man.


  CEREBRAL DEPARTMENT OF THE NERVOUS SYSTEM.

                the brain in general.

  The brain is that mass which fills the cavity of the skull.
It is  distinguished  by  its  divisions  into  the  cerebrum,
* Baron Cuvier.
t Manec. 
52
NERVOUS SYSTEM.
the cerebellum, the pons varolii, and the medulla oblon-
gata, all of which, in the adult, weigh about three pounds;
occasionally the brain is  found to exceed  this weight by
several ounces, according to the size of the head.   In the
dimensions of the brain there is a great difference in dif-
ferent individuals.   The volume  is generally in proportion
to the mental capacity.   Let us not suppose, however,
that every person having a large  head is necessarily a per-
son of  superior intelligence, for there  are many causes
of an augmentation of the head besides  the  size of the
brain.
   The color of the  brain varies in different  individuals and
at different ages ;  the color probably depending on the
quantity of blood sent  to it: hence, it has a redder hue  in
early than in advanced life, and becomes still more deeply
colored in consequence of inflammation.
   The  weight of the brain of a  full grown man is about
three pounds ; that of  a woman is somewhat less.
   Baron Wenzel paid great attention to this department
of anatomy, and  has published a very interesting table, of
which the subjoined is  an extract. 
NERVOUS SYSTEM.
53
	Weight	Weight	Weight	Proportion
Age.	of whole	of brain	of cere- 1	of brain to
	brain.	only.	bellum.	cerebellum.
	Grains.	Grains.	Grains.	
Male embryo of 5 months	720	683	37	18H -1
Female embryo of 8 months	4960	4610	350	13 A :1
Girl at birth ....	6150	5700	450	12§ 1
Girl at 3 years old . . .	15240	13380	1860	7TeT :1
Boy 3 years ....	13050	11490	1560	7Tfft:l
Man 18 years ....	20940	18474	2466	75o2 . 1
Man 31 years ....	24120	21480	2700	8A :1
Man 54 years ....	20580	18060	2320	m :1
Man 63 years ....	22500	19780	2720	737 .1 'TTF • *
Man 72 years ....	22620	20200	2420	8 *2.• 1 °TJT • y
Man 80 years ....	19080	16500	2580	6-5-V- 1
 
54
NERVOUS
  Fig. 13.  The left side
of the brain  and spinal
marrow, shown by mak-
ing a  section  of the cra-
nium  and the  spinal co-
lumn, and  removing the
dura mater.
  a, the  convolutions of
the cerebrum.
  b, the laminae  of the
cerebellum.
  e, the pons varolii.
  g, the medulla oblon-
gata,
  c,  d, f, the  medulla
spinalis, extending  from
the first cervical to the
first lumbar vertebra, and
terminating in the cauda
equina.
   The  cerebrum is the
largest  portion  of  the
brain, and occupies the
whole  upper  cavity  of
the skull.  It rests ante-
riorly, upon the arches of
the orbits ; in the centre,
upon the middle  fossae of
the base of  the skull;
and posteriorly, upon the
tentorium  cerebelli. 
NERVOUS SYSTEM.
55
           THE  EXTERIOR  OF THE CEREBRUM.

  The upper surface of the  cerebrum is divided into two
parts, termed hemispheres, which are separated by the falx
cerebri.
  The surface of the cerebrum in  general, both above and
below, is intersected  by deep fissures and  eminences,
which  produce numerous turnings and windings, termed
convolutions; these take a  variety of directions, and differ
in extent in different parts of the brain.
  The convolutions are smallest at the anterior part of the
brain, larger  posteriorly, and  are  largest at the  superior
and central part of the hemispheres, where  each  convolu-
tion is about half an inch in breadth.
  The number  and size of the convolutions vary exceed-
ingly in different individuals ;  and, indeed, they are seldom
found the same in the two hemispheres.  They extend in-
to the substance of the brain about an inch, and are lined
by prolongations of the pia mater.
  The lower surface of the brain is formed into three dis-
tinct regions, which are named lobes.  The anterior lobes
are separated by  the termination of  the  grand  division
which  separates the hemispheres.  On each of these lobes
we observe a deep  rectilinear groove, directed  from behind
forwards, for lodging the trunk of the olfactory nerve.
  The anterior and  middle  lobes are  separated by  the
fissura sylvii.
  Between these interlobular  fissures, is the union or com-
missure of the  optic nerves.   Behind  this  commissure is
the cineritious tubercle, which forms  the floor  of the third
ventricle, and contains in its centre a small white nucleus.
  From  the  middle of this tubercle, a  sort of slender co-
nical prolongation,  of a reddish color, descends obliquely 
56
NERVOUS SYSTEM.
forwards, named the pituitary stem*  It passes under the
commissure of the optic nerve, and terminates in a small
body,  situated  in  the  pituitary  fossa  of  the   sphenoid
bone.
   The pituitary body\ is the small organ just alluded to.
It has not the vascular  structure peculiar to glands, but is
composed of two portions :  the first is of a grayish  yellow
color;  the second is soft, and impregnated with a whitish
viscid fluid.   The pituitary  body, in the adult, generally
contains small calculus  concretions.
   The corpora albicantia, or mam malaria, are  situated be-
hind the  cineritious  tubercle;  they consist of two small
bodies of the  form  and size of  peas, which are  white ex-
ternally, and of a gray color internally ;  they are united to
each other by a small  grayish band, which contributes to
form the floor of the third ventricle.
          THE  EXTERIOR OF THE CEREBELLUM.

  The cerebellum  is situated in the inferior fossae of the
occipital bone,  under the posterior lobes of the cerebrum,
and is separated from those lobes  by the tentorium.   It is
about a sixth  part of the  size of the  cerebrum, and has
been  compared to two depressed  spheroids, placed beside
each other on a horizontal plane.  These are divided pos-
teriorly  by the falx minor.   The surface of the cerebellum
presents an  assemblage of gray  laminae, over which the
arachnoid  membrane passes.  Each lobe  commonly  has
from  sixty to sixtyfive  of  these  laminae.  But, on  sepa-
rating these  principal laminae, we  perceive many  other
smaller, concealed in the grooves, and partly covering each
other.
* Formerly denominated the infundibulum.
t Formerly denominated the pituitary gland. 
NERVOUS SYSTEM.
57
  The upper surface of the cerebellum presents, on its fore
and middle part, an elongated eminence, termed the supe-
rior vermiform process, which is formed by the reciprocal
crossing  of the laminae, of  which the two lobes of this
organ are composed.  The whole of the  upper surface is
occupied  by five  fasciculated  lobules, common  to both
lobes, and disposed in transverse arched bands.
  The lower surface of the cerebellum presents a deep de-
pression in the middle line, named, the valley, in which is
lodged the commencement of the spinal marrow ; posteri-
orly, it is  divided into two, by a large eminence, called the
inferior vermiform process.  Anteriorly, it is terminated by
a narrow  rounded prolongation,  named  the mammillary
eminence of the inferior vermiform process.
  The inferior part of the cerebellum  presents a convex
surface, on which we may distinguish four lobules, which
describe  concentric arches.  At the outer side of the first
lobule is  a  small  foliated  tuft, distinguished by the small-
ness of its laminae, named, the lobule of the par vagum.


          THE EXTERIOR OF  THE PONS  VAROLII.*

   The pons varolii forms as it were the centre of the brain,
and of which it weighs only the sixtieth part.  It is placed
between  the cerebrum and  cerebellum, and is formed by
processes from them, termed their crura.
   The anterior surface of the pons varolii is named, by
Gall, the commissure of the cerebellum.  Along the medi-
an line we observe a depression occasioned by the situation
of the basilar artery.
   The posterior surface of the pons  varolii presents, on
its  upper part, four tubercles, which are white exiernally,

               * Tuber annulare, or nodus cerebri.
   VOL. II.             8 
58
NERVOUS SYSTEM.
and gray internally ; these are termed the tubercula quadra-
gemina.  The two upper are named  the nates, the two
lower the testes.   The pineal body corresponds to the point
of intersection of the two grooves which separate the tu-
bercles.  Behind  the tubercula  quadragemina is a pulpy
lamina, of a grayish color, which ascends towards the cere-
bellum, called the valvula vieussenii.  Behind the  point
where it leaves  the  pons  varolii, we  may observe an
aperture, which is the posterior orifice of the aqueduct of
sylvius,  by which the third and  fourth ventricles commu-
nicate across the substance of the  pons varolii.  Farther
down, is a slightly excavated surface, which forms the ante-
rior  part of the fourth  ventricle.   It  is separated in its
whole length by a narrow angular groove, which commences
at the aqueduct of sylvius, and terminates in the spinal
marrow opposite the atlas.   This groove is called the cala-
mus scriptorius, from its supposed resemblance to a pen.


               THE MEDULLA OBLONGATA.

   The medulla  oblongata is that  portion of the cerebral
formation,  which extends from  the pons varolii, to the
great foramen of the occipital bone.
   Upon  the surface of the  medulla  oblongata there are
two  small  eminences, which run longitudinally, and con-
tiguous to  each other, and from  their form  have obtained
the  name  of  the  corpora pyramidalia.  Between  these
eminences there  is a deep fissure, into which the blood-
vessels of the pia mater penetrate, to supply the interior of
the medulla.
   On the outside of the former  eminences are two others,
which, having somewhat  the figure  of olives, they are
termed the corpora olivaria. 
NERVOUS SYSTEM.
59
Fig. 14.
  Fig. 14, the base of the brain.
  a, the anterior lobes.      b, the middle lobes.
  k, the posterior lobes.     n, the pituitary stem.
  c, the corpora albicantia, or mammallaria.
  d, the pons varolii.
  h, h,  the medulla oblongata.  The letters are placed on
the corpora pyramidalia.
  /, the cerebellum.
  i, i, the corpora olivaria.
  e, the superior vermiform process
  g, the inferior vermiform process.
  The posterior surface of the medulla oblongata is directly
continuous with the pons varolii, and contributes to form
the fourth ventricle.   On each side of the upper and back 
60
NERVOUS SYSTEM.
part of the  medulla oblongata, we observe  two  whitish
oblong eminences, named  the corpora restiformia, which
contribute to the formation of the cerebellum.


                THE MEDULLA SPINALIS.

  The medulla spinalis or spinal marrow is a long, irregu-
larly cylindrical  cord, which  extends within the vertebral
canal, from the great occipital foramen, to the second lum-
bar vertebra.  Its  weight is  about  one-twentieth part of
that of the brain.
  The anterior surface of the medullary cord corresponds
to the bodies of the vertebrae.  A very deep and distinct
fissure is extended  its whole  length, dividing it into two
equal lateral portions.   Its posterior surface is also divided
by a  similar median line, which commences between the
two  corpora restiformia.   By  this disposition, the spinal
marrow is divided into a double cord, intimately connected
in its total extent.
  On  the  posterior and anterior surfaces of the body of
the spinal cord,  on each side, and at  some distance from
the median groove, are collateral depressed lines, in which
we find the roots of the spinal nerves.
  Finally, it presents  a great number of  small transverse
grooves particularly  apparent from the last cervical to the
ninth dorsal vertebra.
  The exterior  of  the spinal cord consists of a  layer of
white substance, half a line thick, and after immersion in
alcohol, this peels  readily into longitudinal  fibres, which
are separable  into filaments that continually branch, and
thus attach themselves to those adjoining.
   Upon  making a  transverse  section  of the spinal cord,
a thin curved layer  of gray matter is  seen  in  each lateral 
NERVOUS SYSTEM.
61
half, the convex margin of which is inwards, and is joined
to its fellow by a transverse layer.
      THE INTERNAL ORGANIZATION OF  THE BRAIN.

  The brain  is soft  and pulpy, but its  density varies ac-
cording to the age.   In infancy it is extremely tender and
yielding, and it acquires firmness as  the person advances
in life.  Its specific  gravity, in the adult, is 1310.  The
cerebral tissue is soluble in water, insoluble in alcohol and
fixed  oils.
          CHEMICAL  ANALYSIS  OF THE  BRAIN.

  According to M. Vauquelin there is no difference of
composition in the different parts of the nervous  system :
the analysis  of the brain, of the cerebellum, of the  spinal
marrow, and the nerves gives the  same  result.  He found
in them  all the  same matter,  the composition of which
is of
            Water,......80-00
            White fatty matter, .   .  .   4-53
            Red fatty matter,   .  .  .    0-70
            Osmazome,   .   .  .   •  •   1*12
            Albumen,.....7-00
            Phosphorus,.....1'50
            Sulphur and  salts, such as
            Phosphate of potass,  .   }
               "      of lime,   .   .  >  5-15
               "      of magnesia,   )

   The substance of the brain presents two distinct modi-
 fications. 
62
NERVOUS SYSTEM.
  1st.  The cortical or cineritious substance covering  the
brain in general, about  the  sixth of an inch in thickness ;
it also enters deep between its  convolutions, and  is dis-
tributed through different parts of its interior.  This part
of the brain, when  examined with a microscope, appears
to consist of minute molecules, smaller than the red parti-
cles  of the  blood.  They  are connected  together by a
transparent tissue, containing a serous  fluid, and  supplied
with very minute and infinitely numerous blood-vessels.
  2d.  The  medullary  or white  substance   is firmer and
denser than the former ; its mass is also much  greater than
that of the  corticular substance, and is filled  with a great
quantity of vascular ramifications, which, on making a sec-
tion of the  brain, present  so  many red points  with  the
blood oozing from them.
  All the fasciculi of medullary fibres placed in the medulla
oblongata, appear to expand so as  to form the mass of the
brain ; and  more especially  to originate from the pyramidal
and olivary eminences.  The  fibres of the former  on  the
one side proceed to the opposite side, crossing each other,
and progressively acquiring  more volume as they ascend to
form the cerebral mass.
  These two substances of the brain do not constitute one
homogeneous mass, but are arranged into a great variety
of eminences, cavities,  laminae, partitions, etc. differing in
their color, consistence, and volume.  I shall now proceed
to demonstrate the brain in each of these particulars, not
by  attempting  to unfold the structure in  the manner of
Reil and Spurzheim, but  shall describe the  several parts
as they are  exhibited in the recent and most familiar modes
of  dissection.*
   The corpus collosum or  commissura  magna is the centre

  * In order to exhibit the fibrous  and lamelated structure of  the brain, it
 must be immersed for a requisite time in alcohol. 
NERVOUS SYSTEM.
63
of communication between the hemispheres:  it  is seen,
without making an  incision,  by merely separating these
hemispheres  with  the  fingers.  It consists of a large por-
tion of medullary  matter, which by transverse  fibres, in-
corporates and unites the two  lateral divisions of the cere-
brum.
  The centrum ovale is the appearance which  is exhibited
when the brain is cut horizontally, on the level of  the cor-
pus callosum; the corpus  callosum  constitutes the centre
of the great medullary mass of the cerebrum, and  the cor-
tical substance, being on its edges, forms the central white
mass into an irregular oval.
  In the middle of the  corpus callosum there is a  longitu-
dinal  line called the raphe; it has a medullary cord on
each side, from which numerous short transverse lines pro-
ceed, termed the transverse medullary traces. 
64
NERVOUS SYSTEM.
Fig. 15.
   Fig. 15, a transverse section of the brain, upon a level
with the corpus callosum.
  a, a,  a. the corticular part of the  convolutions, with
the fissures between them.
  b, b, the medullary part, forming  the  centrum  ovale of
Vieussens.
  c, the raphe, on each side of which are longitudinal ele-
vated lines, and transverse striae.
  In the  substance  of the  brain  we  find  four  cavities
termed the ventricles.
  There are  two lateral ventricles,  one is  situated in the
central part of each hemisphere.   They are of an irregular
form, lying  under the centrum ovale,  and  each having
three winding prolongations termed cornua.   The anterior
cornua are separated  from each other by a partition, called 
NERVOUS SYSTEM.
65
the septum lucidum; the posterior cornua are at a consid-
erable distance from each other, but as they curve inwardly
and dip into the  middle lobes of the brain, they approach
nearer at their po nted extremities.  The cavities of these
ventricles are principally situated between the  corpus cal-
losum and the corpora striata, and thalami nervorum opti-
corum.
  Fig.  16, a horizontal  section of the cerebrum, a  little
deeper than in Fig. 15.
  a, a, the anterior cornua of the lateral ventricles.
  b, b, the posterior cornua.
  c, c, the corpora striata.
  e, e, the optic thalami.
  f d, the septum lucidum, showing the fissure termed the
fifth ventricle and extending between the two letters,—
  g, g, the choroid plexus.
  VOL. II.              9 
66
NERVOUS SYSTEM.
  The lateral ventricles communicate with each other, and
with the third ventricle by an opening,  named the foramen
monroianum, under the arch of the fornix.
  The septum lucidum, or septum of the ventricles, is a soft
and thin  medullary production, which is continuous above
with the middle part of the  inferior surface of the corpus
callosum ; inferiorly, it is  connected with  the fornix, and
forms a distinct partition between the lateral ventricles.  It
is composed of two laminae with a narrow  cavity between
them, which has been considered by Cuvier as b. fifth ven-
tricle.


     parts observed  in  the  lateral ventricles.

  The fornix is a flat triangular medullary  body, having its
upper surface contiguous to the corpus callosum, and sup-
porting the septum lucidum.  Its lower surface is situated
upon the choriod plexus and optic thalami; one of the an-
gles is forward and the other two are towards the back part;
and the foramen of Monro is under the most anterior part.
  The posterior angles of the fornix have a bifurcated pro-
longation ; one of the branches of which is short, and loses
itself in  the white layer  of the cornua  ammonis.  The
other, which is long, is named the corpus fimbriatum; it is
flattened, and extends into  the lowest part of the lateral
ventricle.
  The corpora fimbriata, or  tania hippocampi, are the
plaiting  of  the margin of the  processes of the  fornix,
which pass into the inferior cornua of the ventricles.
  The pes hippocampi, or  cornu ammonis, is found at the
termination of the line called taenia  hippocampi, at the
posterior prolongation of the fornix.
  The psalierium, or lyra, consists of numerous transverse
lines, which are impressed upon the under surface of the
posterior part of the body of the fornix. 
NERVOUS SYSTEM.
67
  The choroid plexus is displayed  by dividing the body of
the fornix  and inverting it.  This  plexus consists  of  a
spongy mass of tortuous vessels and reddish granulations,
covering the optic thalami  and corpora striata, and contin-
ued into the inferior cornua of the lateral ventricles.  The
plexus of each side is  connected to its fellow by the velum
interpositum, a vascular membrane which passes under the
fornix, and lies on the third ventricle and corpora quadrige-
mina.    The  plexus returns  its  blood  by two  parallel
branches, termed the venae galeni ; these veins run back-
wards, and enter the sinus rectus.
  The corpora striata are two  smooth cineritious pyriform
eminences, broad before and  contracted behind ;  they are
situated  in the  fore part  of the lateral ventricle.  Their
color at the outside is gray, somewhat tinged with brown;
but on cutting them obliquely, cineritious and  medullary
substances are seen  disposed in their interior, in alternate
streaks.   The white fibres may be traced to the original
fasciculi  of the corpora olivaria.
  The optic  thalami are  two oval  medullary eminences,
placed by the side of each other, between  the  diverging
extremities of the corpora striata;  their upper surface forms
a part of the floor of the  ventricles;  their  lower surface
presents, externally, two prominences.   The corpora geni-
culata, which furnish several  filaments to the optic nerve,
may be seen at the  inferior surface of the cerebrum.
   The commissura mollis is a band of a gray color, connect-
ing the convex surfaces of the optic  thalami.
   The tania semicircularis is a line of white semitranspa-
rent substance, running between the convex surface of the
 optic thalami and the corpora striata. 
68                NERVOUS SYSTEM.

                           Fig. 17.
  Fig. 17.  a, a, the optic thalami, on the outer margin of
which is seen  the taenia semicircularis.
  e, e, the corpora striata.
  d, the cavity (termed the fifth ventricle) which exists be-
tween the two laminae of the septum lucidum.
  c, the anterior pillars of the fornix cut off at their base.
  b, the fornix turned back, shewing on its inferior surface—
  /, the lyra.
  g, the taenia semicircularis or white line separating the
surface  of the corpora striata and the thalami.
  The  commissura anterior  cerebri is a  short  cylindrical
medullary cord, extending  transversely between  the  cor-
pora striata, immediately under the anterior  prolongations
of  the fornix.
  The  vulva is a small aperture formed by the anterior pro-
longations of the  fornix, bifurcating and adhering on each 
NERVOUS SYSTEM.
69
side, between the corpus striatum, and the thalamus  nervi
optici.  This aperture is the part by which the three ven-
tricles communicate.
  The third ventricle is situated between the optic thalami
and the crura cerebri;  it is a deep fissure.   At the upper
and fore part it communicates with the  lateral ventricles,
and, at the lower part, with the infundibulum.  The latter
opening is called  iter ad infundibulum.   A  canal  extends
backwards under the  tubercula  quadrigemina,  into  the
fourth ventricle.   This passage  is called  the aqueduct of
SYLVIUS.
  The anus, or foramen commune posterius, is situated be-
hind  the commissure of the optic thalami, and is the ante-
rior aperture of the  aqueduct of sylvius.
  The commissura posterior is a transverse cord at  the pos-
terior part of the third  ventricle.
  The  pineal gland is situated beneath  and behind the
fornix, and above the tubercula quadrigemina ;  it is a small
grayish  body of  the size of a pea; it is perfectly isolated
from the cerebral  substance, excepting at the fore part,
where it is connected  to  the optic thalami  by two medul-
lary cords, — the peduncles of the pineal  gland.  In  the
adult it contains little calculi, very hard  and resembling
grains of coarse sand.


     the internal  structure of the cerebellum.

   The substance of the cerebellum is composed of cineri-
tious and medullary matter, as in the  cerebrum.  The cin-
eritious, however, bears a  much  greater proportion in the
former than in the latter.
   The arbor vita is a beautiful tree-like appearance, which
we observe on making  a vertical  section of the cerebellum.
This appearance is formed by the peculiar arrangement of
 medullary and cineritious matter. 
70
NERVOUS SYSTEM.
   The corpora restiformia are processes of medullary mat-
ter,  which  extend from  the medulla oblongata  to the
medullary crura of the cerebellum.
   The fourth  ventricle is the ventricle of the cerebellum;
the sides of this cavity are formed by it, the anterior part
by the medulla oblongata, and the upper and back part by
the valvula vieussenii.
  The calamus scriptorius is the groove and its pointed ter-
mination in the  fourth vetricle, which vesalius  conceived
to have a great resemblance to a writing pen.
  The aqueduct of sylvius enters the upper part of this
ventricle, and  the valvula vieussenii hangs over it.
  Fig. 18, a  horizontal section  of the cerebrum and  an
oblique division of the cerebellum.
  a, the anterior part of the corpus callosum. 
NERVOUS SYSTEM.
71
  b, the corpus striatum.
  c, the optic thalamus.
  d, the taenia semicircularis.
  e, the anterior  pillars of the fornix cut off at their base.
  /, the commissure of the optic thalami.
  g, the pineal gland, situated on the four eminences, term-
ed the corpora quadrigemina.
  h, valvula vieussenii.
  k, the arbor vitae shewn by an oblique section of, n, the
cerebellum.
  I, the fourth ventricle, terminating in,—
  m, the calamus scriptorius.
  n, the ce.rebellum.
  The  arteries of  the  cerebrum  and  cerebellum  are
branches of the internal carotid and vertebral arteries, from
the latter  of  which arises the  basilar artery ; ramifications
of these vessels communicate  with  each other, and form,
what is termed, the arterial circle of Willis.
  The spinal marrow  receives its arteries from the verte-
bral, dorsal, lumbar, and sacral arteries.
  The veins of the brain  are  very delicate in their struc-
ture ;  they communicate  with  the sinuses  of the dura
mater, and the sinuses pour their contents into the internal
jugular veins.
  The veins of the spinal marrow  terminate in the verte-
bral, dorsal, lumbar, and sacral veins.
  No lymphatic  vessels have  yet  been discovered in the
brain. 
72
NERVOUS SYSTEM.
Fig. 19.
  Fig. 19, exhibits the brain placed  on its  base,  with a
vertical incision made through the corpus  callosum, as far
as the anterior commissure, and continued posteriorly to
the tubercula quadrigemina.   The  hemispheres are sepa-
rated from each other and turned to each side.  The  sep-
tum lucidum  and fornix  are removed.  The  cerebellum,
in a similar manner, is  divided as far  as the  fourth ven-
tricle.
  a, a, the cut edges of the corpus callosum.
  b, b, b, b, the tubercula  quadrigemina.
  c, the pineal  gland.
  d, medullary striae in  the fourth  ventricle, which form
the beginnings of the auditory nerves.
  e, the third ventricle. 
NERVOUS SYSTEM.
73
  /, part of the pituitary stem,
  g, the medullary portion of the cerebellum.
  h, the fourth ventricle.
  i, the calamus  scriptorius, at the inferior part of  the
fourth ventricle.
  k, the medulla  spinalis.
  I, the taenia semicircularis.
  m, the peduncle of the pineal gland.
  n, a section of  the anterior commissure of the brain.
  The brain is the primary organ of sensation ; the mind
is supposed to be  most immediately and intimately connect-
ed  with  it, and,  from observations and  experiments, it is
found to communicate  nervous influence to all the other
parts  of the body.   That the  brain is the organ  of  the
mind, is evident  by the connection between the brain and
the organs of sense, by our  consciousness,  and by  the
mental  disturbance  which  ensues under disease of  the
brain.   In asserting, however,  that the brain  is the organ
or instrument of  the mind, it is not intended to convey an
idea that the mind is material, but that the exercise of the
 mental powers depend on the living brain.
vol. n.
10 
74                NERVOUS SYSTEM.
                      CHAP. II.

      THE MEMBRANOUS ENVELOPES OF THE BRAIN.

   The membranes of the brain  are called matres by the
 ancients, from  a notion  that  they gave origin to all  the
 other membranes of the body : no argument is required to
 refute so absurd an opinion.
   The membranous envelopes of the brain consist of the
 dura mater, the tunica arachnoidea, and  the pia mater.

                   I. THE DURA MATER.

   The dura mater is the outermost envelope of the brain ;
 it is common to that organ and to the skull, that is, it in-
 closes  the brain and its appendages, and  performs the  office
 of an internal periosteum to the cranium.
   This membrane is of a very firm and  compact  texture;
 it is composed of tendinous-like fibres, which have a glossy,
 semitransparent, and pearly appearance.  It is divisible by
 maceration into two or more fibrous layers.
   The outer surface of  the  dura mater  adheres  rather
 loosely to  the  bones of the skull, and  is easily detached
from  them; but  at the sutures and foramina it  is  more
 firmly  connected than elsewhere.
   The inner surface of the dura mater is remarkably smooth,
and forms several folds, which are named the falx cerebri,
the tentorium cerebelli, and the falx cerebelli.
   The falx cerebri is a duplicature or process of  the dura
mater, and has some resemblance in  shape to the blade of
a sickle, from which circumstance it has obtained the name
of falx.  It separates the two  hemispheres of the  brain
from each other.   Its upper edge, which is  extended from
the frontal ridge to the middle groove of  the occipital bone, 
NERVOUS  SYSTEM.
75
lodges the superior longitudinal  sinus.  Its lower  edge
passes over the corpus callosum, and  contains the inferior
longitudinal sinus.   Its  anterior extremity is attached to
the crista galli;  the posterior  is continued  into the tento-
rium, and contains the straight sinus.
  The tentorium cerebelli is a membranous partition which
separates the cerebrum from the cerebellum.  Like the falx
cerebri, it is in a continual state of tension.   Its outer cir-
cumference contains the lateral sinus, and is connected to
the edges of the lateral groove of the  occipital bone.   The
inner edge  corresponds  to  the cerebral  protuberances.
The extremities of the tentorium meet at an acute angle,
and cross over each other, like the letter X, to be attached
to the clinoid processes of the sphenoid bone.
  The falx cerebelli is a  process of the dura mater, which
is placed between the lobes of the cerebellum, and is ex-
tended from  the internal occipital protuberance, to the
great occipital foramen.
  The dura mater is evidently fibrous,  and its fibres are very
apparent in the folds just mentioned,  and, in particular, at
the upper part of the falx cerebri.   Some minute nervous
filaments have been discovered in the  course of the arteries
of the dura mater.  The blood vessels are not very numer-
ous.  The principal branches of the arteries are distributed
upon the external surface ; minute ramifications only being
observed on  its inner surface.  The smaller veins of this
membrane accompany the arteries, the larger veins consti-
tute the sinuses which I am about to describe.
             SINUSES OF THE DURA MATER.

  The sinuses of the dura mater are merely the large veins
of the brain, which are received into  triangular canals of
the dura mater; they vary in their dimensions, and are dis- 
76
NERVOUS SYSTEM.
posed in a regular symmetrical manner.  They are formed
externally  by the dura mater, and  internally by a smooth
membrane, similar  to  that which is met with in the veins.
As they are  constantly stretched in all point of their ex-
tent, they can neither  change their situation nor contract
upon themselves.  They are remarkable for having at in-
tervals fibrous bridles,  which  pass irregularly from side to
side  of the canal.   All the veins of the dura mater and of
the  brain pour their blood into the sinuses.
   Fig. 20, a,  a transverse  section of the
superior longitudinal sinus.
   6, a similar section  of the  inferior  longi-
tudinal sinus.
   c, a portion of the cranium.
   The superior longitudinal sinus is a long
triangular  canal, which, commencing  at the  crista galla of
the ethmoid bone, and extending along the  upper edge of
the falx cerebri, becomes  gradually larger  in its progress,
and  terminates in the  lateral sinuses.
   The inferior longitudinal sinus is much smaller than the
preceding, and is situated at the inferior margin of the falx,
extending  from its anterior third to the tentorium cerebelli,
terminating posteriorly by two branches in the straight sinus.
   The torcular herophili* is an irregular cavity situated
at the union of the three great  folds of the dura mater ;  it
presents six apertures, viz.:  1st, that of the superior longi-
tudinal sinus ;  2d,  two inferior, corresponding to the occi-
pital sinuses; 3d, one anterior  belonging to the  straight
sinus ; 4th, two lateral openings on the right and left lead-
ing into the lateral  sinuses.
   The straight sinus is situated at the base of the falx;  it
is a  continuation of the vena  galeni, and  extends from

  * The term torcular was  originally applied, from a  supposition that the
blood is squeezed in this sinus as in a wine press.
 
NERVOUS SYSTEM.                 77
the termination of the  inferior  longitudinal sinus  to the
torcular herophili.
  The occipital sinuses are situated on the sides of the oc-
cipital foramen, and passing into the falx  cerebelli,  open
into the torcular herophili.
  The lateral  sinuses are very large, and extend  from the
torcular  herophili to the commencement of the jugular
veins, occupying the lateral grooves of the  occipital bone,
as far as  the foramen lacerum posterius.
   The coronary sinus surrounds the pituitary fossa; it is
very small in its whole course, and opens to the  right and
left into  the cavernous sinuses.
   The cavernous  sinuses  are very broad and short; they
are situated in  the lateral  grooves of the sphenoid bone.
They commence beneath the anterior clinoid processes, and
terminate in the inferior petrous sinuses.  The outer pari-
etes  of  this sinus contain, in their substance, the common
motor, the pathetic, and ophthalmic nerves.  The cavity
of the cavernous sinus is occupied by a number  of reticu-
lated filaments  ; the internal carotid artery, and the external
motor nerve of the eye.
   Beneath the pituitary body the two  cavernous  sinuses
communicate by the sinus transversalis sella turcica.
   The superior petrous sinuses extend from the termination
of the preceding sinuses, towards the summit of the petrous
portion of the  temporal  bone,  and open into the lateral
sinuses.
   The inferior petrous sinuses  extend from the cavernous
sinuses,  to the inferior edge of the petrous  and basilary
processes, and terminate in the lateral sinuses.
   The anterior occipital sinus forms a communication be-
tween the two petrous sinuses and the cavernous sinus, by
extending transversely, at the upper part  of the basillary
 process. 
78
NERVOUS SYSTEM.
Fig. 21.
  Fig. 21.  A lateral view of the veins of the processes of
the dura mater, termed the sinuses.
  a, the falx.
  b, the tentorium cerebelli.
  c, the superior longitudinal sinus.
  d, the straight sinus.
  e, the lateral sinus.
  /, the internal jugular vein.
  g, the inferior longitudinal sinus.
  h, the occipital sinus.
  i, the vena galeni.
  k, the torcular herophili.


               2. THE ARACHNOID MEMBRANE.

  The arachnoid membrane is situated between the dura
mater and pia mater ; it has  been named  arachnoid, from 
NERVOUS SYSTEM.
79
 its extreme thinness, resembling a spider's web; it is ex-
 tended over the convolutions of the  cerebrum, the  cere-
 bellum, and the base of the pons varolii.
   The exterior arachnoid membrane does not adhere to the
 other  membranes of the brain, for it  can be  very easily
 raised by insufflation with a blow pipe; it possesses no ap-
 parent vascularity, but is constantly moistened with a serous
 fluid, and forms a sheath or envelope for all the nerves and
 all the vessels which  enter or issue from the skull.  This
 membrane also passes downwards into the vertebral canal,
 around the spinal marrow, and furnishes a conical sheath
 for each of the vertebral nerves.
   The interior arachnoid membrane is continuous with the
 preceding ; penetrating into the third ventricle by a small
 oval opening, found between  the corpus callosum  and
 tubercula quadrigemina, and lining the third ventricle, and
 extending over the choroid plexus, it is continued over the
 parietes  of the lateral  and fourth ventricles, into which it
 passes through the aqueduct of sylvius.


                    3.  THE PIA MATER.

   The pia mater is the third membrane of the brain ; it is
 a cellular, loose, transparent web, in which  a  multitude of
 blood vessels, more or  less  delicate, cross  each other in  a
 thousand different directions, and it is  attached  to the sur-
 face  of the brain by the minute branches of these vessels,
which penetrate into the latter organ.   It invests the brain
on all  sides, dipping into the convolutions of the  hemis-
pheres, and covering the superior surface  of the  corpus
callosum ; covering inferiorly the base of the brain and the
pons varolii : it is also reflected over the cerebellum, and
sinks between its concentric laminae. 
80
NERVOUS SYSTEM.
  The pia mater  penetrates  into the  third  and  lateral
ventricles  by the great fissure, which is  situated between
the corpus callosum  and the pons varolii, and  by the
two  lateral fissures.   It forms, 1st, the choroid  web, a
triangular membranous  prolongation, lining the  poste-
rior part of the corpus callosum, and the inferior  surface
of the  fornix, to  which  it  adheres by numerous small
vessels.   2d, the  choroid plexus,  an  elongated  fold of
the pia mater, having an  appearance of vascular cords,
attached to the choroid web, and  extending into the  lat-
eral  ventricles, along  the  sides of the fornix ; this plexus
communicates  with that  part of the external  pia mater
which descends between  the thalami of the optic nerves
and  the fimbriated bodies.   We perceive in the choroid
plexus a  number  of small granulations  which many ana-
tomists have  considered as glands ;  but  Chaussier asserts
that they  are membranous fringes, which may be unfolded
by agitating  them in water.   We  also occasionally find
among the vessels  of  this  plexus small vesicles  filled  with
serum.
   GRANULATIONS OF  THE MEMBRANES OF  THE BRAIN.

  On the various parts of the  dura and pia mater, there
are small whitish bodies, of the intimate texture and office
of which we are entirely ignorant.
  The superior longitudinal  sinus contains  a great number
of these granulations ; they are designated  by the name of
the glands of Pacchioni.
  Sometimes a  few  of them  are  found  in the  torcular
herophili, and  at  the orifices of the venae  galeni.  All
the other sinuses are destitute of them.
  Graniform  bodies,  similar  to those met  with  in  the
sinuses^ are also found in the  pia  mater, especially about 
NERVOUS SYSTEM.
81
the outside of the superior longitudinal  sinus, and around
the cerebral veins.
  The internal pia mater  contains some of these granu-
lations ;  they are also  observed in  the  choroid plexus,
the velum interpositum, and in the web of the fourth ven-
tricle.
    the proper membrane of the spinal marrow.

  The character of this membrane is  sufficiently marked
to distinguish it from the  pia  mater.   It is not, therefore,
a continuation of the latter, but  a strong and somewhat
fibrous tissue, of a yellowish  color, corresponding, by its
external surface, to the arachnoid, without uniting with it;
laterally it is continuous with the neurilemma of the verte-
bral nerves, and ligamentum denticulatum.   By its internal
surface it is adherent to the spinal marrow.


              ligamentum  denticulatum.

  The ligamentum  denticulatum is  a whitish, transparent,
thin,  but strong  band, extending, on  each  side, between
the anterior  and posterior  roots of the  vertebral  nerves,
from the occipital foramen, to the termination of the spinal
marrow.  In the interval of each  cervical and dorsal pair
of nerves, its  external border presents twenty or twenty-
two denticulated portions, the points of which are fixed to
the dura mater.   Its internal border adheres to the proper
membrane of the spinal marrow.   Its use appears to be to
keep the spinal marrow steady in  its canal.
  vol. n.              11 
82                NERVOUS SYSTEM.


               THE NERVES IN GENERAL.

  The nerves are either cylindrical or flattened white cords,
which are extended from the brain, or from the spinal mar-
row, to every part of the system.
  All the nerves are arranged symmetrically and in pairs,
and are composed of a greater or less number of filaments,
connected together by cellular tissue.   The filaments which
terminate the  branches of the  nerves unite with other
nervous  filaments, or elude our  observation in the tissue
of the organs which they supply.  Fig. 22, a portion of a
nerve invested with its neurilemma, and consisting of dis-
tinct filaments, one of which is drawn out.
  If two or more nervous branches are connected together
by numerous filaments sent to each  other, so that  there
results a  sort of net-work, the name of plexus is given to
this distribution.   Fig. 23, is an instance drawn from the
axillary plexus.
                         Fig. 23.
 
NERVOUS SYSTEM.                83
  Most of the nerves are  composed of a greater  or less
number of cords, formed of filaments of the same nature.
On separating these cords and fibres, we perceive that they
send frequent branches to each other, so as to form a kind
of plexus in the very substance of the nerve.
  The neurilemma is the external membrane which  forms a
canal for the  white medullary  matter  of the nerve : this
may be readily shewn by immersing a nerve in an alkaline
solution, by which the medullary matter is removed ; and
the nerve appears like a fasciculus of tubes.  The olfactory
nerve  has  no neurilemma, and it is only found round the
optic nerve after its commissure.
   The nerves are amply supplied with blood vessels, which
are distributed on their surface, and penetrated into their
substance, and between their component fasciculi.
   In some of the  principal nerves absorbent vessels may
be traced, and reasoning from analogy, we may conclude
that there are no nerves destitute of them.


       NERVES OF THE CEREBRAL DEPARTMENT.

   By the older anatomists, the cerebral nerves were divi-
ded into nine pairs; the facial  and auditory nerves being
termed the seventh pair, and the eighth consisting of  the
glosso-pharyngaeal, par vagum  and the  spinal accessory.
The division at present adopted, is into twelve pairs.


           OLFACTORY NERVES, OR  FIRST PAIR.

   The olfactory nerves  are very soft in their texture, and
 after death are  soon  decomposed ; they should, therefore,
 be demonstrated in a recent  subject.   They are connected
 to the brain  by three filaments ; the  1st, is  external and 
84
NERVOUS SYSTEM.
medullary, and is in union with  the  corpus striatum ;  the
2d, internal and  medullary, is united to the white  sub-
stance which  occupies the internal  part of the fissure of
sylvius ;  the 3d is  cortical, and is situated at the point of
junction of the two preceding, uniting to them  by its
summit.   At the point of their union, the olfactory nerve
presents a triangular enlargement.   Fig. 24, a, extending

                         Fig. 24.
horizontally forwards and  inwards,  and  dividing into a
greater or less number of branches which traverse the fora-
mina of the cribriform  plate of the  ethmoid bone, to be
distributed at d, on the turbinated bones of the nasal fossa,
the septum narium, and the roof of the nasal fossa.
  This  nerve transmits to the brain the impression which
odours produce upon the pituitary membrane.


            OPTIC NERVES, OR SECOND PAIR.

  The optic nerve, with the exception of the trifacial nerve,
is  the largest  nerve that  issues from  the  cranium.   It
is connected to the  optic thalami and the tubercula  qua-
drigemina by two bands, which are extended  from  these
eminences to the optic thalami.  The two nerves  unite 
NERVOUS SYSTEM.
85
in front of the pituitary fossa, and are so confounded with
each other, as to render it impossible  to affirm, in a posi-
tive manner, whether they cross each other, as many ana-
tomists  have supposed,  or  whether  their  substance is
mingled and identified at  their union;  the latter opinion is
most  probable.
   The optic nerves afterwards separate ;  each nerve being
perfectly cylindrical,  isolated and enveloped in a  neuri-
lemma ; it then passes through the optic foramen, and sur-
rounded by the  recti muscles in the  orbit, arrives at the
posterior and inner part of the globe of the eye; entering
the sclerotic and choroid membranes, it terminates in the
retina.
                THIRD  PAIR OF NERVES.

  The third pair,  or motores  oculorum, Fig.  25, a,  are
smaller than, c, the optic nerve ; each nerve is attached to
the back part of the crura cerebri, by filaments which are
soon collected  into their several trunks.   These pass on
the upper  part of the cavernous sinus, on the outside of
the foramen lacerum, into  the  orbit, and  divide  into  the
following branches :  1st, the superior branch, e, e, which is 
86
NERVOUS SYSTEM.
distributed to the superior rectus and levator  palpebrae ;
2d, the inferior branch, f, which supplies the other recti
muscles \ 3d, a filament to the lenticular ganglion, and in-
ferior oblique muscle.


               FOURTH  PAIR OF  NERVES.

  The fourth pair of nerves or nervi pathetici, b, are the
most slender of the body.   Each nerve is attached by three
or four filaments, beneath the tubercula quadrigemina, and
the lateral part of  the  valve of Vieussens.    This nerve
turns round the crus cerebri, perforates the dura mater at
the edge of the tentorium, passes the cavernous  sinus on
the outer side of the third nerve, and proceeds through the
foramen lacerum, to supply the superior oblique muscle of
the eye.


           FIFTH PAIR, OF TRIFACIAL NERVES.

   The  trifacial nerves are the largest of the  brain ; they
are attached, first, between the corpora  olivaria and resti-
formia by a fasciculus of white fibres, which ascend above
the posterior  part of the pons varolii, at  the outer edge
of which they leave the brain ; each forms a large flat cord,
composed of two distinct fasciculi;  the one anterior, con-
sisting of five or six filaments ; the other, which is posteri-
or, forms a  grayish enlargement, termed  the  Gasserian
ganglion, from the anterior part of which proceed three
branches;  viz. the  ophthalmic, the superior maxillary, and
the inferior maxillary. 
NERVOUS SYSTEM.
87
1. THE OPHTHALMIC, OR FIRST BRANCH OF THE  FIFTH  PAIR OF
                        NERVES.

  The ophthalmic  nerve  passes  the  external part  of the
cavernous  sinus, receiving a filament  from  the superior
cervical ganglion, and, passing through the  foramen lace-
rum orbitale, divides into  the lachrymal, the frontal, and
the nasal nerves.
  The lachrymal nerve proceeds along the external part of
the orbit,  gives  off the  spheno-maxillary  branch,  which
unites with a branch of the superior  maxillary nerve ; and
the molar branch, which unites with a branch of the facial
nerve ; it furnishes  also several  branches to the lachrymal
gland, and to the superior  eyelid.
  The frontal nerve is found in the upper part of the orbit,
where it divides into two filaments.   The internal frontal,
which is distributed to the  frontal  sinus, the corrugator
supercilii, and frontalis muscles, and the subcutaneous cel-
lular tissue of the forehead.
  The external frontal filament, passes through the supra
orbitary  foramen, and  is distributed  to the frontalis mus-
cles, and to the integuments extending over the summit of
the head.
  The nasal nerve passes under the superior oblique mus-
cle ; it  frequently  receives a filament from  the  superior
cervical  ganglion, and furnishes a very delicate filament to
the lenticular ganglion, and also, two or three ciliary fila-
ments : it at  length divides into two branches ;  the internal
nasal,  which re-enters the cranium  by  the anterior  in-
ternal orbitary  foramen, and  from  thence again  passes
down through  one  of  the perforations of the cribriform
plate of  the ethmoid bone, to be distributed to the septum
narium and  the nasal  fossae.  The external branch passes
out of the orbit, beneath the pulley of the superior oblique 
88
NERVOUS SYSTEM.
muscle, and is distributed  to  the  lachrymal passages and
dorsum of the nose.


2. THE  SUPERIOR MAXILLARY  NERVE, OR SECOND BRANCH OF THE
                       FIFTH  PAIR.

  The superior maxillary nerve is extended from the gang-
lion of the fifth pair;  it enters through  the foramen ro-
tundum of the sphenoid bone into the  spheno-maxillary
fossa, where it receives filaments from the spheno-palatine
ganglion ; it  then  passes  through  the infra-orbitar  canal
and terminates  on the  cheek.   It furnishes, 1 st, the or-
bital branch which passes into the orbit by the spheno-
maxillary fissure,  and  there  divides into  the  malar and
temporal filaments.   2d. The  posterior and superior den-
tal branches  which enter the  passages  in the maxillary
tuberosity, and dividing into many filaments are distri-
buted  to the roots of the three  last  molar  teeth, and to
the gums.  3d. The  anterior  dental branch  which de-
scends  into  the anterior  dental canal,  and  divides into
filaments, which are distributed to the incisor, the canine,
and the  two small molar teeth.  4th. The infra-orbitar
branches which  form the termination of the superior max-
illary nerve ;  these pass out  by the infra-orbitar  foramen,
and uniting with filaments from the facial, nasal and buccal
branches, are distributed to the  muscles and integuments
of the cheek.


3. THE INFERIOR MAXILLARY NERVE, OR THIRD BRANCH OF THE
                        FIFTH PAIR.

    The inferior maxillary nerve passes through  the fora-
 men ovale of the  sphenoid bone, and is distributed  to
 the lower jaw, and   the muscles situated  between  it 
NERVOUS SYSTEM.
89
and the  os  hyoides; it  furnishes the following branches
viz. —
   1st.   Two deep temporal nerves which are distributed to
the inner part of the temporal muscle.
   2d.  The masseteric nerves which are distributed to  the
articulation of the jaw and the masseter muscle.
   3d.  The buccal nerve which passes between the ptery-
goid muscles, and divides into six or seven filaments which
are distributed  to the temporal, buccinator,  and levator
anguli oris muscles, to the angle of the  mouth, and finally
to the integuments.
   4th.  The pterygoid nerves, two very delicate filaments
which are directed downwards, and terminate  in the inter-
nal pterygoid  muscles.
   5th. The lingual or gustatory nerve, of considerable size,
and which receives the filament called  the corda tympani,
which extends  from  the spheno-palatine ganglion.  The
lingual nerve afterwards  descends between the pterygoidei
muscles, and furnishes in its passage a filament to the in-
ternal pterygoid muscle ; several  to the tonsils and to  the
superior  constrictor of the pharynx;  two  or three to  the
back  part of the gums,  and  to  the  submaxillary  gland ;
several filaments are  distributed  to the sublingual gland,
and to the mucous  membrane  of the mouth :  lastly, it
divides into numerous filaments which penetrate the mus-
cular tissue of the tongue, and ascending towards the supe-
rior surface terminate in the  numerous  papillae ; in conse-
quence of which, this branch is considered as  the principal
nerve  of the organ of taste.
   6th.  The inferior dental nerve, which enters the dental
canal, and is divided into branches which are distributed
to the teeth and to  the cancelli of the bone : some  fila-
ments, named the mental nerves, pass  out of the  anterior
maxillary foramen, and are distributed to the lower lip  and
chin.
   VOL. II.              12 
90
NERVOUS SYSTEM.
  The auricular or superficial temporal nerve,  proceeds
backwards and outwards  between  the condyle of the jaw
and  the  auditory canal; it  communicates with the facial
nerve, giving  off branches to the  temporo-maxillary arti-
culation, and to the pavilion  and integuments of the ear;
it is ultimately distributed to  the integuments of the tem-
ples and  forehead.

                         Fig. 26.
  Fig. 26, exhibits the trifacial nerve and the distribution
of its three principal branches.
  a, the trunk of the trifacial  nerve.
  q, the Gasserian ganglion.
  b, the frontal.
  /, the lachrymal.
  g, the nasal nerves of the ophthalmic branch. 
NERVOUS SYSTEM.
  r, the superior maxillary branch.
  /, the malar.
  i, the anterior dental.
  h, the posterior dental.
  k, the infra orbitar nerves.
  c, the inferior maxillary branch
  s, the two deep temporal.
  t, the masseteric.
  n, o, the lingual.
  e, the inferior dental.
  p, the sublingual nerves.


                SIXTH PAIR OF NERVES.

  The sixth  pair of nerves are very small;  they are at-
tached to  the sides  of  the corpora  pyramidalia, each pro-
ceeds to the line which separates  the  pons varolii from
the medulla oblongata; here the filaments unite and pro-
ceed along the  basilar  groove through the cavernous sinus,
pass through the foramen  lacerum orbitale,  and are  distri-
buted to the external rectus muscle of the eye.
  While in the cavernous sinus, the sixth nerve is placed
between the ophthalmic nerve and  the carotid artery, upon
the surface of the  latter of  which, two  or three filaments
are extended to the great  sympathetic nerve.


     SEVENTH  PAIR OF NERVES,  OR FACIAL NERVES.

  The facial nerve is the  portio  dura of  the  old anato-
mists ; it appears beneath the posterior and external part
of the pons varolii, from  the line between the  corpora
olivaria and  restiformia;  it enters  the internal  auditory
foramen with the acoustic nerve, then  leaves the  latter to 
92
NERVOUS SYSTEM.
proceed into the aqueduct of fallopius, passing out of
the cranium  by the  stylo-mastoid foramen.  On a  level
with  the  hiatus fallopii, it  receives a filament of the
Vidian nerve, which enters the cavity of the tympanum,
under the name of corda tympani.   The  facial  nerve also
furnishes filaments to the muscles of the tympanum, the
pavilion, and the  integuments of the ear.  On its exit
from  the  stylo-mastoid  foramen,  it  gives  off  the  pos-
terior  auricular,  the  stylo-hyoid,  and  the sub-mastoid
branches.
  The facial  nerve  then enters the parotid gland, and is
distributed to the muscles and the integuments of the  face.
These branches separate and reunite at different places, so
as to form a plexus on the side of the face, which has  been
called the pes anserinus. 
NERVOUS SYSTEM.
93
Fig. 27.
   Fig. 27, exhibits the superficial  nerves of the face and
neck:  the parotid gland is removed to shew the divisions
of the facial nerve which pass through it.
   a, the divisions of the facial nerve, termed the pes anse-
rinus.                                                  ■
   b, the supra orbitary nerve.
   c, the infra orbitary nerve.
   d, the mental nerves.
   e, the first cervical nerve.
  f, descending branches  communicating with the hypo-
glossal and cervical nerves. 
94
NERVOUS SYSTEM.
          EIGHTH PAIR, OR  AUDITORY  NERVES.

  The auditory nerve is the portio mollis of the old anato-
mists.   It is  attached over  the  restiform body, from the
substance of  a  small gray band, which unites it to the
floor of the  fourth ventricle.  We  may observe also  a
small band which seems to unite this part of the auditory
nerve, and furnishes it with a  commissure.   This nerve ac-
companies the facial, so long  as it is contained  in the skull
and  internal  auditory canal; but at the bottom of this'
canal it divides into branches, which are distributed to the
cochlea, the vestibule and the semicircular canals.  In the
description of the organ of hearing, these will  be particu-
larly noticed.  This nerve transmits  to the brain the im-
pressions which sound produces upon the internal ear.


                NINTH PAIR  OF  NERVES.

  The  glosso-pharyngeal,  or ninth pair of nerves,  is at-
tached in the line which separates the corpora olivaria from
the corpora restiformia ;  each nerve  has three or four fila-
ments which  unite  into a single cord, which  is directed
through the  foramen  lacerum, and is separated from the
pneumo-gastric nerve by the  internal  jugular vein.   After
its exit  from the  cranium, it sends a filament to the audi-
tory canal, receives a filament from the  facial, and another
from the pneumo-gastric nerve ; ♦several  filaments are dis-
tributed to the carotid artery, and others communicate with
the cervical ganglia.   It gives branches  also to the muscles
of the pharynx, to the mucous glands, to the fauces, and at
length  terminates in the tongue.
  It gives motion to the muscles of the tongue and pha-
rynx, but more especially to those necessary for the articu-
lation of the voice. 
NERVOUS SYSTEM.                95
                TENTH PAIR OF  NERVES.

  The pneumo-gastric nerves,  or par vagum, sometimes
called the eighth pair, are connected to the brain, immedi-
ately beneath  the  preceding, behind the  corpora olivaria,
near the corpora restiformia.  Each commences by numer-
ous filaments,  which unite and form two or three fasciculi,
placed under each other;  but, on  passing out of the  cra-
nium through  the  foramen lacerum posterius, they form a
round cord, which  descends with the great sympathetic, on
the lateral part of  the neck, on the outer side of the primi-
tive carotid, and posterior to the jugular vein; it passes
into the chest  behind the subclavian vein, and accompanies
the oesophagus to the stomach.   It presents a multitude of
variations in its secondary divisions, so  that we seldom find
it alike in two subjects ; but it constantly furnishes —
  1st.   The pharyngeal nerve, which  is  distributed to the
pharynx, and  forms the pharyngeal plexus.
  2d.  The superior laryngeal  nerve, which is  distributed
to the muscles of  the larynx, the  thyroid gland, and  the
mucous membrane of the larynx and pharynx.
  3d.   The cardiac nerves.  On the right side the pneu-
mo-gastric nerve supplies two or three filaments, descending
with itself to  the  stomach, and uniting  with the  cardiac
filaments of the cervical ganglion; on  the left side it fur-
nishes only one filament, which terminates in  the  cardiac
plexus.
  4th.   The recurrent or inferior laryngeal nerves.  These
differ on the right  and left sides; the left  turns round the
arch of the aorta;  the  right passes round  the subclavian
artery :  both ascend on the side of the  trachea, and termi-
nate at the larynx. 
96
NERVOUS SYSTEM.
Fig. 28.
  Fig. 28,  exhibits the general course of the deep seated
nerves of the neck and thorax.
  a, the superior cervical  ganglion of the great sympathe-
tic nerve.
  b, the middle cervical ganglion. 
NERVOUS SYSTEM.
97
  c, the pneumo-gastric nerve.
  d, d, the recurrent, or inferior laryngeal nerve.
  I, the pharyngeal nerve.
  t, the superior laryngeal nerve.
  s, the cardiac plexus.
  7i, the coronary nerves.
  k, k, k, the cervical nerves, forming the brachial plexus.
  o, p, the cervical plexus.
  i, the commencement of the phrenic nerve  from the
fourth cervical nerve,   g, its  course over the lungs to the
diaphragm.
  The  pneumo-gastric  nerve gives  filaments to the oeso-
phagus and stomach ;  it also unites by numerous  radiations
with the hepatic, the splenic, the coeliac, and the  right gas-
tro-epiploic plexus : other filaments are interlaced with the
meshes of the solar plexus, and several expand  on the vena
portae, the pancreas, the duodenum, and the gall bladder.
  On account of the very extensive  distribution, and nu-
merous communications of the pneumo-gastric nerve, it is
called by some authors the middle sympathetic nerve.


        ELEVENTH PAIR, OR HYPOGLOSSAL  NERVES.

  The hypoglossal nerve is connected by several filaments
with the fissure  which separates the olivary and  pyramidal
eminences;  these  filaments form a cord, which passes out
of the cranium by the anterior condyloid foramen. The
hypoglossal is then united to the pneumo-gastric nerve for
a short distance, but at the angle of the jaw it is directed
downwards and  forwards, curving under the tendon of  the
digastricus, towards  the tongue.  From the convexity of
the curve it gives  off, —
  The descending cervical branch.   In the former mode of
enumerating the cranial nerves, it was termed  the descend-
   VOL. n.             13 
98
NERVOUS SYSTEM.
ens noni;  it passes in front of the internal jugular vein, and
communicates with the internal branch pf the cervical plex-
us.  The  hypoglossal nerve then passes between the mylo-
hyoideus  and hyoglossus ; it  furnishes branches to the
adjacent muscles, and is finally distributed  to the tongue.
   It gives the power of  motion to the  muscles of the
tongue ;  principally, however, to those concerned in the
process of mastication and deglutition.


    TWELFTH PAIR,  OR ACCESSORY NERVE  OF WILLIS.

   The spinal accessory nerve (called by Sir  Charles Bell
the superior respiratory of the trunk) is singular in its ori-
gin and progress.  It commences at the lateral parts of the
spinal  cord ; the first point of union with the  medulla
spinalis is  about the  sixth vertebra of the cervical region ;
it ascends between the ligamentum denticulatum and pos-
terior roots of the cervical nerves, receiving from the latter
new filaments which increase its size ; it then passes through
the great occipital foramen, and makes its exit by the  for-
amen lacerum posterius with the pneumo-gastric, to which
it sends a  filament; it then leaves the latter and adheres to
the hypoglossal, from  which it again  separates, passes
through the  sterno-cleido-mastoideus  muscle, and  termi-
nates in the trapezius.  Fig.  28, m.
   Recent  investigations have decidedly proved, that the
spinal accessory nerve, both in its commencement and dis-
position, conforms  to  the spinal  nerves, and  is  never
deprived of a posterior root, as some have  imagined.
   This  nerve gives  the power of motion  to the sterno-
cleido-mastoideus, and to  the trapezius. 
NERVOUS SYSTEM.
99
Fig. 29.
  This fio-ure was before given to shew the basis of the
brain, etc.  It is  again  introduced to  exhibit the com-
mencement of the cerebral nerves.  They are numbered,
as they have been described, according to the most modern
arrangement.
  1, the olfactory nerve,  having several  roots behind, and
a bulbous extremity before.
  2, 2, the optic nerves united before, n, the infundibulum.
  3, the common motor nerve.
  4, the  patheticus.
  5, the trigeminus.
  6, the abducens or external motor nerve. 
100
NERVOUS SYSTEM.
    7, the facial nerve, or portio dura.
    8, the auditory nerve, or portio mollis.
    9, the glosso-pharyngeal nerve.
   10, the pneumo-gastric nerve.
   11, the hypoglossal nerve.
   12z the spinal accessory.
     '-■.0

                    SPINAL NERVES.

   The  spinal nerves are divided into four orders, viz. the
cervical, the dorsal, the lumbar, and the sacral.
   The  nerves  of the spinal cord,  which have been pre-
viously  enumerated, commence by  two  species  of  roots.
Each of these roots is formed by a  number of distinct fila-
ments, but in their passage through the intervertebral fora-
mina they unite ; the posterior  root,  at their  union, forms
a ganglion.   See Fig. 12.
   The 1st  order  of spinal nerves are  the  cervical, nine
pairs.
   The 2d order, the dorsal nerves,  twelve pairs.
   The 3d order, the lumbar nerves, five pairs.
   The 4th order, the sacral nerves, six pairs.


           FIRST PAIR OF  CERVICAL NERVES.

   The first pair of cervical nerves commences at the sides
of the spinal cord, beneath its superior enlargement; each
nerve proceeds from the vertebral canal, between the atlas
and dentata, and divides into two parts : the first of  which
is  joined to  the  accessory nerve, and by branches of the
hypoglossal;  it is also  connected  by a  gangliform  root,
with the upper ganglion of the  sympathetic nerve,  and it
gives filaments to muscles connected with the anterior part 
NERVOUS SYSTEM.                101
of the cervical vertebrae.  The second part of this nerve is
distributed to the extensors of  the head and neck, and
forms the occipital nerve.
           SECOND  PAIR OF CERVICAL NERVES.
                                                f
  The anterior branch of this pair of cervical ner«PI passes
between the transverse processes of the two IpKvertebrae,
and divides into numerous  filaments, one^>f^which unites
with the  first  pair;  another  joins  th^superior cervical
ganglion ; a third  is  distributed to ime anterior rectus of
the head ;  a fourth contributes tOfform  a cervical plexus;
and a fifth communicate with the pneumo-gastric nerves.
  The  posterior branch is reflected upwards,  under the
obliquus capitis inferior, traverses the great complexus, and
is distributed to the occipito-frontalis muscle and to the in-
teguments.
    THIRD AND  FOURTH PAIRS OF  CERVICAL NERVES.

  The third and fourth cervical nerves proceed in  similar
directions; the anterior part sending off branches to form
the cervical plexus ;  while the posterior  supplies the mus-
cles and integuments of the back part of the neck.
                   CERVICAL PLEXUS.

  The cervical plexus is situated on the lateral part of the
neck, on a level with the  second, third, and fourth verte-
brae, and is formed by the anterior branches of  the second,
third  and fourth cervical nerves, which communicate and
form  arches, the convexities of which  send off filaments, 
102
NERVOUS SYSTEM.
which  again  unite, and communicate  superiorly with the
first pair; inferiorly, with the brachial plexus.  The cervical
furnishes very many ascending and descending branches.
   1st.  The internal descending branch, formed by two fila-
ments of the second and third  pair, which uniting descends
on the sterno-cleido-mastoideus muscle, and communicates
with the hypoglossal nerve.
  2d.  The phrenic nerve or  the internal respiratory nerve,
is  principally composed of a  branch of the fifth pair, but
receives a filament from the fourth, and two or three from
the brachial plexus ; it descends upon  the  anterior part of
the neck, between the anterior rectus and anterior scalenus
muscles, communicating with the inferior cervical ganglion,
and passing into the  thorax between the subclavian artery
and subclavian vein ;  it  enters the  anterior  mediastinum,
then descends between the pleura  and  the lateral parts of
the pericardium, and terminates in  numerous  filaments
which  ramify  on  the superior surface  of the diaphragm.
See Fig. 28, i, g.
  3d.  The external descending  branches  of the  cervical
plexus, are distributed in numerous filaments to the mus-
cles and integuments  of the mastoid, auricular, and scapu-
lar  regions.  Some are superficial,  others  deep.   The
superficial descend to the  clavicle  and acromion process,
supply the superficial muscles in their course, and terminate
in  the pectoral and deltoid muscles, and in the integuments.
The deep branches descend  behind  the clavicle, supply the
deep muscles on the side of  the neck, and  those connected
to  the scapula.   One  of these branches, remarkable for its
length, and of the same size of the phrenic,  is named the
external respiratory nerve.  This nerve  proceeds  from the
back part of the  plexus, chiefly  from  the fourth cervical.
It  has also filaments connecting it to the third and second
and to the phrenic.  It  descends behind the scaleni mus-
cles and beneath the trapezius and levator anguli scapulas, 
NERVOUS SYSTEM.
103
and is almost exclusively distributed to the serratus magnus
muscle.
  4th. The superficial ascending branches are derived prin-
cipally from the third  pair;  they are distributed to the
sterno-cleido-mastoideus, the  platysma myoides, the skin
of the neck, and the inferior  maxillary region, and  com-
municate with the facial nerve.


FOURTH, FIFTH, SIXTH, AND SEVENTH PAIRS OF CERVICAL
                        NERVES.

  The posterior branches of these nerves descend obliquely
outwards, traverse the splenius  and trapezius, and are dis-
tributed  to  the muscles and integuments of the back part
of the neck.
  The anterior branches furnish filaments which communi-
cate with the cervical ganglia, and some others which are
distributed to the scaleni muscles :  they then communicate
and form the brachial plexus.   It may be  observed, that a
filament of  the  fourth contributes to the formation of the
phrenic nerve.


            BRACHIAL  OR AXILLARY PLEXUS.

  The brachial  plexus  consists  of an interlacement of the
anterior branches of the last four cervical  nerves  and the
first dorsal.   The brachial plexus  extends from the lateral
and inferior part of the neck to the axilla, where it divides
into several  branches, which are distributed to the thorax,
shoulder and arm.   It is situated between the scaleni mus-
cles, and above the subclavian artery. 
104
NERVOUS SYSTEM.
                  THORACIC  BRANCHES.

   The anterior thoracic branch is chiefly derived from the
seventh cervical nerve ; it descends behind the clavicle, and
divides into numerous filaments, some of which surround
the axillary artery, others descend  on  the chest  and are
distributed to the pectoral muscles.
   The posterior thoracic  branch is  furnished by the  sixth
and seventh cervical nerve;  it descends on the  sides of the
thorax, and is distributed to the serratus magnus.
   The supra scapular branch is supplied by the 5th nerve ;
it descends obliquely backwards towards  the upper  edge
of the scapula,  passes under  the  ligament which converts
the coracoid notch into a foramen, and after giving a branch
to the subscapularis muscle, it passes into the infra-spinatus
fossa, where its ramifications  are lost in the  infra-spinatus
and teres major muscles.
   The sub-scapular branches commence at variable points
of the brachial plexus ; they descend behind the axillary
vessels and  are distributed  to  the  muscles  under the
scapula, and in the teres major and minor.


                 NERVES OF THE ARM.

             INTERNAL CUTANEOUS NERVE.

  The internal cutaneous  nerve is the  smallest  of the
branches which terminate the brachial plexus, from the
lower part  of  which it proceeds ; namely, from  the last
cervical and the first dorsal;  it descends along the internal
surface of the arm, under  the brachial aponeurosis, near
the basilic vein, and divides at the internal condyle of the
os brachii into two branches.   The external  branch passes 
NERVOUS SYSTEM.
105
along the border of the biceps towards  the wrist, where  it
is  distributed  to  the  integuments.   The  internal branch
descends on the  brachialis internus, supplies  the integu-
ments of the back part of the fore-arm,  and  finally ter-
minates at the back of the hand and the little finger.


 EXTERNAL  CUTANEOUS  NERVE, OR MUSCULO-CUTANEOUS.

   The external cutaneous  nerve  is derived from the fifth
and sixth cervical nerves ; it proceeds through the fibres  of
the coraco-brachialis  muscle, (from which  circumstance  it
is  named the perforans casserii,) and  descends along the
anterior part of the arm, between the biceps and brachialis
internus, towards the wrist, where  it divides into  two
branches ; an  external, which sends branches to the back
of the fingers; an internal,  which is  distributed to the
thumb and  the palm of the hand;—and a multitude  of
filaments from this nerve may be traced to the fingers.
VOL. II.
14 
106
NERVOUS SYSTEM.
   Fig. 30, exhibits some
of the principal nerves of
the front of the arm.
  a, b, c, d, the  axillary
plexus.
  e, the ulnar or cubital
nerve.
  f the median nerve.
  g, the radial nerve.
  h, the internal cutane-
ous nerve.
  i, the articular nerve. 
NERVOUS  SYSTEM.
107
THE  MEDIAN  NERVE.
  The median nerve is  the  largest of the brachial plexus ;
it is principally formed by the two lower cervical and the
first dorsal nerves.   De-
scending behind the in-
ternal part of the biceps,
on the inner side of the
brachial  artery, and dip-
ping between  the  bra-
chialis  internus and po-
nator teres, it descends
along the fore-arm, be-
tween the superficial and
deep seated flexor  mus-
cles.  It  then proceeds
under  the annular liga-
ment of  the carpus, and
divides in the  hand into
digital filaments, which
are distributed to the fin-
gers.   Before  this  divi-
sion, however, it furnish-
es considerable branches
to the  muscles  of the
fore-arm.
   Fig. 31,  exhibits the
distribution of the  prin-
cipal  branches  of the
median  nerve  on  the
fore-arm.
   a,  the trunk  of the
median nerve.
3063 
108
NERVOUS SYSTEM.
   b, a branch given to the supinator muscles.
   c, a branch to the interosseous ligament, and to the flex-
or profundus muscle.
   d, the ulnar nerve cut off.
   e, the palmar  branch given  to  the  integuments of the
hand.
  /, a branch to the pronator muscles.


                    ULNAR  NERVE.

   The ulnar nerve proceeds from the last cervical and first
dorsal  nerves, and descends along the internal border of the
triceps, supplying  this muscle  and the upper part of the
fore-arm with numerous filaments ; then passing between
the inner condyle of the humerus and the olecranon, gives
many branches to the flexor carpi  ulnaris,  and descends
along the anterior and internal part of  the fore-arm, divid-
ing near the wrist into two branches, the palmar and  the
dorsal.   The former is  directed on the outer part of the
tendon of the flexor-carpi ulnaris, on  the  side  of the os
pisiforme, and divides into  the deep,  the  superficial, the
external, and the internal branches, which are distributed
to the fingers.  The latter, or dorsal, gains the internal part
of the back of the hand, and divides into internal branches,
which  are  extended to the corresponding  surface of the
middle, the ring finger, and the little finger. 
NERVOUS SYSTEM.                109
  Fig. 32, exhibits  the  dis-
tribution of  the  principal
branches of the ulnar nerve.
  a, the ulnar nerve perfo-
rating the heads of the flex-
or muscles.
  b, c, branches distributed
to the common extensor  of
the fingers.
  d, a branch distributed  to
the interosseous ligament.
  e, a branch distributed  to
the wrist and the back of the
hand.
Fig. 32.
RADIAL NERVE.
  The radial or muscular spiral nerve, has the same deriva-
tion as the preceding ;  it descends between the middle and
the short portions of the triceps muscle, turns round the
os brachii to the external part of the arm, and at the elbow
joint  divides into  two  branches; the anterior which de-
scends between the two supinator muscles, and is distribu-
ted to the thumb, and the inner side  and back of the fore 
110
NERVOUS SYSTEM.
finger, and the outer side of the middle finger.   Its poste-
rior branch is  divided into filaments, which are distributed
to the superficial muscles of the fore-arm.


                  CIRCUMFLEX NERVE.

  The circumflex, or articular nerve, is usually formed  by
the two last cervical and the first dorsal nerve; it descends
in front of the subscapularis  muscle,  to which it  gives a
branch, and turns backwards, between the superior part of
the os brachii and the  long  portion of the triceps: it is
ultimately distributed to the internal surface of the deltoid
muscle, near its  insertion in the os brachii.


                    DORSAL NERVES.

  The dorsal nerves, or those which are transmitted  by the
intervertebral  foramina of the dorsal region, like  the cervi-
cal nerves, proceed  from  the lateral  parts of the spinal
marrow by two  distinct roots, an anterior  or small, and a
posterior or large, separated by the ligamentum denticula-
tum.   Beyond the intervertebral foramen, the double roots
are united into a single trunk, and a small gray and hard
ganglion is formed by the posterior roots.  These nerves
divide into dorsal and intercostal branches.
  The dorsal  branches pass backwards between  the trans-
verse processes of the dorsal vertebrae, and are distributed
to the muscles and integuments of the back and loins.
   The intercostal branches, near their commencement, re-
ceive a filament  from each thoracic ganglion, pass outwards
between the ribs, covered by the pleura, as far as the angle
of these bones, where  they  are found  between the two
strata of intercostal  muscles.  The anterior branch of the 
NERVOUS SYSTEM.
Ill
second follows the internal  surface of the second rib, and
sends off a brachial  filament, which pierces  the  external
intercostal muscle, and descends along the posterior and in-
ternal part of the arm, and  is lost at the  elbow: this is
named the nerve of Wrisberg.   The anterior branches of
the fourth to the eleventh dorsal  nerve, proceed along the
inferior margin of the corresponding ribs, and are  distribu-
ted to the muscles and  the integuments of their  different
regions.   The anterior  branch of the  twelfth, at its com-
mencement, communicates by a filament with the first lum-
bar nerve, and is afterwards distributed to the muscles and
the integuments of the abdomen.


                    LUMBAR NERVES.

   The lumbar  nerves, or those which  are  transmitted by
the intervertebral foramina of the lumbar vertebrae, consist
of five pair ; commencing by two  broad  fasciculi of fila-
ments, which the older writers termed cauda equina, from
the resemblance they bear to the tail of a horse ; especially
when the nervous fibres are unravelled, and separated from
each other.
   The anterior branches of the  five  lumbar nerves form,
by their union, the lumbar plexus, which is situated behind
the psoas muscle, on the lateral parts of the bodies of the
second, third, and fourth lumbar  vertebrae.


                 FIRST  LUMBAR  NERVE.

   The posterior branch of this nerve is distributed to the
multifidus spinae, traverses  the sacro-spinalis muscle,  and
passing under the aponeuroses of the abdominal  muscles,
finally ramifies in the integuments of the upper part of the
hip. 
112
NERVOUS SYSTEM.
  The anterior branch receives a communicating filament
from the lumbar ganglia, and from the twelfth dorsal nerve,
and terminates in the lumbar plexus.


                SECOND  LUMBAR NERVE.

  The posterior branch of this  nerve takes nearly the same
course as the  former, and is expanded by a great number
of subdivisions on the upper and back part of the thigh.
  The anterior branch has extensive communications  with
the lumbar ganglia, the anterior  branches of the first and
second  pairs of the lumbar region, and with the lumbo-
abdominal plexus.


                 THIRD LUMBAR NERVE.

  The posterior branch is distributed precisely in the same
manner as the former.
  The anterior branch  communicates with the second and
the fourth lumbar nerves, giving  contributions as the pre-
ceding.


          FOURTH AND FIFTH LUMBAR NERVES.

  The posterior and anterior branches have a similar distri-
bution to those  just described; some filaments, however,
of the latter  are  continued into  the pelvis, to  unite with
the sciatic plexus. 
NERVOUS SYSTEM.
113
          LUMBO-ABDOMINAL, OR LUMBAR PLEXUS.

   This plexus  is  formed by  the  union of the anterior
branches of the  five lumbar  nerves ; it is situated  on the
lateral parts of the bodies of the  second, third, and fourth
lumbar vertebrae, behind the psoas magnus.  It terminates
in the musculo-cutaneous, the genito-crural, the crural, the
obturator, and the lumbosacral nerves.


             MUSCULO-CUTANEOUS BRANCHES.

   These branches are commonly three in number;  1st, the
superior, proceeding from the first lumbar nerve, descends
on the quadratus lumborum as far as the crest of the ilium,
pierces the transversalis muscle, and ramifying in the mus-
cles  and integuments of the abdomen, and extending to
the abdominal ring, is distributed to the groin, the pubic
region, the scrotum in the male, and the labia pudendi in
the female.  2d, the middle branch  descends on the outer
margin of the psoas muscle, perforates  the  transversalis
and is distributed  to the cellular tissue of the  abdomen ;
one filament is transmitted to the superior part of the scro-
tum.  3d, the inferior branch extending from the second
lumbar nerve, and passing out of the pelvis, between the
superior and the inferior spinous processes of the ilium, is
distributed to the posterior superior part of the thigh.  An
internal filament pierces the fascia lata and descends to the
external part of  the knee.
   VOL. II.              15 
114
NERVOUS SYSTEM.
                GENITO-CRURAL NERVE.

  This nerve proceeds from the first lumbar nerve;  it de-
scends in the substance of the psoas muscle, and afterwards
divides  into  an internal branch, which accompanies the
spermatic cord; and an external, which, at the crural arch,
is distributed in a multitude of filaments in the subcutane-
ous cellular tissue.


                    CRURAL NERVE.

  This nerve commences at the first four lumbar nerves ;
it passes out of the abdomen under the crural arch, on the
outer side of the femoral artery, and then divides into deep
seated and  superficial branches.
  1st. The superficial  branches perforate the fascia lata,
and are distributed in the integuments  of the anterior and
inner part of the thigh,  descending as  far as the superior
part of the leg.
  2d. The deep seated branches divide  into numerous fila-
ments, which are  distributed to the iliacus, the  sartorius,
and  the triceps extensor  cruris muscles.  The  internal
branches supply the muscles on the corresponding part of
the thigh ;  one of  these, more  conspicuous than  the other
branches, termed the  internal saphena nerve, accompanies
the vena saphena in all its divisions to the great toe. 
NERVOUS  SYSTEM.
115
  Fig. 33, exhibits  the prin-
cipal  nerves  of the front of
the thigh.
  a,  a branch  of the  first
lumbar nerve.
  6, a branch of the second
lumbar nerve.
  c,  the crural nerve, with
its divisions into the branches
which supply the front of  the
thigh.
  d, a branch to the triceps
extensor cruris muscle.
  e,  e,  the  saphena  nerve,
sent from the crural nerve to
the inner part of the leg.
  f  the external  cutaneous
nerve.
  g, the femoral artery.
  h, the anterior   obturator
nerve.
Fis. 33.
OBTURATOR  NERVE.
  This nerve issues principally from the second, third, and
sometimes  from the fourth, lumbar nerves; it descends on
the inner margin of the psoas muscle, gives  a branch  to
the obturator muscles, traverses the obturator  foramen, 
116
NERVOUS SYSTEM.
and between the pectineus and first adductor, divides into
two  branches.   1st.  Its  anterior  branch distributed  to
the little adductor  and  vastus internus.  2d.  Its  pos-
terior branch to the great adductor and external obturator
muscles.
                 LUMBO-SACRAL  NERVE.

  This nerve is derived from the fourth and fifth lumbar
nerves ; it descends into the  pelvis,  and unites with  the
sciatic plexus.  In  its  course it furnishes a  single branch,
which is the glutaal nerve.
                    GLUTJEAL NERVE.

  This nerve derives some roots from  the  sciatic plexus;
it passes out of the sciatic notch, and divides into a multi-
tude of branches, which are distributed to the glutaei mus-
cles, the perineum and the  subcutaneous cellular tissue at
the back of the thigh.


                     SACRAL NERVES.

  The sacral nerves issue from the sacral canal; they con-
sist of five or six pairs, derived from the inferior part of the
spinal cord.  Their posterior  branches  supply the various
muscles  in  their vicinity; while the anterior branches of
the  first four  sacral, with those of the fifth lumbar, form
the  sacral or  sciatic plexus.   These  branches, again
uniting,  form a large nerve, termed  the sciatic nerve.  It
also furnishes the  hamorrhoidal,  the vesical, the uterine,
and the  vaginal nerve  (which are  small  and interlacing 
NERVOUS SYSTEM.
117
with each  other) ;  and  the  inferior gluteal  and pudic,
which are distributed to those parts the several names in-
dicate.
                    SCIATIC NERVE.

  The sciatic nerve terminates  the plexus of  the  same
name, and is the largest of all the nerves of the body ; it
passes out of the pelvis by the sciatic notch, between the
pyramidalis and superior gemellus, and descends along the
posterior part of the thigh  as  far as the ham,  where it di-
vides into two branches,  termed the popliteal.  As the
sciatic nerve proceeds down the leg, it furnishes filaments
to the adjacent muscles, and to the integuments.


             EXTERNAL POPLITEAL  NERVE.

  This  nerve has  also the  name  of fibular, or peroneal
nerve; it descends behind  the external  condyle of the fe-
mur, and  passes  between the fibula and  the peroneus
longus muscle, and divides  into the musculo-cutaneous,
and the anterior tibial.  The musculo-cutaneous, or external
fibular nerve, descends between  the peroneus longus, and
the extensor digitorum pedis, and afterwards between this
latter and the  peroneus brevis.  Towards  the middle of
the leg  it becomes  superficial, and  divides near the foot
into filaments, which are  distributed to the back of the
foot and to the toes.
   The anterior tibial nerve descends in front of the inter-
osseous ligament, ramifies in the extensor brevis digitorum
pedis, and gives filaments to the first two toes. 
118
NERVOUS SYSTEM.
              INTERNAL POPLITEAL NERVE.

   This nerve is  larger than the preceding, and descends
into the ham, passing behind the articulation, and between
the heads of the  gastrocnemii  and the popliteus muscles,
then between the latter and  the soleus  muscle ; there it
passes through the arched aperture which that muscle pre-
sents, and takes the name of the tibial nerve.  This nerve
descends  between the  soleus  and tibialis posticus posteri-
orly, and  the flexor longus digitorum pedis anteriorly, and
is closely  connected  with the  posterior tibial artery :—be-
neath the os calcis it divides into the external and internal
plantar nerves.  The tibial nerve furnishes, above the ex-
ternal  condyle of the  femur,  the external  saphena  nerve.
In  the ham it  supplies filaments  to  the  muscles of the
superior  part of  the leg,  and to the articulation  of the
knee;  to the  interosseous ligament and to the anterior
muscles of the leg.  Near the  inner  malleolus,  it sends a
filament to the sole of the foot.
   The internal plantar branch  proceeds  directly forwards
above the adductor  proprius  pollicis pedis, and is  distri-
buted to the internal part of the foot and  to the toes.
   The external plantar branch is directed forwards and out-
wards, and is distributed to the external border of the foot
and to the interosseous muscles. 
NERVOUS SYSTEM.
119
  Fig. 34, exhibits the princi-
pal nerves of the  back part of
the thigh.
  a, the sciatic nerve, passing
out of the pelvis.
  b, the posterior  superior cu-
taneous nerve.
  c, the  trunk of the sciatic
nerve, sending branches to the
muscles of the back part of the
thigh.
  d, the division of this nerve
into,—
   e, the tibial nerve, and,—
  f the fibular nerve.
Fig. 34.
 
120              NERVOUS SYSTEM.
                      CHAP. II.

  GANGLIONIC DEPARTMENT OF THE NERVOUS SYSTEM.

  It has been before remarked in this work, that in the in-
fancy of anatomy the term " ganglion" was used to denote
a swelling in the thecae of tendons, and even at the present
day it is not unfrequently employed in the same sense.   It
was subsequently applied to the knotted  appearance pre-
sented by certain nerves, but of late years a considerable
latitude has been given to its  signification by Gall  and
Spurzheim,  who include within its  comprehension, the
several  masses of cineritious substance inclosed within the
medulla and brain, and  which according to their theory,
are considered " ganglia of increase" to the formative fibres
of the  cerebral  hemispheres.  Ccj^The  term " formative
fibres" will be explained at the  termination of the article
on the nervous system.
  Nervous ganglia may be divided into two orders.   1.
Those observable on the posterior roots of the  cerebro-
spinal  nerves, including  that of the  fifth nerve ; 2. The
ganglia of the sympathetic.
  The ganglia are small  nervous centres, (see Fig. 35, and

            Fig. 35.                    Fig. 36.
36,) which some anatomists have designated by the appel-
lation of " diminutive brains."  They extend from the era-
 
NERVOUS SYSTEM.
121
nium to the pelvis, mostly lying along the vertebral column,
and presenting  a series connected  by nervous  filaments,
each ganglion being considered by most physiologists as  a
special  centre of nervous influence.
   The  forms of the ganglia are very irregular; in general
they are somewhat round ;  occasionally they are elongated ;
in  other instances they are of a semilunar form, as that
which bears  this name.   In general all their forms, as  I
have just noticed, are remarkably irregular.
   Each ganglion transmits nerves upwards and downwards
to the ganglia which are contiguous ; and other nerves to
the cerebral or spinal nerves.  The greater part, however,
of the nervous filaments radiating from the ganglia are in-
terwoven, in the form  of  a net-work or plexus; the most
remarkable of which is the solar plexus, which is formed
by the innumerable nerves proceeding  from the semilunar,
the hypogastric, and the  cardiac ganglia.  The filaments
of the ganglia, as it were, exchange  their connections and
their direction, and form  angles  and meshes  so  intricate
that it is not possible to distinguish anything more than a
mass  of nerves.
   The ganglia are amply supplied with  blood-vessels which
penetrate them on all sides, ramifying on their surface and
uniting in their interior.
   The cerebro-spinal department of  the nervous system is
the immediate agent of the will, whilst the ganglionic de-
partment presides altogether out of the influence of the will
of the individual.   Thus,  for example,  the heart contracts
without our possessing the power of accelerating or retard-
ing its  movements, in any sudden way, according to our
will;  the stomach in like manner  acts on the aliments, and
digests them without our being able to exercise any control
over its  operations ; and for this  reason, these organs are
under the  direction of the ganglionic department of the
nervous system.
   VOL. II.              16 
122
NERVOUS SYSTEM.
            PARTICULAR  GANGLIA.

                  GANGLIA OF THE HEAD.

               '  LENTICULAR GANGLION.

   The lenticular ganglion is  situated on the external side
of the optic nerve, near its entry into the orbit; its form is
oblong and very small.   Posteriorly, it receives a filament
from the nasal branch of the ophthalmic, and one from the
third nerve ;  anteriorly, it furnishes the ciliary  nerves.
  The ciliary nerves are very delicate,  and are divided into
two fasciculi; the superior fasciculus  is formed of six fila-
ments, which extend to  the globe of the eye above  the
optic nerve.  The inferior fasciculus is composed of eight
or ten nervous filaments, which  proceed on the outer and
inferior part of the optic nerve.
  These nerves,  consisting of from twelve to  seventeen,
pass obliquely  through  the sclerotica, and proceed in a
parallel direction  between  the  latter  membrane  and  the
choroid,  and, reaching  the  ciliary circle, each  filament
subdivides  and is extended to  the ciliary ligament and
the iris.
              SPHENO-PALATINE  GANGLION.

  This ganglion, denominated also the ganglion of Meckel,
is a small triangular  reddish body ; it is not very readily
discovered, being concealed in  the  adipose cellular tissue
of the pterygo-maxillary fissure.  This ganglion furnishes
the following branches : —
  The ascending branches, two in number, which  pass up-
wards, and join the superior maxillary, or second branch of 
NERVOUS SYSTEM.
123
the fifth pair, previously to its entrance into the infra-orbi-
tar canal.
   The spheno-palatine nerves, varying in number from three
to five ; they pass into the nasal fossa by the spheno-pala-
tine foramen.   Two or three filaments  ramify on the con-
cave  surface of the  superior turbinated bone, and in the
corresponding meatus ; some extend to the middle turbina-
ted bone, and others are distributed to the posterior part
of the septum narium.   The most considerable  filament,
termed the naso-palatine, is directed to the superior part of
the septum, and terminates in the naso-palatine ganglion.
   The palatine nerves are, 1st, the great or inferior pala-
tine, which  furnishes a filament  to the middle and inferior
turbinated bones; it afterwards  enters  the  posterior pala-
tine canal, and before its exit gives another filament to the
nasal fossae, which is lost on the ascending  process of the
superior maxillary bone.   Other filaments are distributed
to the velum palati, the arch of the palate, the alveoli, and
the gums.
   2d. The middle palatine nerves, which are distributed to
the amygdalae and to the velum palati.
   3d. The  lesser palatine nerves, which  are  situated be-
tween the external pterygoid muscle and the superior max-
illary bone ; they are destined for the tonsils and the mucous
follicles of the membrane of the palate.
   4th.  The Vidian nerve leaves  the spheno-palatine gangli-
on and enters the pterygoid canal, giving  filaments to the
adjacent  parts;  then divides into two  branches, 1st, the
inferior or carotid branch, which descends into the carotid
canal, and unites with the superior cervical ganglion.   2d.
The  superior branch, which  takes  rather  a  complicated
course, enters the cranium between the petrous portion of
the temporal  and  the  sphenoid  bones, and  is  directed
backwards  and outwards  on the  superior surface of the
former bone, where it  is lodged  in a  small  groove cov- 
124              NERVOUS SYSTEM.

ered by the  inferior maxillary nerve and the dura mater;
it then passes with a small artery into the hiatus fallopii,
and, on arriving at the aqueduct of Fallopius,  is found in
apposition with the facial nerve.   It then  penetrates  the
cavity of the tympanum, where it  is denominated the corda
tympani; above the tensor tympani it  enlarges, and is di-
rected downwards and forwards, passes out  of the glenoid,
or Glasserian fissure, and is attached to the lingual branch
of the inferior maxillary nerve.  Opposite the submaxillary
gland it separates from it to proceed to  the ganglion of  the
same name.

                         Fig. 37.
  Fig. 37, exhibits the course of the corda tympani, on the
left side.
  a, the facial nerve in the aqueduct of Fallopius.
  b, the Vidian nerve communicating with the facial in the
aqueduct of Fallopius.
  c, a filament of the facial given to the laxator tympani.
  d, a filament given to the muscle of the stapes.
  e, the corda tympani, separating from the facial, passing 
NERVOUS SYSTEM.
125
through the cavity of the tympanum, and uniting with, g,
the inferior maxillary nerve.
  Besides those before described, the following ganglia are
met with in the head, namely —
  The cavernous ganglion, situated on the outer side of the
internal carotid artery in the cavernous sinus.
  The naso-palatine ganglion, situated in  the anterior pala-
tine foramen.
  The submaxillary ganglion, occurring on a level with the
submaxillary gland, and apparently formed by the superior
filament of the Vidian nerve.


                  GANGLIA OF THE NECK.

  SUPERIOR, OR GREAT  CERVICAL  GANGLION.  Fig. 28, a.

   This ganglion is  found under  the  angle of the inferior
maxilla, and is remarkable for its size and the regularity of
its occurrence; it  is of a reddish gray color and is inti-
 mately united to the  pneumo-gastric  and  hypoglossal
 nerves.   It lies on the rectus anticus muscle, concealed by
 the jugular vein and carotid  artery.  A number of nervous
 filaments issue from it, which are  distinguished into supe-
 rior, inferior, external, and anterior.
    The superior or ascending filaments  ascend  into  the
 carotid canal, and unite with the  superior filament of the
 Vidian nerve, with  the sixth pair in the cavernous  sinus,
 with a filament from the glosso-pharyngeal,  and by other
 filaments with the ophthalmic and nasal branches.
    The inferior or descending filaments pass in front of the
 anterior  recti and longus  colli muscles, covered by the
 carotid artery, the  jugular  vein, the pneumo-gastric, and
 the hypoglossal nerves, and terminate on a  level with the
 fifth or  sixth vertebra in  the middle cervical  ganglion. 
126
NERVOUS SYSTEM.
Filaments from  the superior ganglion  unite  with the ex-
ternal laryngeal  nerve, and others which  enter the  thorax
concur in forming  the  cardiac  plexus.   The external, in-
ternal, and anterior filaments, communicate with nerves in
their vicinity ; thus the  first unites with the cervical nerves,
the second with  the  pneumo-gastric, forming the pharyn-
geal plexus;  and the third with the pneumo-gastric and
the facial  nerves,  forming a  plexus  upon  the  primitive
carotid :  finally, the latter filaments of the superior cervical
ganglion unite to form the superior cardiac nerve.


        MIDDLE CERVICAL GANGLION.   Fig.  28, b.

  This  ganglion varies extremely in  size, and, indeed, is
not constantly found ; it is situated  opposite the fifth or
sixth cervical vertebra,  and before the carotid artery and
jugular vein.  Its anterior filaments form the middle car-
diac nerves.
             INFERIOR CERVICAL GANGLION.

  This ganglion is frequently continuous with  the middle
cervical ganglion ; it  is  situated behind the  vertebral ar-
tery, between the transverse process of the  seventh ver-
tebra, and the neck of the first rib.   Numerous filaments
issue  from this ganglion, which  unite with the cervical
nerves, the first thoracic ganglion, and the  inferior cardiac
nerves.
           CARDIAC NERVES.   Fig. 28, 71.

These nerves are  particularly destined  to  supply the 
NERVOUS SYSTEM.
127
heart: there are three on each side, which terminate in the
cardiac plexus.
  The superior cardiac nerves, on the right side, are formed
by five or six filaments which  proceed from  the  superior
cervical ganglion ; they descend on the side of the trachea,
penetrate the thorax  behind the subclavian  vein and re-
ceive filaments from the inferior cervical ganglion, and the
recurrent nerve of the pneumo-gastric.  Those of the left
side are situated between the primitive carotid and the sub-
clavian arteries, and proceed on the aorta to unite with the
inferior cardiac nerves.
  The middle cardiac nerves, on the right side, proceed by
five or six filaments  from the  middle cervical ganglion ;
these descend near  the primitive carotid, uniting with the
recurrent, and terminating in  the cardiac plexus.  That of
the left side receives its principal filament from the inferior
cervical ganglion, and descends  behind the subclavian ar-
tery and the arch of the aorta.
  The inferior  cardiac nerves, on the  right side, descend
from the inferior  cervical ganglion, and  proceed on the
anterior part of the arch of the aorta, as far as the cardiac
plexus.
  The middle, and the inferior cardiac nerves, on the left
side, are united into a single trunk.


       CARDIAC  PLEXUS,  OR GANGLION.   Fig. 28, S.

  The cardiac plexus is  situated behind  the arch of the
aorta,  and consists of a central point of union of the car-
diac nerves,  a  great  number  of which  issue  from it, and
others are connected with it in every direction : some ram-
ify on the aorta; others terminate in the pulmonary plexus ;
several are distributed to the pulmonary artery ; and a con-
siderable nerve interlaces its filaments in  the  direction  of 
128
NERVOUS SYSTEM.
the posterior coronary artery, forming the coronary plexus.
Filaments also proceed  in  the direction of  the  anterior
coronary artery, and are therefore denominated the anterior
coronary plexus.
                  THORACIC  GANGLIA.

  These ganglia are  smaller than  the  cervical ganglia; —
there are twelve on each side, disposed  in the same line in
front of the head of  each rib.   Their form and size resem-
ble  grains of barley  ; they communicate by  vertical  fila-
ments  with each other, and  furnish  also  external  and
internal  filaments : the  former unite  with  each  of  the
branches of the dorsal  nerves, at  the point of their  exit
from their foramina; the latter concur in the formation of
the splanchnic  nerves.


                  SPLANCHNIC NERVES.

  There are two  splanchnic  nerves on each side, distin-
guished into the great and small.


               GREAT SPLANCHNIC NERVE.

  This  nerve  is connected  with the internal part of the
sixth, seventh, eighth,  ninth, and  sometimes  the tenth
thoracic ganglia, by filaments which  descend on  the sides
of the vertebral column, and unite into a single trunk, on a
level with the eleventh dorsal vertebra : this nervous cord
enters the abdomen, passes  behind  the  stomach, and ter-
minates in the semilunar ganglion. 
NERVOUS SYSTEM.
129
               SMALL SPLANCHNIC NERVE.

  This nerve is  formed of two branches from  the tenth
and the eleventh thoracic ganglia ;  these branches unite into
a small cord on the twelfth dorsal vertebra, enter the abdo-
men, and, communicating with the former, terminate in the
renal ganglion.


                GANGLIA OF THE ABDOMEN.

         SEMILUNAR GANGLIA AND SOLAR PLEXUS.

  The semilunar  ganglia are two in  number, situated on
each side of the aorta, on a level with the cceliac artery;
they are  larger than any other ganglia, and  have a form
somewhat corresponding  to the name.  The  superior and
external  extremity  of each ganglion  receives the great
splanchnic nerves ; by the inferior they form a communi-
cation  with each  other.  The two semilunar  ganglia are
surrounded by a  multitude of other smaller ganglia, com-
municating with them by short filaments, which issue from
their circumference ; and the secondary ganglia also are
united to each other by  very numerous filaments, which
form areolae.   It  is this remarkable assemblage of ganglia,
and  interlacing of nervous filaments,  that constitutes the
SOLAR  PLEXUS.
  The plexus  just named, appears to be particularly des-
tined for the  aorta, being distributed to all its divisions,
and following all its immediate branches with a correspond-
ing number of secondary plexuses, such as,—
  1. The sub-diaphragmatic plexus, which is  composed of
a small number of filaments, which unite with  the phrenic
nerve and are distributed to the diaphragm.
  VOL. n.              17 
130
NERVOUS SYSTEJI.
   2. The cceliac plexus is merely a prolongation of  the
 solar plexus, upon the  triple division of the cceliac artery;
 —it is  composed of several ganglia, varying in  form and
 size.
   3.  The hepatic plexus  is associated with  the  hepatic
 artery  and the vena portae; — it follows  their principal
 divisions.
   4.  The splenic plexus follows the course of the splenic
 artery,  and is distributed to the spleen.
   5.  The superior mesenteric plexus descends with the su-
 perior mesenteric artery, and forms a web of great extent,
 the filaments of which are distributed to  the  lymphatic
 glands of the mesentery, and follow the ramifications of the
 artery, so as to cover the whole surface of the small intes-
 tines.   This plexus also furnishes  nerves to the ascending
 colon and ccecum.
   6.  The inferior mesenteric plexus accompanies the infe-
 rior mesenteric artery,  enters  the  iliac mesocolon, and is
 distributed to the adjacent parts.
   7.  The renal plexus commences by several ganglia, situ-
 ated on the renal artery, and is distributed to the  substance
 of the kidney.
   8.  The surrenal plexus is found at the  commencement
 of the capsular artery, and supplies the part which the name
 implies.
   9.  The spermatic plexus  descends from  the renal, and
 follows  the direction of the spermatic artery, to the testicle
in the male, and to the  ovarium and the Fallopian tube in
 the female.
                 THE LUMBAR GANGLIA.

  These ganglia are situated on  the anterior and lateral
parts of the bodies of the lumbar vertebrae : they are com- 
NERVOUS SYSTEM.
131
monly five in number on each side, and have  communica-
ting nervous branches, and external and internal filaments,
which contribute to supply the adjacent organs, and are
united with the sacral ganglia.


                 THE SACRAL GANGLIA.

  There are three or four of these ganglia found on each
side of the anterior  foramina of the sacrum ; they commu-
nicate with the lumbar  ganglia, and contribute to form the
hypogastric plexus.


                 HYPOGASTRIC PLEXUS.

  This plexus is composed of numerous filaments from the
vesical,  uterine, vaginal, and haemorrhoidal  nerves  of the
sciatic plexus.  The hypogastric plexus distributes its ram-
ifications to the organs of generation (within the pelvis),
to the os coccygis, and to  the rectum. 
132
NERVOUS SYSTEM.
Fig. 38.
  Fig. 38, exhibits some of the principal nervous  ganglia
and plexuses of the thorax and abdomen, on the left side,
and the pneumo-gastric nerve, on the same side.
  a, a, thoracic ganglia.
  b, the pneumo-gastric nerve.
  c, a branch of the former, called  the inferior laryngeal
or recurrent, curving round the arch of the aorta. 
NERVOUS SYSTEM.
133
  d, the oesophageal plexus.
  e, the pericardium.        /, the lungs.
  r, the pulmonary plexus.
  g, the diaphragm.         h, the spleen.
  i, the stomach.
  The two last named organs are turned  to  the  opposite
side to shew the distribution of the  nerves.
  k, the kidney.             I, the abdominal aorta.
  m, the semilunar ganglion, and solar plexus, the latter
radiating to all the divisions of  the aorta.
  n, the splenic plexus.      o, the pancreas.
  p, p, p, the lumbar ganglia.
  q, the obturator nerve.

                                         f
         THE TERM GREAT SYMPATHETIC NERVE.

  After studying this department of the  nervous  system,
we  can see the  reason why it is usually denominated, the
great sympathetic nerve. It is in fact a collection of filaments
from every nerve in the animal fabric, which join each other
at the adjacent ganglia.   It  seems  to spring  from  the
sixth nerve, and from the  Vidian branch of  the fifth,  and
is reinforced by filaments from the seventh, eighth, ninth,
and all the spinal nerves, to the lumbar region, and termi-
nates in the pelvis.
  This name, which  has  been  given  to  the ganglia  and
their nervous radiations, expresses the conviction of anato-
mists,  that its office is to associate the affections of differ-
ent  parts.  And we cannot doubt that  this department
directs and controls  the actions, and  endows organic life,
or the parts within, with its due sensibilities ; the visceral
sensations  are always involuntary;   they  are  generally
vague, confused,  and usually  more or  less fugitive,  and
do  not, for any length of time, become fixed in the mind. 
134
NERVOUS SYSTEM.
If our internal organs act according  to the ordinary laws
of organization, the sensations which  arise from them are
agreeable, and the  healthy actions  may give us the most
vivid pleasure ; but if the actions of our functions are in-
terrupted, if our organs are wounded or diseased, the in-
ternal sensations are painful, and according to the disorder-
ed state, or the injury, they assume a different character.


FORMATIVE FIBRES  OF  THE BRAIN  ACCORDING TO GALL
                   AND SPURZHEIM.

   Having completed  the anatomy  of the nervous system
as usually described in elementary treatises on the subject,
it  may not be considered superfluous to give briefly the
views of Drs Gall and Spurzheim, relative to the manner
in which the cerebral hemispheres  are formed.  The fol-
lowing appears to be the simplest exposition, and is select-
ed  from  recent writers.  The cerebral hemispheres are
considered by the above anatomists as  resulting from an
expansion of  the  fibres of the medulla ; hence they are
termed primitive or formative fasciculi.   The fibres of the
anterior pyramids may be traced upwards to the margin of
the pons, where they become somewhat constricted.  From
the inner border of  each,  fibres pass  across  the middle
sulcus, and mutually change place, or decussate, those of
the right side passing  to the left and vice versa.  If an in-
cision, a line or two in depth, be made through the pons,
so that one lateral half of it may be turned outwards, the
fibres of the pyramid  will be observed to pass into a quan-
tity of gray substance lodged in the interior of the nodus
encephali.  In this situation the fibres diverge and sepa-
rate,  and are  also  considerably increased : at the upper
margin of the  pons they become continuous with the crus
cerebri.  Here an additional increase  is  derived from their 
NERVOUS SYSTEM.
135
passage through the gray substance lodged in the interior
of the crus, after which they proceed through the inferior
cerebral ganglion (thalamus  nervi optici), and in the next
place through the  superior one (corpus striatum), being
successively increased and rendered still more divergent,
until they finally reach the anterior and middle lobes, where
they are evolved into their inferior, external, and anterior
convolutions.  The corpus  olivare  contains  within  itself
a small ganglion ; its fibres pass, without any decussation,
into the gray substance  lodged in  the cerebral  protuber-
ance, where, like the pyramids, they receive additions, after
which they pass into the crus cerebri, of which  they form
the  posterior and  inner part.  Continuing  their ascent,
they pass through the optic thalamus, and thence into the
corpus striatum, receiving additions  as they radiate through
each, and  finally, are continued upwards into the convolu-
 tions at the summit of the hemisphere, and backwards into
 those of  the posterior lobe.  Previously  to  entering the
 optic thalamus, some fibres of the corpus olivare  have been
 observed to turn inwards, so as  to  give to the  tubercula
 quadrigemina their  medullary investment, and also to unite
 with  those  of  the  opposite side,  to form  the  valve  of
 Vieussens.  The diverging fibres thus traced up through
 their successive steps of increase,  terminate  in the gray
 substance of the convolutions; but another order of fibres
 may be observed quite  distinct from these  and taking a
 different direction.   These are called the converging fibres,
 as they commence at the  peripheral terminations of the
 preceding set, and  pass  from without inwards to the mid-
 dle line, so as to connect the lateral parts, and bring them
 into relation  with one another : on  which  account they are
 called commissures.   The anterior and  posterior commis-
 sures are formed in this way, as is also the corpus callosum;
 though the  greater number of the  fibres which compose
 the latter are transverse,  those towards  its extremities  are 
136
NERVOUS SYSTEM.
oblique.   This is owing to the manner in which the con-
verging fibres of the anterior lobe  are  constrained to pass
from before backwards, and those of the posterior lobe
from behind forwards, in order to gain the corresponding
borders of the corpus  callosum.   By this arrangement a
greater number of fibres are collected to its  extremities,
which renders them thicker (particularly the posterior one)
than any  other part of its extent.   Some  of the  inferior
fibres thus traced from  without inwards, instead of uniting
with the corresponding set along the middle  line, become
reflected downwards from  the under surface of the corpus
callosum  to the  fornix, the fibres of which are stretched
from behind forwards in such a way, that whilst its body is
in a manner unattached, the extremities are identified with
the parts just referred to.
  The formative fibres of  the cerebellum are  derived from
the posterior  pyramids, or corpora restiformia : they pass
upwards and outwards, and  soon  meet the corpus rhom-
boideum,  which is considered as  the ganglion of the cere-
bellum : the fibres are supposed to proceed  through the
gray substance of which it is composed, though it is diffi-
cult  to demonstrate the fact; after which they pass out-
wards, diverging  into  the lobes of the cerebellum.  The
converging fibres, by their union, form the crura cerebelli,
and the fibres of the crus, expanding as they pass down-
wards  and inwards, constitute by their junction the pons
Varolii, which brings  the  lateral  lobes of the cerebellum
into relation, and forms their commissure.  The processus
a cerebello ad testes bring the lobes of the cerebellum into
intimate connexion with the cerebral hemispheres. 
ART.   VIII.
                      CHAP. I.


          PARTICULAR ORGANS OF SENSATION.

            THE EYE AND ITS APPENDAGES.

  The eye and its appendages consist of the globe of the
eye, the eyebrow, the eyelids,  the  ciliae, the Meibomian,
and the lachrymal glands.


                      EYEBROWS.

  The eyebrows are covered with short stiff hairs, gene-
rally of the same color  as  the hair  of the head.  The
skin  in which the bulbs of  the hair  are  implanted, is
placed upon a thick layer of adipose cellular  tissue.  The
frontal, the corrugator supercilii, and the orbicularis palpe-
brarum  muscles move them in the various expressions of
the face.
  The projection of the  eyebrow guards the eye against
external violence ; the hairs, on  account of their oblique
direction,  and  the oily matter with which they are covered,
prevent the perspiration from flowing towards, or irritating
  VOL. II.               IS 
 138            ORGANS OF SENSATION.

the eye ; they direct it towards the temple, and the root of
the nose.


                EYELIDS.   (PALPEBRiE.)

   The  eyelids are those movable veils  which cover the
anterior part of the globe of the eye.
   The upper eyelid is possessed of great mobility ; it is
chiefly by it that the  eye is closed, for the motion of the
lower eyelid is very limited.
   The two eyelids are united at their extremities, forming
two angles,  of which the inner is more open  than the
outer.   The  edges of the eyelids  are  supported by fibro-
cartilages, named the tarsal cartilages, which keep the eye-
lids always extended and accommodated to  the  form of
the globe of the eye.
   The posterior edges of the cartilages are so shaped as to
form a triangular groove  for the tears, when the eyelids are
shut, and as the outer angle of the eyelids is higher than
the inner, the tears are directed towards the puncta lachry-
malia, which  are situated at the inner angle.
   The eyelids cover the eye during sleep, and preserve it
from the injurious effects of extraneous  particles  flying
about in the air; they defend it from sudden shocks by an
instantaneous closure;   and by  their  repeated  motions
(nictation)  diffuse the  lachrymal fluid  over  the  surface,
and  preserve it  in that  polished  state which  is necessary
for perfect vision.  The  eyelids also by their  partial clo-
sure, moderate the effects of too brilliant a  light,  by ad-
mitting only so much as will not offend the eye.
   The eyelashes, or cilia, are strong hairs, most commonly
of the same color as  the hair of the head, and are arranged
in double or triple  rows on the edges of the eyelids ; those
of the upper eyelid are longer than those of the lower, and 
ORGANS OF SENSATION.
139
are curved upwards ;  those of the under eyelid  are direct-
ed downwards.
  These hairs  act  as a shade to the eye, moderate the in-
tensity of the light, and prevent dust and other extraneous
substances from falling into the eye.
  The  Meibomian  glands,  or ciliary follicles, are  small
glandular bodies situated  in  grooves, between the  tarsal
cartilages and the tunica conjunctiva ;  they are arranged in
two vertical lines;  these  follicles communicate with each
other, and  those nearest  the edges of the eyelid  open by
minute  orifices behind the ciliae.
   A sebaceous matter exudes through the orifices of these
glands,  and which may be seen in  the form  of minute
cylinders, on pressing the tarsal cartilages.
   The  tunica  conjunctiva, or  tunica adnata, is a very thin
transparent mucous  membrane, which lines the  posterior
surface  of the eyelids, and is continued over the  fore part
of the  globe of the  eye.   It becomes thin and transpa-
rent  on the cornea, so  much  so, that some  anatomists
have  doubted whether it extends over the entire of its sur-
face.
   On the inner angle of the eye the  tunica  conjunctiva
forms a small crescent-shaped  fold, which has some resemb-
lance to the third eyelid of birds, and is therefore named by
some anatomists the  membrana nictitans.*
   The  caruncula lachrymalis,  is  a small  membranous ele-
vation situated  in the inner angle of the eye ; it  is formed
by a  fold of the tunica conjunctiva, in the  substance of
which are  mucous follicles, and the bulbs of some very
minute hairs.
   The  rose color of  this small body indicates the  energy of

  * This loose fold of the  conjunctiva has not the office nor the muscular
apparatus of the nictitating membrane, and is consequently very erroneously
named. 
140
ORGANS OF SENSATION.
the general system, and  its paleness, on the contrary, de-
notes a state of debility and sickness.*


         THE GLOBE OF THE  EYE IN  GENERAL.

  The eye is composed of two distinct portions of a sphere
united to each  other;  the  anterior segment, which  forms
about the fifth part of the globe, has the smallest diameter.
See Fig. 39.

                    1. THE SCLEROTICA.

  The  sclerotica, (cornea  opaca)  is  a strong,  opaque,
fibrous  substance, which preserves  the globular figure of
the eye ; it is an  envelope which defends its more delicate
internal structure, and serves as a point of insertion for
those muscles which move  the  eye.   It forms about four
fifths of the external investment of the eye, extending from
the entrance of the optic nerve to the border of the cornea.
The external surface is in relation with the conjunctiva, the
expansions of the muscles, and the  vessels and nerves of
the orbit.   It has on its internal  face the choroid membrane.
Posteriorly it is pierced by  the  optic  nerve, and this aper-
ture is divided  by a number of septa, so as to constitute  a
cribriform plate through which the pulp of the nerve passes.
Anteriorly it receives the cornea which  is inserted into  it
somewhat like a watch-glass into its case.


                      2. THE CORNEA.

  The cornea (cornea pellucida) forms the anterior trans-

  *A description of the lachrymal apparatus is given in the article on the
organs of secretion. 
ORGANS OF SENSATION.            141
parent  portion of the globe of the eye; it is not perfectly
circular, the transverse diameter being a little longer than
the vertical.   The cornea is encased in an aperture of the
sclerotica, and presents  the appearance of a segment of a
small sphere added to a larger.   Its anterior surface, which
is convex,is in contact with the conjunctiva; the posterior
is concave, and is  lined  by the  membrane of the aqueous
humor.  Its degree of convexity varies  in different  indi-
viduals, and at the different periods of life.
  The cornea  is thicker than  the  sclerotica, and is com-
posed of several distinct  laminae  superimposed on each
other ;  it does not appear to contain either blood-vessels or
nerves.  When  the  eye is removed from its socket, and
compressed between the fingers, a serous fluid exudes from
between the laminae of the cornea.
   Part of the light which reaches the cornea is reflected
from  its finely polished surface, and  thus contributes to the
brilliancy of the eye ; but its principal office is to cause the
rays to converge to the axis of the eye.
                THE  CHOROID  MEMBRANE.

  The choroid, or the second membrane, is of a dark brown
color,  soft,  cellular, and  vascular;  it  is situated on  the
inner  surface of the  sclerotica;  its outer surface is con-
nected to the  sclerotica  by vessels and  nerves ; its inner
surface is merely contiguous to the retina without adhering
to it.
  The choroid  membrane  is chiefly composed of minute
arteries* and veins, united by fine cellular  tissue ; it is so

  * The ciliary arteries are described in Vol. I. p. 370.  The veins have a
peculiar arrangement, being disposed in whirls, and are therefore denomina-
ted vasa vorticosa, and open into the ophthalmic vein. 
142
ORGANS OF  SENSATION.
exceedingly  vascular,  that after  a successful injection  of
its blood  vessels, it assumes a  uniform red  color.   These
vessels  form  two laminae, which  may be  separated from
each  other.   The  inner lamina was  first  successively in-
jected by Ruysch, and his son subsequently named it
tunica Ruyschiana.
  The pigmentum nigrum is a dark brown substance, cov-
ering the outer  and inner surface  of the  choroid mem-
brane ; on the  latter surface this substance is more abun-
dant, and is  in  immediate contact with the  retina.  Its
office is, apparently,  to absorb  the  rays of light immedi-
ately after they have impinged on the  sensible surface of
the retina.*
   Persons  termed Albinoes have no  pigmentum  nigrum,
therefore the iris and pupil appear of a red color, and their
vision is very imperfect, that is, they cannot view  objects
in  a strong  light; even  during the day  time they can
scarcely see sufficiently to go about.


            THE  CILIARY CIRCLE  OR LIGAMENT.

   Towards the margin of the  cornea, the choroid adheres
 firmly to the sclerotica, constituting what is termed the lig-
 amentum ciliare; within,  it has  the  appearance  of folds,
 which are called the ciliary processes; they indent the hya-

   * Mr G. II. Fielding, in  a communication delivered at Oxford, before a
 meeting of the  British Association, stated his opinion, that this substance
 does not at all poesess the properties of a pigment; that its colors are not,
 as it  has been supposed to be, the result of any secreted matter; that it
 consists of layers separable from theRuyschiana: that it possesses elasticity,
 and above all, circulation;  he thinks, therefore, that we are warranted in
 coming to the conclusion, that it is a membrane, and not a pigment.
   To this membrane he has given  the name of membrana versicolor,
 from the great variety of color it has  in  different animals.  He supposes
 that it receives  the impression of images through the transparent retina. 
ORGANS OF SENSATION.
143
loid membrane, where it splits to form  the  Petitian canal.
The intervals of these processes are covered by the pigmen-
tum nigrum.
  These ciliary processes are sixty or seventy in number,
arranged in a radiated manner around the lens, on the fore-
part of the  vitreous humour.  Each extends inwards and
backwards from the  ciliary ligament as  far as the border of
the lens.  The anterior edge of each process is connected
to the ciliary ligament and iris,  the posterior to  the vitre-
ous humour ;  and the internal  is loose, and forms the cir-
cumference of the posterior  chamber of the eye.


                        THE IRIS.

   The iris is a delicate  circular  membrane, floating in the
 aqueous humour, and suspended vertically  behind the cor-
 nea, so as to  divide  the space between  this and the lens
 into two chambers, an  anterior  and posterior; the former
 is the larger of the two.   These  chambers communicate
 through the central aperture in the iris, the pupil.
   The iris  is so named from its being of different colors ;*
 it is a kind of  circular  curtain placed  in the anterior part
 of the eye, to regulate the  quantity of light passing to the
 back part of the eye.
   The outer circumference  is attached to the ciliary circle ;
 its inner circumference forms the limits of the pupil.
    The iris floats in the aqueous humour,  and is of a very
 contractile nature, so  that when  the  eye is exposed to a
 strong light, or when  we look upon a  near object,  the
 diameter of the pupil is diminished ; and vice versa.
    Upon the back part of  the iris  there is a  dark colored

   * The color of the iris in general corresponds with that of the hair, being
 blue or gray where the hair is light, and brown or black where the hair and
 complexion are of a dark color. 
144
ORGANS OF SENSATION.
secretion, resembling the pigmentum nigrum.   This sur-
face is called the uvea.
  The iris is composed of two laminae, intimately united
near the  pupil.  Some anatomists of great merit state that
these laminae are two sets of muscular fibres, the one con-
centric, round the  pupil, composed of circular fibres con-
tracting  the pupil in  the  manner of a  sphincter; the
other radiated, and having by  its muscular  action the
power of contracting the iris, and  consequently enlarging
the pupil.
  The ciliary arteries, which  supply the opposite sides of
the iris, freely unite with each other : and the smaller ves-
sels of the iris form a circle round the pupil.
  The iris  is supplied with nerves by filaments from the
ciliary nerves.
  The motions of the iris are involuntary, and depend on
the quantity of light falling on the retina; for when the
retina loses its sensibility, the iris does not  move, but re-
mains dilated.
  The pupil in the foetus is  closed by a delicate but vascu-
lar membrane, termed  the  membrana  pupillaris, which is
either ruptured at, or a short time previous to birth.


                      THE  RETINA.

  The retina (tunica nervea) is called the third membrane
of the eye; it is a  soft,  thin,  semitransparent, nervous
expansion, extending  from  the  optic  nerve to the crys-
talline lens,  embracing the vitreous body,  and lining the
choroid membrane without adhering to either of these two
parts.
  At the  posterior  part of the  retina, and exactly in the
axis of vision, there is  a circular foramen  surrounded by
a bright yellow border.  This was  discovered by Soem- 
ORGANS OF SENSATION.
145
mering, and is named  the foramen centrale, or more fre-
quently the foramen of Soemmering ;  it is  about one
thirtythird of an inch in  diameter, but its office is not per-
fectly understood.  Blumenbach supposed that  it might
serve as a kind of pupil, through which concentric rays
might  be absorbed  by the choroid, when the  eye was  in
danger by a very strong light.
  The retina  is  divisible into three  layers ;  viz. serous,
nervous and vascular.  The external or serous is extremely
delicate and is  the one  discovered by  Dr Jacob, and is
now known as Jacob's membrane.
  The retina  is  the  seat of vision, therefore  the primary
part of the  eye, to which  all the other parts, within  the
orbit, are subservient; nevertheless, that part of the  retina
which lies over the entrance of the optic nerve is insensi-
ble to light.
  For the  perfect functions of the retina, it requires  the
light within  a certain  degree of intensity : a  very  feeble
light is not felt  by the retina;  too strong a light hurts it,
and renders it for some time unfit for action.
VOL. II.             19 
146
ORGANS OF SENSATION.
Fig. 39.
  Fig. 39.  A diagram of the eye.
  a, the eyelid.
  b, the tunica conjunctiva lining the eyelids, and reflected
over the anterior part of the eye.
  c, c, the cornea.            d, d, the sclerotica.
  e, the aqueous humour.    f the iris.
  g, the crystalline lens.     h, the vitreous humour.
  i, the choroid tunic with its pigmentum nigrum.
  k, the ciliary processes.     I, the retina.
  m, the punctum lachrymale.
  n, the caruncuja lachrymalis.
  o, the central  artery of the retina.
  p, the optic nerve.


                THE  AQ.UEOUS  HUMOUR.

  The aqueous humour is as clear as the purest water, but
its  specific gravity is somewhat greater; it is  about five 
ORGANS OF SENSATION.
147
grains in weight, and consists of water impregnated with
albumen, gelatin, and muriate of soda.
  The aqueous humour is situated between the cornea and
crystalline  lens, and, being confined in this space, forms a
meniscus, which  assists in collecting and transmitting the
rays of light to the inner part of the eye.
  The light only which passes the pupil can be of use in
vision ; that which falls on  the iris  is reflected, returns
through the cornea, and exhibits the color of the iris.
  The  membrane of the aqueous humour is  extremely thin,
and perfectly transparent, lining  all the anterior  chamber
of the eye, but not extending  to the posterior chamber.
The first of these chambers  is about two lines, the latter
about half a line in depth.   This membrane secretes the
aqueous humour  in the  first instance, and reproduces it
when evacuated by accident  or during operations.


                THE CRYSTALLINE LENS.

  The  crystalline lens is a  transparent body placed be-
tween the  aqueous humour and the vitreous body, lying
behind the iris, surrounded by the ciliary processes.  It is
a double convex lens, of which the anterior surface is flat-
ter than the posterior, the diameter of which is four lines,
and its thickness about  two; its axis  corresponds to the
centre of the  pupil.
   The lens appears to be composed of  several distinct
layers, an  exterior, very soft  and  easily removed, and the
interior forming a more solid  nucleus, made up of a great
number of concentric  superimposed  laminae ; and each of
these laminae is composed of very fine fibres, like those of
spun glass.
   If the lens  be dried it may also be divided  into three
segments of a sphere, in the  centre of which there exists a
small transparent globule. 
148
ORGANS OF SENSATION.
   In its chemical composition it differs very little from the
 aqueous humour,  only in having  a larger proportion  of
 gelatin and albumen, and in being free from saline matters.
   The  membrane, or  capsule, of the lens is also perfectly
 pellucid, and adheres very slightly to the lens, so that when
 the capsule is punctured, upon making gentle pressure on
 the eye, the lens starts out.  The  capsule receives a mi-
 nute branch of the central artery of the retina, and  ramifi-
 cations  of the vessels of the ciliary processes.  It encloses
 a small  quantity of fluid which is termed liquor Morgagni.
   The  crystalline lens  is retained in  its  situation  by nu-
 merous  delicate transparent filaments, which pass from the
 ciliary processes to the circumference of the capsule of the
 lens.
   The office of the lens  is not  only to assemble the rays
 of light upon a certain part of the  retina, but  to increase
 the  intensity of the light, which  is directed  towards the
 back of the eye.  It may also be added, that  the light
 which passes  near the circumference of the  crystalline
 lens, is  probably refracted in a different manner from that
 which passes through  the centre; so that  its peculiar
 structure is supposed to have the effect of correcting that
 aberration which is always  produced  by the  sphericity of
 ordinary lenses.


                  THE VITREOUS BODY.

  The vitreous body, or humour,  is  so called from  its  re-
 semblance  to  melted glass: it is  a perfectly transparent
 tremulous mass, occupying the globe  of the eye, from the
entrance of the  optic nerve to the surface of the crystal-
line  lens, or about  the  posterior  two-thirds of the  globe.
It is invested, in nearly its whole  extent, by the retina, but
to which it is not adherent; so that its connection with the 
ORGANS OF SENSATION.
149
Fig. 40.
other parts of the eye, is  merely by the  central artery of
the optic nerve, which passes through it, to the posterior
part of the capsule  of the lens.
   The vitreous  body is composed  of a fluid or humour
contained in cells, formed of the hyaloid membrane.
   The chemical  properties of the fluid of the vitreous body
are similar to those  of the aqueous humour.
   The hyaloid membrane, which contains the  vitreous  hu-
mour,  is excessively thin and transparent, and constitutes
an innumerable  mass of cellules which communicate with
each other, so that  by making a puncture  in  the  hyaloid
membrane the whole humour will escape.
                      Fig. 40,  the  refracting  media  of
                     the eye.
                       a, the aqueous humour.
                       b, the crystalline  lens.
                       c, the vitreous humour.
                       The Petition canal  is named after
                     Petit, who discovered it.   This ca-
                     nal, Fig. 41, is formed merely by, b,
the  laminae of the  vitreous  humour which passes before
and behind, a, the  lens, and  becomes identified with its
                    capsule; thus, leaving  at, c, its mar-
                    gin,  a  somewhat   triangular  space,
                    which may  be  demonstrated by infla-
                    tion : although, strictly  speaking, it
                    does not exist in its  natural state, for
the laminae are in perfect contact, the canal being formed
artificially, by blowing air between the  posterior  surface of
the  capsule of  the lens, and the  hyaloid  membrane  on
which the lens rests.
   The anterior lamina of the canal  of Petit presents  ra-
diated striae and  contractions, corresponding to the ciliary
process, forming a curious and beautiful appearance.
   The vitreous body possesses a less refractive power than
Fig. 41.
 
150
ORGANS OF SENSATION.
the crystalline, therefore, after  the  rays  are  collected by
the latter, the vitreous body continues their  convergence,
increases the field of vision, and  assists  in  bringing  the
rays to an accurate focus on the retina.
                      CHAP. II.


            THE  EAR AND ITS APPENDAGES.

  There are a number of organs in the apparatus of hear-
ing, which, by their physical properties and functions, con-
cur in collecting and transmitting sounds, and  there is a
nerve for the purpose of receiving and conveying the im-
pressions of sonorous vibrations to the sensorium.
  The organ of hearing is divisible into three  parts, viz.
the external ear, or auricula, the tympanum, and the laby-
rinth.
                  THE  EXTERNAL EAR.

  The external ear comprehends the pinna or auricle, and
the meatus auditorius externus.
  The auricle consists of the pavilion or ala, which is by
much the greater part of it, and the lobus which is the most
dependent portion.
  The exterior of the ear  presents the following  remark-
able prominences and depressions, viz: — 
ORGANS OF SENSATION.
151
                      1. h, h, Fig. 42, the helix, a rim of
                    nearly a semicircular shape surround-
                    ing its upper edge ; and  continued
                    to, I, the lobe of the ear.
                      2. a, the anti-helix, an inner semi-
                    circular eminence,  which is situated
                    within the former,  and is formed su-
                    periorly  of  two  ridges uniting to-
                    gether below —
                      s, the scapha, the depression which
separates the two roots of the anti-helix.
  3. t,  the  tragus, a small eminence  situated over the
meatus externus, and connected to the under and fore part
of the helix.
  4. a,  t, the  anti-tragus,  is  another  eminence situated
behind,  nearly opposite  to  the tragus, and at the inferior
extremity of the anti-helix.
  5. c, the  concha, is a  large  cavity under the  anti-helix,
and leading to the meatus auditorius.
  6. I, the lobe of the ear, is the inferior soft part of the
ear, and is composed of cellular tissue with a small quan-
tity of fat.   This is the part which it has been customary,
in many countries, to perforate for the purpose of suspend-
ing rings and other ornaments.
  The office of the auricle of  the  external ear is to collect
the sonorous  radiations, and to direct them towards the
auditory passage. 
152
ORGANS OF SENSATION.
             FIBRO-CARTILAGE OF THE EAR.

  The  fibro-cartilage  of the  ear,
Fig. 43, constitutes its basis, deter-
mining  the form of that part:  in its
consistence and elasticity, it is analo-
gous to those of the nose.
  All the eminences  and depres-
sions just described are formed by
it, as may be seen  in  the annexed
figure — h, h,  the cartilage  of the
helix;  a, the anti-helix ; s, the sca-
pha ; t, the  tragus;  a, t, the  anti-tragus ;  c, the  concha.
These fibro-cartilages are covered by a dermal layer, having
a great number  of  sebaceous follicles disposed  through
it.  The inner  surface of, t, the tragus is  furnished  with
hairs, which appear destined to  prevent  small  particles,
which float in the atmosphere, from entering the auditory
passage.
  There are ligaments which serve to fix the fibro-cartilage
to the  side of the head, called the superior, the anterior,
and the posterior ligaments; they are more cellular than
fibrous, and are  intermingled with the muscular fibres of
the auricle.
  The principal muscles of  the ear have been  already de-
scribed, and those that remain, which belong to the carti-
lage, are of small size ; one or more of them are sometimes
absent; at other times, Cloquet states, he  could meet with
none ; indeed,  so insignificant are  these muscles that I am
not aware that, in  any person, they possess  the power of
moving the part  they are  attached to.   The following,
however, is  an  enumeration  of them.
  1. The transversus auris, extending from  the convexity
 
ORGANS OF SENSATION.
153
of the concha, to the prominence which the groove of the
helix forms posteriorly.
   2. The tragicus is of a triangular form, and almost en-
tirely covers the outer surface of the tragus.
   3. The anti-tragicus  occupies the interval which sepa-
rates the anti-tragus from the anti-helix.
   4. The helicis major  covers, for a  few lines, the  helix
above the tragus.
   5. The helicis minor is situated beneath and behind the
preceding, on the prominence  of the helix.
   The muscles of the external ear, no doubt, are calcula-
ted to expand the different hollows of which the surface is
formed.   Among savage tribes  the  ear is prominent and
movable, like the ears  of animals ; their hearing is more
acute than  that of civilized nations ;  and it  is  probable,
that the motion of the external ear assists them in discrim-
inating the nature of different sounds.


                  the auditory canal.

   This canal extends from the concha of the ear  to the
 membrane of the tympanum ;  it is composed of bone and
 cartilage, lined by a very fine skin, and defended by a pe-
 culiar acrid  sebaceous substance, the  cerumen, or the wax,
 furnished  by  the cerumenous glands; this  canal  is also
 fenced  by a number of hairs.  It takes a direction first
 forwards, upwards, and inwards, then downwards and  in-
 wards.  It is therefore curved, or concave downwards, and
 about an inch in length.
VOL. II.
20 
154
ORGANS OF SENSATION.
                  the internal ear.

  The internal ear consists of the cavity of the tympanum,
the vestibule, the cochlea, and  the parts communicating
with them.
  The tympanum  is a narrow chamber  which opens into
the posterior fauces through the Eustachian  tube, and is
continued backwards into the cells of the mastoid process
of the temporal bone.
  The Eustachian tube descends  obliquely forwards and
inwards, and  terminates in a trumpet-shaped mouth, be-
hind the posterior nares, on a level with the inferior spongy
bone.  It is small and osseous posteriorly ; anteriorly it is
large, and  formed externally of membrane, and  internally
of  fibro-cartilage.  It is lined by  mucous  membrane.
Through this tube, the air can  pass  from the fauces into
the tympanum, to support the  latter on its internal sur-
face.
   The membrana  tympani is extended  over  the  circular
opening, at the bottom of the external meatus.
   The foramen ovale,  or fenestra ovalis, is an aperture of a
shape which the name implies ;  it forms a communication
between  the tympanum and vestibule.
   The foramen rotundum, or fenestra  rotunda,  is  of smaller
dimensions than the preceding foramen, and  forms a com-
munication between the inner scala of the cochlea and the
tympanum.
   The promontorium is an eminence  formed by the outer
side of the vestibule, and by the corresponding scala of the
cochlea. 
ORGANS OF SENSATION.             155
THE BONES  CONTAINED  IN  THE  CAVITY  OF THE TYMPA-
            NUM, OR THE  OSSICULA AUDITUS.

  A series of very small  bones* extends  from the mem-
brana tympani to the fenestra ovalis and consequently to
the labyrinth.   These  convey to  the deepest  parts of the
internal ear, the changes which supervene in the membrane
of the tympanum.   They are named the malleus, the incus,
the os orbiculare, and the stapes, and there are muscles ap-
propriated to put them into motion.
     Fig. 44.        The malleus, Fig. 44, which is described
                as having a head, a neck, a handle, and a
                process.
                  The handle of the malleus is attached
                to the membrana tympani, being situated
 between the layers of it.

                  The incus, Fig. 45,  consists of a  body
                and two crura.   It is  articulated to the
                malleus,  and  is  fixed by  a  ligament to
                 the sides of the mastoid  cells.

                   The os orbiculare, Fig. 46, is articulated
                 to  the long process of  the incus.

                   The stapes,  Fig.  47, is distinguished
                 into a head, crura, and base.  This  bone
                 is placed horizontally, with its base resting
                 against the  fenestra ovalis, and  its  head
 articulated  with the os orbiculare.
    There are three muscles by which this series of bones is
 moved: —
   » The annexed figures of the bones, as well as  those which follow with
 the muscles attached to them, are magnified to twice the natural size.
Fig. 45.
Fig. 46.
Fig. 47. 
156
ORGANS OF SENSATION.
  1. The laxator tympani, Fig. 48,  a, is
attached to the upper part of the edge of
the tympanum, near to the part  to which
the membrane of the tympanum adheres,
and is extended to the handle of the  mal-
leus.
  2. The tensor tympani, c, is attached to
the upper part of the Eustachian tube, and to the handle
of the malleus below its process.
  3. The extensor mallei,  b, or  the musculus processus mi-
noris of Valsalva, is figured by Sir C. Bell, but  it is not
acknowledged by Cloquet and some other anatomists to
be  of the nature of  a muscle.
  4. The  stapedius, Fig.  49,  a,  is the
smallest muscle, and is  attached near the
mastoid cells, and into the head of, b, the
stapes.
THE LABYRINTH.  Fig. 50.
  * To obtain the exact form of the exterior of these parts, we may pour
melted lead into the external meatus of the temporal bone, the bone may
be afterwards easily removed, and we have a metallic cast of these delicate
parts.
 
ORGANS OF SENSATION.
157
  The labyrinth, so called from its  sinuosities and wind-
ings, is situated between  the tympanum and the meatus
auditorius internus ;  it is formed of several cavities, which
are designated by the names  of, a, the  vestibule, 6, the
cochlea, and, c, c, c,  the semicircular canals.
  The vestibule, named from  its forming an entry to the
cochlea and semicircular canals, is a cavity of an irregular
form, containing several  apertures,  which  communicate
with the neighboring parts, which we must again notice,
viz : —
   1st. d, the fenestra ovalis, or foramen ovale, which com-
municates with the tympanum, and  upon which  is placed
the base of the stapes.   2d. Superiorly, the two anterior
orifices of the superior vertical and horizontal semicircular
canals.   3d.  Posteriorly,  the two separate openings of the
semicircular canals, and  one opening common to the two
vertical  canals.  4th.  On the inner side  is a number of
small perforations for the  transmission of blood-vessels and
branches of the auditory nerve.  5th. Near the common
orifice of the  vertical  canals we find the  opening of the
aqueduct of  the  vestibulum,  extremely  small, extending
from this  cavity to  the  posterior surface  of the petrous
portion of the temporal bone.


                     THE COCHLEA.

   The cochlea, Fig.  51, is situated on the inner side of the
vestibulum, in the anterior  part of the  petrous portion of
 the temporal bone :  it is an osseous, shell-like cavity, form-
 ed  by  two  conical  canals, twisted in a spiral  direction.
 See Fig. 50, b. 
158
ORGANS OF SENSATION.
Fig. 51.
   Fig. 51, represents a  section of  that  part of  the pe-
trous portion  of the temporal  bone which contains the
cochlea.
   1st. b, b, the modiolus, an  osseous conical pillar in the
centre of the cochlea, terminating in a small cavity, c, call-
ed the infundibulum.
   2d.  a, a, the lamina spiralis, formed  round,  b, b, the
modiolus, takes two turns and a half, and terminates by a
hook at c, in the infundibulum.
  3d.  The spiral septum, dividing the cavity of the cochlea
into two smaller ones.
  4th. The gyri, which are  the spiral cavities  formed by
the septum.
  5th. The aqueduct, an extremely  narrow passage open-
ing, superiorly, into the cavity of the tympanum, near the
foramen rotundum ; inferiorly, in the posterior petrous por-
tion of the temporal bone. 
ORGANS OF SENSATION.
159
              THE SEMICIRCULAR CANALS.

  The form of the  three canals, Fig. 50, c, c, c, is indicated
by the name;  they are situated  in  the substance of the
petrous portion of  the temporal bone, and open  into the
vestibulum by  five  orifices.
  The cavities of the internal ear are lined by a very deli-
cate membrane; and each of the  semicircular canals con-
tains  a membranous tube, opening  into  a common sac,
which occupies  a  portion of,  d, the vestibulum, and con-
tains a small quantity of a peculiar fluid.  The vestibulum
also is lined by another membranous sac, filled with a
limpid fluid, called the liquor of Cotunnius ; it sends a
prolongation of  its membrane  into  the aqueduct of the
vestibulum, and this prolongation terminates in a small
cul-de-sac under the dura mater.
   The membrane of  the  vestibule appears to  introduce
itself into the  cochlea by the orifice of the external  scala,
lines all its cavities, is continued into the aqueduct  of the
cochlea, and  terminates by a  cul-de-sac under  the dura
mater.


          THE ACOUSTIC, OR  AUDITORY NERVE.

   The acoustic nerve  proceeds  parallel to the facial, so
long as it is contained  within  the skull; it then introduces
itself with it into  the internal  auditory canal, and divides
into two branches: — 
160
ORGANS OF SENSATION.
Fig. 52.
   1.  The branch of the cochlea, Fig. 52,* a, on arriving at
the base of the cochlea, divides into a great number of very
slender filaments, which enter into apertures of the cochlea,
and spread out their  ramifications on, b, b, the lamina spi-
ralis in a very dense net-work.
   2.  The branch of the vestibule and semicircular  canals,
c,  d, g, is at first united to the preceding, but afterwards
separates from it, and  forms an enlargement, from which
proceed filaments which are distributed to, f the vestibule,
and to, A, h, h, the semicircular canals.   At the  entrance
of the  posterior vertical canal, we observe, at  g, the in-
creased size of the nerve in the ampulla, or  enlargement of
the extremities of the canals.
                MECHANISM OF HEARING.

  The external ear collects the sonorous  radiations, and
directs them towards the auditory passage ;  and this tube
transmits  sound in  the same manner as any other canal,
partly  by the  air  it contains, and  partly by its parietes.
* The three last figures are considerably enlarged views. 
ORGANS OF SENSATION.
161
until it arrives  at the membrane of the tympanum; this
membrane  vibrates under the influence of the sonorous
undulations which  the meatus conducts to it.   The series
of little bones, next, has  a peculiar action upon the mem-
brane of the fenestra  ovalis, so that the  liquor of Cotun-
nius receives  vibrations which  are  impressed on  the
acoustic nerve.
  The  gyri of the cochlea receive  the vibrations princi-
pally by the membranes  of the fenestra ovalis ;  the vesti-
bule, by the  series of bones:  the  semicircular  canals, by
the sides of the tympanum : but the  assistance which is
given to hearing by the several parts of the internal ear is
totally  unknown.
  It is, however, certain  that impressions are received and
transmitted  to  the brain by the  auditory nerve; and the
brain perceives  them with more or less facility and  exact-
ness in different individuals.
VOL. II.
21 
162
ORGANS OF SENSATION.
Fig. 53.
  Fig. 53, exhibits  the  organ of hearing, of the  natural
size.
  a, the external ear.
  b, the tympanum, exposed by opening the vestibule.
  c, the cochlea.
  d, the three semicircular canals laid open.
  e, the osseous part of the Eustachian tube.
  /, the membranous extremity of the Eustachian tube,
opening into the fauces.
  g, the petrous portion of the temporal bone.
  h, the meatus auditorius externus, on which is seen the
cerumenous glands.
  1, the stapes ; 2, the os orbiculare ; 3, the incus ; 4, the
malleus; a series of  bones which transmits the  vibrations
of the tympanum. 
ORGANS OF SENSATION.
163
CHAP. III.
THE NOSE, OR ORGAN OF SMELL.
Fig. 54.
  The external part of the organ of smelling, or the nose,
properly so  called, is composed superiorly of bones, and
inferiorly of cartilages; it  has a  partial  covering  from
muscles,  and  a general one from  the  common integu-
ments.
                  The  osseous  part of  the  nose  has
                already been described ;  the  ossa  nasi,
                Fig. 54, a, forms the bridge.
                  The fore part  of the nose contains
                five cartilages,  of a regular figure, and
                some smaller pieces which  are more  ir-
                regular.
                  The middle cartilage, c,  is  the  most
                considerable, and  supports  the rest;  it
                constitutes the cartilaginous  part  of the
septum narium, and is united to  the anterior edge of the
nasal lamella of the  ethmoid bone, to the anterior edge of
the vomer, and to the  fore part of the  spinous  process of
the superior maxillary bones.
  b, the two superior  lateral cartilages are placed  some-
what anteriorly, so that by their union they form the centre
of  the  nose ;  d, the  two  inferior,  laterally and  at the
extremity, so as to form the tip of the  nose;  and, e, the
alae nasi.
  Between the anterior and posterior  cartilages we find
additional cartilages, the number, size, and figure, varying
in different  individuals.
 
164
ORGANS OF SENSATION.
  The elasticity of the cartilages contributes to the defence
of the nose against external injuries.
  The muscles which move the cartilages of the nose have
been described.
  The internal cavities of the nose extend upwards to the
cribriform plate of the  ethmoid, and to the body  of the
sphenoid bone.  At the  inner  side, they are bounded by
the septum narium, and on the outer side, by the turbina-
ted bones, which, as we have seen in the skeleton, project
considerably into the nasal cavities, and increase the sur-
face of the membrane of the organ of smell.
  The floor of the nostrils passes directly backwards in a
horizontal direction to the throat.
  The nose is lined by a thick and spongy  mucous mem-
brane, termed, the membrana pituitaria of  Schneider, or
the Schneiderian membrane; which secretes a mucus that
defends the nerves from the current of air which is respired;
by this mean they  are preserved moist, and  rendered fit for
the impression of effluvia.  This membrane adheres to the
periosteum, to the sinuses, to   the lachrymal sacs, Eusta-
chian tubes, pharynx, and palate, and  is intended to stop
any foreign body  which may be mixed with the  air.  The
pituitary membrane is extremely vascular, and over the
whole of it is distributed filaments of, —

                         Fig. 55.
 
ORGANS OF SENSATION.
165
  b, Fig.  55, the fifth pair of  nerves, which  endue  the
membrane with ordinary sensibility. The distribution of the
first nerve, a, d, the olfactory, is more limited.  The latter
perforates the  cribriform plate of the ethmoid  bone, and
spreads in numerous filaments over the  septum narium,
and surface of the upper  turbinated bones ; this nerve is
the essential organ of smell, and conveys a  perception of
odors to the sensorium.
  The  maxillary  and sphenoid  sinuses, and  the ethmoid
cells, open into the nasal  cavity, and are lined by a con-
tinuation of the mucous membrane just described.


                 MECHANISM OF SMELL.

   A great many substances in nature emit certain particles
of  extreme tenuity, which are carried by the  air, often to a
great distance ; these particles constitute odors ; the organ
of  smelling is  destined to perceive and  appreciate them ;
thus an important relation is established  between animals
and other bodies.  The mechanism by which we smell, is
extremely simple : it is only necessary that the odoriferous
particles should be detained upon the pituitary membrane,
particularly in the parts where  it  receives the  filaments of
the olfactory nerve.   The nose also contributes to the gen-
eral purposes  of respiration  and the  modulation of the
voice, and receives  the superabundant fluid from  the ex-
ternal surface of  the eyes. 
166
ORGANS OF SENSATION
                      CHAP.  IV.

          THE TONGUE, OR ORGAN  OF TASTE.

  The tongue is a muscular organ,  possessing great mo-
bility, and is the principal organ of taste; but this  is not
its only use, for it is the chief instrument of speech, and
contributes to the acts of sucking, mastication, and deglu-
tition.
  The muscular portion of the tongue  forms the greater
part of its substance, and is composed of the fibres of the
stylo-glossi, the  hyo-glossi, and the  genio-glossi muscles,
which have already been  described :  beneath, and on each
side also, are  two parallel  fasciculi  of fibres,  which are
named the lingual muscles.  All  these  muscles, however,
have their fibres  interwoven in a most inextricable manner.
In the  upper part of the tongue, there are interposed small
adipose globules.
  At  the centre of this fleshy tissue there is a fibro-carti-
laginous  septum, which gives attachment to the muscular
fibres.
  The mucous membrane, which  lines the whole interior
of the  mouth, passes to the under surface of the tongue,
forming in the centre  a fold which is named the franum
lingua.  The same membrane then extends on each side,
beneath the tongue, ascends upon its edges, passes over its
upper surface, and forms  three folds near the epiglottis.
  On the upper surface of the tongue  the  mucous mem-
brane presents a very  different appearance to that  on its
inferior surface; there it  assumes  a distinct  epidermis,
under which is a tissue formed of numberless vessels and
nerves, which  constitute  a  net-work, surrounding the pa- 
ORGANS OF SENSATION
167
pillae and mucous follicles, and which give  to the tongue
the red color peculiar to it.  The upper surface is render-
ed rough  and uneven by the existence of  a  very  great
number of projections differing in  their form.  These are
the papilla, which may be distinguished into  three kinds.
   1. The lenticular papilla vary in number  from nine to
fifteen ; they are observed only at the posterior part of the
tongue, arranged  in oblique  lines, like the  letter  v, and
meeting at a considerable depression, termed the foramen
ccecum of Morgagni, by whom it was first described.
   The lenticular papillae  are generally spherical  or  oval ;
they are not like the other papillae, organs of  taste, but are
simply mucous follicles, which open  upon the tongue by
very small orifices.
                2. The  fungiform papilla,  Fig. 56, of a
              whitish appearance, are disseminated irregu-
              larly near the  edges of the tongue;  they
              present a rounded flattened head, supported
              by a narrow pedicle.
     Fig. 57.       3. The conical papilla, Fig. 57, or papilla
              media.—These are  by much the most nu-
              merous, and occupy almost the whole  upper
              surface of the tongue, becoming gradually
shorter at the sides, and longer and  more abundant at the
apex, where the sensation of taste is most acute.
   These  papillae resemble  small  cones,  attached  to the
tongue by their  base, and  free at their summit; they are
placed close to each other, but at many parts leave irregu-
lar intervals in the form of clefts.
     Fi  5g       The filiform papilla, Fig. 58, are observed
     « ** n   at the  edges of the tongue ; they assume a
     WvW    shred-like appearance, and  are of a similar
              fabric to the last.
 
168
ORGANS OF SENSATION.
        Fig. 59.
d
  The nerves of the tongue, as we may observe in the an-
nexed figure, are very abundant, and are furnished by, b, e,
the inferior maxillary ;  c, the  glosso-pharyngeal; and, a,
the hypoglossal nerves.
  Behind the fringes formed under the tongue, we perceive
an  amygdaloid granular mass, amply  supplied  by blood-
vessels, and by filaments of the lingual nerve.


                        TASTE.

  Although the tongue is  the principal organ of  taste,
the lips,  the internal surface of  the cheeks, the palate,
and even the teeth are sensible to the  impression of sapid
bodies.
  To excite a  sensation  of taste, a substance must be in a
liquid state: to promote this object, when a  solid is placed 
ORGANS OF SENSATION.
169
in the mouth, the saliva  is observed to flow abundantly,
and its sapid qualities are  perceived in proportion as it dis-
solves ;  and there are many substances which we cannot
perfectly taste unless their fumes ascend into the cavity of
the nostrils :  indeed,  sensations of taste  are not perfect
until the mouth is closed,  and  the tongue  pressed against
the palate, by which means the sapid body is brought more
immediately into  contact  with the surface of the tongue,
and perhaps forced into the nervous membrane, at the same
time that the fumes are driven through the posterior fauces
into the nasal cavities.
  The choice of food entirely depends on the taste ; joined
to smell, it enables us to  distinguish between substances
which are hurtful, and those that are nutritious.
CHAP. V.
                    THE  SKIN.

  The skin is a dense  membrane of variable thickness,
according to the part which it covers ; it is very flexible,
and  envelopes the  whole body : at the circumference of
the apertures,  as at the nose, the mouth, etc. it is continu-
ous with  the mucous membrane which lines those cavities.
  The skin is  composed of three very distinct  layers ; the
dermis, or chorion, the rete mucosum, and the epidermis, or
cuticle.
  vol. u.              22 
170
ORGANS OF SENSATION.
  The external surface of the  skin is  covered by a vast
number of  small  projections, rasembling  papillae, and  it
is  furrowed by a multitude of wrinkles,  some of which
are occasioned  by the action of muscles,  as in the  fore-
head, the hand, and the sole of the foot; others are produ-
ced by the flexure of joints, or  by  the rows of papillae, as
we observe at the extremities of the fingers.
  This surface  of the skin presents a multitude of pores,
very visible by  the aid  of a microscope ;  it has been ques-
tioned whether these pores are the terminations of exha-
lent vessels, out of which the  drops of sweat  issue ; but
they may be considered as perforations made by the excre-
tory ducts of sebaceous follicles, or by the  hairs.


                      1. THE dermis.

  The dermis is the thickest layer of the skin, and is form-
ed of fibres, interwoven in an inextricable manner, and is
so plentifully furnished with blood-vessels and nerves, that
the smallest puncture  cannot be made, in any part of it,
without occasioning pain and a discharge of blood.
  The dermis is  strong and elastic, and forms the most
substantial part of the skin ; indeed, it is that part, in quad-
rupeds, of which leather is made.
  The outer part is very  compact, the  inner  more loose,
and it gradually degenerates into the  common  cellular
tissue.
  The dermis is covered in all its regions with more or less
distinct prominences, and  irregular  depressions, which ap-
pear through the epidermis.  The asperities are named the
papillae, and  are divided  by a series of small depressions,
to the number of four or  five in  the  extent  of a  line.
On the points of the toes, and  on the tips of the  fingers,
the papillae generally take a somewhat  spiral and parallel
direction. 
ORGANS OF SENSATION.
171
  Blood-vessels twine in the subcutaneous cellular  tissue,
and project  an infinitude of small  branches, which pene-
trate into  the remotest areolae of the  dermis,  unite in a
variety of ways, cross the external surface, and  finally give
rise to that capillary net, which I shall describe in speaking
of the rete mucosum.
  The nerves are  distributed nearly in the same order as
the blood-vessels ;  there is  a subcutaneous stratum of  the
nervous system  from which  pass  all  the filaments which
penetrate  the dermis.   These filaments  frequently unite
and  insinuate themselves into  the  internal  areolae,  and
undoubtedly terminate in giving origin  to the papillae.   In
the hand, and at the points of the fingers, where  the papillae
are remarkably conspicuous, there is a  larger proportion of
subcutaneous nerves than in  any other part of the  body;
and it cannot  be  doubted  that  the soles of the feet,  the
palms of the hands, and the tips of the fingers, are gifted
with much more sensibility than any other parts.


                  2. THE RETE MUCOSUM.

  This  tissue lies immediately  under  the dermis,  and is
the chief cause of  that variety of color which characterises
the natives of different climates, and different people of the
same climate ; being white, or rather of a light gray in  the
European, brown in the Asiatic, and black in the African.
And, on account of the thinness and  transparency of  the
dermis, the color of the rete mucosum  appears through it.
  The rete mucosum then may be conceived as a general
capillary system, enveloping  the cutaneous  organ,  and
forming, in common with the papillae, a stratum interposed
between the dermis and  the  epidermis.   In different sub-
jects it has a different  hue, forming  the complexion of the
individual, and there is every intermediate  color from  the 
172
ORGANS OF SENSATION.
swarthy hue of the negro, to the fairest  skin of the Euro-
pean.  Hence, the complexion  depends on the substance
which exists in the very minute  vessels of the skin.
   It is likewise the cause of the  difference of color in dif-
ferent parts of the body of the same person, and is compo-
sed, according to  Gaultier, of four  distinct  layers; the
first counting from within  outwards, is formed of blood-
vessels arranged like granulations, on the asperities of the
dermis ;  the second is whitish, and  applied upon the for-
mer,  in  the  irregularities  of the  dermis, and there are
numerous prolongations of this layer which penetrate into
the substance  of the dermis; the third layer is composed
of minute convex bodies, containing the  coloring matter of
the skin ; the  fourth layer  is white, of extreme  tenuity,
perforated by the hairs, and adherent to the epidermis.


                    3. THE EPIDERMIS.

   The epidermis, or cuticle, is the  most superficial  layer,
and is separated from the  dermis  by the  rete mucosum.
It presents all the wrinkles and furrows  which have been
mentioned in the  description of the outer surface of the
dermis;  it is thin,  and transparent, and  formed of numer-
ous scales in close apposition with one another.  The inner
surface is very firmly attached to the dermis, on removing
it  by maceration, we observe a  multiplicity of* small pro-
longations, which appear to be nothing more than processes
which line the passages through which hairs  grow and the
sebaceous follicles  open.
   A great number of sebaceous follicles are seated under the
skin,  and open by small ducts on its surface ;  Mr Cheva-
lier* counted one hundred and forty in the space of a quar-

  * Lectures on the General Structure of the Human Body, delivered at the
Royal College of  Surgeons.—p. 186. 
ORGANS OF SENSATION.
173
ter  of an inch, which will make one hundred and  twenty
millions on the surface of the whole body.   These follicles,
or glands, secrete an oily fluid which serves to lubricate the
skin, and defend it from the inclemency  of the weather, or
from the effects of friction.
  Immense multitudes of perforations have been supposed
to exist in  the epidermis, for the purpose of allowing the
perspirable matter to escape from the body.   But are there
any in reality ?  A microscope of high powers will  not de-
tect them ; we can only discern those  apertures which be-
long to the hairs, and the sebaceous follicles.  The serum,
produced by a blister, will not exude  from within, nor will
water or other fluids penetrate from without.   How then
is the office of perspiration carried on through the cuticle ?
Instead of porosity, this appearance results from an infinite
number of velaminae, regularly arranged, of exquisite tenu-
ity, presenting a follicular appearance, and separated from
each other by filaments crossing in a  thousand different
directions.   The terminal vessels of the  cutaneous  appara-
tus transmit  the perspiration through  this tissue,  without
the inconvenience of perforated  pores.  Perspiration then
is a secretion  produced by the action of the sudatory ves-
sels, and not  an exudation,  and the skin constitutes one
wide  and  diffused perspiratory gland ; a subtile  fluid  is
separated from the circulation by it,  from the  invisible
vapor of perfect health and ease, to the profuse and colli-
quative sweat of a languishing hectic.   The  skin, there-
fore, seems the natural and appropriate  recipient of the
capillary vessels of the cutaneous secretion, which it trans-
mits  through that exquisitely fine  gauze of  the epidermis.
Perspiration  liberates  from  the blood  superfluous animal
gas, and water; and by its copious evaporation in summer,
and its partial suppression in winter, it regulates the tem-
perature of our bodies, and thus the skin acts as the safety-
valve of life and health. 
174
ORGANS OF SENSATION.
  Exhalents, absorbent vessels,  and hairs pass through
the epidermis, but no blood-vessels have been traced in it,
either  by the  eye or by the assistance of glasses:  it pos-
sesses, therefore, none of the properties of life : it wears
away and is renewed  continually, and its thickness lessens
or augments, as  it is  needed ;  it becomes  hard and thick
on  the hands  of the laborer,  and soft  and delicate on
the hands of those who are  occupied in lighter employ-
ments.
                 the  sense of touch.

  This  is the fifth sense, and  must be  included in  the
description of the skin.   None of the  vertebrata inferior
to man are endowed with the special organ of touch; and
although the general surface is in  most animals  an organ
of sense, the distinct faculty of touch is entirely wanting,
or exists in a very modified degree.  It is in the sense of
touch, says Cuvier, that we excel every other animal, why?
Because this sense is quite different from the others ; this
is consequent to them, and rectifies their errors :  we feel,
because we have seen,  heard, tasted, or  smelt the objects.
Touch is voluntary, and reflection is necessary to  exercise
it, while the other  four require none.   Light, sound, etc.
may strike their respective organs unnoticed, but we touch
nothing without a preliminary act of the intellectual func-
tions.
  Sensibility to  cold  and various  stimuli does  not prove
that the lower grades of animals have the sense of touch ;
our own species inherits this common sensibility, which we
maintain essential to all other organized  structures ; but,
in addition to this, we  possess the special sense of touch,
which enables us to ascertain the  properties of bodies, for
almost all the physical  properties of bodies are capable of 
ORGANS OF SENSATION.
175
acting on the organs  of touch ;  form, dimensions, loco-
motion, and vibration, are all appreciated  by the organ of
touch.
  The whole cuticular surface may be said to have  a mo-
dified sense  of touch, and this kind of feeling is likewise
shared by the mucous  membrane  of the eyes,  nose and
mouth, the larynx, rectum, and the external genital organs.
But the hand only can be truly designated as the organ of
touch; the  hand is  expressly constructed for the purpose
of examining  the qualities  of objects :   the tips of  the
fingers especially have practically the finest discrimination
of the tangible qualities of bodies.   This delicacy of touch
in the fingers has given man  a great advantage over  the
animals : his touch is so delicate that it has been consider-
ed the source of his intelligence.   This sense is  capable of
arriving at a very great degree of perfection, as is seen in
many professions; and Magendie observes,  that, " for
medical men, a very delicate sense of touch is  absolutely
necessary."   This property then, of the nervous  system,
as before mentioned, which depends on the extreme  pulpy
distribution  of the posterior roots of the spinal nerves,  can
be assigned  only to man.


                       the hair.

   Hair  exists on almost all parts of the surface of  the
body  and limbs,  except  the palm of the hand and the sole
of the foot.
  The head is that  part  wherein the hair is most  abun-
dant ; it occupies the whole space corresponding with  the
occipital, the parietal, the squamous portion of the tempo-
ral, and the  upper part  of the frontal bones.  It seems to
be provided  as a protection against  mechanical injuries of
the head. The hair  on the face and other parts  is, in gen-
eral, much less,  though still in great quantity. 
176            ORGANS OF SENSATION.
   The difference in the nature of the hair considerably in-
 fluences it length ;  lank hair is generally the longest.  The
 more it curls the shorter it is, as exemplified in the African
 and even in Europeans.
   The  color of the hair varies considerably, according to
 the different countries, latitudes and climates.  Naturalists
 have considered the color of the hair, as well as that of the
 skin, as forming one of the characteristic distinctions of the
 human races.
   The eyebrows form  arches  to shade the eyes, and their
 motions are intended to protect them from the too power-
 ful impression of luminous beams.   Their actions also are
 very  expressive of the passions and mental emotions,
 which  affect the individual.   Painters have  paid  much
 more attention than anatomists to  the varied position of
 the eyebrows.
   The eyelashes have a similar  use; they moderate  the
 light, and likewise guard the eye  from substances floating
 in the atmosphere.
   The hair on the chin and upper lip is the peculiar attri-
 bute of  the male; and  appears towards  the period of
 virility, when the animal powers increase.
   The hair on the trunk varies most astonishingly; some
 men are almost completely hairy, whilst others are not at
all so.   Generally speaking, the fore part of the body pos-
 sesses much more than the back part:  in  men it is partic-
ularly met with along the median line of the chest.
   In both sexes a considerable  quantity shades the genital
 organs.
  The hair on the limbs, in man, is abundant on the whole
surface :  the proportion is the same in all, but its  length
and fineness vary considerably.  In  some it consists of a
mere down, in others it is coarse  and thick, giving  to  the
 limbs a hairy aspect. 
ORGANS OF SENSATION.            177
              organization  of the hair.

  The hair may vary in  respect to form, length, and fine-
ness, but its organization is the same in all.  It generally
arises from the subcutaneous cellular tissue: every individ-
ual hair originates in a bulb, or root, and each bulb has two
capsules, containing an oily fluid between them, which gives
color to the hair; a deficiency of  this is supposed to occa-
sion a change of the color, and the whiteness we observe
in advanced life.
   In general the color of the  hair has some relation to the
rete mucosum; as in the negro, the hair corresponds with
the tint of the skin, and in a person with light or with dark
colored hair, there is a florid or a dark complexion.
   The hairs in passing from the skin, are supposed to carry
with  them a  sheath of the epidermis, which is  thin, but
hard, and so transparent, as to allow the color of the hair
to appear through it.  With  the aid of a good  glass  we
may observe canals for containing their  nourishing fluid,
termed the medulla, which constitutes the coloring matter
of the hair.   The  chemical  properties of  the hair appear
to be of the  same  nature as  the epidermis, cartilage  and
the nails.
   The hair serves in general for ornament, to retain animal
heat, or to protect the different parts on or near which it is
situated.


                       THE  NAILS.

   The fingers are  provided,  at their  extremities, with a
 hard, transparent,  and flexible kind of plate, of  a similar
 nature to that of horn.
   The upper part of the nail, which is  concealed, forms
   vol. n.              23 
178
ORGANS OF SENSATION.
nearly a sixth part of its whole extent: its surface adheres
strongly to the epidermis, which, to fix it, is  disposed in
the following manner: — after having covered the portion
of the finger, corresponding to the last joint, it is  reflected
over the concave border, where the skin ends, and the nail
begins to emerge ; the epidermis having formed a kind of
ridge, is again reflected, insinuates itself between the skin
and the nail, and  adheres to the concave surface without
being confounded with  it;  for it is  easily removed by
maceration or with the dissecting knife.  Thus the  nail is
placed in a folding of the skin ;  there is, however, a cuti-
cular covering to it, which  appears  to be derived from a
lamina of the  epidermis.
  The nails strengthen and  defend the ends of the fingers
and toes ; they afford a support  to the ends of the fingers
in grasping bodies, and they are particularly useful  in taking
hold of  minute objects.
                      CHAP. VI.


                MUSCULAR SENSATION.

  To the sensitive department of the  fifth  pair, and the
compound spinal nerves, is  assigned  muscular sensation.
This is the sixth sense.  All  our conceptions of weight
and resistance, and motion in general, are derived from our
muscles.   The  muscular system, then, may be considered a 
ORGANS OF SENSATION.
179
distinct organ of sense as well as motion ;  each motion of
the invisible muscles is accompanied with a certain feeling,
which  may  indeed be complex, as arising from  various
muscles, but which is considered by the mind as one, and
it is this peculiar feeling, attending  the action of the mus-
cular fibres, which we distinguish from every other sensa-
tion.   To exemplify this, I might refer to the state of the
muscles in cramp of the limbs, and in rheumatic affections ;
in such morbid conditions their structure becomes painfully
sensible.  But let us call to mind the phenomenon which
every one must have  experienced, I mean  the feeling of
fatigue ; this is a muscular  sensation:  a sensation of which
the muscles are  the  organs,  as much so as the  eye,
and the ear, are  the organs of  sight and hearing.   Every
bodily effort depends on muscular contraction; and long
and frequent contractions,  that  is, continued exercise, oc-
casion a peculiar uneasiness which demands repose.  Pow-
erful and protracted exertions produce painful sensations to
the muscular sense : a more moderate degree of exercise is
attended with agreeable sensations.  With a healty state
of  body, there is a muscular pleasure in exertion. Thus
the child who is not playful, is not healthy.  There is a
muscular gratification, if I  may  so express myself,  in every
limb, in the games and pastimes of the school boy.
   Dr Brown, without being aware  that there was  a pecu-
liar set of  nerves  appropriated  to  muscular  sensation,
observes, that " nature in the other animals, whose sources
of  general pleasure are  more limited, has converted their
muscular system into an  organ of delight.   It is not in
search of richer pasture that  the horse gallops over the
field, or the goat  leaps from rock to rock, it is for  the lux-
ury of the exercise itself.  It is this appearance of active
life which spreads a charm over  every little  group with
which the  Deity  animates the scenery of nature."   We
may, therefore, consider that  the muscular system is not 
180            ORGANS OF SENSATION.
merely the living machinery of motion, but that it  is also
truly an organ of sense.
  The muscular sensation commences in infancy ;  there is
a feeling of danger when  the  child is  first  tossed  in  the
nurse's arms, and afterwards, when it essays to walk, there
is evidently an apprehension of falling.   Sir C. Bell* has
shown that we have a muscular sense, and that without it
we  could  have  no  guidance of our  frame;  that  we
could  not command our muscles  in standing, far  less in
walking, leaping, or running, had  we not a perception of
the condition of the muscles.
  Without a sense of muscular action or consciousness of
the effort made, the proper sense of touch could hardly be
an inlet to knowledge.  The property of the  hand in as-
certaining the size, the weight, the form, the hardness  and
softness, the  roughness or  smoothness of objects,  results
from the combined perception — through the  sensibility of
the proper organ of touch, and the motion of the hand,
arm and fingers.  But the motion of the fingers is especially
necessary to the sense  of touch ; they bend, extend, or ex-
pand  like palpa, with the advantage of embracing  the  ob-
ject, and feeling on all  its  surfaces  ; sensible to its solidity
and to its resistance when  grasped ; moving  round it  and
gliding over its surface, and, therefore, feeling every asperity.
  The same author has given  an  admirable description of
the pleasures arising from the  muscular sense.
  " The exercise of the muscular  frame is the source of
much of the  knowledge which is  usually supposed to be
obtained through the organs of sense ; and to this  source,
also, we must  trace some of our  own  chief enjoyments.
We may, indeed, affirm that it is benevolently provided
that vigorous circulation,  and, therefore, the healthful con-

  * Bridgewater Treatise.  On the Hand, its Mechanism and vital Endow-
ments.—p. 189. 
ORGANS OF SENSATION.
181
dition both of the mind and  the body, shall result from
muscular exertion and the alternation of activity and repose.
  " The  pleasure which arises from the activity of the body
is also  attended by  gratification  from the exercise of a
species of power — as in mere dexterity, successful pursuit
in the  field, or the accomplishment of some  work of art.
This activity is followed by weariness and a desire for rest,
and although unattended with  any describable pleasure or
local sensation, there is diffused  through every part of  the
frame,  after fatigue and whilst the active powers are sinking
into repose, a feeling almost voluptuous.  To this succeeds
the impatience of rest, and thus we are urged  to the alter-
nations which are necessary to health, and invited on from
stage to  stage of our existence.
  " We  owe other enjoyments to the  muscular sense.   It
would  appear that in modern times we know comparatively
little of the pleasures  arising  from motion.   The  Greeks,
and even the Romans, studied  elegance  of  attitude and
movement.   Their apparel admitted  of it, and their exer-
cises and games must have led to it.  Their dances were
not the result of mere exuberance of spirits and activity;
they studied  harmony in the motion of the body and limbs,
and majesty of gait.   Their dances consisted  more of the
unfolding of the  arms, than the  play of the  feet:  'their
arms sublime that floated on the air.'   The Pyrrhic dances
were elegant movements, joined to the attitudes of combat,
and performed in correct  coincidence with the expression
of the music.  The  spectators  in their theatres must have
had very different associations  from ours, to account for
the national enthusiasm arising from music, and their rage
excited by a mere error in  time.
   " This reminds us that  the  diversions in music in some
degree belong to the  muscular sense.  A man will put down
his staff  in regulated time, and the sound of his steps  will
fall into  a measure, in his  common walk.  A boy striking 
182
ORGANS OF SENSATION.
the railing in mere wantonness, will do it with a regular
succession  of blows.  This  disposition  of the muscular
frame to put itself into motion, with an accordance of time,
is the source of much that is pleasing in music, and  aids
the effect of melody.  There is thus established the closest
connection between the enjoyments of the sense of hear-
ing, and the exercise of the  muscular sense."
CHAP. VII.
                 VISCERAL SENSATION.

   I have elsewhere stated that the ganglionic department
of the nervous system belongs to organic life.  The whole
series of actions resulting from this department are instinc-
tive.   And we are conscious that the nerves of the ganglia
are the seat of certain sensations.   This is the seventh or
visceral sense.  The ganglionic nerves,  throughout the
whole  animal kingdom, preside over the organic or vegeta-
tive  functions, so as to control and direct their operation;
but their sensation or  perception, in man, is connected fre-
quently with certain  affections of the mind.  Magendie
said " the passions  were the triumph of the viscera  over
the intellect."  It is, however, with great diffidence that I
proceed to a description of this ganglionic  or visceral sen-
sation, although I am  convinced of its existence.
   1st.  In the viscera  of the chest;—strong mental emo- 
ORGANS OF SENSATION.
183
tion, as anger, first exalts, and then exhausts the powers of
the heart: and extreme grief, says Bichat, has been known
so to debilitate the circulatory powers, as to render  them
incapable of returning to their usual condition.  Desault,
the late  chief surgeon of the Hotel Dieu, has  remarked,
that  diseases of  the  heart,  and aneurisms  of  the  aorta,
were augmented  in number  during the Revolution, in pro-
portion to the evils which it produced.   The united  testi-
mony of mankind concurs in referring all the finer feelings
(sensations)  to the heart;  and  this view of the subject of
visceral sensation, I imagine must be confirmed by our own
individual experience and perceptions.*
   Of  this species of sensation is profound sorrow ;  it is
felt in  the lungs ; hence, the sense of oppression, anxiety,
suffocation, and involuntary sighs, which visibly agitate the
pulmonary organs.
   2d.  The  abdominal organs possess similar visceral  sen-
sation.  The stomach is affected  by any kind of trouble:
frequently it will cause a painful sensation  in that organ,
and  an interruption of the digestive  process ; and  the sad
forebodings and darker affections of the mind, have a sen-
sible effect on the digestive organs.
   It has  been very judiciously  observed by Haller, that
the sensation we experience in  parts receiving nerves from
the ganglions have a peculiar character; that they do not
resemble those experienced  in  such  parts as are supplied
with cerebral nerves.  Broussais ascribes the pleasure and
pain which accompany the exercise of the intellectual  facul-
ties, as having the same seat as the  pleasure and pain of

  *Dr Spurzheim denies that the feelings depend on the viscera of the tho-
rax or abdomen.  " The influence of the abdominal and thoracic viscera or
the manifestations of the mind is only mediate ; their functions contribute
to the organic  constitution of the brain  as well as of the body in general,
but they are not the seat of the affective faculties." 
184
ORGANS OF SENSATION.
the passions ; for the sensorium cannot feel without a cor-
responding feeling in the viscera.
   Are not hunger and  thirst also instinctive and visceral
sensations ?   Are they not important indications to the in-
dividual of the wants of the animal economy, and do they
not  incite the  animal to acts which  contribute and  are
essential to self-preservation ?   And the solicitation for food
and drink must be  obeyed, or alienation of the mind, or
death of the body must ensue.
   Hunger is characterised by a  peculiar sensation in  the
region of the stomach ;  there  is  a sense of drawing and
oppression in that, part, and when  the  cravings of hunger
are not appeased, it amounts to severe  pain in the stomach,
and a general feebleness of the whole frame.
   It might be easily  proved that  all the abdominal viscera
are capable of  transmitting impressions to the brain,  with-
out the intervention  of any external cause; and examples
might be  multiplied, were it  necessary,  to establish  the
theory of visceral sensation, without referring to  the morbid
states to which the internal organs are  liable.
   The ganglionic visceral feelings are instinctive, and con-
stitute a  separate department of sense; the impressions
conveyed by this department of the nervous system, to  the
common sensorium,  being totally dissimilar to those which
result from any other order of nerves.*

  * There are several species of sensation resulting from the ganglionic de-
partment, which, in an elementary work of this kind, cannot be discussed
even in the most transitory manner, but which may be compressed in the
generic term, visceral sensation, every species of which is instinctive;
namely, sensations determined by the viscera, and which solicit the nervous
centre to execute acts necessary for the exercise of their functions. 
ART.   IX.
ORGANS OF DIGESTION.
                     THE MOUTH.

  The mouth is circumscribed laterally by the cheeks, an-
teriorly by the lips, posteriorly by the velum palati, above
by the arch of the palate, and below by the tongue.  The
cavity of the mouth, and the organs which it contains, are
lined by a common mucous membrane.
  This membrane  forms  a fold  opposite the symphysis of
the chin, which is  named  the franum of  the under lip.
The mucous membrane passes into each alveolus, a pro-
longation of which adheres  to the roots of the teeth, and
indeed lines the cavities into which they are inserted.  Be-
neath the tongue we find  another fold, called  the franum
of the tongue.  This membrane  is then continued over the
epiglottis into the larynx and pharynx.
  About the middle of the lining of the cheeks we observe
the orifice of the parotid  duct, and in other parts a great
number  of mucous follicles.
  The lips are principally composed of muscles which have
been described;  they are  covered outwardly by the com-
mon integuments, and lined within by the membrane of the
mouth.
  vol. n.             24 
186
ORGANS OF DIGESTION.
  The lips possess a  small  proportion of adipose tissue;
but there is a considerable quantity generally found in the
cheeks, which give shape to  the face.


                     the  palate.

  The palate, or roof of the mouth, represents a kind of
parabolic arch; a white depressed line extends from  the
anterior to the posterior part of the palate, in the median
line of the body.
  On  the  arch  of the palate, the common mucous mem-
brane is much more dense and thick than on the other parts
of the mouth, and is  interspersed with small perforations,
which are the orifices  of mucous follicles, situated between
it and the osseous part of the palate.
  The gums  are continuous with  the membrane of the
palate, and are  formed of a similar kind of compact  red
tissue, the  intimate structure of which it  is  difficult to
explain :  they are,  however, prolonged  into the  alveolar
cavities, and send into the  root of each tooth  a  bulbous
process, named the pulp of  the tooth.
  The velum palati,'ox soft palate, is a soft, broad, mobile
partition, situated at the extremity of the palate, and sepa-
rating  the  mouth from the  palate.  Its upper edge is ad-
herent to  the arch  of the  os  palati;  its  lower  edge is
extended over the root of the tongue.   It  presents, at its
middle part, a prolongation,  termed the uvula;  which forms
the inferior edge of the palate into a double arch.
  The velum  palati acts like a valve, in preventing what
we swallow from passing into the nose.
  The pillars of the  velum palati  are united above, but
diverge below, and  are separated by a triangular space in
which the tonsils are lodged.
  The tonsils are of a light  red color, somewhat of the size 
ORGANS OF DIGESTION.
187
and figure of almonds ; they are  full of cells which com-
municate with  each other, and have large irregular open-
ings which convey a transparent  mucous  into the throat :
they are situated between  the anterior and the posterior
pillars of the soft palate, and close by the sides of the base
of the tongue.


                     the  pharynx.

  The pharynx is a  funnel-shaped  musculo-membranous
canal, situated behind the tongue ; it extends from the base
of the skull to near the middle of the neck ;  it rests on the
vertebral column,  and on  its sides  is in contact with the
common and internal carotid arteries, the internal jugular
veins and the pneumo-gastric nerves.   It is connected  with
those different parts by a cellular  tissue of a very extensile
character, and destitute of  adipose substance.
  Anteriorly, on a level with the nasal fossa and mouth,
the cavity of the pharynx is  open ;  opposite the commence-
ment of the trachea, it contracts, and terminates  in  the
cesophagus.
  The pharynx has several openings by which it commu-
nicates with the neighboring  cavities ;  two of these, called
the posterior nares, lead upwards and forwards; two  others,
called the Eustachian tubes, proceed  laterally to  the ears :
one passes forward, termed the fauces, or upper part of the
throat, to the mouth ; one downwards, through  the larynx
and trachea, to the lungs ;  and another, which is a contin-
uation of the  pharynx, leads  directly  downwards by  the
cesophagus to the stomach.
  The muscles of which it  is composed are the six con-
strictors, which have been described ; their fibres, which
differ in their obliquity, form  planes crossing each other in
different directions.   See vol. I. fig.  120. 
188
ORGANS OF DIGESTION.
  A mucous membrane lines the whole cavity of the pharynx,
which has a very deep red tint.  It is smooth, or  presents
only a few inequalities, arising  from  the presence of the
mucous follicles.
  The pharynx receives the aliments from the mouth, and,
by the action of its muscles, conveys them to the oesopha-
gus.  It also receives the air we inspire, and assists in the
modulation of the voice.
                   THE (ESOPHAGUS.

  The cesophagus,  or gullet, is  a musculo-membranous
canal, extending from the lower part of the pharynx to the
upper orifice of the stomach.
  It is situated between the trachea and the vertebrae, and
in the neck  it deviates a little to the left;  in the thorax it
proceeds behind the base of the  heart, and  between the
layers of the posterior mediastinum, from which it receives
a covering.  On entering the thorax, it passes downwards
upon the right side of the aorta.   It then perforates the
diaphragm, and, after a  very short course, arrives  at the
stomach.
  It is connected to the adjacent parts by a loose and ex-
tensile cellular tissue, which contains a number of lympha-
tic glands.
  Its outer surface is  smooth in its whole extent, and of a
red color above, but becoming paler as it descends : its in-
ner surface is whiter than that of the pharynx, and presents
longitudinal folds.
  The cesophagus, like the pharynx, is composed  of a
muscular coat, and  a mucous membrane.
  The muscular coat consists of two strata ; the external of
which has thick, strong, longitudinal fibres, somewhat fas-
ciculated ; the internal is formed of circular or  transverse
fibres, and is thinner than the former. 
ORGANS OF DIGESTION.
189
  The longitudinal fibres diverge toward the stomach, and
may be traced over its cardiac extremity, while the circular
fibres entirely disappear where the cesophagus terminates.
  The outer stratum of fibres  is fitted  for shortening and
relaxing, and  the inner for  contracting the canal, during
deglutition.
  The mucous membrane is soft, delicate and white ; it ap-
pears continuous above with  the membrane of the pharynx,
and  is formed  into  numerous longitudinal folds, arising
from the contraction of its muscular fibres.
  Between the muscular and mucous coats there is a dense
and compact cellular tissue,  to which the older anatomists
gave the name of the nervous  coat: it  is merely  the con-
necting  medium of the two former.
  The mucous follicles of the cesophagus are thinly distri-
buted ;  they are furnished with numerous foramina, which
supply a mucus for lubricating the passage  and  facilitating
deglutition.
  The office of the oesophagus is to convey the food from
the pharynx into the stomach;  for the aliment does not
descend into the stomach by its own weight, as we are able
to swallow solids or fluids with the  head more  dependent
than the stomach ; and, indeed, we  see animals  feeding in
this position, namely, with the head lower than the body :
it is, therefore, from a successive dilatation and contraction
of the muscular fibres of the canal, that the contents are
urged on to the stomach. 
190            ORGANS OF DIGESTION.


                         Fig. 60.
THE  STOMACH.
  The stomach  (ventriculus),  Fig. 60,  is the principal
organ of digestion ;  it is a conoid, elongated, musculo-
membranous reservoir: continuous on the one  hand with,
a, b, the oesophagus, on the other with,/, the duodenum.
It is  situated beneath  the diaphragm, between  the liver
and  the  spleen,  occupying  at  the  upper  part  of the 
ORGANS OF DIGESTION.
191
abdomen, the  epigastrium and  a portion  of  the left
hypochondrium.   The  stomach is destined  to  receive
the food from the cesophagus, and afterwards to convert it
into chyme, before transmitting it to the intestines.
   The dimensions of this organ  vary according  to the
quantity of aliment it contains;  it is much larger in those
individuals who eat much, than in other persons.
   The cardiac, or large extremity, h, is situated in the left
hypochondriac region, approaches  the spleen, and  is con-
siderably higher than the small extremity.
   The upper surface, g, is turned towards the  diaphragm,
the under, towards the intestines ; but when  we examine
the abdomen after death,  unless  the stomach is consider-
ably distended, it falls on the spine, so that the superior
surface becomes anterior,  and the inferior surface posterior.
   The large curvature, e,  is situated obliquely forwards and
downwards ; the small curvature, d, is opposite to the large
 one, and  towards the spine.
   The left, or cardiac aperture, of  the stomach, is the ter-
 mination  of, b, the oesophagus.
   The right aperture, or the pylorus,  c, terminates the
 stomach to the right, and communicates with,/, the duo-
 denum :  it  consists of a duplicature of the two inner tunics,
 which project into the passage, dividing the stomach, and
 intestines ;  it contains circular  muscular fibres, called the
 sphincter pylori:  or, I  should rather describe  it, as a solid
 fibrous ring, interposed between the peritonseal and  mucous
 surface of the pylorus.


          THE ORGANIZATION OF THE STOMACH.

    The stomach  is formed of three membranes, a serous, a
 muscular, and a mucous; these are connected together by
 cellular tissue, and supplied with vessels and nerves. 
192
ORGANS OF DIGESTION.
   The serous membrane is merely the peritonaeal covering,
and, in this situation, has a transparent, smooth and white
appearance; it is externally lubricated by a serous fluid.
It is united to the muscular membrane by a cellular tissue.
   The  muscular  membrane, or  tunic, is composed of pale
fibres, disposed in three different directions.   1st. Some of
these fibres, which  are  more longitudinal, are superficial;
others,  which are  extended over the surface, are more
irregularly distributed.  The 2d plane of fibres lies imme-
diately under the former ; these fibres are circular, and run
parallel to each  other.  In the 3d  series the fibres are
oblique, and may be observed  in  broad fasciculi upon the
extremities of the stomach.
   A layer of dense cellular  tissue unites  the muscular  to
the mucous tissue.  This layer has  been very improperly
named, by the old anatomists, the nervous coat.
   The mucous membrane, or tunic, forms the  inner surface
of the stomach ;  it  is of a pale pink  color,  and  marbled
appearance, crowded with villosities  which seem to consti-
tute a downy and colored tissue, continually  covered with
an abundant, viscid, inodorous fluid.   When the stomach
is empty this membrane, from the contraction of the mus-
cular fibres, presents numerous wrinkles, which are termed
the ruga of the stomach.
   This surface has a velvet-like appearance,  and when in-
jected and examined with a powerful lens, we find it form-
ed of fine, short, prominent villi, which are crowded with
an infinity of small vessels, whose office is to furnish that
particular fluid, called the gastric juice, which is the prin-
cipal agent of digestion.
   There is also a number of orifices on the mucous mem-
brane ;  these  are the  openings  of the  mucous  follicles,
which are distributed in very regular order. 
ORGANS OF DIGESTION.             193
               OFFICE  OF THE STOMACH.

  It is the office of the  stomach to receive the food after it
is prepared  by mastication,  likewise liquid nutriment  or
other  fluids, and  to  secrete the gastric juice, and subse-
quently to transmit the digested mass  to the  small intes-
tines.   In the stomach,  the food is converted into chyme by
the solvent power of the gastric fluid, which gradually acts
on the ingesta, from the  superficies to the centre of the
mass,  and as soon as a portion of it is reduced to a homo-
geneous consistence, it passes into the  duodenum, without
waiting till the same change has pervaded the whole.
  The stomach is amply furnished with nerves from each
nervous  department,—hence,  its great  sensibility to  all
kinds of stimuli, and its disturbance by mental causes, —
hence, also, the surprising sympathy  existing  between it
and most functions of the system, so that the healthy con-
dition of the stomach actually depends upon the tranquillity
of the mind.
                THE  INTESTINAL CANAL.

  The intestinal canal extends from the pylorus to the anus,
and in the  human subject varies  from thirty to  thirty-five
feet in length.  It is coiled on itself,  so as to form  folds or
convolutions, and  is divisible into two parts, differing in
size and situation, as well as external conformation, the di-
vision between them being moreover  marked by  a  peculiar
valvular structure, which prevents a  reflux of the ingesta
after they have  passed beyond it.  The part of the  canal
between  the pylorus and the valve just referred to, is called
the  small  intestine, the remainder thence  onward to the
anus, the large intestine.
  vol. n.              25 
194
ORGANS OF DIGESTION.
                THE SMALL INTESTINE.

  The term small intestines  is calculated to give us a false
idea of the nature of the smaller portion of the alimentary
canal, the small  intestines being only one continued cylin-
drical tube, but on account of the situations of its various
parts, or other circumstances which will  subsequently be
adverted  to,  it  is convenient to distinguish it into three
divisions; namely,  the  duodenum, the jejunum,  and the
ilium.
                    THE DUODENUM.

  This portion of the intestines differs, however, so mate-
rially from the others, as scarcely to admit of the above ar-
rangement ; for it is not invested with a serous membrane,
the peritoneum  being only partially applied  upon it in a
small extent, nor is it supported by the  mesentery, and its
volume is so large, that it frequently equals the stomach in
size ;  for this  reason, and  others which will be presently
noticed, it has obtained the name of ventriculus  succentu-
riatus.
  The duodenum is so named on account of its length  be-
ing commonly estimated at twelve  fingers' breadth ; it is
that portion of the intestinal  canal, which  immediately
succeeds to the stomach ;  it occupies  the  middle part of
the abdomen, where it is concealed  by the transverse me-
socolon and the stomach.
  The duodenum  commences  at the valve of the pylorus,
where it is  covered in the greater part of its extent by the
peritonaeum ;  here we often observe it tinged yellow by the
transudation of bile from the gall  bladder.   The intestine
we are  speaking of proceeds horizontally backwards,  and 
ORGANS OF DIGESTION.
195
to the right, to near the neck of the gall bladder;  then de-
scends vertically to the left, as far as the third lumbar ver-
tebra, and terminates by being  directed upwards  and for-
wards, towards the  extremity of the mesentery, above the
superior mesenteric vessels.
  The duodenum,  consequently,  forms  a kind  of semi-
circle, having its convexity to the left, and embracing the
pancreas in its concavity.
  The inner surface of the  duodenum,  like that of the
stomach, is covered by a  mucous  membrane, upon which
we may observe  a number of folds, more or less, surround-
ing the intestine, and  very close  to each
other; these are the valvula conniventes.
Fig. 61, represents the inner surface of a
portion of  the  small  intestine.   These
valves are formed by plaitings of the mu-
cous membrane  only,  and   they  project
three or four lines into its cavity.
   In the interior of the duodenum we ob-
serve a small tubercle, at  the point of
which are seen the united or separate ori-
fices of the ductus communis choledochus
and the pancreatic ducts.
THE  JEJUNUM  AND  TLIUM, PROPERLY  CALLED  THE SMALL
                      INTESTINE.

  The small intestine is continuous with the  duodenum,
without any distinct line of demarcation to distinguish it.
The  small intestine is the  longest portion of the digestive
canal, its length being about twenty-six feet, or five times
that  of the whole body.  It forms a  number of curves, of
which the concavities are  connected with  the  mesentery,
 
196
ORGANS OF DIGESTION.
while the convexities are free and floating, and folded upon
each other in different directions a number of times, form-
ing what are termed convolutions.
  Fig. 62, a portion of the mesentery and small intestine
removed from  the  body, and  suspended by,  a,  a, two
threads attached to the mesentery; b, b, b, the convolu-
tions of the intestine attached to it; c, one of the  mesen-
teric glands.
  The small  intestine commences under the superior me-
senteric vessels, and terminates in the coecum.   Anatomists
usually divided it into two portions, although it is impossi-
ble to assign distinct limits to  each of  them.   The upper
portion is named the jejunum,  from its  being commonly
more empty than the other part  of the intestine;  the other
is called the ilium, from  its  position in  the  fossse  of that
name.   The jejunum occupies the upper part of the um-
bilical region, the ilium  extends as  far as the hypogastric 
ORGANS OF DIGESTION.
197
and iliac regions.  An examination of the  small intestine,
however, shows  no natural division of this kind, so that
the limits of the two portions are quite arbitrary.
  Its whole outer surface is perfectly smooth, and contain-
ed between the two  laminae of the mesentery ;  its inner
surface has the same structure and appearance as the duo-
denum ;  the  villi of the  small intestine are  larger  than
those of the  stomach; there are about  four thousand to
the space of a square inch, and  their length is about one-
fourth of a  line : but the valvulae conniventes are gradually
less conspicuous as they are examined towards the coecum.
   The muscular membrane is  interposed between the two
others;  its fibres are pale and not very  apparent; the
superficial  layer  is longitudinal  and the deep  fibres are
curved  in  the transverse direction  of the intestine; not
passing entirely round it,  but  like the longitudinal are in-
terrupted from space to space and seem composed of shorter
fibres,  whose  extremities  pass between  each other.  The
longitudinal fibres shorten the canal, and the circular fibres
diminish its calibre; together  they  produce an undulating
movement of the intestine termed the peristaltic motion.


          THE LARGE INTESTINE.  See Fig. 64.

   The large, like the small, intestine forms one  continued
alimentary canal, the former extending from the termina-
tion of the ilium to the anus.   The  large  intestine, how-
ever, is distinguished not  only by its size, but by its outer
surface presenting irregular enlargements and depressions,
interrupted in  three  places by longitudinal bands of mus-
cular fibres.   One of these  depressions is anterior; the
other two are posterior ; the annexed figure shews its form
and its  course better than any verbal description.   Its
length is that of the body, or about  six feet.  Its volume 
198
ORGANS OF DIGESTION.
is generally triple that of the small intestine, and it also
differs from it in  having papillae of fat, called appendices
pinguedinosa, attached  externally to it.
   Like the small  intestine, it  is distinguished into three
portions; termed the coecum, the colon, and the rectum.
   The coecum is  only three or  four  inches  in length, and
nearly the same in  diameter ;  it consists of that part of the
intestine which is under the extremity of the ilium.   It is
situated in the right iliac region, resting on the cavity of
the  corresponding  os ilium.   The inferior part forms a
closed  sac, the  mouth of which  is directed towards the
colon.
   At the left extremity of the coecum there is a process of
about the same length, and of the same nature with  itself,
but the diameter is not larger than that of a writing quill,—
termed the appendix cozci vermiformis.   It is hollow in its
 whole extent, and  communicates with  the  coecum.   It is
constantly filled  with mucus, but its uses are entirely un-
 known.   We must  again recur to the union of the  small
 intestine with the large ; at the opening of the former into
 the latter is situated the ilio-ccecal valve, or the valve ofBau-
 hin; this, however, is merely a projecting of the intestinum
 ilium into the coecum, so  that the  folding of its extremity
 does not prevent the faeces from passing downwards, but,
 by the pressure of the edges against the sides, and the con-
 traction of its muscular fibres, it offers a resistance, under
 most circumstances, to a retrograde movement of the con-
 tents of the intestine. 
ORGANS OF DIGESTION.
199
Fig. 63.
  Fig. 63, exhibits the insertion of the small into the large
intestine, the drawing from which this was taken was infla-
ted, dried, and a large opening cut into it to show the valve.
  a, the intestinum ilium,—
  b, its valvular opening into the cavity of the colon.
  c, the caput coeci.
  d, the appendix coeci vermiformis.
  e, a portion  of the colon.
  The colon forms  the  most considerable portion of the
large intestine ; it nearly encircles the small intestine, and
is a continuation of the coecum, or that portion of the in-
testine which is extended from the right iliac region to the
left.  The colon commences at the coecum, and terminates
in the rectum.
  The colon ascends in the right lumbar region, over the
kidney of that side, and is  here termed the ascending colon.
  From the kidney it  proceeds  forwards, and crosses the
abdomen in the epigastric and hypochondriac regions, be-
neath the stomach and above the small intestine; it is here
called the transverse arch of the colon.
  On the right side the arch is situated under the liver and
gall bladder, the latter of which, after death, usually stains 
200
ORGANS OF DIGESTION.
it with bile.  In  the  hypochondrium it turns backward
under the spleen, and  descends in the left lumbar region
in front of the kidney, to which it is closely connected; in
this situation it is called  the descending colon.
   In  the iliac region it forms a double curve,  compared in
shape to the greek letter g, and hence  termed the sigmoid
flexure of the colon.   It  is surrounded in nearly its whole
circumference by the peritonaeum, which fixes  it above and
behind, by means of an  extended and loose  fold, termed
the iliac mesocolon.
   The rectum has its name from being nearly a right line,
extending from the last lumbar vertebra  to the anus : it is,
however, accommodated to the curve of the sacrum.  The
rectum is smaller than the coecum or colon, but is capable
of great dilatation, and does not present those  intersections
and muscular bands which we find in the other portions of
the large intestines.   At the  anus it contracts into a nar-
row orifice, the sides of which are compressed into close,
longitudinal folds, by the sphincter ani and the two  leva-
tores  ani.
   The structure of the large intestine is the  same as that
of the small  intestine, but it is  less muscular.   The  villi
of  the inner part are smaller, the mucous glands or fol-
licles  are very apparent,  and  there are no valvulae conni-
ventes.  The most characteristic distinction in the general
appearance of the  large  intestine, is  the intersected  and
cellular  divisions throughout its whole extent.  These
cells retain the matter, and prevent  its too rapid descent
into the rectum, and thus allow time for the lymphatic ves-
sels to collect the fluid from the digestive canal. 
ORGANS OF DIGESTION.
201
Fig. 64.
  Fig. 64, exhibits  the  sacculated appearance and course
of the large intestine.
  a, the caput coli.
  b, the ascending colon.
  c, the transverse arch of the colon.
  d, the descending colon.
  e, the sigmoid flexure of the colon.
  /, the rectum.
  g, the mesocolon.
     vol. ii.               26 
 202             ORGANS OF DIGESTION.

   h, the termination of the ilium.
   i, the appendix coeci vermiformis.
   k, k, k, k, appendices pinguedinosae.


                    THE MESENTERY.

   The mesentery is formed by the peritonaeum,* which ad-
vances from the parietes of the abdomen, and includes the
intestines in a duplicature of it.  The mesentery is situa-
ted in the middle of the intestines, commencing at the last
turn of the  duodenum, and proceeding  obliquely down-
wards and towards the right side, along the vertebrae of the
loins, to the first, second, and third, of which it is  chiefly
connected.
   Its anterior edge is more extensive than  the posterior, as
it corresponds  to  the  convolutions of the  intestines which
are prevented  by it from being entangled in the various
motions of the body.
  That part which connects the  small intestine to the spine
retains the  name of mesentery ; the  other, which belongs
to the colon, the mesocolon; a portion also which  is con-
tinuous with the latter, and is connected with the rectum,
is called the mesorectum.
  The office of the mesentery is to suspend, connect, and
retain the intestinal canal in its proper situation ; at the
same time allowing it  a  certain degree of motion ;  it also
furnishes it  with  an exterior covering, lodges numerous
glands,  and  affords  a  support to the vessels and  nerves
which are distributed to the intestines.

  * The peritonaeum is a serous membrane investing the inner surface of the
abdomen, and prolonged under the form of an envelope over most of the
viscera contained in it. See  Article XVI. 
ORGANS OF DIGESTION,
203
                      DIGESTION.

  Our food in general is first submitted to the  mechanical
process of  division by the teeth;  and during its  masti-
cation it  becomes  intimately mixed and  combined  with a
chemical  solvent, which prepares it for the process it has
shortly to undergo  in  the  stomach.  This solvent is the
saliva. The  glands appointed to produce this fluid seem
to act in  sympathy with the stomach, being with it simul-
taneously excited by the stimulus of the  food, " or even
(says Dr. Paris) by the contemplation of a favorite meal.'1
  When  the  alliment is  introduced into the stomach, it
appears to remain  there a short period before it undergoes
any change ;  but the solvent  energy of the peculiar fluid,
which has already been referred to under the appellation
of gastric juice, soon produces  that change upon the ali-
ment called  the digestion, which converts the food into
CHYME.
  The exact  nature of chyme  is not easy to describe ; but
physiologists  agree  in considering it a  homogeneous paste,
grayish, of a sweetish  taste,  slightly acid, and retaining
some of  the properties of the  food.  Magendie has lately
examined the subject  with great  precision, and it follows
from  his experiments, that there  are  as many species  of
chyme as there  are varieties of food ;  if, at least, we may
judge by color, consistence and sensible qualities.   What-
ever be the nature of the alimentary substance, introduced
into the stomach,  the chyme will possess the  invariable
property of an acid, reddening litmus paper, and it always
has a sharp odor and taste.  As the parts of the food are
digested, that is, converted  into  chyme, they pass out
of the stomach  into the duodenum, there to undergo fur-
ther changes.   In this process the pylorus must, as  its
name implies, be endowed with a  peculiar sensibility, and 
204
ORGANS OF DIGESTION.
 vigilance, by which it is enabled to distinguish between the
 crude and  chymified portion, so  as to  admit the latter,
 while it usually opposes the  exit of the former.   Some-
 times the pylorus seems so far to  resist  the egress of the
 contents of the stomach as  to occasion  an inverted action,
 and to expel the food by vomiting.
   If a  liquid holding  nutritive matter is  taken into the
 stomach, it is either coagulated by the gastric fluid, or its
 watery  part is absorbed, and the solid matter deposited in
 the stomach; in both cases  the product is afterwards chy-
 mified in the manner  already described.   Part of the liquid
 passes through  the pylorus into the intestines,  to be  ab-
 sorbed with the  chyle, or to be rejected with the  feces ;
 and a large portion of the liquids is conveyed directly from
 the stomach into the circulation.
   Many anatomists have considered the duodenum as a
 subordinate stomach, for,  immediately  the  chyme  has
 arrived  at  this  part of the  alimentary  canal,  it becomes
 converted  into a more highly  animalized product, termed
 chyle,  or the  milk-like fluid which  is  imbibed by the
 lacteals.  Chyle has been frequently chemically examined,
 but  it presents  a difference in composition, according to
 the nature  of the aliment from which it has been elabora-
 ted.  If the animal has eaten substances of a fatty nature,
 the chyle will be found milky white, a  little heavier than
 water, with a strong and peculiar odor, and a saline  and
 sensibly alkaline  taste;  but if the food should  not  have
 contained fat, it  will  be opaline and almost  transparent.
 Very soon after chyle  is extracted  from the living animal,
 it becomes  firm,  by coagulation : it then  gradually sepa-
 rates  into three distinct parts ;  the one solid, which remains
 at the bottom of the vessel, the second  liquid, and a third
 that forms  a  very thin layer  at the  surface.   The more
 solid part seems to be an intermediate substance between
albumen and fibrin, for it unites several properties common 
ORGANS OF DIGESTION.
205
to both.   The liquid part of the chyle resembles  the serum
of the blood ;  the other  part  which  appears on  its surface
is a fatty substance, which imparts to the fluid the appear-
ance of milk.   The comparison, however, which has been
made between chyle and milk has no real foundation ;  for
the former contains nothing which exactly agrees with the
constituents of the latter.
   The  lacteal vessels which  absorb  this fluid have  been
already described ; they  commence  in  the very extended
valvular apparatus of the mucous  membrane of  the  intes-
tine, by thousands and tens of thousands of orifices  which
imbibe the chyle.*
   The function, consequently, of the small intestine  is to
separate the  nutritious  matter from the feculent, and to
convey the latter into the colon.  In its  progress, the nu-
tritive principles of the aliment having been absorbed into
the circulation, the residue is  urged  forward by  the action
termed the peristaltic motion; the ingesta losing, as it pro-
ceeds towards the coecum, any portion of the chyle  which
may have escaped the lacteals in the  first portion of the
small  intestine.  The remainder  of the contents  accu-
mulates to a certain extent in the colon, and acquires the
peculiar fetor which distinguishes the feces.  In  its pas-
sage in this part of the digestive  canal,  it is considerably
retarded by the cells or compartments into which the large
intestine  is  divided.   But  the principal function of the

  * It is probable that the mesenteric  glands through which they pass pro-
duce an important change  in  the chyle ; but the nature of this change is
wholly unknown : it is certain that these glands secrete a fluid, which may
be compressed from them with  the fingers ; hence, some physiologists have
supposed that they add a fluid to  the chyle  in order to purify it; while
others, again, have contended that their use is to produce a more intimate
union of the aliments which compose it.  The chyle is, at length, poured
into the thoracic duct, together  with the lymph which is brought from all
parts of the system, by the absorbent vessels, and together they furnish new
materials to repair the waste which the body is perpetually undergoing. 
206
ORGANS OF DIGESTION.
large intestine, is to imbibe the  remaining fluid in propor-
tion to the wants of the system ; another office  obviously
performed  by this  portion of the alimentary canal  is to
carry out of the  system the waste, incident to the changes
of the  economy, which  is  not  removed  by the kidneys.
The fecal matter as it passes along the colon gradually be-
comes more solid, and at length, when it enters the rectum,
it  forms a mass of considerable bulk, which  distends its
parietes, and then  creates  a sensation of uneasiness, which
announces the necessity for relief. 
ART.   X.
ORGANS OF RESPIRATION.
                      THE LUNGS.

  The lungs are two cellular, or spongy organs, occupying
the greater part of the cavity of the thorax: they are sep-
arated from each  other by the  mediastina  and the heart,
and are surrounded by membranes which are named pleurae,
with which they are in  contact, so that no air can intervene
between them, unless an opening is made into the bag of
the pleura, when  the lungs would instantly collapse.
  In figure they are somewhat  conical, their shape corres-
ponding exactly with the cavity of the  thorax, being round-
ed towards the ribs, and  irregularly  depressed towards  the
mediastinum and heart.   In  all instances, the volume of
the lungs is in  proportion to the capacity of the thorax,
and they are compressed or  dilated according to the ex-
pansion or contraction  of the parietes ; nor (in  a healthy
state of these organs) does any  vacuity exist in the interior
of the chest.
  The color of the  lungs is a pale  yellowish  red, more
florid  in children, and of a deeper and purple hue in age ;
but the lung is always more colored on the side on which
a dead body has lain ;  but this deeper tinge is owing merely 
208
ORGANS OF RESPIRATION
to the blood, from its own  gravity, falling to the most de-
pendent part of the lung.  The general color of the lungs
is also interrupted by small black spots, irregularly dispers-
ed on their  surface, and  more  or less numerous, some of
which are entirely superficial, others penetrate more or less
deeply into  the  tissue of the lungs.   These spots do not
appear till the age of ten or twelve years.
  The specific gravity of the lungs is much less than that
of the other organs ; when in their natural state, they swim
in water, and this lightness depends upon a large quantity
of air penetrating their whole tissue.   In infants, umo  have
never breathed,  the  lungs generally sink  if immersed  in
water.  The absolute weight, however, of the lungs varies
in different individuals, depending on the  greater or less
quantity of  blood remaining in  them at the moment  of
death. 
ORGANS OF RESPIRATION.           209
  In this figure (65) the ribs are sawn through at the sides,
and the anterior parietes of the thorax removed, in order
to exhibit the natural situation of the lungs.
  a, a, a, the three lobes of the right lung.
  b, b, the two lobes of the left lung.
  c, the anterior mediastinum.
  d, the  thyroid gland,  situated on the trachea.
  c, the  thyroid cartilage.
  VOL. II.              27 
210
ORGANS OF RESPIRATION.
              ORGANIZATION of the lungs.

   Each of the lungs is divided into sections, called  lobes,
varying in depth in different bodies.  The right lung con-
tains three lobes, the left two;  each of which lobe is sub-
divided into lobules,  which  are  of different sizes and of
irregular angular forms;  distinct at the exterior, and  sepa-
rated from each other by whitish grooves of cellular tissue.
Each of these  lobules is again divided  into air cells, the
intricate structure  and figure of which are unknown.
   The pulmonary  lobules, therefore, are formed of a spongy
tissue, the areola  of which are so  small  as  to require a
powerful  lens  distinctly  to  observe them:  these areola?
communicate with  each other, and are surrounded by a thin
layer of cellular tissue, which separates them from the ad-
joining lobules.
   One of the branches of the air tubes (bronchi), and the
pulmonary artery,  are distributed  to the lobule, and the lat-'
ter then terminates in the radicles of the pulmonary veins.
This is  proved  by  injecting colored water into the pulmo-
nary artery, when  the injected matter immediately passes
into  the pulmonary veins ; but, at the same time, a  small
portion enters  the bronchi: this  circumstance  establishes
the fact of the  intimate connection  between  the organs of
respiration and circulation.
   The outer surface  is  covered  by a glossy serous mem-
brane, named the  pleura* which will be subsequently de-
scribed.
   The lungs are very elastic, and constantly kept in a state
of distention by the pressure of the atmosphere  : this  is
proved by puncturing the parietes of the thorax, when they
instantly collapse.   During inspiration the  intercostal  mus-
* See Article XVI. 
ORGANS OF RESPIRATION.
211
cles raise  and draw out the ribs, and  the diaphragm de-
scends ; the enlargement of the thoracic cavity follows of
necessity the greater distention of the lungs, from the di-
minished resistance to the air gravitating in the bronchi and
pulmonary areolae.   The diaphragm and muscles of respi-
ration  ceasing to act, the substance of the  lungs, from its
elasticity,  recovers  its  former dimensions, and expels the
additional volume of air just admitted, and the respiratory
muscles follow the shrinking substance of the lungs, offer-
ing from their relaxation no resistance to the  atmosphere
pressing on the surface of the chest and abdomen.   Thus
expiration is produced : thus the lungs  are continually ex-
panding to admit  the atmospheric air, or  contracting to
expel it, from the hour of birth  to the latest moment of our
existence.   This alternation occurs in an adult at rest about
twenty times in  a minute — once to about three pulsations
of the heart — this  will give twentyeight  thousand  eight
hundred inspirations in twentyfour hours.
   The mean quantity  of air that enters the  lungs at each
inspiration, is forty cubic inches ; and the ordinary quantity
of air  contained in  the lungs is two  hundred and eighty.*
Thus,  supposing twenty inspirations in a minute, the quan-
tity of air that would enter and pass out in this time would
be eight hundred inches, which make fortyeight thousand
in the  hour, and in twentyfour hours  is one  million one
hundred and fiftytwo thousand cubic inches.
   Inspiration and expiration are intended to renew, in part,
the mass of air contained in the lungs :  it may be here re-
marked, that the portion of air expired, is not  exactly that
which was inspired  immediately before, but a portion only
of the quantity which  the lungs contained after inspiration.
   The office of the lungs is to produce certain atmospheric
changes in the blood, which are essential for  the support of
life. °
* Dr. Thompson. 
212
ORGANS OF RESPIRATION.
  The air in its passage  to the lungs, by passing  through
the mouth  or the nose,  the pharynx, the trachea, and the
bronchi, becomes of a similar  temperature with the body,
and is charged with the vapor which it carries from the air
passages ;  and in  this state, rarefied and humid, it arrives
in the pulmonary lobules, to mix with that which the lungs
contained before.
PHYSICAL AND CHEMICAL CHANGES WHICH  TAKE PLACE IN
                      RESPIRATION.

   The air, in its exit from  the  lungs, partakes of the tem-
perature of the body ; there escapes with it a great quan-
tity of aqueous vapor, called pulmonary transpiration, and
its chemical composition is very different from the inspired
air.
  The atmospheric air we breathe contains 021 of oxygen,
and a trace of carbonic acid ; the  air which passes out of
the lungs contains 0*14 or 0-15 of oxygen, and 0-6 to 0-7
of carbonic acid :  generally, the quantity of carbonic acid
is less than the quantity of oxygen which has disappeared.
  The quantity of oxygen consumed by an adult, accord-
ing to Lavoisier and Sir H.  Davy, is thirtytwo cubic
inches in a  minute, which  gives, for  twentyfour  hours,
fortysix thousand and thirtyseven inches.
  We may, therefore, easily calculate the quantity of car-
bonic acid that  passes  out of the lungs  in the same time,
since  it  nearly represents the volume of oxygen  that  has
disappeared.   Thompson values it at forty thousand cubic
inches, though, he says, it is probably a little less :  now this
quantity  of carbonic acid represents twelve ounces of solid
carbon.
  If we are attentive to our respiration, we shall find  the
degree of alteration that the air undergoes in our lungs, by 
ORGANS OF RESPIRATION.
213
a feeling which inclines us to renew it: if the  breathing is
suspended for many seconds,  there  is anxiety and fear,
and, as it were, an instinctive warning of the importance of
respiration.
   The changes of the quality of the air during respiration
have been described, in which time the  blood circulating
through the lungs also undergoes a corresponding and re-
markable  alteration.  That the oxygen  exerts an agency
on the blood, is a fact shown by direct  experiments ; the
blood, whether arterial or venous, when agitated in contact
with common air, imparts carbon, and converts the oxygen
into carbonic acid: it is, therefore, a fair inference that, in
the body, the change of inspired oxygen into carbonic acid
is effected in the  same manner.   In the areolae, or air cells
of the lungs, the  oxygen  may be  considered as almost in
contact with  the blood contained in the ramifications of the
pulmonary vessels ; inasmuch as nothing but the exceed-
ingly  thin  substance of the vessels is  interposed.  When
the oxygen of the air is taken  into the lungs, after  a mo-
mentary contact,  as it may be called, with the blood, it is
discharged again during expiration; but part of it has com-
bined with carbon.   As it regards this combination, there
have been two opinions.   The one is that the oxygen of
the air instantly dissolves, and combines with the carbon-
aceous matter found in the blood, and immediately after is
expired as carbonic acid.  The other is, that the oxygen of
the air is absorbed by the blood in the lungs; that it  circu-
lates with the  blood  throughout the whole system, during
which it combines with carbon ;  and that, on the  return of
the sanguineous  current  to  the  lungs, the  carbonic acid
thus produced exudes through  the coats of the minuter
vessels,  and is expired.  This latter opinion is most proba-
ble.   For if blood is merely exposed to the atmosphere for
the space of three minutes, no change is produced ;  but if
it is agitated with it during the same time, carbonic acid is 
214           ORGANS OF RESPIRATION.
produced.  Independently of the evidence afforded by this
experiment, it might be reasonably expected that the car-
bon of the blood would require more than an instantaneous
contact with  the  oxygen of the air, before a combination
could take place.   Such a  condition would be fulfilled, if
the oxygen were to circulate with the blood for two minutes
and a half; for this, as far as is known, is the space of time
which the whole  volume of the blood  requires to  travel
from  the  lungs back again to  the lungs; and this is the
space of time  found necessary to  continue the agitation
of the blood  in  the experiment just named.  If in that
experiment, actual contact of the blood with oxygen during
three minutes  did  not  evolve  any carbonic acid, it would
be singular if, in the lungs, carbonic  acid could be formed
during the time occupied by.one inspiration, especially as the
substance  of the blood-vessels and air tubes are interposed.
  To confine the  office of  the  lungs to the mere removal
of redundant carbon from venous blood, is to take a limit-
ed  view of its operation, and  to underrate the utility and
necessity of the complex and  astonishing  mechanism  by
which so simple an object would be accomplished.   To the
process of respiration, the   construction of the chief parts
of the animal system are subservient; if  respiration be sus-
pended, so is life:  even the atmosphere is constituted in
such a way as to  conduce to the due performance of this
function.   We know the important and  extensive agency
of oxygen in creation:  can we doubt in the laboratory of
the body, where chemical   changes  are  incessantly taking
place, that oxygen is less constantly in demand ?  And is
it not probable that the medium of supply of oxygen to all
these parts is that obvious one, which, in order to receive the
supply, is  presented in thousands of currents, to thousands
of currents of air, the  absorption being promoted by the
two most efficacious means — motion and extensive surface?
  The view here  taken of the phenomena of respiration 
ORGANS OF RESPIRATION.
215
corresponds with the conclusions  arrived at, from an ex-
tended series of experiments made by Dr. Edwards * who
appears to have established four fundamental points.
  1st.  The absorption of oxygen, which disappears.
  2d. The exhalation of carbonic acid, which disappears.
  3d. The absorption of azote.
  4th. The exhalation of azote.
  The oxygen which disappears in  the  respiration of at-
mospheric air is wholly absorbed.  It is afterwards wholly,
or in part, conveyed into the circulation.   It is replaced by
exhaled carbonic acid, which proceeds wholly, or in  part,
from that which is contained in the mass of the blood.
  An animal breathing atmospheric air also absorbs azote;
this is likewise conveyed wholly, or in part, into  the  mass
of blood.
   In different individuals,  it has been found that different
quantities of oxygen is consumed, and of course different
quantities of carbonic acid returned.   The breath expired
has been shown to contain  from  six  to  eight per cent of
carbonic acid.   Drs. Prout and Fyfe have proved experi-
mentally, that particular conditions of body or mind render
the quantity of carbonic acid variable.   The former has
shown that the quantity depends also  on the time of  day :
at noon it is at its maximum; it decreases  until nine at
night;  it then remains  at  its minimum for six hours, and
at four in the morning it begins to  increase.   Probably it
may vary likewise with the  seasons of the year.  The
above were the  results obtained in the month  of August.


              THE TRACHEA  AND BRONCHI.

   The  trachea is a cylindrical fibro-cartilaginous and mem-
branous tube, a little  flattened posteriorly.   It is situated
* On the Influence of Physical Agents on Life. 
216           ORGANS OF RESPIRATION.
before the vertebral  column, in the posterior mediastinum,
resting on  the  oesophagus, which however, inclines some-
what to its left side, and extends from the lower part of the
larynx to opposite the second or third dorsal vertebra.  It
is inclosed  between the great vessels of the neck, and  cov-
ered partly by the thyroid gland, and its veins, also by the
sterno-hyoid  and  sterno-thyroid muscles, and crossed by
the vena innominata, the arteria innominata, and the  arch
of the aorta.  At the second or third  dorsal vertebra it di-
vides into  two  lateral  branches, termed  bronchi, one  of
which passes to the right lung, and the other, which is the
longest of the two, proceeds under the arch of the aorta to
the left lung.
  Each of the bronchi  is subdivided  where it enters the
lung;  the  right separating  into three principal  branches,
corresponding to the number of the lobes on that side  ; the
left into only two, which are distributed to the same num-
ber of lobes of  the lungs on the left side.   When the bron-
chi have arrived in the lungs, they  divide and  subdivide
throughout the whole  pulmonary tissue, ramifying almost
ad infinitum, so that it is extremely difficult to trace them
to their termination.  Malpighi thought that they ended in
rounded membranous vesicles.   Senec describes the lobu-
les of the lungs to be composed of polyhedral vesicles, into
each of which a twig of the  bronchi  enters.  If a lung be
inflated and  dried, its substance when divided, independ-
ently of the arteries cut through, appears uniformly porous.
Some of the pores appear sections of tubes, others are small
cups, being  sections of air-cells, a hundredth of an  inch
in diameter.*

  *After injection, a thin section of the lung may be made, and submitted
to the microscope, when it will be found that the size of the areola?,  in the
adult, is nearly as here stated ; and the shape of the areolae appears to me,
to be, as stated by Senec, polyhedral. 
ORGANS OF RESPIRATION.
217
  THE ORGANIZATION OF THE  TRACHEA AND  BRONCHI.

  The air tubes of the lungs are composed of fibro-cartila-
ginous,  incomplete rings,  membranous  mucous follicles,
bronchial glands, vessels and nerves.
  The fibro-cartilaginous rings in  the  tra-
chea, Fig. 66, are from sixteen  to twenty in
number ; they are not complete behind, but
united  by  a fibrous  membrane, which is
closely connected with the  oesophagus, and
yields  to  it  in the  time of deglutition.  Each cartilage
forms nearly two  thirds of a  circle, as in     Fig 67
Fig. 67, a, a ; they are situated transversely
with respect  to  the length of  the  trachea,
and have their edges opposed to each other,
leaving small spaces between them.   These
spaces consist of the same fibrous membrane
which completes  the canal at  the posterior  part:  it has
great elasticity, so that when the lungs are removed from
the body, it draws the fibro-cartilages together.
  At the superior part of  the  trachea  the cartilages  are
sometimes  united, but  below  they are  perfectly distinct
from each other;  and the inferior cartilage  is triangular, to
adapt itself to the bifurcation of the bronchi.
  In the bronchi, the  primary ramifications are similar to
those of the trachea, only thinner and smaller, and some-
times composed of several  pieces.   But  in the  secondary
and ultimate  ramifications, they are merely small irregular
tubes, which  gradually  diminish until they arrive  at  the
areolae of the lungs.
  The outer membrane is formed of longitudinal and paral-
lel fibres, of which the  most superficial is  red, the deeper
white.  This membrane alone, posteriorly, connects the car-
tilages, and completes the diameter of the trachea.   Ante-
  vol.  n.              28 
218
ORGANS OF RESPIRATION.
riorly,  the  fibro-cartilages  appear developed  in its sub-
stance.
  Posteriorly, this membrane  contains  numerous mucous
follicles, the excretory ducts of which open on its inner sur-
face.   They are named the glands of the trachea.
  The mucous membrane is a continuation of the membrane
of the  larynx, and extends to the termination of the bron-
chi ;  the mucous follicles constantly pour out a thick fluid
on its inner surface.
  The lymphatic glands of the bronchi, are situated at the
bifurcation  of the trachea, around the bronchi, and are
found  even in  the interior of the lungs.  Their color is
blackish ; they are easily compressed  under the fingers, to
which they easily communicate their  color.   Their  excre-
tory ducts  have not been  discovered, and their functions
also are unknown. 
ART.   XI.
ORGANS OF THE VOICE.
THE LARYNX.
  The larynx is  a complicated apparatus situated at the
upper part of the trachea, with which  cavity it communi-
cates ; it is  immediately under the  os hyoides which is
placed at the root of the tongue.   It is broader above than
below, and is composed of several cartilages, muscles, liga-
ments, membranes, and mucous glands.

          THE CARTILAGES OF THE LARYNX.
THYROID CARTILAGE.
The thyroid cartilage, Fig. 68, is  the largest and most
prominent of the pieces  com-
posing the larynx, and occupies
its anterior and lateral parts :
in its natural situation it forms
two lateral wings, or portions
of a quadrangular form, uniting
in the middle in a longitudinal
angle,  which  can  readily  be
felt in  the  fore part of  the
throat; and  from  its  being
Fig. 68.
 
220
ORGANS OF THE VOICE.
larger and  more  projecting in men than  in  women, has
obtained the name of pomum Adami.   The upper part of
the angle is  formed into a notch, from which, and  from
the upper edge of the cartilage in general, a broad  liga-
ment ascends to unite it to  the inferior part of the os
hyoides.
  From  the  posterior angles  we  observe  four  projecting
processes called cornua, two of which a, a, are termed the
superior cornua, and are connected by round ligaments to
the os hyoides.  The other two, b, b, are called the  infe-
rior cornua ;  these are shorter than the superior, and some-
what moved  backwards, to be attached by smooth  articu-
lating surfaces to  the sides of the cricoid cartilage.


                  CRICOID CARTILAGE.

  The cricoid cartilage is placed  below the thyroid, and
like it can readily be felt  in the fore part of the neck.  It
is  narrow anteriorly, see  Fig. 69 ; and  thick,  broad, and
strong, posteriorly, see Fig. 70: its  superior edge  has its

          Fig. 69.                         Fig. 70.
anterior part fixed to the thyroid cartilage ;  the  inferior
edge is connected to the whole circumference  of the com-
mencement of the trachea.
  This cartilage has four small  articulating surfaces, with
distinct capsular ligaments ;  two of which  are situated at
 
ORGANS OF THE VOICE.
221
its upper part, for the articulation of the arytenoid  carti-
lages, and two at the under part, for the attachment of the
inferior cornua of the thyroid cartilage.


                ARYTENOID  CARTILAGES.

   The arytenoid cartilages (Fig. 71, the outer, and Fig. 72,
the inner view), are two in number ;  they are situated at

         Fig. 71.                           Fig. 72.
the upper and back part of the larynx, above  the cricoid
cartilage.  Their form is before us ;  the anterior surface is
convex, but  upon each convexity  there  is a  depression,
which  is occupied  by glands.  Their  upper  extremities
are placed towards each other: their lower extremities are
broad,  and  are  articulated  by capsular  ligaments  with
the cricoid  cartilage, upon which  they are  moved by the
action  of various muscles.  They are also connected  to
each other, and to the adjacent cartilages, by ligaments and
muscles.
  The aperture between  the  arytenoid cartilages is called
the glottis.
 
222
ORGANS OF THE VOICE.
                      EPIGLOTTIS.

  The epiglottis (Fig. 73, the outer, and Fig. 74, the inner
view), has obtained its name from  its situation above the
Fig. 74.
glottis : it is a fibro-cartilage, situated at  the  upper part
of the larynx, behind the base of the tongue;  its form is
ovoid, its color a pale yellow, and  its tissue very elastic.
It is  placed obliquely over  the  glottis, and  may be  seen
and  examined in the living body  by pressing down  the
tongue.
  This cartilage is  attached by a  broad and  short  liga-
ment to the notch of the  thyroid  cartilage ; laterally it is
united to the arytenoid cartilages, forming at this part the
superior opening of the larynx.  It  is  united to the  os
hyoides  and tongue by a ligament which is termed  the
franum epiglottidis.
  The surface is  covered by a number of small perforations
and depressions, which contain mucous follicles, or transmit
nervous filaments.
Fig. 73.
 
ORGANS OF THE VOICE.
223
            THE  LIGAMENTS  OF THE  LARYNX.

  The ihyro-hyoid articulation.  The thyroid cartilage is
connected at its upper part with the os hyoides by a broad
yellowish membrane.   The superior cornua of this cartilage
is connected to the extremities  of that bone by two round,
fibrous cords, about an inch in length.
  The crico-thyroid  articulation.  The  thyroid cartilage,
in the middle and anteriorly,  is connected with the cricoid,
by the crico-thyroid membrane,  and on the  sides, the infe-
rior cornua of the thyroid cartilage are articulated with the
cricoid cartilage, by means of a loose and  humid synovial
membrane.  There are also two ligaments  extending from
the inferior cornua of the thyroid cartilage to the arytenoid
cartilages where they are expanded.
  The crico-arytenoid articulation.   Each arytenoid car-
tilage is  articulated  with the  cricoid, by a synovial cap-
sule, which is  strengthened by fasciculi of  ligamentous
fibres.
  The vocal ligaments, or the thyro-arytenoid articulation.
On the inside  of the  larynx we observe  two  ligaments,
Fig.  75, a, about two lines  in
breadth, formed of  elastic and
parallel fibres,  contained  in a
fold of the mucous membrane;
they  are  extended  horizontally
from the anterior  prominence of
the  arytenoid cartilage,  to the
centre  of the  retiring angle of
the thyroid cartilage.  They are
named the vocal cords.
 
224
ORGANS OF THE VOICE.
            THE MUSCLES OF THE LARYNX.


                   CRICO-THYROIDEUS.

  This muscle, Fig. 76, a, a, is situated on the side and
at the anterior and inferior  part of the  larynx;  it  ex-
Fig. 76.
tends from  the lateral and  anterior  edge of the  cricoid
cartilage, to  the  lateral and inferior  edge of the thyroid
cartilage.
  The office of this muscle  is  to depress and  draw  for-
ward the thyroid  cartilage,  or  to raise  the cricoid car-
tilage. 
ORGANS OF THE VOICE.
225
          CRICO-ARYTENOIDEUS  POSTICUS.


This muscle, Fig. 77, b, is extended from the back part
Fig. 77.
of the base of the arytenoid cartilage, to the posterior part
of the cricoid cartilage.
   Its office is to draw back the arytenoid cartilage.
VOL. II.
29 
226
ORGANS OF THE VOICE.
          CRICO-ARYTENOIDEUS LATERALIS.

This muscle, Fig. 78, c, is extended from the lateral and
Fig. 78.
inferior part of the arytenoid cartilage, to the lateral part
of the cricoid cartilage.
   Its office is to separate the arytenoid cartilages, and with
them the glottis.


                  THYRO-ARYTENOIDEUS.

   This muscle, e, extends from the fore  part of the aryte-
noid cartilage to  the inferior and  posterior part of the thy-
roid cartilage.
   Its office is to draw the arytenoid cartilage outwards and
forwards, and thereby to enlarge the glottis, and to shorten
and relax the  vocal cords.
   A small fasciculus of this muscle, on its  upper part, is
called by Albinus thyro-arytenoideus alter minor. 
ORGANS OF THE VOICE.
227
                    ARYTENOIDEUS.

  This is a single muscle, Fig. 77,/,  situated at the supe-
rior and posterior part of the larynx ; it is formed of several
planes of fibres, which have occasioned it to be divided by
many anatomists  into several  distinct muscles.  It is at-
tached to the posterior part of each of the arytenoid carti-
lages, from  whence  the fibres take  different  directions;
some extend from the  base of the right cartilage to the
summit of the left, others take an inverse course, and some
pass horizontally from the middle  part of one to the same
point of the other.
  The office of this muscle is to close the glottis, by draw-
ing the  arytenoid  cartilages  together;  at  the same  time
they bring the vocal cords in nearer apposition.
         MUCOUS MEMBRANE  OF THE  LARYNX.

  This membrane is continuous superiorly with the mucous
membrane of the mouth ; inferiorly, with  that of the tra-
chea and bronchial tubes;  posteriorly,  with  that of  the
pharynx.  Its tissue is very firm, but yet highly vascular,
and it contains in its substance a number of mucous folli-
cles, the orifices  of which are easily perceived.  It secretes
a somewhat  tenacious fluid,  which keeps its inner surface
in a moist state.
            THE  GLAND  OF THE EPIGLOTTIS.

  This gland  consists of  small  granulations,  deeply  im-
mersed in a quantity of adipose cellular  tissue, and  occu-
pying a triangular space at the lower part of the anterior 
228
ORGANS OF THE VOICE.
surface of the epiglottis.   It pours its secretion upon  the
laryngeal  surface of the epiglottis.


                THE ARYTENOID  GLANDS.

  These glands are situated in the folds which the mucous
membrane presents in passing from  the epiglottis to the
arytenoid  cartilages, and from these to the thyroid cartilage.
They are composed of small granulations resembling those
of the lachrymal gland.
  There is  much difficulty in discovering  their excretory
orifices.
              THE OFFICE  OF THE  LARYNX.

  All the modifications of the voice  are  produced  by the
air passing from the lungs through the larynx ; sounds may
also be produced  by it in  the time  that air traverses the
larynx to pass into the trachea, but  these  tones  are  pro-
duced with more difficulty, and are not according to the
ordinary laws of economy.  If we blow air into the trachea
towards the larynx, at the same time  bringing the arytenoid
cartilages  together, a sound  will be produced something
like the voice of the animal, to which  the larynx used in
the experiment belongs.
  The sound will be dull or sharp according as  the carti-
lages  are pressed, more or less  forcibly, together,  and its
intensity will be according to the force of the current of
the air.  We may observe, in this  experiment,  that  the
sound is produced by the vibrations  of the vocal  cords.
  The strength of the voice  depends upon the  extent of
the vibrations of the vocal  cords, and these will be in  pro-
portion to the force with which the air is expelled from the 
ORGANS OF THE VOICE.
229
chest.  The  tone of the voice generally agrees with the
state of the cartilages of the larynx.
  We can, therefore, account for the production of voice
on physical principles.  I will  transcribe the explanation
given by Magendie.   " The air being  pressed  from the
lungs, proceeds  in  a pipe of considerable size; this pipe
very soon becomes contracted, and the air is forced to pass
through  a very narrow slit, the two  sides  of  which are
vibrating  plates, which permit  and  intercept the air, like
the plates of reeds, and in the same manner, by these alter-
nations,  produce sonorous  undulations  in the transmitted
current of air."


                 THE  THYROID  GLAND.

   This body, Fig.  79, covers
the lower and  anterior part of
the  larynx, and the first  two
or three  cartilages of the  tra-
chea: it  is composed  of  two
lobes, generally united  in a
great part of their extent; but
 frequently they  are unconnected, except  by  a  sort  of
 transverse cord.
   The structure of the thyroid  body  is  soft  and spongy ;
 most commonly it is of a brownish  red  color, and is com-
 posed of a number of distinct lobules.   An oily or a milky
 fluid may be pressed from its areolae, but it is an organ re-
 specting the office of which we are  totally ignorant, and
 which anatomists usually describe  after  the larynx, merely
 on account of its situation.
 
ART.   XII.
ORGANS OF SECRETION.
ORGANS  FOR  THE  SECRETION AND  TRANSMISSION OF  THE
                        TEARS.

  These organs consist of the lachrymal glands, the puncta
lachrymalia, the lachrymal ducts, the caruncula, the lachry-
mal sacs, and the nasal canals.


                THE  LACHRYMAL GLAND.

  This gland, Fig. 80, a,
is situated in a depression
of the frontal bone, at the
upper, outer and fore part
of the orbit.  It is about
the size of a small  al-
mond, but  the  form is
various, most commonly
it  is  a  flattened ovoid.
Its color is  light yellow,
inclining to red.
  The lachrymal gland is
formed of a considerable
Fig. 80.
 
                 ORGANS OF SECRETION.             231

number of lobules, connected  by cellular tissue, and these
lobules are  composed of granulations, the intimate struc-
ture of which  is  still  entirely unknown.  It  is supposed
that from each of them issues a small excretory tube, which
unites with  others in its  vicinity, and forms  trunks more
distinct.   It appears that there are six or seven in number,
b, and that  they open on the inner surface of the eyelid.
   A  fibro-cellular  capsule  of  considerable  thickness en-
velopes the lachrymal gland.


             THE CARUNCULA  LACHRYMAL1S.

   The caruncula  lachrymalis, e, is a small red tubercle, sit-
uated in  the inner angle of the eyelids: it consists of a
mass of mucous  crypts  or follicles, covered by  the  con-
junctiva, and forming, on its  outer side, a fold* which al-
lows of the motion of the globe of the eye.   Each orifice
of the crypts is furnished with hairs of excessive  delicacy,
and visible  only with a lens.


                THE PUNCTA LACHRYMALIA.

   The puncta  lachrymalia are  two in number,  one for each
eyelid ; they occupy the centre of a small tubercle at c, c,
these are the orifices of the lachrymal ducts, which convey
the tears into,/, the lachrymal sac.

   * This folding of the conjunctiva is  termed by anatomical writers, the
remains of the membrana nictitans: such a name, however, is quite absurd,
as it has no such office, structure, or muscular apparatus, as that membrane.
The use of this fold is simply to permit of the turning of the eye outwards:
for that purpose there is a similar lax fold at the opposite angle, and at the
connexion of the superior and the inferior palpebrse with the globe of the
eye.  If these foldings of the conjunctiva did not exist, the eye would be
fixed, and it would be impossible that  the eye  could be revolved in any
direction. 
232
ORGANS OF SECRETION.
                 THE  LACHRYMAL SAC.

  The lachrymal sac, f is a small membranous bag, situa-
ted in a groove of the os unguis, and ascending process of
the upper maxillary bone.  It receives the lachrymal ducts,
and is continued into the nasal duct.
                   THE NASAL DUCT.

  This canal, g, is continued from  the  lachrymal sac, and
opens, at h, into the nasal fossa, beneath the inferior turbi-
nated bone, by an orifice provided with a circular fold of
the pituitary membrane.  This canal is lined by a continu-
ation of the mucous membrane of the lachrymal sac.
  The nasal duct conveys the  tears  into the nose, which
the puncta lachrymalia have absorbed.


                 THE SALIVARY GLANDS.

  There are three salivary glands situated behind and be-
low the lower jaw.  They do  not  receive vessels at a de-
terminate point, but are penetrated on all sides by adjacent
vessels which ramify in their texture.  They are surround-
ed by a layer of cellular tissue, and  have excretory ducts
which open into the mouth. 
ORGANS OF SECRETION.            233
Fig. 81.
1. THE PAROTID GLAND.
  The parotid gland, Fig. 81, a, is situated in the recess
which exists on the side of the face, between the  posterior
border of the lower jaw and the ear, and extends from the
zygomatic arch as far as the angle  of the inferior maxilla.
  This gland is of a grayish white color, and is composed of
granulations united into lobules and lobes by condensed cel-
lular tissue.   These granulations  give origin to excretory
ducts,  which,  uniting, form b, the duct  of Steno, which
proceeds over  the  masseter  muscle, and,  perforating the
buccinator  muscle, opens into the mouth, on a level with
  vol. n.              30 
234            ORGANS OF SECRETION.
the second superior molar  tooth.*  The duct is formed of
two membranes ;  one exterior, white,  thick and resistant;
the other interior, a mucous membrane.
   We find in the substance of the  parotid  gland  a great
number of branches of the facial nerve, the transverse ar-
tery of the face, the posterior auricular artery, and the vein
which  forms a communication between  the external and the
internal jugular vein.


               2. THE SUBMAXILLARY GLAND.

   This gland, Fig. 81, c, is situated on  the inner side of the
ramus  of the lower jaw, between the  two  portions of the
digastric muscle.    Its structure  is similar  to  that of the
parotid.
   Its excretory duct is commonly named Wharton's duct;
it is much smaller  than  the parotid duct, and commences
by minute roots in the  granular substance of the gland,
passes  horizontally between the genio-glossus and  the sub-
lingual gland, until it reaches the side of the fraenum of the
tongue, where it opens by a narrow orifice placed on the
centre  of a small tubercle.


                3.  THE SUBLINGUAL GLAND.

   This gland is situated under  the fore  part of the tongue ;
it is smaller than the submaxillary gland, and nearly of the
shape of an almond ;  il; is covered by the  mucous mem-
brane of the mouth, beneath which it forms a prominence.
It   has several very  slender excretory  ducts :   six  or
eight  proceed  from its  upper part to open upon the sides

 "The duct of the parotid may be exposed by cutting in the direction of a
line drawn from the lobe of the ear to the anterior openings of the nares. 
ORGANS OF SECRETION.
235
of the fraenum linguale, while  five or six others issue from
the lateral parts, and  perforate  singly the mucous mem-
brane of the inferior part of the  mouth.   Two or three of
these may be seen terminating in the submaxillary duct.
  The organization is similar to the other salivary glands.
  The saliva which these glands  secrete  flows constantly
into the mouth, and mixes with the fluids  produced by the
membranes  and  mucous follicles.  This  liquid has been
analyzed by Berzelius, and found to contain :  water 939;
a particular animal matter 29 ; mucus 1*4 ; muriate of soda
and potass 0-7 ;  tartarite of soda and  animal  matter  0*9 ;
soda 0-2.  The  composition of the saliva is known to be
variable, for in some instances it  is sensibly acid.
   The saliva is one of the  most  useful digestive fluids ; it
is favorable to mastication and division of the food; it as-
sists in  deglutition, and the conversion of  the  aliment
into chyme ; it also renders more easy the  motion of the
tongue in speech and in singing.   The greatest portion of
the fluid is carried into the  stomach by the  motion of de-
glutition ; another portion must  evaporate and go out of
the mouth with the expired air.


                     the pancreas.

   The pancreas,  Fig. 82, is a gland  situated  transversely
 in the abdomen,  behind the stomach.  Its form is irregular

                          Fig. 82.
 
236
ORGANS OF SECRETION.
 and very variable;  its weight is  from three to six ounces.
 Its  anterior surface  is  covered  by the transverse  meso-
 colon, the stomach, and the first  portion of the duodenum.
 Its posterior surface presents, at  its  upper  part, a groove
 which contains the  splenic vessels.  There is very frequent-
 ly  beneath  it a small detached  glandular mass,  of the
 same structure, named the small pancreas.
   The pancreas bears an exact resemblance to the salivary
 glands in its structure:  its color is light red, and from  its
 lobules we can  trace the radicles of its excretory duct,
 which, progressively increasing in size, proceeds in  a ser-
 pentine form  towards the duodenum, where  it is as large
 as a crow-quill.   Near its termination it receives the ex-
 cretory duct from the small pancreas, and after a short pas-
 sage, the common pancreatic duct opens into  the ductus
 communis  choledochus ;  or rather adheres to it as it enters
 the duodenum at the  same point.
   The pancreatic fluid, I believe, has never  been collected
 in sufficient quantity to be analyzed ; but it is generally con-
 sidered to  be analagous to saliva.  Its office,  therefore, is
 merely conjectural; and  it is  only known  that this  fluid
 mingles with the  bile and is poured into the  duodenum.


 ORGANS  FOR THE  SECRETION  AND  TRANSMISSION OF
                       THE BILE.

                      THE LIVER.

  The liver is the largest of all  the  glands ; it entirely
 occupies  the right  hypochondrium, and that  part of the
epigastric region  which  is beneath the  diaphragm  and
above the  stomach, the  lesser  omentum, the  duodenum,
 the arch of the  colon,  the gall  bladder,  and  the  right
 kidney: it is placed in front of the aorta and inferior vena 
ORGANS OF SECRETION.
237
cava, and behind the anterior parietes of the abdomen.  It
is very dense, its weight, in the adult, varying from two to
five  pounds.  It is convex on  the superior  surface and
irregularly concave on  the inferior surface.  It is divided
into three lobes.
  1.  The great lobe is situated obliquely in the right hypo-
chondriac region ; it corresponds with the curve of the di-
aphragm, and rests upon the pylorus, colon, and superior
extremity of the right kidney.
  2.  The small lobe is partially separated from the greater
by a broad ligament, and is situated almost horizontally in
the epigastric region ; only a small part  extending to the
left hypochondriac region.
  3.  The  lobulus spigelii  is situated  on the left side of
the great lobe, and is of a pyramidal form, projecting  be-
tween the cardia and vena cava,  at  the  small curvature of
the stomach.  Two prolongations* appear to connect  its
base to the great lobe of the liver;  one of these gradually
loses  itself at its surface ; the other ascends posteriorly to-
wards the groove of  the inferior vena cava, and contributes
to its formation.
  The liver has several depressions  and  fissures, namely :
  The fissura umbilicalis, or the groove  of  the umbilical
vein,  situated between  the large and small  lobes, at  the
under and fore part of the liver, which, in the foetus, con-
tains  the umbilical vein ;  and in the adult it is occupied by
the fibrous cords which are formed by the remains of these
obliterated vessels.
  The sinus port arum, or groove  of the inferior vena cava,
is situated behind, near the convex edge of the liver: it is
short but deep, and often exists as a true canal.  The porta
receives the great blood vessels, and the nerves  which pass

  * These parts of the liver are frequently described as the lobulus caudatus,
and the lobulus anonymus, or quadratus. 
238
ORGANS OF SECRETION.
 into the liver, and the  biliary ducts and  absorbents which
 proceed from it.


               LIGAMENTS OF THE LIVER.

   The  liver is retained in its position by folds of the peri-
 tonaeum, termed the ligaments: —
   1. The ligamentum  latum, which is  united  to  the  dia-
 phragm and the  tip of  the ensiform cartilage, and then de-
 scends in  an  oblique direction, adhering to the  inner edge
 of the vagina of the rectus abdominis of the right side as
 far as the  umbilicus.
   2. The ligamentum rotundum, which was the umbilical
 vein in  the foetus, is placed in a duplicature of the ligamen-
 tum latum, and united to the umbilicus.
  3. The ligamentum coronarium, unites the root or poste-
 rior part of the liver to the  tendinous  portion of the  dia-
 phragm.
  4. The ligamentum  dextrum, or  right lateral ligament,
 connects the  posterior part of the great lobe of the liver to
 the diaphragm.
   5. The ligamentum  sinistrum,  or left  lateral ligament,
 connects  the small lobe to the  diaphragm.    The  two
 lateral ligaments are merely the extension of the coronary
 ligament.
   Haller has described  two  other  ligaments,  the  one
 connecting the gall bladder and the contiguous sinus por-
 tarum to the  colon, called  the hepato-colic ligament; the
 other termed  the hepato-renal, which unites the liver to the
kidney. 
ORGANS OF SECRETION.
239
               ENVELOPES OF THE LIVER.

  The peritonaal envelope is reflected from the lower sur-
face of the diaphragm over the liver, and gives it externally
its shining appearance.
  The cellular envelope covers  all the parts of the liver,
and is extended into its substance, forming  sheaths  which
accompany the branches and twigs of the vena portae, the
hepatic artery, and hepatic duct.   These sheaths have been
designated the capsule of Glisson.
  The interior substance of the liver is of a reddish brown,
or yellowish color.   Its general aspect is porous ; this, how-
ever,  arises from  the great number of small  vessels which
are divided in cutting it.  If the tissue of the liver is torn
instead of being cut, it  then appears composed of an im-
mense quantity of granulations, in which the extreme ram-
ifications of the blood vessels and biliary ducts terminate.
The most minute researches have disclosed nothing  further
with respect to its intimate structure.


                  THE  HEPATIC DUCT.

  The hepatic duct commences by a great number of very
slender radicles in  the granulations of the liver; these
radicles,  termed  pori  biliarii,  unite  successively  into
branches, accompanied  by the divisions of the vena  portae
and hepatic artery, and form two principal trunks, one from
the left lobe,  the other from the right;  these  proceed out-
wards, and, uniting at a right angle, form the hepatic duct.
This duct is about an inch and a half in length, and a line
and a half in diameter ; it ascends  between  the two folds
of the gastro-hepatic omentum, before the vena portae, on
the left of the  neck of  the gall  bladder, and unites with
the cystic duct. 
240
ORGANS OF SECRETION
                  THE GALL BLADDER.

  The gall bladder is a membranous reservoir, situated in
a superficial depression of the inferior surface of the right
lobe of the  liver.  It is  composed of  three  membranes.
1st.  A serous membrane, which is  the peritonaeal covering
on  the lower surface.  2d. A cellular  membrane, which
unites  the serous to the inner  membrane.   3d. A mucous
membrane of considerable thickness, which lines the interi-
or, and has  a peculiar honey-comb  appearance.  At  the
neck of the gall bladder this membrane forms several folds,
which, from their arrangement, have  been called the spiral
valve.

                     CYSTIC DUCT.

  This duct, which is situated in the gastro-hepatic omen-
tum, forms a continuation with the neck of the gall blad-
der, of about one inch and a half in length; it is in appo-
sition with  the hepatic duct for a short distance, and after-
wards  unites with it, forming the  ductus communis choledo-
chus, or the common canal  for the  transit of the bile.
         THE  DUCTUS  COMMUNIS CHOLEDOCHUS.

  This  duct is  formed by the junction of the cystic and
hepatic.  It is from three  to four inches in length, and  is
situated between the two folds of the gastro-hepatic omen-
tum.  It opens with the pancreatic duct obliquely, into the
duodenum near its last curve. 
ORGANS OF SECRETION.
241
Fig. 83.
  Fig. 83, a, the gall bladder,  b,  the  cystic duct, c, the
principal branches of, d, the hepatic duct;  these unite
and  form,  e, the ductus communis  choledochus,  which
terminates at, A, by an aperture in the inner surface of the
duodenum.
                  SECRETION OF BILE.

  The circulation in the liver is very remarkable, from its
receiving  blood from  two sources ; the  hepatic  arteries,
and from the department of veins continued from the vena
portae, which are distributed after the manner of an artery
throughout the substance of the liver.  There  is another
department of veins for returning the blood, consisting of
the venae cavae hepaticae, which open into the inferior cava.
Fluids injected into the hepatic artery, or into the vena
portae, readily pass into the venae cavae  hepaticae,  and
into the hepatic ducts.   We may  infer from this  that
  vol. n.              31 
242
ORGANS OF SECRETION.
both venous and arterial blood  may serve for the secretion
of bile.
  The bile appears to be the most  complex of all the ani-
mal fluids.  Professor Mayo states  that, besides a number
of saline ingredients,  it contains  mucus,  albumen,  osma-
zome,  gliadine, casein, picromel, asparagin,  acetic  acid,
oleic acid,  margaric acid,  cholic acid, resin  and  coloring
matter.
  The bile contributes very essentially in the digestive and
assimulative  processes, but in  what manner  is  unknown.
Persons commonly attribute noxious properties to the bile,
which  it is probably far  from possessing.


                      THE  SPLEEN.

  The spleen is situated in              Fis- 84.
the posterior part of the left
hypochondrium, beneath the
diaphragm, behind the  de-
scending colon, and imme-
diately over the left kidney.
Fig.  84,  shows  its form ;
its weight cannot  be  pre-
cisely stated, as it  presents
the most numerous varia-
tions.
  It is attached to the sur-
rounding organs  in a loose
manner by folds of the pe-
ritonaeum, and by  a great number of vessels.
  The spleen is single, but I have  several times  found a
supernumerary spleen adjacent to it.
  The outer surface is convex ; the inner is divided by a
 
ORGANS OF SECRETION.            243
groove called the fissure of the spleen, which  is filled by
vessels and a certain quantity of fat.


             ORGANIZATION  OF  THE SPLEEN.

  It is of a spongy consistence : it always contains a very
large proportion of blood, which  seems identified  with its
tissue, and which is found not only in its vessels, but also
in the very numerous cellules and areolae of which this
organ is chiefly formed.  It contains also a number of soft
grayish, semitransparent granulations, disseminated irregu-
larly in its tissue.   Malphighi considers them small glands,
but their nature is quite unknown.
   Sometimes two or more small bodies, of the same color
and  structure of the spleen, are found in its vicinity, be-
tween the laminae of the omentum.
               OFFICE OF THE SPLEEN.

  Regarding the  office of the spleen, there  has  been a
number of speculations; I shall only refer to some of the
most plausible, and those which  meet with the most gen-
eral support.  Dr. Haighton advanced it as  his opinion,
that the spleen was subservient to digestion, by occasioning
an increased secretion of the gastric and pancreatic fluids,
at the precise time when they are  most required.  In ex-
plaining the mode in which  this effect is to be produced,
he agreed with Haller in the opinion, that the stomach,
when distended with  food, makes sufficient pressure  on
the spleen, to prevent the ordinary supply of its cells, and
to direct  the blood, commonly sent  to it, to  the stomach
itself, and to the pancreas.
  It  is suggested by Sir Astley  Cooper,  that it is a part 
244
ORGANS OF SECRETION.
of the function of the  spleen  to  elaborate venous blood,
and thus assist the liver in the formation of bile.
  Sir C. Bell also regards it " as a provision for giving
the vessels of the  stomach an occasional power and greater
activity, enabling them to pour out a quantity of fluid pro-
portioned to the necessity of digestion."
  My talented and  indefatigable friend, Dr. Hodgkin, has
devoted much attention to this subject, and from consider-
ing the  situation  and structure of the spleen — the differ-
ent appearances  which it assumes, according to the  cir-
cumstances  under  which  death has  taken  place — the
causes which derange it, and the effects which it produces
on the system when deranged — together with the result of
experiments  made  on inferior animals — he has been in-
duced to adopt a very different opinion :  he believes, " that
the spleen performs, in the  animal system, a similar office
to that which tubes  and valves  of safety do in various chem-
ical and mechanical apparatuses."   By this comparison he
(Dr. Hodgkin) would wish it to be understood ; " that the
spleen tends  to  obviate any inconvenience which might
arise from a sudden disturbance of the proportion between
the capacity of the  vascular system, and the  fluids which
circulate in  it.   These  disturbances,"  he adds, " must, I
conceive, be  frequently induced  by  various causes  to
which  the  animal  system  is continually exposed, and
which  operate more  powerfully than the elasticity of the
vessels alone can compensate for, and  more readily  than
absorption,  secretion,  and  excretion can,  in  every case,
counteract." 
ORGANS OF SECRETION.
245
               SUPRA-RENAL  capsules.

                          The supra-renal capsules, Fig.
                        85, are two small bodies, situated
                        above the kidneys ;  they are of a
                        light brown color, and  consist of
                        a small bag, the exterior of which
                        is granulated  and collected into
                        lobules.  In  its interior  we  ob-
serve  a narrow,  smooth, triangular  cavity, without any
known orifice :  it is furnished in  its inferior  part with a
prominent ridge, and it contains, in the foetus, a consider-
able  quantity of  a reddish viscid albuminous  fluid.   In
after life this fluid is of a deeper color
  The office of these capsules has hitherto eluded research ;
their volume is much greater in the foetus than in the adult.
On this account it is supposed  that they have  some  con-
nection with the exercise of nutrition in the first stages of
life, or that these  organs are useful in the foetal state, by
deriving the blood from the kidneys, those glands not then
having undertaken their proper  functions  of secreting
urine.
                     THE KIDNEYS.

  The kidneys are two glandular bodies, situated  in  the
lumbar regions, on the sides of the vertebral column, op-
posite the two last dorsal  and the  two first lumbar verte-
brae.  The right kidney is placed at the under and back
part of the large lobe of  the  liver, and is usually a little
lower than the left kidney ; the latter is placed  under  the
back  part of the spleen, and  behind  the left  portions of
the stomach, pancreas, and colon.
 
246
ORGANS OF SECRETION.
   The kidney is four or five inches in length, and in shape,
as we may see in the following figures, resembles the kid-
ney bean which is named from it.
   It is totally imbedded  in  a very solid and more or less
thick mass of fat.   This adipose  tunic is extended likewise
to the renal vessels, and  is  supposed to defend them from
the pressure of the surrounding viscera.
   The right kidney is connected to the liver, the left to
the spleen, and both  to the muscles  on which  they are
placed,  and to the supra-renal glands and colon by cellular
tissue :  the peritonaeum is reflected from  the liver and the
spleen to the kidneys.


             ORGANIZATION OF  THE  KIDNEYS.

   The surface of the kidney is usually smooth and uniform,
though  sometimes  it is  irregular, in consequence of the
lobes which originally form it not being so completely in-
corporated.  Each kidney  receives from  the  aorta an
artery of considerable diameter, and returns its blood by a
large  vein into  the inferior vena cava.  A very distinct
nervous  plexus  surrounds these vessels, and the lympha-
tics are  very easily  to be traced.
   The  kidney appears  to be formed of two distinct sub-
stances ; an external or  cortical, and an internal tubular,
or medullary substance.
   The cortical substance of the kidneys forms the external
layer of these organs, and internally it is prolonged into
them  in the form  of septa,  between which we  find the
conical fasciculi of  the tubular substance.   When viewed
with a microscope, the cortical substance appears composed
of solid  granulations of a very small size, formed by the
capillary extremities of the renal arteries and veins.
   The tubular substance presents  a number of  conical fas- 
ORGANS OF SECRETION.
247
ciculi, surrounded on all sides, except at their summits, by
the cortical substance.   The base of each cone is directed
towards the circumference of the kidney, and their summits,
on the contrary, are directed towards  the  pelvis, or fissure
of the kidney.
  The color of this substance is a  pale red ; its tissue is
dense and is formed of a multitude of very minute  conver-
gent canals, termed tubuli uriniferi, which derive their ori-
gin from the cortical substance, and terminating in larger
ducts at the summits of the cones, present so many mam-
millae,*  at the points of which the  urine oozes out.  The
number of mammillae is twelve or fourteen ; the orifices of
the canals (called the ducts of Belini) of the tubular sub-
stance are less  numerous than the canals themselves, on
which account it is to  be presumed that several of these
uriniferous tubes unite before they terminate.


          THE CALYCES, PELVIS, AND URETER.

   The calyces, or infundibula, are membranous tubes which
embrace the mammillae, and which receive the urine from
them.  The infundibula are commonly the same  in num-
ber as the mammillae ;  the  number, however, varies in dif-
ferent subjects, two or more mammillae sometimes  opening
into the same infundibulum.
   The pelvis is a membranous bag formed by the union of
the infundibula; it is contracted at the inferior part to be
continued into the ureter.
   The ureters,  or  the  excretory ducts of the  kidneys  are
long membranous canals, of a cylindrical  form, and about
the size of a writing quill; each extends from  the  pelvis of
the kidney, with which it is  continuous, to the fundus of
the bladder into which it opens.
* Frequently termed papilla:. 
248
ORGANS OF SECRETION.
  The uterers descend in  the loins obliquely inwards be-
hind the peritonaeum, and over the psoas and iliac muscles,
and, passing into the pelvis, terminate in the under, outer,
and back part of the bladder, by a narrow oblique orifice.
  The infundibula, pelvis and ureters appear  to have the
same organization ;  being composed of two  membranes,
namely, an outer, thick, white, opaque membrane,  which
may be considered  as a prolongation of the fibrous capsule
of the kidney ; and  an inner, mucous, transparent  mem-
brane, which is  extended from  the  infundibula  over the
mammillae,  and perhaps even introduced  into the urinife-
rous tubes.
  Where the ureters open into the bladder, some few  pale
muscular fibres  may  in general  be  found.  These have
been  named  the muscles  of the ureters, by Sir Charles
Bell, who describes each as arising  from the vesical ex-
tremity of the ureter, and  thence descending obliquely for-
wards and inwards, to be inserted by a tendon common to
its fellow into the tubercle  or uvula of the  urethra.   The
use which he assigns to them is, to restrain the termination
of the ureters, and preserve the obliquity of the passage of
these tubes through the  coats of the bladder when it is
contracted ; for  without  this provision, he remarks, the
urine would be sent retrograde into the ureters, instead of
forward into the urethra. 
ORGANS OF SECRETION.
249
Fig. 86.
Fig. 86, exhibits a section of the kidney.
a, the cortical substance.
b, the tubular substance.
c, the mammillae, around which are the infundibula.
d, the pelvis.
e, the ureter.
/, the renal artery.
g, the renal vein.
VOL. II.
32 
250
ORGANS OF SECRETION.
                     THE BLADDER.

  The  urinary bladder is  a musculo-membranous reser-
voir, whose office it is to retain for some  time  the urine
which is afterwards to be ejected  from it.  The bladder
is situated in the  pelvis at  the bottom of the hypogastric
region.
  The  superior  part of the bladder is in contact with the
inferior  convolutions of the small intestine ;  and from  its
centre  we observe a fibrous  cord termed  the urachus,
which ascends between the linea alba and the peritonaeum
to the  umbilicus, where it  terminates in  the abdominal
aponeurosis.
  The inferior part or fundus of the bladder, in  the male,
is connected by cellular tissue  to  the vesiculae seminales,
and the end of the vasa deferentia.  That portion of the
bladder, which is between the two  vesiculae, rests upon the
rectum.  In the female the bladder is connected with the
levator ani and the vagina.
  The anterior part is situated behind the pubes, but when
the organ  is  distended by urine, we find  it in  the hypo-
gastric  region.    Their is  a fasciculus of  fibrous  mem-
brane which attaches the anterior part of the bladder to the
symphysis of the  pubes, named the  anterior ligament of the
bladder.
  The posterior part is entirely covered by the peritonaeum,
and is contiguous, in the male, to the rectum, and in the
female,  to the uterus.
  The  internal  surface  of the bladder  is  formed by a
mucous membrane, which,  in  its   empty state,  presents
numerous irregular rugae, but  these disappear when the
bladder is full;  and we always find on the  fundus a re-
markable triangular space where the mucous membrane  is 
ORGANS OF SECRETION.
251
 destitute of rugae; it is named the trigonal  space of the
 bladder.
   The neck of the bladder has a  crescent-like  form, the
 margin  of  which  is very thick, and it embraces a small
 tubercle, designated by the name of the uvula vesica.


         THE  ORGANIZATION  OF THE  BLADDER.

   The peritonaal  membrane is reflected  over  part of the
 superior, posterior and lateral  portions  of the bladder, and
 it is united to  the  muscular  membrane  by loose cellular
 tissue.
   The  muscular  membrane consists of  muscular fibres,
 spread  out  in  various  directions over the bladder;  the
 greater  number,  however,  are  longitudinal, a few only
 being transverse.   These fibres are stronger  on  the  an-
 terior and posterior surfaces than on the sides.   On  the
 latter region they run  obliquely.   The anterior fibres,
 from having a fixed attachment, are called by some anato-
 mists the detrusor urina  muscle.
   The neck  of the  bladder is  formed of a  firm, white,
 extensile, fibrous  membrane, with  muscular fibres, having
 the same arrangement as on the bladder itself; this is gen-
 erally designated by anatomists as the sphincter vesicae.  J.
 Cloqjjet  altogether denies that it is a sphincter  muscle,
 and states it to  be  merely the  fleshy fibres brought closer
 together than elsewhere.
   The cellular membrane is  that which connects together
 the mucous and  muscular  structure of the bladder,  and
in  which  we  observe  the  most  numerous  vessels  and
 nerves.
   The  mucous  membrane  is  continuous  with the inner
surface of the ureters and the  urethra.   Its villosities are 
252
ORGANS OF SECRETION.
very delicate and not  easily detected :  in its natural state
no mucous follicles are to be observed, but in certain mor-
bid conditions their presence is very apparent.


    THE OFFICE  OF THE KIDNEYS  AND  THE BLADDER.

  The  kidneys  separate the urine from  the blood, and
convey it by means of the ureters to the bladder.  There
is  every reason  to  suppose that  substances hurtful  to
the  animal economy  are discharged  in  this fluid;  for
when there is a total suppression of  this  secretion, or
when the  renal  arteries are tied, death occurs in a short
space of time.
   When the  pelvis of a kidney is cut open, in the  liv-
ing  animal, the  urine  may be seen to pass out slowly
at the  points of  the  excretory cones.   Or if we remove
the  kidney from the  body, and  compress  the urinife-
rous cones, we  observe a considerable quantity of  this
fluid issuing from them.  The urine then enters  the pelvis
of the  kidney, and by small  quantities  proceeds through
the  ureter  by a  constant  exudation, and slowly distends
the bladder.  The urine is  prevented  from flowing back
into the ureters, by these conduits  passing a  consider-
able distance into the  sides of the bladder, so that, in
proportion  as the urine distends this organ, it compresses
the ureters, and closes them more  firmly as it is more
abundant.   This mechanism may be observed  in   the
dead body, for if we inject the  bladder  with water or
even air, by the  urethra, we find that it never enters  the
ureters. 
ORGANS OF SECRETION.
253
                      THE URINE.

  There  is no  fluid of the human  body so variable with
respect to quantity and  quality; for it varies according
to age,  to the  quantity of  fluids  drank,  the  nature of
the aliments or medicines taken, or according to the sea-
son of the year: in the winter  it  is more copious, and in
the summer, from  the increased  transpiration, it is more
sparing and high colored.   Affections of the mind also
influence the secretion; thus fright  makes the urine pale
and copious.
   The numerous researches made concerning urine have
given the following as its component parts:  1  water;  2
urea; 3  phosphoric  acid; 4, 5, 6, 7, phosphates of lime,
magnesia, soda, and ammonia;  8, 9,10, 11,  lithic, rosacic,
benzoic, and carbonic acid; 12  carbonate of lime ;  13,14,
muriates  of soda and ammonia ; 15 gelatin ; 16 albumen ;
17 resin ; 18 sulphur.*
* Dr. Ure. 
254
ORGANS OF SECRETION.
  According to Bebzelius the  following are the ingredi-
ents of 1000 parts of healthy urine.

       Water,.........93300
       Urea,..........30-10
       Sulphate of potass,.....    3*71
       Sulphate of soda,......3*16
       Phosphate of soda,.....    2-94
       Muriate of soda,......4*45
       Phosphate of ammonia,  ....    1*65
       Muriate of ammonia,.....1*50
       Free lactic acid— lactate of ammonia
         — animal matter  soluble in  alco-
         hol — urea not separable  from the
         preceding,.......17*14
       Earthy   phosphate, with a  trace of
         fluate of lime,......1-00
       Uric acid,........     1-00
       Mucus of the bladder,.....0-32
       Silex,.........    0-03
1000-00 
ART.   XIII.
        ORGANS OF GENERATION IN THE MALE.

  These consist of the testicles and their appendages, the
vesiculae  seminales, the prostate, the ductus  ejaculatorii,
and the penis.


       THE TESTICLES AND THEIR APPENDAGES.

            1. THE ENVELOPES OF THE TESTICLES.

  1st.  The scrotum, or the cutaneous envelope of the tes-
ticles, is a continuation of the skin of the  adjacent  parts.
It is remarkable  for having a deeper color than other parts
of the skin, for the great number of mucous follicles  which
it contains in its substance, and  for its long and scattered
hairs which are inserted obliquely, and so superficially that
their bulbs produce distinct elevations of the skin.   Upon
the surface of the  scrotum there is a superficial, longitudi-
nal, elevated  line,  called the raphe, which divides it into
two equal parts,  and extends as  far as the anterior part of
the anus. 
256    ORGANS OF GENERATION IN THE MALE.

   2d.  The dartos is a filamentous cellular membrane of a
rose color,  entirely  destitute of  adipose substance,  in
which an infinite number of  vessels  are  distributed; and
although  some  authors  have described it as a muscle, it
certainly does not exhibit the smallest appearance of mus-
cular fibres.   It is  attached  to  the  ischium and  pubes;
meeting in the middle that of the opposite side, thus form-
ing a septum which  separates the  testicles.   The inner sur-
face is applied to the fibrous tunic of these organs, and on
the extremity  of the cremaster muscle; the outer  surface
adheres to the scrotum.
   3d.  The cremaster muscle.  This has been  already de-
scribed.   See Vol.  I. page 213, Fig. 131.
   4th.  The fibrous  tunic is  thin, transparent and very
little resistant;  it forms  an  elongated sac, placed  within
each dartos.   Superiorly, it forms  a sheath for the sper-
matic cord, and, inferiorly, it contains the testicle and epi-
didymis.
   5th. The tunica   vaginalis, a serous membrane   which
constitutes, like  all  other serous membranes, a sac without
an opening;  it  covers  the  whole  internal surface of the
fibrous tunic, and is  extended to the epididymis and tes-
ticle ; entirely covering the latter  excepting at its upper
edge.   In infancy it is manifestly  continuous with the peri-
tonaeum, having  descended with it into the scrotum.  This
circumstance  explains  the  formation of  that  species of
hernia in which  the intestine is in immediate contact with
the testicle.


                    2. THE TESTICLES.

   The testicles are  two ovoid  glandular organs, lodged in
the scrotum.   The  right testicle is generally a little  higher
than the left. 
        ORGANS OF GENERATION IN THE MALE.    257


            ORGANIZATION  OF THE TESTICLE.

  The tunica albuginea is a fibrous membrane, white and
opaque, not unlike the sclerotica;  it serves as a direct en-
velope to the testicle.  Its outer surface is covered  by the
serous membrane ; its  inner is applied upon the  proper
substance of the testicle, and sends into the interior of it
a number of delicate prolongations, directed  towards its
posterior part.  These septa divide the testicle into  several
cells which contain  the seminal vessels.
  On  the  inner side of this membrane  we  observe the
corpus Highmorianum, an  elongated prominence  at the
superior  part of the  testicle, across which the principal
trunks of the seminal vessels pass  obliquely towards the
epididymis.
  The parenchyma  of the  testicle  is  soft, of a gray color
marbled  with red, and is formed of an immense number
of very minute  tortuous  tubes, slightly connected  to each
other. According to the observations of Monro, they do
not exceed the two  hundredth  part of an inch in  diame-
ter ; these  tubes, termed vasa  seminalia, or tubuli semini-
feri,  do  not ramify, but their  length  is  very great; the
same author estimates their  number at about  sixty two
thousand  five  hundred, and  he  considers  their total
length to  be  five  thousand two  hundred feet: capillary
arteries and veins of still greater minuteness  are observed
among them.
  The seminal ducts just described are all directed towards
the superior part of the testicle,  where  they form from
twenty to  thirty considerable trunks, which traverse the
corpus Highmorianum, opposite and a little below the epi-
didymis,  where they  dilate and  give  origin  to the duct
which forms the epididymis.
  vol. n.             33 
258    ORGANS OF GENERATION IN THE MALE


                     3.  EPIDIDYMIS.

  This name is given to  the canal formed by the union of
all  those  smaller tubes, which compose  the  body of the
testes and the corpus Highmorianum.  The epididymis is
situated upon the upper  part of the testicle, is inclosed in
the same covering with it, and is exceedingly convoluted
until  it  passes  into  the spermatic  cord.   Its superior
part arises from the  corresponding  part of the  testicle,
where it receives the vasa efferentia; its inferior part is
adherent to  the testicle, and is  continuous with the vas
deferens; its middle portion is adherent to the testicle.


                     4. VAS DEFERENS.

  The vas deferens is the large excretory duct of the testi-
cle.   It commences at  the lower part of the  epididymis,
ascends, describing many flexuosities, behind  the testicle,
and immediately enters the spermatic cord, where it is pla-
ced behind, and internally to the  artery and nerves which
accompany it.   After passing the ring it leaves  the other
vessels of the cord, and descends  backwards and inwards
upon  the side of the  bladder.  Then, arriving under the
inferior  and posterior region of the bladder, it  approaches
its fellow, and proceeds along the inner edge  of the vesi-
culae seminales.   At  the base of  the  prostate gland, it re-
ceives a canal from  the vesiculae seminales, and is continued
into the ejaculatory duct.
  The vas deferens is slender near its origin, but on pass-
ing through  the abdominal ring  it  increases in  size, and
becomes twice  as  large along the vesiculae seminales : at
its termination, however, it resumes its original size.  The
parietes of this duct are very thick, and have  almost a 
        ORGANS OF GENERATION IN THE MALE.    259

cartilaginous consistence ; its cavity is so small as scarcely
to admit a hair, except near the vesiculae, where it is much
larger.


                   5. SPERMATIC C011D.

  The spermatic cord is composed of the last mentioned
duct, namely, the  vas  deferens, the  spermatic artery and
vein, of some other  inconsiderable  and irregular blood
vessels, lymphatics, and   nerves.   It  is   enveloped by
several membranous  layers, and  contains  a  large quan-
tity of cellular  tissue in the intervals  of  its component
parts.  It  ascends from the upper  part of  the  testicle,
and  enters into  the abdomen  by the inguinal ring.   The
organs of which it is  composed then separate from each
other, and follow a course with which we are already ac-
quainted. 
260    ORGANS OF GENERATION IN THE MALE.


  Fig. 87.   Posterior  view of
the testis and  tunica  vagina-
lis.
  a, the spermatic cord.
  b, the vas deferens.
  c, the commencement of the
epididymis.
  d, the testis  devoid  of the
tunica vaginalis.
  e, the tunica vaginalis.
THE VESICULAE SEMINALES, PROSTATE, COWPER'S GLANDS,
              AND DUCTUS  EJACULATORH.

                 1. VESICULAE SEMINALES.

  The vesiculae seminales  are situated beneath  the blad-
der, in front of the insertion of the ureters, and on the
outer  side of  the vas deferens.   They are two membra-
nous reservoirs about two  inches and a half in length, and
six  or seven lines in breadth.  In  dried preparations the
vesiculae appear as a  cavity composed of numerous cells;
but if they are carefully dissected  they present a flexuous
canal.
Fig. 87.
 
        ORGANS OF GENERATION IN THE MALE.    261

  These vesiculae are  filled with  a thick yellowish fluid,
which has been supposed to have retrograded from the vasa
deferentia; but as, in some animals, the vesiculae seminales
have no connection with the excretory ducts of the testes,
we may reasonably infer that they are not mere receptacles
of the secretion of the testicles.   The vesiculae  are organs
of secretion, producing a peculiar fluid which is ejected at
the same moment as the secretion just mentioned.


                   2. PROSTATE GLAND.

  The prostate gland is a body of the  size and  figure of a
chesnut, formed of an assemblage of mucous follicles sur-
rounding the neck of the bladder and  the commencement
of the male urethra.
  This gland has a division forming it into two lateral lobes,
and there is sometimes an inferior lobe at the base of the
prostate, first noticed by Morgagni, and  subsequently very
particularly described by Sir Everard Home.   It is called
lobus Morgagni.
   The upper surface is covered by the inferior ligament of
the bladder;  the lower surface rests upon the rectum.  Its
base forms a very remarkable prominence round the neck
of the bladder ;  its summit terminates upon the membra-
nous portion of  the urethra.
   The prostate gland is of a light gray color, and its struc-
ture is very dense and firm ; it is filled with a great number
of small follicles containing a viscid fluid.  From  these
follicles ten or fifteen excretory ducts  arise and open into
the urethra, on  the sides  and at the  surface of the Veru-
montanum.  When we remove this  gland  from  the dead
body and compress it, the fluid it contains is made to issue
from the orifices of these  ducts. 
262    ORGANS OF GENERATION IN THE MALE.


                  3. COWPER'S GLANDS.

  These are two small granulated glandular bodies, placed
parallel to each other before the prostate.  They are of a
red color,  about the  size of  a pea,  and of a  structure
resembling the salivary glands.  Each of these glands has
an excretory duct, which proceeds obliquely  inwards  and
forwards in the spongy tissue of the urethra, and opens
before the Verumontanum.  These glands are for the pur-
pose of secreting a mucus, to be discharged into  the urin-
ary passage.


                  4.  EJACULATORY DUCTS.

  These ducts commence at an acute angle, formed by the
junction of the vasa deferentia with those which  terminate
the vesiculas seminales ; they are about an inch in length,
and proceed parallel to each other, in the substance of the
prostate gland, opening into the urethra by two  small ob-
long orifices, situated upon the lateral and  anterior part of
the Verumontanum. 
ORGANS OF GENERATION IN THE MALE.     263



                 Fig. 88.
  Fig. 88,  exhibits the urinary bladder  inflated, and  the
principal parts of the organs of generation of the male.
  a, the peritonaeum covering the bladder.
  b, the muscular membrane of the bladder.
  c, the corpus cavernosum penis.
  d, the corpus spongiosum urethrae.
  e, the bulb of the urethra.
  /, one of Cowper's glands.
  g, the  prostate  gland  surrounding the neck  of  the
bladder.
  k, the inferior lobe of the prostate gland.
  i, i, the vesiculae seminales.
  I, I, the testes. 
264    ORGANS OF GENERATION IN THE MALE.
   m, m, vas deferens.
   n, the membranous portion of the urethra.
   o, the right crus of the penis.
  p, the ureter terminating in the bladder.


                         PENIS.

  The penis  is  formed  by the corpus  cavernosum,  the
urethra, the corpus spongiosum urethra, terminated by the
glans; the vessels, nerves, and a cutaneous investment, which,
by its prolongation, forms the prepuce.


         1. INTEGUMENTS OF THE PENIS AND PREPUCE.

  These parts  are merely a  continuation of the  common
integuments, which are here  more  delicately thin, and in-
stead of fat, there is, as in the scrotum, only a cellular
tissue.
  At the anterior extremity of the  penis  the integuments
form  a  greater or less prolongation, which is  termed the
prepuce, which covers  the glans when the  penis is in a
state of relaxation.   The prepuce is connected to the un-
der part of the glans by a triangular fold, termed  the fra-
num preputii.
  The prepuce is composed of two membranous  layers,
between  which is a plane cellular tissue ;  the outer layer is
formed by the skin ;  the inner is  of  the nature of a mucous
membrane, and is furnished with sebaceous  follicles, term-
ed the glandula odorifira.


                 2.  CORPUS CAVERNOSUM.

  Most writers on  anatomy describe two corpora  caver-
nosa penis, but there exists only one; there are certainly two 
        ORGANS OF GENERATION IN THE MALE     265

roots, and a septum in  part of its extent, but it is  so in-
complete a partition, that, with Cloqjjet, Chaussier and
others, we must consider it as a single body.
  The corpus cavernosum forms about  two-thirds of the
volume of the penis : it is placed over the urethra, and ex-
tends from the anterior and inner part of the sciatic tuber-
osity, as far as the substance of the glans.
  The roots of the corpus cavernosum are  attached to the
inner border of the ramus of  the ischium and pubes ;  they
are about  two inches  in  length, commencing  in front of
the sciatic tuberosity, and uniting at the inferior part of
the symphysis pubis.   The  triangular space which  sepa-
rates them from each other, is occupied  by fat and  by the
urethra.
  The anterior extremity of the corpus  cavernosum is
united to the base of the glans, and  perforated by several
apertures for the passage of vessels.   Its upper  surface is
marked with'  a longitudinal  groove, in which we observe
the dorsal  artery and  veins  of  the  penis.   Posteriorly it
gives attachment to the suspensory ligament of this organ,
being a fibrous fasciculus attached to the inferior part of
the symphysis pubis.   The inferior surface is marked by a
broad, deep groove, which receives the superior side of the
canal of the urethra, to which it  adheres by a filamentous
cellular tissue.
      ORGANIZATION OF  THE CORPUS CAVERNOSUM.

  The corpus cavernosum is composed of  a very strong
fibrous tunic, of an opaque white appearance, excepting at
its roots and  at  the anterior extremity, where its color is
more or less livid.   Its fibres are for the  most part longi-
tudinal, and are interwoven posteriorly with the periosteum
  vol. n.             34 
266     ORGANS OF GENERATION IN THE MALL

of the bones of the ilium, and the aponeurosis of the mus-
cles, which are attached to their lower edge.
  The cavity of this fibrous membrane is partially divided
into two lateral portions, but the  partition does not extend
beyond two thirds of its length ; it is then continued merely
as a few fibrous fasciculi to the glans.
  The spongy tissue,  enveloped by the preceding  mem-
brane, appears to  consist of a complicated net-work of arte-
rial  and venous  vessels,  probably of nerves  also, and of
small fibrous laminae, which latter form numerous cellules
communicating with each other, and with the blood vessels,
and always containing a greater or less quantity of blood.
An  injection made by the cavernous artery passes into
these cellules, and if, on the contrary, we inflate these
cellules with  air, it passes  into  the cavernous vein, so that
we may conclude that they are intermediate with the arte-
ries and veins.


                      3, URETHRA.

  The urethra extends from the neck of the bladder to
the extremity of the glans penis ; its capacity very much
exceeds  that  of  any  other excretory duct.   Its parietes
are partly  spongy and partly  membranous.  At  first  its
course is directed a little  forwards and downwards ; next
traversing the prostate gland, it passes through a  circular
aperture of  the  triangular  ligament of the bladder, and
under the symphysis pubis mounts in front of it  between
the two roots of the corpus cavernosum, and then descends
in the groove, in the superior surface of the latter as far as
the summit of the glans penis, where it opens by a vertically
elongated orifice.   It is distinguished into three portions:
  1st. The prostatic   portion,  which  is  from  fifteen  to
eighteen lines in length, and passes  obliquely through the
prostate  gland. 
        ORGANS OF GENERATION IN THE MALE.    267

  2d. The membranous portion is thin and contracted;  it
is from eight to ten lines in length, and united to the rec-
tum inferiorly and posteriorly, and anteriorly approaching
the inferior part of the symphysis pubes.
  3d. The spongy portion commences posteriorly by the
bulb of the urethra, which is situated beneath the angle  of
union of the roots of the corpus cavernosum.  Anteriorly
it expands to form the glans penis.
  The cavity of the urethra has not the same dimensions
through its whole extent; it is  rather broad at its origin ;
it contracts and again dilates in the centre of the prostate
gland.  The membranous portion  is much narrower than
any other part of the  canal, and in its  spongy portion its
breadth is very nearly equal except towards  its extremity,
where there is a remarkable dilation, termed  the fossa na-
vicularis.
   The interior of the  urethra, through the whole length
of the canal, presents two white lines, the one superior, the
other inferior; the latter line  terminates posteriorly in a
prominence, about an inch long, named the verumontanum,
or the  caput gallinaginis, continuous  posteriorly with a
small fold of the mucous membrane: the orifices of  the
ejaculatory ducts open at its sides ; those of the prostate on
its surface, and those of Cowper's glands in front of it.


            ORGANIZATION  OF  THE URETHRA.

   The mucous lining of the urethra is continuous at  the
one extremity with  that  which covers  the  glans, and at
the other, with the mucous membrane of the bladder.   Its
color  is a bright red near its orifice, but it  becomes pale
and white through the remainder of its extent.  A great
number of small foramina are observed opening on its sur-
face, named sinuses of  Morgagni : and by a folding  of the 
268    ORGANS OF GENERATION IN THE MALE.
membrane they form so many lacunae, commencing at the
bulb and becoming more numerous towards the fossa navi-
cularis.
  The spongy tissue  surrounds the three anterior fourths
of the length of the urethra ; it is somewhat  thick at the
bulb, then becomes contracted into a cylindrical tube as far
as the glans penis ; this spongy tissue being expanded so
as to form this part.
  The membranous portion of the urethra is braced to the
arch of the  pubes by muscular  fibres, discovered by Mr
Wilson, and named by him the compressor urethra : when
this muscle acts it compresses the urethra so as to close it
as completely as a sphincter, while, from  its attachments,
it draws the urethra towards the pubes.
                     GLANS  PENIS.

  The glans is covered by a very delicate  epidermis ;  and
is circumscribed by a prominent  ridge, called the corona
glandis.   Its internal tissue has the same characteristics as
the corpus cavernosum, only appearing more dense.
  Fig. 89, exhibits a section
of the penis.
  a, a, the corpus  caverno-
sum penis.
  b, the  corpus  spongiosum
urethrae.
  c, the urethra.
 
ART.   XIV.
ORGANS OF  GENERATION, AND FOR THE NUTRITION OF
             THE CHILD, IN THE FEMALE.


  The genital organs of the female consist of the vulva,
the vagina, and  the uterus, and its appendages.
  The vulva, or pudendum, is the name given to the ex-
ternal parts of generation in  the  female, under  which are
comprehended —
  1st.  The labia pudendi, two  membranous  folds, formed
by a  prolongation  of the skin, beneath  which there are a
considerable number of sebaceous follicles.  The integu-
ment on the fore  part of the symphysis  pubis is slightly
elevated  by  a quantity  of cellular and  adipose substance
deposited beneath it, and is covered with hair.  This part,
from its surmounting the labia, has been called Mons Ven-
eris.    The  inner surface  of the labia is a red  mucous
membrane, continuous with the  other  parts of the vulva.
The  intervening substance, that is, between  the  skin and
the mucous membrane, consists of adipose tissue and some
fibres of the constrictor vaginae muscle.  The  labia unite
both  beneath the mons,  and before the  perinaeum,  the
points of union  being  called  commissures.  The inferior
one  has also received  the name  of fourchettc, and the in- 
270         ORGANS OF GENERATION, &c.
terval between this  and the entrance of the  vagina  has
been called fossa navicularis.
  2d. The clitoris,  a small elongated tubercle, placed at
the middle and superior part of the vulva: it is  supposed
to bear some analogy to the penis of the male, in having a
sort of glans surrounded by a  fold of the mucous  mem-
brane similar to the prepuce.  It has also  a corpus  caver-
nosum, of a spongy texture, adherent  by two roots  to the
rami of the ischia;  it receives a great quantity of nerves.
  3d. The nympha are two membranous crescent-like folds,
extending from the prepuce of the clitoris to the  middle of
the orifice of the vagina ; each of the nymphae is  formed of
two laminae of the mucous membrane of the vulva; they
contain also in their substance a small quantity of spongy
erectile tissue.
  4th. The urethra is only an  inch in  length;  it is wide
at its commencement, and descends obliquely  forwards,
terminating at  the  superior part of  the entrance  of the
vagina, by an orifice called the meatus urinarius:  in its
course it describes a slight curve, the concavity of  which
is turned upwards.  It is lined by a vascular mucous mem-
brane, and contains a great number of mucous lacunae.
  5th. The orifice of the vagina  commences beneath the
meatus urinarius; it is  occupied by the hymen,  or  by the
caruncula myrtiformes.
  The hymen is considered as one of the surest signs of
virginity ; it consists of a more or  less distinct fold  of the
mucous membrane  of the vulva; at the entrance  of the
vagina;  its form is semilunar, consequently not completely
closing the opening.
  The caruncula myrtiformes are small red tubercles, exist-
ing only after the rupture of the hymen ; they are  in  fact
the remains of the lacerated hymen.
  The vagina is situated in the pelvis, between the bladder
and the rectum, and extends from the vulva to the neck of 
IN THE FEMALE.
271
the uterus.  It is from six to eight inches long, somewhat
curved, its concavity being next to the bladder, therefore
shorter before than behind, and somewhat more contracted
at its extremes  than in the middle part:  its position is
nearly vertical, or rather directed a little downwards and
forwards.
   The outer surface is invested superiorly, to a small extent,
by the peritonaeum;  inferiorly it is contiguous  with and
between  the bladder and  rectum, being connected with
these parts by a dense cellular tissue.   On the sides it cor-
responds above to the broad ligaments of the uterus, and
below to a mass of cellular  tissue which  separates it from
the levatores ani muscles.
   The internal  surface is  covered by the  mucous  mem-
brane, and presents  numerous transverse wrinkles termed
ruga, which are less distinct on the  sides, and are most
prominent inferiorly ; near the uterus the rugae follow every
variety of direction.   There are also two longitudinal ridges
formed by the mucous membrane, and intersecting the for-
mer at right angles.


             ORGANIZATION OF  THE VAGINA.

   The mucous  membrane is continuous  with  that of the
 vulva and the uterus.   Between the  rugae  it is perforated
 by a multitude of orifices of mucous follicles.
   The erectile spongy tissue forms around the inferior part
 of the vagina, a layer  about  an inch broad, and  two or
three lines thick: it is described by De  Graaf under the
 name of retiformis, and by later anatomists under  that of
 the corpus cavernosum vagina.   Superiorly it becomes very
 thin, but it may be traced as far  as the uterus, and  seems
 to be continuous with the proper tissue of that organ. 
 272         ORGANS OF GENERATION, &c.


            THE UTERUS AND ITS APPENDAGES.

   The uterus, or womb, is situated  in  the middle of  the
 pelvis, between the bladder and rectum, above the vagina,
 with which it is intimately connected, and beneath the in-
 ferior  convolutions  of the small intestine.  Its  figure is
 annexed.  It is flattened from  before  backwards and is
 nearly an  inch  in thickness.  Superiorly it is about two
 inches broad, but it is contracted  inferiorly towards  the
 vagina, and terminates by a narrow portion called the neck,
 to distinguish it from the  other part of the organ, which is
 called  its body.  The fundus is  the broad part which pro-
jects above the attachments of the  Fallopian tubes, sur-
 mounting the body.   It presents a convex border, and is
 covered by peritonaeum in its entire extent.
  The body of the uterus is  about two inches in length;
 its surfaces are convex, and invested with the peritonaeum ;
 its anterior part is in contact with the bladder, its posterior
 with the rectum.  The cervix,  or neck of the  uterus, is
 about fourteen lines in length, its transverse diameter from
 eight to ten.  Its  upper part is embraced by  the vagina;
 the orifice  of the uterus, called  the  os  tinea, projects into
 the superior part of that canal.
  The cavity of the uterus is small in  proportion to  the
 volume of the organ.   It is triangular and compressed ; its
 edges are curved, and  its upper angles present the extremi-
 ties of the  minute openings of the Fallopian tubes.  Each
 of its surfaces are traversed by a longitudinal slightly ele-
 vated line.   The cavity of the cervix is  nearly cylindrical,
and  somewhat dilated  before it terminates in  the vagina.
 It presents a continuation of the vertical lines  I have just
 mentioned, and  some faint rugae taking a transverse direc-
 tion. 
IN THE FEMALE
273
Fig. 90.
  Fig. 90, exhibits a section of the unimpregnated uterus,
in which we observe the relative size of its cavity and the
thickness of its parietes.
  a, fundus uteri.
  b, os tincae.
  c, c, a section of the uterine extremities of the Fallopian
tubes.
            ORGANIZATION  OF THE UTERUS.

  The serous membrane is a  covering formed by the peri-
tonaeum, which adheres firmly to its upper edge, but upon
the two surfaces it is separated  from the proper  tissue of
this organ by a quantity of cellular tissue  and blood  ves-
sels.   In uniting with  the  lateral borders,  it  forms two
angles, at the middle  part of which the  Fallopian  tubes
terminate, above the insertion of the ligament of the ovary
  vol. n.              35 
274          ORGANS OF GENERATION. &c

which  is posteriorly, and of that of the  round ligament
which is anteriorly.
  The mucous membrane is  similar to  that of the  vagina.
It is covered with  fine  villosities, and,  towards the neck,
presents very numerous orifices of mucous crypts, some of
which assume the form of transparent vesicles.
  The proper  tissue of the uterus is  dense, elastic, and
traversed by a great number of blood vessels.   Although it
is impossible to describe the exact disposition of its fibres,
as its  structure is  inextricable  in the ordinary state, yet
I entertain no doubt of its muscularity.  In its impregna-
ted  state, or immediately  after  parturition, its muscular
fibres are very apparent in dissection.  Sir C. Bell has
stated that the fibres of one order, which cover the upper
segment of  the gravid  uterus, arise  from  the   round
ligaments,  and, regularly  diverging,  spread   themselves
over the fundus, until  they unite  and form  the exterior
stratum of the proper tissue  of the uterus. On the
outer surface and lateral parts, other muscular fibres have
an  appearance  of   irregularity   among the larger blood
vessels; but  they  are  so disposed  that they are well
calculated  to  compress the vessels, whenever  the  uterus
is  excited  to  contraction.   Those who  have  the  oppor-
tunity of examining the gravid  uterus in its recent state,
will  feel convinced, that it  is  distinctly and  powerfully
muscular;  but the  course of the interior fibres  are less
easily described than we might  imagine.  This is owing
to the intricate interweaving of the fibres with each other;
an intertexture, however,  which  gradually increases  the
extent  of  their power  in  diminishing the cavity  of  the
uterus.   After making  sections  of the substance  of  the
womb  in  different  directions, says the eminent anatomist
just  mentioned, "  I  have no  hesitation in saying  that,
towards the  fundus, the circular fibres  prevail ; that, to-
wards the  orifice, the. longitudinal fibres  are  most appa 
IN THE FEMALE.
275
rent; and that, on  the whole, the  general  course of the
muscular fasciculi is from the fundus towards the orifice."
This prevalence of longitudinal fibres is undoubtedly a pro-
vision for diminishing the length of the uterus, by drawing
one extreme towards the other.   At the  same time, such
an  arrangement of the fibres, by their action, must dilate
the orifice.
  The inner surface of the fundus  consists of two sets of
fibres, running in concentric circles round  the orifices of
the Fallopian tubes : these circles, at  their circumference,
unite and produce  an intricate tissue.  There  are other
strata of fibres commencing at the centre of the last mus-
cular fasciculi,  and, having a course at first circular, then
descend in broad irregular bands towards the orifice of the
uterus.
   The arteries of the  uterus are derived from  the  sper-
matic and hypogastric ; their principal branches are very
 flexuous,  and unite frequently together beneath  the peri-
 tonaeum.   Its veins follow the  same  course, but are still
 more tortuous, and form cavities in  its parietes, which be-
 come so large, during gestation, as  to obtain the term of
 uterine sinuses.
   When  the uterus is contracted, the blood vessels are
 invisible,  but,  during  pregnancy, they are so large and
 distinct, that  the orifices of some of  them,  when divided,
 will admit the  end of  the little finger.  This fact, then, of
 the natural closing of the vessels by uterine contraction,
 leads us to contemplate this  organ as  admirably  construct-
 ed for the reception of the ovum, the growth of  the foetus,
 and  the  expulsion of the  placenta without dangerous
 haemorrhage. 
276         ORGANS OF GENERATION, Ac.
                 THE  BROAD  LIGAMENTS.

   The broad ligaments* are two folds of the peritonaeum;
they form, with  the uterus  and  the upper  part of the
vagina,  a transverse septum, which  divides the cavity of
the pelvis into two parts.   These ligaments are continuous
by the inner edge,  with the peritonaeum which invests the
two  surfaces of the uterus, and are externally expanded
upon the sides of the excavation of the  pelvis.  They are
formed of two  peritonaeal laminae, the  interval of which
contains cellular tissue ;  and  superiorly on each side, the
Fallopian tubes; beneath and anteriorly, the round  liga-
ments ;  and posteriorly, the ovaries.   The tubes occupy the
free edge of the ligament; the  other two organs raise its
surface and form two smaller foldings.


                THE ROUND  LIGAMENTS.

   The round ligaments are two  long and  slender cords,
commencing immediately  before and  below the Fallopian
tubes, near the angles of the uterus, from which they de-
scend in the broad  ligaments, and, diminishing a  little in
their course, direct themselves towards the internal ingui-
nal ring, pass through it, and terminate by expanding in
the cellular tissue of the pudendum.
   Their structure is dense and fibrous, with an interposed
cellular tissue and an evident vascularity.


          THE FALLOPIAN, OR UTERINE  TUBES.

   The Fallopian tubes, formerly very well named  the ovi-
* Ligamcnta lata, termed sometimes ulic vcspcrtilionis. 
IN THE FEMALE.
277
ducts, are two canals placed at the superior edge, and in the
duplicature of the broad ligaments.  They are about  four
or five inches in length, and extended from the upper an-
gles of  the  cavity  of the  uterus,  to  near  the side of the
upper diameter of the pelvis.  In  the inward half of their
length they are small and straight; afterwards these tubes
become larger and more flexuous,  and terminate in  a wide
floating fringed extremity, called fimbria.
   The cavities  of the  Fallopian tubes  are very small, in-
deed  scarcely admitting the  entrance of  a bristle;  they
gradually become larger as they  approach the  sides  of the
pelvis;  near their  outer extremity they are  considerably
dilated, but are afterwards suddenly contracted, and  ter-
minate  by an opening of sufficient size to admit the point
of a writing quill.
   These tubes are lined by a very  thin mucous membrane,
of a florid  color, slightly villous,  and presenting  several
longitudinal plicae.   No mucous follicles have hitherto been
discovered in them.
   Externally, these organs are formed by a layer of  spongy
and erectile  tissue, similar to that of the  urethra,  and, as
before noticed, invested by the peritonaeum.


                     THE OVARIES.

   The ovaries, anciently termed testes  muiiebres, are  two
compressed oval bodies placed in the  substance  of the
broad ligament; they are of a pale red  color, and some-
what irregular at their  surface.  Their outer extremity is
attached to one of the fimbriae of the Fallopian tubes ; the
inner is connected  to  the uterus by a  small  filamentous
cord, about an inch and a  half long, called the ligament of
the ovary.
   Each ovary is enveloped in a  dense cellular membrane. 
278         ORGANS OF GENERATION, &c.

which is prolonged into the parenchyma of the organ, the
texture of which is composed of a loose  and spongy sub-
stance.  When minutely examined  we  perceive cellular
and vascular lobules, of a gray color, filled with fluid.   In
the midst of these  lobules we find from  fifteen to twenty
transparent small vesicles, called ova; these are formed by
a very delicate membrane filled with  an albuminous fluid.
  The ova differ in the same ovarium from the size of a
mustard seed to that of a pea, and the largest are com-
monly situated nearest the surface.
  In the prime of life the ovaria are large and uniform at
their surface ; but in females advanced in life they become
small, unequal, and irregularly formed ; and in those who
have borne many children a similar irregularity is apparent.
  The ovaria are intended for the nourishment of the ova,
which contain the embryo or rudiments of the  foetus. 
IN THE FEMALE.
279
Fig. 91.
  Fig. 91, exhibits the vagina, the  uterus, and its  appen-
dages.
  a, the  vagina cut open, shewing on its inner surface the
rugae and carunculae.
  b, the uterus.
  c, c, the broad ligaments.
  d, d, the round ligaments.
  e, e, the Fallopian tubes.
  /,/ the external opening of those tubes with their fim-
briae.
  g, g, the ovaria. 
280         ORGANS OF GENERATION, Jkc.
                 THE GRAVID UTERUS.

  When the ovum has been conveyed through the Fallopian
tube, from its  receptacle, into the cavity of the uterus,
conception has taken  place.   Do the rudiments of  the
foetus proceed from  the  male or  from the female ?  We
may pass over the theories of the ancients and moderns on
generation ; at  best they are but " brilliant reveries which
overload the mind of the student, and do more injury than
is  generally supposed to the  progress  of science."*   All
that physiologists have  discovered, as  it regards fecunda-
tion, is, that the part of the male, in the act of reproduc-
tion, is to deposit the semen in the vagina at a greater or
less distance from the orifice of the uterus.   The function
which the female discharges is more obscure.  The uterus,
at impregnation, is supposed  to attract the  semen and di-
rect it to the  ovarium by means of one of the Fallopian
tubes, whose fimbriated extremity closely embraces that
organ.
  The contact of the semen occasions  the rupture and de-
livery of one of the  ova, and the fluid that passes from it,
or  the ovum  itself passes into the uterus, where the new
individual is to  be developed.
  The time which intervenes between the instant of fecun-
dation and the delivery of the child, is called uterogestation,
or  pregnancy;   it is generally  nine calendar  months or
forty weeks.
  When the  ovum has arrived in the cavity of the uterus,
it closely unites with the interior of this organ ; here it re-
ceives the materials necessary for its growth, and acquires,
by degrees, a considerable volume: the uterus yields to this
augmentation, and consequently, changes its form  and po-
sition.
* Markndie. 
IN THE FEMALE.
281
  During the first three months of pregnancy, the develope-
ment of the uterus is  inconsiderable, and  takes place in
the hollow of the pelvis ;  but, in the  fourth, as the  organ
becomes  larger, this cavity will no  longer contain it,  and it
rises into the hypogastrium.   The uterus continues to in-
crease in all directions until  the eighth month, when it oc-
cupies a large space in the  abdomen, compresses and dis-
places the surrounding organs, and crowds the intestines
into the lumbar and  iliac  regions, and its  fundus  reaches
the epigastric region.   After this period the fundus recedes
towards the umbilicus.
   The cervix uteri  becomes softer  and wider about the
fourth month, and afterwards diminishes in length,  and is
so expanded as to entirely disappear ;  at the seventh month
the uterus  has  an ovoid  form, and  its volume is  twelve
times larger than in its unimpregnated state.
   The appendages of the uterus are  also  considerably al-
tered in relation to the adjoining part;  the laminae  of the
peritonaeal folds, that form  the  broad ligaments, separate
and assist in forming a covering to the uterus.   The  vagina
is increased in length.   The ovaria, retained by their ves-
sels, do  not  ascend with  the fundus uteri; but, with the
Fallopian tubes,  are now  situated  on its  lateral  parts.
The round ligaments are  thicker,  more vascular, and yield
to its elevation.
   The abdominal parietes suffer very considerable  disten-
tion, so that the umbilical depression is entirely obliterated.
   As the magnitude of the  uterus increases, it assumes  a
cellular appearance of a deep red color, and  its fibres be-
come more evident.  On  the exterior, they take a direction
I have already described  ;  but  the  internal fibres  of the
uterine tissue have  some analogy with  those of the heart
and the tongue, in presenting an inextricable interlace-
ment, where no regular arrangement  can be distinguished.
Its interior  surface  contains, immediately after impregna-
   vol.  n.             36 
282         ORGANS OF GENERATION, &c.
tion, an albuminous layer, which increases with the organ
in the  earlier periods of pregnancy, and subsequently be-
comes a vascular membrane.  Dr. Hunter, who first care-
fully described it, called it the decidua, from its being ulti-
mately cast off from the uterus.   It is supposed to favor
the adherence of  the ovum to the internal surface  of the
uterus.
   The arteries  are now observed to  have  very  frequent
communications, and  in their course  are remarkably en-
larged  and convoluted.  But  the  veins are  much  larger
than the arteries,  their diameter, as we  have  stated, being
such as to distinguish them  as sinuses ; these materially
contribute to form the great bulk of  the uterine  parietes.
The lymphatic  vessels also become  very voluminous.  It
is evident  that the quantity of blood that traverses  the
uterus, is in relation to the changes it has undergone, and
the new functions it is required to fulfil.


     DEVELOPEMENT OF  THE  OVUM IN THE  UTERUS.

   The  ovum is  quite unattached during the first  period
of its  abode in  the  uterus ;  but in  the  course of the
second month its dimensions  have increased ; it  becomes
covered with  filaments  which ramify in the manner of
blood vessels, and are implanted into the decidua.   About
the third month they exist on  one side of the ovum only,
and are connected with that part of the deciduous mem-
brane, forming the placenta.  The ovum in the remainder
of its  surface,   presents  a  flocculent  layer,  sometimes
termed the decidua reflexa.
   The ovum, at  the  termination of  the second month, is
of the size of an  egg  ; and, when there has been an abor-
tion, we trace very distinctly the membranes which inclose
the embryo, viz. :— 
IN THE FEMALE.
283
        MEMBRANES WHICH  INCLOSE THE FffiTUS.

  1st.  The amnion, a  membrane placed  next to and di-
rectly enveloping the foetus; it is very thin  and pellucid,
but firm in texture, and not  easily torn ; it covers the pla-
centa, is reflected over the umbilical  cord, and terminates
at the umbilicus.   It is united  to the chorion  by  the inter-
vention of a gelatinous  substance.
  2d. The chorion, a  flocculent, spongy membrane, com-
pletely investing  the  ovum, and lining the uterus ; this
membrane is considerably thicker in the earlier than in the
more advanced stages of utero-gestation ;  it then becomes
transparent, and is united to  the amnion in the manner just
mentioned.
  3d. The decidua, which may be  properly considered as
the membrane lining the uterine cavity ; it is mueh thicker
than either of the  other membranes, but  its  texture is less
dense, and it is very easily torn.  It is placed between the
proper membranes of the impregnated ovum and the  ute-
rine surface.   The decidua  is  only formed  by the  uterus
during impregnation :  its formation commences  with con-
ception.   At first  it is a mere fluid  secretion, which after-
wards  assumes a  flocculent membranous appearance;  it
increases in extension and thickness  in  proportion to the
evolution  of the uterus.  It is adherent to the inner  sur-
face of that organ, and is extended over the chorion, to
which it is connected by a vascular attachment; it is always
thrown off after parturition.
  The decidua serves as a capillary  system, intended to be
the medium of communication  between the  blood vessels
of the mother and  the foetus.  The decidual vessels receive
the arterial blood of  the former, and these vessels are ex-
tended over a  very considerable surface of tubular struc-
ture, which, in its distribution, is in  apposition with the 
284         ORGANS OF GENERATION, &c.

infinite ramifications of the umbilico-placental vessels at
innumerable  points;  and  by these means  the required
changes in the blood of the foetus are as effectually pro-
duced, as the changes called for in the pulmonic blood are
produced by the  peculiar  arrangement of the  pulmonary
apparatus.  When  the  arterial blood of the  mother has
produced the desired effect on that of the foetus, it is re-
turned by the decidual veins to the surface  of the uterus,
where  it  enters into  the  general venous system of the
mother.
                    LIQUOR AMNII.

  The membranes contain a quantity of fluid termed liquor
amnii, which is  augmented in proportion to the advanced
state of gestation.  According to Professor Vauquelin, it
is formed of water, albumen, soda, muriate of soda, and
phosphate of lime.  The uses of this  fluid  are  to afford a
soft medium for  the  residence of the foetus, to which  it
allows a  free motion, and  protects its  delicate structure
from any external injury, to which, from the exertions of
the  mother,  it might occasionally be liable.   The waters of
the  amnios  are also useful in parturition, by dilating the
orifice of the uterus, and lubricating the external organs of
generation.


              THE  PLACENTA.   (Fig. 95.)

  The placenta  is  a  rounded, oblong and soft mass, by
means of which the ovum  is attached most intimately to
the  uterus.  This body is generally about eight inches in
its greatest  diameter,  six in the smallest, and one thick ;
but it gradually becomes  thinner  towards  the  circumfer- 
IN THE FEMALE.
285
ence.  Its thickest portion is where the  umbilical cord is
connected to it.
  This organ forms a most important  part of the uterine
contents :  its structure is entirely vascular, with the simple
interpositon of cellular membrane;  so  that  in  its general
substance, when excluded from the uterus, it is  found to
consist of the different branches  and  divarications of the
umbilical arteries and veins, united together by a fine cellu-
lar  tissue.  The  whole of this organ  is  strictly  foetal: it
contains within its structure cells or sinuses of  consider-
able extent, into which the  uterine  vessels at the point of
contact open, and over which their contents are circulated
and returned,  as  long as  the organ  is attached  to  the
uterine surface.   This cellular part of  the  placenta  has
acquired the name of the maternal portion.
  The placenta possesses within its structure the  means of
two distinct  circulations,  each  of which  is continued
through distinct channels: the one  passes the  blood from
the uterine  parietes into the placental  cells, and returns it
back to the  uterus : this is properly the maternal circula-
tion, and  continues as long as the  placenta  is attached to
the uterine  surface.  The other conveys the blood of the
child from its body, and back again through the numerous
ramifications of the umbilical vessels: this forms the foetal
circulation.   These two circulations  are  so  completely
separate and distinct, that they do not interfere with each
other: each is entirely unconnected with, and independent
of the other; as far as positive communications of vessels
are concerned, the foetal vessels do not pass their contents
into the placental  cells, neither do the uterine vessels, com-
municating  with  the placental cells, pass their  contents
into the foetal structure.   There is no mixture of foetal  and
maternal blood ; and no circulating communication, direct
or  indirect, exists  between  the  foetus, from  apposition at 
286         ORGANS OF GENERATION, &c.
the part to which the placenta is attached and  through its
medium.
  A satisfactory notion, therefore, of the mode in which
the principles of life are communicated  to  the  embryo, of
the materials from  which  it is  evolved, or the manner in
which the placenta  is appropriated to its service, has hither-
to never been obtained ;  yet there  are some points which
are obvious and  acknowledged.   The following are  facts
which almost admit of demonstration.
  1st.  When  conception  has taken  place, a principle of
internal action and  growth is established in the uterus, by
which its parietes are enlarged in  every direction, and its
cavity is increased in capacity.  2d. One of the immediate
effects of this primary change, is a  secretion furnished by
the vessels of its  internal  surface,  which  at  first becomes
the connecting medium between  the  mother and the em-
bryo, and afterwards the deciduous membrane.  3d. When
the ovum  is received into the uterine cavity, it  attaches
itself to a point  to which the uterine  vessels  are more par-
ticularly directed, and at which  also  certain vessels  from
itself are implanted.  4th.  These several parts increase in
size until the rudiments of the  placenta are formed, and
there is a regular increase  of its whole  substance, propor-
tionate to  the demand of the embryo  for nourishment, and
to the uterine growth.
  The placenta adheres  to the uterus by a simple apposi-
tion of parts, and by that peculiar  connection  of  vascular
circulation which subsists  between the  uterine vessels at
the point of contact, and the placental cells.  The blood
vessels of the gravid uterus run  through  its parietes in  a
serpentine  direction: and,  in the  distribution of blood, the
venous system possesses  a larger diameter than the  arte-
rial.  Though the placenta is in apposition in so simple  a
manner with the  uterine surface, it is  not in  immediate
contact with it, the deciduous membrane being interposed 
IN THE FEMALE.
287
becomes the bond of union  between  the two, except at
those points at which the uterine vessels pass  their blood
into the placental cells.
  The placenta is commonly attached to the fundus uteri,
but there is no part of its internal surface at which  this
organ may not occasionally be found.
              OFFICE OF THE PLACENTA.

  The office of the placenta is strictly foetal;  it is an organ
originally formed for and appropriated to the service of the
foetus, and is the only communication between the mother
and her infant: it is the  sole medium through which the
principles  of nourishment and growth  can be conveyed
from the one to the other.  The foetal blood distributed
by the branches of the umbilical arteries over the placental
mass, receives, as before stated, from the decidual appara-
tus, certain additions in that circulation necessary to foetal
life;  and is returned  to  the child by the  umbilical vein,
replete with that vitality which it has acquired in its passage
through the placenta.  The blood of the child  under this
state of improvement, if I may be allowed the expression,
may  be compared to that of the adult after its passage
through the lungs.   Thus if interruption to  the return of
the foetal blood, from the placental circulation, occurs from
any cause, the life of the foetus is as certainly destroyed, as
if the free passage of the air into  the lungs was prevented
during breathing life.


                   funis umbilicalis.

  The funis umbilicalis is that vascular cord which, passing
from the placenta to the  umbilicus of the  child, maintains 
288         ORGANS OF GENERATION, &c.
the communication between the foetus and  the  placenta.
Its length is almost two feet;  it is composed of two arteries
and one vein, the spaces between which are occupied by a
gelatinous  substance, contained in  cells, which  serves to
prevent any obstruction to the current of the blood from
accidental  compression.   The  funis  is covered  by the
amnion, or inner membrane of the ovum, and  the vein is
sufficiently large to reconduct to the foetus the whole or an
equal quantity of blood to that which is conveyed from the
two  arteries  from it to the placenta.   The  arteries  twist
round the vein in a beautiful spiral manner.
  The funis seems to  be the production of the placenta,
for, soon after the birth of the child, there is a spontaneous
separation of the funis at the umbilicus.


                  UMBILICAL VESICLE.

  In the first months of gestation, a vesicle is found in the
body  of the  umbilical  cord,  between the  chorion and
amnion, near the umbilicus :  it  receives small vessels from
a prolongation of the mesenteric artery and the meseraic
vein.   It contains a  yellowish fluid, the uses of which are
not known : after the fourth month it  becomes absorbed.
  Sometimes this vesicle has been observed, at the full
period of gestation, placed near the placenta ; it is connect-
ed, as before  stated, by vessels to the intestines, at the
termination of the ilium or coecum.  At the  lower end of
the anal  intestines  there projects another vesicle or sac to
which the name of allantoid  has been given ; it  exists in
all the mammalia, and in the human  embryo it appears
about the  fourth week, but  by the third month it disap-
pears : the use of this vesicle also is unknown. 
IN THE FEMALE.               289
                THE BREASTS (maMMJe).

  The breasts form part of the generative organs ; before
the age of puberty they are small and flat, but in the adult
and well formed female, they present two hemispheres, or
conical eminences, covered  by a smooth semitransparent
skin, softer and less colored than that of the other parts of
the body.
  Near the  centre of each  breast  the  color of the  skin
abruptly changes, and assumes a rosy tint in young females,
and a reddish brown one in women who are  pregnant or
have suckled several children.  This deep colored circle is
called the areola of the nipple.
  The nipple (papilla)  rises in the middle of the areola ;
and is always of the same color: it is susceptible of a kind
of erection.
  The skin of the areola and  nipple has a wrinkled  ap-
pearance, and  is remarkable for its  tenuity : it  presents a
number of sebaceous  glands,  which furnish  an  unctuous
fluid calculated to protect these parts against  the action of
the  saliva of the child.  We  observe upon the  surface of
the  nipple numerous  very fine papillae, in which are  the
orifices of the lactiferous ducts.
            ORGANIZATION OF  THE BREASTS.

  Beneath the skin there  is a  layer of adipose tissue, and
it is chiefly to this that the breast owes its size and form.
  The mammary gland is situated behind the adipose tissue,
and before the great pectoral muscle;  it has a convex and
uneven surface,  and  an  irregularly  circumscribed  base.
Adipose tissue is also found in the intervals which intersect
the lobules.
  vor.. n.              37 
290         ORGANS OF GENERATION, &c.

  The tissue of the mammary gland consists of an assem-
blage of lobes of  different  sizes, closely connected  with
each other by a dense cellular tissue.   Each of these lobes
is composed of several lobules,  which are obviously form-
ed of granulations of a pink color, and the size of a poppy
seed.  If we further examine these small granules, we find
that they consist of a number of minute  vesicles and an
organized tissue.

                         Fig. S2.
  Fig. 92, represents one of the mammae  dissected from
the pectoralis major muscle.
   a, the skin.
  b, the same dissected and reflected to show
  c, d, the mammary glands;
  e, the origins of the lactiferous ducts, and
  /, the nipple. 
IN THE FEMALE.
291
  The lactiferous ducts arise from the granulations of the
vesicles just mentioned ;  they commence in capillary tubes,
termed the  tubuli lactiferi, which uniting into branches,
collect into trunks, and proceed towards the centre of the
gland.  Those of the different  lobes do not communicate
with the others, so that there are as many series of vessels
as there are lobes in the gland; but  they all terminate in
fifteen or sixteen sinuses  in the centre of the nipple, and
open separately on its surface.
  When the nipple is contracted, the lactiferous canals
are compressed, and the milk usually ceases to flow ; but
by the sucking of the  child a  vacuum is produced, into
which  the milk  very readily escapes from the orifices  of
these canals.
                OFFICE OF  THE  MAMMJE.

  The child continues for some time after birth, depend-
ent upon the maternal system for its nourishment, and a
food is provided which alone is suitable to the  delicacy of
the infantine organs.  This food is the milk ; it is furnish-
ed by the mammae until the termination of nursing, or con-
tinues until the end of the second year.
  The color, odor,  and taste  of milk is known to  every
one ; it is one of the most azotised  glandular liquids :  but
there is no  fluid secretion  more readily modified  by the
diet, by the time  after delivery, by medicines, or by affec-
tions of the  mind.  On the average, the  milk of a healthy
person, according to BERZELius,is composed of milk, pro-
perly so called, and cream. 
        ORGANS OF GENERATION, &(..

 Milk contains :
   Water,.......928-75
   Cheese with a trace of sugar,    28-00
   Sugar of milk,.....    35-00
   Muriate of potass,  ....    1-70
   Phosphate of potass,  .   .   .     0-25
   Lactic acid, acetate of potass, and
     lactate of iron,   ....     6-00
   Phosphate of lime, ....    0-30

Cream contains :
   Butter,.......      4-5
   Cheese,.......     3-5
   Whey,.......     920
n this last 4-4 of sugar of milk, and salt is found. 
ART.   XV.
                      THE FCETUS.


             PECULIARITIES OF THE FCETUS.

  The osseous system of  the foetus is found in a very dif-
ferent state to that of the adult;  the foetal bones are soft
and yielding.  The situations of many of them are occu-
pied by  mere cartilage;  indeed,  all the bones, prior  to
their assuming a regular form, are of a cartilaginous con-
sistence,  and the  parts termed epiphyses, that is, the ex-
tremities of long  bones, up  to the  period  of  birth have
entirely this character.  Most of the cylindrical  and some
of the flat  and irregular bones, are formed of several dis-
tinct parts, each of which has its centre of ossification, and
these parts can be easily separated by boiling,  or by macer-
ation in water.
  In the chemical composition of the bones of the foetus,
there is  a  smaller proportion of  the  phosphate of lime,
than in the adult.   The foetal bones are also more uniform
on their surface, as they are  not  marked by the action  of
muscles ; their cavities are  filled with gelatin  instead  of
marrow.
  The head is large in proportion to the body, and in the
bones of the cranium  we may observe very distinctly their 
294                  THE FCETUS.

fibrous structure.  In  a foetus about three months after
conception, the  commencement  of ossification  in  each
bone  is  like a  fine  irregular net-work, in the centre of
which, the fibres are  more closely  connected than at its
circumference.   In viewing the flat  bones of the foetus, at
a more advanced period, the osseous particles are observed
to have  a radiated  appearance ;  as the foetus,  however,
attains a larger growth, the osseous fibres increase in num-
ber, until a lamina is produced ; and  in  the progress of
ossification, other laminae are added, and a succession of
these  laminae form the more solid fabric of the bone.


                         Fig. 93.
  a, the os frontis, which at early life consists of two pieces
divided by a vertical suture termed the frontal.
  b, the anterior fontanel.
  In the child the cranium bears a large proportion to the
face, owing  to the size of the  brain, the absence of the
sinuses  in the forehead,  and of the  teeth  in the gums ;
and  the younger the  embryo, the greater  is  the  dispro- 
THE FCETUS.
295
portion  between the head  and the rest of the body.  Be-
tween the frontal and parietal bones, is the space called
anterior bregma, or  fontanel, (Fig. 93, b,)  formed by an
irregular quadrangular membranous substance, which com-
monly disappears before the child attains the age of two
years, the margins of the bones  being then united.  Be-
tween the middle of the lambdoidal and posterior extreme
of the  sagittal  suture, a similar membrane of a triangular
form is  also frequently observed, termed  the posterior
bregma, or fontanel, (Fig. 94, c,)  but in a well formed head
it is scarcely to be traced.


                         Fig. 94.
  a, the frontal suture.
  b, the anterior fontanel.
  c, the posterior.
  The rudiments of the teeth are situated in canals in the
jaws, in sacs called  the capsules of the teeth ; these con-
sist of two membranes, containing  a pulpy matter.   The 
296
THE FCETUS.
 inner membrane, about  the sixth month,  forms a thin
 layer of enamel; and at the period of birth  the  shells of
 ten teeth are found in each jaw.
   The fluids  in  the foetus, are  proportionally large  in
 quantity, and the solids generally softer than in the adult.
   The skin is of a florid color, in consequence of a greater
 degree of vascularity, and is generally  covered with  an
 unctuous substance, supposed to be secreted  by the vessels
 of the rete mucosum.
   Adeps is chiefly found near the surface of the body ; very
 little is formed in the interior parts  until later in life, when,
 in healthy persons, it afterwards  gradually accumulates  as
 they advance to a certain age.
   The  brain,  spinal marrow, and nervous  system, are
 proportionally large, but soft in  their  texture.  The vas-
 cular system, and glandular organs  bear the same  pro-
 portion.
   The  cornea  of the foetal eye  is  thick and prominent.
 The pupil is  occupied by the membrana  pupillaris, which
 is attached to the circumference of the inner margin of the
 iris, and continues there until the seventh month, when  it
 gradually  disappears in consequence of  being absorbed.
 This membrane is  very vascular, and separates  the two
 chambers of  the eye  from each other.  The only use that
 can be assigned to it  is, that it  is  an  organ  of secretion,
 which is  requisite for  the production of  the  humours
 during the rapid increase of the globe of the eye.   The
 crystalline lens is  almost spherical, and  numerous vessels
 pass from the ciliary process to be dispersed upon its cap-
 sules.
  The  meatus auditorius  is wholly  cartilaginous,  and
adheres to a ring of bone in which the membrana tympani
is placed.   The meatus externus, and membrana tympani,
are lined  by a  mucous membrane  which separates after
birth. 
THE FCETUS.
297
   In this stage of existence certain  glandular  bodies  are
 developed, the uses of which are still unknown, but which
 continue large and vascular till towards puberty, and after-
 wards shrink  and waste.   The  thymus gland is  one of
 these: it is situated  in  the upper part of the thorax,  be-
 tween the  laminae of the anterior mediastinum, and over
 the pericardium ;  processes of this gland always ascend on
 each side, as  far  as  the  neck.  It  abounds with a milky
 fluid ; but it  has never yet been observed to have  any
 excretory duct; nor has  the use of the fluid  or of  the
 gland yet  been  ascertained.  Part  of the  thymus gland
 remains during youth, but it usually disappears  altogether
 in old age.   The supra-renal capsules of  the foetus  are
 large, when compared to their diminished capacity in after
 life.
   As  the lungs have not commenced their functions, their
 appearance is extremely different from  what  it is  after
 they have been inflated by the inspiration of air: they  are
 proportionally  much  smaller, their color is  darker, their
 substance denser, and their specific gravity is  so  much
 greater that they sink in  water.
   The heart, in the foetus, is proportionally larger than in
 the adult, and the Eustachian valve is more  distinct; it is
 supposed to direct the current of blood, coming from the
 abdomen, through the passage immediately to be mention-
 ed, existing in the septum of the auricles : —
   This opening is denominated the  foramen ovale  : it is
 situated obliquely in the partition which separates the right
 and left auricles;  it  is nearly  of the  dimensions of  the
 orifice of the cava, and it is bounded by a muscular mar-
gin, termed annulus foraminis.  The greatest part of the
blood which arrives from  the inferior cava, is poured into
the left  auricle, during the diastole of the ventricles.   A
falciform valve, placed over the foramen, prevents its re-
turn, and appears likewise to preclude its course into the
  vol. n.              38 
298
THE FCETUS
left auricle, during the systole of the auricles.   The blood
passing through the foramen ovale keeps up the balance of
the circulation between the sides of the heart, till the lungs
are ready to receive it.   The  foramen is  then generally
soon obliterated.
  The pulmonary artery divides into  three branches ;  the
right and the left of which proceed to the lungs, while  the
middle one, termed  ductus  arteriosus, (Fig. 95, m,) which
is larger than both the other branches, passes in an oblique
direction to the beginning of the descending aorta.  The
ductus  arteriosus is  therefore  another temporary passage
for carrying a part of the blood of the right ventricle into
the aorta, without passing the circuitous  route through
the lungs; it thereby assists the foramen ovale, in keeping
up the communication required  between each  side of  the
heart, till the child has breathed; and by these means also
the aorta receives the force of both ventricles, to move  the
blood  through the umbilical arteries; without  this joint
action  it is probable  the  blood  would  not  reach  the
placenta, and again return to the heart.
   According  to  this dispositon of the circulating appara-
tus of the  foetus, it  is evident that the motion of  the
blood  must be  different from that in the adult.  The
blood from the placenta passes through the umbilical vein
as far as the liver; then one part of the  blood proceeds
into the liver and the other into the vena cava; from these
two parts it arrives at the heart, and rushes into the right
auricle, by the inferior cava, and into the left  by the fora-
men ovale.   The contraction  of the  auricles  succeeds
their dilation, and the blood is compressed  into the ven-
tricles ; these in  their turn contract  and propel the blood
into the aorta, except a very small portion, which goes to
the lungs.   By the  united influence of the  two ventri-
cles, the stream of blood  is forced through all the divisions
of the  aorta, and  returns to the  heart  by the  ven^ 
THE FCETUS.
299
cavae.  Lastly, it is  transmitted  to the placenta by the
umbilical  arteries, and returns to the foetus by the vein of
the funis.
  The motions of the heart in the  foetus  are very rapid ;
they generally  exceed one  hundred  and  twenty  in a
minute : the circulation necessarily possesses a proportion-
ate rapidity.
  The abdomen is proportionally larger; and the stomach
is rounder  than in  the adult, and commonly  contains a
small quantity of gelatinous matter.  The  omentum has a
very small quantity of fat between  its laminae.    From the
remarkable mode of nutrition of the foetus, it is clear that
its alimentary canal  and  the  chylopoietic  system must be
very peculiar.  The valvulae conniventes of the small in-
testine are  scarcely perceptible.   The appendix vermi-
formis is very large,  and is  inserted into the extremity of
the colon, which at this  time does not project to form a
proper caecum.  The large  intestine very nearly resembles
the small, its longitudinal muscular  bands being very in-
distinct.   The colon contains a blackish green  feces, of a
viscid  consistence, termed  meconium, which appears to be
a mixture of bile with secretions from the  intestines.
   The liver is so large as to occupy both hypochondriac
regions, and to extend some distance below the margin of
the thorax.   The gall-bladder is filled with   bile  of an
extremely dark color.
   The umbilical vein passes from  the  umbilicus, in a
duplicature of the peritonaeum, behind the  recti muscles,
to the fossa umbilicalis of the  liver, and thence to the left
branch of the vena portae, and transmits the blood from the
placenta  to the liver.   From the  umbilical vein, where it
terminates in the liver, a branch, called ductus venosus, (Fig.
95, A,) proceeds in a somewhat waving direction, and joins
 the left vena hepatica, where that vein enters the  cava.
 The ductus venosus  transports  part of the blood of that 
300
THE FCETUS.
vein directly to the heart, without the intervention of the
hepatic circulation.  The reason for this distribution of the
umbilical vein is not understood.
  The pancreas and  other  glandular organs are large in
their  relative  dimensions.  The kidneys  are formed  of
lobes, in number nearly corresponding with the papillae.
  The pelvis of the foetus is commonly so small, that the
principal parts of the organs, afterwards  situated in it, are
at this time contained in  the cavity of the abdomen.   The
urinary bladder is of a long form, and  extends almost to
the umbilicus.
  The urachus is a solid  fibrous substance ;  it is attached
to  the  fundus  of the  bladder, between  the umbilical
arteries, and, passing behind the linea alba to the umbili-
cus, disappears by degrees in the umbilical cord.  In some
instances it is hollow in a part or through the whole of  its
extent.
  The common iliac arteries divide, on  each side, into a
small external, and a large internal branch :  the umbilical
arteries arise from  the internal iliacs, are  directed over the
sides of the bladder, attach themselves to the urachus, pass
out of the abdomen by the  umbilicus, and are distributed
to the placenta.
  Soon after  parturition the  foramen ovale, ductus arte-
riosus et venosus, with the umbilical vein and  arteries begin
to contract and are in  general  completely closed, the ves-
sels appearing like ligaments within a year after birth.
  In the very young male  foetus, the testes are  situated
in the cavity of the abdomen, over the psoae muscles, and
a little below the kidneys, so that they constitute a part of
the abdominal organs, and in a similar manner with them,
are connected to  the  body  by a process of peritonaeum,
which subsequently forms the tunica albuginea.  Between
the testis and scrotum a  fibrous and vascular substance is
extended, called by Hunter, gubernaculum,  which he con- 
THE FCETUS.
301
sidered as a principal agent in directing the course of the
testis  in its  descent.   This  remarkable passage of the
testis from the abdomen, through the ring into the scrotum,
is limited to no period, but it usually occurs about the last
month of gestation.   No  satisfactory explanation has ever
been offered as to  the cause of this singular transit of an
important organ to a distant situation.  It has been ad-
duced, by Blumenbach, as a striking illustration  of  a vita
propria, without the peculiar influence of  which, so re-
markable  and  unique a  movement,  similar to no  other
function in the system, cannot even be imagined. 
302
THE FCETUS.
Fig 95.
 
THE FQSTUS.
303
  Fig. 95, is a representation of the manner in which the
foetal circulation is carried on.
  a, the placenta.
  b, portion of the amnion which covers the placenta.
  c, the chorion.
  d, the umbilical vein.
  e, branches of the umbilical vein going to the liver.
  / the vena portae.
  g, hepatic branches of the preceding.
  h, the ductus venosus.
  i, the vena cava ascendens or inferior.
  k, the heart turned to the right.
  I, the vena cava superior or descendens.
  m, the ductus  arteriosus.
  n, the iliac arteries, the internal giving off
  o, o, the two umbilical arteries going to the placenta.
  p, the liver  turned to the right  side in order  to show
 the veins beneath it. 
ART.   XVI.
SEROUS SYSTEM, AND CELLULAR TISSUE.
          THE PLEURA AND  THE  PERITONEUM.


   Although, in the  description  of the contents of the
thorax and the abdomen, we  have  frequently had occasion
to advert to the serous membrane  covering the several or-
gans, still the serous membranes in general, and the pleura
and peritonaeum in  particular, claim a more extended no-
tice ;  indeed, the two  latter  can be  studied with greater
advantage, after an acquaintance with the anatomy of those
organs which they invest.
   The serous  system occupies the  exterior of the major
part of those organs, which are lined by the mucous mem-
branes : such as the stomach, the intestines, and the lungs.
It is found round all those parts which are essential to life,
as the brain, the heart,  and the abdominal viscera.  It also
lines the sides of  the cavities  of the chest and abdomen, so
that the organs are not in  contact with the sides, or with
the adjoining organs, except  by the  intermediation of the
peritonaeum.
   The serous membranes present  generally an envelope,
investing the organs so as not to be contained within, and
which, if it were possible to dissect these organs from their 
SEROUS SYSTEM, Ac.
305
spective  surfaces, would  be  removed  perfectly entire.
This envelope, in this respect, has been  compared to a
double night  cap placed on the head, a trifling simile, but
which  however, conveys a  correct idea of the manner in
which  these  membranes are situated.   From this disposi-
tion, it is easily conceived, that the serous membranes are
not perforated by the vessels and nerves of their respective
organs, but that  by  doubling  they provide  a  sheath for
those organs.
  The internal surface of this membrane, although in ap-
position  with, completely separates the adjoining organs
over which  these membranes are spread, forming, as it
were, an integument to the internal organs, which may  be
compared to  the skin investing the exterior of the body.
  The external surface of the  serous membranes adheres
to the adjacent organs : these membranes  are rarely  found
unconnected  on both  surfaces.  The  tunica arachnoides,
at the  base of the brain, and a few others are exceptions;
and where serous membrane is adherent it is perfectly dis-
tinct from the organ  it invests: there is no connection be-
tween  their reciprocal organizations; they are merely united
by  a loose cellular tissue.
   All  the  serous membranes are  composed of  a  single
sheet,  which, where it  is  thick,  may be separated into
cellular laminae ;  it only differs from the cellular  tissue  in
being more condensed.  By inflating  the  tissue  beneath,
the cellular  structure is rendered very apparent.   No
fibres are met with in its structure (a distinctive  character
of  other organs), it is therefore  similar to the cellular
tissue.
  The pleura is one  of the class of serous membranes, one
portion of which forms  the investing  tunic of the  lungs,
while the other is attached  to the inner surface  of the ribs,
the upper surface of the  diaphragm, the mediastinum and
the intercostal muscles.  The  pleura, covering the lungs, is 
306
SEROUS SYSTEM, &c
termed pleura pulmonalis, the reflected portion, pleura cos-
talis,  pleura diaphragmatica, or pleura pericardiaca, in re-
ference  to the surface to  which it adheres.
  The surface of the heart is invested  by a similar serous-
membrane, and  it is reflected so as to form a sac, termed
pericardium, which contains the heart.
  The peritonaum is  the most  extensive of  the  serous
membranes:  it  is thin  and  transparent;  it  has  a very
complicated  course; not  only  does it  invest the inner
surface  of the  parietes of the  abdomen, but  it  forms
several  remarkable folds in that cavity, and is prolonged
under the form of an envelope over most of the abdominal
organs.
  It is usual to describe  the peritonaeum as presenting a
sac without aperture, enveloping those organs whose exter-
nal appearance is smooth and  glossy, but, in reality, it is
covered by fine villosities.  It  is everywhere  in contact
with itself.  I have stated that it is an  imperforated sac,
but, in the female, there is a slight exception, for it is found
to be perforated  by the  fimbriated extremity of the Fallo-
pian  tube, the mucous membrane of which  seems  to be
continuous with  the  peritonaeum.
  In  the umbilical region, the peritonaeum  lines  the pos-
terior part of the linea alba, closes the posterior  orifice of
the umbilicus, and is extended behind the wide muscles
of the abdomen.  On the right, it  meets the ascending
colon;  on  the  left, the descending  colon ;  and  forms
around  this  intestine two  folds, which  are  named  the
lumbar mesocolon, and which serves to  attach the intestine
to the posterior  part of  the abdomen.  The peritonaeum
passes before the kidneys, being separated from them by a
greater  or less  quantity of fat and cellular tissue; then
covering the uterus,  the  spermatic  and renal vessels,  the
vena cava and the aorta,  it advances on each side towards
the vertebral column, before which  it is  reflected to form 
SEROUS SYSTEM, &c
307
 the mesentery, or that immense fold  which  supports and
 envelopes the small intestine.
   In  the hypogastric region, the peritonaeum descends
 from the umbilicus to the pubes, and, covering the urachus
 and the umbilical  arteries, it is  directed  over the summit
 and the posterior  part of the bladder.   It presents, how-
 ever, differences according to the sex :  in the male, it in-
 vests  the  base of the vesiculae seminales, and is reflected
 over the  rectum,  constituting the mesorectum.   In  the
 female, the peritonaeum  is extended  from the bladder in
 front of the vagina;  it then invests the anterior and poste-
 rior surface of the uterus, and is prolonged, laterally, so as
 to form the broad  ligaments.
   In the lateral parts of the hypogastric region, it is first
 reflected upon the parietes of the  abdomen, over the iliac
 fossa, covering part of the  iliac and psoae muscles, embra-
 cing, to the left, the sigmoid flexure of the colon, by means
 of the iliac mesocolon, and, to the right, the coecum and its
 appendix, by means  of the mesoccecum.   From  thence it
 ascends forwards  behind Poupart's ligament, and forms
 two depressions on  each side, termed the inguinal fossae.
 which are separated from  each other by the fold of mem-
 brane which supports the  remains of the umbilical artery.
 The external fossa is generally widest, and its peritonaeum
 dips a little into the orifice of the inguinal canal:  posteri-
 orly, the peritonaeum is continued from the iliac fossa to the
 lumbar mesocolon.
  The epigastric  portion of  the  peritonaeum, to the  left,
 invests a  considerable part of the inferior surface of the
 diaphragm, and sinks into the  most retired parts of the
 region of the hypochondrium, as far as the vertebral column,
 whence it is reflected over the  surface of the spleen, and
the posterior surface of  its vessels.  At  the  cardiac ex-
 tremity of the stomach, it  is continued  into the anterior
lamina of the great omentum.   The laminae of peritonaeum, 
308
SEROUS SYSTEM, &c.
which are comprised between the spleen and  the stomach,
are called the gastro-splenic omenta.  In  the centre, the
peritonaeum passes  from the diaphragm, upon the anterior
surface of the stomach, descends over the intestines to the
most dependent part of the abdomen, and is reflected from
below upwards, as  far as the convex  edge of the  colon,
thus contributing to form the great omentum.  It then in-
vests the inferior arch of the colon, forms the inferior lamina
of the transverse mesocolon, and is  continuous with the
lamina of the mesentery.
  On the right,  the peritonaeum is reflected over the liver,
and forms foldings which constitute its ligaments.
  Under the neck of the gall bladder we find a triangular
aperture, the foramen of Winslow, through which is seen
the laminae of the peritonaeum,  constituting the  hypogas-
tric omentum, or the capsule of Glisson; which contains
in its  duplicature the hepatic and pyloric vessels, the coro-
nary vessels of the  stomach, and  the  cystic  and hepatic
ducts, together with the ductus  communis choledochus.
This lamina is then  directed over the posterior surface of
the stomach, covers the upper  surface of the mesocolon,
and the concave surface of the right lobe  of the liver.


                 OMENTA, OR EPIPLOA.

  The omenta are  composed of folds of the peritonaeum
connected together  by  cellular tissue, containing fat.  Al-
though I have referred to them in the preceding description
of the peritonaeum,  still it is an  advantage to the student
to have  before him a succinct and methodical  arrangement
of them.
  The hepato-gastric  omentum,  or the smaller  omentum.
The peritonaeum passes off double from  the liver  to the
lesser curvature of the stomach.   It is limited, on  the right, 
SEROUS SYSTEM, &c
309
by the large hepatic vessels and  biliary ducts, which  are
inclosed in the capsule of Glisson ;  and, on the left, by
the oesophagus and the cardiac orifice of the stomach.  Be-
hind the capsule,  just named,  we find an aperture large
enough  to  admit  a finger, which was first  described by
Winslow, and  has been called the foramen of Winslow :
this foramen maintains a communication between  the large
sac of the omentum, and the common cavity of the abdo-
men.   The two peritonaeal laminae of the smaller omentum
separate from each other and invest the stomach, and, by
their continuation, form the anterior lamina of—
  The great omentum, a large  fold of peritonaeum : it is
free and floating upon the front of the convolutions of  the
small  intestine.*   It is irregularly quadrilateral : it is at-
tached, anteriorly, to the great curvature of  the stomach ;
and, posteriorly, to the arch of the colon.  It is formed of
two laminae, each composed of two lamellae of peritonaeum.
The anterior lamina is a continuation  of the serous  cover-
ing, from the superior and inferior surfaces of the stomach;
it  extends, laterally, as  far as  the commencement of  the
duodenum and  the  inner surface of the spleen, to both of
which it is connected.   The  posterior lamina has  its origin
in  a similar manner from the serous membrane of the sur-
faces of the colon.  At the opposite side of the colon,  the
laminae unite to form  the  mesocolon.  By the membrane
thus continued, a  large irregular sac  is  formed,  of which
the smaller omentum, stomach, and anterior portion of  the
great omentum, constitute  the  anterior, and  the  posterior
portion of the great omentum,  the colon, and mesocolon,
the posterior part of the sac.  In young subjects, the
parietes of the sac is so complete, that it  may be inflated
from the foramen  of Winslow  ; but in old and emaciated
persons, the laminae of which it is composed  become reti-
cular in consequence of absorption.
•See Vol. I. Fi-. 197, r, i, i. 
310
SEROUS SYSTEM, &t.
   We find, between the laminae of the great omentum, a
 considerable quantity of fat and blood vessels.
   The colic omentum is situated behind the great omentum;
 it consists of a fold of the  peritonaeum which exists on the
 right side only, nearly filling the angle formed by the union
 of the right and  transverse portions of the colon.   Fre-
 quently  it extends as far as the coecum or to  the spleen.
 Its two laminae are separated by arteries and veins belong-
 ing to the colon.
   The gastro-splenic  omentum  is formed in a similar man-
 ner  by the peritonaeum, which, from  the  fissure  of the
 spleen, proceeds over the cardiac extremity of the stomach.
 It contains in its  substance  the splenic vessels and vasa
 breviora.
   The omenta, as well as the internal surface of  other
 serous membranes, are constantly moistened with a fluid
 nearly resembling  the serum of the  blood.  This fluid is
 incessantly poured out by the exhalents, and constantly
 taken  up by the  absorbents.  Its  quantity varies; in the
 natural state it is merely  a dew, but in dropsies of the
 abdomen it amounts to several  gallons.   Indeed the  quan-
 tity of serous fluid  varies astonishingly in the different acute
 and chronic diseases ; and  the  exhalent surfaces pour out
 more or less of this fluid, according as they may be prima-
 rily or sympathetically affected.
   The serous exhalations give a facility to the due actions
 of the respective  organs,  by  permitting them  to  move
 on each  other without injury.  The great omentum  is
 supposed  to  preserve  the  intestines  from the  ill effects
 which might result  from violent  exertions; it serves to
 retain  their temperature, and  to receive the superfluous
depositions of fat. 
SEROUS SYSTEM, &r
311
                 CELLULAR TISSUE, ETC.

  The cellular tissue is distributed  throughout the animal
system; it is  composed of a very  fine  web, formed of a
great number of thin plates,  which  crossing  in  an endless
variety of directions,  have  between  them  interstices or
cells, which communicate together and serve for the recep-
tion of fat or  serum.   The  cellular system, examined in
respect to the organs, presents, 1st, an envelope or outward
limit to the organs :  2d; it  enters freely into the texture of
each organ, and constitutes a part of its  structure.
  In many parts the  cellular tissue  is  very elastic, and
capable of extension, but  in other  parts it is more dense
and resistant.  In some instances the cellular tissue adheres
to one of the surfaces of an organ, as, for instance, the
skin ; in others it entirely envelopes it, as  in parts where
it is universally connected  with  the adjacent parts.  The
skin universally exhibits, wherever  you examine it, a sub-
jacent cellular stratum.   This subcutaneous cellular tissue
varies considerably in its texture ; its density in  the scalp
is remarkable, which on this  account is not  easily separa-
ted from  its  aponeurotic  and muscular connection.   In
the face, it is very loose,  and  extremely abundant:  it is
equally lax in almost  all  parts of  the thorax, and in the
extremities ; and  therefore, accomodates  itself easily to the
motions of the  muscles.  It  is only  in  the palm of  the
hand and the sole of the foot, that its texture, increasing
in density, forms a stronger adhesion to the fascia and the
skin.   This arrangement is highly  favorable to the uses of
these two parts, which  must  accommodate themselves to
bodies, particularly enabling  the  hand  to seize,  grasp  and
hold them.
  The texture of the subcutaneous cellular tissue is dense
about the  capsular ligaments, for which reason the adhe- 
312
SEROUS SYSTEM. &c.
sion of the skin is  stronger; hence, the contractions  we
observe at  those  parts in the extremities of infants, very
little fat being admitted into the condensed tissue.
  There is a submucous  cellular tissue, but its texture is
more  compressed than  that of the tissue  we  have been
considering above.   Consequently there is  a  difficulty in
dissecting, and separating it distinctly from its connections.
  Under almost every part of the serous system, and like-
wise in the two  preceding situations, we find a  cellular
layer generally very abundant and very loose.
  Around each of the arteries there is  a strong, dense and
elastic layer, which  is sometimes  considered as one of its
proper membranes :  it arises almost imperceptibly from the
adjacent cellular tissue, which  becomes condensed, and is
so intimately  united to the vessel, that it  may be  wholly
detached, and forms a sheath or  canal corresponding to
that of the artery it  surrounds and  supports.  Veins  are
provided with an  external covering of cellular tissue analo-
gous to that of the  arteries.
   With the exception we have named, all  the  organs  are
completely surrounded by  a  covering of  cellular tissue,
more or  less extensive, forming  a peculiar  medium  for
each ; a medium  in which they arc entirely immerged, that
insulates them from  each other.   After investing the sev-
eral organs, the cellular tissue enters into their intimate
structure, and forms one of their elements.  In those organs
which are composed of several parts, these parts are united
together  by it:  thus in  the stomach,  intestines, etc.  the
different membranes of which they are composed are con-
nected together by this web.  It sends a multitude  of pro-
cesses into the structure of  the lungs,  between the serous
membrane and  their parenchyma, between this and   the
bronchi, and between the bronchi and the mucous surface.
   In the  muscles and other organs the cellular tissue  first
attends and  surrounds,  through their whole course,  the 
                  SEROUS SYSTEM, &.c.              313

vascular and nervous ramifications which are found in their
composition;  and afterwards  unites  the  different  parts
which compose each organ.   " Every muscular fasciculus
or fibre, or vessel, or  nervous  filament; every portion of
fascia or ligament; every glandular particle, is inclosed in
a sheath  of peculiar cellular tissue, which, in  respect  to
those parts, fulfils the same purpose as the larger envelope
does in respect to the whole  organ."*
  Many fruitless  researches  have been made to determine
the peculiar  organization of the cellular tissue, yet but
little is known, except  that on a minute inspection we find
an assemblage of innumerable whitish filaments of extreme
tenuity, that are spread  over the thin transparent plates
that form  the cellulae.  Examined in a  favorable light, we
may distinguish its  exquisite  delicacy, and when  inflated,
it may be compared to the air bubbles in a  solution of
soap.f  There is no doubt, however, but some of the fila-
ments which compose  this tissue are exhalent and absorb-
ent vessels ; and  this  opinion is confirmed when we suc-
ceed  in making a very fine  injection ; we then observe a
multitude of vessels woven  in  every direction  with each
other, changing its white and transparent  hue, and  con-
verting it into a vascular net-work.
   Nerves are  plentifully distributed in the  cellular  tissue,
but  their ramifications are as white as the tissue  in which
they abound,  so  that  they cannot  be satisfactorily distin-
guished from  it.
   The plates of the  cellular tissue exhale a fluid which has
the greatest  analogy with that of  the serous membranes,
and which appears to have the same uses ;  namely, to
render the friction of the plates easy on each other, and
therefore  to favor the reciprocal motions of the organs, and

  * BlCHAT.
  t A beautiful preparation  may be made of cellular tissue, by inflating,
drying, and suspending^ in rectified oil of turpentine.
   VOL. II.             40 
314             SEROUS SYSTEM, &c.

even  the  relative change of the  different parts of which
they are composed.


                         FAT.

  Besides the serum, a fluid is found in many parts of the
cellular tissue of a very different  nature, which is  the fat.
This substance is contained  in distinct  cells that do  not
appear to communicate with the adjoining ones.  The size
and form of these cells are not less variable than the quan-
tity which  they contain.  In some individuals scarcely a
few ounces exist, while in others there is one or two hun-
dred pounds.
  Human fat is of a yellow color ; inodorous,—becoming
solid at 89° F.  It is composed of two  proximate princi-
ples, recently discovered by Chevreul, elaine and stearine.
  Some of the offices of the cellular tissue maybe collect-
ed from the preceding  observations:  a description of this
part of the  animal  fabric may very properly conclude  a
work on  descriptive anatomy, since the cellular tissue con-
stitutes a bond of union, which, diffusing itself everywhere,
connects and preserves the  whole natural  connection of
each part of the organized structure.  The  subcutaneous
cellular  tissue has  many  other  uses  ;  from it the   skin
acquires  a freedom of motion over the organ it covers, and
which is  particularly observable in muscular actions.   It is
also to this  tissue, that organs subjacent to the skin partly
owe the  facility with which  they move,  in those  rapid or
powerful contractions of which they are capable.
  As fat is a very slow conductor of caloric, it retains ani-
mal heat, and consequently is useful in  the animal economy
by contributing to secure  the  subjacent parts against the
vicissitudes of the atmosphere.   In the orbit  it forms a sort
of elastic cushion upon which the eye moves with facility. 
SEROUS  SYSTEM, &c.
315
In the palms of the hands and the soles of the feet, and
about the hips, it forms a layer, which  renders pressure
upon the skin and other soft parts less severe.  But prin-
cipally this  substance is deposited in cellular tissue, as a
store of  nourishment intended to supply the  exigencies of
the animal system;  as in  instances where food cannot be
obtained, and  in often  supporting the body under wasting
disease,  by being absorbed and carried again into the circu-
lation.
   Together, the cellular  tissue  and fat, are  useful as an
elastic vest, which guards the more sensitive parts  of the
interior  mechanism.  But in contemplating this as  well as
every other part of our organization, we cannot but admit
the admirable  mechanism exhibited in the human structure
and economy, and the infinite resources displayed by that
wise and benevolent being, who planned  the constitu-
tion and preservation of our bodies.
                          ERRATA.
 Page  4, line 6 from top, omit external.
  "   21,  "  2 from bottom, rearl does for do.
  "   29,  "  6 from bottom, read Acliillis for Achilles.
  "   31,  "  10 from top, read parietes for parie ties.
  "  264,  "  4 from bottom, read odoriferw for odorifirce.
  "  303,  "  6 from bottom, read pulmonary artery, for the vena cava superior or de-
scendens. 
 
GLOSSARY.
Abdomen, (abdere, to hide), the lower venter or belly, containing or
      hiding the  intestines, etc.
Acantha, (axavda, a spine or thorn), sometimes used for the spine.
Acetabulum, (acetum, vinegar), the socket for the head of the thigh-
      bone, resembling an ancient vessel for holding vinegar.
Acini, (acinus, a grape seed), the internal structure of several glands.
Acoustic, (ocxovoj, to hear), a term applied  to parts belonging to the
      ear, or to sound.
Acromion, [axgog, the extremity, and fo/no;, the shoulder), a process
      of the scapula.
Adenology, [adrjv, a gland, and lo-t'og, a discourse), the doctrine of
      the glands.
Adeps, fat, an oily matter contained in the  cellular tissue.
Adnata, (adnascor, to grow to), the external coat of the eye.
Albuginea Tunica.  The inner  proper coat of the  testicle is thus
      named from its whiteness.
Albumen, an animal substance of the  same  nature as  the  white of
      an egg.
Alveoli, (alveus, a cavity), the sockets for the teeth.
Amnion, (uufo;, a lamb), the soft  membrane immediately surround-
      ing the foetus.
Amphiarthrosis, (atufw, both, and agdnov,  articulation), an articu-
       lation admitting of on obscure motion. 
318
GLOSSARY
Anastomosis, [ava, through, and awfia, a  mouth), the communica-
      tion of vessels with one another.
Anatomy, (ava, through, and xefivw, to cut), dissection, or that know-
      ledge of animal bodies acquired by dissection.
Ancon, the  elbow, (from  d.yxwv),  because the bones,  being there
      united, are folded one into another.  Hence also,
Anconeus, a muscle situated there, and,
Anconoid, a process of the cubit, from ayxotv, the elbow, and eidog,
      shape.
Angeiology, [ayyeiov, a vessel, and i-oyog, a discourse), a description
      of the vessels.
Antagonist, [avn, against, and aycov, a struggle), an  epithet of a
      muscle acting contrary to another.
Antihelix, [uvti, against, and eilco, to turn about), the external part
      of the ear opposite  to the helix.
Antithenar, (avn, against, and devag, the palm of the hand), one of
      the muscles extending the thumb.
Antitragus, (avn, against, and  rgayog, a part of the ear), a promi-
      nence of  the ear opposite to the tragus.
Aorta, (aogxrj;  from arjg, air, and rrjgew, to keep), the great artery of
      the heart.
Aponeurosis, [onto, from, and vevgov, a nerve), a tendinous expan-
      sion, supposed by the ancients to be that of a nerve.
Apophysis, (anocpvco, to spring from), the process of a  bone, and a
      part of the same bone.  Epiphysis, a process attached to a
      bone, and not a part of the same bone.
Arachnoides, (aga/vj], a spider's web, and Eidog, likeness), a cobweb-
      like membrane, the second covering of the brain.
Arteria, (ar]g, air, and Tygeco, to keep), because the ancients thought
      that air was contained in the arteries.
Arthrodia, (agdgov, a joint), that kind of articulation which is shallow.
Arytenoides, (agvtaiva, an ewer, and eidog, shape), two cartilages of
       the larynx.
Aspera Arteria,  (asper, rough,  and  arteria, an  air-vessel), the
       trachea or windpipe. 
GLOSSARY.
319
Astragalus, (aaxguyalog, a die), a bone of the  tarsus: the  corres-
      ponding bones of some animal were used by the ancients as dice.
Atlas, the first  of the cervical vertebrae, so named from supporting
      the head, as Atlas was supposed to support the world.
Axilla, the  arm-pit.
Azygos, (a, without and t,vyog, a yoke), a term applied to any part,
      not having a corresponding part.


                              B.

Basilica, (fiaoilevg, a king), an  epithet, by way of eminence, given
      to one of the veins of the arm, to an  artery of the brain, and
      to a process of the occipital bone.
Biceps, (bis, twice, and caput, a head), composed of two heads.
Brachium (Pga%vg, short), because, in general, from the shoulder to
      the hand is shorter than from the hip to the foot.
Bregma, (figexa, to moisten), the space between the bones of the in-
      fant head through which the superfluous humours of the brain
      were supposed to pass.
Bronchi, (@goy%og, the windpipe), the ramifications of the trachea.
Buccinator, (buccina, a trumpet), a muscle of the cheek, much used
       by trumpeters.
Bursalogy, (fivgoa, a purse, and loyog,  a discourse), a description of
       the bursae mucosa?.

                               C.

Cecum, blind:  a term applied in anatomy to an impervious canal, or
       to a part which terminates abruptly in a pouch.
Calcaneum, (calx, the heel), the name of the os  calcis.
 Calvaria, or Calva, (calvus, bald), the upper  part of the cranium,
       which turns first bald.
Cancelli, (lattice-work), the  spongy substance in bones.
 Capillary Vessels, (capillus, a hair), the small ramifications of the
       arteries  and veins. 
.V20
GLOSSARY.
Capsule, a membranous production inclosing a part like a bag.
Caput Gallinagims, (a wood-cock's head), a little eminence in the
      urethra at the termination of the ductus ejaculatorius.
Cardia, (xagdta, the heart), the superior opening of the stomach, so
      called from being situated near the heart.
Ca tinivora, (caro, flesh, and voro, to devour), animals that  live on
      flesh.
Carotid, (xagoco, to induce  sleep), arteries  of the head and neck,
      which  if tied, the animal becomes  comatose, or has  the  ap-
      pearance of being asleep.
Carpus, (xagxog), the wrist.
Cartilage, gristle, a matter softer than bone, but harder  than liga-
      ment.
Caruncula.  This word is a dimunitive from  caro, flesh.
Cellula, (dimunitive  of cellai a cell), a little cavity or cell.
Cephalic Vein, (xecpalrj, the head), the ancients being accustomed to
      open this vein in disorders of the head.
Ceratoglossus, xegag, a horn, and ylwaaa, a tongue), a muscle run-
      ning from one of the cornua of the os hyoides to the tongue.
Cerebellum, dim. of Cerebrum, the brain, (xagrj, the head).
Cervix, the hinder part of the neck, the fore part being called Col-
      lum.
Choledochus Ductus (%oItj, bile, and de/o/uai, to receive), the com-
      mon bile-duct.
Chorda, (xogdrj, a cord or assemblage of fibres), a term applied  to a
      nerve of the tympanum, to the spermatic vessels, etc.
Chorion, (%a>giov, domicilium), the  outer membrane  involving  the
      foetus;  or %ogog, a chorus, this membrane being supplied with
      many blood vessels in  the quadruped.
Choroides, so called on account of its many blood vessels, resemb-
      ling the chorion.
Chyle, (/vhog, the juice), the milk-like fluid in the lacteal vessels.
Crystalline, (xgvcnallog), a term applied to the lens, from its re-
      semblance to ice.
Clavicula, (dim. of clavis,  a key),  the clavicle or collar-bone ; so
      called from its resemblance to an ancient key. 
GLOSSARY.
321
Clinoid, (xhvrj, a bed, and eidog, shape), processes of the sella turci-
      ca of the sphenoid bone, so called from their resemblance to a
      couch.
Clitoris, (xleico, to conceal), a part of the  female  pudendum con-
      cealed by the labia majora.
Coccyx, (xoxxv£, a cuckoo), the lower end of the spine, so called from
      its resemblance to the  beak  of that bird.
Cochlea, (xo/Xog, a conch), a cavity of the ear resembling the shell
      of a snail.
Ccecum, the blind intestine.
Cceliaca, (xoiha, the belly), the name of an artery in the abdomen.
Colon, (xwlov), the first portion of the large intestine.
Commissura, (committo, to join together), applied to parts which unite
      the hemispheres of the brain.
Concha, (xoyxq, a shell) applied to the hollow of the ear from its re-
      semblance to a shell.
Condyle,  (xovdvlog, a joint, a knuckle, a knot), an eminence in
      several of the joints.
Conglobate, (conglobatus, gathered together in a circle), a gland sub-
      sisting by itself, like those of the absorbent system.
Conglomerate, (conglomeratus, heaped together), a  gland composed
      of various glands.
Coraco ;  names compounded with this word belong to muscles
      which are attached to the coracoid process of the scapula.
Coracoid, (xogal;, a crow, and eidog, resemblance), like the beak of a
       crow.
Cornu, (a horn), applied to a process resembling a horn.
Coronary, (corona, a crown), vessels so called from surrounding the
      parts like a crown.
Coronoid, (xoqwvt], a crown, and eidog, shape), a process shaped like
       a crown.
Corpus Callosum, (corpus, a body, and  callus, hard), part of the
      medullary substance of the brain, supposed to be firmer  than
      the rest.
   vol. n.               41 
322
GLOSSARY
Corticalis Substantia, (cortex, bark), the exterior or cortical sub-
      stance of the brain.
CosTiE, (custodio, to guard), the ribs, because they guard the heart, etc.
Cotyledons, (xoxvlv, a  cavity), glands, in some animals, dispersed
      over the chorion.
Cotyloid, (xotvln, an old  measure, and eidog, shape), the cavity for
      receiving the head of the thigh-bone, resembling the rotuli.
Cox.e, the haunches.
Cranium, (xgaviov, the skull, quasi, xagaviov, from xaga), the head.
Cremaster, (xgefiaco, to suspend), a muscle so called, because it sus-
      pends the testicle.
Cribriform, (cribrum, a sieve), perforated like a sieve.
Cricoid, (xgixog, a  ring, and  eidog, shape), the  annular  cartilage of
       the larynx.
Crista Galli, a portion of the ethmoid bone, so called  from its re-
       semblance to a cock's comb.  Crista, a term applied to other
       parts which resemble a crest.
Crura, (crus, a leg), applied to some parts, from their resemblance or
       analogy to a leg.
Crypts, (xgvTtrco, to hide), mucous follicles which are concealed.
Cubitus, (a cubando), that part of the  arm from the elbow to the
       wrist; because the ancients, during  meals,  used to recline
       upon it,
Cuboides, (xvfiog, a cube, and eidog, shape), a bone of the foot, re-
       sembling a cube.
Cucullaris, (cucullus, a cowl or  hood), a broad muscle  of the scap-
       ula, so called from its shape.
Cuneiform, (cuneus, a wedge), wedge-shaped.
Cuticula, (the dim. of cutis, the skin), the scarf-skin.
Cutis, the skin.
Ctsticus Ductus (xvaxig, a bladder, ductus, a duct), the  duct leading
       from the  gall-bladder. 
                          GLOSSARY.                     323

                               D.

Dartos (dega, to excoriate), muscular fibres which contract the scro-
      tum.
Decidua, (decido, to fall off), a membrane thrown off" from the uterus
      after parturition.
Deltoid, (Aelxa, the fourth letter of the Greek alphabet, and eidog,
      shape), resembling the Greek letter J.
Dermis, (degpa), the more solid skin.
Detrusor Urin.e, (detrudere), to thrust or squeeze out of.
Diaphragm, (diacpgaaao}, a partition), the transverse muscle which
      separates the thorax from the abdomen.
Diastole, (diaaxelXco, to  relax), the dilatation of the heart, auricles,
      and  arteries, opposed to systole, the contraction of the same
      parts.
Diarthrosis, (diagdgoa,  to  articulate), a movable  connection of
      bones.
Digastric, (dig, twice, and yaaxrjg, a belly), having two bellies.
Diploe, (dinloog,  double), the  spongy substance between  the  two
      tables of the skull.
Duodenum, (duodenus, consisting of twelve, viz. fingers' breadth), the
      first portion of the small intestine, so called from its general
      length.
Dura Mater, (durus, hard, and mater, a mother),  the outermost
      membrane of the brain ; the  ancients finding it harder than,
      and supposing it to give origin to, the other membranes of the
      body.

                               E.

Elaine, (elaiov, oil), the more fluid part of one of  the proximate
      principles of fat.
Embryo, (ev, in, and (igvw, to germinate), the  ovum  in utero before
      the fourth month, after which it is called foetus. 
324
GLOSSARY.
Emulgents, (emulgeo,  to milk  out), the arteries,  and veins  of the
      kidneys, so  called because,  according to the ancients, they
      strained, and, as it were, milked the  serum  through the  kid-
      neys.
Emunctores, (emungo, to wipe away), glands  which, according  to
      the ancients, received the  excrementitious matter from the
      noble parts ; as the parotids from the brain, the axillary glands
      from the heart, and inguinal glands from the liver.
Enarthrosis, (ev, in, and agdgov, a joint), an  articulation of bones,
      the same as arthrosis.
Encephalon, (ev, in, and xecpalrj, the head), the brain.
Enteric, (evxegov,  an intestine), belonging to the intestines.
Epicranium, (em,  and xgaviov), the integuments and aponeurotic
      expansion which are extended over the cranium.
Epidermis, (em, upon, and degua, the skin), the cuticle.
Epididymis, (em, upon, and  didvfiog, twins, the testicles), the small
      oblong body which lies above the testicle.
Epigastric, (em, upon, and yaatvg, the stomach), the  superior part
      of the abdomen.
Epiglottis, (em, upon, and yhaxxig, lingula), one of the five cartila-
      ges of the larynx, situated above the glottis.
Ephippium, (em, upon, and imtog, a horse), part of the os sphenoides,
      so called from its resemblance to a saddle.
Epiphysis, (em, upon, and cpvco, to grow), see Apophysis.
Epiploon, (em, upon, and nlew, to sail), the omentum, or that  serous
      membrane of the abdomen which covers  the intestines, and
      hangs from the bottom of the stomach.
Ethmoid, (rjdfiog, a sieve), so called because it is perforated like a sieve.


                              F.

Falciform, (falx, a scythe), shaped like a scythe.
Fascia, (fascia, a band), a membranous expansion of certain muscles
      like a sheath.
Fasciculus, a little bundle, diminutive of fascis, a bundle. 
GLOSSARY.
325
Fauces, (the plural of faux), the top of the throat.
Fibrin, a peculiar organic compound, which is the most  abundant
      constituent of the soft solids of animals.
Fibula, (a clasp), the lesser  bone of the leg, which is thus named
      from being placed opposite to the part where the knee-buckle
      or clasp was formerly used.
Fimbria, a fringe, a term applied to parts of a fringe-like appearance.
Fcetus, the child in the womb past the fourth month, and fully formed.
Follicle, (follis, a bag), very minute secreting cavities.
Franum, (a bridle), the  membranous ligament under the tongue, and
       the one tying the prepuce to the glans.


                              G.

 Galactophorous, (yala,  milk, and cpegco, to carry),  conveying the
       milk.
 Ganglion, (yayyliov), an enlargement in the course of a nerve.
 Gastric, (yaanjg, the stomach), appertaining to the stomach.
 Gastrocnemius, (yaarrjg, the belly, and xvrjfirj, the leg), the  muscle
       forming the thick of  the leg.
 Gastro-Epiploic, (yaaxyg, the stomach, and emnloov, the caul), be-
       longing to the stomach and omentum.
 Gelatine, (gelu), jelly.
 Genio, (yeveiov, the chin);  names  compounded with this word be-
       long to  muscles attached to the chin.
 Gestation, (gestatio uterina), the period of pregnancy.
 Gijsglywivs(yiyylvfj.og,a. hinge),articulation admitting flexion and ex-
       tension.
 Glandula, (dim. of glans), a nut or acorn.
 Glenoid, (y^rjvrj, a cavity),  a part having a shallow cavity.
 Gliadine, (yha, glue), one  of the constituents of gluten.
 Glomer, a convoluted bundle of glands.
 Glosso, (y/Uocnra, the tongue); names compounded  with  this  word
        are applied to muscles attached to the tongue. 
326
GLOSSARY.
Glottis, (yhaxxig, lingula), the superior opening of the larynx.
Gluteus, (ylovxog, the buttock), muscles forming part of tlie buttocks.
Gomphosis, (yoficpoco, to drive in a nail), an articulation of bones, like
      a nail in a piece of wood.

                              H.

Hemorrhoidal, (ai/ua, blood, and gew, to flow), a term applied to the
      vessels of the rectum, because they often bleed.
Harmonia, (dgftovia, a close joining), a species of immovable artic-
      ulation.
Helix, (edw, to turn about), the outer bar or margin of the external
      ear.
Hepatic, (rjTiag, the liver), applied to parts belonging to the liver.
Hyaloid, (valog, glass), the capsule of the  vitreous humour of the
      eye.
Hymen, (the god of marriage), the membrane situated at the entrance
      of the virgin vagina.
Hyo ; names compounded with this word belong to muscles  which
      are attached to the —
Hyoides, Os, (v, and eidog, shape), a bone of the tongue resembling
      the Greek upsilon, v.
Hypochondrium, (ino, under, and %ovdgog, a cartilage), the upper
      region of the abdomen, under the cartilages of the ribs.
Hypogastric, (ino, under, and yaaxrjg,ihe belly), the lower region of
      the fore part of the abdomen.
Hypoglossus, (ino, under, and ylcoaaa, the tongue), parts which lie
      under the tongue.
Hypothenar, (ino, under, and Oevag, the  palm of the  hand), one of
      the muscles contracting the thumb.


                              I.

Ileum,  (edeo, to turn), a  portion  of the small  intestine, so called
      from being found convoluted. 
GLOSSARY.
327
Incisores, (incidere, to cut), the fore-teeth.
Incus, (an anvil), a small  bone of the internal ear, with which  the
      malleus is articulated.
Index, (indico, to point out), the fore finger.
Infundibulum, (a funnel), a tube leading from the brain to the pitui-
      tary gland.
Innominatum, parts which have no proper name.
Interfemineum ; vide Perineum.
Interosseous, (inter and os), a term applied to parts situated between
      bones.
Iris, (the rainbow), the membrane round the pupil of the eye, deriv-
      ing its name from its various colors.
Ischium, (kt/co, to  support), that  part of the  os  innominatum upon
      which we sit.

                               J.

Jejunum, (empty), a portion of the small intestine, so called from
      being generally found empty.
Jugale, Os, the zygoma.

                               L.

Lacunae, (little cavities),  the excretory ducts of  the urethra, vagina,
       etc.
Lambdoidal, resembling the Greek lambda, A.
Lamella, dim. of—
Lamina, a scale or plate.  It is used for the foliated structure of bones
       or other organs.
Larynx,(lagvys), the superior part of the trachea.
Linea Alba, a white line formed by the meeting of the tendons of
       the abdominal muscles.
Lumbricales, (lumbricus, an earth-worm), four muscles of tlie hand
       and foot. 
328                     GLOSSARY.
                               M.

Masseter, (uaacraofiai, to chew), a muscle which assists in chewing.
Mastoid, (paoxog, a breast), shaped like a nipple or breast.
Maxilla, the jaw.
Meconium, (urjxav, a poppy), the excrements of the foetus are thus
       called, because  they have some resemblance  to  opium in
       color.
Mediana Vena, the middle vein of the arm, between the basilic and
       cephalic.
Mediastinum,  (medium, the  middle), a middle portion separating
       parts from each  other.
Medulla Spinalis, the spinal marrow or cord.
Membrana Nictitans, (nicto, to  wink), a membrane with which
       birds can occasionally cover the eye.
Meninges, (fivviy^, a membrane,) membranes which inclose the brain.
Mesentery, (fieaog, the middle, and evxegov, the intestine), the mem-
       brane in the middle of the intestines, by which  they  are at-
       tached to the spine.
Meseraic, (fxeaog, the  middle, and agaia, the small intestine,) the
       same as the last  article.
Mesocolon, ([xeaog, the middle,  xwlov, the colon), that part  of the
       mesentery in the middle of the colon.
Metacarpus, (fiexa, after, and xagnog, the wrist), that part  of the
       hand between the carpus and fingers.
Metatarsus, (fiexa, after,  and xagaog, the tarsus), that part of the
       foot between the tarsus and toes.
Mitralis Valvula, (mitra, a mitre), valves at the left ventricle of the
       heart, like a mitre.
Molar Teeth, the double, or grinding teeth.
Mucus, (fiv%a, the mucus of the nostrils), a transparent,  saline, gluti-
       nous fluid.
Mylo, ([ivlt], a grinder  tooth); names  compounded of this word be-
       long to muscles that are attached near the grinders. 
                         GLOSSARY.                     329

Myoides Platysma, a muscular expansion on the neck.  See Pla-
      TYSMA.
Myology, (uvg and loyog), the doctrine of the muscles.

                              N.

Naviculare, (navicula, a small boat), a bone of the carpus, and also
      of the tarsus.
Neurilemma, (vevgov, a nerve, and leftfia, a coat), the  sheath of a
      nerve.
Neurology, (vevgov, a nerve), the doctrine of the nerves.
Nymphe, two semicircular glandular membranes in the pudendum
      mulibre, so called because they direct the course of the urine.


                              O.

Odontoides, (odovg, a tooth, and eidog, shape), tooth-like.
CEsophagus, (oua, to carry, q>ayta, to eat), the canal leading from the
      pharynx to the stomach, carrying what is swallowed into the
      stomach.
Olecranon, (wlevrj, the cubit, xgavov, the head), the elbow, or head
      of the ulna.
Omentum, (omen, a guess), the  caul, so  called because the ancient
      priests prophesied from an inspection of this viscus.
Omo, (wuog, the shoulder);  names compounded of this word belong
      to muscles which are attached to the scapula.
Omo-Plata, (oifiog, the shoulder, and nlaxvg, broad),  the scapula or
      shoulder-blade.
Ophthalmic, (oydalfiog, an eye), relating to the eye.
Organ, (ogyavov), a part which has a determined office in the animal
      economy.
Osmazome, (oauv, flavor, and t,couog, broth), a peculiar principle ob-
      tained from muscular fibre, having the taste and smell of broth.
Osteology, (oaxeov, bone, and loyog, a discourse), the doctrine of the
      bones. 
330
GLOSSARY
                              P.

Palpi, (palpo, to grope or feel one's way), feelers.
Pampiniformis, (pampinus, a  vine-tendril, and forma, shape).  The
       spermatic vessels form a plexus, which, from  its similitude to
       the tendrils of a vine is called pampiniformis.
Pancreas, (itav, all, and xgeag, flesh), a gland of the abdomen.
Panniculus Carnosus, (pannus, a covering, and caro, flesh,) a fleshy
       covering.
Parenchyma, (nageyxeta,  to pour  through), a substance connecting
       the vessels, etc. of the lungs, liver, etc.
Parietalia, (paries, a wall), bones of the cranium, serving as a wall
       to the brain.
Parotid, (naga, near, and coxog, the gen. of ovg, the ear), a gland sit-
       uated near the ear.
Patella, (dim. of patina, a pan), the knee-pan.
Pathetics, (itadog, passion), the fourth  pair of nerves, because by
       means of these, the eyes express certain passions.
Pelvis, (rtelv^, a basin), the basin of the kidneys, or the lower part of
       the abdomen, in which the bladder and rectum (and in women
       also the uterus) are contained.
Pericardium, (negi, around, and  xagdia, the heart), the membrane
       surrounding the heart.
Perichondrium, (negi and xovdQ°s)> synovial  membrane covering
       cartilage.
Pericranium, (negi,  around,  and  xgaviov, the  cranium), the  mem-
       brane covering the bones of the cranium.
Perineum, (negivaiov, to flow round, because that part is  generally
       moist), the space between the external parts of generation and
       the anus.
Periosteum, (negi, around, and oaxeov, a bone), the  membrane sur-
       rounding the bones.
Peristaltic, (negiaxeXka, to contract), the motion of the intestines.
Peritoneum, (negixeva, to extend  round), the membrane  lining the
       abdomen, and covering  its organs. 
                          GLOSSARY.                     J31

 Perone, (negovij), the fibula or small bone of the leg.
 Petrosum, Os, (nexga, a rock), part of the temporal bone.
 Phalanx, (an army), the  bones of the fingers and toes are  called
       phalanges, from their regularity.
 Pharynx, (<pagvy%), a membranous bag at the back end of the mouth,
       leading to the stomach.
 Phrenic, (cpgeveg, the diaphragm, (pgtjv, the mind, because the  dia-
       phragm was supposed  to be the seat of the mind), the name of
       a nerve, etc.
 Physiology, (cpvoig, nature), that science which has for  its object a
       knowledge of the actions and functions of the living body.
 Pia Mater, the innermost membrane around the brain.
 Picromel, (mxgog, bitter, and fieXi, honey), the characteristic princi-
       ple of bile.
 Pisiform, (pea-like), a term applied  to  the  fourth  bone of the  first
       row of the carpus.
 Pituitary, (producing phlegm), a term applied to the membrane of
       the nose, etc.
 Placenta, (nXa%, a cake),  the after-birth.
 Plantaris, (planta, the sole), parts situated in the sole.
 Platysma-Myoides, (nXaxvg, broad, fivg, a muscle, and eidog, shape),
       a muscle of the neck.
 Pleura, (nXevga,  the side), a serous  membrane lining the cavity of
       the thorax.
 Plexus, (plecto, to weave together), a kind of net-work of blood ves-
       sels or nerves.
 Pneumonic, (nvevfuov, the  lung), appertaining to the lungs.
 Popliteus, (poples, the ham),  a muscle of the leg.
 Prepuce, the fore-skin of  the penis, which the eastern nations gen-
       erally cut off.
 Processus, (procedo, to start out), an eminence of bone.
 Prostate, (ngo, before, and iaxrj(M, to stand), a gland situated  before
       the vesiculce seminales.
Psoas, (ipoai, the loins), a muscle so named from its situation.
Pterygoid, (nxega, a wing), a process resembling  a wing. 
332                      GLOSSARY.
Pterygo-Staphylini, (nxegv%, .a wing, and arayvXy, a grape), mus-
      cles arising from the pterygoid process of the os sphenoides,
      and inserted into the uvula.
Pudenda, (pudor, shame), the parts of generation.
Pupilla, ( a little puppet), the round aperture in the iris of the eye.
Pylorus, (nvXagog, the keeper of a  gate), the lower  orifice of the
      stomach, guarding the entrance of the bowels.
Pyramidalis, a muscle having the form of a pyramid.
Pyriform, (pyrus), a muscle having the form of a pear.


                              R.

Rachidian, (gaxig, the spine), appertaining to the spine.
Radius, (the spoke of a wheel), the small bone of the fore-arm.
Ranular, like a frog or toad.
Raphe, (ganxco, to sew), a line having the appearance of a seam.
Rectum, the straight gut, the last of the intestines.
Region, a term applied to the respective divisions of the body.
Renal, appertaining to the kidney, from —
Renes, the kidneys, through which the urine flows.
Retina, (rete, a net), the net-like expansion of the optic nerve on the
      inner surface of  the eye.
Rhomboides, a muscle so called from resembling a geometrical figure
      [gofiftog), the sides of which are equal, but not right angled.
Rotula, (dim. of rota, a wheel), the knee-pan.


                              S.

Sacrum, (sacred), a bone so called because it was offered in sacrifice.
Sagittalis, (sagitla, an arrow), a suture in the cranium.
Saliva, the fluid secreted in the mouth.
Salvatella, (salvo, to  preserve), a vein of the foot, the opening of
      which was said to preserve health and cure melancholy.
Sanguis, the blood.
Saphena, (aaqpqg, manifest), the most obvious vein of the leg. 
                          GLOSSARY.                     333

Sartorius, (sartor, a tailor), the muscle by means of which  the tai-
      lor lays his legs across.
Scaleni, (axaXyvog, a geometrical figure with three unequal sides),
      muscles of the neck.
Scapha, (axaxp-q, a little boat), the depression of the outer ear before
      the anti-helix.
Scaphoides, (resembling a boat), a bone of the  carpus, and also  of
      the tarsus.
Scapula, the shoulder-blade.
Sclerotic, (axXygog, hard), the outermost or hardest membrane of
      the eye.
Scutiform, shaped like a shield.
Sebaceous, suety ; a term applied to glands which secrete an unctuous
      matter.
Sella Turcica, Sella  Equina, Sella Sphenoides,  are  various
      names for a part of the sphenoid bone resembling a Turkish
      saddle.
Septum Cordis, (sepes, a hedge), the fleshy substance which  sepa-
      rates the right from the left ventricle of the heart.
Sesamoid, (o-yaaf/Tj, an Indian bean), small  bones in the hands and
      feet resembling the semen sesami.
Sigmoid, resembling the Greek g, sigma.
Skeleton, (axeXXca, to dry), the articulated dry bones of  an animal.
Soleus, (solea, sole), a muscle of the leg having the form of that fish.
Spermatic, (anegfia, seed), parts belonging to the testis or ovarium.
Sphenoid, (aoprjv, a wedge), shaped like a wedge.
Sphincter, (aytyyco,  to constrict), the name of several muscles, the
      office of which is  to close the apertures around  which they
      are placed.
Splanchnology, (anXay/vov, the viscera), the description of the in-
      ternal  organs.
Splenius, (anXrjv, the spleen), a muscle so named from its resemblance
      to that organ.
Squamous, (squama, a scale), covering as the scales of fishes do each
      other. 
334
GLOSSARY.
 Stapes, (a stirrup), one of the small bones of the internal ear.
 Stearine, (aieag, fat), the more  solid part of one of the proximate
       principles of fat.
 Siomachus, (axoua, a mouth, and x£a>, to pour), the stomach.
 Styloid, (stylus, a pencil), a process like a pencil on the temporal and
       other bones.
 Succenturiatus, (succenturiare), to supply the place of another.
 Suture, (sutura, a seam), an appearance which is  most obvious  in
       in that union of the bones of the skull constituting the  dove
       tail  suture.
 Symphysis, (av/icpvoj, to  grow together), the  connection of  bones
       which have no manifest motion.
 Synarthrosis, (aw, with, and agOgov, a joint), articulation without
       manifest motion.
 Synchondrosis, (aw, with, and /ovdgog, a cartilage), articulation by
       means of intervening cartilage.
 Syndesmology, (avvdecruog, a ligament), the doctrine of ligaments.
 Syndesmosis, the connection of bones by ligaments.
 Syneurosis, (aw, with, and vevgov, a nerve), the connection of bones
       by tendon, formerly mistaken for nerve.
 Synthesis, (awnd^fii, to put together), the anatomical  connection,of
       the bones of the skeleton.
 Syssarcosis, (aw, with, and aag%, flesh), the connection of bones by
       muscle.
 Systole, (ovoteXXo), to contract); vide Diastole.

                               T.

 Talus, (a die), a bone of the tarsus.
Tarsus, the space between the bones of the leg and the metatarsus.
Temporal ; bones, etc. have been so named on  account of occupying
       the region of the head  on  which the hair generally first begins
       to turn gray, thus indicating the age.
Tendon, (xeivw, to extend), a fibrous cord at the extremity of a muscle.
Tentacula, (lento, to seize), organs by which certain animals attach
       themselves to surrounding objects. 
GLOSSARY
335
Teres, (round), the name of a muscle.
Testis, (a witness, quia est quasi testis virilitatis), the testicle.
Thalamus, (daXafiog, a bed), applied  to a  part of the brain from
      which the optic nerve takes its origin.
Theca, (a sheath); the spinal canal is often called theca vertebralis.
Thenar, (the palm of the hand), a muscle extending the thumb.
Thorax, (6oga%, the chest), or that part of the body which contains
      the heart and lungs.
Thymus, (dvfiog, a bulbous root), a temporary gland in the thorax.
Thyreo ; names compounded with this  word belong to muscles
       which are attached to the —
Thyroid, (dvgeog, a shield), a cartilage of the larynx compared to a
       shield.
Tibia, (a pipe  or flute), the great bone of the leg.
Tonsils, the round glands placed between the arches of the palate.
Trachea, (xgaxvg, rough), the windpipe.
Tragus, (a goat), a small eminence of the  external ear, upon which
       hair often grows like the beard of a goat.
Trapezoid, like a trapezium.
Trochanter, (xgoxaoj, to run or to roll), a process of the thigh bone,
       the muscles inserted  into which greatly contribute to the ac-
       tion of running.
Trochlea, (xgoxaXia, a pulley), a kind of cartilaginous pulley.
Trochlearis, an articulation where  one part moves round another
       like a pulley.
Tube Fallopiane, two canals at the fundus uteri of a trumpet form,
       described by Fallopius.
Tympanum, the drum of the ear.

                              U.

Ulna, (loXevrj,  the cubit), one of the bones of the fore-arm.
Umbilicus, (ofupaXog), the navel.
Urachus, (ovgov, urine, and ^ew, to pour), a ligament of the bladder,
       occupying the place of the urinary passage of the fcetal quad-
       ruped,  which goes into the allantois. 
336
GLOSSARY.
Ureter, (ovgov, urine), the canal that transmits the urine from the
       kidney into the bladder.
Urethra, (ovgrjdga), the canal through which urine passes from the
       bladder.
Uterus, (vgxega, matrix), the womb.
Uvea, (uva, a grape), the posterior lamina of the iris.
Uvula, the pendulous body which hangs down from  the  middle of
       the soft palate.

                              V.

Valves, (vcdva>, folding doors), little membranes  preventing  the re-
       turn of the fluids in the blood vessels and absorbents.
Ventricle, (venter,  the stomach), applied in anatomy to the  cavities
       of the brain and heart.
Vertebre, (verto, to turn), the bones of the spine.
Vesicle, (vesica, bladder), a small bladder-like cavity.
Vomer, (a ploughshare), a bone of the nose.

                              X.

Xiphoid, (Ziyog, a sword,) like a sword, a term applied to the carti-
       lage of the sternum.

                              Z.

Zygoma, (t,vyog, a yoke), the arch formed by the zygomatic  processes
       of the  temporal and cheek bones. 
 
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